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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.

Network68.4.0.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
68.4.0.0
Broadcast address
68.4.15.255
First usable
68.4.0.1
Last usable
68.4.15.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 44040000 · Integer 1141112832 to 1141116927
Reverse DNS zones
0.4.68.in-addr.arpa
1.4.68.in-addr.arpa
2.4.68.in-addr.arpa
3.4.68.in-addr.arpa
4.4.68.in-addr.arpa
5.4.68.in-addr.arpa
6.4.68.in-addr.arpa
7.4.68.in-addr.arpa
8.4.68.in-addr.arpa
9.4.68.in-addr.arpa
10.4.68.in-addr.arpa
11.4.68.in-addr.arpa
12.4.68.in-addr.arpa
13.4.68.in-addr.arpa
14.4.68.in-addr.arpa
15.4.68.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000100.00000100.00000000.0000000068.4.0.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network01000100.00000100.00000000.0000000068.4.0.0
Broadcast01000100.00000100.00001111.1111111168.4.15.255
Split into smaller subnets/30
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

68.4.0.0/20 makes 1,024 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
168.4.0.0/3068.4.0.1 to 68.4.0.268.4.0.32
268.4.0.4/3068.4.0.5 to 68.4.0.668.4.0.72
368.4.0.8/3068.4.0.9 to 68.4.0.1068.4.0.112
468.4.0.12/3068.4.0.13 to 68.4.0.1468.4.0.152
568.4.0.16/3068.4.0.17 to 68.4.0.1868.4.0.192
668.4.0.20/3068.4.0.21 to 68.4.0.2268.4.0.232
768.4.0.24/3068.4.0.25 to 68.4.0.2668.4.0.272
868.4.0.28/3068.4.0.29 to 68.4.0.3068.4.0.312
968.4.0.32/3068.4.0.33 to 68.4.0.3468.4.0.352
1068.4.0.36/3068.4.0.37 to 68.4.0.3868.4.0.392
1168.4.0.40/3068.4.0.41 to 68.4.0.4268.4.0.432
1268.4.0.44/3068.4.0.45 to 68.4.0.4668.4.0.472
1368.4.0.48/3068.4.0.49 to 68.4.0.5068.4.0.512
1468.4.0.52/3068.4.0.53 to 68.4.0.5468.4.0.552
1568.4.0.56/3068.4.0.57 to 68.4.0.5868.4.0.592
1668.4.0.60/3068.4.0.61 to 68.4.0.6268.4.0.632
1768.4.0.64/3068.4.0.65 to 68.4.0.6668.4.0.672
1868.4.0.68/3068.4.0.69 to 68.4.0.7068.4.0.712
1968.4.0.72/3068.4.0.73 to 68.4.0.7468.4.0.752
2068.4.0.76/3068.4.0.77 to 68.4.0.7868.4.0.792
2168.4.0.80/3068.4.0.81 to 68.4.0.8268.4.0.832
2268.4.0.84/3068.4.0.85 to 68.4.0.8668.4.0.872
2368.4.0.88/3068.4.0.89 to 68.4.0.9068.4.0.912
2468.4.0.92/3068.4.0.93 to 68.4.0.9468.4.0.952
2568.4.0.96/3068.4.0.97 to 68.4.0.9868.4.0.992
2668.4.0.100/3068.4.0.101 to 68.4.0.10268.4.0.1032
