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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.

Network64.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
64.0.0.0
Broadcast address
79.255.255.255
First usable
64.0.0.1
Last usable
79.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
A (default /8)
As numbers
Hex 40000000 · Integer 1073741824 to 1342177279
Reverse DNS zones
64.in-addr.arpa
65.in-addr.arpa
66.in-addr.arpa
67.in-addr.arpa
68.in-addr.arpa
69.in-addr.arpa
70.in-addr.arpa
71.in-addr.arpa
72.in-addr.arpa
73.in-addr.arpa
74.in-addr.arpa
75.in-addr.arpa
76.in-addr.arpa
77.in-addr.arpa
78.in-addr.arpa
79.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000000.00000000.00000000.0000000064.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network01000000.00000000.00000000.0000000064.0.0.0
Broadcast01001111.11111111.11111111.1111111179.255.255.255
Split into smaller subnets/15
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

64.0.0.0/4 makes 2,048 subnets of /15; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.0.0.0/1564.0.0.1 to 64.1.255.25464.1.255.255131,070
264.2.0.0/1564.2.0.1 to 64.3.255.25464.3.255.255131,070
364.4.0.0/1564.4.0.1 to 64.5.255.25464.5.255.255131,070
464.6.0.0/1564.6.0.1 to 64.7.255.25464.7.255.255131,070
564.8.0.0/1564.8.0.1 to 64.9.255.25464.9.255.255131,070
664.10.0.0/1564.10.0.1 to 64.11.255.25464.11.255.255131,070
764.12.0.0/1564.12.0.1 to 64.13.255.25464.13.255.255131,070
864.14.0.0/1564.14.0.1 to 64.15.255.25464.15.255.255131,070
964.16.0.0/1564.16.0.1 to 64.17.255.25464.17.255.255131,070
1064.18.0.0/1564.18.0.1 to 64.19.255.25464.19.255.255131,070
1164.20.0.0/1564.20.0.1 to 64.21.255.25464.21.255.255131,070
1264.22.0.0/1564.22.0.1 to 64.23.255.25464.23.255.255131,070
1364.24.0.0/1564.24.0.1 to 64.25.255.25464.25.255.255131,070
1464.26.0.0/1564.26.0.1 to 64.27.255.25464.27.255.255131,070
1564.28.0.0/1564.28.0.1 to 64.29.255.25464.29.255.255131,070
1664.30.0.0/1564.30.0.1 to 64.31.255.25464.31.255.255131,070
1764.32.0.0/1564.32.0.1 to 64.33.255.25464.33.255.255131,070
1864.34.0.0/1564.34.0.1 to 64.35.255.25464.35.255.255131,070
1964.36.0.0/1564.36.0.1 to 64.37.255.25464.37.255.255131,070
2064.38.0.0/1564.38.0.1 to 64.39.255.25464.39.255.255131,070
2164.40.0.0/1564.40.0.1 to 64.41.255.25464.41.255.255131,070
2264.42.0.0/1564.42.0.1 to 64.43.255.25464.43.255.255131,070
2364.44.0.0/1564.44.0.1 to 64.45.255.25464.45.255.255131,070
2464.46.0.0/1564.46.0.1 to 64.47.255.25464.47.255.255131,070
2564.48.0.0/1564.48.0.1 to 64.49.255.25464.49.255.255131,070
2664.50.0.0/1564.50.0.1 to 64.51.255.25464.51.255.255131,070
2764.52.0.0/1564.52.0.1 to 64.53.255.25464.53.255.255131,070
2864.54.0.0/1564.54.0.1 to 64.55.255.25464.55.255.255131,070
2964.56.0.0/1564.56.0.1 to 64.57.255.25464.57.255.255131,070
3064.58.0.0/1564.58.0.1 to 64.59.255.25464.59.255.255131,070
3164.60.0.0/1564.60.0.1 to 64.61.255.25464.61.255.255131,070
