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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.

Network27.237.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
27.237.0.0
Broadcast address
27.237.31.255
First usable
27.237.0.1
Last usable
27.237.31.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 1BED0000 · Integer 468516864 to 468525055
Reverse DNS zones
0.237.27.in-addr.arpa
1.237.27.in-addr.arpa
2.237.27.in-addr.arpa
3.237.27.in-addr.arpa
4.237.27.in-addr.arpa
5.237.27.in-addr.arpa
6.237.27.in-addr.arpa
7.237.27.in-addr.arpa
8.237.27.in-addr.arpa
9.237.27.in-addr.arpa
10.237.27.in-addr.arpa
11.237.27.in-addr.arpa
12.237.27.in-addr.arpa
13.237.27.in-addr.arpa
14.237.27.in-addr.arpa
15.237.27.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011011.11101101.00000000.0000000027.237.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network00011011.11101101.00000000.0000000027.237.0.0
Broadcast00011011.11101101.00011111.1111111127.237.31.255
Split into smaller subnets/31
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

27.237.0.0/19 makes 4,096 subnets of /31; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
127.237.0.0/3127.237.0.0 to 27.237.0.1—2
227.237.0.2/3127.237.0.2 to 27.237.0.3—2
327.237.0.4/3127.237.0.4 to 27.237.0.5—2
427.237.0.6/3127.237.0.6 to 27.237.0.7—2
527.237.0.8/3127.237.0.8 to 27.237.0.9—2
627.237.0.10/3127.237.0.10 to 27.237.0.11—2
727.237.0.12/3127.237.0.12 to 27.237.0.13—2
827.237.0.14/3127.237.0.14 to 27.237.0.15—2
927.237.0.16/3127.237.0.16 to 27.237.0.17—2
1027.237.0.18/3127.237.0.18 to 27.237.0.19—2
1127.237.0.20/3127.237.0.20 to 27.237.0.21—2
1227.237.0.22/3127.237.0.22 to 27.237.0.23—2
1327.237.0.24/3127.237.0.24 to 27.237.0.25—2
1427.237.0.26/3127.237.0.26 to 27.237.0.27—2
1527.237.0.28/3127.237.0.28 to 27.237.0.29—2
1627.237.0.30/3127.237.0.30 to 27.237.0.31—2
1727.237.0.32/3127.237.0.32 to 27.237.0.33—2
1827.237.0.34/3127.237.0.34 to 27.237.0.35—2
1927.237.0.36/3127.237.0.36 to 27.237.0.37—2
2027.237.0.38/3127.237.0.38 to 27.237.0.39—2
2127.237.0.40/3127.237.0.40 to 27.237.0.41—2
2227.237.0.42/3127.237.0.42 to 27.237.0.43—2
2327.237.0.44/3127.237.0.44 to 27.237.0.45—2
2427.237.0.46/3127.237.0.46 to 27.237.0.47—2
2527.237.0.48/3127.237.0.48 to 27.237.0.49—2
2627.237.0.50/3127.237.0.50 to 27.237.0.51—2
2727.237.0.52/3127.237.0.52 to 27.237.0.53—2
2827.237.0.54/3127.237.0.54 to 27.237.0.55—2
2927.237.0.56/3127.237.0.56 to 27.237.0.57—2
3027.237.0.58/3127.237.0.58 to 27.237.0.59—2
3127.237.0.60/3127.237.0.60 to 27.237.0.61—2
3227.237.0.62/3127.237.0.62 to 27.237.0.63—2
3327.237.0.64/3127.237.0.64 to 27.237.0.65—2
3427.237.0.66/3127.237.0.66 to 27.237.0.67—2
