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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.

Network248.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
248.0.0.0
Broadcast address
249.255.255.255
First usable
248.0.0.1
Last usable
249.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F8000000 · Integer 4160749568 to 4194303999
Reverse DNS zones
248.in-addr.arpa
249.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
Address11111000.00000000.00000000.00000000248.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11111000.00000000.00000000.00000000248.0.0.0
Broadcast11111001.11111111.11111111.11111111249.255.255.255
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)

248.0.0.0/7 makes 256 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1248.0.0.0/15248.0.0.1 to 248.1.255.254248.1.255.255131,070
2248.2.0.0/15248.2.0.1 to 248.3.255.254248.3.255.255131,070
3248.4.0.0/15248.4.0.1 to 248.5.255.254248.5.255.255131,070
4248.6.0.0/15248.6.0.1 to 248.7.255.254248.7.255.255131,070
5248.8.0.0/15248.8.0.1 to 248.9.255.254248.9.255.255131,070
6248.10.0.0/15248.10.0.1 to 248.11.255.254248.11.255.255131,070
7248.12.0.0/15248.12.0.1 to 248.13.255.254248.13.255.255131,070
8248.14.0.0/15248.14.0.1 to 248.15.255.254248.15.255.255131,070
9248.16.0.0/15248.16.0.1 to 248.17.255.254248.17.255.255131,070
10248.18.0.0/15248.18.0.1 to 248.19.255.254248.19.255.255131,070
11248.20.0.0/15248.20.0.1 to 248.21.255.254248.21.255.255131,070
12248.22.0.0/15248.22.0.1 to 248.23.255.254248.23.255.255131,070
13248.24.0.0/15248.24.0.1 to 248.25.255.254248.25.255.255131,070
14248.26.0.0/15248.26.0.1 to 248.27.255.254248.27.255.255131,070
15248.28.0.0/15248.28.0.1 to 248.29.255.254248.29.255.255131,070
16248.30.0.0/15248.30.0.1 to 248.31.255.254248.31.255.255131,070
17248.32.0.0/15248.32.0.1 to 248.33.255.254248.33.255.255131,070
18248.34.0.0/15248.34.0.1 to 248.35.255.254248.35.255.255131,070
19248.36.0.0/15248.36.0.1 to 248.37.255.254248.37.255.255131,070
20248.38.0.0/15248.38.0.1 to 248.39.255.254248.39.255.255131,070
21248.40.0.0/15248.40.0.1 to 248.41.255.254248.41.255.255131,070
22248.42.0.0/15248.42.0.1 to 248.43.255.254248.43.255.255131,070
23248.44.0.0/15248.44.0.1 to 248.45.255.254248.45.255.255131,070
24248.46.0.0/15248.46.0.1 to 248.47.255.254248.47.255.255131,070
25248.48.0.0/15248.48.0.1 to 248.49.255.254248.49.255.255131,070
26248.50.0.0/15248.50.0.1 to 248.51.255.254248.51.255.255131,070
27248.52.0.0/15248.52.0.1 to 248.53.255.254248.53.255.255131,070
28248.54.0.0/15248.54.0.1 to 248.55.255.254248.55.255.255131,070
29248.56.0.0/15248.56.0.1 to 248.57.255.254248.57.255.255131,070
30248.58.0.0/15248.58.0.1 to 248.59.255.254248.59.255.255131,070
31248.60.0.0/15248.60.0.1 to 248.61.255.254248.61.255.255131,070
32248.62.0.0/15248.62.0.1 to 248.63.255.254248.63.255.255131,070
33248.64.0.0/15248.64.0.1 to 248.65.255.254248.65.255.255131,070
34248.66.0.0/15248.66.0.1 to 248.67.255.254248.67.255.255131,070
35248.68.0.0/15248.68.0.1 to 248.69.255.254248.69.255.255131,070
