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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.

Network26.167.136.0/21
Usable hosts2,046
Subnet mask255.255.248.0
Addresses2,048
Network address
26.167.136.0
Broadcast address
26.167.143.255
First usable
26.167.136.1
Last usable
26.167.143.254
Usable hosts
2,046 (2,048 less the network and broadcast addresses)
Subnet mask
255.255.248.0
Wildcard mask
0.0.7.255 (Cisco ACLs, OSPF)
Prefix length
/21
Type
Public public
Old class
A (default /8)
As numbers
Hex 1AA78800 · Integer 447186944 to 447188991
Reverse DNS zones
136.167.26.in-addr.arpa
137.167.26.in-addr.arpa
138.167.26.in-addr.arpa
139.167.26.in-addr.arpa
140.167.26.in-addr.arpa
141.167.26.in-addr.arpa
142.167.26.in-addr.arpa
143.167.26.in-addr.arpa
/21 is not on a 8-bit boundary, so it takes 8 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011010.10100111.10001000.0000000026.167.136.0
Subnet mask11111111.11111111.11111000.00000000255.255.248.0
Network00011010.10100111.10001000.0000000026.167.136.0
Broadcast00011010.10100111.10001111.1111111126.167.143.255
Split into smaller subnets/31
/22 (2)/23 (4)/24 (8)/25 (16)/26 (32)/27 (64)/28 (128)/29 (256)/30 (512)/31 (1,024)/32 (2,048)

26.167.136.0/21 makes 1,024 subnets of /31; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
126.167.136.0/3126.167.136.0 to 26.167.136.1—2
226.167.136.2/3126.167.136.2 to 26.167.136.3—2
326.167.136.4/3126.167.136.4 to 26.167.136.5—2
426.167.136.6/3126.167.136.6 to 26.167.136.7—2
526.167.136.8/3126.167.136.8 to 26.167.136.9—2
626.167.136.10/3126.167.136.10 to 26.167.136.11—2
726.167.136.12/3126.167.136.12 to 26.167.136.13—2
826.167.136.14/3126.167.136.14 to 26.167.136.15—2
926.167.136.16/3126.167.136.16 to 26.167.136.17—2
1026.167.136.18/3126.167.136.18 to 26.167.136.19—2
1126.167.136.20/3126.167.136.20 to 26.167.136.21—2
1226.167.136.22/3126.167.136.22 to 26.167.136.23—2
1326.167.136.24/3126.167.136.24 to 26.167.136.25—2
1426.167.136.26/3126.167.136.26 to 26.167.136.27—2
1526.167.136.28/3126.167.136.28 to 26.167.136.29—2
1626.167.136.30/3126.167.136.30 to 26.167.136.31—2
1726.167.136.32/3126.167.136.32 to 26.167.136.33—2
1826.167.136.34/3126.167.136.34 to 26.167.136.35—2
1926.167.136.36/3126.167.136.36 to 26.167.136.37—2
2026.167.136.38/3126.167.136.38 to 26.167.136.39—2
2126.167.136.40/3126.167.136.40 to 26.167.136.41—2
2226.167.136.42/3126.167.136.42 to 26.167.136.43—2
2326.167.136.44/3126.167.136.44 to 26.167.136.45—2
2426.167.136.46/3126.167.136.46 to 26.167.136.47—2
2526.167.136.48/3126.167.136.48 to 26.167.136.49—2
2626.167.136.50/3126.167.136.50 to 26.167.136.51—2
2726.167.136.52/3126.167.136.52 to 26.167.136.53—2
2826.167.136.54/3126.167.136.54 to 26.167.136.55—2
2926.167.136.56/3126.167.136.56 to 26.167.136.57—2
3026.167.136.58/3126.167.136.58 to 26.167.136.59—2
3126.167.136.60/3126.167.136.60 to 26.167.136.61—2
3226.167.136.62/3126.167.136.62 to 26.167.136.63—2
3326.167.136.64/3126.167.136.64 to 26.167.136.65—2
3426.167.136.66/3126.167.136.66 to 26.167.136.67—2
