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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.

Network83.4.64.0/21
Usable hosts2,046
Subnet mask255.255.248.0
Addresses2,048
Network address
83.4.64.0
Broadcast address
83.4.71.255
First usable
83.4.64.1
Last usable
83.4.71.254
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 53044000 · Integer 1392787456 to 1392789503
Reverse DNS zones
64.4.83.in-addr.arpa
65.4.83.in-addr.arpa
66.4.83.in-addr.arpa
67.4.83.in-addr.arpa
68.4.83.in-addr.arpa
69.4.83.in-addr.arpa
70.4.83.in-addr.arpa
71.4.83.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
Address01010011.00000100.01000000.0000000083.4.64.0
Subnet mask11111111.11111111.11111000.00000000255.255.248.0
Network01010011.00000100.01000000.0000000083.4.64.0
Broadcast01010011.00000100.01000111.1111111183.4.71.255
Split into smaller subnets/30
/22 (2)/23 (4)/24 (8)/25 (16)/26 (32)/27 (64)/28 (128)/29 (256)/30 (512)/31 (1,024)/32 (2,048)

83.4.64.0/21 makes 512 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
183.4.64.0/3083.4.64.1 to 83.4.64.283.4.64.32
283.4.64.4/3083.4.64.5 to 83.4.64.683.4.64.72
383.4.64.8/3083.4.64.9 to 83.4.64.1083.4.64.112
483.4.64.12/3083.4.64.13 to 83.4.64.1483.4.64.152
583.4.64.16/3083.4.64.17 to 83.4.64.1883.4.64.192
683.4.64.20/3083.4.64.21 to 83.4.64.2283.4.64.232
783.4.64.24/3083.4.64.25 to 83.4.64.2683.4.64.272
883.4.64.28/3083.4.64.29 to 83.4.64.3083.4.64.312
983.4.64.32/3083.4.64.33 to 83.4.64.3483.4.64.352
1083.4.64.36/3083.4.64.37 to 83.4.64.3883.4.64.392
1183.4.64.40/3083.4.64.41 to 83.4.64.4283.4.64.432
1283.4.64.44/3083.4.64.45 to 83.4.64.4683.4.64.472
1383.4.64.48/3083.4.64.49 to 83.4.64.5083.4.64.512
1483.4.64.52/3083.4.64.53 to 83.4.64.5483.4.64.552
1583.4.64.56/3083.4.64.57 to 83.4.64.5883.4.64.592
1683.4.64.60/3083.4.64.61 to 83.4.64.6283.4.64.632
1783.4.64.64/3083.4.64.65 to 83.4.64.6683.4.64.672
1883.4.64.68/3083.4.64.69 to 83.4.64.7083.4.64.712
1983.4.64.72/3083.4.64.73 to 83.4.64.7483.4.64.752
2083.4.64.76/3083.4.64.77 to 83.4.64.7883.4.64.792
2183.4.64.80/3083.4.64.81 to 83.4.64.8283.4.64.832
2283.4.64.84/3083.4.64.85 to 83.4.64.8683.4.64.872
2383.4.64.88/3083.4.64.89 to 83.4.64.9083.4.64.912
2483.4.64.92/3083.4.64.93 to 83.4.64.9483.4.64.952
2583.4.64.96/3083.4.64.97 to 83.4.64.9883.4.64.992
2683.4.64.100/3083.4.64.101 to 83.4.64.10283.4.64.1032
2783.4.64.104/3083.4.64.105 to 83.4.64.10683.4.64.1072
2883.4.64.108/3083.4.64.109 to 83.4.64.11083.4.64.1112