2768.4.0.104/3068.4.0.105 to 68.4.0.10668.4.0.1072
2868.4.0.108/3068.4.0.109 to 68.4.0.11068.4.0.1112
2968.4.0.112/3068.4.0.113 to 68.4.0.11468.4.0.1152
3068.4.0.116/3068.4.0.117 to 68.4.0.11868.4.0.1192
3168.4.0.120/3068.4.0.121 to 68.4.0.12268.4.0.1232
3268.4.0.124/3068.4.0.125 to 68.4.0.12668.4.0.1272
3368.4.0.128/3068.4.0.129 to 68.4.0.13068.4.0.1312
3468.4.0.132/3068.4.0.133 to 68.4.0.13468.4.0.1352
3568.4.0.136/3068.4.0.137 to 68.4.0.13868.4.0.1392
3668.4.0.140/3068.4.0.141 to 68.4.0.14268.4.0.1432
3768.4.0.144/3068.4.0.145 to 68.4.0.14668.4.0.1472
3868.4.0.148/3068.4.0.149 to 68.4.0.15068.4.0.1512
3968.4.0.152/3068.4.0.153 to 68.4.0.15468.4.0.1552
4068.4.0.156/3068.4.0.157 to 68.4.0.15868.4.0.1592
4168.4.0.160/3068.4.0.161 to 68.4.0.16268.4.0.1632
4268.4.0.164/3068.4.0.165 to 68.4.0.16668.4.0.1672
4368.4.0.168/3068.4.0.169 to 68.4.0.17068.4.0.1712
4468.4.0.172/3068.4.0.173 to 68.4.0.17468.4.0.1752
4568.4.0.176/3068.4.0.177 to 68.4.0.17868.4.0.1792
4668.4.0.180/3068.4.0.181 to 68.4.0.18268.4.0.1832
4768.4.0.184/3068.4.0.185 to 68.4.0.18668.4.0.1872
4868.4.0.188/3068.4.0.189 to 68.4.0.19068.4.0.1912
4968.4.0.192/3068.4.0.193 to 68.4.0.19468.4.0.1952
5068.4.0.196/3068.4.0.197 to 68.4.0.19868.4.0.1992
5168.4.0.200/3068.4.0.201 to 68.4.0.20268.4.0.2032
5268.4.0.204/3068.4.0.205 to 68.4.0.20668.4.0.2072
5368.4.0.208/3068.4.0.209 to 68.4.0.21068.4.0.2112
5468.4.0.212/3068.4.0.213 to 68.4.0.21468.4.0.2152
5568.4.0.216/3068.4.0.217 to 68.4.0.21868.4.0.2192
5668.4.0.220/3068.4.0.221 to 68.4.0.22268.4.0.2232
5768.4.0.224/3068.4.0.225 to 68.4.0.22668.4.0.2272
5868.4.0.228/3068.4.0.229 to 68.4.0.23068.4.0.2312
5968.4.0.232/3068.4.0.233 to 68.4.0.23468.4.0.2352
6068.4.0.236/3068.4.0.237 to 68.4.0.23868.4.0.2392
6168.4.0.240/3068.4.0.241 to 68.4.0.24268.4.0.2432
6268.4.0.244/3068.4.0.245 to 68.4.0.24668.4.0.2472
6368.4.0.248/3068.4.0.249 to 68.4.0.25068.4.0.2512
6468.4.0.252/3068.4.0.253 to 68.4.0.25468.4.0.2552
6568.4.1.0/3068.4.1.1 to 68.4.1.268.4.1.32
6668.4.1.4/3068.4.1.5 to 68.4.1.668.4.1.72
6768.4.1.8/3068.4.1.9 to 68.4.1.1068.4.1.112
6868.4.1.12/3068.4.1.13 to 68.4.1.1468.4.1.152
6968.4.1.16/3068.4.1.17 to 68.4.1.1868.4.1.192
7068.4.1.20/3068.4.1.21 to 68.4.1.2268.4.1.232
7168.4.1.24/3068.4.1.25 to 68.4.1.2668.4.1.272
7268.4.1.28/3068.4.1.29 to 68.4.1.3068.4.1.312
7368.4.1.32/3068.4.1.33 to 68.4.1.3468.4.1.352
