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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.

Network81.0.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
81.0.0.0
Broadcast address
81.7.255.255
First usable
81.0.0.1
Last usable
81.7.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
A (default /8)
As numbers
Hex 51000000 · Integer 1358954496 to 1359478783
Reverse DNS zones
0.81.in-addr.arpa
1.81.in-addr.arpa
2.81.in-addr.arpa
3.81.in-addr.arpa
4.81.in-addr.arpa
5.81.in-addr.arpa
6.81.in-addr.arpa
7.81.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010001.00000000.00000000.0000000081.0.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01010001.00000000.00000000.0000000081.0.0.0
Broadcast01010001.00000111.11111111.1111111181.7.255.255
Split into smaller subnets/23
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

81.0.0.0/13 makes 1,024 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
181.0.0.0/2381.0.0.1 to 81.0.1.25481.0.1.255510
281.0.2.0/2381.0.2.1 to 81.0.3.25481.0.3.255510
381.0.4.0/2381.0.4.1 to 81.0.5.25481.0.5.255510
481.0.6.0/2381.0.6.1 to 81.0.7.25481.0.7.255510
581.0.8.0/2381.0.8.1 to 81.0.9.25481.0.9.255510
681.0.10.0/2381.0.10.1 to 81.0.11.25481.0.11.255510
781.0.12.0/2381.0.12.1 to 81.0.13.25481.0.13.255510
881.0.14.0/2381.0.14.1 to 81.0.15.25481.0.15.255510
981.0.16.0/2381.0.16.1 to 81.0.17.25481.0.17.255510
1081.0.18.0/2381.0.18.1 to 81.0.19.25481.0.19.255510
1181.0.20.0/2381.0.20.1 to 81.0.21.25481.0.21.255510
1281.0.22.0/2381.0.22.1 to 81.0.23.25481.0.23.255510
1381.0.24.0/2381.0.24.1 to 81.0.25.25481.0.25.255510
1481.0.26.0/2381.0.26.1 to 81.0.27.25481.0.27.255510
1581.0.28.0/2381.0.28.1 to 81.0.29.25481.0.29.255510
1681.0.30.0/2381.0.30.1 to 81.0.31.25481.0.31.255510
1781.0.32.0/2381.0.32.1 to 81.0.33.25481.0.33.255510
1881.0.34.0/2381.0.34.1 to 81.0.35.25481.0.35.255510
1981.0.36.0/2381.0.36.1 to 81.0.37.25481.0.37.255510
2081.0.38.0/2381.0.38.1 to 81.0.39.25481.0.39.255510
2181.0.40.0/2381.0.40.1 to 81.0.41.25481.0.41.255510
2281.0.42.0/2381.0.42.1 to 81.0.43.25481.0.43.255510
2381.0.44.0/2381.0.44.1 to 81.0.45.25481.0.45.255510
2481.0.46.0/2381.0.46.1 to 81.0.47.25481.0.47.255510
2581.0.48.0/2381.0.48.1 to 81.0.49.25481.0.49.255510
2681.0.50.0/2381.0.50.1 to 81.0.51.25481.0.51.255510
2781.0.52.0/2381.0.52.1 to 81.0.53.25481.0.53.255510
2881.0.54.0/2381.0.54.1 to 81.0.55.25481.0.55.255510
2981.0.56.0/2381.0.56.1 to 81.0.57.25481.0.57.255510
3081.0.58.0/2381.0.58.1 to 81.0.59.25481.0.59.255510
3181.0.60.0/2381.0.60.1 to 81.0.61.25481.0.61.255510