36248.70.0.0/15248.70.0.1 to 248.71.255.254248.71.255.255131,070
37248.72.0.0/15248.72.0.1 to 248.73.255.254248.73.255.255131,070
38248.74.0.0/15248.74.0.1 to 248.75.255.254248.75.255.255131,070
39248.76.0.0/15248.76.0.1 to 248.77.255.254248.77.255.255131,070
40248.78.0.0/15248.78.0.1 to 248.79.255.254248.79.255.255131,070
41248.80.0.0/15248.80.0.1 to 248.81.255.254248.81.255.255131,070
42248.82.0.0/15248.82.0.1 to 248.83.255.254248.83.255.255131,070
43248.84.0.0/15248.84.0.1 to 248.85.255.254248.85.255.255131,070
44248.86.0.0/15248.86.0.1 to 248.87.255.254248.87.255.255131,070
45248.88.0.0/15248.88.0.1 to 248.89.255.254248.89.255.255131,070
46248.90.0.0/15248.90.0.1 to 248.91.255.254248.91.255.255131,070
47248.92.0.0/15248.92.0.1 to 248.93.255.254248.93.255.255131,070
48248.94.0.0/15248.94.0.1 to 248.95.255.254248.95.255.255131,070
49248.96.0.0/15248.96.0.1 to 248.97.255.254248.97.255.255131,070
50248.98.0.0/15248.98.0.1 to 248.99.255.254248.99.255.255131,070
51248.100.0.0/15248.100.0.1 to 248.101.255.254248.101.255.255131,070
52248.102.0.0/15248.102.0.1 to 248.103.255.254248.103.255.255131,070
53248.104.0.0/15248.104.0.1 to 248.105.255.254248.105.255.255131,070
54248.106.0.0/15248.106.0.1 to 248.107.255.254248.107.255.255131,070
55248.108.0.0/15248.108.0.1 to 248.109.255.254248.109.255.255131,070
56248.110.0.0/15248.110.0.1 to 248.111.255.254248.111.255.255131,070
57248.112.0.0/15248.112.0.1 to 248.113.255.254248.113.255.255131,070
58248.114.0.0/15248.114.0.1 to 248.115.255.254248.115.255.255131,070
59248.116.0.0/15248.116.0.1 to 248.117.255.254248.117.255.255131,070
60248.118.0.0/15248.118.0.1 to 248.119.255.254248.119.255.255131,070
61248.120.0.0/15248.120.0.1 to 248.121.255.254248.121.255.255131,070
62248.122.0.0/15248.122.0.1 to 248.123.255.254248.123.255.255131,070
63248.124.0.0/15248.124.0.1 to 248.125.255.254248.125.255.255131,070
64248.126.0.0/15248.126.0.1 to 248.127.255.254248.127.255.255131,070
65248.128.0.0/15248.128.0.1 to 248.129.255.254248.129.255.255131,070
66248.130.0.0/15248.130.0.1 to 248.131.255.254248.131.255.255131,070
67248.132.0.0/15248.132.0.1 to 248.133.255.254248.133.255.255131,070
68248.134.0.0/15248.134.0.1 to 248.135.255.254248.135.255.255131,070
69248.136.0.0/15248.136.0.1 to 248.137.255.254248.137.255.255131,070
70248.138.0.0/15248.138.0.1 to 248.139.255.254248.139.255.255131,070
71248.140.0.0/15248.140.0.1 to 248.141.255.254248.141.255.255131,070
72248.142.0.0/15248.142.0.1 to 248.143.255.254248.143.255.255131,070
73248.144.0.0/15248.144.0.1 to 248.145.255.254248.145.255.255131,070
74248.146.0.0/15248.146.0.1 to 248.147.255.254248.147.255.255131,070
75248.148.0.0/15248.148.0.1 to 248.149.255.254248.149.255.255131,070
76248.150.0.0/15248.150.0.1 to 248.151.255.254248.151.255.255131,070
77248.152.0.0/15248.152.0.1 to 248.153.255.254248.153.255.255131,070
78248.154.0.0/15248.154.0.1 to 248.155.255.254248.155.255.255131,070
79248.156.0.0/15248.156.0.1 to 248.157.255.254248.157.255.255131,070
80248.158.0.0/15248.158.0.1 to 248.159.255.254248.159.255.255131,070
