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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.

Network102.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
102.0.0.0
Broadcast address
103.255.255.255
First usable
102.0.0.1
Last usable
103.255.255.254
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 66000000 · Integer 1711276032 to 1744830463
Reverse DNS zones
102.in-addr.arpa
103.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
Address01100110.00000000.00000000.00000000102.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network01100110.00000000.00000000.00000000102.0.0.0
Broadcast01100111.11111111.11111111.11111111103.255.255.255
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)

102.0.0.0/7 makes 256 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1102.0.0.0/15102.0.0.1 to 102.1.255.254102.1.255.255131,070
2102.2.0.0/15102.2.0.1 to 102.3.255.254102.3.255.255131,070
3102.4.0.0/15102.4.0.1 to 102.5.255.254102.5.255.255131,070
4102.6.0.0/15102.6.0.1 to 102.7.255.254102.7.255.255131,070
5102.8.0.0/15102.8.0.1 to 102.9.255.254102.9.255.255131,070
6102.10.0.0/15102.10.0.1 to 102.11.255.254102.11.255.255131,070
7102.12.0.0/15102.12.0.1 to 102.13.255.254102.13.255.255131,070
8102.14.0.0/15102.14.0.1 to 102.15.255.254102.15.255.255131,070
9102.16.0.0/15102.16.0.1 to 102.17.255.254102.17.255.255131,070
10102.18.0.0/15102.18.0.1 to 102.19.255.254102.19.255.255131,070
11102.20.0.0/15102.20.0.1 to 102.21.255.254102.21.255.255131,070
12102.22.0.0/15102.22.0.1 to 102.23.255.254102.23.255.255131,070
13102.24.0.0/15102.24.0.1 to 102.25.255.254102.25.255.255131,070
14102.26.0.0/15102.26.0.1 to 102.27.255.254102.27.255.255131,070
15102.28.0.0/15102.28.0.1 to 102.29.255.254102.29.255.255131,070
16102.30.0.0/15102.30.0.1 to 102.31.255.254102.31.255.255131,070
17102.32.0.0/15102.32.0.1 to 102.33.255.254102.33.255.255131,070
18102.34.0.0/15102.34.0.1 to 102.35.255.254102.35.255.255131,070
19102.36.0.0/15102.36.0.1 to 102.37.255.254102.37.255.255131,070
20102.38.0.0/15102.38.0.1 to 102.39.255.254102.39.255.255131,070
21102.40.0.0/15102.40.0.1 to 102.41.255.254102.41.255.255131,070
22102.42.0.0/15102.42.0.1 to 102.43.255.254102.43.255.255131,070
23102.44.0.0/15102.44.0.1 to 102.45.255.254102.45.255.255131,070
24102.46.0.0/15102.46.0.1 to 102.47.255.254102.47.255.255131,070
25102.48.0.0/15102.48.0.1 to 102.49.255.254102.49.255.255131,070
26102.50.0.0/15102.50.0.1 to 102.51.255.254102.51.255.255131,070
27102.52.0.0/15102.52.0.1 to 102.53.255.254102.53.255.255131,070
28102.54.0.0/15102.54.0.1 to 102.55.255.254102.55.255.255131,070
29102.56.0.0/15102.56.0.1 to 102.57.255.254102.57.255.255131,070
30102.58.0.0/15102.58.0.1 to 102.59.255.254102.59.255.255131,070
31102.60.0.0/15102.60.0.1 to 102.61.255.254102.61.255.255131,070
32102.62.0.0/15102.62.0.1 to 102.63.255.254102.63.255.255131,070
33102.64.0.0/15102.64.0.1 to 102.65.255.254102.65.255.255131,070
34102.66.0.0/15102.66.0.1 to 102.67.255.254102.67.255.255131,070
35102.68.0.0/15102.68.0.1 to 102.69.255.254102.69.255.255131,070
