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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.

Network23.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
23.0.0.0
Broadcast address
23.255.255.255
First usable
23.0.0.1
Last usable
23.255.255.254
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 17000000 · Integer 385875968 to 402653183
Reverse DNS zone
23.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010111..00000000.00000000.0000000023.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00010111..00000000.00000000.0000000023.0.0.0
Broadcast00010111..11111111.11111111.1111111123.255.255.255
Split into smaller subnets/16
/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)

23.0.0.0/8 makes 256 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.0.0.0/1623.0.0.1 to 23.0.255.25423.0.255.25565,534
223.1.0.0/1623.1.0.1 to 23.1.255.25423.1.255.25565,534
323.2.0.0/1623.2.0.1 to 23.2.255.25423.2.255.25565,534
423.3.0.0/1623.3.0.1 to 23.3.255.25423.3.255.25565,534
523.4.0.0/1623.4.0.1 to 23.4.255.25423.4.255.25565,534
623.5.0.0/1623.5.0.1 to 23.5.255.25423.5.255.25565,534
723.6.0.0/1623.6.0.1 to 23.6.255.25423.6.255.25565,534
823.7.0.0/1623.7.0.1 to 23.7.255.25423.7.255.25565,534
923.8.0.0/1623.8.0.1 to 23.8.255.25423.8.255.25565,534
1023.9.0.0/1623.9.0.1 to 23.9.255.25423.9.255.25565,534
1123.10.0.0/1623.10.0.1 to 23.10.255.25423.10.255.25565,534
1223.11.0.0/1623.11.0.1 to 23.11.255.25423.11.255.25565,534
1323.12.0.0/1623.12.0.1 to 23.12.255.25423.12.255.25565,534
1423.13.0.0/1623.13.0.1 to 23.13.255.25423.13.255.25565,534
1523.14.0.0/1623.14.0.1 to 23.14.255.25423.14.255.25565,534
1623.15.0.0/1623.15.0.1 to 23.15.255.25423.15.255.25565,534
1723.16.0.0/1623.16.0.1 to 23.16.255.25423.16.255.25565,534
1823.17.0.0/1623.17.0.1 to 23.17.255.25423.17.255.25565,534
1923.18.0.0/1623.18.0.1 to 23.18.255.25423.18.255.25565,534
2023.19.0.0/1623.19.0.1 to 23.19.255.25423.19.255.25565,534
2123.20.0.0/1623.20.0.1 to 23.20.255.25423.20.255.25565,534
2223.21.0.0/1623.21.0.1 to 23.21.255.25423.21.255.25565,534
2323.22.0.0/1623.22.0.1 to 23.22.255.25423.22.255.25565,534
2423.23.0.0/1623.23.0.1 to 23.23.255.25423.23.255.25565,534
2523.24.0.0/1623.24.0.1 to 23.24.255.25423.24.255.25565,534
2623.25.0.0/1623.25.0.1 to 23.25.255.25423.25.255.25565,534
2723.26.0.0/1623.26.0.1 to 23.26.255.25423.26.255.25565,534
2823.27.0.0/1623.27.0.1 to 23.27.255.25423.27.255.25565,534
2923.28.0.0/1623.28.0.1 to 23.28.255.25423.28.255.25565,534
3023.29.0.0/1623.29.0.1 to 23.29.255.25423.29.255.25565,534
3123.30.0.0/1623.30.0.1 to 23.30.255.25423.30.255.25565,534
3223.31.0.0/1623.31.0.1 to 23.31.255.25423.31.255.25565,534
3323.32.0.0/1623.32.0.1 to 23.32.255.25423.32.255.25565,534
3423.33.0.0/1623.33.0.1 to 23.33.255.25423.33.255.25565,534
3523.34.0.0/1623.34.0.1 to 23.34.255.25423.34.255.25565,534
