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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.

Network10.242.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
10.242.0.0
Broadcast address
10.243.255.255
First usable
10.242.0.1
Last usable
10.243.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Private (RFC 1918) 10.0.0.0/8
Office and home networks; not routed on the internet
Old class
A (default /8)
As numbers
Hex 0AF20000 · Integer 183631872 to 183762943
Reverse DNS zones
242.10.in-addr.arpa
243.10.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001010.11110010.00000000.0000000010.242.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00001010.11110010.00000000.0000000010.242.0.0
Broadcast00001010.11110011.11111111.1111111110.243.255.255
Split into smaller subnets/23
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

10.242.0.0/15 makes 256 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
110.242.0.0/2310.242.0.1 to 10.242.1.25410.242.1.255510
210.242.2.0/2310.242.2.1 to 10.242.3.25410.242.3.255510
310.242.4.0/2310.242.4.1 to 10.242.5.25410.242.5.255510
410.242.6.0/2310.242.6.1 to 10.242.7.25410.242.7.255510
510.242.8.0/2310.242.8.1 to 10.242.9.25410.242.9.255510
610.242.10.0/2310.242.10.1 to 10.242.11.25410.242.11.255510
710.242.12.0/2310.242.12.1 to 10.242.13.25410.242.13.255510
810.242.14.0/2310.242.14.1 to 10.242.15.25410.242.15.255510
910.242.16.0/2310.242.16.1 to 10.242.17.25410.242.17.255510
1010.242.18.0/2310.242.18.1 to 10.242.19.25410.242.19.255510
1110.242.20.0/2310.242.20.1 to 10.242.21.25410.242.21.255510
1210.242.22.0/2310.242.22.1 to 10.242.23.25410.242.23.255510
1310.242.24.0/2310.242.24.1 to 10.242.25.25410.242.25.255510
1410.242.26.0/2310.242.26.1 to 10.242.27.25410.242.27.255510
1510.242.28.0/2310.242.28.1 to 10.242.29.25410.242.29.255510
1610.242.30.0/2310.242.30.1 to 10.242.31.25410.242.31.255510
1710.242.32.0/2310.242.32.1 to 10.242.33.25410.242.33.255510
1810.242.34.0/2310.242.34.1 to 10.242.35.25410.242.35.255510
1910.242.36.0/2310.242.36.1 to 10.242.37.25410.242.37.255510
2010.242.38.0/2310.242.38.1 to 10.242.39.25410.242.39.255510
2110.242.40.0/2310.242.40.1 to 10.242.41.25410.242.41.255510
2210.242.42.0/2310.242.42.1 to 10.242.43.25410.242.43.255510
2310.242.44.0/2310.242.44.1 to 10.242.45.25410.242.45.255510
2410.242.46.0/2310.242.46.1 to 10.242.47.25410.242.47.255510
2510.242.48.0/2310.242.48.1 to 10.242.49.25410.242.49.255510
2610.242.50.0/2310.242.50.1 to 10.242.51.25410.242.51.255510
2710.242.52.0/2310.242.52.1 to 10.242.53.25410.242.53.255510
2810.242.54.0/2310.242.54.1 to 10.242.55.25410.242.55.255510
2910.242.56.0/2310.242.56.1 to 10.242.57.25410.242.57.255510
3010.242.58.0/2310.242.58.1 to 10.242.59.25410.242.59.255510
3110.242.60.0/2310.242.60.1 to 10.242.61.25410.242.61.255510
3210.242.62.0/2310.242.62.1 to 10.242.63.25410.242.63.255510
3310.242.64.0/2310.242.64.1 to 10.242.65.25410.242.65.255510
3410.242.66.0/2310.242.66.1 to 10.242.67.25410.242.67.255510
3510.242.68.0/2310.242.68.1 to 10.242.69.25410.242.69.255510
