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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.

Network18.237.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
18.237.0.0
Broadcast address
18.237.127.255
First usable
18.237.0.1
Last usable
18.237.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
A (default /8)
As numbers
Hex 12ED0000 · Integer 317521920 to 317554687
Reverse DNS zones
0.237.18.in-addr.arpa
1.237.18.in-addr.arpa
2.237.18.in-addr.arpa
3.237.18.in-addr.arpa
4.237.18.in-addr.arpa
5.237.18.in-addr.arpa
6.237.18.in-addr.arpa
7.237.18.in-addr.arpa
8.237.18.in-addr.arpa
9.237.18.in-addr.arpa
10.237.18.in-addr.arpa
11.237.18.in-addr.arpa
12.237.18.in-addr.arpa
13.237.18.in-addr.arpa
14.237.18.in-addr.arpa
15.237.18.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010010.11101101.00000000.0000000018.237.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network00010010.11101101.00000000.0000000018.237.0.0
Broadcast00010010.11101101.01111111.1111111118.237.127.255
Split into smaller subnets/26
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

18.237.0.0/17 makes 512 subnets of /26; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
118.237.0.0/2618.237.0.1 to 18.237.0.6218.237.0.6362
218.237.0.64/2618.237.0.65 to 18.237.0.12618.237.0.12762
318.237.0.128/2618.237.0.129 to 18.237.0.19018.237.0.19162
418.237.0.192/2618.237.0.193 to 18.237.0.25418.237.0.25562
518.237.1.0/2618.237.1.1 to 18.237.1.6218.237.1.6362
618.237.1.64/2618.237.1.65 to 18.237.1.12618.237.1.12762
718.237.1.128/2618.237.1.129 to 18.237.1.19018.237.1.19162
818.237.1.192/2618.237.1.193 to 18.237.1.25418.237.1.25562
918.237.2.0/2618.237.2.1 to 18.237.2.6218.237.2.6362
1018.237.2.64/2618.237.2.65 to 18.237.2.12618.237.2.12762
1118.237.2.128/2618.237.2.129 to 18.237.2.19018.237.2.19162
1218.237.2.192/2618.237.2.193 to 18.237.2.25418.237.2.25562
1318.237.3.0/2618.237.3.1 to 18.237.3.6218.237.3.6362
1418.237.3.64/2618.237.3.65 to 18.237.3.12618.237.3.12762
1518.237.3.128/2618.237.3.129 to 18.237.3.19018.237.3.19162
1618.237.3.192/2618.237.3.193 to 18.237.3.25418.237.3.25562
1718.237.4.0/2618.237.4.1 to 18.237.4.6218.237.4.6362
1818.237.4.64/2618.237.4.65 to 18.237.4.12618.237.4.12762
1918.237.4.128/2618.237.4.129 to 18.237.4.19018.237.4.19162
2018.237.4.192/2618.237.4.193 to 18.237.4.25418.237.4.25562
2118.237.5.0/2618.237.5.1 to 18.237.5.6218.237.5.6362
2218.237.5.64/2618.237.5.65 to 18.237.5.12618.237.5.12762
2318.237.5.128/2618.237.5.129 to 18.237.5.19018.237.5.19162
2418.237.5.192/2618.237.5.193 to 18.237.5.25418.237.5.25562
2518.237.6.0/2618.237.6.1 to 18.237.6.6218.237.6.6362
2618.237.6.64/2618.237.6.65 to 18.237.6.12618.237.6.12762
2718.237.6.128/2618.237.6.129 to 18.237.6.19018.237.6.19162
2818.237.6.192/2618.237.6.193 to 18.237.6.25418.237.6.25562
2918.237.7.0/2618.237.7.1 to 18.237.7.6218.237.7.6362