3527.237.0.68/3127.237.0.68 to 27.237.0.69—2
3627.237.0.70/3127.237.0.70 to 27.237.0.71—2
3727.237.0.72/3127.237.0.72 to 27.237.0.73—2
3827.237.0.74/3127.237.0.74 to 27.237.0.75—2
3927.237.0.76/3127.237.0.76 to 27.237.0.77—2
4027.237.0.78/3127.237.0.78 to 27.237.0.79—2
4127.237.0.80/3127.237.0.80 to 27.237.0.81—2
4227.237.0.82/3127.237.0.82 to 27.237.0.83—2
4327.237.0.84/3127.237.0.84 to 27.237.0.85—2
4427.237.0.86/3127.237.0.86 to 27.237.0.87—2
4527.237.0.88/3127.237.0.88 to 27.237.0.89—2
4627.237.0.90/3127.237.0.90 to 27.237.0.91—2
4727.237.0.92/3127.237.0.92 to 27.237.0.93—2
4827.237.0.94/3127.237.0.94 to 27.237.0.95—2
4927.237.0.96/3127.237.0.96 to 27.237.0.97—2
5027.237.0.98/3127.237.0.98 to 27.237.0.99—2
5127.237.0.100/3127.237.0.100 to 27.237.0.101—2
5227.237.0.102/3127.237.0.102 to 27.237.0.103—2
5327.237.0.104/3127.237.0.104 to 27.237.0.105—2
5427.237.0.106/3127.237.0.106 to 27.237.0.107—2
5527.237.0.108/3127.237.0.108 to 27.237.0.109—2
5627.237.0.110/3127.237.0.110 to 27.237.0.111—2
5727.237.0.112/3127.237.0.112 to 27.237.0.113—2
5827.237.0.114/3127.237.0.114 to 27.237.0.115—2
5927.237.0.116/3127.237.0.116 to 27.237.0.117—2
6027.237.0.118/3127.237.0.118 to 27.237.0.119—2
6127.237.0.120/3127.237.0.120 to 27.237.0.121—2
6227.237.0.122/3127.237.0.122 to 27.237.0.123—2
6327.237.0.124/3127.237.0.124 to 27.237.0.125—2
6427.237.0.126/3127.237.0.126 to 27.237.0.127—2
6527.237.0.128/3127.237.0.128 to 27.237.0.129—2
6627.237.0.130/3127.237.0.130 to 27.237.0.131—2
6727.237.0.132/3127.237.0.132 to 27.237.0.133—2
6827.237.0.134/3127.237.0.134 to 27.237.0.135—2
6927.237.0.136/3127.237.0.136 to 27.237.0.137—2
7027.237.0.138/3127.237.0.138 to 27.237.0.139—2
7127.237.0.140/3127.237.0.140 to 27.237.0.141—2
7227.237.0.142/3127.237.0.142 to 27.237.0.143—2
7327.237.0.144/3127.237.0.144 to 27.237.0.145—2
7427.237.0.146/3127.237.0.146 to 27.237.0.147—2
7527.237.0.148/3127.237.0.148 to 27.237.0.149—2
7627.237.0.150/3127.237.0.150 to 27.237.0.151—2
7727.237.0.152/3127.237.0.152 to 27.237.0.153—2
7827.237.0.154/3127.237.0.154 to 27.237.0.155—2
7927.237.0.156/3127.237.0.156 to 27.237.0.157—2
8027.237.0.158/3127.237.0.158 to 27.237.0.159—2
8127.237.0.160/3127.237.0.160 to 27.237.0.161—2
8227.237.0.162/3127.237.0.162 to 27.237.0.163—2
8327.237.0.164/3127.237.0.164 to 27.237.0.165—2
8427.237.0.166/3127.237.0.166 to 27.237.0.167—2
8527.237.0.168/3127.237.0.168 to 27.237.0.169—2
8627.237.0.170/3127.237.0.170 to 27.237.0.171—2
8727.237.0.172/3127.237.0.172 to 27.237.0.173—2
8827.237.0.174/3127.237.0.174 to 27.237.0.175—2
8927.237.0.176/3127.237.0.176 to 27.237.0.177—2
9027.237.0.178/3127.237.0.178 to 27.237.0.179—2
