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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.

Network23.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
23.0.0.0
Broadcast address
23.255.255.255
First usable
23.0.0.1
Last usable
23.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 17000000 · Integer 385875968 to 402653183
Reverse DNS zone
23.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010111..00000000.00000000.0000000023.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00010111..00000000.00000000.0000000023.0.0.0
Broadcast00010111..11111111.11111111.1111111123.255.255.255
Split into smaller subnets/19
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

23.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.0.0.0/1923.0.0.1 to 23.0.31.25423.0.31.2558,190
223.0.32.0/1923.0.32.1 to 23.0.63.25423.0.63.2558,190
323.0.64.0/1923.0.64.1 to 23.0.95.25423.0.95.2558,190
423.0.96.0/1923.0.96.1 to 23.0.127.25423.0.127.2558,190
523.0.128.0/1923.0.128.1 to 23.0.159.25423.0.159.2558,190
623.0.160.0/1923.0.160.1 to 23.0.191.25423.0.191.2558,190
723.0.192.0/1923.0.192.1 to 23.0.223.25423.0.223.2558,190
823.0.224.0/1923.0.224.1 to 23.0.255.25423.0.255.2558,190
923.1.0.0/1923.1.0.1 to 23.1.31.25423.1.31.2558,190
1023.1.32.0/1923.1.32.1 to 23.1.63.25423.1.63.2558,190
1123.1.64.0/1923.1.64.1 to 23.1.95.25423.1.95.2558,190
1223.1.96.0/1923.1.96.1 to 23.1.127.25423.1.127.2558,190
1323.1.128.0/1923.1.128.1 to 23.1.159.25423.1.159.2558,190
1423.1.160.0/1923.1.160.1 to 23.1.191.25423.1.191.2558,190
1523.1.192.0/1923.1.192.1 to 23.1.223.25423.1.223.2558,190
1623.1.224.0/1923.1.224.1 to 23.1.255.25423.1.255.2558,190
1723.2.0.0/1923.2.0.1 to 23.2.31.25423.2.31.2558,190
1823.2.32.0/1923.2.32.1 to 23.2.63.25423.2.63.2558,190
1923.2.64.0/1923.2.64.1 to 23.2.95.25423.2.95.2558,190
2023.2.96.0/1923.2.96.1 to 23.2.127.25423.2.127.2558,190
2123.2.128.0/1923.2.128.1 to 23.2.159.25423.2.159.2558,190
2223.2.160.0/1923.2.160.1 to 23.2.191.25423.2.191.2558,190
2323.2.192.0/1923.2.192.1 to 23.2.223.25423.2.223.2558,190
2423.2.224.0/1923.2.224.1 to 23.2.255.25423.2.255.2558,190
2523.3.0.0/1923.3.0.1 to 23.3.31.25423.3.31.2558,190
2623.3.32.0/1923.3.32.1 to 23.3.63.25423.3.63.2558,190
2723.3.64.0/1923.3.64.1 to 23.3.95.25423.3.95.2558,190
2823.3.96.0/1923.3.96.1 to 23.3.127.25423.3.127.2558,190
2923.3.128.0/1923.3.128.1 to 23.3.159.25423.3.159.2558,190
3023.3.160.0/1923.3.160.1 to 23.3.191.25423.3.191.2558,190
3123.3.192.0/1923.3.192.1 to 23.3.223.25423.3.223.2558,190
3223.3.224.0/1923.3.224.1 to 23.3.255.25423.3.255.2558,190
3323.4.0.0/1923.4.0.1 to 23.4.31.25423.4.31.2558,190
3423.4.32.0/1923.4.32.1 to 23.4.63.25423.4.63.2558,190
3523.4.64.0/1923.4.64.1 to 23.4.95.25423.4.95.2558,190
