IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network100.0.0.0/7

Usable hosts33,554,430

Subnet mask254.0.0.0

Addresses33,554,432

Network address: 100.0.0.0
Broadcast address: 101.255.255.255
First usable: 100.0.0.1
Last usable: 101.255.255.254
Usable hosts: 33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask: 254.0.0.0
Wildcard mask: 1.255.255.255 (Cisco ACLs, OSPF)
Prefix length: /7
Type: Public public
Old class: A (default /8)
As numbers: Hex 64000000 · Integer 1677721600 to 1711276031
Reverse DNS zones: 100.in-addr.arpa
101.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.

Binary

Binary view
	Binary (network bits bold, host bits grey)	Dotted
Address	`01100100.00000000.00000000.00000000`	`100.0.0.0`
Subnet mask	`11111110.00000000.00000000.00000000`	`254.0.0.0`
Network	`01100100.00000000.00000000.00000000`	`100.0.0.0`
Broadcast	`01100101.11111111.11111111.11111111`	`101.255.255.255`

Split into smaller subnets/15

/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

100.0.0.0/7 makes 256 subnets of /15.

Subnets
#	Subnet	Usable hosts range	Broadcast	Hosts
1	`100.0.0.0/15`	`100.0.0.1` to `100.1.255.254`	100.1.255.255	131,070
2	`100.2.0.0/15`	`100.2.0.1` to `100.3.255.254`	100.3.255.255	131,070
3	`100.4.0.0/15`	`100.4.0.1` to `100.5.255.254`	100.5.255.255	131,070
4	`100.6.0.0/15`	`100.6.0.1` to `100.7.255.254`	100.7.255.255	131,070
5	`100.8.0.0/15`	`100.8.0.1` to `100.9.255.254`	100.9.255.255	131,070
6	`100.10.0.0/15`	`100.10.0.1` to `100.11.255.254`	100.11.255.255	131,070
7	`100.12.0.0/15`	`100.12.0.1` to `100.13.255.254`	100.13.255.255	131,070
8	`100.14.0.0/15`	`100.14.0.1` to `100.15.255.254`	100.15.255.255	131,070
9	`100.16.0.0/15`	`100.16.0.1` to `100.17.255.254`	100.17.255.255	131,070
10	`100.18.0.0/15`	`100.18.0.1` to `100.19.255.254`	100.19.255.255	131,070
11	`100.20.0.0/15`	`100.20.0.1` to `100.21.255.254`	100.21.255.255	131,070
12	`100.22.0.0/15`	`100.22.0.1` to `100.23.255.254`	100.23.255.255	131,070
13	`100.24.0.0/15`	`100.24.0.1` to `100.25.255.254`	100.25.255.255	131,070
14	`100.26.0.0/15`	`100.26.0.1` to `100.27.255.254`	100.27.255.255	131,070
15	`100.28.0.0/15`	`100.28.0.1` to `100.29.255.254`	100.29.255.255	131,070
16	`100.30.0.0/15`	`100.30.0.1` to `100.31.255.254`	100.31.255.255	131,070
17	`100.32.0.0/15`	`100.32.0.1` to `100.33.255.254`	100.33.255.255	131,070
18	`100.34.0.0/15`	`100.34.0.1` to `100.35.255.254`	100.35.255.255	131,070
19	`100.36.0.0/15`	`100.36.0.1` to `100.37.255.254`	100.37.255.255	131,070
20	`100.38.0.0/15`	`100.38.0.1` to `100.39.255.254`	100.39.255.255	131,070
21	`100.40.0.0/15`	`100.40.0.1` to `100.41.255.254`	100.41.255.255	131,070
22	`100.42.0.0/15`	`100.42.0.1` to `100.43.255.254`	100.43.255.255	131,070
23	`100.44.0.0/15`	`100.44.0.1` to `100.45.255.254`	100.45.255.255	131,070
24	`100.46.0.0/15`	`100.46.0.1` to `100.47.255.254`	100.47.255.255	131,070
25	`100.48.0.0/15`	`100.48.0.1` to `100.49.255.254`	100.49.255.255	131,070
26	`100.50.0.0/15`	`100.50.0.1` to `100.51.255.254`	100.51.255.255	131,070
27	`100.52.0.0/15`	`100.52.0.1` to `100.53.255.254`	100.53.255.255	131,070
28	`100.54.0.0/15`	`100.54.0.1` to `100.55.255.254`	100.55.255.255	131,070
29	`100.56.0.0/15`	`100.56.0.1` to `100.57.255.254`	100.57.255.255	131,070
30	`100.58.0.0/15`	`100.58.0.1` to `100.59.255.254`	100.59.255.255	131,070
31	`100.60.0.0/15`	`100.60.0.1` to `100.61.255.254`	100.61.255.255	131,070
32	`100.62.0.0/15`	`100.62.0.1` to `100.63.255.254`	100.63.255.255	131,070