2983.4.64.112/3083.4.64.113 to 83.4.64.11483.4.64.1152
3083.4.64.116/3083.4.64.117 to 83.4.64.11883.4.64.1192
3183.4.64.120/3083.4.64.121 to 83.4.64.12283.4.64.1232
3283.4.64.124/3083.4.64.125 to 83.4.64.12683.4.64.1272
3383.4.64.128/3083.4.64.129 to 83.4.64.13083.4.64.1312
3483.4.64.132/3083.4.64.133 to 83.4.64.13483.4.64.1352
3583.4.64.136/3083.4.64.137 to 83.4.64.13883.4.64.1392
3683.4.64.140/3083.4.64.141 to 83.4.64.14283.4.64.1432
3783.4.64.144/3083.4.64.145 to 83.4.64.14683.4.64.1472
3883.4.64.148/3083.4.64.149 to 83.4.64.15083.4.64.1512
3983.4.64.152/3083.4.64.153 to 83.4.64.15483.4.64.1552
4083.4.64.156/3083.4.64.157 to 83.4.64.15883.4.64.1592
4183.4.64.160/3083.4.64.161 to 83.4.64.16283.4.64.1632
4283.4.64.164/3083.4.64.165 to 83.4.64.16683.4.64.1672
4383.4.64.168/3083.4.64.169 to 83.4.64.17083.4.64.1712
4483.4.64.172/3083.4.64.173 to 83.4.64.17483.4.64.1752
4583.4.64.176/3083.4.64.177 to 83.4.64.17883.4.64.1792
4683.4.64.180/3083.4.64.181 to 83.4.64.18283.4.64.1832
4783.4.64.184/3083.4.64.185 to 83.4.64.18683.4.64.1872
4883.4.64.188/3083.4.64.189 to 83.4.64.19083.4.64.1912
4983.4.64.192/3083.4.64.193 to 83.4.64.19483.4.64.1952
5083.4.64.196/3083.4.64.197 to 83.4.64.19883.4.64.1992
5183.4.64.200/3083.4.64.201 to 83.4.64.20283.4.64.2032
5283.4.64.204/3083.4.64.205 to 83.4.64.20683.4.64.2072
5383.4.64.208/3083.4.64.209 to 83.4.64.21083.4.64.2112
5483.4.64.212/3083.4.64.213 to 83.4.64.21483.4.64.2152
5583.4.64.216/3083.4.64.217 to 83.4.64.21883.4.64.2192
5683.4.64.220/3083.4.64.221 to 83.4.64.22283.4.64.2232
5783.4.64.224/3083.4.64.225 to 83.4.64.22683.4.64.2272
5883.4.64.228/3083.4.64.229 to 83.4.64.23083.4.64.2312
5983.4.64.232/3083.4.64.233 to 83.4.64.23483.4.64.2352
6083.4.64.236/3083.4.64.237 to 83.4.64.23883.4.64.2392
6183.4.64.240/3083.4.64.241 to 83.4.64.24283.4.64.2432
6283.4.64.244/3083.4.64.245 to 83.4.64.24683.4.64.2472
6383.4.64.248/3083.4.64.249 to 83.4.64.25083.4.64.2512
6483.4.64.252/3083.4.64.253 to 83.4.64.25483.4.64.2552
6583.4.65.0/3083.4.65.1 to 83.4.65.283.4.65.32
6683.4.65.4/3083.4.65.5 to 83.4.65.683.4.65.72
6783.4.65.8/3083.4.65.9 to 83.4.65.1083.4.65.112
6883.4.65.12/3083.4.65.13 to 83.4.65.1483.4.65.152
6983.4.65.16/3083.4.65.17 to 83.4.65.1883.4.65.192
7083.4.65.20/3083.4.65.21 to 83.4.65.2283.4.65.232
7183.4.65.24/3083.4.65.25 to 83.4.65.2683.4.65.272
7283.4.65.28/3083.4.65.29 to 83.4.65.3083.4.65.312
7383.4.65.32/3083.4.65.33 to 83.4.65.3483.4.65.352
7483.4.65.36/3083.4.65.37 to 83.4.65.3883.4.65.392