36102.70.0.0/15102.70.0.1 to 102.71.255.254102.71.255.255131,070
37102.72.0.0/15102.72.0.1 to 102.73.255.254102.73.255.255131,070
38102.74.0.0/15102.74.0.1 to 102.75.255.254102.75.255.255131,070
39102.76.0.0/15102.76.0.1 to 102.77.255.254102.77.255.255131,070
40102.78.0.0/15102.78.0.1 to 102.79.255.254102.79.255.255131,070
41102.80.0.0/15102.80.0.1 to 102.81.255.254102.81.255.255131,070
42102.82.0.0/15102.82.0.1 to 102.83.255.254102.83.255.255131,070
43102.84.0.0/15102.84.0.1 to 102.85.255.254102.85.255.255131,070
44102.86.0.0/15102.86.0.1 to 102.87.255.254102.87.255.255131,070
45102.88.0.0/15102.88.0.1 to 102.89.255.254102.89.255.255131,070
46102.90.0.0/15102.90.0.1 to 102.91.255.254102.91.255.255131,070
47102.92.0.0/15102.92.0.1 to 102.93.255.254102.93.255.255131,070
48102.94.0.0/15102.94.0.1 to 102.95.255.254102.95.255.255131,070
49102.96.0.0/15102.96.0.1 to 102.97.255.254102.97.255.255131,070
50102.98.0.0/15102.98.0.1 to 102.99.255.254102.99.255.255131,070
51102.100.0.0/15102.100.0.1 to 102.101.255.254102.101.255.255131,070
52102.102.0.0/15102.102.0.1 to 102.103.255.254102.103.255.255131,070
53102.104.0.0/15102.104.0.1 to 102.105.255.254102.105.255.255131,070
54102.106.0.0/15102.106.0.1 to 102.107.255.254102.107.255.255131,070
55102.108.0.0/15102.108.0.1 to 102.109.255.254102.109.255.255131,070
56102.110.0.0/15102.110.0.1 to 102.111.255.254102.111.255.255131,070
57102.112.0.0/15102.112.0.1 to 102.113.255.254102.113.255.255131,070
58102.114.0.0/15102.114.0.1 to 102.115.255.254102.115.255.255131,070
59102.116.0.0/15102.116.0.1 to 102.117.255.254102.117.255.255131,070
60102.118.0.0/15102.118.0.1 to 102.119.255.254102.119.255.255131,070
61102.120.0.0/15102.120.0.1 to 102.121.255.254102.121.255.255131,070
62102.122.0.0/15102.122.0.1 to 102.123.255.254102.123.255.255131,070
63102.124.0.0/15102.124.0.1 to 102.125.255.254102.125.255.255131,070
64102.126.0.0/15102.126.0.1 to 102.127.255.254102.127.255.255131,070
65102.128.0.0/15102.128.0.1 to 102.129.255.254102.129.255.255131,070
66102.130.0.0/15102.130.0.1 to 102.131.255.254102.131.255.255131,070
67102.132.0.0/15102.132.0.1 to 102.133.255.254102.133.255.255131,070
68102.134.0.0/15102.134.0.1 to 102.135.255.254102.135.255.255131,070
69102.136.0.0/15102.136.0.1 to 102.137.255.254102.137.255.255131,070
70102.138.0.0/15102.138.0.1 to 102.139.255.254102.139.255.255131,070
71102.140.0.0/15102.140.0.1 to 102.141.255.254102.141.255.255131,070
72102.142.0.0/15102.142.0.1 to 102.143.255.254102.143.255.255131,070
73102.144.0.0/15102.144.0.1 to 102.145.255.254102.145.255.255131,070
74102.146.0.0/15102.146.0.1 to 102.147.255.254102.147.255.255131,070
75102.148.0.0/15102.148.0.1 to 102.149.255.254102.149.255.255131,070
76102.150.0.0/15102.150.0.1 to 102.151.255.254102.151.255.255131,070
77102.152.0.0/15102.152.0.1 to 102.153.255.254102.153.255.255131,070
78102.154.0.0/15102.154.0.1 to 102.155.255.254102.155.255.255131,070
79102.156.0.0/15102.156.0.1 to 102.157.255.254102.157.255.255131,070
80102.158.0.0/15102.158.0.1 to 102.159.255.254102.159.255.255131,070