3526.167.136.68/3126.167.136.68 to 26.167.136.69—2
3626.167.136.70/3126.167.136.70 to 26.167.136.71—2
3726.167.136.72/3126.167.136.72 to 26.167.136.73—2
3826.167.136.74/3126.167.136.74 to 26.167.136.75—2
3926.167.136.76/3126.167.136.76 to 26.167.136.77—2
4026.167.136.78/3126.167.136.78 to 26.167.136.79—2
4126.167.136.80/3126.167.136.80 to 26.167.136.81—2
4226.167.136.82/3126.167.136.82 to 26.167.136.83—2
4326.167.136.84/3126.167.136.84 to 26.167.136.85—2
4426.167.136.86/3126.167.136.86 to 26.167.136.87—2
4526.167.136.88/3126.167.136.88 to 26.167.136.89—2
4626.167.136.90/3126.167.136.90 to 26.167.136.91—2
4726.167.136.92/3126.167.136.92 to 26.167.136.93—2
4826.167.136.94/3126.167.136.94 to 26.167.136.95—2
4926.167.136.96/3126.167.136.96 to 26.167.136.97—2
5026.167.136.98/3126.167.136.98 to 26.167.136.99—2
5126.167.136.100/3126.167.136.100 to 26.167.136.101—2
5226.167.136.102/3126.167.136.102 to 26.167.136.103—2
5326.167.136.104/3126.167.136.104 to 26.167.136.105—2
5426.167.136.106/3126.167.136.106 to 26.167.136.107—2
5526.167.136.108/3126.167.136.108 to 26.167.136.109—2
5626.167.136.110/3126.167.136.110 to 26.167.136.111—2
5726.167.136.112/3126.167.136.112 to 26.167.136.113—2
5826.167.136.114/3126.167.136.114 to 26.167.136.115—2
5926.167.136.116/3126.167.136.116 to 26.167.136.117—2
6026.167.136.118/3126.167.136.118 to 26.167.136.119—2
6126.167.136.120/3126.167.136.120 to 26.167.136.121—2
6226.167.136.122/3126.167.136.122 to 26.167.136.123—2
6326.167.136.124/3126.167.136.124 to 26.167.136.125—2
6426.167.136.126/3126.167.136.126 to 26.167.136.127—2
6526.167.136.128/3126.167.136.128 to 26.167.136.129—2
6626.167.136.130/3126.167.136.130 to 26.167.136.131—2
6726.167.136.132/3126.167.136.132 to 26.167.136.133—2
6826.167.136.134/3126.167.136.134 to 26.167.136.135—2
6926.167.136.136/3126.167.136.136 to 26.167.136.137—2
7026.167.136.138/3126.167.136.138 to 26.167.136.139—2
7126.167.136.140/3126.167.136.140 to 26.167.136.141—2
7226.167.136.142/3126.167.136.142 to 26.167.136.143—2
7326.167.136.144/3126.167.136.144 to 26.167.136.145—2
7426.167.136.146/3126.167.136.146 to 26.167.136.147—2
7526.167.136.148/3126.167.136.148 to 26.167.136.149—2
7626.167.136.150/3126.167.136.150 to 26.167.136.151—2
7726.167.136.152/3126.167.136.152 to 26.167.136.153—2
7826.167.136.154/3126.167.136.154 to 26.167.136.155—2
7926.167.136.156/3126.167.136.156 to 26.167.136.157—2
8026.167.136.158/3126.167.136.158 to 26.167.136.159—2
8126.167.136.160/3126.167.136.160 to 26.167.136.161—2
8226.167.136.162/3126.167.136.162 to 26.167.136.163—2
8326.167.136.164/3126.167.136.164 to 26.167.136.165—2
8426.167.136.166/3126.167.136.166 to 26.167.136.167—2
8526.167.136.168/3126.167.136.168 to 26.167.136.169—2
8626.167.136.170/3126.167.136.170 to 26.167.136.171—2
8726.167.136.172/3126.167.136.172 to 26.167.136.173—2
8826.167.136.174/3126.167.136.174 to 26.167.136.175—2
8926.167.136.176/3126.167.136.176 to 26.167.136.177—2
9026.167.136.178/3126.167.136.178 to 26.167.136.179—2
