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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.

Network31.64.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
31.64.0.0
Broadcast address
31.95.255.255
First usable
31.64.0.1
Last usable
31.95.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 1F400000 · Integer 524288000 to 526385151
Reverse DNS zones
64.31.in-addr.arpa
65.31.in-addr.arpa
66.31.in-addr.arpa
67.31.in-addr.arpa
68.31.in-addr.arpa
69.31.in-addr.arpa
70.31.in-addr.arpa
71.31.in-addr.arpa
72.31.in-addr.arpa
73.31.in-addr.arpa
74.31.in-addr.arpa
75.31.in-addr.arpa
76.31.in-addr.arpa
77.31.in-addr.arpa
78.31.in-addr.arpa
79.31.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011111.01000000.00000000.0000000031.64.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00011111.01000000.00000000.0000000031.64.0.0
Broadcast00011111.01011111.11111111.1111111131.95.255.255
Split into smaller subnets/21
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

31.64.0.0/11 makes 1,024 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
131.64.0.0/2131.64.0.1 to 31.64.7.25431.64.7.2552,046
231.64.8.0/2131.64.8.1 to 31.64.15.25431.64.15.2552,046
331.64.16.0/2131.64.16.1 to 31.64.23.25431.64.23.2552,046
431.64.24.0/2131.64.24.1 to 31.64.31.25431.64.31.2552,046
531.64.32.0/2131.64.32.1 to 31.64.39.25431.64.39.2552,046
631.64.40.0/2131.64.40.1 to 31.64.47.25431.64.47.2552,046
731.64.48.0/2131.64.48.1 to 31.64.55.25431.64.55.2552,046
831.64.56.0/2131.64.56.1 to 31.64.63.25431.64.63.2552,046
931.64.64.0/2131.64.64.1 to 31.64.71.25431.64.71.2552,046
1031.64.72.0/2131.64.72.1 to 31.64.79.25431.64.79.2552,046
1131.64.80.0/2131.64.80.1 to 31.64.87.25431.64.87.2552,046
1231.64.88.0/2131.64.88.1 to 31.64.95.25431.64.95.2552,046
1331.64.96.0/2131.64.96.1 to 31.64.103.25431.64.103.2552,046
1431.64.104.0/2131.64.104.1 to 31.64.111.25431.64.111.2552,046
1531.64.112.0/2131.64.112.1 to 31.64.119.25431.64.119.2552,046
1631.64.120.0/2131.64.120.1 to 31.64.127.25431.64.127.2552,046
1731.64.128.0/2131.64.128.1 to 31.64.135.25431.64.135.2552,046
1831.64.136.0/2131.64.136.1 to 31.64.143.25431.64.143.2552,046
1931.64.144.0/2131.64.144.1 to 31.64.151.25431.64.151.2552,046
2031.64.152.0/2131.64.152.1 to 31.64.159.25431.64.159.2552,046
2131.64.160.0/2131.64.160.1 to 31.64.167.25431.64.167.2552,046
2231.64.168.0/2131.64.168.1 to 31.64.175.25431.64.175.2552,046
2331.64.176.0/2131.64.176.1 to 31.64.183.25431.64.183.2552,046
2431.64.184.0/2131.64.184.1 to 31.64.191.25431.64.191.2552,046
2531.64.192.0/2131.64.192.1 to 31.64.199.25431.64.199.2552,046
2631.64.200.0/2131.64.200.1 to 31.64.207.25431.64.207.2552,046
2731.64.208.0/2131.64.208.1 to 31.64.215.25431.64.215.2552,046
2831.64.216.0/2131.64.216.1 to 31.64.223.25431.64.223.2552,046
2931.64.224.0/2131.64.224.1 to 31.64.231.25431.64.231.2552,046