3610.242.70.0/2310.242.70.1 to 10.242.71.25410.242.71.255510
3710.242.72.0/2310.242.72.1 to 10.242.73.25410.242.73.255510
3810.242.74.0/2310.242.74.1 to 10.242.75.25410.242.75.255510
3910.242.76.0/2310.242.76.1 to 10.242.77.25410.242.77.255510
4010.242.78.0/2310.242.78.1 to 10.242.79.25410.242.79.255510
4110.242.80.0/2310.242.80.1 to 10.242.81.25410.242.81.255510
4210.242.82.0/2310.242.82.1 to 10.242.83.25410.242.83.255510
4310.242.84.0/2310.242.84.1 to 10.242.85.25410.242.85.255510
4410.242.86.0/2310.242.86.1 to 10.242.87.25410.242.87.255510
4510.242.88.0/2310.242.88.1 to 10.242.89.25410.242.89.255510
4610.242.90.0/2310.242.90.1 to 10.242.91.25410.242.91.255510
4710.242.92.0/2310.242.92.1 to 10.242.93.25410.242.93.255510
4810.242.94.0/2310.242.94.1 to 10.242.95.25410.242.95.255510
4910.242.96.0/2310.242.96.1 to 10.242.97.25410.242.97.255510
5010.242.98.0/2310.242.98.1 to 10.242.99.25410.242.99.255510
5110.242.100.0/2310.242.100.1 to 10.242.101.25410.242.101.255510
5210.242.102.0/2310.242.102.1 to 10.242.103.25410.242.103.255510
5310.242.104.0/2310.242.104.1 to 10.242.105.25410.242.105.255510
5410.242.106.0/2310.242.106.1 to 10.242.107.25410.242.107.255510
5510.242.108.0/2310.242.108.1 to 10.242.109.25410.242.109.255510
5610.242.110.0/2310.242.110.1 to 10.242.111.25410.242.111.255510
5710.242.112.0/2310.242.112.1 to 10.242.113.25410.242.113.255510
5810.242.114.0/2310.242.114.1 to 10.242.115.25410.242.115.255510
5910.242.116.0/2310.242.116.1 to 10.242.117.25410.242.117.255510
6010.242.118.0/2310.242.118.1 to 10.242.119.25410.242.119.255510
6110.242.120.0/2310.242.120.1 to 10.242.121.25410.242.121.255510
6210.242.122.0/2310.242.122.1 to 10.242.123.25410.242.123.255510
6310.242.124.0/2310.242.124.1 to 10.242.125.25410.242.125.255510
6410.242.126.0/2310.242.126.1 to 10.242.127.25410.242.127.255510
6510.242.128.0/2310.242.128.1 to 10.242.129.25410.242.129.255510
6610.242.130.0/2310.242.130.1 to 10.242.131.25410.242.131.255510
6710.242.132.0/2310.242.132.1 to 10.242.133.25410.242.133.255510
6810.242.134.0/2310.242.134.1 to 10.242.135.25410.242.135.255510
6910.242.136.0/2310.242.136.1 to 10.242.137.25410.242.137.255510
7010.242.138.0/2310.242.138.1 to 10.242.139.25410.242.139.255510
7110.242.140.0/2310.242.140.1 to 10.242.141.25410.242.141.255510
7210.242.142.0/2310.242.142.1 to 10.242.143.25410.242.143.255510
7310.242.144.0/2310.242.144.1 to 10.242.145.25410.242.145.255510
7410.242.146.0/2310.242.146.1 to 10.242.147.25410.242.147.255510
7510.242.148.0/2310.242.148.1 to 10.242.149.25410.242.149.255510
7610.242.150.0/2310.242.150.1 to 10.242.151.25410.242.151.255510
7710.242.152.0/2310.242.152.1 to 10.242.153.25410.242.153.255510
7810.242.154.0/2310.242.154.1 to 10.242.155.25410.242.155.255510
7910.242.156.0/2310.242.156.1 to 10.242.157.25410.242.157.255510
8010.242.158.0/2310.242.158.1 to 10.242.159.25410.242.159.255510
8110.242.160.0/2310.242.160.1 to 10.242.161.25410.242.161.255510
8210.242.162.0/2310.242.162.1 to 10.242.163.25410.242.163.255510
8310.242.164.0/2310.242.164.1 to 10.242.165.25410.242.165.255510