3623.4.96.0/1923.4.96.1 to 23.4.127.25423.4.127.2558,190
3723.4.128.0/1923.4.128.1 to 23.4.159.25423.4.159.2558,190
3823.4.160.0/1923.4.160.1 to 23.4.191.25423.4.191.2558,190
3923.4.192.0/1923.4.192.1 to 23.4.223.25423.4.223.2558,190
4023.4.224.0/1923.4.224.1 to 23.4.255.25423.4.255.2558,190
4123.5.0.0/1923.5.0.1 to 23.5.31.25423.5.31.2558,190
4223.5.32.0/1923.5.32.1 to 23.5.63.25423.5.63.2558,190
4323.5.64.0/1923.5.64.1 to 23.5.95.25423.5.95.2558,190
4423.5.96.0/1923.5.96.1 to 23.5.127.25423.5.127.2558,190
4523.5.128.0/1923.5.128.1 to 23.5.159.25423.5.159.2558,190
4623.5.160.0/1923.5.160.1 to 23.5.191.25423.5.191.2558,190
4723.5.192.0/1923.5.192.1 to 23.5.223.25423.5.223.2558,190
4823.5.224.0/1923.5.224.1 to 23.5.255.25423.5.255.2558,190
4923.6.0.0/1923.6.0.1 to 23.6.31.25423.6.31.2558,190
5023.6.32.0/1923.6.32.1 to 23.6.63.25423.6.63.2558,190
5123.6.64.0/1923.6.64.1 to 23.6.95.25423.6.95.2558,190
5223.6.96.0/1923.6.96.1 to 23.6.127.25423.6.127.2558,190
5323.6.128.0/1923.6.128.1 to 23.6.159.25423.6.159.2558,190
5423.6.160.0/1923.6.160.1 to 23.6.191.25423.6.191.2558,190
5523.6.192.0/1923.6.192.1 to 23.6.223.25423.6.223.2558,190
5623.6.224.0/1923.6.224.1 to 23.6.255.25423.6.255.2558,190
5723.7.0.0/1923.7.0.1 to 23.7.31.25423.7.31.2558,190
5823.7.32.0/1923.7.32.1 to 23.7.63.25423.7.63.2558,190
5923.7.64.0/1923.7.64.1 to 23.7.95.25423.7.95.2558,190
6023.7.96.0/1923.7.96.1 to 23.7.127.25423.7.127.2558,190
6123.7.128.0/1923.7.128.1 to 23.7.159.25423.7.159.2558,190
6223.7.160.0/1923.7.160.1 to 23.7.191.25423.7.191.2558,190
6323.7.192.0/1923.7.192.1 to 23.7.223.25423.7.223.2558,190
6423.7.224.0/1923.7.224.1 to 23.7.255.25423.7.255.2558,190
6523.8.0.0/1923.8.0.1 to 23.8.31.25423.8.31.2558,190
6623.8.32.0/1923.8.32.1 to 23.8.63.25423.8.63.2558,190
6723.8.64.0/1923.8.64.1 to 23.8.95.25423.8.95.2558,190
6823.8.96.0/1923.8.96.1 to 23.8.127.25423.8.127.2558,190
6923.8.128.0/1923.8.128.1 to 23.8.159.25423.8.159.2558,190
7023.8.160.0/1923.8.160.1 to 23.8.191.25423.8.191.2558,190
7123.8.192.0/1923.8.192.1 to 23.8.223.25423.8.223.2558,190
7223.8.224.0/1923.8.224.1 to 23.8.255.25423.8.255.2558,190
7323.9.0.0/1923.9.0.1 to 23.9.31.25423.9.31.2558,190
7423.9.32.0/1923.9.32.1 to 23.9.63.25423.9.63.2558,190
7523.9.64.0/1923.9.64.1 to 23.9.95.25423.9.95.2558,190
7623.9.96.0/1923.9.96.1 to 23.9.127.25423.9.127.2558,190
7723.9.128.0/1923.9.128.1 to 23.9.159.25423.9.159.2558,190
7823.9.160.0/1923.9.160.1 to 23.9.191.25423.9.191.2558,190
7923.9.192.0/1923.9.192.1 to 23.9.223.25423.9.223.2558,190
8023.9.224.0/1923.9.224.1 to 23.9.255.25423.9.255.2558,190
8123.10.0.0/1923.10.0.1 to 23.10.31.25423.10.31.2558,190
8223.10.32.0/1923.10.32.1 to 23.10.63.25423.10.63.2558,190
