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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.

Network23.23.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
23.23.0.0
Broadcast address
23.23.255.255
First usable
23.23.0.1
Last usable
23.23.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
A (default /8)
As numbers
Hex 17170000 · Integer 387383296 to 387448831
Reverse DNS zone
23.23.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010111.00010111..00000000.0000000023.23.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network00010111.00010111..00000000.0000000023.23.0.0
Broadcast00010111.00010111..11111111.1111111123.23.255.255
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

23.23.0.0/16 makes 256 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.23.0.0/2423.23.0.1 to 23.23.0.25423.23.0.255254
223.23.1.0/2423.23.1.1 to 23.23.1.25423.23.1.255254
323.23.2.0/2423.23.2.1 to 23.23.2.25423.23.2.255254
423.23.3.0/2423.23.3.1 to 23.23.3.25423.23.3.255254
523.23.4.0/2423.23.4.1 to 23.23.4.25423.23.4.255254
623.23.5.0/2423.23.5.1 to 23.23.5.25423.23.5.255254
723.23.6.0/2423.23.6.1 to 23.23.6.25423.23.6.255254
823.23.7.0/2423.23.7.1 to 23.23.7.25423.23.7.255254
923.23.8.0/2423.23.8.1 to 23.23.8.25423.23.8.255254
1023.23.9.0/2423.23.9.1 to 23.23.9.25423.23.9.255254
1123.23.10.0/2423.23.10.1 to 23.23.10.25423.23.10.255254
1223.23.11.0/2423.23.11.1 to 23.23.11.25423.23.11.255254
1323.23.12.0/2423.23.12.1 to 23.23.12.25423.23.12.255254
1423.23.13.0/2423.23.13.1 to 23.23.13.25423.23.13.255254
1523.23.14.0/2423.23.14.1 to 23.23.14.25423.23.14.255254
1623.23.15.0/2423.23.15.1 to 23.23.15.25423.23.15.255254
1723.23.16.0/2423.23.16.1 to 23.23.16.25423.23.16.255254
1823.23.17.0/2423.23.17.1 to 23.23.17.25423.23.17.255254
1923.23.18.0/2423.23.18.1 to 23.23.18.25423.23.18.255254
2023.23.19.0/2423.23.19.1 to 23.23.19.25423.23.19.255254
2123.23.20.0/2423.23.20.1 to 23.23.20.25423.23.20.255254
2223.23.21.0/2423.23.21.1 to 23.23.21.25423.23.21.255254
2323.23.22.0/2423.23.22.1 to 23.23.22.25423.23.22.255254
2423.23.23.0/2423.23.23.1 to 23.23.23.25423.23.23.255254
2523.23.24.0/2423.23.24.1 to 23.23.24.25423.23.24.255254
2623.23.25.0/2423.23.25.1 to 23.23.25.25423.23.25.255254
2723.23.26.0/2423.23.26.1 to 23.23.26.25423.23.26.255254
2823.23.27.0/2423.23.27.1 to 23.23.27.25423.23.27.255254
2923.23.28.0/2423.23.28.1 to 23.23.28.25423.23.28.255254
3023.23.29.0/2423.23.29.1 to 23.23.29.25423.23.29.255254
3123.23.30.0/2423.23.30.1 to 23.23.30.25423.23.30.255254
3223.23.31.0/2423.23.31.1 to 23.23.31.25423.23.31.255254
3323.23.32.0/2423.23.32.1 to 23.23.32.25423.23.32.255254
3423.23.33.0/2423.23.33.1 to 23.23.33.25423.23.33.255254
