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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.

Network33.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
33.0.0.0
Broadcast address
33.255.255.255
First usable
33.0.0.1
Last usable
33.255.255.254
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 21000000 · Integer 553648128 to 570425343
Reverse DNS zone
33.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00100001..00000000.00000000.0000000033.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00100001..00000000.00000000.0000000033.0.0.0
Broadcast00100001..11111111.11111111.1111111133.255.255.255
Split into smaller subnets/18
/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)

33.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
133.0.0.0/1833.0.0.1 to 33.0.63.25433.0.63.25516,382
233.0.64.0/1833.0.64.1 to 33.0.127.25433.0.127.25516,382
333.0.128.0/1833.0.128.1 to 33.0.191.25433.0.191.25516,382
433.0.192.0/1833.0.192.1 to 33.0.255.25433.0.255.25516,382
533.1.0.0/1833.1.0.1 to 33.1.63.25433.1.63.25516,382
633.1.64.0/1833.1.64.1 to 33.1.127.25433.1.127.25516,382
733.1.128.0/1833.1.128.1 to 33.1.191.25433.1.191.25516,382
833.1.192.0/1833.1.192.1 to 33.1.255.25433.1.255.25516,382
933.2.0.0/1833.2.0.1 to 33.2.63.25433.2.63.25516,382
1033.2.64.0/1833.2.64.1 to 33.2.127.25433.2.127.25516,382
1133.2.128.0/1833.2.128.1 to 33.2.191.25433.2.191.25516,382
1233.2.192.0/1833.2.192.1 to 33.2.255.25433.2.255.25516,382
1333.3.0.0/1833.3.0.1 to 33.3.63.25433.3.63.25516,382
1433.3.64.0/1833.3.64.1 to 33.3.127.25433.3.127.25516,382
1533.3.128.0/1833.3.128.1 to 33.3.191.25433.3.191.25516,382
1633.3.192.0/1833.3.192.1 to 33.3.255.25433.3.255.25516,382
1733.4.0.0/1833.4.0.1 to 33.4.63.25433.4.63.25516,382
1833.4.64.0/1833.4.64.1 to 33.4.127.25433.4.127.25516,382
1933.4.128.0/1833.4.128.1 to 33.4.191.25433.4.191.25516,382
2033.4.192.0/1833.4.192.1 to 33.4.255.25433.4.255.25516,382
2133.5.0.0/1833.5.0.1 to 33.5.63.25433.5.63.25516,382
2233.5.64.0/1833.5.64.1 to 33.5.127.25433.5.127.25516,382
2333.5.128.0/1833.5.128.1 to 33.5.191.25433.5.191.25516,382
2433.5.192.0/1833.5.192.1 to 33.5.255.25433.5.255.25516,382
2533.6.0.0/1833.6.0.1 to 33.6.63.25433.6.63.25516,382
2633.6.64.0/1833.6.64.1 to 33.6.127.25433.6.127.25516,382
2733.6.128.0/1833.6.128.1 to 33.6.191.25433.6.191.25516,382
2833.6.192.0/1833.6.192.1 to 33.6.255.25433.6.255.25516,382
2933.7.0.0/1833.7.0.1 to 33.7.63.25433.7.63.25516,382
3033.7.64.0/1833.7.64.1 to 33.7.127.25433.7.127.25516,382
3133.7.128.0/1833.7.128.1 to 33.7.191.25433.7.191.25516,382
3233.7.192.0/1833.7.192.1 to 33.7.255.25433.7.255.25516,382
3333.8.0.0/1833.8.0.1 to 33.8.63.25433.8.63.25516,382
3433.8.64.0/1833.8.64.1 to 33.8.127.25433.8.127.25516,382
3533.8.128.0/1833.8.128.1 to 33.8.191.25433.8.191.25516,382