7583.4.65.40/3083.4.65.41 to 83.4.65.4283.4.65.432
7683.4.65.44/3083.4.65.45 to 83.4.65.4683.4.65.472
7783.4.65.48/3083.4.65.49 to 83.4.65.5083.4.65.512
7883.4.65.52/3083.4.65.53 to 83.4.65.5483.4.65.552
7983.4.65.56/3083.4.65.57 to 83.4.65.5883.4.65.592
8083.4.65.60/3083.4.65.61 to 83.4.65.6283.4.65.632
8183.4.65.64/3083.4.65.65 to 83.4.65.6683.4.65.672
8283.4.65.68/3083.4.65.69 to 83.4.65.7083.4.65.712
8383.4.65.72/3083.4.65.73 to 83.4.65.7483.4.65.752
8483.4.65.76/3083.4.65.77 to 83.4.65.7883.4.65.792
8583.4.65.80/3083.4.65.81 to 83.4.65.8283.4.65.832
8683.4.65.84/3083.4.65.85 to 83.4.65.8683.4.65.872
8783.4.65.88/3083.4.65.89 to 83.4.65.9083.4.65.912
8883.4.65.92/3083.4.65.93 to 83.4.65.9483.4.65.952
8983.4.65.96/3083.4.65.97 to 83.4.65.9883.4.65.992
9083.4.65.100/3083.4.65.101 to 83.4.65.10283.4.65.1032
9183.4.65.104/3083.4.65.105 to 83.4.65.10683.4.65.1072
9283.4.65.108/3083.4.65.109 to 83.4.65.11083.4.65.1112
9383.4.65.112/3083.4.65.113 to 83.4.65.11483.4.65.1152
9483.4.65.116/3083.4.65.117 to 83.4.65.11883.4.65.1192
9583.4.65.120/3083.4.65.121 to 83.4.65.12283.4.65.1232
9683.4.65.124/3083.4.65.125 to 83.4.65.12683.4.65.1272
9783.4.65.128/3083.4.65.129 to 83.4.65.13083.4.65.1312
9883.4.65.132/3083.4.65.133 to 83.4.65.13483.4.65.1352
9983.4.65.136/3083.4.65.137 to 83.4.65.13883.4.65.1392
10083.4.65.140/3083.4.65.141 to 83.4.65.14283.4.65.1432
10183.4.65.144/3083.4.65.145 to 83.4.65.14683.4.65.1472
10283.4.65.148/3083.4.65.149 to 83.4.65.15083.4.65.1512
10383.4.65.152/3083.4.65.153 to 83.4.65.15483.4.65.1552
10483.4.65.156/3083.4.65.157 to 83.4.65.15883.4.65.1592
10583.4.65.160/3083.4.65.161 to 83.4.65.16283.4.65.1632
10683.4.65.164/3083.4.65.165 to 83.4.65.16683.4.65.1672
10783.4.65.168/3083.4.65.169 to 83.4.65.17083.4.65.1712
10883.4.65.172/3083.4.65.173 to 83.4.65.17483.4.65.1752
10983.4.65.176/3083.4.65.177 to 83.4.65.17883.4.65.1792
11083.4.65.180/3083.4.65.181 to 83.4.65.18283.4.65.1832
11183.4.65.184/3083.4.65.185 to 83.4.65.18683.4.65.1872
11283.4.65.188/3083.4.65.189 to 83.4.65.19083.4.65.1912
11383.4.65.192/3083.4.65.193 to 83.4.65.19483.4.65.1952
11483.4.65.196/3083.4.65.197 to 83.4.65.19883.4.65.1992
11583.4.65.200/3083.4.65.201 to 83.4.65.20283.4.65.2032
11683.4.65.204/3083.4.65.205 to 83.4.65.20683.4.65.2072
11783.4.65.208/3083.4.65.209 to 83.4.65.21083.4.65.2112
11883.4.65.212/3083.4.65.213 to 83.4.65.21483.4.65.2152
11983.4.65.216/3083.4.65.217 to 83.4.65.21883.4.65.2192
12083.4.65.220/3083.4.65.221 to 83.4.65.22283.4.65.2232