3523.23.34.0/2423.23.34.1 to 23.23.34.25423.23.34.255254
3623.23.35.0/2423.23.35.1 to 23.23.35.25423.23.35.255254
3723.23.36.0/2423.23.36.1 to 23.23.36.25423.23.36.255254
3823.23.37.0/2423.23.37.1 to 23.23.37.25423.23.37.255254
3923.23.38.0/2423.23.38.1 to 23.23.38.25423.23.38.255254
4023.23.39.0/2423.23.39.1 to 23.23.39.25423.23.39.255254
4123.23.40.0/2423.23.40.1 to 23.23.40.25423.23.40.255254
4223.23.41.0/2423.23.41.1 to 23.23.41.25423.23.41.255254
4323.23.42.0/2423.23.42.1 to 23.23.42.25423.23.42.255254
4423.23.43.0/2423.23.43.1 to 23.23.43.25423.23.43.255254
4523.23.44.0/2423.23.44.1 to 23.23.44.25423.23.44.255254
4623.23.45.0/2423.23.45.1 to 23.23.45.25423.23.45.255254
4723.23.46.0/2423.23.46.1 to 23.23.46.25423.23.46.255254
4823.23.47.0/2423.23.47.1 to 23.23.47.25423.23.47.255254
4923.23.48.0/2423.23.48.1 to 23.23.48.25423.23.48.255254
5023.23.49.0/2423.23.49.1 to 23.23.49.25423.23.49.255254
5123.23.50.0/2423.23.50.1 to 23.23.50.25423.23.50.255254
5223.23.51.0/2423.23.51.1 to 23.23.51.25423.23.51.255254
5323.23.52.0/2423.23.52.1 to 23.23.52.25423.23.52.255254
5423.23.53.0/2423.23.53.1 to 23.23.53.25423.23.53.255254
5523.23.54.0/2423.23.54.1 to 23.23.54.25423.23.54.255254
5623.23.55.0/2423.23.55.1 to 23.23.55.25423.23.55.255254
5723.23.56.0/2423.23.56.1 to 23.23.56.25423.23.56.255254
5823.23.57.0/2423.23.57.1 to 23.23.57.25423.23.57.255254
5923.23.58.0/2423.23.58.1 to 23.23.58.25423.23.58.255254
6023.23.59.0/2423.23.59.1 to 23.23.59.25423.23.59.255254
6123.23.60.0/2423.23.60.1 to 23.23.60.25423.23.60.255254
6223.23.61.0/2423.23.61.1 to 23.23.61.25423.23.61.255254
6323.23.62.0/2423.23.62.1 to 23.23.62.25423.23.62.255254
6423.23.63.0/2423.23.63.1 to 23.23.63.25423.23.63.255254
6523.23.64.0/2423.23.64.1 to 23.23.64.25423.23.64.255254
6623.23.65.0/2423.23.65.1 to 23.23.65.25423.23.65.255254
6723.23.66.0/2423.23.66.1 to 23.23.66.25423.23.66.255254
6823.23.67.0/2423.23.67.1 to 23.23.67.25423.23.67.255254
6923.23.68.0/2423.23.68.1 to 23.23.68.25423.23.68.255254
7023.23.69.0/2423.23.69.1 to 23.23.69.25423.23.69.255254
7123.23.70.0/2423.23.70.1 to 23.23.70.25423.23.70.255254
7223.23.71.0/2423.23.71.1 to 23.23.71.25423.23.71.255254
7323.23.72.0/2423.23.72.1 to 23.23.72.25423.23.72.255254
7423.23.73.0/2423.23.73.1 to 23.23.73.25423.23.73.255254
7523.23.74.0/2423.23.74.1 to 23.23.74.25423.23.74.255254
7623.23.75.0/2423.23.75.1 to 23.23.75.25423.23.75.255254
7723.23.76.0/2423.23.76.1 to 23.23.76.25423.23.76.255254
7823.23.77.0/2423.23.77.1 to 23.23.77.25423.23.77.255254
7923.23.78.0/2423.23.78.1 to 23.23.78.25423.23.78.255254
8023.23.79.0/2423.23.79.1 to 23.23.79.25423.23.79.255254
8123.23.80.0/2423.23.80.1 to 23.23.80.25423.23.80.255254
8223.23.81.0/2423.23.81.1 to 23.23.81.25423.23.81.255254