3018.237.7.64/2618.237.7.65 to 18.237.7.12618.237.7.12762
3118.237.7.128/2618.237.7.129 to 18.237.7.19018.237.7.19162
3218.237.7.192/2618.237.7.193 to 18.237.7.25418.237.7.25562
3318.237.8.0/2618.237.8.1 to 18.237.8.6218.237.8.6362
3418.237.8.64/2618.237.8.65 to 18.237.8.12618.237.8.12762
3518.237.8.128/2618.237.8.129 to 18.237.8.19018.237.8.19162
3618.237.8.192/2618.237.8.193 to 18.237.8.25418.237.8.25562
3718.237.9.0/2618.237.9.1 to 18.237.9.6218.237.9.6362
3818.237.9.64/2618.237.9.65 to 18.237.9.12618.237.9.12762
3918.237.9.128/2618.237.9.129 to 18.237.9.19018.237.9.19162
4018.237.9.192/2618.237.9.193 to 18.237.9.25418.237.9.25562
4118.237.10.0/2618.237.10.1 to 18.237.10.6218.237.10.6362
4218.237.10.64/2618.237.10.65 to 18.237.10.12618.237.10.12762
4318.237.10.128/2618.237.10.129 to 18.237.10.19018.237.10.19162
4418.237.10.192/2618.237.10.193 to 18.237.10.25418.237.10.25562
4518.237.11.0/2618.237.11.1 to 18.237.11.6218.237.11.6362
4618.237.11.64/2618.237.11.65 to 18.237.11.12618.237.11.12762
4718.237.11.128/2618.237.11.129 to 18.237.11.19018.237.11.19162
4818.237.11.192/2618.237.11.193 to 18.237.11.25418.237.11.25562
4918.237.12.0/2618.237.12.1 to 18.237.12.6218.237.12.6362
5018.237.12.64/2618.237.12.65 to 18.237.12.12618.237.12.12762
5118.237.12.128/2618.237.12.129 to 18.237.12.19018.237.12.19162
5218.237.12.192/2618.237.12.193 to 18.237.12.25418.237.12.25562
5318.237.13.0/2618.237.13.1 to 18.237.13.6218.237.13.6362
5418.237.13.64/2618.237.13.65 to 18.237.13.12618.237.13.12762
5518.237.13.128/2618.237.13.129 to 18.237.13.19018.237.13.19162
5618.237.13.192/2618.237.13.193 to 18.237.13.25418.237.13.25562
5718.237.14.0/2618.237.14.1 to 18.237.14.6218.237.14.6362
5818.237.14.64/2618.237.14.65 to 18.237.14.12618.237.14.12762
5918.237.14.128/2618.237.14.129 to 18.237.14.19018.237.14.19162
6018.237.14.192/2618.237.14.193 to 18.237.14.25418.237.14.25562
6118.237.15.0/2618.237.15.1 to 18.237.15.6218.237.15.6362
6218.237.15.64/2618.237.15.65 to 18.237.15.12618.237.15.12762
6318.237.15.128/2618.237.15.129 to 18.237.15.19018.237.15.19162
6418.237.15.192/2618.237.15.193 to 18.237.15.25418.237.15.25562
6518.237.16.0/2618.237.16.1 to 18.237.16.6218.237.16.6362
6618.237.16.64/2618.237.16.65 to 18.237.16.12618.237.16.12762
6718.237.16.128/2618.237.16.129 to 18.237.16.19018.237.16.19162
6818.237.16.192/2618.237.16.193 to 18.237.16.25418.237.16.25562
6918.237.17.0/2618.237.17.1 to 18.237.17.6218.237.17.6362
7018.237.17.64/2618.237.17.65 to 18.237.17.12618.237.17.12762
7118.237.17.128/2618.237.17.129 to 18.237.17.19018.237.17.19162
7218.237.17.192/2618.237.17.193 to 18.237.17.25418.237.17.25562
7318.237.18.0/2618.237.18.1 to 18.237.18.6218.237.18.6362
7418.237.18.64/2618.237.18.65 to 18.237.18.12618.237.18.12762
7518.237.18.128/2618.237.18.129 to 18.237.18.19018.237.18.19162
7618.237.18.192/2618.237.18.193 to 18.237.18.25418.237.18.25562