3623.35.0.0/1623.35.0.1 to 23.35.255.25423.35.255.25565,534
3723.36.0.0/1623.36.0.1 to 23.36.255.25423.36.255.25565,534
3823.37.0.0/1623.37.0.1 to 23.37.255.25423.37.255.25565,534
3923.38.0.0/1623.38.0.1 to 23.38.255.25423.38.255.25565,534
4023.39.0.0/1623.39.0.1 to 23.39.255.25423.39.255.25565,534
4123.40.0.0/1623.40.0.1 to 23.40.255.25423.40.255.25565,534
4223.41.0.0/1623.41.0.1 to 23.41.255.25423.41.255.25565,534
4323.42.0.0/1623.42.0.1 to 23.42.255.25423.42.255.25565,534
4423.43.0.0/1623.43.0.1 to 23.43.255.25423.43.255.25565,534
4523.44.0.0/1623.44.0.1 to 23.44.255.25423.44.255.25565,534
4623.45.0.0/1623.45.0.1 to 23.45.255.25423.45.255.25565,534
4723.46.0.0/1623.46.0.1 to 23.46.255.25423.46.255.25565,534
4823.47.0.0/1623.47.0.1 to 23.47.255.25423.47.255.25565,534
4923.48.0.0/1623.48.0.1 to 23.48.255.25423.48.255.25565,534
5023.49.0.0/1623.49.0.1 to 23.49.255.25423.49.255.25565,534
5123.50.0.0/1623.50.0.1 to 23.50.255.25423.50.255.25565,534
5223.51.0.0/1623.51.0.1 to 23.51.255.25423.51.255.25565,534
5323.52.0.0/1623.52.0.1 to 23.52.255.25423.52.255.25565,534
5423.53.0.0/1623.53.0.1 to 23.53.255.25423.53.255.25565,534
5523.54.0.0/1623.54.0.1 to 23.54.255.25423.54.255.25565,534
5623.55.0.0/1623.55.0.1 to 23.55.255.25423.55.255.25565,534
5723.56.0.0/1623.56.0.1 to 23.56.255.25423.56.255.25565,534
5823.57.0.0/1623.57.0.1 to 23.57.255.25423.57.255.25565,534
5923.58.0.0/1623.58.0.1 to 23.58.255.25423.58.255.25565,534
6023.59.0.0/1623.59.0.1 to 23.59.255.25423.59.255.25565,534
6123.60.0.0/1623.60.0.1 to 23.60.255.25423.60.255.25565,534
6223.61.0.0/1623.61.0.1 to 23.61.255.25423.61.255.25565,534
6323.62.0.0/1623.62.0.1 to 23.62.255.25423.62.255.25565,534
6423.63.0.0/1623.63.0.1 to 23.63.255.25423.63.255.25565,534
6523.64.0.0/1623.64.0.1 to 23.64.255.25423.64.255.25565,534
6623.65.0.0/1623.65.0.1 to 23.65.255.25423.65.255.25565,534
6723.66.0.0/1623.66.0.1 to 23.66.255.25423.66.255.25565,534
6823.67.0.0/1623.67.0.1 to 23.67.255.25423.67.255.25565,534
6923.68.0.0/1623.68.0.1 to 23.68.255.25423.68.255.25565,534
7023.69.0.0/1623.69.0.1 to 23.69.255.25423.69.255.25565,534
7123.70.0.0/1623.70.0.1 to 23.70.255.25423.70.255.25565,534
7223.71.0.0/1623.71.0.1 to 23.71.255.25423.71.255.25565,534
7323.72.0.0/1623.72.0.1 to 23.72.255.25423.72.255.25565,534
7423.73.0.0/1623.73.0.1 to 23.73.255.25423.73.255.25565,534
7523.74.0.0/1623.74.0.1 to 23.74.255.25423.74.255.25565,534
7623.75.0.0/1623.75.0.1 to 23.75.255.25423.75.255.25565,534
7723.76.0.0/1623.76.0.1 to 23.76.255.25423.76.255.25565,534
7823.77.0.0/1623.77.0.1 to 23.77.255.25423.77.255.25565,534
7923.78.0.0/1623.78.0.1 to 23.78.255.25423.78.255.25565,534
8023.79.0.0/1623.79.0.1 to 23.79.255.25423.79.255.25565,534
8123.80.0.0/1623.80.0.1 to 23.80.255.25423.80.255.25565,534
8223.81.0.0/1623.81.0.1 to 23.81.255.25423.81.255.25565,534