7468.4.1.36/3068.4.1.37 to 68.4.1.3868.4.1.392
7568.4.1.40/3068.4.1.41 to 68.4.1.4268.4.1.432
7668.4.1.44/3068.4.1.45 to 68.4.1.4668.4.1.472
7768.4.1.48/3068.4.1.49 to 68.4.1.5068.4.1.512
7868.4.1.52/3068.4.1.53 to 68.4.1.5468.4.1.552
7968.4.1.56/3068.4.1.57 to 68.4.1.5868.4.1.592
8068.4.1.60/3068.4.1.61 to 68.4.1.6268.4.1.632
8168.4.1.64/3068.4.1.65 to 68.4.1.6668.4.1.672
8268.4.1.68/3068.4.1.69 to 68.4.1.7068.4.1.712
8368.4.1.72/3068.4.1.73 to 68.4.1.7468.4.1.752
8468.4.1.76/3068.4.1.77 to 68.4.1.7868.4.1.792
8568.4.1.80/3068.4.1.81 to 68.4.1.8268.4.1.832
8668.4.1.84/3068.4.1.85 to 68.4.1.8668.4.1.872
8768.4.1.88/3068.4.1.89 to 68.4.1.9068.4.1.912
8868.4.1.92/3068.4.1.93 to 68.4.1.9468.4.1.952
8968.4.1.96/3068.4.1.97 to 68.4.1.9868.4.1.992
9068.4.1.100/3068.4.1.101 to 68.4.1.10268.4.1.1032
9168.4.1.104/3068.4.1.105 to 68.4.1.10668.4.1.1072
9268.4.1.108/3068.4.1.109 to 68.4.1.11068.4.1.1112
9368.4.1.112/3068.4.1.113 to 68.4.1.11468.4.1.1152
9468.4.1.116/3068.4.1.117 to 68.4.1.11868.4.1.1192
9568.4.1.120/3068.4.1.121 to 68.4.1.12268.4.1.1232
9668.4.1.124/3068.4.1.125 to 68.4.1.12668.4.1.1272
9768.4.1.128/3068.4.1.129 to 68.4.1.13068.4.1.1312
9868.4.1.132/3068.4.1.133 to 68.4.1.13468.4.1.1352
9968.4.1.136/3068.4.1.137 to 68.4.1.13868.4.1.1392
10068.4.1.140/3068.4.1.141 to 68.4.1.14268.4.1.1432
10168.4.1.144/3068.4.1.145 to 68.4.1.14668.4.1.1472
10268.4.1.148/3068.4.1.149 to 68.4.1.15068.4.1.1512
10368.4.1.152/3068.4.1.153 to 68.4.1.15468.4.1.1552
10468.4.1.156/3068.4.1.157 to 68.4.1.15868.4.1.1592
10568.4.1.160/3068.4.1.161 to 68.4.1.16268.4.1.1632
10668.4.1.164/3068.4.1.165 to 68.4.1.16668.4.1.1672
10768.4.1.168/3068.4.1.169 to 68.4.1.17068.4.1.1712
10868.4.1.172/3068.4.1.173 to 68.4.1.17468.4.1.1752
10968.4.1.176/3068.4.1.177 to 68.4.1.17868.4.1.1792
11068.4.1.180/3068.4.1.181 to 68.4.1.18268.4.1.1832
11168.4.1.184/3068.4.1.185 to 68.4.1.18668.4.1.1872
11268.4.1.188/3068.4.1.189 to 68.4.1.19068.4.1.1912
11368.4.1.192/3068.4.1.193 to 68.4.1.19468.4.1.1952
11468.4.1.196/3068.4.1.197 to 68.4.1.19868.4.1.1992
11568.4.1.200/3068.4.1.201 to 68.4.1.20268.4.1.2032
11668.4.1.204/3068.4.1.205 to 68.4.1.20668.4.1.2072
11768.4.1.208/3068.4.1.209 to 68.4.1.21068.4.1.2112
11868.4.1.212/3068.4.1.213 to 68.4.1.21468.4.1.2152
11968.4.1.216/3068.4.1.217 to 68.4.1.21868.4.1.2192