12183.4.65.224/3083.4.65.225 to 83.4.65.22683.4.65.2272
12283.4.65.228/3083.4.65.229 to 83.4.65.23083.4.65.2312
12383.4.65.232/3083.4.65.233 to 83.4.65.23483.4.65.2352
12483.4.65.236/3083.4.65.237 to 83.4.65.23883.4.65.2392
12583.4.65.240/3083.4.65.241 to 83.4.65.24283.4.65.2432
12683.4.65.244/3083.4.65.245 to 83.4.65.24683.4.65.2472
12783.4.65.248/3083.4.65.249 to 83.4.65.25083.4.65.2512
12883.4.65.252/3083.4.65.253 to 83.4.65.25483.4.65.2552
12983.4.66.0/3083.4.66.1 to 83.4.66.283.4.66.32
13083.4.66.4/3083.4.66.5 to 83.4.66.683.4.66.72
13183.4.66.8/3083.4.66.9 to 83.4.66.1083.4.66.112
13283.4.66.12/3083.4.66.13 to 83.4.66.1483.4.66.152
13383.4.66.16/3083.4.66.17 to 83.4.66.1883.4.66.192
13483.4.66.20/3083.4.66.21 to 83.4.66.2283.4.66.232
13583.4.66.24/3083.4.66.25 to 83.4.66.2683.4.66.272
13683.4.66.28/3083.4.66.29 to 83.4.66.3083.4.66.312
13783.4.66.32/3083.4.66.33 to 83.4.66.3483.4.66.352
13883.4.66.36/3083.4.66.37 to 83.4.66.3883.4.66.392
13983.4.66.40/3083.4.66.41 to 83.4.66.4283.4.66.432
14083.4.66.44/3083.4.66.45 to 83.4.66.4683.4.66.472
14183.4.66.48/3083.4.66.49 to 83.4.66.5083.4.66.512
14283.4.66.52/3083.4.66.53 to 83.4.66.5483.4.66.552
14383.4.66.56/3083.4.66.57 to 83.4.66.5883.4.66.592
14483.4.66.60/3083.4.66.61 to 83.4.66.6283.4.66.632
14583.4.66.64/3083.4.66.65 to 83.4.66.6683.4.66.672
14683.4.66.68/3083.4.66.69 to 83.4.66.7083.4.66.712
14783.4.66.72/3083.4.66.73 to 83.4.66.7483.4.66.752
14883.4.66.76/3083.4.66.77 to 83.4.66.7883.4.66.792
14983.4.66.80/3083.4.66.81 to 83.4.66.8283.4.66.832
15083.4.66.84/3083.4.66.85 to 83.4.66.8683.4.66.872
15183.4.66.88/3083.4.66.89 to 83.4.66.9083.4.66.912
15283.4.66.92/3083.4.66.93 to 83.4.66.9483.4.66.952
15383.4.66.96/3083.4.66.97 to 83.4.66.9883.4.66.992
15483.4.66.100/3083.4.66.101 to 83.4.66.10283.4.66.1032
15583.4.66.104/3083.4.66.105 to 83.4.66.10683.4.66.1072
15683.4.66.108/3083.4.66.109 to 83.4.66.11083.4.66.1112
15783.4.66.112/3083.4.66.113 to 83.4.66.11483.4.66.1152
15883.4.66.116/3083.4.66.117 to 83.4.66.11883.4.66.1192
15983.4.66.120/3083.4.66.121 to 83.4.66.12283.4.66.1232
16083.4.66.124/3083.4.66.125 to 83.4.66.12683.4.66.1272
16183.4.66.128/3083.4.66.129 to 83.4.66.13083.4.66.1312
16283.4.66.132/3083.4.66.133 to 83.4.66.13483.4.66.1352
16383.4.66.136/3083.4.66.137 to 83.4.66.13883.4.66.1392
16483.4.66.140/3083.4.66.141 to 83.4.66.14283.4.66.1432
16583.4.66.144/3083.4.66.145 to 83.4.66.14683.4.66.1472
16683.4.66.148/3083.4.66.149 to 83.4.66.15083.4.66.1512