8323.10.64.0/1923.10.64.1 to 23.10.95.25423.10.95.2558,190
8423.10.96.0/1923.10.96.1 to 23.10.127.25423.10.127.2558,190
8523.10.128.0/1923.10.128.1 to 23.10.159.25423.10.159.2558,190
8623.10.160.0/1923.10.160.1 to 23.10.191.25423.10.191.2558,190
8723.10.192.0/1923.10.192.1 to 23.10.223.25423.10.223.2558,190
8823.10.224.0/1923.10.224.1 to 23.10.255.25423.10.255.2558,190
8923.11.0.0/1923.11.0.1 to 23.11.31.25423.11.31.2558,190
9023.11.32.0/1923.11.32.1 to 23.11.63.25423.11.63.2558,190
9123.11.64.0/1923.11.64.1 to 23.11.95.25423.11.95.2558,190
9223.11.96.0/1923.11.96.1 to 23.11.127.25423.11.127.2558,190
9323.11.128.0/1923.11.128.1 to 23.11.159.25423.11.159.2558,190
9423.11.160.0/1923.11.160.1 to 23.11.191.25423.11.191.2558,190
9523.11.192.0/1923.11.192.1 to 23.11.223.25423.11.223.2558,190
9623.11.224.0/1923.11.224.1 to 23.11.255.25423.11.255.2558,190
9723.12.0.0/1923.12.0.1 to 23.12.31.25423.12.31.2558,190
9823.12.32.0/1923.12.32.1 to 23.12.63.25423.12.63.2558,190
9923.12.64.0/1923.12.64.1 to 23.12.95.25423.12.95.2558,190
10023.12.96.0/1923.12.96.1 to 23.12.127.25423.12.127.2558,190
10123.12.128.0/1923.12.128.1 to 23.12.159.25423.12.159.2558,190
10223.12.160.0/1923.12.160.1 to 23.12.191.25423.12.191.2558,190
10323.12.192.0/1923.12.192.1 to 23.12.223.25423.12.223.2558,190
10423.12.224.0/1923.12.224.1 to 23.12.255.25423.12.255.2558,190
10523.13.0.0/1923.13.0.1 to 23.13.31.25423.13.31.2558,190
10623.13.32.0/1923.13.32.1 to 23.13.63.25423.13.63.2558,190
10723.13.64.0/1923.13.64.1 to 23.13.95.25423.13.95.2558,190
10823.13.96.0/1923.13.96.1 to 23.13.127.25423.13.127.2558,190
10923.13.128.0/1923.13.128.1 to 23.13.159.25423.13.159.2558,190
11023.13.160.0/1923.13.160.1 to 23.13.191.25423.13.191.2558,190
11123.13.192.0/1923.13.192.1 to 23.13.223.25423.13.223.2558,190
11223.13.224.0/1923.13.224.1 to 23.13.255.25423.13.255.2558,190
11323.14.0.0/1923.14.0.1 to 23.14.31.25423.14.31.2558,190
11423.14.32.0/1923.14.32.1 to 23.14.63.25423.14.63.2558,190
11523.14.64.0/1923.14.64.1 to 23.14.95.25423.14.95.2558,190
11623.14.96.0/1923.14.96.1 to 23.14.127.25423.14.127.2558,190
11723.14.128.0/1923.14.128.1 to 23.14.159.25423.14.159.2558,190
11823.14.160.0/1923.14.160.1 to 23.14.191.25423.14.191.2558,190
11923.14.192.0/1923.14.192.1 to 23.14.223.25423.14.223.2558,190
12023.14.224.0/1923.14.224.1 to 23.14.255.25423.14.255.2558,190
12123.15.0.0/1923.15.0.1 to 23.15.31.25423.15.31.2558,190
12223.15.32.0/1923.15.32.1 to 23.15.63.25423.15.63.2558,190
12323.15.64.0/1923.15.64.1 to 23.15.95.25423.15.95.2558,190
12423.15.96.0/1923.15.96.1 to 23.15.127.25423.15.127.2558,190
12523.15.128.0/1923.15.128.1 to 23.15.159.25423.15.159.2558,190
12623.15.160.0/1923.15.160.1 to 23.15.191.25423.15.191.2558,190