3633.8.192.0/1833.8.192.1 to 33.8.255.25433.8.255.25516,382
3733.9.0.0/1833.9.0.1 to 33.9.63.25433.9.63.25516,382
3833.9.64.0/1833.9.64.1 to 33.9.127.25433.9.127.25516,382
3933.9.128.0/1833.9.128.1 to 33.9.191.25433.9.191.25516,382
4033.9.192.0/1833.9.192.1 to 33.9.255.25433.9.255.25516,382
4133.10.0.0/1833.10.0.1 to 33.10.63.25433.10.63.25516,382
4233.10.64.0/1833.10.64.1 to 33.10.127.25433.10.127.25516,382
4333.10.128.0/1833.10.128.1 to 33.10.191.25433.10.191.25516,382
4433.10.192.0/1833.10.192.1 to 33.10.255.25433.10.255.25516,382
4533.11.0.0/1833.11.0.1 to 33.11.63.25433.11.63.25516,382
4633.11.64.0/1833.11.64.1 to 33.11.127.25433.11.127.25516,382
4733.11.128.0/1833.11.128.1 to 33.11.191.25433.11.191.25516,382
4833.11.192.0/1833.11.192.1 to 33.11.255.25433.11.255.25516,382
4933.12.0.0/1833.12.0.1 to 33.12.63.25433.12.63.25516,382
5033.12.64.0/1833.12.64.1 to 33.12.127.25433.12.127.25516,382
5133.12.128.0/1833.12.128.1 to 33.12.191.25433.12.191.25516,382
5233.12.192.0/1833.12.192.1 to 33.12.255.25433.12.255.25516,382
5333.13.0.0/1833.13.0.1 to 33.13.63.25433.13.63.25516,382
5433.13.64.0/1833.13.64.1 to 33.13.127.25433.13.127.25516,382
5533.13.128.0/1833.13.128.1 to 33.13.191.25433.13.191.25516,382
5633.13.192.0/1833.13.192.1 to 33.13.255.25433.13.255.25516,382
5733.14.0.0/1833.14.0.1 to 33.14.63.25433.14.63.25516,382
5833.14.64.0/1833.14.64.1 to 33.14.127.25433.14.127.25516,382
5933.14.128.0/1833.14.128.1 to 33.14.191.25433.14.191.25516,382
6033.14.192.0/1833.14.192.1 to 33.14.255.25433.14.255.25516,382
6133.15.0.0/1833.15.0.1 to 33.15.63.25433.15.63.25516,382
6233.15.64.0/1833.15.64.1 to 33.15.127.25433.15.127.25516,382
6333.15.128.0/1833.15.128.1 to 33.15.191.25433.15.191.25516,382
6433.15.192.0/1833.15.192.1 to 33.15.255.25433.15.255.25516,382
6533.16.0.0/1833.16.0.1 to 33.16.63.25433.16.63.25516,382
6633.16.64.0/1833.16.64.1 to 33.16.127.25433.16.127.25516,382
6733.16.128.0/1833.16.128.1 to 33.16.191.25433.16.191.25516,382
6833.16.192.0/1833.16.192.1 to 33.16.255.25433.16.255.25516,382
6933.17.0.0/1833.17.0.1 to 33.17.63.25433.17.63.25516,382
7033.17.64.0/1833.17.64.1 to 33.17.127.25433.17.127.25516,382
7133.17.128.0/1833.17.128.1 to 33.17.191.25433.17.191.25516,382
7233.17.192.0/1833.17.192.1 to 33.17.255.25433.17.255.25516,382
7333.18.0.0/1833.18.0.1 to 33.18.63.25433.18.63.25516,382
7433.18.64.0/1833.18.64.1 to 33.18.127.25433.18.127.25516,382
7533.18.128.0/1833.18.128.1 to 33.18.191.25433.18.191.25516,382
7633.18.192.0/1833.18.192.1 to 33.18.255.25433.18.255.25516,382
7733.19.0.0/1833.19.0.1 to 33.19.63.25433.19.63.25516,382
7833.19.64.0/1833.19.64.1 to 33.19.127.25433.19.127.25516,382
7933.19.128.0/1833.19.128.1 to 33.19.191.25433.19.191.25516,382
8033.19.192.0/1833.19.192.1 to 33.19.255.25433.19.255.25516,382