3031.64.232.0/2131.64.232.1 to 31.64.239.25431.64.239.2552,046
3131.64.240.0/2131.64.240.1 to 31.64.247.25431.64.247.2552,046
3231.64.248.0/2131.64.248.1 to 31.64.255.25431.64.255.2552,046
3331.65.0.0/2131.65.0.1 to 31.65.7.25431.65.7.2552,046
3431.65.8.0/2131.65.8.1 to 31.65.15.25431.65.15.2552,046
3531.65.16.0/2131.65.16.1 to 31.65.23.25431.65.23.2552,046
3631.65.24.0/2131.65.24.1 to 31.65.31.25431.65.31.2552,046
3731.65.32.0/2131.65.32.1 to 31.65.39.25431.65.39.2552,046
3831.65.40.0/2131.65.40.1 to 31.65.47.25431.65.47.2552,046
3931.65.48.0/2131.65.48.1 to 31.65.55.25431.65.55.2552,046
4031.65.56.0/2131.65.56.1 to 31.65.63.25431.65.63.2552,046
4131.65.64.0/2131.65.64.1 to 31.65.71.25431.65.71.2552,046
4231.65.72.0/2131.65.72.1 to 31.65.79.25431.65.79.2552,046
4331.65.80.0/2131.65.80.1 to 31.65.87.25431.65.87.2552,046
4431.65.88.0/2131.65.88.1 to 31.65.95.25431.65.95.2552,046
4531.65.96.0/2131.65.96.1 to 31.65.103.25431.65.103.2552,046
4631.65.104.0/2131.65.104.1 to 31.65.111.25431.65.111.2552,046
4731.65.112.0/2131.65.112.1 to 31.65.119.25431.65.119.2552,046
4831.65.120.0/2131.65.120.1 to 31.65.127.25431.65.127.2552,046
4931.65.128.0/2131.65.128.1 to 31.65.135.25431.65.135.2552,046
5031.65.136.0/2131.65.136.1 to 31.65.143.25431.65.143.2552,046
5131.65.144.0/2131.65.144.1 to 31.65.151.25431.65.151.2552,046
5231.65.152.0/2131.65.152.1 to 31.65.159.25431.65.159.2552,046
5331.65.160.0/2131.65.160.1 to 31.65.167.25431.65.167.2552,046
5431.65.168.0/2131.65.168.1 to 31.65.175.25431.65.175.2552,046
5531.65.176.0/2131.65.176.1 to 31.65.183.25431.65.183.2552,046
5631.65.184.0/2131.65.184.1 to 31.65.191.25431.65.191.2552,046
5731.65.192.0/2131.65.192.1 to 31.65.199.25431.65.199.2552,046
5831.65.200.0/2131.65.200.1 to 31.65.207.25431.65.207.2552,046
5931.65.208.0/2131.65.208.1 to 31.65.215.25431.65.215.2552,046
6031.65.216.0/2131.65.216.1 to 31.65.223.25431.65.223.2552,046
6131.65.224.0/2131.65.224.1 to 31.65.231.25431.65.231.2552,046
6231.65.232.0/2131.65.232.1 to 31.65.239.25431.65.239.2552,046
6331.65.240.0/2131.65.240.1 to 31.65.247.25431.65.247.2552,046
6431.65.248.0/2131.65.248.1 to 31.65.255.25431.65.255.2552,046
6531.66.0.0/2131.66.0.1 to 31.66.7.25431.66.7.2552,046
6631.66.8.0/2131.66.8.1 to 31.66.15.25431.66.15.2552,046
6731.66.16.0/2131.66.16.1 to 31.66.23.25431.66.23.2552,046
6831.66.24.0/2131.66.24.1 to 31.66.31.25431.66.31.2552,046
6931.66.32.0/2131.66.32.1 to 31.66.39.25431.66.39.2552,046
7031.66.40.0/2131.66.40.1 to 31.66.47.25431.66.47.2552,046
7131.66.48.0/2131.66.48.1 to 31.66.55.25431.66.55.2552,046
7231.66.56.0/2131.66.56.1 to 31.66.63.25431.66.63.2552,046
7331.66.64.0/2131.66.64.1 to 31.66.71.25431.66.71.2552,046
7431.66.72.0/2131.66.72.1 to 31.66.79.25431.66.79.2552,046
7531.66.80.0/2131.66.80.1 to 31.66.87.25431.66.87.2552,046