3264.62.0.0/1564.62.0.1 to 64.63.255.25464.63.255.255131,070
3364.64.0.0/1564.64.0.1 to 64.65.255.25464.65.255.255131,070
3464.66.0.0/1564.66.0.1 to 64.67.255.25464.67.255.255131,070
3564.68.0.0/1564.68.0.1 to 64.69.255.25464.69.255.255131,070
3664.70.0.0/1564.70.0.1 to 64.71.255.25464.71.255.255131,070
3764.72.0.0/1564.72.0.1 to 64.73.255.25464.73.255.255131,070
3864.74.0.0/1564.74.0.1 to 64.75.255.25464.75.255.255131,070
3964.76.0.0/1564.76.0.1 to 64.77.255.25464.77.255.255131,070
4064.78.0.0/1564.78.0.1 to 64.79.255.25464.79.255.255131,070
4164.80.0.0/1564.80.0.1 to 64.81.255.25464.81.255.255131,070
4264.82.0.0/1564.82.0.1 to 64.83.255.25464.83.255.255131,070
4364.84.0.0/1564.84.0.1 to 64.85.255.25464.85.255.255131,070
4464.86.0.0/1564.86.0.1 to 64.87.255.25464.87.255.255131,070
4564.88.0.0/1564.88.0.1 to 64.89.255.25464.89.255.255131,070
4664.90.0.0/1564.90.0.1 to 64.91.255.25464.91.255.255131,070
4764.92.0.0/1564.92.0.1 to 64.93.255.25464.93.255.255131,070
4864.94.0.0/1564.94.0.1 to 64.95.255.25464.95.255.255131,070
4964.96.0.0/1564.96.0.1 to 64.97.255.25464.97.255.255131,070
5064.98.0.0/1564.98.0.1 to 64.99.255.25464.99.255.255131,070
5164.100.0.0/1564.100.0.1 to 64.101.255.25464.101.255.255131,070
5264.102.0.0/1564.102.0.1 to 64.103.255.25464.103.255.255131,070
5364.104.0.0/1564.104.0.1 to 64.105.255.25464.105.255.255131,070
5464.106.0.0/1564.106.0.1 to 64.107.255.25464.107.255.255131,070
5564.108.0.0/1564.108.0.1 to 64.109.255.25464.109.255.255131,070
5664.110.0.0/1564.110.0.1 to 64.111.255.25464.111.255.255131,070
5764.112.0.0/1564.112.0.1 to 64.113.255.25464.113.255.255131,070
5864.114.0.0/1564.114.0.1 to 64.115.255.25464.115.255.255131,070
5964.116.0.0/1564.116.0.1 to 64.117.255.25464.117.255.255131,070
6064.118.0.0/1564.118.0.1 to 64.119.255.25464.119.255.255131,070
6164.120.0.0/1564.120.0.1 to 64.121.255.25464.121.255.255131,070
6264.122.0.0/1564.122.0.1 to 64.123.255.25464.123.255.255131,070
6364.124.0.0/1564.124.0.1 to 64.125.255.25464.125.255.255131,070
6464.126.0.0/1564.126.0.1 to 64.127.255.25464.127.255.255131,070
6564.128.0.0/1564.128.0.1 to 64.129.255.25464.129.255.255131,070
6664.130.0.0/1564.130.0.1 to 64.131.255.25464.131.255.255131,070
6764.132.0.0/1564.132.0.1 to 64.133.255.25464.133.255.255131,070
6864.134.0.0/1564.134.0.1 to 64.135.255.25464.135.255.255131,070
6964.136.0.0/1564.136.0.1 to 64.137.255.25464.137.255.255131,070
7064.138.0.0/1564.138.0.1 to 64.139.255.25464.139.255.255131,070
7164.140.0.0/1564.140.0.1 to 64.141.255.25464.141.255.255131,070
7264.142.0.0/1564.142.0.1 to 64.143.255.25464.143.255.255131,070
7364.144.0.0/1564.144.0.1 to 64.145.255.25464.145.255.255131,070
7464.146.0.0/1564.146.0.1 to 64.147.255.25464.147.255.255131,070
7564.148.0.0/1564.148.0.1 to 64.149.255.25464.149.255.255131,070
7664.150.0.0/1564.150.0.1 to 64.151.255.25464.151.255.255131,070
7764.152.0.0/1564.152.0.1 to 64.153.255.25464.153.255.255131,070