12068.4.1.220/3068.4.1.221 to 68.4.1.22268.4.1.2232
12168.4.1.224/3068.4.1.225 to 68.4.1.22668.4.1.2272
12268.4.1.228/3068.4.1.229 to 68.4.1.23068.4.1.2312
12368.4.1.232/3068.4.1.233 to 68.4.1.23468.4.1.2352
12468.4.1.236/3068.4.1.237 to 68.4.1.23868.4.1.2392
12568.4.1.240/3068.4.1.241 to 68.4.1.24268.4.1.2432
12668.4.1.244/3068.4.1.245 to 68.4.1.24668.4.1.2472
12768.4.1.248/3068.4.1.249 to 68.4.1.25068.4.1.2512
12868.4.1.252/3068.4.1.253 to 68.4.1.25468.4.1.2552
12968.4.2.0/3068.4.2.1 to 68.4.2.268.4.2.32
13068.4.2.4/3068.4.2.5 to 68.4.2.668.4.2.72
13168.4.2.8/3068.4.2.9 to 68.4.2.1068.4.2.112
13268.4.2.12/3068.4.2.13 to 68.4.2.1468.4.2.152
13368.4.2.16/3068.4.2.17 to 68.4.2.1868.4.2.192
13468.4.2.20/3068.4.2.21 to 68.4.2.2268.4.2.232
13568.4.2.24/3068.4.2.25 to 68.4.2.2668.4.2.272
13668.4.2.28/3068.4.2.29 to 68.4.2.3068.4.2.312
13768.4.2.32/3068.4.2.33 to 68.4.2.3468.4.2.352
13868.4.2.36/3068.4.2.37 to 68.4.2.3868.4.2.392
13968.4.2.40/3068.4.2.41 to 68.4.2.4268.4.2.432
14068.4.2.44/3068.4.2.45 to 68.4.2.4668.4.2.472
14168.4.2.48/3068.4.2.49 to 68.4.2.5068.4.2.512
14268.4.2.52/3068.4.2.53 to 68.4.2.5468.4.2.552
14368.4.2.56/3068.4.2.57 to 68.4.2.5868.4.2.592
14468.4.2.60/3068.4.2.61 to 68.4.2.6268.4.2.632
14568.4.2.64/3068.4.2.65 to 68.4.2.6668.4.2.672
14668.4.2.68/3068.4.2.69 to 68.4.2.7068.4.2.712
14768.4.2.72/3068.4.2.73 to 68.4.2.7468.4.2.752
14868.4.2.76/3068.4.2.77 to 68.4.2.7868.4.2.792
14968.4.2.80/3068.4.2.81 to 68.4.2.8268.4.2.832
15068.4.2.84/3068.4.2.85 to 68.4.2.8668.4.2.872
15168.4.2.88/3068.4.2.89 to 68.4.2.9068.4.2.912
15268.4.2.92/3068.4.2.93 to 68.4.2.9468.4.2.952
15368.4.2.96/3068.4.2.97 to 68.4.2.9868.4.2.992
15468.4.2.100/3068.4.2.101 to 68.4.2.10268.4.2.1032
15568.4.2.104/3068.4.2.105 to 68.4.2.10668.4.2.1072
15668.4.2.108/3068.4.2.109 to 68.4.2.11068.4.2.1112
15768.4.2.112/3068.4.2.113 to 68.4.2.11468.4.2.1152
15868.4.2.116/3068.4.2.117 to 68.4.2.11868.4.2.1192
15968.4.2.120/3068.4.2.121 to 68.4.2.12268.4.2.1232
16068.4.2.124/3068.4.2.125 to 68.4.2.12668.4.2.1272
16168.4.2.128/3068.4.2.129 to 68.4.2.13068.4.2.1312
16268.4.2.132/3068.4.2.133 to 68.4.2.13468.4.2.1352
16368.4.2.136/3068.4.2.137 to 68.4.2.13868.4.2.1392
16468.4.2.140/3068.4.2.141 to 68.4.2.14268.4.2.1432
16568.4.2.144/3068.4.2.145 to 68.4.2.14668.4.2.1472
16668.4.2.148/3068.4.2.149 to 68.4.2.15068.4.2.1512