7631.66.88.0/2131.66.88.1 to 31.66.95.25431.66.95.2552,046
7731.66.96.0/2131.66.96.1 to 31.66.103.25431.66.103.2552,046
7831.66.104.0/2131.66.104.1 to 31.66.111.25431.66.111.2552,046
7931.66.112.0/2131.66.112.1 to 31.66.119.25431.66.119.2552,046
8031.66.120.0/2131.66.120.1 to 31.66.127.25431.66.127.2552,046
8131.66.128.0/2131.66.128.1 to 31.66.135.25431.66.135.2552,046
8231.66.136.0/2131.66.136.1 to 31.66.143.25431.66.143.2552,046
8331.66.144.0/2131.66.144.1 to 31.66.151.25431.66.151.2552,046
8431.66.152.0/2131.66.152.1 to 31.66.159.25431.66.159.2552,046
8531.66.160.0/2131.66.160.1 to 31.66.167.25431.66.167.2552,046
8631.66.168.0/2131.66.168.1 to 31.66.175.25431.66.175.2552,046
8731.66.176.0/2131.66.176.1 to 31.66.183.25431.66.183.2552,046
8831.66.184.0/2131.66.184.1 to 31.66.191.25431.66.191.2552,046
8931.66.192.0/2131.66.192.1 to 31.66.199.25431.66.199.2552,046
9031.66.200.0/2131.66.200.1 to 31.66.207.25431.66.207.2552,046
9131.66.208.0/2131.66.208.1 to 31.66.215.25431.66.215.2552,046
9231.66.216.0/2131.66.216.1 to 31.66.223.25431.66.223.2552,046
9331.66.224.0/2131.66.224.1 to 31.66.231.25431.66.231.2552,046
9431.66.232.0/2131.66.232.1 to 31.66.239.25431.66.239.2552,046
9531.66.240.0/2131.66.240.1 to 31.66.247.25431.66.247.2552,046
9631.66.248.0/2131.66.248.1 to 31.66.255.25431.66.255.2552,046
9731.67.0.0/2131.67.0.1 to 31.67.7.25431.67.7.2552,046
9831.67.8.0/2131.67.8.1 to 31.67.15.25431.67.15.2552,046
9931.67.16.0/2131.67.16.1 to 31.67.23.25431.67.23.2552,046
10031.67.24.0/2131.67.24.1 to 31.67.31.25431.67.31.2552,046
10131.67.32.0/2131.67.32.1 to 31.67.39.25431.67.39.2552,046
10231.67.40.0/2131.67.40.1 to 31.67.47.25431.67.47.2552,046
10331.67.48.0/2131.67.48.1 to 31.67.55.25431.67.55.2552,046
10431.67.56.0/2131.67.56.1 to 31.67.63.25431.67.63.2552,046
10531.67.64.0/2131.67.64.1 to 31.67.71.25431.67.71.2552,046
10631.67.72.0/2131.67.72.1 to 31.67.79.25431.67.79.2552,046
10731.67.80.0/2131.67.80.1 to 31.67.87.25431.67.87.2552,046
10831.67.88.0/2131.67.88.1 to 31.67.95.25431.67.95.2552,046
10931.67.96.0/2131.67.96.1 to 31.67.103.25431.67.103.2552,046
11031.67.104.0/2131.67.104.1 to 31.67.111.25431.67.111.2552,046
11131.67.112.0/2131.67.112.1 to 31.67.119.25431.67.119.2552,046
11231.67.120.0/2131.67.120.1 to 31.67.127.25431.67.127.2552,046
11331.67.128.0/2131.67.128.1 to 31.67.135.25431.67.135.2552,046
11431.67.136.0/2131.67.136.1 to 31.67.143.25431.67.143.2552,046
11531.67.144.0/2131.67.144.1 to 31.67.151.25431.67.151.2552,046
11631.67.152.0/2131.67.152.1 to 31.67.159.25431.67.159.2552,046
11731.67.160.0/2131.67.160.1 to 31.67.167.25431.67.167.2552,046
11831.67.168.0/2131.67.168.1 to 31.67.175.25431.67.175.2552,046
11931.67.176.0/2131.67.176.1 to 31.67.183.25431.67.183.2552,046
12031.67.184.0/2131.67.184.1 to 31.67.191.25431.67.191.2552,046
12131.67.192.0/2131.67.192.1 to 31.67.199.25431.67.199.2552,046