7864.154.0.0/1564.154.0.1 to 64.155.255.25464.155.255.255131,070
7964.156.0.0/1564.156.0.1 to 64.157.255.25464.157.255.255131,070
8064.158.0.0/1564.158.0.1 to 64.159.255.25464.159.255.255131,070
8164.160.0.0/1564.160.0.1 to 64.161.255.25464.161.255.255131,070
8264.162.0.0/1564.162.0.1 to 64.163.255.25464.163.255.255131,070
8364.164.0.0/1564.164.0.1 to 64.165.255.25464.165.255.255131,070
8464.166.0.0/1564.166.0.1 to 64.167.255.25464.167.255.255131,070
8564.168.0.0/1564.168.0.1 to 64.169.255.25464.169.255.255131,070
8664.170.0.0/1564.170.0.1 to 64.171.255.25464.171.255.255131,070
8764.172.0.0/1564.172.0.1 to 64.173.255.25464.173.255.255131,070
8864.174.0.0/1564.174.0.1 to 64.175.255.25464.175.255.255131,070
8964.176.0.0/1564.176.0.1 to 64.177.255.25464.177.255.255131,070
9064.178.0.0/1564.178.0.1 to 64.179.255.25464.179.255.255131,070
9164.180.0.0/1564.180.0.1 to 64.181.255.25464.181.255.255131,070
9264.182.0.0/1564.182.0.1 to 64.183.255.25464.183.255.255131,070
9364.184.0.0/1564.184.0.1 to 64.185.255.25464.185.255.255131,070
9464.186.0.0/1564.186.0.1 to 64.187.255.25464.187.255.255131,070
9564.188.0.0/1564.188.0.1 to 64.189.255.25464.189.255.255131,070
9664.190.0.0/1564.190.0.1 to 64.191.255.25464.191.255.255131,070
9764.192.0.0/1564.192.0.1 to 64.193.255.25464.193.255.255131,070
9864.194.0.0/1564.194.0.1 to 64.195.255.25464.195.255.255131,070
9964.196.0.0/1564.196.0.1 to 64.197.255.25464.197.255.255131,070
10064.198.0.0/1564.198.0.1 to 64.199.255.25464.199.255.255131,070
10164.200.0.0/1564.200.0.1 to 64.201.255.25464.201.255.255131,070
10264.202.0.0/1564.202.0.1 to 64.203.255.25464.203.255.255131,070
10364.204.0.0/1564.204.0.1 to 64.205.255.25464.205.255.255131,070
10464.206.0.0/1564.206.0.1 to 64.207.255.25464.207.255.255131,070
10564.208.0.0/1564.208.0.1 to 64.209.255.25464.209.255.255131,070
10664.210.0.0/1564.210.0.1 to 64.211.255.25464.211.255.255131,070
10764.212.0.0/1564.212.0.1 to 64.213.255.25464.213.255.255131,070
10864.214.0.0/1564.214.0.1 to 64.215.255.25464.215.255.255131,070
10964.216.0.0/1564.216.0.1 to 64.217.255.25464.217.255.255131,070
11064.218.0.0/1564.218.0.1 to 64.219.255.25464.219.255.255131,070
11164.220.0.0/1564.220.0.1 to 64.221.255.25464.221.255.255131,070
11264.222.0.0/1564.222.0.1 to 64.223.255.25464.223.255.255131,070
11364.224.0.0/1564.224.0.1 to 64.225.255.25464.225.255.255131,070
11464.226.0.0/1564.226.0.1 to 64.227.255.25464.227.255.255131,070
11564.228.0.0/1564.228.0.1 to 64.229.255.25464.229.255.255131,070
11664.230.0.0/1564.230.0.1 to 64.231.255.25464.231.255.255131,070
11764.232.0.0/1564.232.0.1 to 64.233.255.25464.233.255.255131,070
11864.234.0.0/1564.234.0.1 to 64.235.255.25464.235.255.255131,070
11964.236.0.0/1564.236.0.1 to 64.237.255.25464.237.255.255131,070
12064.238.0.0/1564.238.0.1 to 64.239.255.25464.239.255.255131,070
12164.240.0.0/1564.240.0.1 to 64.241.255.25464.241.255.255131,070