3281.0.62.0/2381.0.62.1 to 81.0.63.25481.0.63.255510
3381.0.64.0/2381.0.64.1 to 81.0.65.25481.0.65.255510
3481.0.66.0/2381.0.66.1 to 81.0.67.25481.0.67.255510
3581.0.68.0/2381.0.68.1 to 81.0.69.25481.0.69.255510
3681.0.70.0/2381.0.70.1 to 81.0.71.25481.0.71.255510
3781.0.72.0/2381.0.72.1 to 81.0.73.25481.0.73.255510
3881.0.74.0/2381.0.74.1 to 81.0.75.25481.0.75.255510
3981.0.76.0/2381.0.76.1 to 81.0.77.25481.0.77.255510
4081.0.78.0/2381.0.78.1 to 81.0.79.25481.0.79.255510
4181.0.80.0/2381.0.80.1 to 81.0.81.25481.0.81.255510
4281.0.82.0/2381.0.82.1 to 81.0.83.25481.0.83.255510
4381.0.84.0/2381.0.84.1 to 81.0.85.25481.0.85.255510
4481.0.86.0/2381.0.86.1 to 81.0.87.25481.0.87.255510
4581.0.88.0/2381.0.88.1 to 81.0.89.25481.0.89.255510
4681.0.90.0/2381.0.90.1 to 81.0.91.25481.0.91.255510
4781.0.92.0/2381.0.92.1 to 81.0.93.25481.0.93.255510
4881.0.94.0/2381.0.94.1 to 81.0.95.25481.0.95.255510
4981.0.96.0/2381.0.96.1 to 81.0.97.25481.0.97.255510
5081.0.98.0/2381.0.98.1 to 81.0.99.25481.0.99.255510
5181.0.100.0/2381.0.100.1 to 81.0.101.25481.0.101.255510
5281.0.102.0/2381.0.102.1 to 81.0.103.25481.0.103.255510
5381.0.104.0/2381.0.104.1 to 81.0.105.25481.0.105.255510
5481.0.106.0/2381.0.106.1 to 81.0.107.25481.0.107.255510
5581.0.108.0/2381.0.108.1 to 81.0.109.25481.0.109.255510
5681.0.110.0/2381.0.110.1 to 81.0.111.25481.0.111.255510
5781.0.112.0/2381.0.112.1 to 81.0.113.25481.0.113.255510
5881.0.114.0/2381.0.114.1 to 81.0.115.25481.0.115.255510
5981.0.116.0/2381.0.116.1 to 81.0.117.25481.0.117.255510
6081.0.118.0/2381.0.118.1 to 81.0.119.25481.0.119.255510
6181.0.120.0/2381.0.120.1 to 81.0.121.25481.0.121.255510
6281.0.122.0/2381.0.122.1 to 81.0.123.25481.0.123.255510
6381.0.124.0/2381.0.124.1 to 81.0.125.25481.0.125.255510
6481.0.126.0/2381.0.126.1 to 81.0.127.25481.0.127.255510
6581.0.128.0/2381.0.128.1 to 81.0.129.25481.0.129.255510
6681.0.130.0/2381.0.130.1 to 81.0.131.25481.0.131.255510
6781.0.132.0/2381.0.132.1 to 81.0.133.25481.0.133.255510
6881.0.134.0/2381.0.134.1 to 81.0.135.25481.0.135.255510
6981.0.136.0/2381.0.136.1 to 81.0.137.25481.0.137.255510
7081.0.138.0/2381.0.138.1 to 81.0.139.25481.0.139.255510
7181.0.140.0/2381.0.140.1 to 81.0.141.25481.0.141.255510
7281.0.142.0/2381.0.142.1 to 81.0.143.25481.0.143.255510
7381.0.144.0/2381.0.144.1 to 81.0.145.25481.0.145.255510
7481.0.146.0/2381.0.146.1 to 81.0.147.25481.0.147.255510
7581.0.148.0/2381.0.148.1 to 81.0.149.25481.0.149.255510
7681.0.150.0/2381.0.150.1 to 81.0.151.25481.0.151.255510
7781.0.152.0/2381.0.152.1 to 81.0.153.25481.0.153.255510