8323.82.0.0/1623.82.0.1 to 23.82.255.25423.82.255.25565,534
8423.83.0.0/1623.83.0.1 to 23.83.255.25423.83.255.25565,534
8523.84.0.0/1623.84.0.1 to 23.84.255.25423.84.255.25565,534
8623.85.0.0/1623.85.0.1 to 23.85.255.25423.85.255.25565,534
8723.86.0.0/1623.86.0.1 to 23.86.255.25423.86.255.25565,534
8823.87.0.0/1623.87.0.1 to 23.87.255.25423.87.255.25565,534
8923.88.0.0/1623.88.0.1 to 23.88.255.25423.88.255.25565,534
9023.89.0.0/1623.89.0.1 to 23.89.255.25423.89.255.25565,534
9123.90.0.0/1623.90.0.1 to 23.90.255.25423.90.255.25565,534
9223.91.0.0/1623.91.0.1 to 23.91.255.25423.91.255.25565,534
9323.92.0.0/1623.92.0.1 to 23.92.255.25423.92.255.25565,534
9423.93.0.0/1623.93.0.1 to 23.93.255.25423.93.255.25565,534
9523.94.0.0/1623.94.0.1 to 23.94.255.25423.94.255.25565,534
9623.95.0.0/1623.95.0.1 to 23.95.255.25423.95.255.25565,534
9723.96.0.0/1623.96.0.1 to 23.96.255.25423.96.255.25565,534
9823.97.0.0/1623.97.0.1 to 23.97.255.25423.97.255.25565,534
9923.98.0.0/1623.98.0.1 to 23.98.255.25423.98.255.25565,534
10023.99.0.0/1623.99.0.1 to 23.99.255.25423.99.255.25565,534
10123.100.0.0/1623.100.0.1 to 23.100.255.25423.100.255.25565,534
10223.101.0.0/1623.101.0.1 to 23.101.255.25423.101.255.25565,534
10323.102.0.0/1623.102.0.1 to 23.102.255.25423.102.255.25565,534
10423.103.0.0/1623.103.0.1 to 23.103.255.25423.103.255.25565,534
10523.104.0.0/1623.104.0.1 to 23.104.255.25423.104.255.25565,534
10623.105.0.0/1623.105.0.1 to 23.105.255.25423.105.255.25565,534
10723.106.0.0/1623.106.0.1 to 23.106.255.25423.106.255.25565,534
10823.107.0.0/1623.107.0.1 to 23.107.255.25423.107.255.25565,534
10923.108.0.0/1623.108.0.1 to 23.108.255.25423.108.255.25565,534
11023.109.0.0/1623.109.0.1 to 23.109.255.25423.109.255.25565,534
11123.110.0.0/1623.110.0.1 to 23.110.255.25423.110.255.25565,534
11223.111.0.0/1623.111.0.1 to 23.111.255.25423.111.255.25565,534
11323.112.0.0/1623.112.0.1 to 23.112.255.25423.112.255.25565,534
11423.113.0.0/1623.113.0.1 to 23.113.255.25423.113.255.25565,534
11523.114.0.0/1623.114.0.1 to 23.114.255.25423.114.255.25565,534
11623.115.0.0/1623.115.0.1 to 23.115.255.25423.115.255.25565,534
11723.116.0.0/1623.116.0.1 to 23.116.255.25423.116.255.25565,534
11823.117.0.0/1623.117.0.1 to 23.117.255.25423.117.255.25565,534
11923.118.0.0/1623.118.0.1 to 23.118.255.25423.118.255.25565,534
12023.119.0.0/1623.119.0.1 to 23.119.255.25423.119.255.25565,534
12123.120.0.0/1623.120.0.1 to 23.120.255.25423.120.255.25565,534
12223.121.0.0/1623.121.0.1 to 23.121.255.25423.121.255.25565,534
12323.122.0.0/1623.122.0.1 to 23.122.255.25423.122.255.25565,534
12423.123.0.0/1623.123.0.1 to 23.123.255.25423.123.255.25565,534
12523.124.0.0/1623.124.0.1 to 23.124.255.25423.124.255.25565,534
12623.125.0.0/1623.125.0.1 to 23.125.255.25423.125.255.25565,534
12723.126.0.0/1623.126.0.1 to 23.126.255.25423.126.255.25565,534