33	`100.64.0.0/15`	`100.64.0.1` to `100.65.255.254`	100.65.255.255	131,070
34	`100.66.0.0/15`	`100.66.0.1` to `100.67.255.254`	100.67.255.255	131,070
35	`100.68.0.0/15`	`100.68.0.1` to `100.69.255.254`	100.69.255.255	131,070
36	`100.70.0.0/15`	`100.70.0.1` to `100.71.255.254`	100.71.255.255	131,070
37	`100.72.0.0/15`	`100.72.0.1` to `100.73.255.254`	100.73.255.255	131,070
38	`100.74.0.0/15`	`100.74.0.1` to `100.75.255.254`	100.75.255.255	131,070
39	`100.76.0.0/15`	`100.76.0.1` to `100.77.255.254`	100.77.255.255	131,070
40	`100.78.0.0/15`	`100.78.0.1` to `100.79.255.254`	100.79.255.255	131,070
41	`100.80.0.0/15`	`100.80.0.1` to `100.81.255.254`	100.81.255.255	131,070
42	`100.82.0.0/15`	`100.82.0.1` to `100.83.255.254`	100.83.255.255	131,070
43	`100.84.0.0/15`	`100.84.0.1` to `100.85.255.254`	100.85.255.255	131,070
44	`100.86.0.0/15`	`100.86.0.1` to `100.87.255.254`	100.87.255.255	131,070
45	`100.88.0.0/15`	`100.88.0.1` to `100.89.255.254`	100.89.255.255	131,070
46	`100.90.0.0/15`	`100.90.0.1` to `100.91.255.254`	100.91.255.255	131,070
47	`100.92.0.0/15`	`100.92.0.1` to `100.93.255.254`	100.93.255.255	131,070
48	`100.94.0.0/15`	`100.94.0.1` to `100.95.255.254`	100.95.255.255	131,070
49	`100.96.0.0/15`	`100.96.0.1` to `100.97.255.254`	100.97.255.255	131,070
50	`100.98.0.0/15`	`100.98.0.1` to `100.99.255.254`	100.99.255.255	131,070
51	`100.100.0.0/15`	`100.100.0.1` to `100.101.255.254`	100.101.255.255	131,070
52	`100.102.0.0/15`	`100.102.0.1` to `100.103.255.254`	100.103.255.255	131,070
53	`100.104.0.0/15`	`100.104.0.1` to `100.105.255.254`	100.105.255.255	131,070
54	`100.106.0.0/15`	`100.106.0.1` to `100.107.255.254`	100.107.255.255	131,070
55	`100.108.0.0/15`	`100.108.0.1` to `100.109.255.254`	100.109.255.255	131,070
56	`100.110.0.0/15`	`100.110.0.1` to `100.111.255.254`	100.111.255.255	131,070
57	`100.112.0.0/15`	`100.112.0.1` to `100.113.255.254`	100.113.255.255	131,070
58	`100.114.0.0/15`	`100.114.0.1` to `100.115.255.254`	100.115.255.255	131,070
59	`100.116.0.0/15`	`100.116.0.1` to `100.117.255.254`	100.117.255.255	131,070
60	`100.118.0.0/15`	`100.118.0.1` to `100.119.255.254`	100.119.255.255	131,070
61	`100.120.0.0/15`	`100.120.0.1` to `100.121.255.254`	100.121.255.255	131,070
62	`100.122.0.0/15`	`100.122.0.1` to `100.123.255.254`	100.123.255.255	131,070
63	`100.124.0.0/15`	`100.124.0.1` to `100.125.255.254`	100.125.255.255	131,070
64	`100.126.0.0/15`	`100.126.0.1` to `100.127.255.254`	100.127.255.255	131,070
65	`100.128.0.0/15`	`100.128.0.1` to `100.129.255.254`	100.129.255.255	131,070
66	`100.130.0.0/15`	`100.130.0.1` to `100.131.255.254`	100.131.255.255	131,070
67	`100.132.0.0/15`	`100.132.0.1` to `100.133.255.254`	100.133.255.255	131,070
68	`100.134.0.0/15`	`100.134.0.1` to `100.135.255.254`	100.135.255.255	131,070
69	`100.136.0.0/15`	`100.136.0.1` to `100.137.255.254`	100.137.255.255	131,070
70	`100.138.0.0/15`	`100.138.0.1` to `100.139.255.254`	100.139.255.255	131,070
71	`100.140.0.0/15`	`100.140.0.1` to `100.141.255.254`	100.141.255.255	131,070
72	`100.142.0.0/15`	`100.142.0.1` to `100.143.255.254`	100.143.255.255	131,070
73	`100.144.0.0/15`	`100.144.0.1` to `100.145.255.254`	100.145.255.255	131,070
74	`100.146.0.0/15`	`100.146.0.1` to `100.147.255.254`	100.147.255.255	131,070
75	`100.148.0.0/15`	`100.148.0.1` to `100.149.255.254`	100.149.255.255	131,070
76	`100.150.0.0/15`	`100.150.0.1` to `100.151.255.254`	100.151.255.255	131,070
77	`100.152.0.0/15`	`100.152.0.1` to `100.153.255.254`	100.153.255.255	131,070
78	`100.154.0.0/15`	`100.154.0.1` to `100.155.255.254`	100.155.255.255	131,070