7881.0.154.0/2381.0.154.1 to 81.0.155.25481.0.155.255510
7981.0.156.0/2381.0.156.1 to 81.0.157.25481.0.157.255510
8081.0.158.0/2381.0.158.1 to 81.0.159.25481.0.159.255510
8181.0.160.0/2381.0.160.1 to 81.0.161.25481.0.161.255510
8281.0.162.0/2381.0.162.1 to 81.0.163.25481.0.163.255510
8381.0.164.0/2381.0.164.1 to 81.0.165.25481.0.165.255510
8481.0.166.0/2381.0.166.1 to 81.0.167.25481.0.167.255510
8581.0.168.0/2381.0.168.1 to 81.0.169.25481.0.169.255510
8681.0.170.0/2381.0.170.1 to 81.0.171.25481.0.171.255510
8781.0.172.0/2381.0.172.1 to 81.0.173.25481.0.173.255510
8881.0.174.0/2381.0.174.1 to 81.0.175.25481.0.175.255510
8981.0.176.0/2381.0.176.1 to 81.0.177.25481.0.177.255510
9081.0.178.0/2381.0.178.1 to 81.0.179.25481.0.179.255510
9181.0.180.0/2381.0.180.1 to 81.0.181.25481.0.181.255510
9281.0.182.0/2381.0.182.1 to 81.0.183.25481.0.183.255510
9381.0.184.0/2381.0.184.1 to 81.0.185.25481.0.185.255510
9481.0.186.0/2381.0.186.1 to 81.0.187.25481.0.187.255510
9581.0.188.0/2381.0.188.1 to 81.0.189.25481.0.189.255510
9681.0.190.0/2381.0.190.1 to 81.0.191.25481.0.191.255510
9781.0.192.0/2381.0.192.1 to 81.0.193.25481.0.193.255510
9881.0.194.0/2381.0.194.1 to 81.0.195.25481.0.195.255510
9981.0.196.0/2381.0.196.1 to 81.0.197.25481.0.197.255510
10081.0.198.0/2381.0.198.1 to 81.0.199.25481.0.199.255510
10181.0.200.0/2381.0.200.1 to 81.0.201.25481.0.201.255510
10281.0.202.0/2381.0.202.1 to 81.0.203.25481.0.203.255510
10381.0.204.0/2381.0.204.1 to 81.0.205.25481.0.205.255510
10481.0.206.0/2381.0.206.1 to 81.0.207.25481.0.207.255510
10581.0.208.0/2381.0.208.1 to 81.0.209.25481.0.209.255510
10681.0.210.0/2381.0.210.1 to 81.0.211.25481.0.211.255510
10781.0.212.0/2381.0.212.1 to 81.0.213.25481.0.213.255510
10881.0.214.0/2381.0.214.1 to 81.0.215.25481.0.215.255510
10981.0.216.0/2381.0.216.1 to 81.0.217.25481.0.217.255510
11081.0.218.0/2381.0.218.1 to 81.0.219.25481.0.219.255510
11181.0.220.0/2381.0.220.1 to 81.0.221.25481.0.221.255510
11281.0.222.0/2381.0.222.1 to 81.0.223.25481.0.223.255510
11381.0.224.0/2381.0.224.1 to 81.0.225.25481.0.225.255510
11481.0.226.0/2381.0.226.1 to 81.0.227.25481.0.227.255510
11581.0.228.0/2381.0.228.1 to 81.0.229.25481.0.229.255510
11681.0.230.0/2381.0.230.1 to 81.0.231.25481.0.231.255510
11781.0.232.0/2381.0.232.1 to 81.0.233.25481.0.233.255510
11881.0.234.0/2381.0.234.1 to 81.0.235.25481.0.235.255510
11981.0.236.0/2381.0.236.1 to 81.0.237.25481.0.237.255510
12081.0.238.0/2381.0.238.1 to 81.0.239.25481.0.239.255510
12181.0.240.0/2381.0.240.1 to 81.0.241.25481.0.241.255510