9127.237.0.180/3127.237.0.180 to 27.237.0.181—2
9227.237.0.182/3127.237.0.182 to 27.237.0.183—2
9327.237.0.184/3127.237.0.184 to 27.237.0.185—2
9427.237.0.186/3127.237.0.186 to 27.237.0.187—2
9527.237.0.188/3127.237.0.188 to 27.237.0.189—2
9627.237.0.190/3127.237.0.190 to 27.237.0.191—2
9727.237.0.192/3127.237.0.192 to 27.237.0.193—2
9827.237.0.194/3127.237.0.194 to 27.237.0.195—2
9927.237.0.196/3127.237.0.196 to 27.237.0.197—2
10027.237.0.198/3127.237.0.198 to 27.237.0.199—2
10127.237.0.200/3127.237.0.200 to 27.237.0.201—2
10227.237.0.202/3127.237.0.202 to 27.237.0.203—2
10327.237.0.204/3127.237.0.204 to 27.237.0.205—2
10427.237.0.206/3127.237.0.206 to 27.237.0.207—2
10527.237.0.208/3127.237.0.208 to 27.237.0.209—2
10627.237.0.210/3127.237.0.210 to 27.237.0.211—2
10727.237.0.212/3127.237.0.212 to 27.237.0.213—2
10827.237.0.214/3127.237.0.214 to 27.237.0.215—2
10927.237.0.216/3127.237.0.216 to 27.237.0.217—2
11027.237.0.218/3127.237.0.218 to 27.237.0.219—2
11127.237.0.220/3127.237.0.220 to 27.237.0.221—2
11227.237.0.222/3127.237.0.222 to 27.237.0.223—2
11327.237.0.224/3127.237.0.224 to 27.237.0.225—2
11427.237.0.226/3127.237.0.226 to 27.237.0.227—2
11527.237.0.228/3127.237.0.228 to 27.237.0.229—2
11627.237.0.230/3127.237.0.230 to 27.237.0.231—2
11727.237.0.232/3127.237.0.232 to 27.237.0.233—2
11827.237.0.234/3127.237.0.234 to 27.237.0.235—2
11927.237.0.236/3127.237.0.236 to 27.237.0.237—2
12027.237.0.238/3127.237.0.238 to 27.237.0.239—2
12127.237.0.240/3127.237.0.240 to 27.237.0.241—2
12227.237.0.242/3127.237.0.242 to 27.237.0.243—2
12327.237.0.244/3127.237.0.244 to 27.237.0.245—2
12427.237.0.246/3127.237.0.246 to 27.237.0.247—2
12527.237.0.248/3127.237.0.248 to 27.237.0.249—2
12627.237.0.250/3127.237.0.250 to 27.237.0.251—2
12727.237.0.252/3127.237.0.252 to 27.237.0.253—2
12827.237.0.254/3127.237.0.254 to 27.237.0.255—2
12927.237.1.0/3127.237.1.0 to 27.237.1.1—2
13027.237.1.2/3127.237.1.2 to 27.237.1.3—2
13127.237.1.4/3127.237.1.4 to 27.237.1.5—2
13227.237.1.6/3127.237.1.6 to 27.237.1.7—2
13327.237.1.8/3127.237.1.8 to 27.237.1.9—2
13427.237.1.10/3127.237.1.10 to 27.237.1.11—2
13527.237.1.12/3127.237.1.12 to 27.237.1.13—2
13627.237.1.14/3127.237.1.14 to 27.237.1.15—2
13727.237.1.16/3127.237.1.16 to 27.237.1.17—2
13827.237.1.18/3127.237.1.18 to 27.237.1.19—2
13927.237.1.20/3127.237.1.20 to 27.237.1.21—2
14027.237.1.22/3127.237.1.22 to 27.237.1.23—2
14127.237.1.24/3127.237.1.24 to 27.237.1.25—2
14227.237.1.26/3127.237.1.26 to 27.237.1.27—2
14327.237.1.28/3127.237.1.28 to 27.237.1.29—2
14427.237.1.30/3127.237.1.30 to 27.237.1.31—2
14527.237.1.32/3127.237.1.32 to 27.237.1.33—2
14627.237.1.34/3127.237.1.34 to 27.237.1.35—2