7718.237.19.0/2618.237.19.1 to 18.237.19.6218.237.19.6362
7818.237.19.64/2618.237.19.65 to 18.237.19.12618.237.19.12762
7918.237.19.128/2618.237.19.129 to 18.237.19.19018.237.19.19162
8018.237.19.192/2618.237.19.193 to 18.237.19.25418.237.19.25562
8118.237.20.0/2618.237.20.1 to 18.237.20.6218.237.20.6362
8218.237.20.64/2618.237.20.65 to 18.237.20.12618.237.20.12762
8318.237.20.128/2618.237.20.129 to 18.237.20.19018.237.20.19162
8418.237.20.192/2618.237.20.193 to 18.237.20.25418.237.20.25562
8518.237.21.0/2618.237.21.1 to 18.237.21.6218.237.21.6362
8618.237.21.64/2618.237.21.65 to 18.237.21.12618.237.21.12762
8718.237.21.128/2618.237.21.129 to 18.237.21.19018.237.21.19162
8818.237.21.192/2618.237.21.193 to 18.237.21.25418.237.21.25562
8918.237.22.0/2618.237.22.1 to 18.237.22.6218.237.22.6362
9018.237.22.64/2618.237.22.65 to 18.237.22.12618.237.22.12762
9118.237.22.128/2618.237.22.129 to 18.237.22.19018.237.22.19162
9218.237.22.192/2618.237.22.193 to 18.237.22.25418.237.22.25562
9318.237.23.0/2618.237.23.1 to 18.237.23.6218.237.23.6362
9418.237.23.64/2618.237.23.65 to 18.237.23.12618.237.23.12762
9518.237.23.128/2618.237.23.129 to 18.237.23.19018.237.23.19162
9618.237.23.192/2618.237.23.193 to 18.237.23.25418.237.23.25562
9718.237.24.0/2618.237.24.1 to 18.237.24.6218.237.24.6362
9818.237.24.64/2618.237.24.65 to 18.237.24.12618.237.24.12762
9918.237.24.128/2618.237.24.129 to 18.237.24.19018.237.24.19162
10018.237.24.192/2618.237.24.193 to 18.237.24.25418.237.24.25562
10118.237.25.0/2618.237.25.1 to 18.237.25.6218.237.25.6362
10218.237.25.64/2618.237.25.65 to 18.237.25.12618.237.25.12762
10318.237.25.128/2618.237.25.129 to 18.237.25.19018.237.25.19162
10418.237.25.192/2618.237.25.193 to 18.237.25.25418.237.25.25562
10518.237.26.0/2618.237.26.1 to 18.237.26.6218.237.26.6362
10618.237.26.64/2618.237.26.65 to 18.237.26.12618.237.26.12762
10718.237.26.128/2618.237.26.129 to 18.237.26.19018.237.26.19162
10818.237.26.192/2618.237.26.193 to 18.237.26.25418.237.26.25562
10918.237.27.0/2618.237.27.1 to 18.237.27.6218.237.27.6362
11018.237.27.64/2618.237.27.65 to 18.237.27.12618.237.27.12762
11118.237.27.128/2618.237.27.129 to 18.237.27.19018.237.27.19162
11218.237.27.192/2618.237.27.193 to 18.237.27.25418.237.27.25562
11318.237.28.0/2618.237.28.1 to 18.237.28.6218.237.28.6362
11418.237.28.64/2618.237.28.65 to 18.237.28.12618.237.28.12762
11518.237.28.128/2618.237.28.129 to 18.237.28.19018.237.28.19162
11618.237.28.192/2618.237.28.193 to 18.237.28.25418.237.28.25562
11718.237.29.0/2618.237.29.1 to 18.237.29.6218.237.29.6362
11818.237.29.64/2618.237.29.65 to 18.237.29.12618.237.29.12762
11918.237.29.128/2618.237.29.129 to 18.237.29.19018.237.29.19162
12018.237.29.192/2618.237.29.193 to 18.237.29.25418.237.29.25562
12118.237.30.0/2618.237.30.1 to 18.237.30.6218.237.30.6362