8133.20.0.0/1833.20.0.1 to 33.20.63.25433.20.63.25516,382
8233.20.64.0/1833.20.64.1 to 33.20.127.25433.20.127.25516,382
8333.20.128.0/1833.20.128.1 to 33.20.191.25433.20.191.25516,382
8433.20.192.0/1833.20.192.1 to 33.20.255.25433.20.255.25516,382
8533.21.0.0/1833.21.0.1 to 33.21.63.25433.21.63.25516,382
8633.21.64.0/1833.21.64.1 to 33.21.127.25433.21.127.25516,382
8733.21.128.0/1833.21.128.1 to 33.21.191.25433.21.191.25516,382
8833.21.192.0/1833.21.192.1 to 33.21.255.25433.21.255.25516,382
8933.22.0.0/1833.22.0.1 to 33.22.63.25433.22.63.25516,382
9033.22.64.0/1833.22.64.1 to 33.22.127.25433.22.127.25516,382
9133.22.128.0/1833.22.128.1 to 33.22.191.25433.22.191.25516,382
9233.22.192.0/1833.22.192.1 to 33.22.255.25433.22.255.25516,382
9333.23.0.0/1833.23.0.1 to 33.23.63.25433.23.63.25516,382
9433.23.64.0/1833.23.64.1 to 33.23.127.25433.23.127.25516,382
9533.23.128.0/1833.23.128.1 to 33.23.191.25433.23.191.25516,382
9633.23.192.0/1833.23.192.1 to 33.23.255.25433.23.255.25516,382
9733.24.0.0/1833.24.0.1 to 33.24.63.25433.24.63.25516,382
9833.24.64.0/1833.24.64.1 to 33.24.127.25433.24.127.25516,382
9933.24.128.0/1833.24.128.1 to 33.24.191.25433.24.191.25516,382
10033.24.192.0/1833.24.192.1 to 33.24.255.25433.24.255.25516,382
10133.25.0.0/1833.25.0.1 to 33.25.63.25433.25.63.25516,382
10233.25.64.0/1833.25.64.1 to 33.25.127.25433.25.127.25516,382
10333.25.128.0/1833.25.128.1 to 33.25.191.25433.25.191.25516,382
10433.25.192.0/1833.25.192.1 to 33.25.255.25433.25.255.25516,382
10533.26.0.0/1833.26.0.1 to 33.26.63.25433.26.63.25516,382
10633.26.64.0/1833.26.64.1 to 33.26.127.25433.26.127.25516,382
10733.26.128.0/1833.26.128.1 to 33.26.191.25433.26.191.25516,382
10833.26.192.0/1833.26.192.1 to 33.26.255.25433.26.255.25516,382
10933.27.0.0/1833.27.0.1 to 33.27.63.25433.27.63.25516,382
11033.27.64.0/1833.27.64.1 to 33.27.127.25433.27.127.25516,382
11133.27.128.0/1833.27.128.1 to 33.27.191.25433.27.191.25516,382
11233.27.192.0/1833.27.192.1 to 33.27.255.25433.27.255.25516,382
11333.28.0.0/1833.28.0.1 to 33.28.63.25433.28.63.25516,382
11433.28.64.0/1833.28.64.1 to 33.28.127.25433.28.127.25516,382
11533.28.128.0/1833.28.128.1 to 33.28.191.25433.28.191.25516,382
11633.28.192.0/1833.28.192.1 to 33.28.255.25433.28.255.25516,382
11733.29.0.0/1833.29.0.1 to 33.29.63.25433.29.63.25516,382
11833.29.64.0/1833.29.64.1 to 33.29.127.25433.29.127.25516,382
11933.29.128.0/1833.29.128.1 to 33.29.191.25433.29.191.25516,382
12033.29.192.0/1833.29.192.1 to 33.29.255.25433.29.255.25516,382
12133.30.0.0/1833.30.0.1 to 33.30.63.25433.30.63.25516,382
12233.30.64.0/1833.30.64.1 to 33.30.127.25433.30.127.25516,382
12333.30.128.0/1833.30.128.1 to 33.30.191.25433.30.191.25516,382
12433.30.192.0/1833.30.192.1 to 33.30.255.25433.30.255.25516,382