16783.4.66.152/3083.4.66.153 to 83.4.66.15483.4.66.1552
16883.4.66.156/3083.4.66.157 to 83.4.66.15883.4.66.1592
16983.4.66.160/3083.4.66.161 to 83.4.66.16283.4.66.1632
17083.4.66.164/3083.4.66.165 to 83.4.66.16683.4.66.1672
17183.4.66.168/3083.4.66.169 to 83.4.66.17083.4.66.1712
17283.4.66.172/3083.4.66.173 to 83.4.66.17483.4.66.1752
17383.4.66.176/3083.4.66.177 to 83.4.66.17883.4.66.1792
17483.4.66.180/3083.4.66.181 to 83.4.66.18283.4.66.1832
17583.4.66.184/3083.4.66.185 to 83.4.66.18683.4.66.1872
17683.4.66.188/3083.4.66.189 to 83.4.66.19083.4.66.1912
17783.4.66.192/3083.4.66.193 to 83.4.66.19483.4.66.1952
17883.4.66.196/3083.4.66.197 to 83.4.66.19883.4.66.1992
17983.4.66.200/3083.4.66.201 to 83.4.66.20283.4.66.2032
18083.4.66.204/3083.4.66.205 to 83.4.66.20683.4.66.2072
18183.4.66.208/3083.4.66.209 to 83.4.66.21083.4.66.2112
18283.4.66.212/3083.4.66.213 to 83.4.66.21483.4.66.2152
18383.4.66.216/3083.4.66.217 to 83.4.66.21883.4.66.2192
18483.4.66.220/3083.4.66.221 to 83.4.66.22283.4.66.2232
18583.4.66.224/3083.4.66.225 to 83.4.66.22683.4.66.2272
18683.4.66.228/3083.4.66.229 to 83.4.66.23083.4.66.2312
18783.4.66.232/3083.4.66.233 to 83.4.66.23483.4.66.2352
18883.4.66.236/3083.4.66.237 to 83.4.66.23883.4.66.2392
18983.4.66.240/3083.4.66.241 to 83.4.66.24283.4.66.2432
19083.4.66.244/3083.4.66.245 to 83.4.66.24683.4.66.2472
19183.4.66.248/3083.4.66.249 to 83.4.66.25083.4.66.2512
19283.4.66.252/3083.4.66.253 to 83.4.66.25483.4.66.2552
19383.4.67.0/3083.4.67.1 to 83.4.67.283.4.67.32
19483.4.67.4/3083.4.67.5 to 83.4.67.683.4.67.72
19583.4.67.8/3083.4.67.9 to 83.4.67.1083.4.67.112
19683.4.67.12/3083.4.67.13 to 83.4.67.1483.4.67.152
19783.4.67.16/3083.4.67.17 to 83.4.67.1883.4.67.192
19883.4.67.20/3083.4.67.21 to 83.4.67.2283.4.67.232
19983.4.67.24/3083.4.67.25 to 83.4.67.2683.4.67.272
20083.4.67.28/3083.4.67.29 to 83.4.67.3083.4.67.312
20183.4.67.32/3083.4.67.33 to 83.4.67.3483.4.67.352
20283.4.67.36/3083.4.67.37 to 83.4.67.3883.4.67.392
20383.4.67.40/3083.4.67.41 to 83.4.67.4283.4.67.432
20483.4.67.44/3083.4.67.45 to 83.4.67.4683.4.67.472
20583.4.67.48/3083.4.67.49 to 83.4.67.5083.4.67.512
20683.4.67.52/3083.4.67.53 to 83.4.67.5483.4.67.552
20783.4.67.56/3083.4.67.57 to 83.4.67.5883.4.67.592
20883.4.67.60/3083.4.67.61 to 83.4.67.6283.4.67.632
20983.4.67.64/3083.4.67.65 to 83.4.67.6683.4.67.672
21083.4.67.68/3083.4.67.69 to 83.4.67.7083.4.67.712
21183.4.67.72/3083.4.67.73 to 83.4.67.7483.4.67.752
21283.4.67.76/3083.4.67.77 to 83.4.67.7883.4.67.792