12231.67.200.0/2131.67.200.1 to 31.67.207.25431.67.207.2552,046
12331.67.208.0/2131.67.208.1 to 31.67.215.25431.67.215.2552,046
12431.67.216.0/2131.67.216.1 to 31.67.223.25431.67.223.2552,046
12531.67.224.0/2131.67.224.1 to 31.67.231.25431.67.231.2552,046
12631.67.232.0/2131.67.232.1 to 31.67.239.25431.67.239.2552,046
12731.67.240.0/2131.67.240.1 to 31.67.247.25431.67.247.2552,046
12831.67.248.0/2131.67.248.1 to 31.67.255.25431.67.255.2552,046
12931.68.0.0/2131.68.0.1 to 31.68.7.25431.68.7.2552,046
13031.68.8.0/2131.68.8.1 to 31.68.15.25431.68.15.2552,046
13131.68.16.0/2131.68.16.1 to 31.68.23.25431.68.23.2552,046
13231.68.24.0/2131.68.24.1 to 31.68.31.25431.68.31.2552,046
13331.68.32.0/2131.68.32.1 to 31.68.39.25431.68.39.2552,046
13431.68.40.0/2131.68.40.1 to 31.68.47.25431.68.47.2552,046
13531.68.48.0/2131.68.48.1 to 31.68.55.25431.68.55.2552,046
13631.68.56.0/2131.68.56.1 to 31.68.63.25431.68.63.2552,046
13731.68.64.0/2131.68.64.1 to 31.68.71.25431.68.71.2552,046
13831.68.72.0/2131.68.72.1 to 31.68.79.25431.68.79.2552,046
13931.68.80.0/2131.68.80.1 to 31.68.87.25431.68.87.2552,046
14031.68.88.0/2131.68.88.1 to 31.68.95.25431.68.95.2552,046
14131.68.96.0/2131.68.96.1 to 31.68.103.25431.68.103.2552,046
14231.68.104.0/2131.68.104.1 to 31.68.111.25431.68.111.2552,046
14331.68.112.0/2131.68.112.1 to 31.68.119.25431.68.119.2552,046
14431.68.120.0/2131.68.120.1 to 31.68.127.25431.68.127.2552,046
14531.68.128.0/2131.68.128.1 to 31.68.135.25431.68.135.2552,046
14631.68.136.0/2131.68.136.1 to 31.68.143.25431.68.143.2552,046
14731.68.144.0/2131.68.144.1 to 31.68.151.25431.68.151.2552,046
14831.68.152.0/2131.68.152.1 to 31.68.159.25431.68.159.2552,046
14931.68.160.0/2131.68.160.1 to 31.68.167.25431.68.167.2552,046
15031.68.168.0/2131.68.168.1 to 31.68.175.25431.68.175.2552,046
15131.68.176.0/2131.68.176.1 to 31.68.183.25431.68.183.2552,046
15231.68.184.0/2131.68.184.1 to 31.68.191.25431.68.191.2552,046
15331.68.192.0/2131.68.192.1 to 31.68.199.25431.68.199.2552,046
15431.68.200.0/2131.68.200.1 to 31.68.207.25431.68.207.2552,046
15531.68.208.0/2131.68.208.1 to 31.68.215.25431.68.215.2552,046
15631.68.216.0/2131.68.216.1 to 31.68.223.25431.68.223.2552,046
15731.68.224.0/2131.68.224.1 to 31.68.231.25431.68.231.2552,046
15831.68.232.0/2131.68.232.1 to 31.68.239.25431.68.239.2552,046
15931.68.240.0/2131.68.240.1 to 31.68.247.25431.68.247.2552,046
16031.68.248.0/2131.68.248.1 to 31.68.255.25431.68.255.2552,046
16131.69.0.0/2131.69.0.1 to 31.69.7.25431.69.7.2552,046
16231.69.8.0/2131.69.8.1 to 31.69.15.25431.69.15.2552,046
16331.69.16.0/2131.69.16.1 to 31.69.23.25431.69.23.2552,046
16431.69.24.0/2131.69.24.1 to 31.69.31.25431.69.31.2552,046
16531.69.32.0/2131.69.32.1 to 31.69.39.25431.69.39.2552,046
16631.69.40.0/2131.69.40.1 to 31.69.47.25431.69.47.2552,046