12723.15.192.0/1923.15.192.1 to 23.15.223.25423.15.223.2558,190
12823.15.224.0/1923.15.224.1 to 23.15.255.25423.15.255.2558,190
12923.16.0.0/1923.16.0.1 to 23.16.31.25423.16.31.2558,190
13023.16.32.0/1923.16.32.1 to 23.16.63.25423.16.63.2558,190
13123.16.64.0/1923.16.64.1 to 23.16.95.25423.16.95.2558,190
13223.16.96.0/1923.16.96.1 to 23.16.127.25423.16.127.2558,190
13323.16.128.0/1923.16.128.1 to 23.16.159.25423.16.159.2558,190
13423.16.160.0/1923.16.160.1 to 23.16.191.25423.16.191.2558,190
13523.16.192.0/1923.16.192.1 to 23.16.223.25423.16.223.2558,190
13623.16.224.0/1923.16.224.1 to 23.16.255.25423.16.255.2558,190
13723.17.0.0/1923.17.0.1 to 23.17.31.25423.17.31.2558,190
13823.17.32.0/1923.17.32.1 to 23.17.63.25423.17.63.2558,190
13923.17.64.0/1923.17.64.1 to 23.17.95.25423.17.95.2558,190
14023.17.96.0/1923.17.96.1 to 23.17.127.25423.17.127.2558,190
14123.17.128.0/1923.17.128.1 to 23.17.159.25423.17.159.2558,190
14223.17.160.0/1923.17.160.1 to 23.17.191.25423.17.191.2558,190
14323.17.192.0/1923.17.192.1 to 23.17.223.25423.17.223.2558,190
14423.17.224.0/1923.17.224.1 to 23.17.255.25423.17.255.2558,190
14523.18.0.0/1923.18.0.1 to 23.18.31.25423.18.31.2558,190
14623.18.32.0/1923.18.32.1 to 23.18.63.25423.18.63.2558,190
14723.18.64.0/1923.18.64.1 to 23.18.95.25423.18.95.2558,190
14823.18.96.0/1923.18.96.1 to 23.18.127.25423.18.127.2558,190
14923.18.128.0/1923.18.128.1 to 23.18.159.25423.18.159.2558,190
15023.18.160.0/1923.18.160.1 to 23.18.191.25423.18.191.2558,190
15123.18.192.0/1923.18.192.1 to 23.18.223.25423.18.223.2558,190
15223.18.224.0/1923.18.224.1 to 23.18.255.25423.18.255.2558,190
15323.19.0.0/1923.19.0.1 to 23.19.31.25423.19.31.2558,190
15423.19.32.0/1923.19.32.1 to 23.19.63.25423.19.63.2558,190
15523.19.64.0/1923.19.64.1 to 23.19.95.25423.19.95.2558,190
15623.19.96.0/1923.19.96.1 to 23.19.127.25423.19.127.2558,190
15723.19.128.0/1923.19.128.1 to 23.19.159.25423.19.159.2558,190
15823.19.160.0/1923.19.160.1 to 23.19.191.25423.19.191.2558,190
15923.19.192.0/1923.19.192.1 to 23.19.223.25423.19.223.2558,190
16023.19.224.0/1923.19.224.1 to 23.19.255.25423.19.255.2558,190
16123.20.0.0/1923.20.0.1 to 23.20.31.25423.20.31.2558,190
16223.20.32.0/1923.20.32.1 to 23.20.63.25423.20.63.2558,190
16323.20.64.0/1923.20.64.1 to 23.20.95.25423.20.95.2558,190
16423.20.96.0/1923.20.96.1 to 23.20.127.25423.20.127.2558,190
16523.20.128.0/1923.20.128.1 to 23.20.159.25423.20.159.2558,190
16623.20.160.0/1923.20.160.1 to 23.20.191.25423.20.191.2558,190
16723.20.192.0/1923.20.192.1 to 23.20.223.25423.20.223.2558,190
16823.20.224.0/1923.20.224.1 to 23.20.255.25423.20.255.2558,190
16923.21.0.0/1923.21.0.1 to 23.21.31.25423.21.31.2558,190
17023.21.32.0/1923.21.32.1 to 23.21.63.25423.21.63.2558,190