14727.237.1.36/3127.237.1.36 to 27.237.1.37—2
14827.237.1.38/3127.237.1.38 to 27.237.1.39—2
14927.237.1.40/3127.237.1.40 to 27.237.1.41—2
15027.237.1.42/3127.237.1.42 to 27.237.1.43—2
15127.237.1.44/3127.237.1.44 to 27.237.1.45—2
15227.237.1.46/3127.237.1.46 to 27.237.1.47—2
15327.237.1.48/3127.237.1.48 to 27.237.1.49—2
15427.237.1.50/3127.237.1.50 to 27.237.1.51—2
15527.237.1.52/3127.237.1.52 to 27.237.1.53—2
15627.237.1.54/3127.237.1.54 to 27.237.1.55—2
15727.237.1.56/3127.237.1.56 to 27.237.1.57—2
15827.237.1.58/3127.237.1.58 to 27.237.1.59—2
15927.237.1.60/3127.237.1.60 to 27.237.1.61—2
16027.237.1.62/3127.237.1.62 to 27.237.1.63—2
16127.237.1.64/3127.237.1.64 to 27.237.1.65—2
16227.237.1.66/3127.237.1.66 to 27.237.1.67—2
16327.237.1.68/3127.237.1.68 to 27.237.1.69—2
16427.237.1.70/3127.237.1.70 to 27.237.1.71—2
16527.237.1.72/3127.237.1.72 to 27.237.1.73—2
16627.237.1.74/3127.237.1.74 to 27.237.1.75—2
16727.237.1.76/3127.237.1.76 to 27.237.1.77—2
16827.237.1.78/3127.237.1.78 to 27.237.1.79—2
16927.237.1.80/3127.237.1.80 to 27.237.1.81—2
17027.237.1.82/3127.237.1.82 to 27.237.1.83—2
17127.237.1.84/3127.237.1.84 to 27.237.1.85—2
17227.237.1.86/3127.237.1.86 to 27.237.1.87—2
17327.237.1.88/3127.237.1.88 to 27.237.1.89—2
17427.237.1.90/3127.237.1.90 to 27.237.1.91—2
17527.237.1.92/3127.237.1.92 to 27.237.1.93—2
17627.237.1.94/3127.237.1.94 to 27.237.1.95—2
17727.237.1.96/3127.237.1.96 to 27.237.1.97—2
17827.237.1.98/3127.237.1.98 to 27.237.1.99—2
17927.237.1.100/3127.237.1.100 to 27.237.1.101—2
18027.237.1.102/3127.237.1.102 to 27.237.1.103—2
18127.237.1.104/3127.237.1.104 to 27.237.1.105—2
18227.237.1.106/3127.237.1.106 to 27.237.1.107—2
18327.237.1.108/3127.237.1.108 to 27.237.1.109—2
18427.237.1.110/3127.237.1.110 to 27.237.1.111—2
18527.237.1.112/3127.237.1.112 to 27.237.1.113—2
18627.237.1.114/3127.237.1.114 to 27.237.1.115—2
18727.237.1.116/3127.237.1.116 to 27.237.1.117—2
18827.237.1.118/3127.237.1.118 to 27.237.1.119—2
18927.237.1.120/3127.237.1.120 to 27.237.1.121—2
19027.237.1.122/3127.237.1.122 to 27.237.1.123—2
19127.237.1.124/3127.237.1.124 to 27.237.1.125—2
19227.237.1.126/3127.237.1.126 to 27.237.1.127—2
19327.237.1.128/3127.237.1.128 to 27.237.1.129—2
19427.237.1.130/3127.237.1.130 to 27.237.1.131—2
19527.237.1.132/3127.237.1.132 to 27.237.1.133—2
19627.237.1.134/3127.237.1.134 to 27.237.1.135—2
19727.237.1.136/3127.237.1.136 to 27.237.1.137—2
19827.237.1.138/3127.237.1.138 to 27.237.1.139—2
19927.237.1.140/3127.237.1.140 to 27.237.1.141—2
20027.237.1.142/3127.237.1.142 to 27.237.1.143—2
20127.237.1.144/3127.237.1.144 to 27.237.1.145—2
20227.237.1.146/3127.237.1.146 to 27.237.1.147—2
20327.237.1.148/3127.237.1.148 to 27.237.1.149—2