12218.237.30.64/2618.237.30.65 to 18.237.30.12618.237.30.12762
12318.237.30.128/2618.237.30.129 to 18.237.30.19018.237.30.19162
12418.237.30.192/2618.237.30.193 to 18.237.30.25418.237.30.25562
12518.237.31.0/2618.237.31.1 to 18.237.31.6218.237.31.6362
12618.237.31.64/2618.237.31.65 to 18.237.31.12618.237.31.12762
12718.237.31.128/2618.237.31.129 to 18.237.31.19018.237.31.19162
12818.237.31.192/2618.237.31.193 to 18.237.31.25418.237.31.25562
12918.237.32.0/2618.237.32.1 to 18.237.32.6218.237.32.6362
13018.237.32.64/2618.237.32.65 to 18.237.32.12618.237.32.12762
13118.237.32.128/2618.237.32.129 to 18.237.32.19018.237.32.19162
13218.237.32.192/2618.237.32.193 to 18.237.32.25418.237.32.25562
13318.237.33.0/2618.237.33.1 to 18.237.33.6218.237.33.6362
13418.237.33.64/2618.237.33.65 to 18.237.33.12618.237.33.12762
13518.237.33.128/2618.237.33.129 to 18.237.33.19018.237.33.19162
13618.237.33.192/2618.237.33.193 to 18.237.33.25418.237.33.25562
13718.237.34.0/2618.237.34.1 to 18.237.34.6218.237.34.6362
13818.237.34.64/2618.237.34.65 to 18.237.34.12618.237.34.12762
13918.237.34.128/2618.237.34.129 to 18.237.34.19018.237.34.19162
14018.237.34.192/2618.237.34.193 to 18.237.34.25418.237.34.25562
14118.237.35.0/2618.237.35.1 to 18.237.35.6218.237.35.6362
14218.237.35.64/2618.237.35.65 to 18.237.35.12618.237.35.12762
14318.237.35.128/2618.237.35.129 to 18.237.35.19018.237.35.19162
14418.237.35.192/2618.237.35.193 to 18.237.35.25418.237.35.25562
14518.237.36.0/2618.237.36.1 to 18.237.36.6218.237.36.6362
14618.237.36.64/2618.237.36.65 to 18.237.36.12618.237.36.12762
14718.237.36.128/2618.237.36.129 to 18.237.36.19018.237.36.19162
14818.237.36.192/2618.237.36.193 to 18.237.36.25418.237.36.25562
14918.237.37.0/2618.237.37.1 to 18.237.37.6218.237.37.6362
15018.237.37.64/2618.237.37.65 to 18.237.37.12618.237.37.12762
15118.237.37.128/2618.237.37.129 to 18.237.37.19018.237.37.19162
15218.237.37.192/2618.237.37.193 to 18.237.37.25418.237.37.25562
15318.237.38.0/2618.237.38.1 to 18.237.38.6218.237.38.6362
15418.237.38.64/2618.237.38.65 to 18.237.38.12618.237.38.12762
15518.237.38.128/2618.237.38.129 to 18.237.38.19018.237.38.19162
15618.237.38.192/2618.237.38.193 to 18.237.38.25418.237.38.25562
15718.237.39.0/2618.237.39.1 to 18.237.39.6218.237.39.6362
15818.237.39.64/2618.237.39.65 to 18.237.39.12618.237.39.12762
15918.237.39.128/2618.237.39.129 to 18.237.39.19018.237.39.19162
16018.237.39.192/2618.237.39.193 to 18.237.39.25418.237.39.25562
16118.237.40.0/2618.237.40.1 to 18.237.40.6218.237.40.6362
16218.237.40.64/2618.237.40.65 to 18.237.40.12618.237.40.12762
16318.237.40.128/2618.237.40.129 to 18.237.40.19018.237.40.19162
16418.237.40.192/2618.237.40.193 to 18.237.40.25418.237.40.25562
16518.237.41.0/2618.237.41.1 to 18.237.41.6218.237.41.6362
16618.237.41.64/2618.237.41.65 to 18.237.41.12618.237.41.12762