81248.160.0.0/15248.160.0.1 to 248.161.255.254248.161.255.255131,070
82248.162.0.0/15248.162.0.1 to 248.163.255.254248.163.255.255131,070
83248.164.0.0/15248.164.0.1 to 248.165.255.254248.165.255.255131,070
84248.166.0.0/15248.166.0.1 to 248.167.255.254248.167.255.255131,070
85248.168.0.0/15248.168.0.1 to 248.169.255.254248.169.255.255131,070
86248.170.0.0/15248.170.0.1 to 248.171.255.254248.171.255.255131,070
87248.172.0.0/15248.172.0.1 to 248.173.255.254248.173.255.255131,070
88248.174.0.0/15248.174.0.1 to 248.175.255.254248.175.255.255131,070
89248.176.0.0/15248.176.0.1 to 248.177.255.254248.177.255.255131,070
90248.178.0.0/15248.178.0.1 to 248.179.255.254248.179.255.255131,070
91248.180.0.0/15248.180.0.1 to 248.181.255.254248.181.255.255131,070
92248.182.0.0/15248.182.0.1 to 248.183.255.254248.183.255.255131,070
93248.184.0.0/15248.184.0.1 to 248.185.255.254248.185.255.255131,070
94248.186.0.0/15248.186.0.1 to 248.187.255.254248.187.255.255131,070
95248.188.0.0/15248.188.0.1 to 248.189.255.254248.189.255.255131,070
96248.190.0.0/15248.190.0.1 to 248.191.255.254248.191.255.255131,070
97248.192.0.0/15248.192.0.1 to 248.193.255.254248.193.255.255131,070
98248.194.0.0/15248.194.0.1 to 248.195.255.254248.195.255.255131,070
99248.196.0.0/15248.196.0.1 to 248.197.255.254248.197.255.255131,070
100248.198.0.0/15248.198.0.1 to 248.199.255.254248.199.255.255131,070
101248.200.0.0/15248.200.0.1 to 248.201.255.254248.201.255.255131,070
102248.202.0.0/15248.202.0.1 to 248.203.255.254248.203.255.255131,070
103248.204.0.0/15248.204.0.1 to 248.205.255.254248.205.255.255131,070
104248.206.0.0/15248.206.0.1 to 248.207.255.254248.207.255.255131,070
105248.208.0.0/15248.208.0.1 to 248.209.255.254248.209.255.255131,070
106248.210.0.0/15248.210.0.1 to 248.211.255.254248.211.255.255131,070
107248.212.0.0/15248.212.0.1 to 248.213.255.254248.213.255.255131,070
108248.214.0.0/15248.214.0.1 to 248.215.255.254248.215.255.255131,070
109248.216.0.0/15248.216.0.1 to 248.217.255.254248.217.255.255131,070
110248.218.0.0/15248.218.0.1 to 248.219.255.254248.219.255.255131,070
111248.220.0.0/15248.220.0.1 to 248.221.255.254248.221.255.255131,070
112248.222.0.0/15248.222.0.1 to 248.223.255.254248.223.255.255131,070
113248.224.0.0/15248.224.0.1 to 248.225.255.254248.225.255.255131,070
114248.226.0.0/15248.226.0.1 to 248.227.255.254248.227.255.255131,070
115248.228.0.0/15248.228.0.1 to 248.229.255.254248.229.255.255131,070
116248.230.0.0/15248.230.0.1 to 248.231.255.254248.231.255.255131,070
117248.232.0.0/15248.232.0.1 to 248.233.255.254248.233.255.255131,070
118248.234.0.0/15248.234.0.1 to 248.235.255.254248.235.255.255131,070
119248.236.0.0/15248.236.0.1 to 248.237.255.254248.237.255.255131,070
120248.238.0.0/15248.238.0.1 to 248.239.255.254248.239.255.255131,070
121248.240.0.0/15248.240.0.1 to 248.241.255.254248.241.255.255131,070
122248.242.0.0/15248.242.0.1 to 248.243.255.254248.243.255.255131,070
123248.244.0.0/15248.244.0.1 to 248.245.255.254248.245.255.255131,070
124248.246.0.0/15248.246.0.1 to 248.247.255.254248.247.255.255131,070