79	`100.156.0.0/15`	`100.156.0.1` to `100.157.255.254`	100.157.255.255	131,070
80	`100.158.0.0/15`	`100.158.0.1` to `100.159.255.254`	100.159.255.255	131,070
81	`100.160.0.0/15`	`100.160.0.1` to `100.161.255.254`	100.161.255.255	131,070
82	`100.162.0.0/15`	`100.162.0.1` to `100.163.255.254`	100.163.255.255	131,070
83	`100.164.0.0/15`	`100.164.0.1` to `100.165.255.254`	100.165.255.255	131,070
84	`100.166.0.0/15`	`100.166.0.1` to `100.167.255.254`	100.167.255.255	131,070
85	`100.168.0.0/15`	`100.168.0.1` to `100.169.255.254`	100.169.255.255	131,070
86	`100.170.0.0/15`	`100.170.0.1` to `100.171.255.254`	100.171.255.255	131,070
87	`100.172.0.0/15`	`100.172.0.1` to `100.173.255.254`	100.173.255.255	131,070
88	`100.174.0.0/15`	`100.174.0.1` to `100.175.255.254`	100.175.255.255	131,070
89	`100.176.0.0/15`	`100.176.0.1` to `100.177.255.254`	100.177.255.255	131,070
90	`100.178.0.0/15`	`100.178.0.1` to `100.179.255.254`	100.179.255.255	131,070
91	`100.180.0.0/15`	`100.180.0.1` to `100.181.255.254`	100.181.255.255	131,070
92	`100.182.0.0/15`	`100.182.0.1` to `100.183.255.254`	100.183.255.255	131,070
93	`100.184.0.0/15`	`100.184.0.1` to `100.185.255.254`	100.185.255.255	131,070
94	`100.186.0.0/15`	`100.186.0.1` to `100.187.255.254`	100.187.255.255	131,070
95	`100.188.0.0/15`	`100.188.0.1` to `100.189.255.254`	100.189.255.255	131,070
96	`100.190.0.0/15`	`100.190.0.1` to `100.191.255.254`	100.191.255.255	131,070
97	`100.192.0.0/15`	`100.192.0.1` to `100.193.255.254`	100.193.255.255	131,070
98	`100.194.0.0/15`	`100.194.0.1` to `100.195.255.254`	100.195.255.255	131,070
99	`100.196.0.0/15`	`100.196.0.1` to `100.197.255.254`	100.197.255.255	131,070
100	`100.198.0.0/15`	`100.198.0.1` to `100.199.255.254`	100.199.255.255	131,070
101	`100.200.0.0/15`	`100.200.0.1` to `100.201.255.254`	100.201.255.255	131,070
102	`100.202.0.0/15`	`100.202.0.1` to `100.203.255.254`	100.203.255.255	131,070
103	`100.204.0.0/15`	`100.204.0.1` to `100.205.255.254`	100.205.255.255	131,070
104	`100.206.0.0/15`	`100.206.0.1` to `100.207.255.254`	100.207.255.255	131,070
105	`100.208.0.0/15`	`100.208.0.1` to `100.209.255.254`	100.209.255.255	131,070
106	`100.210.0.0/15`	`100.210.0.1` to `100.211.255.254`	100.211.255.255	131,070
107	`100.212.0.0/15`	`100.212.0.1` to `100.213.255.254`	100.213.255.255	131,070
108	`100.214.0.0/15`	`100.214.0.1` to `100.215.255.254`	100.215.255.255	131,070
109	`100.216.0.0/15`	`100.216.0.1` to `100.217.255.254`	100.217.255.255	131,070
110	`100.218.0.0/15`	`100.218.0.1` to `100.219.255.254`	100.219.255.255	131,070
111	`100.220.0.0/15`	`100.220.0.1` to `100.221.255.254`	100.221.255.255	131,070
112	`100.222.0.0/15`	`100.222.0.1` to `100.223.255.254`	100.223.255.255	131,070
113	`100.224.0.0/15`	`100.224.0.1` to `100.225.255.254`	100.225.255.255	131,070
114	`100.226.0.0/15`	`100.226.0.1` to `100.227.255.254`	100.227.255.255	131,070
115	`100.228.0.0/15`	`100.228.0.1` to `100.229.255.254`	100.229.255.255	131,070
116	`100.230.0.0/15`	`100.230.0.1` to `100.231.255.254`	100.231.255.255	131,070
117	`100.232.0.0/15`	`100.232.0.1` to `100.233.255.254`	100.233.255.255	131,070
118	`100.234.0.0/15`	`100.234.0.1` to `100.235.255.254`	100.235.255.255	131,070
119	`100.236.0.0/15`	`100.236.0.1` to `100.237.255.254`	100.237.255.255	131,070
120	`100.238.0.0/15`	`100.238.0.1` to `100.239.255.254`	100.239.255.255	131,070
121	`100.240.0.0/15`	`100.240.0.1` to `100.241.255.254`	100.241.255.255	131,070
122	`100.242.0.0/15`	`100.242.0.1` to `100.243.255.254`	100.243.255.255	131,070