12533.31.0.0/1833.31.0.1 to 33.31.63.25433.31.63.25516,382
12633.31.64.0/1833.31.64.1 to 33.31.127.25433.31.127.25516,382
12733.31.128.0/1833.31.128.1 to 33.31.191.25433.31.191.25516,382
12833.31.192.0/1833.31.192.1 to 33.31.255.25433.31.255.25516,382
12933.32.0.0/1833.32.0.1 to 33.32.63.25433.32.63.25516,382
13033.32.64.0/1833.32.64.1 to 33.32.127.25433.32.127.25516,382
13133.32.128.0/1833.32.128.1 to 33.32.191.25433.32.191.25516,382
13233.32.192.0/1833.32.192.1 to 33.32.255.25433.32.255.25516,382
13333.33.0.0/1833.33.0.1 to 33.33.63.25433.33.63.25516,382
13433.33.64.0/1833.33.64.1 to 33.33.127.25433.33.127.25516,382
13533.33.128.0/1833.33.128.1 to 33.33.191.25433.33.191.25516,382
13633.33.192.0/1833.33.192.1 to 33.33.255.25433.33.255.25516,382
13733.34.0.0/1833.34.0.1 to 33.34.63.25433.34.63.25516,382
13833.34.64.0/1833.34.64.1 to 33.34.127.25433.34.127.25516,382
13933.34.128.0/1833.34.128.1 to 33.34.191.25433.34.191.25516,382
14033.34.192.0/1833.34.192.1 to 33.34.255.25433.34.255.25516,382
14133.35.0.0/1833.35.0.1 to 33.35.63.25433.35.63.25516,382
14233.35.64.0/1833.35.64.1 to 33.35.127.25433.35.127.25516,382
14333.35.128.0/1833.35.128.1 to 33.35.191.25433.35.191.25516,382
14433.35.192.0/1833.35.192.1 to 33.35.255.25433.35.255.25516,382
14533.36.0.0/1833.36.0.1 to 33.36.63.25433.36.63.25516,382
14633.36.64.0/1833.36.64.1 to 33.36.127.25433.36.127.25516,382
14733.36.128.0/1833.36.128.1 to 33.36.191.25433.36.191.25516,382
14833.36.192.0/1833.36.192.1 to 33.36.255.25433.36.255.25516,382
14933.37.0.0/1833.37.0.1 to 33.37.63.25433.37.63.25516,382
15033.37.64.0/1833.37.64.1 to 33.37.127.25433.37.127.25516,382
15133.37.128.0/1833.37.128.1 to 33.37.191.25433.37.191.25516,382
15233.37.192.0/1833.37.192.1 to 33.37.255.25433.37.255.25516,382
15333.38.0.0/1833.38.0.1 to 33.38.63.25433.38.63.25516,382
15433.38.64.0/1833.38.64.1 to 33.38.127.25433.38.127.25516,382
15533.38.128.0/1833.38.128.1 to 33.38.191.25433.38.191.25516,382
15633.38.192.0/1833.38.192.1 to 33.38.255.25433.38.255.25516,382
15733.39.0.0/1833.39.0.1 to 33.39.63.25433.39.63.25516,382
15833.39.64.0/1833.39.64.1 to 33.39.127.25433.39.127.25516,382
15933.39.128.0/1833.39.128.1 to 33.39.191.25433.39.191.25516,382
16033.39.192.0/1833.39.192.1 to 33.39.255.25433.39.255.25516,382
16133.40.0.0/1833.40.0.1 to 33.40.63.25433.40.63.25516,382
16233.40.64.0/1833.40.64.1 to 33.40.127.25433.40.127.25516,382
16333.40.128.0/1833.40.128.1 to 33.40.191.25433.40.191.25516,382
16433.40.192.0/1833.40.192.1 to 33.40.255.25433.40.255.25516,382
16533.41.0.0/1833.41.0.1 to 33.41.63.25433.41.63.25516,382
16633.41.64.0/1833.41.64.1 to 33.41.127.25433.41.127.25516,382
16733.41.128.0/1833.41.128.1 to 33.41.191.25433.41.191.25516,382
16833.41.192.0/1833.41.192.1 to 33.41.255.25433.41.255.25516,382
16933.42.0.0/1833.42.0.1 to 33.42.63.25433.42.63.25516,382
