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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.

Network31.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
31.0.0.0
Broadcast address
31.255.255.255
First usable
31.0.0.1
Last usable
31.255.255.254
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 1F000000 · Integer 520093696 to 536870911
Reverse DNS zone
31.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011111..00000000.00000000.0000000031.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00011111..00000000.00000000.0000000031.0.0.0
Broadcast00011111..11111111.11111111.1111111131.255.255.255
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)

31.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
131.0.0.0/1831.0.0.1 to 31.0.63.25431.0.63.25516,382
231.0.64.0/1831.0.64.1 to 31.0.127.25431.0.127.25516,382
331.0.128.0/1831.0.128.1 to 31.0.191.25431.0.191.25516,382
431.0.192.0/1831.0.192.1 to 31.0.255.25431.0.255.25516,382
531.1.0.0/1831.1.0.1 to 31.1.63.25431.1.63.25516,382
631.1.64.0/1831.1.64.1 to 31.1.127.25431.1.127.25516,382
731.1.128.0/1831.1.128.1 to 31.1.191.25431.1.191.25516,382
831.1.192.0/1831.1.192.1 to 31.1.255.25431.1.255.25516,382
931.2.0.0/1831.2.0.1 to 31.2.63.25431.2.63.25516,382
1031.2.64.0/1831.2.64.1 to 31.2.127.25431.2.127.25516,382
1131.2.128.0/1831.2.128.1 to 31.2.191.25431.2.191.25516,382
1231.2.192.0/1831.2.192.1 to 31.2.255.25431.2.255.25516,382
1331.3.0.0/1831.3.0.1 to 31.3.63.25431.3.63.25516,382
1431.3.64.0/1831.3.64.1 to 31.3.127.25431.3.127.25516,382
1531.3.128.0/1831.3.128.1 to 31.3.191.25431.3.191.25516,382
1631.3.192.0/1831.3.192.1 to 31.3.255.25431.3.255.25516,382
1731.4.0.0/1831.4.0.1 to 31.4.63.25431.4.63.25516,382
1831.4.64.0/1831.4.64.1 to 31.4.127.25431.4.127.25516,382
1931.4.128.0/1831.4.128.1 to 31.4.191.25431.4.191.25516,382
2031.4.192.0/1831.4.192.1 to 31.4.255.25431.4.255.25516,382
2131.5.0.0/1831.5.0.1 to 31.5.63.25431.5.63.25516,382
2231.5.64.0/1831.5.64.1 to 31.5.127.25431.5.127.25516,382
2331.5.128.0/1831.5.128.1 to 31.5.191.25431.5.191.25516,382
2431.5.192.0/1831.5.192.1 to 31.5.255.25431.5.255.25516,382
2531.6.0.0/1831.6.0.1 to 31.6.63.25431.6.63.25516,382
2631.6.64.0/1831.6.64.1 to 31.6.127.25431.6.127.25516,382
2731.6.128.0/1831.6.128.1 to 31.6.191.25431.6.191.25516,382
2831.6.192.0/1831.6.192.1 to 31.6.255.25431.6.255.25516,382
2931.7.0.0/1831.7.0.1 to 31.7.63.25431.7.63.25516,382
3031.7.64.0/1831.7.64.1 to 31.7.127.25431.7.127.25516,382
3131.7.128.0/1831.7.128.1 to 31.7.191.25431.7.191.25516,382
3231.7.192.0/1831.7.192.1 to 31.7.255.25431.7.255.25516,382
3331.8.0.0/1831.8.0.1 to 31.8.63.25431.8.63.25516,382
3431.8.64.0/1831.8.64.1 to 31.8.127.25431.8.127.25516,382
3531.8.128.0/1831.8.128.1 to 31.8.191.25431.8.191.25516,382