8323.23.82.0/2423.23.82.1 to 23.23.82.25423.23.82.255254
8423.23.83.0/2423.23.83.1 to 23.23.83.25423.23.83.255254
8523.23.84.0/2423.23.84.1 to 23.23.84.25423.23.84.255254
8623.23.85.0/2423.23.85.1 to 23.23.85.25423.23.85.255254
8723.23.86.0/2423.23.86.1 to 23.23.86.25423.23.86.255254
8823.23.87.0/2423.23.87.1 to 23.23.87.25423.23.87.255254
8923.23.88.0/2423.23.88.1 to 23.23.88.25423.23.88.255254
9023.23.89.0/2423.23.89.1 to 23.23.89.25423.23.89.255254
9123.23.90.0/2423.23.90.1 to 23.23.90.25423.23.90.255254
9223.23.91.0/2423.23.91.1 to 23.23.91.25423.23.91.255254
9323.23.92.0/2423.23.92.1 to 23.23.92.25423.23.92.255254
9423.23.93.0/2423.23.93.1 to 23.23.93.25423.23.93.255254
9523.23.94.0/2423.23.94.1 to 23.23.94.25423.23.94.255254
9623.23.95.0/2423.23.95.1 to 23.23.95.25423.23.95.255254
9723.23.96.0/2423.23.96.1 to 23.23.96.25423.23.96.255254
9823.23.97.0/2423.23.97.1 to 23.23.97.25423.23.97.255254
9923.23.98.0/2423.23.98.1 to 23.23.98.25423.23.98.255254
10023.23.99.0/2423.23.99.1 to 23.23.99.25423.23.99.255254
10123.23.100.0/2423.23.100.1 to 23.23.100.25423.23.100.255254
10223.23.101.0/2423.23.101.1 to 23.23.101.25423.23.101.255254
10323.23.102.0/2423.23.102.1 to 23.23.102.25423.23.102.255254
10423.23.103.0/2423.23.103.1 to 23.23.103.25423.23.103.255254
10523.23.104.0/2423.23.104.1 to 23.23.104.25423.23.104.255254
10623.23.105.0/2423.23.105.1 to 23.23.105.25423.23.105.255254
10723.23.106.0/2423.23.106.1 to 23.23.106.25423.23.106.255254
10823.23.107.0/2423.23.107.1 to 23.23.107.25423.23.107.255254
10923.23.108.0/2423.23.108.1 to 23.23.108.25423.23.108.255254
11023.23.109.0/2423.23.109.1 to 23.23.109.25423.23.109.255254
11123.23.110.0/2423.23.110.1 to 23.23.110.25423.23.110.255254
11223.23.111.0/2423.23.111.1 to 23.23.111.25423.23.111.255254
11323.23.112.0/2423.23.112.1 to 23.23.112.25423.23.112.255254
11423.23.113.0/2423.23.113.1 to 23.23.113.25423.23.113.255254
11523.23.114.0/2423.23.114.1 to 23.23.114.25423.23.114.255254
11623.23.115.0/2423.23.115.1 to 23.23.115.25423.23.115.255254
11723.23.116.0/2423.23.116.1 to 23.23.116.25423.23.116.255254
11823.23.117.0/2423.23.117.1 to 23.23.117.25423.23.117.255254
11923.23.118.0/2423.23.118.1 to 23.23.118.25423.23.118.255254
12023.23.119.0/2423.23.119.1 to 23.23.119.25423.23.119.255254
12123.23.120.0/2423.23.120.1 to 23.23.120.25423.23.120.255254
12223.23.121.0/2423.23.121.1 to 23.23.121.25423.23.121.255254
12323.23.122.0/2423.23.122.1 to 23.23.122.25423.23.122.255254
12423.23.123.0/2423.23.123.1 to 23.23.123.25423.23.123.255254
12523.23.124.0/2423.23.124.1 to 23.23.124.25423.23.124.255254
12623.23.125.0/2423.23.125.1 to 23.23.125.25423.23.125.255254