12264.242.0.0/1564.242.0.1 to 64.243.255.25464.243.255.255131,070
12364.244.0.0/1564.244.0.1 to 64.245.255.25464.245.255.255131,070
12464.246.0.0/1564.246.0.1 to 64.247.255.25464.247.255.255131,070
12564.248.0.0/1564.248.0.1 to 64.249.255.25464.249.255.255131,070
12664.250.0.0/1564.250.0.1 to 64.251.255.25464.251.255.255131,070
12764.252.0.0/1564.252.0.1 to 64.253.255.25464.253.255.255131,070
12864.254.0.0/1564.254.0.1 to 64.255.255.25464.255.255.255131,070
12965.0.0.0/1565.0.0.1 to 65.1.255.25465.1.255.255131,070
13065.2.0.0/1565.2.0.1 to 65.3.255.25465.3.255.255131,070
13165.4.0.0/1565.4.0.1 to 65.5.255.25465.5.255.255131,070
13265.6.0.0/1565.6.0.1 to 65.7.255.25465.7.255.255131,070
13365.8.0.0/1565.8.0.1 to 65.9.255.25465.9.255.255131,070
13465.10.0.0/1565.10.0.1 to 65.11.255.25465.11.255.255131,070
13565.12.0.0/1565.12.0.1 to 65.13.255.25465.13.255.255131,070
13665.14.0.0/1565.14.0.1 to 65.15.255.25465.15.255.255131,070
13765.16.0.0/1565.16.0.1 to 65.17.255.25465.17.255.255131,070
13865.18.0.0/1565.18.0.1 to 65.19.255.25465.19.255.255131,070
13965.20.0.0/1565.20.0.1 to 65.21.255.25465.21.255.255131,070
14065.22.0.0/1565.22.0.1 to 65.23.255.25465.23.255.255131,070
14165.24.0.0/1565.24.0.1 to 65.25.255.25465.25.255.255131,070
14265.26.0.0/1565.26.0.1 to 65.27.255.25465.27.255.255131,070
14365.28.0.0/1565.28.0.1 to 65.29.255.25465.29.255.255131,070
14465.30.0.0/1565.30.0.1 to 65.31.255.25465.31.255.255131,070
14565.32.0.0/1565.32.0.1 to 65.33.255.25465.33.255.255131,070
14665.34.0.0/1565.34.0.1 to 65.35.255.25465.35.255.255131,070
14765.36.0.0/1565.36.0.1 to 65.37.255.25465.37.255.255131,070
14865.38.0.0/1565.38.0.1 to 65.39.255.25465.39.255.255131,070
14965.40.0.0/1565.40.0.1 to 65.41.255.25465.41.255.255131,070
15065.42.0.0/1565.42.0.1 to 65.43.255.25465.43.255.255131,070
15165.44.0.0/1565.44.0.1 to 65.45.255.25465.45.255.255131,070
15265.46.0.0/1565.46.0.1 to 65.47.255.25465.47.255.255131,070
15365.48.0.0/1565.48.0.1 to 65.49.255.25465.49.255.255131,070
15465.50.0.0/1565.50.0.1 to 65.51.255.25465.51.255.255131,070
15565.52.0.0/1565.52.0.1 to 65.53.255.25465.53.255.255131,070
15665.54.0.0/1565.54.0.1 to 65.55.255.25465.55.255.255131,070
15765.56.0.0/1565.56.0.1 to 65.57.255.25465.57.255.255131,070
15865.58.0.0/1565.58.0.1 to 65.59.255.25465.59.255.255131,070
15965.60.0.0/1565.60.0.1 to 65.61.255.25465.61.255.255131,070
16065.62.0.0/1565.62.0.1 to 65.63.255.25465.63.255.255131,070
16165.64.0.0/1565.64.0.1 to 65.65.255.25465.65.255.255131,070
16265.66.0.0/1565.66.0.1 to 65.67.255.25465.67.255.255131,070
16365.68.0.0/1565.68.0.1 to 65.69.255.25465.69.255.255131,070
16465.70.0.0/1565.70.0.1 to 65.71.255.25465.71.255.255131,070
16565.72.0.0/1565.72.0.1 to 65.73.255.25465.73.255.255131,070
16665.74.0.0/1565.74.0.1 to 65.75.255.25465.75.255.255131,070
16765.76.0.0/1565.76.0.1 to 65.77.255.25465.77.255.255131,070
16865.78.0.0/1565.78.0.1 to 65.79.255.25465.79.255.255131,070