16768.4.2.152/3068.4.2.153 to 68.4.2.15468.4.2.1552
16868.4.2.156/3068.4.2.157 to 68.4.2.15868.4.2.1592
16968.4.2.160/3068.4.2.161 to 68.4.2.16268.4.2.1632
17068.4.2.164/3068.4.2.165 to 68.4.2.16668.4.2.1672
17168.4.2.168/3068.4.2.169 to 68.4.2.17068.4.2.1712
17268.4.2.172/3068.4.2.173 to 68.4.2.17468.4.2.1752
17368.4.2.176/3068.4.2.177 to 68.4.2.17868.4.2.1792
17468.4.2.180/3068.4.2.181 to 68.4.2.18268.4.2.1832
17568.4.2.184/3068.4.2.185 to 68.4.2.18668.4.2.1872
17668.4.2.188/3068.4.2.189 to 68.4.2.19068.4.2.1912
17768.4.2.192/3068.4.2.193 to 68.4.2.19468.4.2.1952
17868.4.2.196/3068.4.2.197 to 68.4.2.19868.4.2.1992
17968.4.2.200/3068.4.2.201 to 68.4.2.20268.4.2.2032
18068.4.2.204/3068.4.2.205 to 68.4.2.20668.4.2.2072
18168.4.2.208/3068.4.2.209 to 68.4.2.21068.4.2.2112
18268.4.2.212/3068.4.2.213 to 68.4.2.21468.4.2.2152
18368.4.2.216/3068.4.2.217 to 68.4.2.21868.4.2.2192
18468.4.2.220/3068.4.2.221 to 68.4.2.22268.4.2.2232
18568.4.2.224/3068.4.2.225 to 68.4.2.22668.4.2.2272
18668.4.2.228/3068.4.2.229 to 68.4.2.23068.4.2.2312
18768.4.2.232/3068.4.2.233 to 68.4.2.23468.4.2.2352
18868.4.2.236/3068.4.2.237 to 68.4.2.23868.4.2.2392
18968.4.2.240/3068.4.2.241 to 68.4.2.24268.4.2.2432
19068.4.2.244/3068.4.2.245 to 68.4.2.24668.4.2.2472
19168.4.2.248/3068.4.2.249 to 68.4.2.25068.4.2.2512
19268.4.2.252/3068.4.2.253 to 68.4.2.25468.4.2.2552
19368.4.3.0/3068.4.3.1 to 68.4.3.268.4.3.32
19468.4.3.4/3068.4.3.5 to 68.4.3.668.4.3.72
19568.4.3.8/3068.4.3.9 to 68.4.3.1068.4.3.112
19668.4.3.12/3068.4.3.13 to 68.4.3.1468.4.3.152
19768.4.3.16/3068.4.3.17 to 68.4.3.1868.4.3.192
19868.4.3.20/3068.4.3.21 to 68.4.3.2268.4.3.232
19968.4.3.24/3068.4.3.25 to 68.4.3.2668.4.3.272
20068.4.3.28/3068.4.3.29 to 68.4.3.3068.4.3.312
20168.4.3.32/3068.4.3.33 to 68.4.3.3468.4.3.352
20268.4.3.36/3068.4.3.37 to 68.4.3.3868.4.3.392
20368.4.3.40/3068.4.3.41 to 68.4.3.4268.4.3.432
20468.4.3.44/3068.4.3.45 to 68.4.3.4668.4.3.472
20568.4.3.48/3068.4.3.49 to 68.4.3.5068.4.3.512
20668.4.3.52/3068.4.3.53 to 68.4.3.5468.4.3.552
20768.4.3.56/3068.4.3.57 to 68.4.3.5868.4.3.592
20868.4.3.60/3068.4.3.61 to 68.4.3.6268.4.3.632
20968.4.3.64/3068.4.3.65 to 68.4.3.6668.4.3.672
21068.4.3.68/3068.4.3.69 to 68.4.3.7068.4.3.712
21168.4.3.72/3068.4.3.73 to 68.4.3.7468.4.3.752
21268.4.3.76/3068.4.3.77 to 68.4.3.7868.4.3.792