9126.167.136.180/3126.167.136.180 to 26.167.136.181—2
9226.167.136.182/3126.167.136.182 to 26.167.136.183—2
9326.167.136.184/3126.167.136.184 to 26.167.136.185—2
9426.167.136.186/3126.167.136.186 to 26.167.136.187—2
9526.167.136.188/3126.167.136.188 to 26.167.136.189—2
9626.167.136.190/3126.167.136.190 to 26.167.136.191—2
9726.167.136.192/3126.167.136.192 to 26.167.136.193—2
9826.167.136.194/3126.167.136.194 to 26.167.136.195—2
9926.167.136.196/3126.167.136.196 to 26.167.136.197—2
10026.167.136.198/3126.167.136.198 to 26.167.136.199—2
10126.167.136.200/3126.167.136.200 to 26.167.136.201—2
10226.167.136.202/3126.167.136.202 to 26.167.136.203—2
10326.167.136.204/3126.167.136.204 to 26.167.136.205—2
10426.167.136.206/3126.167.136.206 to 26.167.136.207—2
10526.167.136.208/3126.167.136.208 to 26.167.136.209—2
10626.167.136.210/3126.167.136.210 to 26.167.136.211—2
10726.167.136.212/3126.167.136.212 to 26.167.136.213—2
10826.167.136.214/3126.167.136.214 to 26.167.136.215—2
10926.167.136.216/3126.167.136.216 to 26.167.136.217—2
11026.167.136.218/3126.167.136.218 to 26.167.136.219—2
11126.167.136.220/3126.167.136.220 to 26.167.136.221—2
11226.167.136.222/3126.167.136.222 to 26.167.136.223—2
11326.167.136.224/3126.167.136.224 to 26.167.136.225—2
11426.167.136.226/3126.167.136.226 to 26.167.136.227—2
11526.167.136.228/3126.167.136.228 to 26.167.136.229—2
11626.167.136.230/3126.167.136.230 to 26.167.136.231—2
11726.167.136.232/3126.167.136.232 to 26.167.136.233—2
11826.167.136.234/3126.167.136.234 to 26.167.136.235—2
11926.167.136.236/3126.167.136.236 to 26.167.136.237—2
12026.167.136.238/3126.167.136.238 to 26.167.136.239—2
12126.167.136.240/3126.167.136.240 to 26.167.136.241—2
12226.167.136.242/3126.167.136.242 to 26.167.136.243—2
12326.167.136.244/3126.167.136.244 to 26.167.136.245—2
12426.167.136.246/3126.167.136.246 to 26.167.136.247—2
12526.167.136.248/3126.167.136.248 to 26.167.136.249—2
12626.167.136.250/3126.167.136.250 to 26.167.136.251—2
12726.167.136.252/3126.167.136.252 to 26.167.136.253—2
12826.167.136.254/3126.167.136.254 to 26.167.136.255—2
12926.167.137.0/3126.167.137.0 to 26.167.137.1—2
13026.167.137.2/3126.167.137.2 to 26.167.137.3—2
13126.167.137.4/3126.167.137.4 to 26.167.137.5—2
13226.167.137.6/3126.167.137.6 to 26.167.137.7—2
13326.167.137.8/3126.167.137.8 to 26.167.137.9—2
13426.167.137.10/3126.167.137.10 to 26.167.137.11—2
13526.167.137.12/3126.167.137.12 to 26.167.137.13—2
13626.167.137.14/3126.167.137.14 to 26.167.137.15—2
13726.167.137.16/3126.167.137.16 to 26.167.137.17—2
13826.167.137.18/3126.167.137.18 to 26.167.137.19—2
13926.167.137.20/3126.167.137.20 to 26.167.137.21—2
14026.167.137.22/3126.167.137.22 to 26.167.137.23—2
14126.167.137.24/3126.167.137.24 to 26.167.137.25—2
14226.167.137.26/3126.167.137.26 to 26.167.137.27—2
14326.167.137.28/3126.167.137.28 to 26.167.137.29—2
14426.167.137.30/3126.167.137.30 to 26.167.137.31—2
14526.167.137.32/3126.167.137.32 to 26.167.137.33—2
14626.167.137.34/3126.167.137.34 to 26.167.137.35—2