3631.8.192.0/1831.8.192.1 to 31.8.255.25431.8.255.25516,382
3731.9.0.0/1831.9.0.1 to 31.9.63.25431.9.63.25516,382
3831.9.64.0/1831.9.64.1 to 31.9.127.25431.9.127.25516,382
3931.9.128.0/1831.9.128.1 to 31.9.191.25431.9.191.25516,382
4031.9.192.0/1831.9.192.1 to 31.9.255.25431.9.255.25516,382
4131.10.0.0/1831.10.0.1 to 31.10.63.25431.10.63.25516,382
4231.10.64.0/1831.10.64.1 to 31.10.127.25431.10.127.25516,382
4331.10.128.0/1831.10.128.1 to 31.10.191.25431.10.191.25516,382
4431.10.192.0/1831.10.192.1 to 31.10.255.25431.10.255.25516,382
4531.11.0.0/1831.11.0.1 to 31.11.63.25431.11.63.25516,382
4631.11.64.0/1831.11.64.1 to 31.11.127.25431.11.127.25516,382
4731.11.128.0/1831.11.128.1 to 31.11.191.25431.11.191.25516,382
4831.11.192.0/1831.11.192.1 to 31.11.255.25431.11.255.25516,382
4931.12.0.0/1831.12.0.1 to 31.12.63.25431.12.63.25516,382
5031.12.64.0/1831.12.64.1 to 31.12.127.25431.12.127.25516,382
5131.12.128.0/1831.12.128.1 to 31.12.191.25431.12.191.25516,382
5231.12.192.0/1831.12.192.1 to 31.12.255.25431.12.255.25516,382
5331.13.0.0/1831.13.0.1 to 31.13.63.25431.13.63.25516,382
5431.13.64.0/1831.13.64.1 to 31.13.127.25431.13.127.25516,382
5531.13.128.0/1831.13.128.1 to 31.13.191.25431.13.191.25516,382
5631.13.192.0/1831.13.192.1 to 31.13.255.25431.13.255.25516,382
5731.14.0.0/1831.14.0.1 to 31.14.63.25431.14.63.25516,382
5831.14.64.0/1831.14.64.1 to 31.14.127.25431.14.127.25516,382
5931.14.128.0/1831.14.128.1 to 31.14.191.25431.14.191.25516,382
6031.14.192.0/1831.14.192.1 to 31.14.255.25431.14.255.25516,382
6131.15.0.0/1831.15.0.1 to 31.15.63.25431.15.63.25516,382
6231.15.64.0/1831.15.64.1 to 31.15.127.25431.15.127.25516,382
6331.15.128.0/1831.15.128.1 to 31.15.191.25431.15.191.25516,382
6431.15.192.0/1831.15.192.1 to 31.15.255.25431.15.255.25516,382
6531.16.0.0/1831.16.0.1 to 31.16.63.25431.16.63.25516,382
6631.16.64.0/1831.16.64.1 to 31.16.127.25431.16.127.25516,382
6731.16.128.0/1831.16.128.1 to 31.16.191.25431.16.191.25516,382
6831.16.192.0/1831.16.192.1 to 31.16.255.25431.16.255.25516,382
6931.17.0.0/1831.17.0.1 to 31.17.63.25431.17.63.25516,382
7031.17.64.0/1831.17.64.1 to 31.17.127.25431.17.127.25516,382
7131.17.128.0/1831.17.128.1 to 31.17.191.25431.17.191.25516,382
7231.17.192.0/1831.17.192.1 to 31.17.255.25431.17.255.25516,382
7331.18.0.0/1831.18.0.1 to 31.18.63.25431.18.63.25516,382
7431.18.64.0/1831.18.64.1 to 31.18.127.25431.18.127.25516,382
7531.18.128.0/1831.18.128.1 to 31.18.191.25431.18.191.25516,382
7631.18.192.0/1831.18.192.1 to 31.18.255.25431.18.255.25516,382
7731.19.0.0/1831.19.0.1 to 31.19.63.25431.19.63.25516,382
7831.19.64.0/1831.19.64.1 to 31.19.127.25431.19.127.25516,382
7931.19.128.0/1831.19.128.1 to 31.19.191.25431.19.191.25516,382
8031.19.192.0/1831.19.192.1 to 31.19.255.25431.19.255.25516,382