16731.69.48.0/2131.69.48.1 to 31.69.55.25431.69.55.2552,046
16831.69.56.0/2131.69.56.1 to 31.69.63.25431.69.63.2552,046
16931.69.64.0/2131.69.64.1 to 31.69.71.25431.69.71.2552,046
17031.69.72.0/2131.69.72.1 to 31.69.79.25431.69.79.2552,046
17131.69.80.0/2131.69.80.1 to 31.69.87.25431.69.87.2552,046
17231.69.88.0/2131.69.88.1 to 31.69.95.25431.69.95.2552,046
17331.69.96.0/2131.69.96.1 to 31.69.103.25431.69.103.2552,046
17431.69.104.0/2131.69.104.1 to 31.69.111.25431.69.111.2552,046
17531.69.112.0/2131.69.112.1 to 31.69.119.25431.69.119.2552,046
17631.69.120.0/2131.69.120.1 to 31.69.127.25431.69.127.2552,046
17731.69.128.0/2131.69.128.1 to 31.69.135.25431.69.135.2552,046
17831.69.136.0/2131.69.136.1 to 31.69.143.25431.69.143.2552,046
17931.69.144.0/2131.69.144.1 to 31.69.151.25431.69.151.2552,046
18031.69.152.0/2131.69.152.1 to 31.69.159.25431.69.159.2552,046
18131.69.160.0/2131.69.160.1 to 31.69.167.25431.69.167.2552,046
18231.69.168.0/2131.69.168.1 to 31.69.175.25431.69.175.2552,046
18331.69.176.0/2131.69.176.1 to 31.69.183.25431.69.183.2552,046
18431.69.184.0/2131.69.184.1 to 31.69.191.25431.69.191.2552,046
18531.69.192.0/2131.69.192.1 to 31.69.199.25431.69.199.2552,046
18631.69.200.0/2131.69.200.1 to 31.69.207.25431.69.207.2552,046
18731.69.208.0/2131.69.208.1 to 31.69.215.25431.69.215.2552,046
18831.69.216.0/2131.69.216.1 to 31.69.223.25431.69.223.2552,046
18931.69.224.0/2131.69.224.1 to 31.69.231.25431.69.231.2552,046
19031.69.232.0/2131.69.232.1 to 31.69.239.25431.69.239.2552,046
19131.69.240.0/2131.69.240.1 to 31.69.247.25431.69.247.2552,046
19231.69.248.0/2131.69.248.1 to 31.69.255.25431.69.255.2552,046
19331.70.0.0/2131.70.0.1 to 31.70.7.25431.70.7.2552,046
19431.70.8.0/2131.70.8.1 to 31.70.15.25431.70.15.2552,046
19531.70.16.0/2131.70.16.1 to 31.70.23.25431.70.23.2552,046
19631.70.24.0/2131.70.24.1 to 31.70.31.25431.70.31.2552,046
19731.70.32.0/2131.70.32.1 to 31.70.39.25431.70.39.2552,046
19831.70.40.0/2131.70.40.1 to 31.70.47.25431.70.47.2552,046
19931.70.48.0/2131.70.48.1 to 31.70.55.25431.70.55.2552,046
20031.70.56.0/2131.70.56.1 to 31.70.63.25431.70.63.2552,046
20131.70.64.0/2131.70.64.1 to 31.70.71.25431.70.71.2552,046
20231.70.72.0/2131.70.72.1 to 31.70.79.25431.70.79.2552,046
20331.70.80.0/2131.70.80.1 to 31.70.87.25431.70.87.2552,046
20431.70.88.0/2131.70.88.1 to 31.70.95.25431.70.95.2552,046
20531.70.96.0/2131.70.96.1 to 31.70.103.25431.70.103.2552,046
20631.70.104.0/2131.70.104.1 to 31.70.111.25431.70.111.2552,046
20731.70.112.0/2131.70.112.1 to 31.70.119.25431.70.119.2552,046
20831.70.120.0/2131.70.120.1 to 31.70.127.25431.70.127.2552,046
20931.70.128.0/2131.70.128.1 to 31.70.135.25431.70.135.2552,046
21031.70.136.0/2131.70.136.1 to 31.70.143.25431.70.143.2552,046
21131.70.144.0/2131.70.144.1 to 31.70.151.25431.70.151.2552,046
21231.70.152.0/2131.70.152.1 to 31.70.159.25431.70.159.2552,046