14726.167.137.36/3126.167.137.36 to 26.167.137.37—2
14826.167.137.38/3126.167.137.38 to 26.167.137.39—2
14926.167.137.40/3126.167.137.40 to 26.167.137.41—2
15026.167.137.42/3126.167.137.42 to 26.167.137.43—2
15126.167.137.44/3126.167.137.44 to 26.167.137.45—2
15226.167.137.46/3126.167.137.46 to 26.167.137.47—2
15326.167.137.48/3126.167.137.48 to 26.167.137.49—2
15426.167.137.50/3126.167.137.50 to 26.167.137.51—2
15526.167.137.52/3126.167.137.52 to 26.167.137.53—2
15626.167.137.54/3126.167.137.54 to 26.167.137.55—2
15726.167.137.56/3126.167.137.56 to 26.167.137.57—2
15826.167.137.58/3126.167.137.58 to 26.167.137.59—2
15926.167.137.60/3126.167.137.60 to 26.167.137.61—2
16026.167.137.62/3126.167.137.62 to 26.167.137.63—2
16126.167.137.64/3126.167.137.64 to 26.167.137.65—2
16226.167.137.66/3126.167.137.66 to 26.167.137.67—2
16326.167.137.68/3126.167.137.68 to 26.167.137.69—2
16426.167.137.70/3126.167.137.70 to 26.167.137.71—2
16526.167.137.72/3126.167.137.72 to 26.167.137.73—2
16626.167.137.74/3126.167.137.74 to 26.167.137.75—2
16726.167.137.76/3126.167.137.76 to 26.167.137.77—2
16826.167.137.78/3126.167.137.78 to 26.167.137.79—2
16926.167.137.80/3126.167.137.80 to 26.167.137.81—2
17026.167.137.82/3126.167.137.82 to 26.167.137.83—2
17126.167.137.84/3126.167.137.84 to 26.167.137.85—2
17226.167.137.86/3126.167.137.86 to 26.167.137.87—2
17326.167.137.88/3126.167.137.88 to 26.167.137.89—2
17426.167.137.90/3126.167.137.90 to 26.167.137.91—2
17526.167.137.92/3126.167.137.92 to 26.167.137.93—2
17626.167.137.94/3126.167.137.94 to 26.167.137.95—2
17726.167.137.96/3126.167.137.96 to 26.167.137.97—2
17826.167.137.98/3126.167.137.98 to 26.167.137.99—2
17926.167.137.100/3126.167.137.100 to 26.167.137.101—2
18026.167.137.102/3126.167.137.102 to 26.167.137.103—2
18126.167.137.104/3126.167.137.104 to 26.167.137.105—2
18226.167.137.106/3126.167.137.106 to 26.167.137.107—2
18326.167.137.108/3126.167.137.108 to 26.167.137.109—2
18426.167.137.110/3126.167.137.110 to 26.167.137.111—2
18526.167.137.112/3126.167.137.112 to 26.167.137.113—2
18626.167.137.114/3126.167.137.114 to 26.167.137.115—2
18726.167.137.116/3126.167.137.116 to 26.167.137.117—2
18826.167.137.118/3126.167.137.118 to 26.167.137.119—2
18926.167.137.120/3126.167.137.120 to 26.167.137.121—2
19026.167.137.122/3126.167.137.122 to 26.167.137.123—2
19126.167.137.124/3126.167.137.124 to 26.167.137.125—2
19226.167.137.126/3126.167.137.126 to 26.167.137.127—2
19326.167.137.128/3126.167.137.128 to 26.167.137.129—2
19426.167.137.130/3126.167.137.130 to 26.167.137.131—2
19526.167.137.132/3126.167.137.132 to 26.167.137.133—2
19626.167.137.134/3126.167.137.134 to 26.167.137.135—2
19726.167.137.136/3126.167.137.136 to 26.167.137.137—2
19826.167.137.138/3126.167.137.138 to 26.167.137.139—2
19926.167.137.140/3126.167.137.140 to 26.167.137.141—2
20026.167.137.142/3126.167.137.142 to 26.167.137.143—2
20126.167.137.144/3126.167.137.144 to 26.167.137.145—2
20226.167.137.146/3126.167.137.146 to 26.167.137.147—2