8410.242.166.0/2310.242.166.1 to 10.242.167.25410.242.167.255510
8510.242.168.0/2310.242.168.1 to 10.242.169.25410.242.169.255510
8610.242.170.0/2310.242.170.1 to 10.242.171.25410.242.171.255510
8710.242.172.0/2310.242.172.1 to 10.242.173.25410.242.173.255510
8810.242.174.0/2310.242.174.1 to 10.242.175.25410.242.175.255510
8910.242.176.0/2310.242.176.1 to 10.242.177.25410.242.177.255510
9010.242.178.0/2310.242.178.1 to 10.242.179.25410.242.179.255510
9110.242.180.0/2310.242.180.1 to 10.242.181.25410.242.181.255510
9210.242.182.0/2310.242.182.1 to 10.242.183.25410.242.183.255510
9310.242.184.0/2310.242.184.1 to 10.242.185.25410.242.185.255510
9410.242.186.0/2310.242.186.1 to 10.242.187.25410.242.187.255510
9510.242.188.0/2310.242.188.1 to 10.242.189.25410.242.189.255510
9610.242.190.0/2310.242.190.1 to 10.242.191.25410.242.191.255510
9710.242.192.0/2310.242.192.1 to 10.242.193.25410.242.193.255510
9810.242.194.0/2310.242.194.1 to 10.242.195.25410.242.195.255510
9910.242.196.0/2310.242.196.1 to 10.242.197.25410.242.197.255510
10010.242.198.0/2310.242.198.1 to 10.242.199.25410.242.199.255510
10110.242.200.0/2310.242.200.1 to 10.242.201.25410.242.201.255510
10210.242.202.0/2310.242.202.1 to 10.242.203.25410.242.203.255510
10310.242.204.0/2310.242.204.1 to 10.242.205.25410.242.205.255510
10410.242.206.0/2310.242.206.1 to 10.242.207.25410.242.207.255510
10510.242.208.0/2310.242.208.1 to 10.242.209.25410.242.209.255510
10610.242.210.0/2310.242.210.1 to 10.242.211.25410.242.211.255510
10710.242.212.0/2310.242.212.1 to 10.242.213.25410.242.213.255510
10810.242.214.0/2310.242.214.1 to 10.242.215.25410.242.215.255510
10910.242.216.0/2310.242.216.1 to 10.242.217.25410.242.217.255510
11010.242.218.0/2310.242.218.1 to 10.242.219.25410.242.219.255510
11110.242.220.0/2310.242.220.1 to 10.242.221.25410.242.221.255510
11210.242.222.0/2310.242.222.1 to 10.242.223.25410.242.223.255510
11310.242.224.0/2310.242.224.1 to 10.242.225.25410.242.225.255510
11410.242.226.0/2310.242.226.1 to 10.242.227.25410.242.227.255510
11510.242.228.0/2310.242.228.1 to 10.242.229.25410.242.229.255510
11610.242.230.0/2310.242.230.1 to 10.242.231.25410.242.231.255510
11710.242.232.0/2310.242.232.1 to 10.242.233.25410.242.233.255510
11810.242.234.0/2310.242.234.1 to 10.242.235.25410.242.235.255510
11910.242.236.0/2310.242.236.1 to 10.242.237.25410.242.237.255510
12010.242.238.0/2310.242.238.1 to 10.242.239.25410.242.239.255510
12110.242.240.0/2310.242.240.1 to 10.242.241.25410.242.241.255510
12210.242.242.0/2310.242.242.1 to 10.242.243.25410.242.243.255510
12310.242.244.0/2310.242.244.1 to 10.242.245.25410.242.245.255510
12410.242.246.0/2310.242.246.1 to 10.242.247.25410.242.247.255510
12510.242.248.0/2310.242.248.1 to 10.242.249.25410.242.249.255510
12610.242.250.0/2310.242.250.1 to 10.242.251.25410.242.251.255510
12710.242.252.0/2310.242.252.1 to 10.242.253.25410.242.253.255510
12810.242.254.0/2310.242.254.1 to 10.242.255.25410.242.255.255510
12910.243.0.0/2310.243.0.1 to 10.243.1.25410.243.1.255510
13010.243.2.0/2310.243.2.1 to 10.243.3.25410.243.3.255510