16718.237.41.128/2618.237.41.129 to 18.237.41.19018.237.41.19162
16818.237.41.192/2618.237.41.193 to 18.237.41.25418.237.41.25562
16918.237.42.0/2618.237.42.1 to 18.237.42.6218.237.42.6362
17018.237.42.64/2618.237.42.65 to 18.237.42.12618.237.42.12762
17118.237.42.128/2618.237.42.129 to 18.237.42.19018.237.42.19162
17218.237.42.192/2618.237.42.193 to 18.237.42.25418.237.42.25562
17318.237.43.0/2618.237.43.1 to 18.237.43.6218.237.43.6362
17418.237.43.64/2618.237.43.65 to 18.237.43.12618.237.43.12762
17518.237.43.128/2618.237.43.129 to 18.237.43.19018.237.43.19162
17618.237.43.192/2618.237.43.193 to 18.237.43.25418.237.43.25562
17718.237.44.0/2618.237.44.1 to 18.237.44.6218.237.44.6362
17818.237.44.64/2618.237.44.65 to 18.237.44.12618.237.44.12762
17918.237.44.128/2618.237.44.129 to 18.237.44.19018.237.44.19162
18018.237.44.192/2618.237.44.193 to 18.237.44.25418.237.44.25562
18118.237.45.0/2618.237.45.1 to 18.237.45.6218.237.45.6362
18218.237.45.64/2618.237.45.65 to 18.237.45.12618.237.45.12762
18318.237.45.128/2618.237.45.129 to 18.237.45.19018.237.45.19162
18418.237.45.192/2618.237.45.193 to 18.237.45.25418.237.45.25562
18518.237.46.0/2618.237.46.1 to 18.237.46.6218.237.46.6362
18618.237.46.64/2618.237.46.65 to 18.237.46.12618.237.46.12762
18718.237.46.128/2618.237.46.129 to 18.237.46.19018.237.46.19162
18818.237.46.192/2618.237.46.193 to 18.237.46.25418.237.46.25562
18918.237.47.0/2618.237.47.1 to 18.237.47.6218.237.47.6362
19018.237.47.64/2618.237.47.65 to 18.237.47.12618.237.47.12762
19118.237.47.128/2618.237.47.129 to 18.237.47.19018.237.47.19162
19218.237.47.192/2618.237.47.193 to 18.237.47.25418.237.47.25562
19318.237.48.0/2618.237.48.1 to 18.237.48.6218.237.48.6362
19418.237.48.64/2618.237.48.65 to 18.237.48.12618.237.48.12762
19518.237.48.128/2618.237.48.129 to 18.237.48.19018.237.48.19162
19618.237.48.192/2618.237.48.193 to 18.237.48.25418.237.48.25562
19718.237.49.0/2618.237.49.1 to 18.237.49.6218.237.49.6362
19818.237.49.64/2618.237.49.65 to 18.237.49.12618.237.49.12762
19918.237.49.128/2618.237.49.129 to 18.237.49.19018.237.49.19162
20018.237.49.192/2618.237.49.193 to 18.237.49.25418.237.49.25562
20118.237.50.0/2618.237.50.1 to 18.237.50.6218.237.50.6362
20218.237.50.64/2618.237.50.65 to 18.237.50.12618.237.50.12762
20318.237.50.128/2618.237.50.129 to 18.237.50.19018.237.50.19162
20418.237.50.192/2618.237.50.193 to 18.237.50.25418.237.50.25562
20518.237.51.0/2618.237.51.1 to 18.237.51.6218.237.51.6362
20618.237.51.64/2618.237.51.65 to 18.237.51.12618.237.51.12762
20718.237.51.128/2618.237.51.129 to 18.237.51.19018.237.51.19162
20818.237.51.192/2618.237.51.193 to 18.237.51.25418.237.51.25562
20918.237.52.0/2618.237.52.1 to 18.237.52.6218.237.52.6362
21018.237.52.64/2618.237.52.65 to 18.237.52.12618.237.52.12762
21118.237.52.128/2618.237.52.129 to 18.237.52.19018.237.52.19162
21218.237.52.192/2618.237.52.193 to 18.237.52.25418.237.52.25562