125248.248.0.0/15248.248.0.1 to 248.249.255.254248.249.255.255131,070
126248.250.0.0/15248.250.0.1 to 248.251.255.254248.251.255.255131,070
127248.252.0.0/15248.252.0.1 to 248.253.255.254248.253.255.255131,070
128248.254.0.0/15248.254.0.1 to 248.255.255.254248.255.255.255131,070
129249.0.0.0/15249.0.0.1 to 249.1.255.254249.1.255.255131,070
130249.2.0.0/15249.2.0.1 to 249.3.255.254249.3.255.255131,070
131249.4.0.0/15249.4.0.1 to 249.5.255.254249.5.255.255131,070
132249.6.0.0/15249.6.0.1 to 249.7.255.254249.7.255.255131,070
133249.8.0.0/15249.8.0.1 to 249.9.255.254249.9.255.255131,070
134249.10.0.0/15249.10.0.1 to 249.11.255.254249.11.255.255131,070
135249.12.0.0/15249.12.0.1 to 249.13.255.254249.13.255.255131,070
136249.14.0.0/15249.14.0.1 to 249.15.255.254249.15.255.255131,070
137249.16.0.0/15249.16.0.1 to 249.17.255.254249.17.255.255131,070
138249.18.0.0/15249.18.0.1 to 249.19.255.254249.19.255.255131,070
139249.20.0.0/15249.20.0.1 to 249.21.255.254249.21.255.255131,070
140249.22.0.0/15249.22.0.1 to 249.23.255.254249.23.255.255131,070
141249.24.0.0/15249.24.0.1 to 249.25.255.254249.25.255.255131,070
142249.26.0.0/15249.26.0.1 to 249.27.255.254249.27.255.255131,070
143249.28.0.0/15249.28.0.1 to 249.29.255.254249.29.255.255131,070
144249.30.0.0/15249.30.0.1 to 249.31.255.254249.31.255.255131,070
145249.32.0.0/15249.32.0.1 to 249.33.255.254249.33.255.255131,070
146249.34.0.0/15249.34.0.1 to 249.35.255.254249.35.255.255131,070
147249.36.0.0/15249.36.0.1 to 249.37.255.254249.37.255.255131,070
148249.38.0.0/15249.38.0.1 to 249.39.255.254249.39.255.255131,070
149249.40.0.0/15249.40.0.1 to 249.41.255.254249.41.255.255131,070
150249.42.0.0/15249.42.0.1 to 249.43.255.254249.43.255.255131,070
151249.44.0.0/15249.44.0.1 to 249.45.255.254249.45.255.255131,070
152249.46.0.0/15249.46.0.1 to 249.47.255.254249.47.255.255131,070
153249.48.0.0/15249.48.0.1 to 249.49.255.254249.49.255.255131,070
154249.50.0.0/15249.50.0.1 to 249.51.255.254249.51.255.255131,070
155249.52.0.0/15249.52.0.1 to 249.53.255.254249.53.255.255131,070
156249.54.0.0/15249.54.0.1 to 249.55.255.254249.55.255.255131,070
157249.56.0.0/15249.56.0.1 to 249.57.255.254249.57.255.255131,070
158249.58.0.0/15249.58.0.1 to 249.59.255.254249.59.255.255131,070
159249.60.0.0/15249.60.0.1 to 249.61.255.254249.61.255.255131,070
160249.62.0.0/15249.62.0.1 to 249.63.255.254249.63.255.255131,070
161249.64.0.0/15249.64.0.1 to 249.65.255.254249.65.255.255131,070
162249.66.0.0/15249.66.0.1 to 249.67.255.254249.67.255.255131,070
163249.68.0.0/15249.68.0.1 to 249.69.255.254249.69.255.255131,070
164249.70.0.0/15249.70.0.1 to 249.71.255.254249.71.255.255131,070
165249.72.0.0/15249.72.0.1 to 249.73.255.254249.73.255.255131,070
166249.74.0.0/15249.74.0.1 to 249.75.255.254249.75.255.255131,070
167249.76.0.0/15249.76.0.1 to 249.77.255.254249.77.255.255131,070
168249.78.0.0/15249.78.0.1 to 249.79.255.254249.79.255.255131,070
169249.80.0.0/15249.80.0.1 to 249.81.255.254249.81.255.255131,070
170249.82.0.0/15249.82.0.1 to 249.83.255.254249.83.255.255131,070