8131.20.0.0/1831.20.0.1 to 31.20.63.25431.20.63.25516,382
8231.20.64.0/1831.20.64.1 to 31.20.127.25431.20.127.25516,382
8331.20.128.0/1831.20.128.1 to 31.20.191.25431.20.191.25516,382
8431.20.192.0/1831.20.192.1 to 31.20.255.25431.20.255.25516,382
8531.21.0.0/1831.21.0.1 to 31.21.63.25431.21.63.25516,382
8631.21.64.0/1831.21.64.1 to 31.21.127.25431.21.127.25516,382
8731.21.128.0/1831.21.128.1 to 31.21.191.25431.21.191.25516,382
8831.21.192.0/1831.21.192.1 to 31.21.255.25431.21.255.25516,382
8931.22.0.0/1831.22.0.1 to 31.22.63.25431.22.63.25516,382
9031.22.64.0/1831.22.64.1 to 31.22.127.25431.22.127.25516,382
9131.22.128.0/1831.22.128.1 to 31.22.191.25431.22.191.25516,382
9231.22.192.0/1831.22.192.1 to 31.22.255.25431.22.255.25516,382
9331.23.0.0/1831.23.0.1 to 31.23.63.25431.23.63.25516,382
9431.23.64.0/1831.23.64.1 to 31.23.127.25431.23.127.25516,382
9531.23.128.0/1831.23.128.1 to 31.23.191.25431.23.191.25516,382
9631.23.192.0/1831.23.192.1 to 31.23.255.25431.23.255.25516,382
9731.24.0.0/1831.24.0.1 to 31.24.63.25431.24.63.25516,382
9831.24.64.0/1831.24.64.1 to 31.24.127.25431.24.127.25516,382
9931.24.128.0/1831.24.128.1 to 31.24.191.25431.24.191.25516,382
10031.24.192.0/1831.24.192.1 to 31.24.255.25431.24.255.25516,382
10131.25.0.0/1831.25.0.1 to 31.25.63.25431.25.63.25516,382
10231.25.64.0/1831.25.64.1 to 31.25.127.25431.25.127.25516,382
10331.25.128.0/1831.25.128.1 to 31.25.191.25431.25.191.25516,382
10431.25.192.0/1831.25.192.1 to 31.25.255.25431.25.255.25516,382
10531.26.0.0/1831.26.0.1 to 31.26.63.25431.26.63.25516,382
10631.26.64.0/1831.26.64.1 to 31.26.127.25431.26.127.25516,382
10731.26.128.0/1831.26.128.1 to 31.26.191.25431.26.191.25516,382
10831.26.192.0/1831.26.192.1 to 31.26.255.25431.26.255.25516,382
10931.27.0.0/1831.27.0.1 to 31.27.63.25431.27.63.25516,382
11031.27.64.0/1831.27.64.1 to 31.27.127.25431.27.127.25516,382
11131.27.128.0/1831.27.128.1 to 31.27.191.25431.27.191.25516,382
11231.27.192.0/1831.27.192.1 to 31.27.255.25431.27.255.25516,382
11331.28.0.0/1831.28.0.1 to 31.28.63.25431.28.63.25516,382
11431.28.64.0/1831.28.64.1 to 31.28.127.25431.28.127.25516,382
11531.28.128.0/1831.28.128.1 to 31.28.191.25431.28.191.25516,382
11631.28.192.0/1831.28.192.1 to 31.28.255.25431.28.255.25516,382
11731.29.0.0/1831.29.0.1 to 31.29.63.25431.29.63.25516,382
11831.29.64.0/1831.29.64.1 to 31.29.127.25431.29.127.25516,382
11931.29.128.0/1831.29.128.1 to 31.29.191.25431.29.191.25516,382
12031.29.192.0/1831.29.192.1 to 31.29.255.25431.29.255.25516,382
12131.30.0.0/1831.30.0.1 to 31.30.63.25431.30.63.25516,382
12231.30.64.0/1831.30.64.1 to 31.30.127.25431.30.127.25516,382
12331.30.128.0/1831.30.128.1 to 31.30.191.25431.30.191.25516,382
12431.30.192.0/1831.30.192.1 to 31.30.255.25431.30.255.25516,382
12531.31.0.0/1831.31.0.1 to 31.31.63.25431.31.63.25516,382