13110.243.4.0/2310.243.4.1 to 10.243.5.25410.243.5.255510
13210.243.6.0/2310.243.6.1 to 10.243.7.25410.243.7.255510
13310.243.8.0/2310.243.8.1 to 10.243.9.25410.243.9.255510
13410.243.10.0/2310.243.10.1 to 10.243.11.25410.243.11.255510
13510.243.12.0/2310.243.12.1 to 10.243.13.25410.243.13.255510
13610.243.14.0/2310.243.14.1 to 10.243.15.25410.243.15.255510
13710.243.16.0/2310.243.16.1 to 10.243.17.25410.243.17.255510
13810.243.18.0/2310.243.18.1 to 10.243.19.25410.243.19.255510
13910.243.20.0/2310.243.20.1 to 10.243.21.25410.243.21.255510
14010.243.22.0/2310.243.22.1 to 10.243.23.25410.243.23.255510
14110.243.24.0/2310.243.24.1 to 10.243.25.25410.243.25.255510
14210.243.26.0/2310.243.26.1 to 10.243.27.25410.243.27.255510
14310.243.28.0/2310.243.28.1 to 10.243.29.25410.243.29.255510
14410.243.30.0/2310.243.30.1 to 10.243.31.25410.243.31.255510
14510.243.32.0/2310.243.32.1 to 10.243.33.25410.243.33.255510
14610.243.34.0/2310.243.34.1 to 10.243.35.25410.243.35.255510
14710.243.36.0/2310.243.36.1 to 10.243.37.25410.243.37.255510
14810.243.38.0/2310.243.38.1 to 10.243.39.25410.243.39.255510
14910.243.40.0/2310.243.40.1 to 10.243.41.25410.243.41.255510
15010.243.42.0/2310.243.42.1 to 10.243.43.25410.243.43.255510
15110.243.44.0/2310.243.44.1 to 10.243.45.25410.243.45.255510
15210.243.46.0/2310.243.46.1 to 10.243.47.25410.243.47.255510
15310.243.48.0/2310.243.48.1 to 10.243.49.25410.243.49.255510
15410.243.50.0/2310.243.50.1 to 10.243.51.25410.243.51.255510
15510.243.52.0/2310.243.52.1 to 10.243.53.25410.243.53.255510
15610.243.54.0/2310.243.54.1 to 10.243.55.25410.243.55.255510
15710.243.56.0/2310.243.56.1 to 10.243.57.25410.243.57.255510
15810.243.58.0/2310.243.58.1 to 10.243.59.25410.243.59.255510
15910.243.60.0/2310.243.60.1 to 10.243.61.25410.243.61.255510
16010.243.62.0/2310.243.62.1 to 10.243.63.25410.243.63.255510
16110.243.64.0/2310.243.64.1 to 10.243.65.25410.243.65.255510
16210.243.66.0/2310.243.66.1 to 10.243.67.25410.243.67.255510
16310.243.68.0/2310.243.68.1 to 10.243.69.25410.243.69.255510
16410.243.70.0/2310.243.70.1 to 10.243.71.25410.243.71.255510
16510.243.72.0/2310.243.72.1 to 10.243.73.25410.243.73.255510
16610.243.74.0/2310.243.74.1 to 10.243.75.25410.243.75.255510
16710.243.76.0/2310.243.76.1 to 10.243.77.25410.243.77.255510
16810.243.78.0/2310.243.78.1 to 10.243.79.25410.243.79.255510
16910.243.80.0/2310.243.80.1 to 10.243.81.25410.243.81.255510
17010.243.82.0/2310.243.82.1 to 10.243.83.25410.243.83.255510
17110.243.84.0/2310.243.84.1 to 10.243.85.25410.243.85.255510
17210.243.86.0/2310.243.86.1 to 10.243.87.25410.243.87.255510
17310.243.88.0/2310.243.88.1 to 10.243.89.25410.243.89.255510
17410.243.90.0/2310.243.90.1 to 10.243.91.25410.243.91.255510
17510.243.92.0/2310.243.92.1 to 10.243.93.25410.243.93.255510
17610.243.94.0/2310.243.94.1 to 10.243.95.25410.243.95.255510
17710.243.96.0/2310.243.96.1 to 10.243.97.25410.243.97.255510
17810.243.98.0/2310.243.98.1 to 10.243.99.25410.243.99.255510
17910.243.100.0/2310.243.100.1 to 10.243.101.25410.243.101.255510
18010.243.102.0/2310.243.102.1 to 10.243.103.25410.243.103.255510