171249.84.0.0/15249.84.0.1 to 249.85.255.254249.85.255.255131,070
172249.86.0.0/15249.86.0.1 to 249.87.255.254249.87.255.255131,070
173249.88.0.0/15249.88.0.1 to 249.89.255.254249.89.255.255131,070
174249.90.0.0/15249.90.0.1 to 249.91.255.254249.91.255.255131,070
175249.92.0.0/15249.92.0.1 to 249.93.255.254249.93.255.255131,070
176249.94.0.0/15249.94.0.1 to 249.95.255.254249.95.255.255131,070
177249.96.0.0/15249.96.0.1 to 249.97.255.254249.97.255.255131,070
178249.98.0.0/15249.98.0.1 to 249.99.255.254249.99.255.255131,070
179249.100.0.0/15249.100.0.1 to 249.101.255.254249.101.255.255131,070
180249.102.0.0/15249.102.0.1 to 249.103.255.254249.103.255.255131,070
181249.104.0.0/15249.104.0.1 to 249.105.255.254249.105.255.255131,070
182249.106.0.0/15249.106.0.1 to 249.107.255.254249.107.255.255131,070
183249.108.0.0/15249.108.0.1 to 249.109.255.254249.109.255.255131,070
184249.110.0.0/15249.110.0.1 to 249.111.255.254249.111.255.255131,070
185249.112.0.0/15249.112.0.1 to 249.113.255.254249.113.255.255131,070
186249.114.0.0/15249.114.0.1 to 249.115.255.254249.115.255.255131,070
187249.116.0.0/15249.116.0.1 to 249.117.255.254249.117.255.255131,070
188249.118.0.0/15249.118.0.1 to 249.119.255.254249.119.255.255131,070
189249.120.0.0/15249.120.0.1 to 249.121.255.254249.121.255.255131,070
190249.122.0.0/15249.122.0.1 to 249.123.255.254249.123.255.255131,070
191249.124.0.0/15249.124.0.1 to 249.125.255.254249.125.255.255131,070
192249.126.0.0/15249.126.0.1 to 249.127.255.254249.127.255.255131,070
193249.128.0.0/15249.128.0.1 to 249.129.255.254249.129.255.255131,070
194249.130.0.0/15249.130.0.1 to 249.131.255.254249.131.255.255131,070
195249.132.0.0/15249.132.0.1 to 249.133.255.254249.133.255.255131,070
196249.134.0.0/15249.134.0.1 to 249.135.255.254249.135.255.255131,070
197249.136.0.0/15249.136.0.1 to 249.137.255.254249.137.255.255131,070
198249.138.0.0/15249.138.0.1 to 249.139.255.254249.139.255.255131,070
199249.140.0.0/15249.140.0.1 to 249.141.255.254249.141.255.255131,070
200249.142.0.0/15249.142.0.1 to 249.143.255.254249.143.255.255131,070
201249.144.0.0/15249.144.0.1 to 249.145.255.254249.145.255.255131,070
202249.146.0.0/15249.146.0.1 to 249.147.255.254249.147.255.255131,070
203249.148.0.0/15249.148.0.1 to 249.149.255.254249.149.255.255131,070
204249.150.0.0/15249.150.0.1 to 249.151.255.254249.151.255.255131,070
205249.152.0.0/15249.152.0.1 to 249.153.255.254249.153.255.255131,070
206249.154.0.0/15249.154.0.1 to 249.155.255.254249.155.255.255131,070
207249.156.0.0/15249.156.0.1 to 249.157.255.254249.157.255.255131,070
208249.158.0.0/15249.158.0.1 to 249.159.255.254249.159.255.255131,070
209249.160.0.0/15249.160.0.1 to 249.161.255.254249.161.255.255131,070
210249.162.0.0/15249.162.0.1 to 249.163.255.254249.163.255.255131,070
211249.164.0.0/15249.164.0.1 to 249.165.255.254249.165.255.255131,070
212249.166.0.0/15249.166.0.1 to 249.167.255.254249.167.255.255131,070
213249.168.0.0/15249.168.0.1 to 249.169.255.254249.169.255.255131,070