12631.31.64.0/1831.31.64.1 to 31.31.127.25431.31.127.25516,382
12731.31.128.0/1831.31.128.1 to 31.31.191.25431.31.191.25516,382
12831.31.192.0/1831.31.192.1 to 31.31.255.25431.31.255.25516,382
12931.32.0.0/1831.32.0.1 to 31.32.63.25431.32.63.25516,382
13031.32.64.0/1831.32.64.1 to 31.32.127.25431.32.127.25516,382
13131.32.128.0/1831.32.128.1 to 31.32.191.25431.32.191.25516,382
13231.32.192.0/1831.32.192.1 to 31.32.255.25431.32.255.25516,382
13331.33.0.0/1831.33.0.1 to 31.33.63.25431.33.63.25516,382
13431.33.64.0/1831.33.64.1 to 31.33.127.25431.33.127.25516,382
13531.33.128.0/1831.33.128.1 to 31.33.191.25431.33.191.25516,382
13631.33.192.0/1831.33.192.1 to 31.33.255.25431.33.255.25516,382
13731.34.0.0/1831.34.0.1 to 31.34.63.25431.34.63.25516,382
13831.34.64.0/1831.34.64.1 to 31.34.127.25431.34.127.25516,382
13931.34.128.0/1831.34.128.1 to 31.34.191.25431.34.191.25516,382
14031.34.192.0/1831.34.192.1 to 31.34.255.25431.34.255.25516,382
14131.35.0.0/1831.35.0.1 to 31.35.63.25431.35.63.25516,382
14231.35.64.0/1831.35.64.1 to 31.35.127.25431.35.127.25516,382
14331.35.128.0/1831.35.128.1 to 31.35.191.25431.35.191.25516,382
14431.35.192.0/1831.35.192.1 to 31.35.255.25431.35.255.25516,382
14531.36.0.0/1831.36.0.1 to 31.36.63.25431.36.63.25516,382
14631.36.64.0/1831.36.64.1 to 31.36.127.25431.36.127.25516,382
14731.36.128.0/1831.36.128.1 to 31.36.191.25431.36.191.25516,382
14831.36.192.0/1831.36.192.1 to 31.36.255.25431.36.255.25516,382
14931.37.0.0/1831.37.0.1 to 31.37.63.25431.37.63.25516,382
15031.37.64.0/1831.37.64.1 to 31.37.127.25431.37.127.25516,382
15131.37.128.0/1831.37.128.1 to 31.37.191.25431.37.191.25516,382
15231.37.192.0/1831.37.192.1 to 31.37.255.25431.37.255.25516,382
15331.38.0.0/1831.38.0.1 to 31.38.63.25431.38.63.25516,382
15431.38.64.0/1831.38.64.1 to 31.38.127.25431.38.127.25516,382
15531.38.128.0/1831.38.128.1 to 31.38.191.25431.38.191.25516,382
15631.38.192.0/1831.38.192.1 to 31.38.255.25431.38.255.25516,382
15731.39.0.0/1831.39.0.1 to 31.39.63.25431.39.63.25516,382
15831.39.64.0/1831.39.64.1 to 31.39.127.25431.39.127.25516,382
15931.39.128.0/1831.39.128.1 to 31.39.191.25431.39.191.25516,382
16031.39.192.0/1831.39.192.1 to 31.39.255.25431.39.255.25516,382
16131.40.0.0/1831.40.0.1 to 31.40.63.25431.40.63.25516,382
16231.40.64.0/1831.40.64.1 to 31.40.127.25431.40.127.25516,382
16331.40.128.0/1831.40.128.1 to 31.40.191.25431.40.191.25516,382
16431.40.192.0/1831.40.192.1 to 31.40.255.25431.40.255.25516,382
16531.41.0.0/1831.41.0.1 to 31.41.63.25431.41.63.25516,382
16631.41.64.0/1831.41.64.1 to 31.41.127.25431.41.127.25516,382
16731.41.128.0/1831.41.128.1 to 31.41.191.25431.41.191.25516,382
16831.41.192.0/1831.41.192.1 to 31.41.255.25431.41.255.25516,382
16931.42.0.0/1831.42.0.1 to 31.42.63.25431.42.63.25516,382