17123.21.64.0/1923.21.64.1 to 23.21.95.25423.21.95.2558,190
17223.21.96.0/1923.21.96.1 to 23.21.127.25423.21.127.2558,190
17323.21.128.0/1923.21.128.1 to 23.21.159.25423.21.159.2558,190
17423.21.160.0/1923.21.160.1 to 23.21.191.25423.21.191.2558,190
17523.21.192.0/1923.21.192.1 to 23.21.223.25423.21.223.2558,190
17623.21.224.0/1923.21.224.1 to 23.21.255.25423.21.255.2558,190
17723.22.0.0/1923.22.0.1 to 23.22.31.25423.22.31.2558,190
17823.22.32.0/1923.22.32.1 to 23.22.63.25423.22.63.2558,190
17923.22.64.0/1923.22.64.1 to 23.22.95.25423.22.95.2558,190
18023.22.96.0/1923.22.96.1 to 23.22.127.25423.22.127.2558,190
18123.22.128.0/1923.22.128.1 to 23.22.159.25423.22.159.2558,190
18223.22.160.0/1923.22.160.1 to 23.22.191.25423.22.191.2558,190
18323.22.192.0/1923.22.192.1 to 23.22.223.25423.22.223.2558,190
18423.22.224.0/1923.22.224.1 to 23.22.255.25423.22.255.2558,190
18523.23.0.0/1923.23.0.1 to 23.23.31.25423.23.31.2558,190
18623.23.32.0/1923.23.32.1 to 23.23.63.25423.23.63.2558,190
18723.23.64.0/1923.23.64.1 to 23.23.95.25423.23.95.2558,190
18823.23.96.0/1923.23.96.1 to 23.23.127.25423.23.127.2558,190
18923.23.128.0/1923.23.128.1 to 23.23.159.25423.23.159.2558,190
19023.23.160.0/1923.23.160.1 to 23.23.191.25423.23.191.2558,190
19123.23.192.0/1923.23.192.1 to 23.23.223.25423.23.223.2558,190
19223.23.224.0/1923.23.224.1 to 23.23.255.25423.23.255.2558,190
19323.24.0.0/1923.24.0.1 to 23.24.31.25423.24.31.2558,190
19423.24.32.0/1923.24.32.1 to 23.24.63.25423.24.63.2558,190
19523.24.64.0/1923.24.64.1 to 23.24.95.25423.24.95.2558,190
19623.24.96.0/1923.24.96.1 to 23.24.127.25423.24.127.2558,190
19723.24.128.0/1923.24.128.1 to 23.24.159.25423.24.159.2558,190
19823.24.160.0/1923.24.160.1 to 23.24.191.25423.24.191.2558,190
19923.24.192.0/1923.24.192.1 to 23.24.223.25423.24.223.2558,190
20023.24.224.0/1923.24.224.1 to 23.24.255.25423.24.255.2558,190
20123.25.0.0/1923.25.0.1 to 23.25.31.25423.25.31.2558,190
20223.25.32.0/1923.25.32.1 to 23.25.63.25423.25.63.2558,190
20323.25.64.0/1923.25.64.1 to 23.25.95.25423.25.95.2558,190
20423.25.96.0/1923.25.96.1 to 23.25.127.25423.25.127.2558,190
20523.25.128.0/1923.25.128.1 to 23.25.159.25423.25.159.2558,190
20623.25.160.0/1923.25.160.1 to 23.25.191.25423.25.191.2558,190
20723.25.192.0/1923.25.192.1 to 23.25.223.25423.25.223.2558,190
20823.25.224.0/1923.25.224.1 to 23.25.255.25423.25.255.2558,190
20923.26.0.0/1923.26.0.1 to 23.26.31.25423.26.31.2558,190
21023.26.32.0/1923.26.32.1 to 23.26.63.25423.26.63.2558,190
21123.26.64.0/1923.26.64.1 to 23.26.95.25423.26.95.2558,190
21223.26.96.0/1923.26.96.1 to 23.26.127.25423.26.127.2558,190
21323.26.128.0/1923.26.128.1 to 23.26.159.25423.26.159.2558,190