12823.127.0.0/1623.127.0.1 to 23.127.255.25423.127.255.25565,534
12923.128.0.0/1623.128.0.1 to 23.128.255.25423.128.255.25565,534
13023.129.0.0/1623.129.0.1 to 23.129.255.25423.129.255.25565,534
13123.130.0.0/1623.130.0.1 to 23.130.255.25423.130.255.25565,534
13223.131.0.0/1623.131.0.1 to 23.131.255.25423.131.255.25565,534
13323.132.0.0/1623.132.0.1 to 23.132.255.25423.132.255.25565,534
13423.133.0.0/1623.133.0.1 to 23.133.255.25423.133.255.25565,534
13523.134.0.0/1623.134.0.1 to 23.134.255.25423.134.255.25565,534
13623.135.0.0/1623.135.0.1 to 23.135.255.25423.135.255.25565,534
13723.136.0.0/1623.136.0.1 to 23.136.255.25423.136.255.25565,534
13823.137.0.0/1623.137.0.1 to 23.137.255.25423.137.255.25565,534
13923.138.0.0/1623.138.0.1 to 23.138.255.25423.138.255.25565,534
14023.139.0.0/1623.139.0.1 to 23.139.255.25423.139.255.25565,534
14123.140.0.0/1623.140.0.1 to 23.140.255.25423.140.255.25565,534
14223.141.0.0/1623.141.0.1 to 23.141.255.25423.141.255.25565,534
14323.142.0.0/1623.142.0.1 to 23.142.255.25423.142.255.25565,534
14423.143.0.0/1623.143.0.1 to 23.143.255.25423.143.255.25565,534
14523.144.0.0/1623.144.0.1 to 23.144.255.25423.144.255.25565,534
14623.145.0.0/1623.145.0.1 to 23.145.255.25423.145.255.25565,534
14723.146.0.0/1623.146.0.1 to 23.146.255.25423.146.255.25565,534
14823.147.0.0/1623.147.0.1 to 23.147.255.25423.147.255.25565,534
14923.148.0.0/1623.148.0.1 to 23.148.255.25423.148.255.25565,534
15023.149.0.0/1623.149.0.1 to 23.149.255.25423.149.255.25565,534
15123.150.0.0/1623.150.0.1 to 23.150.255.25423.150.255.25565,534
15223.151.0.0/1623.151.0.1 to 23.151.255.25423.151.255.25565,534
15323.152.0.0/1623.152.0.1 to 23.152.255.25423.152.255.25565,534
15423.153.0.0/1623.153.0.1 to 23.153.255.25423.153.255.25565,534
15523.154.0.0/1623.154.0.1 to 23.154.255.25423.154.255.25565,534
15623.155.0.0/1623.155.0.1 to 23.155.255.25423.155.255.25565,534
15723.156.0.0/1623.156.0.1 to 23.156.255.25423.156.255.25565,534
15823.157.0.0/1623.157.0.1 to 23.157.255.25423.157.255.25565,534
15923.158.0.0/1623.158.0.1 to 23.158.255.25423.158.255.25565,534
16023.159.0.0/1623.159.0.1 to 23.159.255.25423.159.255.25565,534
16123.160.0.0/1623.160.0.1 to 23.160.255.25423.160.255.25565,534
16223.161.0.0/1623.161.0.1 to 23.161.255.25423.161.255.25565,534
16323.162.0.0/1623.162.0.1 to 23.162.255.25423.162.255.25565,534
16423.163.0.0/1623.163.0.1 to 23.163.255.25423.163.255.25565,534
16523.164.0.0/1623.164.0.1 to 23.164.255.25423.164.255.25565,534
16623.165.0.0/1623.165.0.1 to 23.165.255.25423.165.255.25565,534
16723.166.0.0/1623.166.0.1 to 23.166.255.25423.166.255.25565,534
16823.167.0.0/1623.167.0.1 to 23.167.255.25423.167.255.25565,534
16923.168.0.0/1623.168.0.1 to 23.168.255.25423.168.255.25565,534
17023.169.0.0/1623.169.0.1 to 23.169.255.25423.169.255.25565,534