17031.42.64.0/1831.42.64.1 to 31.42.127.25431.42.127.25516,382
17131.42.128.0/1831.42.128.1 to 31.42.191.25431.42.191.25516,382
17231.42.192.0/1831.42.192.1 to 31.42.255.25431.42.255.25516,382
17331.43.0.0/1831.43.0.1 to 31.43.63.25431.43.63.25516,382
17431.43.64.0/1831.43.64.1 to 31.43.127.25431.43.127.25516,382
17531.43.128.0/1831.43.128.1 to 31.43.191.25431.43.191.25516,382
17631.43.192.0/1831.43.192.1 to 31.43.255.25431.43.255.25516,382
17731.44.0.0/1831.44.0.1 to 31.44.63.25431.44.63.25516,382
17831.44.64.0/1831.44.64.1 to 31.44.127.25431.44.127.25516,382
17931.44.128.0/1831.44.128.1 to 31.44.191.25431.44.191.25516,382
18031.44.192.0/1831.44.192.1 to 31.44.255.25431.44.255.25516,382
18131.45.0.0/1831.45.0.1 to 31.45.63.25431.45.63.25516,382
18231.45.64.0/1831.45.64.1 to 31.45.127.25431.45.127.25516,382
18331.45.128.0/1831.45.128.1 to 31.45.191.25431.45.191.25516,382
18431.45.192.0/1831.45.192.1 to 31.45.255.25431.45.255.25516,382
18531.46.0.0/1831.46.0.1 to 31.46.63.25431.46.63.25516,382
18631.46.64.0/1831.46.64.1 to 31.46.127.25431.46.127.25516,382
18731.46.128.0/1831.46.128.1 to 31.46.191.25431.46.191.25516,382
18831.46.192.0/1831.46.192.1 to 31.46.255.25431.46.255.25516,382
18931.47.0.0/1831.47.0.1 to 31.47.63.25431.47.63.25516,382
19031.47.64.0/1831.47.64.1 to 31.47.127.25431.47.127.25516,382
19131.47.128.0/1831.47.128.1 to 31.47.191.25431.47.191.25516,382
19231.47.192.0/1831.47.192.1 to 31.47.255.25431.47.255.25516,382
19331.48.0.0/1831.48.0.1 to 31.48.63.25431.48.63.25516,382
19431.48.64.0/1831.48.64.1 to 31.48.127.25431.48.127.25516,382
19531.48.128.0/1831.48.128.1 to 31.48.191.25431.48.191.25516,382
19631.48.192.0/1831.48.192.1 to 31.48.255.25431.48.255.25516,382
19731.49.0.0/1831.49.0.1 to 31.49.63.25431.49.63.25516,382
19831.49.64.0/1831.49.64.1 to 31.49.127.25431.49.127.25516,382
19931.49.128.0/1831.49.128.1 to 31.49.191.25431.49.191.25516,382
20031.49.192.0/1831.49.192.1 to 31.49.255.25431.49.255.25516,382
20131.50.0.0/1831.50.0.1 to 31.50.63.25431.50.63.25516,382
20231.50.64.0/1831.50.64.1 to 31.50.127.25431.50.127.25516,382
20331.50.128.0/1831.50.128.1 to 31.50.191.25431.50.191.25516,382
20431.50.192.0/1831.50.192.1 to 31.50.255.25431.50.255.25516,382
20531.51.0.0/1831.51.0.1 to 31.51.63.25431.51.63.25516,382
20631.51.64.0/1831.51.64.1 to 31.51.127.25431.51.127.25516,382
20731.51.128.0/1831.51.128.1 to 31.51.191.25431.51.191.25516,382
20831.51.192.0/1831.51.192.1 to 31.51.255.25431.51.255.25516,382
20931.52.0.0/1831.52.0.1 to 31.52.63.25431.52.63.25516,382
21031.52.64.0/1831.52.64.1 to 31.52.127.25431.52.127.25516,382
21131.52.128.0/1831.52.128.1 to 31.52.191.25431.52.191.25516,382
21231.52.192.0/1831.52.192.1 to 31.52.255.25431.52.255.25516,382
21331.53.0.0/1831.53.0.1 to 31.53.63.25431.53.63.25516,382