81102.160.0.0/15102.160.0.1 to 102.161.255.254102.161.255.255131,070
82102.162.0.0/15102.162.0.1 to 102.163.255.254102.163.255.255131,070
83102.164.0.0/15102.164.0.1 to 102.165.255.254102.165.255.255131,070
84102.166.0.0/15102.166.0.1 to 102.167.255.254102.167.255.255131,070
85102.168.0.0/15102.168.0.1 to 102.169.255.254102.169.255.255131,070
86102.170.0.0/15102.170.0.1 to 102.171.255.254102.171.255.255131,070
87102.172.0.0/15102.172.0.1 to 102.173.255.254102.173.255.255131,070
88102.174.0.0/15102.174.0.1 to 102.175.255.254102.175.255.255131,070
89102.176.0.0/15102.176.0.1 to 102.177.255.254102.177.255.255131,070
90102.178.0.0/15102.178.0.1 to 102.179.255.254102.179.255.255131,070
91102.180.0.0/15102.180.0.1 to 102.181.255.254102.181.255.255131,070
92102.182.0.0/15102.182.0.1 to 102.183.255.254102.183.255.255131,070
93102.184.0.0/15102.184.0.1 to 102.185.255.254102.185.255.255131,070
94102.186.0.0/15102.186.0.1 to 102.187.255.254102.187.255.255131,070
95102.188.0.0/15102.188.0.1 to 102.189.255.254102.189.255.255131,070
96102.190.0.0/15102.190.0.1 to 102.191.255.254102.191.255.255131,070
97102.192.0.0/15102.192.0.1 to 102.193.255.254102.193.255.255131,070
98102.194.0.0/15102.194.0.1 to 102.195.255.254102.195.255.255131,070
99102.196.0.0/15102.196.0.1 to 102.197.255.254102.197.255.255131,070
100102.198.0.0/15102.198.0.1 to 102.199.255.254102.199.255.255131,070
101102.200.0.0/15102.200.0.1 to 102.201.255.254102.201.255.255131,070
102102.202.0.0/15102.202.0.1 to 102.203.255.254102.203.255.255131,070
103102.204.0.0/15102.204.0.1 to 102.205.255.254102.205.255.255131,070
104102.206.0.0/15102.206.0.1 to 102.207.255.254102.207.255.255131,070
105102.208.0.0/15102.208.0.1 to 102.209.255.254102.209.255.255131,070
106102.210.0.0/15102.210.0.1 to 102.211.255.254102.211.255.255131,070
107102.212.0.0/15102.212.0.1 to 102.213.255.254102.213.255.255131,070
108102.214.0.0/15102.214.0.1 to 102.215.255.254102.215.255.255131,070
109102.216.0.0/15102.216.0.1 to 102.217.255.254102.217.255.255131,070
110102.218.0.0/15102.218.0.1 to 102.219.255.254102.219.255.255131,070
111102.220.0.0/15102.220.0.1 to 102.221.255.254102.221.255.255131,070
112102.222.0.0/15102.222.0.1 to 102.223.255.254102.223.255.255131,070
113102.224.0.0/15102.224.0.1 to 102.225.255.254102.225.255.255131,070
114102.226.0.0/15102.226.0.1 to 102.227.255.254102.227.255.255131,070
115102.228.0.0/15102.228.0.1 to 102.229.255.254102.229.255.255131,070
116102.230.0.0/15102.230.0.1 to 102.231.255.254102.231.255.255131,070
117102.232.0.0/15102.232.0.1 to 102.233.255.254102.233.255.255131,070
118102.234.0.0/15102.234.0.1 to 102.235.255.254102.235.255.255131,070
119102.236.0.0/15102.236.0.1 to 102.237.255.254102.237.255.255131,070
120102.238.0.0/15102.238.0.1 to 102.239.255.254102.239.255.255131,070
121102.240.0.0/15102.240.0.1 to 102.241.255.254102.241.255.255131,070
122102.242.0.0/15102.242.0.1 to 102.243.255.254102.243.255.255131,070
123102.244.0.0/15102.244.0.1 to 102.245.255.254102.245.255.255131,070
124102.246.0.0/15102.246.0.1 to 102.247.255.254102.247.255.255131,070