21331.70.160.0/2131.70.160.1 to 31.70.167.25431.70.167.2552,046
21431.70.168.0/2131.70.168.1 to 31.70.175.25431.70.175.2552,046
21531.70.176.0/2131.70.176.1 to 31.70.183.25431.70.183.2552,046
21631.70.184.0/2131.70.184.1 to 31.70.191.25431.70.191.2552,046
21731.70.192.0/2131.70.192.1 to 31.70.199.25431.70.199.2552,046
21831.70.200.0/2131.70.200.1 to 31.70.207.25431.70.207.2552,046
21931.70.208.0/2131.70.208.1 to 31.70.215.25431.70.215.2552,046
22031.70.216.0/2131.70.216.1 to 31.70.223.25431.70.223.2552,046
22131.70.224.0/2131.70.224.1 to 31.70.231.25431.70.231.2552,046
22231.70.232.0/2131.70.232.1 to 31.70.239.25431.70.239.2552,046
22331.70.240.0/2131.70.240.1 to 31.70.247.25431.70.247.2552,046
22431.70.248.0/2131.70.248.1 to 31.70.255.25431.70.255.2552,046
22531.71.0.0/2131.71.0.1 to 31.71.7.25431.71.7.2552,046
22631.71.8.0/2131.71.8.1 to 31.71.15.25431.71.15.2552,046
22731.71.16.0/2131.71.16.1 to 31.71.23.25431.71.23.2552,046
22831.71.24.0/2131.71.24.1 to 31.71.31.25431.71.31.2552,046
22931.71.32.0/2131.71.32.1 to 31.71.39.25431.71.39.2552,046
23031.71.40.0/2131.71.40.1 to 31.71.47.25431.71.47.2552,046
23131.71.48.0/2131.71.48.1 to 31.71.55.25431.71.55.2552,046
23231.71.56.0/2131.71.56.1 to 31.71.63.25431.71.63.2552,046
23331.71.64.0/2131.71.64.1 to 31.71.71.25431.71.71.2552,046
23431.71.72.0/2131.71.72.1 to 31.71.79.25431.71.79.2552,046
23531.71.80.0/2131.71.80.1 to 31.71.87.25431.71.87.2552,046
23631.71.88.0/2131.71.88.1 to 31.71.95.25431.71.95.2552,046
23731.71.96.0/2131.71.96.1 to 31.71.103.25431.71.103.2552,046
23831.71.104.0/2131.71.104.1 to 31.71.111.25431.71.111.2552,046
23931.71.112.0/2131.71.112.1 to 31.71.119.25431.71.119.2552,046
24031.71.120.0/2131.71.120.1 to 31.71.127.25431.71.127.2552,046
24131.71.128.0/2131.71.128.1 to 31.71.135.25431.71.135.2552,046
24231.71.136.0/2131.71.136.1 to 31.71.143.25431.71.143.2552,046
24331.71.144.0/2131.71.144.1 to 31.71.151.25431.71.151.2552,046
24431.71.152.0/2131.71.152.1 to 31.71.159.25431.71.159.2552,046
24531.71.160.0/2131.71.160.1 to 31.71.167.25431.71.167.2552,046
24631.71.168.0/2131.71.168.1 to 31.71.175.25431.71.175.2552,046
24731.71.176.0/2131.71.176.1 to 31.71.183.25431.71.183.2552,046
24831.71.184.0/2131.71.184.1 to 31.71.191.25431.71.191.2552,046
24931.71.192.0/2131.71.192.1 to 31.71.199.25431.71.199.2552,046
25031.71.200.0/2131.71.200.1 to 31.71.207.25431.71.207.2552,046
25131.71.208.0/2131.71.208.1 to 31.71.215.25431.71.215.2552,046
25231.71.216.0/2131.71.216.1 to 31.71.223.25431.71.223.2552,046
25331.71.224.0/2131.71.224.1 to 31.71.231.25431.71.231.2552,046
25431.71.232.0/2131.71.232.1 to 31.71.239.25431.71.239.2552,046
25531.71.240.0/2131.71.240.1 to 31.71.247.25431.71.247.2552,046
25631.71.248.0/2131.71.248.1 to 31.71.255.25431.71.255.2552,046

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.