214249.170.0.0/15249.170.0.1 to 249.171.255.254249.171.255.255131,070
215249.172.0.0/15249.172.0.1 to 249.173.255.254249.173.255.255131,070
216249.174.0.0/15249.174.0.1 to 249.175.255.254249.175.255.255131,070
217249.176.0.0/15249.176.0.1 to 249.177.255.254249.177.255.255131,070
218249.178.0.0/15249.178.0.1 to 249.179.255.254249.179.255.255131,070
219249.180.0.0/15249.180.0.1 to 249.181.255.254249.181.255.255131,070
220249.182.0.0/15249.182.0.1 to 249.183.255.254249.183.255.255131,070
221249.184.0.0/15249.184.0.1 to 249.185.255.254249.185.255.255131,070
222249.186.0.0/15249.186.0.1 to 249.187.255.254249.187.255.255131,070
223249.188.0.0/15249.188.0.1 to 249.189.255.254249.189.255.255131,070
224249.190.0.0/15249.190.0.1 to 249.191.255.254249.191.255.255131,070
225249.192.0.0/15249.192.0.1 to 249.193.255.254249.193.255.255131,070
226249.194.0.0/15249.194.0.1 to 249.195.255.254249.195.255.255131,070
227249.196.0.0/15249.196.0.1 to 249.197.255.254249.197.255.255131,070
228249.198.0.0/15249.198.0.1 to 249.199.255.254249.199.255.255131,070
229249.200.0.0/15249.200.0.1 to 249.201.255.254249.201.255.255131,070
230249.202.0.0/15249.202.0.1 to 249.203.255.254249.203.255.255131,070
231249.204.0.0/15249.204.0.1 to 249.205.255.254249.205.255.255131,070
232249.206.0.0/15249.206.0.1 to 249.207.255.254249.207.255.255131,070
233249.208.0.0/15249.208.0.1 to 249.209.255.254249.209.255.255131,070
234249.210.0.0/15249.210.0.1 to 249.211.255.254249.211.255.255131,070
235249.212.0.0/15249.212.0.1 to 249.213.255.254249.213.255.255131,070
236249.214.0.0/15249.214.0.1 to 249.215.255.254249.215.255.255131,070
237249.216.0.0/15249.216.0.1 to 249.217.255.254249.217.255.255131,070
238249.218.0.0/15249.218.0.1 to 249.219.255.254249.219.255.255131,070
239249.220.0.0/15249.220.0.1 to 249.221.255.254249.221.255.255131,070
240249.222.0.0/15249.222.0.1 to 249.223.255.254249.223.255.255131,070
241249.224.0.0/15249.224.0.1 to 249.225.255.254249.225.255.255131,070
242249.226.0.0/15249.226.0.1 to 249.227.255.254249.227.255.255131,070
243249.228.0.0/15249.228.0.1 to 249.229.255.254249.229.255.255131,070
244249.230.0.0/15249.230.0.1 to 249.231.255.254249.231.255.255131,070
245249.232.0.0/15249.232.0.1 to 249.233.255.254249.233.255.255131,070
246249.234.0.0/15249.234.0.1 to 249.235.255.254249.235.255.255131,070
247249.236.0.0/15249.236.0.1 to 249.237.255.254249.237.255.255131,070
248249.238.0.0/15249.238.0.1 to 249.239.255.254249.239.255.255131,070
249249.240.0.0/15249.240.0.1 to 249.241.255.254249.241.255.255131,070
250249.242.0.0/15249.242.0.1 to 249.243.255.254249.243.255.255131,070
251249.244.0.0/15249.244.0.1 to 249.245.255.254249.245.255.255131,070
252249.246.0.0/15249.246.0.1 to 249.247.255.254249.247.255.255131,070
253249.248.0.0/15249.248.0.1 to 249.249.255.254249.249.255.255131,070
254249.250.0.0/15249.250.0.1 to 249.251.255.254249.251.255.255131,070
255249.252.0.0/15249.252.0.1 to 249.253.255.254249.253.255.255131,070
256249.254.0.0/15249.254.0.1 to 249.255.255.254249.255.255.255131,070

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.