17033.42.64.0/1833.42.64.1 to 33.42.127.25433.42.127.25516,382
17133.42.128.0/1833.42.128.1 to 33.42.191.25433.42.191.25516,382
17233.42.192.0/1833.42.192.1 to 33.42.255.25433.42.255.25516,382
17333.43.0.0/1833.43.0.1 to 33.43.63.25433.43.63.25516,382
17433.43.64.0/1833.43.64.1 to 33.43.127.25433.43.127.25516,382
17533.43.128.0/1833.43.128.1 to 33.43.191.25433.43.191.25516,382
17633.43.192.0/1833.43.192.1 to 33.43.255.25433.43.255.25516,382
17733.44.0.0/1833.44.0.1 to 33.44.63.25433.44.63.25516,382
17833.44.64.0/1833.44.64.1 to 33.44.127.25433.44.127.25516,382
17933.44.128.0/1833.44.128.1 to 33.44.191.25433.44.191.25516,382
18033.44.192.0/1833.44.192.1 to 33.44.255.25433.44.255.25516,382
18133.45.0.0/1833.45.0.1 to 33.45.63.25433.45.63.25516,382
18233.45.64.0/1833.45.64.1 to 33.45.127.25433.45.127.25516,382
18333.45.128.0/1833.45.128.1 to 33.45.191.25433.45.191.25516,382
18433.45.192.0/1833.45.192.1 to 33.45.255.25433.45.255.25516,382
18533.46.0.0/1833.46.0.1 to 33.46.63.25433.46.63.25516,382
18633.46.64.0/1833.46.64.1 to 33.46.127.25433.46.127.25516,382
18733.46.128.0/1833.46.128.1 to 33.46.191.25433.46.191.25516,382
18833.46.192.0/1833.46.192.1 to 33.46.255.25433.46.255.25516,382
18933.47.0.0/1833.47.0.1 to 33.47.63.25433.47.63.25516,382
19033.47.64.0/1833.47.64.1 to 33.47.127.25433.47.127.25516,382
19133.47.128.0/1833.47.128.1 to 33.47.191.25433.47.191.25516,382
19233.47.192.0/1833.47.192.1 to 33.47.255.25433.47.255.25516,382
19333.48.0.0/1833.48.0.1 to 33.48.63.25433.48.63.25516,382
19433.48.64.0/1833.48.64.1 to 33.48.127.25433.48.127.25516,382
19533.48.128.0/1833.48.128.1 to 33.48.191.25433.48.191.25516,382
19633.48.192.0/1833.48.192.1 to 33.48.255.25433.48.255.25516,382
19733.49.0.0/1833.49.0.1 to 33.49.63.25433.49.63.25516,382
19833.49.64.0/1833.49.64.1 to 33.49.127.25433.49.127.25516,382
19933.49.128.0/1833.49.128.1 to 33.49.191.25433.49.191.25516,382
20033.49.192.0/1833.49.192.1 to 33.49.255.25433.49.255.25516,382
20133.50.0.0/1833.50.0.1 to 33.50.63.25433.50.63.25516,382
20233.50.64.0/1833.50.64.1 to 33.50.127.25433.50.127.25516,382
20333.50.128.0/1833.50.128.1 to 33.50.191.25433.50.191.25516,382
20433.50.192.0/1833.50.192.1 to 33.50.255.25433.50.255.25516,382
20533.51.0.0/1833.51.0.1 to 33.51.63.25433.51.63.25516,382
20633.51.64.0/1833.51.64.1 to 33.51.127.25433.51.127.25516,382
20733.51.128.0/1833.51.128.1 to 33.51.191.25433.51.191.25516,382
20833.51.192.0/1833.51.192.1 to 33.51.255.25433.51.255.25516,382
20933.52.0.0/1833.52.0.1 to 33.52.63.25433.52.63.25516,382
21033.52.64.0/1833.52.64.1 to 33.52.127.25433.52.127.25516,382
21133.52.128.0/1833.52.128.1 to 33.52.191.25433.52.191.25516,382
21233.52.192.0/1833.52.192.1 to 33.52.255.25433.52.255.25516,382
21333.53.0.0/1833.53.0.1 to 33.53.63.25433.53.63.25516,382