125102.248.0.0/15102.248.0.1 to 102.249.255.254102.249.255.255131,070
126102.250.0.0/15102.250.0.1 to 102.251.255.254102.251.255.255131,070
127102.252.0.0/15102.252.0.1 to 102.253.255.254102.253.255.255131,070
128102.254.0.0/15102.254.0.1 to 102.255.255.254102.255.255.255131,070
129103.0.0.0/15103.0.0.1 to 103.1.255.254103.1.255.255131,070
130103.2.0.0/15103.2.0.1 to 103.3.255.254103.3.255.255131,070
131103.4.0.0/15103.4.0.1 to 103.5.255.254103.5.255.255131,070
132103.6.0.0/15103.6.0.1 to 103.7.255.254103.7.255.255131,070
133103.8.0.0/15103.8.0.1 to 103.9.255.254103.9.255.255131,070
134103.10.0.0/15103.10.0.1 to 103.11.255.254103.11.255.255131,070
135103.12.0.0/15103.12.0.1 to 103.13.255.254103.13.255.255131,070
136103.14.0.0/15103.14.0.1 to 103.15.255.254103.15.255.255131,070
137103.16.0.0/15103.16.0.1 to 103.17.255.254103.17.255.255131,070
138103.18.0.0/15103.18.0.1 to 103.19.255.254103.19.255.255131,070
139103.20.0.0/15103.20.0.1 to 103.21.255.254103.21.255.255131,070
140103.22.0.0/15103.22.0.1 to 103.23.255.254103.23.255.255131,070
141103.24.0.0/15103.24.0.1 to 103.25.255.254103.25.255.255131,070
142103.26.0.0/15103.26.0.1 to 103.27.255.254103.27.255.255131,070
143103.28.0.0/15103.28.0.1 to 103.29.255.254103.29.255.255131,070
144103.30.0.0/15103.30.0.1 to 103.31.255.254103.31.255.255131,070
145103.32.0.0/15103.32.0.1 to 103.33.255.254103.33.255.255131,070
146103.34.0.0/15103.34.0.1 to 103.35.255.254103.35.255.255131,070
147103.36.0.0/15103.36.0.1 to 103.37.255.254103.37.255.255131,070
148103.38.0.0/15103.38.0.1 to 103.39.255.254103.39.255.255131,070
149103.40.0.0/15103.40.0.1 to 103.41.255.254103.41.255.255131,070
150103.42.0.0/15103.42.0.1 to 103.43.255.254103.43.255.255131,070
151103.44.0.0/15103.44.0.1 to 103.45.255.254103.45.255.255131,070
152103.46.0.0/15103.46.0.1 to 103.47.255.254103.47.255.255131,070
153103.48.0.0/15103.48.0.1 to 103.49.255.254103.49.255.255131,070
154103.50.0.0/15103.50.0.1 to 103.51.255.254103.51.255.255131,070
155103.52.0.0/15103.52.0.1 to 103.53.255.254103.53.255.255131,070
156103.54.0.0/15103.54.0.1 to 103.55.255.254103.55.255.255131,070
157103.56.0.0/15103.56.0.1 to 103.57.255.254103.57.255.255131,070
158103.58.0.0/15103.58.0.1 to 103.59.255.254103.59.255.255131,070
159103.60.0.0/15103.60.0.1 to 103.61.255.254103.61.255.255131,070
160103.62.0.0/15103.62.0.1 to 103.63.255.254103.63.255.255131,070
161103.64.0.0/15103.64.0.1 to 103.65.255.254103.65.255.255131,070
162103.66.0.0/15103.66.0.1 to 103.67.255.254103.67.255.255131,070
163103.68.0.0/15103.68.0.1 to 103.69.255.254103.69.255.255131,070
164103.70.0.0/15103.70.0.1 to 103.71.255.254103.71.255.255131,070
165103.72.0.0/15103.72.0.1 to 103.73.255.254103.73.255.255131,070
166103.74.0.0/15103.74.0.1 to 103.75.255.254103.75.255.255131,070
167103.76.0.0/15103.76.0.1 to 103.77.255.254103.77.255.255131,070
168103.78.0.0/15103.78.0.1 to 103.79.255.254103.79.255.255131,070
169103.80.0.0/15103.80.0.1 to 103.81.255.254103.81.255.255131,070
170103.82.0.0/15103.82.0.1 to 103.83.255.254103.83.255.255131,070