21318.237.53.0/2618.237.53.1 to 18.237.53.6218.237.53.6362
21418.237.53.64/2618.237.53.65 to 18.237.53.12618.237.53.12762
21518.237.53.128/2618.237.53.129 to 18.237.53.19018.237.53.19162
21618.237.53.192/2618.237.53.193 to 18.237.53.25418.237.53.25562
21718.237.54.0/2618.237.54.1 to 18.237.54.6218.237.54.6362
21818.237.54.64/2618.237.54.65 to 18.237.54.12618.237.54.12762
21918.237.54.128/2618.237.54.129 to 18.237.54.19018.237.54.19162
22018.237.54.192/2618.237.54.193 to 18.237.54.25418.237.54.25562
22118.237.55.0/2618.237.55.1 to 18.237.55.6218.237.55.6362
22218.237.55.64/2618.237.55.65 to 18.237.55.12618.237.55.12762
22318.237.55.128/2618.237.55.129 to 18.237.55.19018.237.55.19162
22418.237.55.192/2618.237.55.193 to 18.237.55.25418.237.55.25562
22518.237.56.0/2618.237.56.1 to 18.237.56.6218.237.56.6362
22618.237.56.64/2618.237.56.65 to 18.237.56.12618.237.56.12762
22718.237.56.128/2618.237.56.129 to 18.237.56.19018.237.56.19162
22818.237.56.192/2618.237.56.193 to 18.237.56.25418.237.56.25562
22918.237.57.0/2618.237.57.1 to 18.237.57.6218.237.57.6362
23018.237.57.64/2618.237.57.65 to 18.237.57.12618.237.57.12762
23118.237.57.128/2618.237.57.129 to 18.237.57.19018.237.57.19162
23218.237.57.192/2618.237.57.193 to 18.237.57.25418.237.57.25562
23318.237.58.0/2618.237.58.1 to 18.237.58.6218.237.58.6362
23418.237.58.64/2618.237.58.65 to 18.237.58.12618.237.58.12762
23518.237.58.128/2618.237.58.129 to 18.237.58.19018.237.58.19162
23618.237.58.192/2618.237.58.193 to 18.237.58.25418.237.58.25562
23718.237.59.0/2618.237.59.1 to 18.237.59.6218.237.59.6362
23818.237.59.64/2618.237.59.65 to 18.237.59.12618.237.59.12762
23918.237.59.128/2618.237.59.129 to 18.237.59.19018.237.59.19162
24018.237.59.192/2618.237.59.193 to 18.237.59.25418.237.59.25562
24118.237.60.0/2618.237.60.1 to 18.237.60.6218.237.60.6362
24218.237.60.64/2618.237.60.65 to 18.237.60.12618.237.60.12762
24318.237.60.128/2618.237.60.129 to 18.237.60.19018.237.60.19162
24418.237.60.192/2618.237.60.193 to 18.237.60.25418.237.60.25562
24518.237.61.0/2618.237.61.1 to 18.237.61.6218.237.61.6362
24618.237.61.64/2618.237.61.65 to 18.237.61.12618.237.61.12762
24718.237.61.128/2618.237.61.129 to 18.237.61.19018.237.61.19162
24818.237.61.192/2618.237.61.193 to 18.237.61.25418.237.61.25562
24918.237.62.0/2618.237.62.1 to 18.237.62.6218.237.62.6362
25018.237.62.64/2618.237.62.65 to 18.237.62.12618.237.62.12762
25118.237.62.128/2618.237.62.129 to 18.237.62.19018.237.62.19162
25218.237.62.192/2618.237.62.193 to 18.237.62.25418.237.62.25562
25318.237.63.0/2618.237.63.1 to 18.237.63.6218.237.63.6362
25418.237.63.64/2618.237.63.65 to 18.237.63.12618.237.63.12762
25518.237.63.128/2618.237.63.129 to 18.237.63.19018.237.63.19162
25618.237.63.192/2618.237.63.193 to 18.237.63.25418.237.63.25562

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.