16965.80.0.0/1565.80.0.1 to 65.81.255.25465.81.255.255131,070
17065.82.0.0/1565.82.0.1 to 65.83.255.25465.83.255.255131,070
17165.84.0.0/1565.84.0.1 to 65.85.255.25465.85.255.255131,070
17265.86.0.0/1565.86.0.1 to 65.87.255.25465.87.255.255131,070
17365.88.0.0/1565.88.0.1 to 65.89.255.25465.89.255.255131,070
17465.90.0.0/1565.90.0.1 to 65.91.255.25465.91.255.255131,070
17565.92.0.0/1565.92.0.1 to 65.93.255.25465.93.255.255131,070
17665.94.0.0/1565.94.0.1 to 65.95.255.25465.95.255.255131,070
17765.96.0.0/1565.96.0.1 to 65.97.255.25465.97.255.255131,070
17865.98.0.0/1565.98.0.1 to 65.99.255.25465.99.255.255131,070
17965.100.0.0/1565.100.0.1 to 65.101.255.25465.101.255.255131,070
18065.102.0.0/1565.102.0.1 to 65.103.255.25465.103.255.255131,070
18165.104.0.0/1565.104.0.1 to 65.105.255.25465.105.255.255131,070
18265.106.0.0/1565.106.0.1 to 65.107.255.25465.107.255.255131,070
18365.108.0.0/1565.108.0.1 to 65.109.255.25465.109.255.255131,070
18465.110.0.0/1565.110.0.1 to 65.111.255.25465.111.255.255131,070
18565.112.0.0/1565.112.0.1 to 65.113.255.25465.113.255.255131,070
18665.114.0.0/1565.114.0.1 to 65.115.255.25465.115.255.255131,070
18765.116.0.0/1565.116.0.1 to 65.117.255.25465.117.255.255131,070
18865.118.0.0/1565.118.0.1 to 65.119.255.25465.119.255.255131,070
18965.120.0.0/1565.120.0.1 to 65.121.255.25465.121.255.255131,070
19065.122.0.0/1565.122.0.1 to 65.123.255.25465.123.255.255131,070
19165.124.0.0/1565.124.0.1 to 65.125.255.25465.125.255.255131,070
19265.126.0.0/1565.126.0.1 to 65.127.255.25465.127.255.255131,070
19365.128.0.0/1565.128.0.1 to 65.129.255.25465.129.255.255131,070
19465.130.0.0/1565.130.0.1 to 65.131.255.25465.131.255.255131,070
19565.132.0.0/1565.132.0.1 to 65.133.255.25465.133.255.255131,070
19665.134.0.0/1565.134.0.1 to 65.135.255.25465.135.255.255131,070
19765.136.0.0/1565.136.0.1 to 65.137.255.25465.137.255.255131,070
19865.138.0.0/1565.138.0.1 to 65.139.255.25465.139.255.255131,070
19965.140.0.0/1565.140.0.1 to 65.141.255.25465.141.255.255131,070
20065.142.0.0/1565.142.0.1 to 65.143.255.25465.143.255.255131,070
20165.144.0.0/1565.144.0.1 to 65.145.255.25465.145.255.255131,070
20265.146.0.0/1565.146.0.1 to 65.147.255.25465.147.255.255131,070
20365.148.0.0/1565.148.0.1 to 65.149.255.25465.149.255.255131,070
20465.150.0.0/1565.150.0.1 to 65.151.255.25465.151.255.255131,070
20565.152.0.0/1565.152.0.1 to 65.153.255.25465.153.255.255131,070
20665.154.0.0/1565.154.0.1 to 65.155.255.25465.155.255.255131,070
20765.156.0.0/1565.156.0.1 to 65.157.255.25465.157.255.255131,070
20865.158.0.0/1565.158.0.1 to 65.159.255.25465.159.255.255131,070
20965.160.0.0/1565.160.0.1 to 65.161.255.25465.161.255.255131,070
21065.162.0.0/1565.162.0.1 to 65.163.255.25465.163.255.255131,070
21165.164.0.0/1565.164.0.1 to 65.165.255.25465.165.255.255131,070
21265.166.0.0/1565.166.0.1 to 65.167.255.25465.167.255.255131,070
21365.168.0.0/1565.168.0.1 to 65.169.255.25465.169.255.255131,070