171103.84.0.0/15103.84.0.1 to 103.85.255.254103.85.255.255131,070
172103.86.0.0/15103.86.0.1 to 103.87.255.254103.87.255.255131,070
173103.88.0.0/15103.88.0.1 to 103.89.255.254103.89.255.255131,070
174103.90.0.0/15103.90.0.1 to 103.91.255.254103.91.255.255131,070
175103.92.0.0/15103.92.0.1 to 103.93.255.254103.93.255.255131,070
176103.94.0.0/15103.94.0.1 to 103.95.255.254103.95.255.255131,070
177103.96.0.0/15103.96.0.1 to 103.97.255.254103.97.255.255131,070
178103.98.0.0/15103.98.0.1 to 103.99.255.254103.99.255.255131,070
179103.100.0.0/15103.100.0.1 to 103.101.255.254103.101.255.255131,070
180103.102.0.0/15103.102.0.1 to 103.103.255.254103.103.255.255131,070
181103.104.0.0/15103.104.0.1 to 103.105.255.254103.105.255.255131,070
182103.106.0.0/15103.106.0.1 to 103.107.255.254103.107.255.255131,070
183103.108.0.0/15103.108.0.1 to 103.109.255.254103.109.255.255131,070
184103.110.0.0/15103.110.0.1 to 103.111.255.254103.111.255.255131,070
185103.112.0.0/15103.112.0.1 to 103.113.255.254103.113.255.255131,070
186103.114.0.0/15103.114.0.1 to 103.115.255.254103.115.255.255131,070
187103.116.0.0/15103.116.0.1 to 103.117.255.254103.117.255.255131,070
188103.118.0.0/15103.118.0.1 to 103.119.255.254103.119.255.255131,070
189103.120.0.0/15103.120.0.1 to 103.121.255.254103.121.255.255131,070
190103.122.0.0/15103.122.0.1 to 103.123.255.254103.123.255.255131,070
191103.124.0.0/15103.124.0.1 to 103.125.255.254103.125.255.255131,070
192103.126.0.0/15103.126.0.1 to 103.127.255.254103.127.255.255131,070
193103.128.0.0/15103.128.0.1 to 103.129.255.254103.129.255.255131,070
194103.130.0.0/15103.130.0.1 to 103.131.255.254103.131.255.255131,070
195103.132.0.0/15103.132.0.1 to 103.133.255.254103.133.255.255131,070
196103.134.0.0/15103.134.0.1 to 103.135.255.254103.135.255.255131,070
197103.136.0.0/15103.136.0.1 to 103.137.255.254103.137.255.255131,070
198103.138.0.0/15103.138.0.1 to 103.139.255.254103.139.255.255131,070
199103.140.0.0/15103.140.0.1 to 103.141.255.254103.141.255.255131,070
200103.142.0.0/15103.142.0.1 to 103.143.255.254103.143.255.255131,070
201103.144.0.0/15103.144.0.1 to 103.145.255.254103.145.255.255131,070
202103.146.0.0/15103.146.0.1 to 103.147.255.254103.147.255.255131,070
203103.148.0.0/15103.148.0.1 to 103.149.255.254103.149.255.255131,070
204103.150.0.0/15103.150.0.1 to 103.151.255.254103.151.255.255131,070
205103.152.0.0/15103.152.0.1 to 103.153.255.254103.153.255.255131,070
206103.154.0.0/15103.154.0.1 to 103.155.255.254103.155.255.255131,070
207103.156.0.0/15103.156.0.1 to 103.157.255.254103.157.255.255131,070
208103.158.0.0/15103.158.0.1 to 103.159.255.254103.159.255.255131,070
209103.160.0.0/15103.160.0.1 to 103.161.255.254103.161.255.255131,070
210103.162.0.0/15103.162.0.1 to 103.163.255.254103.163.255.255131,070
211103.164.0.0/15103.164.0.1 to 103.165.255.254103.165.255.255131,070
212103.166.0.0/15103.166.0.1 to 103.167.255.254103.167.255.255131,070
213103.168.0.0/15103.168.0.1 to 103.169.255.254103.169.255.255131,070
214103.170.0.0/15103.170.0.1 to 103.171.255.254103.171.255.255131,070