21368.4.3.80/3068.4.3.81 to 68.4.3.8268.4.3.832
21468.4.3.84/3068.4.3.85 to 68.4.3.8668.4.3.872
21568.4.3.88/3068.4.3.89 to 68.4.3.9068.4.3.912
21668.4.3.92/3068.4.3.93 to 68.4.3.9468.4.3.952
21768.4.3.96/3068.4.3.97 to 68.4.3.9868.4.3.992
21868.4.3.100/3068.4.3.101 to 68.4.3.10268.4.3.1032
21968.4.3.104/3068.4.3.105 to 68.4.3.10668.4.3.1072
22068.4.3.108/3068.4.3.109 to 68.4.3.11068.4.3.1112
22168.4.3.112/3068.4.3.113 to 68.4.3.11468.4.3.1152
22268.4.3.116/3068.4.3.117 to 68.4.3.11868.4.3.1192
22368.4.3.120/3068.4.3.121 to 68.4.3.12268.4.3.1232
22468.4.3.124/3068.4.3.125 to 68.4.3.12668.4.3.1272
22568.4.3.128/3068.4.3.129 to 68.4.3.13068.4.3.1312
22668.4.3.132/3068.4.3.133 to 68.4.3.13468.4.3.1352
22768.4.3.136/3068.4.3.137 to 68.4.3.13868.4.3.1392
22868.4.3.140/3068.4.3.141 to 68.4.3.14268.4.3.1432
22968.4.3.144/3068.4.3.145 to 68.4.3.14668.4.3.1472
23068.4.3.148/3068.4.3.149 to 68.4.3.15068.4.3.1512
23168.4.3.152/3068.4.3.153 to 68.4.3.15468.4.3.1552
23268.4.3.156/3068.4.3.157 to 68.4.3.15868.4.3.1592
23368.4.3.160/3068.4.3.161 to 68.4.3.16268.4.3.1632
23468.4.3.164/3068.4.3.165 to 68.4.3.16668.4.3.1672
23568.4.3.168/3068.4.3.169 to 68.4.3.17068.4.3.1712
23668.4.3.172/3068.4.3.173 to 68.4.3.17468.4.3.1752
23768.4.3.176/3068.4.3.177 to 68.4.3.17868.4.3.1792
23868.4.3.180/3068.4.3.181 to 68.4.3.18268.4.3.1832
23968.4.3.184/3068.4.3.185 to 68.4.3.18668.4.3.1872
24068.4.3.188/3068.4.3.189 to 68.4.3.19068.4.3.1912
24168.4.3.192/3068.4.3.193 to 68.4.3.19468.4.3.1952
24268.4.3.196/3068.4.3.197 to 68.4.3.19868.4.3.1992
24368.4.3.200/3068.4.3.201 to 68.4.3.20268.4.3.2032
24468.4.3.204/3068.4.3.205 to 68.4.3.20668.4.3.2072
24568.4.3.208/3068.4.3.209 to 68.4.3.21068.4.3.2112
24668.4.3.212/3068.4.3.213 to 68.4.3.21468.4.3.2152
24768.4.3.216/3068.4.3.217 to 68.4.3.21868.4.3.2192
24868.4.3.220/3068.4.3.221 to 68.4.3.22268.4.3.2232
24968.4.3.224/3068.4.3.225 to 68.4.3.22668.4.3.2272
25068.4.3.228/3068.4.3.229 to 68.4.3.23068.4.3.2312
25168.4.3.232/3068.4.3.233 to 68.4.3.23468.4.3.2352
25268.4.3.236/3068.4.3.237 to 68.4.3.23868.4.3.2392
25368.4.3.240/3068.4.3.241 to 68.4.3.24268.4.3.2432
25468.4.3.244/3068.4.3.245 to 68.4.3.24668.4.3.2472
25568.4.3.248/3068.4.3.249 to 68.4.3.25068.4.3.2512
25668.4.3.252/3068.4.3.253 to 68.4.3.25468.4.3.2552

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.