12723.23.126.0/2423.23.126.1 to 23.23.126.25423.23.126.255254
12823.23.127.0/2423.23.127.1 to 23.23.127.25423.23.127.255254
12923.23.128.0/2423.23.128.1 to 23.23.128.25423.23.128.255254
13023.23.129.0/2423.23.129.1 to 23.23.129.25423.23.129.255254
13123.23.130.0/2423.23.130.1 to 23.23.130.25423.23.130.255254
13223.23.131.0/2423.23.131.1 to 23.23.131.25423.23.131.255254
13323.23.132.0/2423.23.132.1 to 23.23.132.25423.23.132.255254
13423.23.133.0/2423.23.133.1 to 23.23.133.25423.23.133.255254
13523.23.134.0/2423.23.134.1 to 23.23.134.25423.23.134.255254
13623.23.135.0/2423.23.135.1 to 23.23.135.25423.23.135.255254
13723.23.136.0/2423.23.136.1 to 23.23.136.25423.23.136.255254
13823.23.137.0/2423.23.137.1 to 23.23.137.25423.23.137.255254
13923.23.138.0/2423.23.138.1 to 23.23.138.25423.23.138.255254
14023.23.139.0/2423.23.139.1 to 23.23.139.25423.23.139.255254
14123.23.140.0/2423.23.140.1 to 23.23.140.25423.23.140.255254
14223.23.141.0/2423.23.141.1 to 23.23.141.25423.23.141.255254
14323.23.142.0/2423.23.142.1 to 23.23.142.25423.23.142.255254
14423.23.143.0/2423.23.143.1 to 23.23.143.25423.23.143.255254
14523.23.144.0/2423.23.144.1 to 23.23.144.25423.23.144.255254
14623.23.145.0/2423.23.145.1 to 23.23.145.25423.23.145.255254
14723.23.146.0/2423.23.146.1 to 23.23.146.25423.23.146.255254
14823.23.147.0/2423.23.147.1 to 23.23.147.25423.23.147.255254
14923.23.148.0/2423.23.148.1 to 23.23.148.25423.23.148.255254
15023.23.149.0/2423.23.149.1 to 23.23.149.25423.23.149.255254
15123.23.150.0/2423.23.150.1 to 23.23.150.25423.23.150.255254
15223.23.151.0/2423.23.151.1 to 23.23.151.25423.23.151.255254
15323.23.152.0/2423.23.152.1 to 23.23.152.25423.23.152.255254
15423.23.153.0/2423.23.153.1 to 23.23.153.25423.23.153.255254
15523.23.154.0/2423.23.154.1 to 23.23.154.25423.23.154.255254
15623.23.155.0/2423.23.155.1 to 23.23.155.25423.23.155.255254
15723.23.156.0/2423.23.156.1 to 23.23.156.25423.23.156.255254
15823.23.157.0/2423.23.157.1 to 23.23.157.25423.23.157.255254
15923.23.158.0/2423.23.158.1 to 23.23.158.25423.23.158.255254
16023.23.159.0/2423.23.159.1 to 23.23.159.25423.23.159.255254
16123.23.160.0/2423.23.160.1 to 23.23.160.25423.23.160.255254
16223.23.161.0/2423.23.161.1 to 23.23.161.25423.23.161.255254
16323.23.162.0/2423.23.162.1 to 23.23.162.25423.23.162.255254
16423.23.163.0/2423.23.163.1 to 23.23.163.25423.23.163.255254
16523.23.164.0/2423.23.164.1 to 23.23.164.25423.23.164.255254
16623.23.165.0/2423.23.165.1 to 23.23.165.25423.23.165.255254
16723.23.166.0/2423.23.166.1 to 23.23.166.25423.23.166.255254
16823.23.167.0/2423.23.167.1 to 23.23.167.25423.23.167.255254
16923.23.168.0/2423.23.168.1 to 23.23.168.25423.23.168.255254
17023.23.169.0/2423.23.169.1 to 23.23.169.25423.23.169.255254