215103.172.0.0/15103.172.0.1 to 103.173.255.254103.173.255.255131,070
216103.174.0.0/15103.174.0.1 to 103.175.255.254103.175.255.255131,070
217103.176.0.0/15103.176.0.1 to 103.177.255.254103.177.255.255131,070
218103.178.0.0/15103.178.0.1 to 103.179.255.254103.179.255.255131,070
219103.180.0.0/15103.180.0.1 to 103.181.255.254103.181.255.255131,070
220103.182.0.0/15103.182.0.1 to 103.183.255.254103.183.255.255131,070
221103.184.0.0/15103.184.0.1 to 103.185.255.254103.185.255.255131,070
222103.186.0.0/15103.186.0.1 to 103.187.255.254103.187.255.255131,070
223103.188.0.0/15103.188.0.1 to 103.189.255.254103.189.255.255131,070
224103.190.0.0/15103.190.0.1 to 103.191.255.254103.191.255.255131,070
225103.192.0.0/15103.192.0.1 to 103.193.255.254103.193.255.255131,070
226103.194.0.0/15103.194.0.1 to 103.195.255.254103.195.255.255131,070
227103.196.0.0/15103.196.0.1 to 103.197.255.254103.197.255.255131,070
228103.198.0.0/15103.198.0.1 to 103.199.255.254103.199.255.255131,070
229103.200.0.0/15103.200.0.1 to 103.201.255.254103.201.255.255131,070
230103.202.0.0/15103.202.0.1 to 103.203.255.254103.203.255.255131,070
231103.204.0.0/15103.204.0.1 to 103.205.255.254103.205.255.255131,070
232103.206.0.0/15103.206.0.1 to 103.207.255.254103.207.255.255131,070
233103.208.0.0/15103.208.0.1 to 103.209.255.254103.209.255.255131,070
234103.210.0.0/15103.210.0.1 to 103.211.255.254103.211.255.255131,070
235103.212.0.0/15103.212.0.1 to 103.213.255.254103.213.255.255131,070
236103.214.0.0/15103.214.0.1 to 103.215.255.254103.215.255.255131,070
237103.216.0.0/15103.216.0.1 to 103.217.255.254103.217.255.255131,070
238103.218.0.0/15103.218.0.1 to 103.219.255.254103.219.255.255131,070
239103.220.0.0/15103.220.0.1 to 103.221.255.254103.221.255.255131,070
240103.222.0.0/15103.222.0.1 to 103.223.255.254103.223.255.255131,070
241103.224.0.0/15103.224.0.1 to 103.225.255.254103.225.255.255131,070
242103.226.0.0/15103.226.0.1 to 103.227.255.254103.227.255.255131,070
243103.228.0.0/15103.228.0.1 to 103.229.255.254103.229.255.255131,070
244103.230.0.0/15103.230.0.1 to 103.231.255.254103.231.255.255131,070
245103.232.0.0/15103.232.0.1 to 103.233.255.254103.233.255.255131,070
246103.234.0.0/15103.234.0.1 to 103.235.255.254103.235.255.255131,070
247103.236.0.0/15103.236.0.1 to 103.237.255.254103.237.255.255131,070
248103.238.0.0/15103.238.0.1 to 103.239.255.254103.239.255.255131,070
249103.240.0.0/15103.240.0.1 to 103.241.255.254103.241.255.255131,070
250103.242.0.0/15103.242.0.1 to 103.243.255.254103.243.255.255131,070
251103.244.0.0/15103.244.0.1 to 103.245.255.254103.245.255.255131,070
252103.246.0.0/15103.246.0.1 to 103.247.255.254103.247.255.255131,070
253103.248.0.0/15103.248.0.1 to 103.249.255.254103.249.255.255131,070
254103.250.0.0/15103.250.0.1 to 103.251.255.254103.251.255.255131,070
255103.252.0.0/15103.252.0.1 to 103.253.255.254103.253.255.255131,070
256103.254.0.0/15103.254.0.1 to 103.255.255.254103.255.255.255131,070

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic 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.