20427.237.1.150/3127.237.1.150 to 27.237.1.151—2
20527.237.1.152/3127.237.1.152 to 27.237.1.153—2
20627.237.1.154/3127.237.1.154 to 27.237.1.155—2
20727.237.1.156/3127.237.1.156 to 27.237.1.157—2
20827.237.1.158/3127.237.1.158 to 27.237.1.159—2
20927.237.1.160/3127.237.1.160 to 27.237.1.161—2
21027.237.1.162/3127.237.1.162 to 27.237.1.163—2
21127.237.1.164/3127.237.1.164 to 27.237.1.165—2
21227.237.1.166/3127.237.1.166 to 27.237.1.167—2
21327.237.1.168/3127.237.1.168 to 27.237.1.169—2
21427.237.1.170/3127.237.1.170 to 27.237.1.171—2
21527.237.1.172/3127.237.1.172 to 27.237.1.173—2
21627.237.1.174/3127.237.1.174 to 27.237.1.175—2
21727.237.1.176/3127.237.1.176 to 27.237.1.177—2
21827.237.1.178/3127.237.1.178 to 27.237.1.179—2
21927.237.1.180/3127.237.1.180 to 27.237.1.181—2
22027.237.1.182/3127.237.1.182 to 27.237.1.183—2
22127.237.1.184/3127.237.1.184 to 27.237.1.185—2
22227.237.1.186/3127.237.1.186 to 27.237.1.187—2
22327.237.1.188/3127.237.1.188 to 27.237.1.189—2
22427.237.1.190/3127.237.1.190 to 27.237.1.191—2
22527.237.1.192/3127.237.1.192 to 27.237.1.193—2
22627.237.1.194/3127.237.1.194 to 27.237.1.195—2
22727.237.1.196/3127.237.1.196 to 27.237.1.197—2
22827.237.1.198/3127.237.1.198 to 27.237.1.199—2
22927.237.1.200/3127.237.1.200 to 27.237.1.201—2
23027.237.1.202/3127.237.1.202 to 27.237.1.203—2
23127.237.1.204/3127.237.1.204 to 27.237.1.205—2
23227.237.1.206/3127.237.1.206 to 27.237.1.207—2
23327.237.1.208/3127.237.1.208 to 27.237.1.209—2
23427.237.1.210/3127.237.1.210 to 27.237.1.211—2
23527.237.1.212/3127.237.1.212 to 27.237.1.213—2
23627.237.1.214/3127.237.1.214 to 27.237.1.215—2
23727.237.1.216/3127.237.1.216 to 27.237.1.217—2
23827.237.1.218/3127.237.1.218 to 27.237.1.219—2
23927.237.1.220/3127.237.1.220 to 27.237.1.221—2
24027.237.1.222/3127.237.1.222 to 27.237.1.223—2
24127.237.1.224/3127.237.1.224 to 27.237.1.225—2
24227.237.1.226/3127.237.1.226 to 27.237.1.227—2
24327.237.1.228/3127.237.1.228 to 27.237.1.229—2
24427.237.1.230/3127.237.1.230 to 27.237.1.231—2
24527.237.1.232/3127.237.1.232 to 27.237.1.233—2
24627.237.1.234/3127.237.1.234 to 27.237.1.235—2
24727.237.1.236/3127.237.1.236 to 27.237.1.237—2
24827.237.1.238/3127.237.1.238 to 27.237.1.239—2
24927.237.1.240/3127.237.1.240 to 27.237.1.241—2
25027.237.1.242/3127.237.1.242 to 27.237.1.243—2
25127.237.1.244/3127.237.1.244 to 27.237.1.245—2
25227.237.1.246/3127.237.1.246 to 27.237.1.247—2
25327.237.1.248/3127.237.1.248 to 27.237.1.249—2
25427.237.1.250/3127.237.1.250 to 27.237.1.251—2
25527.237.1.252/3127.237.1.252 to 27.237.1.253—2
25627.237.1.254/3127.237.1.254 to 27.237.1.255—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.