17123.23.170.0/2423.23.170.1 to 23.23.170.25423.23.170.255254
17223.23.171.0/2423.23.171.1 to 23.23.171.25423.23.171.255254
17323.23.172.0/2423.23.172.1 to 23.23.172.25423.23.172.255254
17423.23.173.0/2423.23.173.1 to 23.23.173.25423.23.173.255254
17523.23.174.0/2423.23.174.1 to 23.23.174.25423.23.174.255254
17623.23.175.0/2423.23.175.1 to 23.23.175.25423.23.175.255254
17723.23.176.0/2423.23.176.1 to 23.23.176.25423.23.176.255254
17823.23.177.0/2423.23.177.1 to 23.23.177.25423.23.177.255254
17923.23.178.0/2423.23.178.1 to 23.23.178.25423.23.178.255254
18023.23.179.0/2423.23.179.1 to 23.23.179.25423.23.179.255254
18123.23.180.0/2423.23.180.1 to 23.23.180.25423.23.180.255254
18223.23.181.0/2423.23.181.1 to 23.23.181.25423.23.181.255254
18323.23.182.0/2423.23.182.1 to 23.23.182.25423.23.182.255254
18423.23.183.0/2423.23.183.1 to 23.23.183.25423.23.183.255254
18523.23.184.0/2423.23.184.1 to 23.23.184.25423.23.184.255254
18623.23.185.0/2423.23.185.1 to 23.23.185.25423.23.185.255254
18723.23.186.0/2423.23.186.1 to 23.23.186.25423.23.186.255254
18823.23.187.0/2423.23.187.1 to 23.23.187.25423.23.187.255254
18923.23.188.0/2423.23.188.1 to 23.23.188.25423.23.188.255254
19023.23.189.0/2423.23.189.1 to 23.23.189.25423.23.189.255254
19123.23.190.0/2423.23.190.1 to 23.23.190.25423.23.190.255254
19223.23.191.0/2423.23.191.1 to 23.23.191.25423.23.191.255254
19323.23.192.0/2423.23.192.1 to 23.23.192.25423.23.192.255254
19423.23.193.0/2423.23.193.1 to 23.23.193.25423.23.193.255254
19523.23.194.0/2423.23.194.1 to 23.23.194.25423.23.194.255254
19623.23.195.0/2423.23.195.1 to 23.23.195.25423.23.195.255254
19723.23.196.0/2423.23.196.1 to 23.23.196.25423.23.196.255254
19823.23.197.0/2423.23.197.1 to 23.23.197.25423.23.197.255254
19923.23.198.0/2423.23.198.1 to 23.23.198.25423.23.198.255254
20023.23.199.0/2423.23.199.1 to 23.23.199.25423.23.199.255254
20123.23.200.0/2423.23.200.1 to 23.23.200.25423.23.200.255254
20223.23.201.0/2423.23.201.1 to 23.23.201.25423.23.201.255254
20323.23.202.0/2423.23.202.1 to 23.23.202.25423.23.202.255254
20423.23.203.0/2423.23.203.1 to 23.23.203.25423.23.203.255254
20523.23.204.0/2423.23.204.1 to 23.23.204.25423.23.204.255254
20623.23.205.0/2423.23.205.1 to 23.23.205.25423.23.205.255254
20723.23.206.0/2423.23.206.1 to 23.23.206.25423.23.206.255254
20823.23.207.0/2423.23.207.1 to 23.23.207.25423.23.207.255254
20923.23.208.0/2423.23.208.1 to 23.23.208.25423.23.208.255254
21023.23.209.0/2423.23.209.1 to 23.23.209.25423.23.209.255254
21123.23.210.0/2423.23.210.1 to 23.23.210.25423.23.210.255254
21223.23.211.0/2423.23.211.1 to 23.23.211.25423.23.211.255254
21323.23.212.0/2423.23.212.1 to 23.23.212.25423.23.212.255254