21465.170.0.0/1565.170.0.1 to 65.171.255.25465.171.255.255131,070
21565.172.0.0/1565.172.0.1 to 65.173.255.25465.173.255.255131,070
21665.174.0.0/1565.174.0.1 to 65.175.255.25465.175.255.255131,070
21765.176.0.0/1565.176.0.1 to 65.177.255.25465.177.255.255131,070
21865.178.0.0/1565.178.0.1 to 65.179.255.25465.179.255.255131,070
21965.180.0.0/1565.180.0.1 to 65.181.255.25465.181.255.255131,070
22065.182.0.0/1565.182.0.1 to 65.183.255.25465.183.255.255131,070
22165.184.0.0/1565.184.0.1 to 65.185.255.25465.185.255.255131,070
22265.186.0.0/1565.186.0.1 to 65.187.255.25465.187.255.255131,070
22365.188.0.0/1565.188.0.1 to 65.189.255.25465.189.255.255131,070
22465.190.0.0/1565.190.0.1 to 65.191.255.25465.191.255.255131,070
22565.192.0.0/1565.192.0.1 to 65.193.255.25465.193.255.255131,070
22665.194.0.0/1565.194.0.1 to 65.195.255.25465.195.255.255131,070
22765.196.0.0/1565.196.0.1 to 65.197.255.25465.197.255.255131,070
22865.198.0.0/1565.198.0.1 to 65.199.255.25465.199.255.255131,070
22965.200.0.0/1565.200.0.1 to 65.201.255.25465.201.255.255131,070
23065.202.0.0/1565.202.0.1 to 65.203.255.25465.203.255.255131,070
23165.204.0.0/1565.204.0.1 to 65.205.255.25465.205.255.255131,070
23265.206.0.0/1565.206.0.1 to 65.207.255.25465.207.255.255131,070
23365.208.0.0/1565.208.0.1 to 65.209.255.25465.209.255.255131,070
23465.210.0.0/1565.210.0.1 to 65.211.255.25465.211.255.255131,070
23565.212.0.0/1565.212.0.1 to 65.213.255.25465.213.255.255131,070
23665.214.0.0/1565.214.0.1 to 65.215.255.25465.215.255.255131,070
23765.216.0.0/1565.216.0.1 to 65.217.255.25465.217.255.255131,070
23865.218.0.0/1565.218.0.1 to 65.219.255.25465.219.255.255131,070
23965.220.0.0/1565.220.0.1 to 65.221.255.25465.221.255.255131,070
24065.222.0.0/1565.222.0.1 to 65.223.255.25465.223.255.255131,070
24165.224.0.0/1565.224.0.1 to 65.225.255.25465.225.255.255131,070
24265.226.0.0/1565.226.0.1 to 65.227.255.25465.227.255.255131,070
24365.228.0.0/1565.228.0.1 to 65.229.255.25465.229.255.255131,070
24465.230.0.0/1565.230.0.1 to 65.231.255.25465.231.255.255131,070
24565.232.0.0/1565.232.0.1 to 65.233.255.25465.233.255.255131,070
24665.234.0.0/1565.234.0.1 to 65.235.255.25465.235.255.255131,070
24765.236.0.0/1565.236.0.1 to 65.237.255.25465.237.255.255131,070
24865.238.0.0/1565.238.0.1 to 65.239.255.25465.239.255.255131,070
24965.240.0.0/1565.240.0.1 to 65.241.255.25465.241.255.255131,070
25065.242.0.0/1565.242.0.1 to 65.243.255.25465.243.255.255131,070
25165.244.0.0/1565.244.0.1 to 65.245.255.25465.245.255.255131,070
25265.246.0.0/1565.246.0.1 to 65.247.255.25465.247.255.255131,070
25365.248.0.0/1565.248.0.1 to 65.249.255.25465.249.255.255131,070
25465.250.0.0/1565.250.0.1 to 65.251.255.25465.251.255.255131,070
25565.252.0.0/1565.252.0.1 to 65.253.255.25465.253.255.255131,070
25665.254.0.0/1565.254.0.1 to 65.255.255.25465.255.255.255131,070

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.