21423.26.160.0/1923.26.160.1 to 23.26.191.25423.26.191.2558,190
21523.26.192.0/1923.26.192.1 to 23.26.223.25423.26.223.2558,190
21623.26.224.0/1923.26.224.1 to 23.26.255.25423.26.255.2558,190
21723.27.0.0/1923.27.0.1 to 23.27.31.25423.27.31.2558,190
21823.27.32.0/1923.27.32.1 to 23.27.63.25423.27.63.2558,190
21923.27.64.0/1923.27.64.1 to 23.27.95.25423.27.95.2558,190
22023.27.96.0/1923.27.96.1 to 23.27.127.25423.27.127.2558,190
22123.27.128.0/1923.27.128.1 to 23.27.159.25423.27.159.2558,190
22223.27.160.0/1923.27.160.1 to 23.27.191.25423.27.191.2558,190
22323.27.192.0/1923.27.192.1 to 23.27.223.25423.27.223.2558,190
22423.27.224.0/1923.27.224.1 to 23.27.255.25423.27.255.2558,190
22523.28.0.0/1923.28.0.1 to 23.28.31.25423.28.31.2558,190
22623.28.32.0/1923.28.32.1 to 23.28.63.25423.28.63.2558,190
22723.28.64.0/1923.28.64.1 to 23.28.95.25423.28.95.2558,190
22823.28.96.0/1923.28.96.1 to 23.28.127.25423.28.127.2558,190
22923.28.128.0/1923.28.128.1 to 23.28.159.25423.28.159.2558,190
23023.28.160.0/1923.28.160.1 to 23.28.191.25423.28.191.2558,190
23123.28.192.0/1923.28.192.1 to 23.28.223.25423.28.223.2558,190
23223.28.224.0/1923.28.224.1 to 23.28.255.25423.28.255.2558,190
23323.29.0.0/1923.29.0.1 to 23.29.31.25423.29.31.2558,190
23423.29.32.0/1923.29.32.1 to 23.29.63.25423.29.63.2558,190
23523.29.64.0/1923.29.64.1 to 23.29.95.25423.29.95.2558,190
23623.29.96.0/1923.29.96.1 to 23.29.127.25423.29.127.2558,190
23723.29.128.0/1923.29.128.1 to 23.29.159.25423.29.159.2558,190
23823.29.160.0/1923.29.160.1 to 23.29.191.25423.29.191.2558,190
23923.29.192.0/1923.29.192.1 to 23.29.223.25423.29.223.2558,190
24023.29.224.0/1923.29.224.1 to 23.29.255.25423.29.255.2558,190
24123.30.0.0/1923.30.0.1 to 23.30.31.25423.30.31.2558,190
24223.30.32.0/1923.30.32.1 to 23.30.63.25423.30.63.2558,190
24323.30.64.0/1923.30.64.1 to 23.30.95.25423.30.95.2558,190
24423.30.96.0/1923.30.96.1 to 23.30.127.25423.30.127.2558,190
24523.30.128.0/1923.30.128.1 to 23.30.159.25423.30.159.2558,190
24623.30.160.0/1923.30.160.1 to 23.30.191.25423.30.191.2558,190
24723.30.192.0/1923.30.192.1 to 23.30.223.25423.30.223.2558,190
24823.30.224.0/1923.30.224.1 to 23.30.255.25423.30.255.2558,190
24923.31.0.0/1923.31.0.1 to 23.31.31.25423.31.31.2558,190
25023.31.32.0/1923.31.32.1 to 23.31.63.25423.31.63.2558,190
25123.31.64.0/1923.31.64.1 to 23.31.95.25423.31.95.2558,190
25223.31.96.0/1923.31.96.1 to 23.31.127.25423.31.127.2558,190
25323.31.128.0/1923.31.128.1 to 23.31.159.25423.31.159.2558,190
25423.31.160.0/1923.31.160.1 to 23.31.191.25423.31.191.2558,190
25523.31.192.0/1923.31.192.1 to 23.31.223.25423.31.223.2558,190
25623.31.224.0/1923.31.224.1 to 23.31.255.25423.31.255.2558,190

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.