21423.23.213.0/2423.23.213.1 to 23.23.213.25423.23.213.255254
21523.23.214.0/2423.23.214.1 to 23.23.214.25423.23.214.255254
21623.23.215.0/2423.23.215.1 to 23.23.215.25423.23.215.255254
21723.23.216.0/2423.23.216.1 to 23.23.216.25423.23.216.255254
21823.23.217.0/2423.23.217.1 to 23.23.217.25423.23.217.255254
21923.23.218.0/2423.23.218.1 to 23.23.218.25423.23.218.255254
22023.23.219.0/2423.23.219.1 to 23.23.219.25423.23.219.255254
22123.23.220.0/2423.23.220.1 to 23.23.220.25423.23.220.255254
22223.23.221.0/2423.23.221.1 to 23.23.221.25423.23.221.255254
22323.23.222.0/2423.23.222.1 to 23.23.222.25423.23.222.255254
22423.23.223.0/2423.23.223.1 to 23.23.223.25423.23.223.255254
22523.23.224.0/2423.23.224.1 to 23.23.224.25423.23.224.255254
22623.23.225.0/2423.23.225.1 to 23.23.225.25423.23.225.255254
22723.23.226.0/2423.23.226.1 to 23.23.226.25423.23.226.255254
22823.23.227.0/2423.23.227.1 to 23.23.227.25423.23.227.255254
22923.23.228.0/2423.23.228.1 to 23.23.228.25423.23.228.255254
23023.23.229.0/2423.23.229.1 to 23.23.229.25423.23.229.255254
23123.23.230.0/2423.23.230.1 to 23.23.230.25423.23.230.255254
23223.23.231.0/2423.23.231.1 to 23.23.231.25423.23.231.255254
23323.23.232.0/2423.23.232.1 to 23.23.232.25423.23.232.255254
23423.23.233.0/2423.23.233.1 to 23.23.233.25423.23.233.255254
23523.23.234.0/2423.23.234.1 to 23.23.234.25423.23.234.255254
23623.23.235.0/2423.23.235.1 to 23.23.235.25423.23.235.255254
23723.23.236.0/2423.23.236.1 to 23.23.236.25423.23.236.255254
23823.23.237.0/2423.23.237.1 to 23.23.237.25423.23.237.255254
23923.23.238.0/2423.23.238.1 to 23.23.238.25423.23.238.255254
24023.23.239.0/2423.23.239.1 to 23.23.239.25423.23.239.255254
24123.23.240.0/2423.23.240.1 to 23.23.240.25423.23.240.255254
24223.23.241.0/2423.23.241.1 to 23.23.241.25423.23.241.255254
24323.23.242.0/2423.23.242.1 to 23.23.242.25423.23.242.255254
24423.23.243.0/2423.23.243.1 to 23.23.243.25423.23.243.255254
24523.23.244.0/2423.23.244.1 to 23.23.244.25423.23.244.255254
24623.23.245.0/2423.23.245.1 to 23.23.245.25423.23.245.255254
24723.23.246.0/2423.23.246.1 to 23.23.246.25423.23.246.255254
24823.23.247.0/2423.23.247.1 to 23.23.247.25423.23.247.255254
24923.23.248.0/2423.23.248.1 to 23.23.248.25423.23.248.255254
25023.23.249.0/2423.23.249.1 to 23.23.249.25423.23.249.255254
25123.23.250.0/2423.23.250.1 to 23.23.250.25423.23.250.255254
25223.23.251.0/2423.23.251.1 to 23.23.251.25423.23.251.255254
25323.23.252.0/2423.23.252.1 to 23.23.252.25423.23.252.255254
25423.23.253.0/2423.23.253.1 to 23.23.253.25423.23.253.255254
25523.23.254.0/2423.23.254.1 to 23.23.254.25423.23.254.255254
25623.23.255.0/2423.23.255.1 to 23.23.255.25423.23.255.255254

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.