123	`100.244.0.0/15`	`100.244.0.1` to `100.245.255.254`	100.245.255.255	131,070
124	`100.246.0.0/15`	`100.246.0.1` to `100.247.255.254`	100.247.255.255	131,070
125	`100.248.0.0/15`	`100.248.0.1` to `100.249.255.254`	100.249.255.255	131,070
126	`100.250.0.0/15`	`100.250.0.1` to `100.251.255.254`	100.251.255.255	131,070
127	`100.252.0.0/15`	`100.252.0.1` to `100.253.255.254`	100.253.255.255	131,070
128	`100.254.0.0/15`	`100.254.0.1` to `100.255.255.254`	100.255.255.255	131,070
129	`101.0.0.0/15`	`101.0.0.1` to `101.1.255.254`	101.1.255.255	131,070
130	`101.2.0.0/15`	`101.2.0.1` to `101.3.255.254`	101.3.255.255	131,070
131	`101.4.0.0/15`	`101.4.0.1` to `101.5.255.254`	101.5.255.255	131,070
132	`101.6.0.0/15`	`101.6.0.1` to `101.7.255.254`	101.7.255.255	131,070
133	`101.8.0.0/15`	`101.8.0.1` to `101.9.255.254`	101.9.255.255	131,070
134	`101.10.0.0/15`	`101.10.0.1` to `101.11.255.254`	101.11.255.255	131,070
135	`101.12.0.0/15`	`101.12.0.1` to `101.13.255.254`	101.13.255.255	131,070
136	`101.14.0.0/15`	`101.14.0.1` to `101.15.255.254`	101.15.255.255	131,070
137	`101.16.0.0/15`	`101.16.0.1` to `101.17.255.254`	101.17.255.255	131,070
138	`101.18.0.0/15`	`101.18.0.1` to `101.19.255.254`	101.19.255.255	131,070
139	`101.20.0.0/15`	`101.20.0.1` to `101.21.255.254`	101.21.255.255	131,070
140	`101.22.0.0/15`	`101.22.0.1` to `101.23.255.254`	101.23.255.255	131,070
141	`101.24.0.0/15`	`101.24.0.1` to `101.25.255.254`	101.25.255.255	131,070
142	`101.26.0.0/15`	`101.26.0.1` to `101.27.255.254`	101.27.255.255	131,070
143	`101.28.0.0/15`	`101.28.0.1` to `101.29.255.254`	101.29.255.255	131,070
144	`101.30.0.0/15`	`101.30.0.1` to `101.31.255.254`	101.31.255.255	131,070
145	`101.32.0.0/15`	`101.32.0.1` to `101.33.255.254`	101.33.255.255	131,070
146	`101.34.0.0/15`	`101.34.0.1` to `101.35.255.254`	101.35.255.255	131,070
147	`101.36.0.0/15`	`101.36.0.1` to `101.37.255.254`	101.37.255.255	131,070
148	`101.38.0.0/15`	`101.38.0.1` to `101.39.255.254`	101.39.255.255	131,070
149	`101.40.0.0/15`	`101.40.0.1` to `101.41.255.254`	101.41.255.255	131,070
150	`101.42.0.0/15`	`101.42.0.1` to `101.43.255.254`	101.43.255.255	131,070
151	`101.44.0.0/15`	`101.44.0.1` to `101.45.255.254`	101.45.255.255	131,070
152	`101.46.0.0/15`	`101.46.0.1` to `101.47.255.254`	101.47.255.255	131,070
153	`101.48.0.0/15`	`101.48.0.1` to `101.49.255.254`	101.49.255.255	131,070
154	`101.50.0.0/15`	`101.50.0.1` to `101.51.255.254`	101.51.255.255	131,070
155	`101.52.0.0/15`	`101.52.0.1` to `101.53.255.254`	101.53.255.255	131,070
156	`101.54.0.0/15`	`101.54.0.1` to `101.55.255.254`	101.55.255.255	131,070
157	`101.56.0.0/15`	`101.56.0.1` to `101.57.255.254`	101.57.255.255	131,070
158	`101.58.0.0/15`	`101.58.0.1` to `101.59.255.254`	101.59.255.255	131,070
159	`101.60.0.0/15`	`101.60.0.1` to `101.61.255.254`	101.61.255.255	131,070
160	`101.62.0.0/15`	`101.62.0.1` to `101.63.255.254`	101.63.255.255	131,070
161	`101.64.0.0/15`	`101.64.0.1` to `101.65.255.254`	101.65.255.255	131,070
162	`101.66.0.0/15`	`101.66.0.1` to `101.67.255.254`	101.67.255.255	131,070
163	`101.68.0.0/15`	`101.68.0.1` to `101.69.255.254`	101.69.255.255	131,070
164	`101.70.0.0/15`	`101.70.0.1` to `101.71.255.254`	101.71.255.255	131,070
165	`101.72.0.0/15`	`101.72.0.1` to `101.73.255.254`	101.73.255.255	131,070
166	`101.74.0.0/15`	`101.74.0.1` to `101.75.255.254`	101.75.255.255	131,070
167	`101.76.0.0/15`	`101.76.0.1` to `101.77.255.254`	101.77.255.255	131,070
168	`101.78.0.0/15`	`101.78.0.1` to `101.79.255.254`	101.79.255.255	131,070