21433.53.64.0/1833.53.64.1 to 33.53.127.25433.53.127.25516,382
21533.53.128.0/1833.53.128.1 to 33.53.191.25433.53.191.25516,382
21633.53.192.0/1833.53.192.1 to 33.53.255.25433.53.255.25516,382
21733.54.0.0/1833.54.0.1 to 33.54.63.25433.54.63.25516,382
21833.54.64.0/1833.54.64.1 to 33.54.127.25433.54.127.25516,382
21933.54.128.0/1833.54.128.1 to 33.54.191.25433.54.191.25516,382
22033.54.192.0/1833.54.192.1 to 33.54.255.25433.54.255.25516,382
22133.55.0.0/1833.55.0.1 to 33.55.63.25433.55.63.25516,382
22233.55.64.0/1833.55.64.1 to 33.55.127.25433.55.127.25516,382
22333.55.128.0/1833.55.128.1 to 33.55.191.25433.55.191.25516,382
22433.55.192.0/1833.55.192.1 to 33.55.255.25433.55.255.25516,382
22533.56.0.0/1833.56.0.1 to 33.56.63.25433.56.63.25516,382
22633.56.64.0/1833.56.64.1 to 33.56.127.25433.56.127.25516,382
22733.56.128.0/1833.56.128.1 to 33.56.191.25433.56.191.25516,382
22833.56.192.0/1833.56.192.1 to 33.56.255.25433.56.255.25516,382
22933.57.0.0/1833.57.0.1 to 33.57.63.25433.57.63.25516,382
23033.57.64.0/1833.57.64.1 to 33.57.127.25433.57.127.25516,382
23133.57.128.0/1833.57.128.1 to 33.57.191.25433.57.191.25516,382
23233.57.192.0/1833.57.192.1 to 33.57.255.25433.57.255.25516,382
23333.58.0.0/1833.58.0.1 to 33.58.63.25433.58.63.25516,382
23433.58.64.0/1833.58.64.1 to 33.58.127.25433.58.127.25516,382
23533.58.128.0/1833.58.128.1 to 33.58.191.25433.58.191.25516,382
23633.58.192.0/1833.58.192.1 to 33.58.255.25433.58.255.25516,382
23733.59.0.0/1833.59.0.1 to 33.59.63.25433.59.63.25516,382
23833.59.64.0/1833.59.64.1 to 33.59.127.25433.59.127.25516,382
23933.59.128.0/1833.59.128.1 to 33.59.191.25433.59.191.25516,382
24033.59.192.0/1833.59.192.1 to 33.59.255.25433.59.255.25516,382
24133.60.0.0/1833.60.0.1 to 33.60.63.25433.60.63.25516,382
24233.60.64.0/1833.60.64.1 to 33.60.127.25433.60.127.25516,382
24333.60.128.0/1833.60.128.1 to 33.60.191.25433.60.191.25516,382
24433.60.192.0/1833.60.192.1 to 33.60.255.25433.60.255.25516,382
24533.61.0.0/1833.61.0.1 to 33.61.63.25433.61.63.25516,382
24633.61.64.0/1833.61.64.1 to 33.61.127.25433.61.127.25516,382
24733.61.128.0/1833.61.128.1 to 33.61.191.25433.61.191.25516,382
24833.61.192.0/1833.61.192.1 to 33.61.255.25433.61.255.25516,382
24933.62.0.0/1833.62.0.1 to 33.62.63.25433.62.63.25516,382
25033.62.64.0/1833.62.64.1 to 33.62.127.25433.62.127.25516,382
25133.62.128.0/1833.62.128.1 to 33.62.191.25433.62.191.25516,382
25233.62.192.0/1833.62.192.1 to 33.62.255.25433.62.255.25516,382
25333.63.0.0/1833.63.0.1 to 33.63.63.25433.63.63.25516,382
25433.63.64.0/1833.63.64.1 to 33.63.127.25433.63.127.25516,382
25533.63.128.0/1833.63.128.1 to 33.63.191.25433.63.191.25516,382
25633.63.192.0/1833.63.192.1 to 33.63.255.25433.63.255.25516,382

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.