21383.4.67.80/3083.4.67.81 to 83.4.67.8283.4.67.832
21483.4.67.84/3083.4.67.85 to 83.4.67.8683.4.67.872
21583.4.67.88/3083.4.67.89 to 83.4.67.9083.4.67.912
21683.4.67.92/3083.4.67.93 to 83.4.67.9483.4.67.952
21783.4.67.96/3083.4.67.97 to 83.4.67.9883.4.67.992
21883.4.67.100/3083.4.67.101 to 83.4.67.10283.4.67.1032
21983.4.67.104/3083.4.67.105 to 83.4.67.10683.4.67.1072
22083.4.67.108/3083.4.67.109 to 83.4.67.11083.4.67.1112
22183.4.67.112/3083.4.67.113 to 83.4.67.11483.4.67.1152
22283.4.67.116/3083.4.67.117 to 83.4.67.11883.4.67.1192
22383.4.67.120/3083.4.67.121 to 83.4.67.12283.4.67.1232
22483.4.67.124/3083.4.67.125 to 83.4.67.12683.4.67.1272
22583.4.67.128/3083.4.67.129 to 83.4.67.13083.4.67.1312
22683.4.67.132/3083.4.67.133 to 83.4.67.13483.4.67.1352
22783.4.67.136/3083.4.67.137 to 83.4.67.13883.4.67.1392
22883.4.67.140/3083.4.67.141 to 83.4.67.14283.4.67.1432
22983.4.67.144/3083.4.67.145 to 83.4.67.14683.4.67.1472
23083.4.67.148/3083.4.67.149 to 83.4.67.15083.4.67.1512
23183.4.67.152/3083.4.67.153 to 83.4.67.15483.4.67.1552
23283.4.67.156/3083.4.67.157 to 83.4.67.15883.4.67.1592
23383.4.67.160/3083.4.67.161 to 83.4.67.16283.4.67.1632
23483.4.67.164/3083.4.67.165 to 83.4.67.16683.4.67.1672
23583.4.67.168/3083.4.67.169 to 83.4.67.17083.4.67.1712
23683.4.67.172/3083.4.67.173 to 83.4.67.17483.4.67.1752
23783.4.67.176/3083.4.67.177 to 83.4.67.17883.4.67.1792
23883.4.67.180/3083.4.67.181 to 83.4.67.18283.4.67.1832
23983.4.67.184/3083.4.67.185 to 83.4.67.18683.4.67.1872
24083.4.67.188/3083.4.67.189 to 83.4.67.19083.4.67.1912
24183.4.67.192/3083.4.67.193 to 83.4.67.19483.4.67.1952
24283.4.67.196/3083.4.67.197 to 83.4.67.19883.4.67.1992
24383.4.67.200/3083.4.67.201 to 83.4.67.20283.4.67.2032
24483.4.67.204/3083.4.67.205 to 83.4.67.20683.4.67.2072
24583.4.67.208/3083.4.67.209 to 83.4.67.21083.4.67.2112
24683.4.67.212/3083.4.67.213 to 83.4.67.21483.4.67.2152
24783.4.67.216/3083.4.67.217 to 83.4.67.21883.4.67.2192
24883.4.67.220/3083.4.67.221 to 83.4.67.22283.4.67.2232
24983.4.67.224/3083.4.67.225 to 83.4.67.22683.4.67.2272
25083.4.67.228/3083.4.67.229 to 83.4.67.23083.4.67.2312
25183.4.67.232/3083.4.67.233 to 83.4.67.23483.4.67.2352
25283.4.67.236/3083.4.67.237 to 83.4.67.23883.4.67.2392
25383.4.67.240/3083.4.67.241 to 83.4.67.24283.4.67.2432
25483.4.67.244/3083.4.67.245 to 83.4.67.24683.4.67.2472
25583.4.67.248/3083.4.67.249 to 83.4.67.25083.4.67.2512
25683.4.67.252/3083.4.67.253 to 83.4.67.25483.4.67.2552

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.