17123.170.0.0/1623.170.0.1 to 23.170.255.25423.170.255.25565,534
17223.171.0.0/1623.171.0.1 to 23.171.255.25423.171.255.25565,534
17323.172.0.0/1623.172.0.1 to 23.172.255.25423.172.255.25565,534
17423.173.0.0/1623.173.0.1 to 23.173.255.25423.173.255.25565,534
17523.174.0.0/1623.174.0.1 to 23.174.255.25423.174.255.25565,534
17623.175.0.0/1623.175.0.1 to 23.175.255.25423.175.255.25565,534
17723.176.0.0/1623.176.0.1 to 23.176.255.25423.176.255.25565,534
17823.177.0.0/1623.177.0.1 to 23.177.255.25423.177.255.25565,534
17923.178.0.0/1623.178.0.1 to 23.178.255.25423.178.255.25565,534
18023.179.0.0/1623.179.0.1 to 23.179.255.25423.179.255.25565,534
18123.180.0.0/1623.180.0.1 to 23.180.255.25423.180.255.25565,534
18223.181.0.0/1623.181.0.1 to 23.181.255.25423.181.255.25565,534
18323.182.0.0/1623.182.0.1 to 23.182.255.25423.182.255.25565,534
18423.183.0.0/1623.183.0.1 to 23.183.255.25423.183.255.25565,534
18523.184.0.0/1623.184.0.1 to 23.184.255.25423.184.255.25565,534
18623.185.0.0/1623.185.0.1 to 23.185.255.25423.185.255.25565,534
18723.186.0.0/1623.186.0.1 to 23.186.255.25423.186.255.25565,534
18823.187.0.0/1623.187.0.1 to 23.187.255.25423.187.255.25565,534
18923.188.0.0/1623.188.0.1 to 23.188.255.25423.188.255.25565,534
19023.189.0.0/1623.189.0.1 to 23.189.255.25423.189.255.25565,534
19123.190.0.0/1623.190.0.1 to 23.190.255.25423.190.255.25565,534
19223.191.0.0/1623.191.0.1 to 23.191.255.25423.191.255.25565,534
19323.192.0.0/1623.192.0.1 to 23.192.255.25423.192.255.25565,534
19423.193.0.0/1623.193.0.1 to 23.193.255.25423.193.255.25565,534
19523.194.0.0/1623.194.0.1 to 23.194.255.25423.194.255.25565,534
19623.195.0.0/1623.195.0.1 to 23.195.255.25423.195.255.25565,534
19723.196.0.0/1623.196.0.1 to 23.196.255.25423.196.255.25565,534
19823.197.0.0/1623.197.0.1 to 23.197.255.25423.197.255.25565,534
19923.198.0.0/1623.198.0.1 to 23.198.255.25423.198.255.25565,534
20023.199.0.0/1623.199.0.1 to 23.199.255.25423.199.255.25565,534
20123.200.0.0/1623.200.0.1 to 23.200.255.25423.200.255.25565,534
20223.201.0.0/1623.201.0.1 to 23.201.255.25423.201.255.25565,534
20323.202.0.0/1623.202.0.1 to 23.202.255.25423.202.255.25565,534
20423.203.0.0/1623.203.0.1 to 23.203.255.25423.203.255.25565,534
20523.204.0.0/1623.204.0.1 to 23.204.255.25423.204.255.25565,534
20623.205.0.0/1623.205.0.1 to 23.205.255.25423.205.255.25565,534
20723.206.0.0/1623.206.0.1 to 23.206.255.25423.206.255.25565,534
20823.207.0.0/1623.207.0.1 to 23.207.255.25423.207.255.25565,534
20923.208.0.0/1623.208.0.1 to 23.208.255.25423.208.255.25565,534
21023.209.0.0/1623.209.0.1 to 23.209.255.25423.209.255.25565,534
21123.210.0.0/1623.210.0.1 to 23.210.255.25423.210.255.25565,534
21223.211.0.0/1623.211.0.1 to 23.211.255.25423.211.255.25565,534
21323.212.0.0/1623.212.0.1 to 23.212.255.25423.212.255.25565,534