169	`101.80.0.0/15`	`101.80.0.1` to `101.81.255.254`	101.81.255.255	131,070
170	`101.82.0.0/15`	`101.82.0.1` to `101.83.255.254`	101.83.255.255	131,070
171	`101.84.0.0/15`	`101.84.0.1` to `101.85.255.254`	101.85.255.255	131,070
172	`101.86.0.0/15`	`101.86.0.1` to `101.87.255.254`	101.87.255.255	131,070
173	`101.88.0.0/15`	`101.88.0.1` to `101.89.255.254`	101.89.255.255	131,070
174	`101.90.0.0/15`	`101.90.0.1` to `101.91.255.254`	101.91.255.255	131,070
175	`101.92.0.0/15`	`101.92.0.1` to `101.93.255.254`	101.93.255.255	131,070
176	`101.94.0.0/15`	`101.94.0.1` to `101.95.255.254`	101.95.255.255	131,070
177	`101.96.0.0/15`	`101.96.0.1` to `101.97.255.254`	101.97.255.255	131,070
178	`101.98.0.0/15`	`101.98.0.1` to `101.99.255.254`	101.99.255.255	131,070
179	`101.100.0.0/15`	`101.100.0.1` to `101.101.255.254`	101.101.255.255	131,070
180	`101.102.0.0/15`	`101.102.0.1` to `101.103.255.254`	101.103.255.255	131,070
181	`101.104.0.0/15`	`101.104.0.1` to `101.105.255.254`	101.105.255.255	131,070
182	`101.106.0.0/15`	`101.106.0.1` to `101.107.255.254`	101.107.255.255	131,070
183	`101.108.0.0/15`	`101.108.0.1` to `101.109.255.254`	101.109.255.255	131,070
184	`101.110.0.0/15`	`101.110.0.1` to `101.111.255.254`	101.111.255.255	131,070
185	`101.112.0.0/15`	`101.112.0.1` to `101.113.255.254`	101.113.255.255	131,070
186	`101.114.0.0/15`	`101.114.0.1` to `101.115.255.254`	101.115.255.255	131,070
187	`101.116.0.0/15`	`101.116.0.1` to `101.117.255.254`	101.117.255.255	131,070
188	`101.118.0.0/15`	`101.118.0.1` to `101.119.255.254`	101.119.255.255	131,070
189	`101.120.0.0/15`	`101.120.0.1` to `101.121.255.254`	101.121.255.255	131,070
190	`101.122.0.0/15`	`101.122.0.1` to `101.123.255.254`	101.123.255.255	131,070
191	`101.124.0.0/15`	`101.124.0.1` to `101.125.255.254`	101.125.255.255	131,070
192	`101.126.0.0/15`	`101.126.0.1` to `101.127.255.254`	101.127.255.255	131,070
193	`101.128.0.0/15`	`101.128.0.1` to `101.129.255.254`	101.129.255.255	131,070
194	`101.130.0.0/15`	`101.130.0.1` to `101.131.255.254`	101.131.255.255	131,070
195	`101.132.0.0/15`	`101.132.0.1` to `101.133.255.254`	101.133.255.255	131,070
196	`101.134.0.0/15`	`101.134.0.1` to `101.135.255.254`	101.135.255.255	131,070
197	`101.136.0.0/15`	`101.136.0.1` to `101.137.255.254`	101.137.255.255	131,070
198	`101.138.0.0/15`	`101.138.0.1` to `101.139.255.254`	101.139.255.255	131,070
199	`101.140.0.0/15`	`101.140.0.1` to `101.141.255.254`	101.141.255.255	131,070
200	`101.142.0.0/15`	`101.142.0.1` to `101.143.255.254`	101.143.255.255	131,070
201	`101.144.0.0/15`	`101.144.0.1` to `101.145.255.254`	101.145.255.255	131,070
202	`101.146.0.0/15`	`101.146.0.1` to `101.147.255.254`	101.147.255.255	131,070
203	`101.148.0.0/15`	`101.148.0.1` to `101.149.255.254`	101.149.255.255	131,070
204	`101.150.0.0/15`	`101.150.0.1` to `101.151.255.254`	101.151.255.255	131,070
205	`101.152.0.0/15`	`101.152.0.1` to `101.153.255.254`	101.153.255.255	131,070
206	`101.154.0.0/15`	`101.154.0.1` to `101.155.255.254`	101.155.255.255	131,070
207	`101.156.0.0/15`	`101.156.0.1` to `101.157.255.254`	101.157.255.255	131,070
208	`101.158.0.0/15`	`101.158.0.1` to `101.159.255.254`	101.159.255.255	131,070
209	`101.160.0.0/15`	`101.160.0.1` to `101.161.255.254`	101.161.255.255	131,070
210	`101.162.0.0/15`	`101.162.0.1` to `101.163.255.254`	101.163.255.255	131,070
211	`101.164.0.0/15`	`101.164.0.1` to `101.165.255.254`	101.165.255.255	131,070
212	`101.166.0.0/15`	`101.166.0.1` to `101.167.255.254`	101.167.255.255	131,070