12281.0.242.0/2381.0.242.1 to 81.0.243.25481.0.243.255510
12381.0.244.0/2381.0.244.1 to 81.0.245.25481.0.245.255510
12481.0.246.0/2381.0.246.1 to 81.0.247.25481.0.247.255510
12581.0.248.0/2381.0.248.1 to 81.0.249.25481.0.249.255510
12681.0.250.0/2381.0.250.1 to 81.0.251.25481.0.251.255510
12781.0.252.0/2381.0.252.1 to 81.0.253.25481.0.253.255510
12881.0.254.0/2381.0.254.1 to 81.0.255.25481.0.255.255510
12981.1.0.0/2381.1.0.1 to 81.1.1.25481.1.1.255510
13081.1.2.0/2381.1.2.1 to 81.1.3.25481.1.3.255510
13181.1.4.0/2381.1.4.1 to 81.1.5.25481.1.5.255510
13281.1.6.0/2381.1.6.1 to 81.1.7.25481.1.7.255510
13381.1.8.0/2381.1.8.1 to 81.1.9.25481.1.9.255510
13481.1.10.0/2381.1.10.1 to 81.1.11.25481.1.11.255510
13581.1.12.0/2381.1.12.1 to 81.1.13.25481.1.13.255510
13681.1.14.0/2381.1.14.1 to 81.1.15.25481.1.15.255510
13781.1.16.0/2381.1.16.1 to 81.1.17.25481.1.17.255510
13881.1.18.0/2381.1.18.1 to 81.1.19.25481.1.19.255510
13981.1.20.0/2381.1.20.1 to 81.1.21.25481.1.21.255510
14081.1.22.0/2381.1.22.1 to 81.1.23.25481.1.23.255510
14181.1.24.0/2381.1.24.1 to 81.1.25.25481.1.25.255510
14281.1.26.0/2381.1.26.1 to 81.1.27.25481.1.27.255510
14381.1.28.0/2381.1.28.1 to 81.1.29.25481.1.29.255510
14481.1.30.0/2381.1.30.1 to 81.1.31.25481.1.31.255510
14581.1.32.0/2381.1.32.1 to 81.1.33.25481.1.33.255510
14681.1.34.0/2381.1.34.1 to 81.1.35.25481.1.35.255510
14781.1.36.0/2381.1.36.1 to 81.1.37.25481.1.37.255510
14881.1.38.0/2381.1.38.1 to 81.1.39.25481.1.39.255510
14981.1.40.0/2381.1.40.1 to 81.1.41.25481.1.41.255510
15081.1.42.0/2381.1.42.1 to 81.1.43.25481.1.43.255510
15181.1.44.0/2381.1.44.1 to 81.1.45.25481.1.45.255510
15281.1.46.0/2381.1.46.1 to 81.1.47.25481.1.47.255510
15381.1.48.0/2381.1.48.1 to 81.1.49.25481.1.49.255510
15481.1.50.0/2381.1.50.1 to 81.1.51.25481.1.51.255510
15581.1.52.0/2381.1.52.1 to 81.1.53.25481.1.53.255510
15681.1.54.0/2381.1.54.1 to 81.1.55.25481.1.55.255510
15781.1.56.0/2381.1.56.1 to 81.1.57.25481.1.57.255510
15881.1.58.0/2381.1.58.1 to 81.1.59.25481.1.59.255510
15981.1.60.0/2381.1.60.1 to 81.1.61.25481.1.61.255510
16081.1.62.0/2381.1.62.1 to 81.1.63.25481.1.63.255510
16181.1.64.0/2381.1.64.1 to 81.1.65.25481.1.65.255510
16281.1.66.0/2381.1.66.1 to 81.1.67.25481.1.67.255510
16381.1.68.0/2381.1.68.1 to 81.1.69.25481.1.69.255510
16481.1.70.0/2381.1.70.1 to 81.1.71.25481.1.71.255510
16581.1.72.0/2381.1.72.1 to 81.1.73.25481.1.73.255510
16681.1.74.0/2381.1.74.1 to 81.1.75.25481.1.75.255510
16781.1.76.0/2381.1.76.1 to 81.1.77.25481.1.77.255510
16881.1.78.0/2381.1.78.1 to 81.1.79.25481.1.79.255510