20326.167.137.148/3126.167.137.148 to 26.167.137.149—2
20426.167.137.150/3126.167.137.150 to 26.167.137.151—2
20526.167.137.152/3126.167.137.152 to 26.167.137.153—2
20626.167.137.154/3126.167.137.154 to 26.167.137.155—2
20726.167.137.156/3126.167.137.156 to 26.167.137.157—2
20826.167.137.158/3126.167.137.158 to 26.167.137.159—2
20926.167.137.160/3126.167.137.160 to 26.167.137.161—2
21026.167.137.162/3126.167.137.162 to 26.167.137.163—2
21126.167.137.164/3126.167.137.164 to 26.167.137.165—2
21226.167.137.166/3126.167.137.166 to 26.167.137.167—2
21326.167.137.168/3126.167.137.168 to 26.167.137.169—2
21426.167.137.170/3126.167.137.170 to 26.167.137.171—2
21526.167.137.172/3126.167.137.172 to 26.167.137.173—2
21626.167.137.174/3126.167.137.174 to 26.167.137.175—2
21726.167.137.176/3126.167.137.176 to 26.167.137.177—2
21826.167.137.178/3126.167.137.178 to 26.167.137.179—2
21926.167.137.180/3126.167.137.180 to 26.167.137.181—2
22026.167.137.182/3126.167.137.182 to 26.167.137.183—2
22126.167.137.184/3126.167.137.184 to 26.167.137.185—2
22226.167.137.186/3126.167.137.186 to 26.167.137.187—2
22326.167.137.188/3126.167.137.188 to 26.167.137.189—2
22426.167.137.190/3126.167.137.190 to 26.167.137.191—2
22526.167.137.192/3126.167.137.192 to 26.167.137.193—2
22626.167.137.194/3126.167.137.194 to 26.167.137.195—2
22726.167.137.196/3126.167.137.196 to 26.167.137.197—2
22826.167.137.198/3126.167.137.198 to 26.167.137.199—2
22926.167.137.200/3126.167.137.200 to 26.167.137.201—2
23026.167.137.202/3126.167.137.202 to 26.167.137.203—2
23126.167.137.204/3126.167.137.204 to 26.167.137.205—2
23226.167.137.206/3126.167.137.206 to 26.167.137.207—2
23326.167.137.208/3126.167.137.208 to 26.167.137.209—2
23426.167.137.210/3126.167.137.210 to 26.167.137.211—2
23526.167.137.212/3126.167.137.212 to 26.167.137.213—2
23626.167.137.214/3126.167.137.214 to 26.167.137.215—2
23726.167.137.216/3126.167.137.216 to 26.167.137.217—2
23826.167.137.218/3126.167.137.218 to 26.167.137.219—2
23926.167.137.220/3126.167.137.220 to 26.167.137.221—2
24026.167.137.222/3126.167.137.222 to 26.167.137.223—2
24126.167.137.224/3126.167.137.224 to 26.167.137.225—2
24226.167.137.226/3126.167.137.226 to 26.167.137.227—2
24326.167.137.228/3126.167.137.228 to 26.167.137.229—2
24426.167.137.230/3126.167.137.230 to 26.167.137.231—2
24526.167.137.232/3126.167.137.232 to 26.167.137.233—2
24626.167.137.234/3126.167.137.234 to 26.167.137.235—2
24726.167.137.236/3126.167.137.236 to 26.167.137.237—2
24826.167.137.238/3126.167.137.238 to 26.167.137.239—2
24926.167.137.240/3126.167.137.240 to 26.167.137.241—2
25026.167.137.242/3126.167.137.242 to 26.167.137.243—2
25126.167.137.244/3126.167.137.244 to 26.167.137.245—2
25226.167.137.246/3126.167.137.246 to 26.167.137.247—2
25326.167.137.248/3126.167.137.248 to 26.167.137.249—2
25426.167.137.250/3126.167.137.250 to 26.167.137.251—2
25526.167.137.252/3126.167.137.252 to 26.167.137.253—2
25626.167.137.254/3126.167.137.254 to 26.167.137.255—2

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.