213	`101.168.0.0/15`	`101.168.0.1` to `101.169.255.254`	101.169.255.255	131,070
214	`101.170.0.0/15`	`101.170.0.1` to `101.171.255.254`	101.171.255.255	131,070
215	`101.172.0.0/15`	`101.172.0.1` to `101.173.255.254`	101.173.255.255	131,070
216	`101.174.0.0/15`	`101.174.0.1` to `101.175.255.254`	101.175.255.255	131,070
217	`101.176.0.0/15`	`101.176.0.1` to `101.177.255.254`	101.177.255.255	131,070
218	`101.178.0.0/15`	`101.178.0.1` to `101.179.255.254`	101.179.255.255	131,070
219	`101.180.0.0/15`	`101.180.0.1` to `101.181.255.254`	101.181.255.255	131,070
220	`101.182.0.0/15`	`101.182.0.1` to `101.183.255.254`	101.183.255.255	131,070
221	`101.184.0.0/15`	`101.184.0.1` to `101.185.255.254`	101.185.255.255	131,070
222	`101.186.0.0/15`	`101.186.0.1` to `101.187.255.254`	101.187.255.255	131,070
223	`101.188.0.0/15`	`101.188.0.1` to `101.189.255.254`	101.189.255.255	131,070
224	`101.190.0.0/15`	`101.190.0.1` to `101.191.255.254`	101.191.255.255	131,070
225	`101.192.0.0/15`	`101.192.0.1` to `101.193.255.254`	101.193.255.255	131,070
226	`101.194.0.0/15`	`101.194.0.1` to `101.195.255.254`	101.195.255.255	131,070
227	`101.196.0.0/15`	`101.196.0.1` to `101.197.255.254`	101.197.255.255	131,070
228	`101.198.0.0/15`	`101.198.0.1` to `101.199.255.254`	101.199.255.255	131,070
229	`101.200.0.0/15`	`101.200.0.1` to `101.201.255.254`	101.201.255.255	131,070
230	`101.202.0.0/15`	`101.202.0.1` to `101.203.255.254`	101.203.255.255	131,070
231	`101.204.0.0/15`	`101.204.0.1` to `101.205.255.254`	101.205.255.255	131,070
232	`101.206.0.0/15`	`101.206.0.1` to `101.207.255.254`	101.207.255.255	131,070
233	`101.208.0.0/15`	`101.208.0.1` to `101.209.255.254`	101.209.255.255	131,070
234	`101.210.0.0/15`	`101.210.0.1` to `101.211.255.254`	101.211.255.255	131,070
235	`101.212.0.0/15`	`101.212.0.1` to `101.213.255.254`	101.213.255.255	131,070
236	`101.214.0.0/15`	`101.214.0.1` to `101.215.255.254`	101.215.255.255	131,070
237	`101.216.0.0/15`	`101.216.0.1` to `101.217.255.254`	101.217.255.255	131,070
238	`101.218.0.0/15`	`101.218.0.1` to `101.219.255.254`	101.219.255.255	131,070
239	`101.220.0.0/15`	`101.220.0.1` to `101.221.255.254`	101.221.255.255	131,070
240	`101.222.0.0/15`	`101.222.0.1` to `101.223.255.254`	101.223.255.255	131,070
241	`101.224.0.0/15`	`101.224.0.1` to `101.225.255.254`	101.225.255.255	131,070
242	`101.226.0.0/15`	`101.226.0.1` to `101.227.255.254`	101.227.255.255	131,070
243	`101.228.0.0/15`	`101.228.0.1` to `101.229.255.254`	101.229.255.255	131,070
244	`101.230.0.0/15`	`101.230.0.1` to `101.231.255.254`	101.231.255.255	131,070
245	`101.232.0.0/15`	`101.232.0.1` to `101.233.255.254`	101.233.255.255	131,070
246	`101.234.0.0/15`	`101.234.0.1` to `101.235.255.254`	101.235.255.255	131,070
247	`101.236.0.0/15`	`101.236.0.1` to `101.237.255.254`	101.237.255.255	131,070
248	`101.238.0.0/15`	`101.238.0.1` to `101.239.255.254`	101.239.255.255	131,070
249	`101.240.0.0/15`	`101.240.0.1` to `101.241.255.254`	101.241.255.255	131,070
250	`101.242.0.0/15`	`101.242.0.1` to `101.243.255.254`	101.243.255.255	131,070
251	`101.244.0.0/15`	`101.244.0.1` to `101.245.255.254`	101.245.255.255	131,070
252	`101.246.0.0/15`	`101.246.0.1` to `101.247.255.254`	101.247.255.255	131,070
253	`101.248.0.0/15`	`101.248.0.1` to `101.249.255.254`	101.249.255.255	131,070
254	`101.250.0.0/15`	`101.250.0.1` to `101.251.255.254`	101.251.255.255	131,070
255	`101.252.0.0/15`	`101.252.0.1` to `101.253.255.254`	101.253.255.255	131,070
256	`101.254.0.0/15`	`101.254.0.1` to `101.255.255.254`	101.255.255.255	131,070