16981.1.80.0/2381.1.80.1 to 81.1.81.25481.1.81.255510
17081.1.82.0/2381.1.82.1 to 81.1.83.25481.1.83.255510
17181.1.84.0/2381.1.84.1 to 81.1.85.25481.1.85.255510
17281.1.86.0/2381.1.86.1 to 81.1.87.25481.1.87.255510
17381.1.88.0/2381.1.88.1 to 81.1.89.25481.1.89.255510
17481.1.90.0/2381.1.90.1 to 81.1.91.25481.1.91.255510
17581.1.92.0/2381.1.92.1 to 81.1.93.25481.1.93.255510
17681.1.94.0/2381.1.94.1 to 81.1.95.25481.1.95.255510
17781.1.96.0/2381.1.96.1 to 81.1.97.25481.1.97.255510
17881.1.98.0/2381.1.98.1 to 81.1.99.25481.1.99.255510
17981.1.100.0/2381.1.100.1 to 81.1.101.25481.1.101.255510
18081.1.102.0/2381.1.102.1 to 81.1.103.25481.1.103.255510
18181.1.104.0/2381.1.104.1 to 81.1.105.25481.1.105.255510
18281.1.106.0/2381.1.106.1 to 81.1.107.25481.1.107.255510
18381.1.108.0/2381.1.108.1 to 81.1.109.25481.1.109.255510
18481.1.110.0/2381.1.110.1 to 81.1.111.25481.1.111.255510
18581.1.112.0/2381.1.112.1 to 81.1.113.25481.1.113.255510
18681.1.114.0/2381.1.114.1 to 81.1.115.25481.1.115.255510
18781.1.116.0/2381.1.116.1 to 81.1.117.25481.1.117.255510
18881.1.118.0/2381.1.118.1 to 81.1.119.25481.1.119.255510
18981.1.120.0/2381.1.120.1 to 81.1.121.25481.1.121.255510
19081.1.122.0/2381.1.122.1 to 81.1.123.25481.1.123.255510
19181.1.124.0/2381.1.124.1 to 81.1.125.25481.1.125.255510
19281.1.126.0/2381.1.126.1 to 81.1.127.25481.1.127.255510
19381.1.128.0/2381.1.128.1 to 81.1.129.25481.1.129.255510
19481.1.130.0/2381.1.130.1 to 81.1.131.25481.1.131.255510
19581.1.132.0/2381.1.132.1 to 81.1.133.25481.1.133.255510
19681.1.134.0/2381.1.134.1 to 81.1.135.25481.1.135.255510
19781.1.136.0/2381.1.136.1 to 81.1.137.25481.1.137.255510
19881.1.138.0/2381.1.138.1 to 81.1.139.25481.1.139.255510
19981.1.140.0/2381.1.140.1 to 81.1.141.25481.1.141.255510
20081.1.142.0/2381.1.142.1 to 81.1.143.25481.1.143.255510
20181.1.144.0/2381.1.144.1 to 81.1.145.25481.1.145.255510
20281.1.146.0/2381.1.146.1 to 81.1.147.25481.1.147.255510
20381.1.148.0/2381.1.148.1 to 81.1.149.25481.1.149.255510
20481.1.150.0/2381.1.150.1 to 81.1.151.25481.1.151.255510
20581.1.152.0/2381.1.152.1 to 81.1.153.25481.1.153.255510
20681.1.154.0/2381.1.154.1 to 81.1.155.25481.1.155.255510
20781.1.156.0/2381.1.156.1 to 81.1.157.25481.1.157.255510
20881.1.158.0/2381.1.158.1 to 81.1.159.25481.1.159.255510
20981.1.160.0/2381.1.160.1 to 81.1.161.25481.1.161.255510
21081.1.162.0/2381.1.162.1 to 81.1.163.25481.1.163.255510
21181.1.164.0/2381.1.164.1 to 81.1.165.25481.1.165.255510
21281.1.166.0/2381.1.166.1 to 81.1.167.25481.1.167.255510
21381.1.168.0/2381.1.168.1 to 81.1.169.25481.1.169.255510