21431.53.64.0/1831.53.64.1 to 31.53.127.25431.53.127.25516,382
21531.53.128.0/1831.53.128.1 to 31.53.191.25431.53.191.25516,382
21631.53.192.0/1831.53.192.1 to 31.53.255.25431.53.255.25516,382
21731.54.0.0/1831.54.0.1 to 31.54.63.25431.54.63.25516,382
21831.54.64.0/1831.54.64.1 to 31.54.127.25431.54.127.25516,382
21931.54.128.0/1831.54.128.1 to 31.54.191.25431.54.191.25516,382
22031.54.192.0/1831.54.192.1 to 31.54.255.25431.54.255.25516,382
22131.55.0.0/1831.55.0.1 to 31.55.63.25431.55.63.25516,382
22231.55.64.0/1831.55.64.1 to 31.55.127.25431.55.127.25516,382
22331.55.128.0/1831.55.128.1 to 31.55.191.25431.55.191.25516,382
22431.55.192.0/1831.55.192.1 to 31.55.255.25431.55.255.25516,382
22531.56.0.0/1831.56.0.1 to 31.56.63.25431.56.63.25516,382
22631.56.64.0/1831.56.64.1 to 31.56.127.25431.56.127.25516,382
22731.56.128.0/1831.56.128.1 to 31.56.191.25431.56.191.25516,382
22831.56.192.0/1831.56.192.1 to 31.56.255.25431.56.255.25516,382
22931.57.0.0/1831.57.0.1 to 31.57.63.25431.57.63.25516,382
23031.57.64.0/1831.57.64.1 to 31.57.127.25431.57.127.25516,382
23131.57.128.0/1831.57.128.1 to 31.57.191.25431.57.191.25516,382
23231.57.192.0/1831.57.192.1 to 31.57.255.25431.57.255.25516,382
23331.58.0.0/1831.58.0.1 to 31.58.63.25431.58.63.25516,382
23431.58.64.0/1831.58.64.1 to 31.58.127.25431.58.127.25516,382
23531.58.128.0/1831.58.128.1 to 31.58.191.25431.58.191.25516,382
23631.58.192.0/1831.58.192.1 to 31.58.255.25431.58.255.25516,382
23731.59.0.0/1831.59.0.1 to 31.59.63.25431.59.63.25516,382
23831.59.64.0/1831.59.64.1 to 31.59.127.25431.59.127.25516,382
23931.59.128.0/1831.59.128.1 to 31.59.191.25431.59.191.25516,382
24031.59.192.0/1831.59.192.1 to 31.59.255.25431.59.255.25516,382
24131.60.0.0/1831.60.0.1 to 31.60.63.25431.60.63.25516,382
24231.60.64.0/1831.60.64.1 to 31.60.127.25431.60.127.25516,382
24331.60.128.0/1831.60.128.1 to 31.60.191.25431.60.191.25516,382
24431.60.192.0/1831.60.192.1 to 31.60.255.25431.60.255.25516,382
24531.61.0.0/1831.61.0.1 to 31.61.63.25431.61.63.25516,382
24631.61.64.0/1831.61.64.1 to 31.61.127.25431.61.127.25516,382
24731.61.128.0/1831.61.128.1 to 31.61.191.25431.61.191.25516,382
24831.61.192.0/1831.61.192.1 to 31.61.255.25431.61.255.25516,382
24931.62.0.0/1831.62.0.1 to 31.62.63.25431.62.63.25516,382
25031.62.64.0/1831.62.64.1 to 31.62.127.25431.62.127.25516,382
25131.62.128.0/1831.62.128.1 to 31.62.191.25431.62.191.25516,382
25231.62.192.0/1831.62.192.1 to 31.62.255.25431.62.255.25516,382
25331.63.0.0/1831.63.0.1 to 31.63.63.25431.63.63.25516,382
25431.63.64.0/1831.63.64.1 to 31.63.127.25431.63.127.25516,382
25531.63.128.0/1831.63.128.1 to 31.63.191.25431.63.191.25516,382
25631.63.192.0/1831.63.192.1 to 31.63.255.25431.63.255.25516,382

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.