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
Prefix	Subnet mask	Wildcard	Addresses	Usable hosts	Size	Typical use
/0	0.0.0.0	255.255.255.255	4,294,967,296	4,294,967,294	16,777,216 × /24
/1	128.0.0.0	127.255.255.255	2,147,483,648	2,147,483,646	8,388,608 × /24
/2	192.0.0.0	63.255.255.255	1,073,741,824	1,073,741,822	4,194,304 × /24
/3	224.0.0.0	31.255.255.255	536,870,912	536,870,910	2,097,152 × /24
/4	240.0.0.0	15.255.255.255	268,435,456	268,435,454	1,048,576 × /24
/5	248.0.0.0	7.255.255.255	134,217,728	134,217,726	524,288 × /24
/6	252.0.0.0	3.255.255.255	67,108,864	67,108,862	262,144 × /24
/7	254.0.0.0	1.255.255.255	33,554,432	33,554,430	131,072 × /24
/8	255.0.0.0	0.255.255.255	16,777,216	16,777,214	65,536 × /24	Old class A; 10.0.0.0/8
/9	255.128.0.0	0.127.255.255	8,388,608	8,388,606	32,768 × /24
/10	255.192.0.0	0.63.255.255	4,194,304	4,194,302	16,384 × /24
/11	255.224.0.0	0.31.255.255	2,097,152	2,097,150	8,192 × /24
/12	255.240.0.0	0.15.255.255	1,048,576	1,048,574	4,096 × /24	172.16.0.0/12
/13	255.248.0.0	0.7.255.255	524,288	524,286	2,048 × /24
/14	255.252.0.0	0.3.255.255	262,144	262,142	1,024 × /24
/15	255.254.0.0	0.1.255.255	131,072	131,070	512 × /24
/16	255.255.0.0	0.0.255.255	65,536	65,534	256 × /24	Old class B; 192.168.0.0/16
/17	255.255.128.0	0.0.127.255	32,768	32,766	128 × /24
/18	255.255.192.0	0.0.63.255	16,384	16,382	64 × /24
/19	255.255.224.0	0.0.31.255	8,192	8,190	32 × /24
/20	255.255.240.0	0.0.15.255	4,096	4,094	16 × /24
/21	255.255.248.0	0.0.7.255	2,048	2,046	8 × /24
/22	255.255.252.0	0.0.3.255	1,024	1,022	4 × /24	Large office or guest Wi-Fi (1,022 hosts)
/23	255.255.254.0	0.0.1.255	512	510	2 × /24	Larger office LAN (510 hosts)
/24	255.255.255.0	0.0.0.255	256	254	1 × /24	Typical office LAN (old class C)
/25	255.255.255.128	0.0.0.127	128	126	1/2 of a /24	Smaller LAN or VLAN
/26	255.255.255.192	0.0.0.63	64	62	1/4 of a /24	Smaller LAN or VLAN
/27	255.255.255.224	0.0.0.31	32	30	1/8 of a /24	Small VLAN, phones, cameras
/28	255.255.255.240	0.0.0.15	16	14	1/16 of a /24	Small VLAN, phones, cameras
/29	255.255.255.248	0.0.0.7	8	6	1/32 of a /24	Small fixed public block (5 usable)
/30	255.255.255.252	0.0.0.3	4	2	1/64 of a /24	Point-to-point (old style)
/31	255.255.255.254	0.0.0.1	2	2	1/128 of a /24	Point-to-point link (RFC 3021)
/32	255.255.255.255	0.0.0.0	1	1	1/256 of a /24	One host