21481.1.170.0/2381.1.170.1 to 81.1.171.25481.1.171.255510
21581.1.172.0/2381.1.172.1 to 81.1.173.25481.1.173.255510
21681.1.174.0/2381.1.174.1 to 81.1.175.25481.1.175.255510
21781.1.176.0/2381.1.176.1 to 81.1.177.25481.1.177.255510
21881.1.178.0/2381.1.178.1 to 81.1.179.25481.1.179.255510
21981.1.180.0/2381.1.180.1 to 81.1.181.25481.1.181.255510
22081.1.182.0/2381.1.182.1 to 81.1.183.25481.1.183.255510
22181.1.184.0/2381.1.184.1 to 81.1.185.25481.1.185.255510
22281.1.186.0/2381.1.186.1 to 81.1.187.25481.1.187.255510
22381.1.188.0/2381.1.188.1 to 81.1.189.25481.1.189.255510
22481.1.190.0/2381.1.190.1 to 81.1.191.25481.1.191.255510
22581.1.192.0/2381.1.192.1 to 81.1.193.25481.1.193.255510
22681.1.194.0/2381.1.194.1 to 81.1.195.25481.1.195.255510
22781.1.196.0/2381.1.196.1 to 81.1.197.25481.1.197.255510
22881.1.198.0/2381.1.198.1 to 81.1.199.25481.1.199.255510
22981.1.200.0/2381.1.200.1 to 81.1.201.25481.1.201.255510
23081.1.202.0/2381.1.202.1 to 81.1.203.25481.1.203.255510
23181.1.204.0/2381.1.204.1 to 81.1.205.25481.1.205.255510
23281.1.206.0/2381.1.206.1 to 81.1.207.25481.1.207.255510
23381.1.208.0/2381.1.208.1 to 81.1.209.25481.1.209.255510
23481.1.210.0/2381.1.210.1 to 81.1.211.25481.1.211.255510
23581.1.212.0/2381.1.212.1 to 81.1.213.25481.1.213.255510
23681.1.214.0/2381.1.214.1 to 81.1.215.25481.1.215.255510
23781.1.216.0/2381.1.216.1 to 81.1.217.25481.1.217.255510
23881.1.218.0/2381.1.218.1 to 81.1.219.25481.1.219.255510
23981.1.220.0/2381.1.220.1 to 81.1.221.25481.1.221.255510
24081.1.222.0/2381.1.222.1 to 81.1.223.25481.1.223.255510
24181.1.224.0/2381.1.224.1 to 81.1.225.25481.1.225.255510
24281.1.226.0/2381.1.226.1 to 81.1.227.25481.1.227.255510
24381.1.228.0/2381.1.228.1 to 81.1.229.25481.1.229.255510
24481.1.230.0/2381.1.230.1 to 81.1.231.25481.1.231.255510
24581.1.232.0/2381.1.232.1 to 81.1.233.25481.1.233.255510
24681.1.234.0/2381.1.234.1 to 81.1.235.25481.1.235.255510
24781.1.236.0/2381.1.236.1 to 81.1.237.25481.1.237.255510
24881.1.238.0/2381.1.238.1 to 81.1.239.25481.1.239.255510
24981.1.240.0/2381.1.240.1 to 81.1.241.25481.1.241.255510
25081.1.242.0/2381.1.242.1 to 81.1.243.25481.1.243.255510
25181.1.244.0/2381.1.244.1 to 81.1.245.25481.1.245.255510
25281.1.246.0/2381.1.246.1 to 81.1.247.25481.1.247.255510
25381.1.248.0/2381.1.248.1 to 81.1.249.25481.1.249.255510
25481.1.250.0/2381.1.250.1 to 81.1.251.25481.1.251.255510
25581.1.252.0/2381.1.252.1 to 81.1.253.25481.1.253.255510
25681.1.254.0/2381.1.254.1 to 81.1.255.25481.1.255.255510

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.