21423.213.0.0/1623.213.0.1 to 23.213.255.25423.213.255.25565,534
21523.214.0.0/1623.214.0.1 to 23.214.255.25423.214.255.25565,534
21623.215.0.0/1623.215.0.1 to 23.215.255.25423.215.255.25565,534
21723.216.0.0/1623.216.0.1 to 23.216.255.25423.216.255.25565,534
21823.217.0.0/1623.217.0.1 to 23.217.255.25423.217.255.25565,534
21923.218.0.0/1623.218.0.1 to 23.218.255.25423.218.255.25565,534
22023.219.0.0/1623.219.0.1 to 23.219.255.25423.219.255.25565,534
22123.220.0.0/1623.220.0.1 to 23.220.255.25423.220.255.25565,534
22223.221.0.0/1623.221.0.1 to 23.221.255.25423.221.255.25565,534
22323.222.0.0/1623.222.0.1 to 23.222.255.25423.222.255.25565,534
22423.223.0.0/1623.223.0.1 to 23.223.255.25423.223.255.25565,534
22523.224.0.0/1623.224.0.1 to 23.224.255.25423.224.255.25565,534
22623.225.0.0/1623.225.0.1 to 23.225.255.25423.225.255.25565,534
22723.226.0.0/1623.226.0.1 to 23.226.255.25423.226.255.25565,534
22823.227.0.0/1623.227.0.1 to 23.227.255.25423.227.255.25565,534
22923.228.0.0/1623.228.0.1 to 23.228.255.25423.228.255.25565,534
23023.229.0.0/1623.229.0.1 to 23.229.255.25423.229.255.25565,534
23123.230.0.0/1623.230.0.1 to 23.230.255.25423.230.255.25565,534
23223.231.0.0/1623.231.0.1 to 23.231.255.25423.231.255.25565,534
23323.232.0.0/1623.232.0.1 to 23.232.255.25423.232.255.25565,534
23423.233.0.0/1623.233.0.1 to 23.233.255.25423.233.255.25565,534
23523.234.0.0/1623.234.0.1 to 23.234.255.25423.234.255.25565,534
23623.235.0.0/1623.235.0.1 to 23.235.255.25423.235.255.25565,534
23723.236.0.0/1623.236.0.1 to 23.236.255.25423.236.255.25565,534
23823.237.0.0/1623.237.0.1 to 23.237.255.25423.237.255.25565,534
23923.238.0.0/1623.238.0.1 to 23.238.255.25423.238.255.25565,534
24023.239.0.0/1623.239.0.1 to 23.239.255.25423.239.255.25565,534
24123.240.0.0/1623.240.0.1 to 23.240.255.25423.240.255.25565,534
24223.241.0.0/1623.241.0.1 to 23.241.255.25423.241.255.25565,534
24323.242.0.0/1623.242.0.1 to 23.242.255.25423.242.255.25565,534
24423.243.0.0/1623.243.0.1 to 23.243.255.25423.243.255.25565,534
24523.244.0.0/1623.244.0.1 to 23.244.255.25423.244.255.25565,534
24623.245.0.0/1623.245.0.1 to 23.245.255.25423.245.255.25565,534
24723.246.0.0/1623.246.0.1 to 23.246.255.25423.246.255.25565,534
24823.247.0.0/1623.247.0.1 to 23.247.255.25423.247.255.25565,534
24923.248.0.0/1623.248.0.1 to 23.248.255.25423.248.255.25565,534
25023.249.0.0/1623.249.0.1 to 23.249.255.25423.249.255.25565,534
25123.250.0.0/1623.250.0.1 to 23.250.255.25423.250.255.25565,534
25223.251.0.0/1623.251.0.1 to 23.251.255.25423.251.255.25565,534
25323.252.0.0/1623.252.0.1 to 23.252.255.25423.252.255.25565,534
25423.253.0.0/1623.253.0.1 to 23.253.255.25423.253.255.25565,534
25523.254.0.0/1623.254.0.1 to 23.254.255.25423.254.255.25565,534
25623.255.0.0/1623.255.0.1 to 23.255.255.25423.255.255.25565,534

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.