IPv6 prefix reference

IPv6 prefix lengths
Prefix	Addresses	/64 LANs	/48 sites	Nibble	Typical use
/3	42,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)	2,305,843,009,213,693,952	35,184,372,088,832	No	All global unicast (2000::/3)
/16	5,192,296,858,534,827,628,530,496,329,220,096 (2^112)	281,474,976,710,656	4,294,967,296	Yes
/20	324,518,553,658,426,726,783,156,020,576,256 (2^108)	17,592,186,044,416	268,435,456	Yes	Large provider allocation (RIPE minimum for some)
/29	633,825,300,114,114,700,748,351,602,688 (2^99)	34,359,738,368	524,288	No	RIPE allocation to a provider (often)
/32	79,228,162,514,264,337,593,543,950,336 (2^96)	4,294,967,296	65,536	Yes	Provider allocation (RIPE default)
/36	4,951,760,157,141,521,099,596,496,896 (2^92)	268,435,456	4,096	Yes
/40	309,485,009,821,345,068,724,781,056 (2^88)	16,777,216	256	Yes
/44	19,342,813,113,834,066,795,298,816 (2^84)	1,048,576	16	Yes
/48	1,208,925,819,614,629,174,706,176 (2^80)	65,536	1	Yes	One site or organisation (RIPE PI / assignment)
/52	75,557,863,725,914,323,419,136 (2^76)	4,096		Yes
/56	4,722,366,482,869,645,213,696 (2^72)	256		Yes	Small site or home (common provider assignment)
/60	295,147,905,179,352,825,856 (2^68)	16		Yes	Some home broadband (16 LANs)
/64	18,446,744,073,709,551,616 (2^64)	1		Yes	One LAN or VLAN (needed for SLAAC)
/72	72,057,594,037,927,936 (2^56)	1/256 of a /64		Yes
/80	281,474,976,710,656 (2^48)	1/65,536 of a /64		Yes
/96	4,294,967,296	1/4,294,967,296 of a /64		Yes	Embeds an IPv4 address (NAT64)
/112	65,536	1/281,474,976,710,656 of a /64		Yes
/120	256	1/72,057,594,037,927,936 of a /64		Yes
/124	16	1/1,152,921,504,606,846,976 of a /64		Yes
/126	4	1/4,611,686,018,427,387,904 of a /64		No
/127	2	1/9,223,372,036,854,775,808 of a /64		No	Point-to-point link (RFC 6164)
/128	1	1/18,446,744,073,709,551,616 of a /64		Yes	One host or loopback

Private and special ranges

IPv4

Special-purpose ranges
Range	Name	What it is
`255.255.255.255/32`	Limited broadcast	Every host on the local network
`0.0.0.0/8`	This network	Not routed; 0.0.0.0 means "any address" in settings
`10.0.0.0/8`	Private (RFC 1918)	Office and home networks; not routed on the internet
`100.64.0.0/10`	Shared address space (CGNAT)	Used by providers behind carrier-grade NAT (RFC 6598)
`127.0.0.0/8`	Loopback	This computer
`169.254.0.0/16`	Link-local (APIPA)	Self-assigned when no DHCP server answers
`172.16.0.0/12`	Private (RFC 1918)	Office and home networks; not routed on the internet
`192.0.0.0/24`	IETF protocol assignments	Special uses such as DS-Lite
`192.0.2.0/24`	Documentation (TEST-NET-1)	For examples; never used on a network
`192.88.99.0/24`	6to4 relay (deprecated)	Formerly anycast for 6to4
`192.168.0.0/16`	Private (RFC 1918)	Office and home networks; not routed on the internet
`198.18.0.0/15`	Benchmarking	Network equipment testing (RFC 2544)
`198.51.100.0/24`	Documentation (TEST-NET-2)	For examples; never used on a network
`203.0.113.0/24`	Documentation (TEST-NET-3)	For examples; never used on a network
`224.0.0.0/4`	Multicast	One-to-many traffic, such as IPTV and routing protocols
`240.0.0.0/4`	Reserved	Future use; not usable on most systems

IPv6

Special-purpose ranges
Range	Name	What it is
`::/128`	Unspecified	No address; :: means "any address" in settings
`::1/128`	Loopback	This computer
`::ffff:0:0/96`	IPv4-mapped	An IPv4 address written as IPv6
`64:ff9b::/96`	NAT64	IPv4 addresses reached through a NAT64 gateway
`100::/64`	Discard only	Traffic sent here is dropped (RFC 6666)
`2001:db8::/32`	Documentation	For examples; never used on a network
`2001::/32`	Teredo	IPv6 tunnelled over IPv4 UDP
`2002::/16`	6to4	IPv6 tunnelled over IPv4 (largely retired)
`3fff::/20`	Documentation	For examples (RFC 9637)
`fc00::/7`	Unique local (ULA)	Private IPv6, like RFC 1918; usually fd00::/8
`fe80::/10`	Link-local	Every IPv6 interface has one; not routed
`ff00::/8`	Multicast	One-to-many traffic; replaces broadcast
`2000::/3`	Global unicast	Public internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.

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IP subnet calculator

IPv4 CIDR reference (/0 to /32)

IPv6 prefix reference

Private and special ranges

IPv4

IPv6

About this tool

Common questions

IPv4 CIDR reference (/0 to /32)

IPv6 prefix reference

Private and special ranges

IPv4

IPv6

Common questions

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