18110.243.104.0/2310.243.104.1 to 10.243.105.25410.243.105.255510
18210.243.106.0/2310.243.106.1 to 10.243.107.25410.243.107.255510
18310.243.108.0/2310.243.108.1 to 10.243.109.25410.243.109.255510
18410.243.110.0/2310.243.110.1 to 10.243.111.25410.243.111.255510
18510.243.112.0/2310.243.112.1 to 10.243.113.25410.243.113.255510
18610.243.114.0/2310.243.114.1 to 10.243.115.25410.243.115.255510
18710.243.116.0/2310.243.116.1 to 10.243.117.25410.243.117.255510
18810.243.118.0/2310.243.118.1 to 10.243.119.25410.243.119.255510
18910.243.120.0/2310.243.120.1 to 10.243.121.25410.243.121.255510
19010.243.122.0/2310.243.122.1 to 10.243.123.25410.243.123.255510
19110.243.124.0/2310.243.124.1 to 10.243.125.25410.243.125.255510
19210.243.126.0/2310.243.126.1 to 10.243.127.25410.243.127.255510
19310.243.128.0/2310.243.128.1 to 10.243.129.25410.243.129.255510
19410.243.130.0/2310.243.130.1 to 10.243.131.25410.243.131.255510
19510.243.132.0/2310.243.132.1 to 10.243.133.25410.243.133.255510
19610.243.134.0/2310.243.134.1 to 10.243.135.25410.243.135.255510
19710.243.136.0/2310.243.136.1 to 10.243.137.25410.243.137.255510
19810.243.138.0/2310.243.138.1 to 10.243.139.25410.243.139.255510
19910.243.140.0/2310.243.140.1 to 10.243.141.25410.243.141.255510
20010.243.142.0/2310.243.142.1 to 10.243.143.25410.243.143.255510
20110.243.144.0/2310.243.144.1 to 10.243.145.25410.243.145.255510
20210.243.146.0/2310.243.146.1 to 10.243.147.25410.243.147.255510
20310.243.148.0/2310.243.148.1 to 10.243.149.25410.243.149.255510
20410.243.150.0/2310.243.150.1 to 10.243.151.25410.243.151.255510
20510.243.152.0/2310.243.152.1 to 10.243.153.25410.243.153.255510
20610.243.154.0/2310.243.154.1 to 10.243.155.25410.243.155.255510
20710.243.156.0/2310.243.156.1 to 10.243.157.25410.243.157.255510
20810.243.158.0/2310.243.158.1 to 10.243.159.25410.243.159.255510
20910.243.160.0/2310.243.160.1 to 10.243.161.25410.243.161.255510
21010.243.162.0/2310.243.162.1 to 10.243.163.25410.243.163.255510
21110.243.164.0/2310.243.164.1 to 10.243.165.25410.243.165.255510
21210.243.166.0/2310.243.166.1 to 10.243.167.25410.243.167.255510
21310.243.168.0/2310.243.168.1 to 10.243.169.25410.243.169.255510
21410.243.170.0/2310.243.170.1 to 10.243.171.25410.243.171.255510
21510.243.172.0/2310.243.172.1 to 10.243.173.25410.243.173.255510
21610.243.174.0/2310.243.174.1 to 10.243.175.25410.243.175.255510
21710.243.176.0/2310.243.176.1 to 10.243.177.25410.243.177.255510
21810.243.178.0/2310.243.178.1 to 10.243.179.25410.243.179.255510
21910.243.180.0/2310.243.180.1 to 10.243.181.25410.243.181.255510
22010.243.182.0/2310.243.182.1 to 10.243.183.25410.243.183.255510
22110.243.184.0/2310.243.184.1 to 10.243.185.25410.243.185.255510
22210.243.186.0/2310.243.186.1 to 10.243.187.25410.243.187.255510
22310.243.188.0/2310.243.188.1 to 10.243.189.25410.243.189.255510
22410.243.190.0/2310.243.190.1 to 10.243.191.25410.243.191.255510
22510.243.192.0/2310.243.192.1 to 10.243.193.25410.243.193.255510
22610.243.194.0/2310.243.194.1 to 10.243.195.25410.243.195.255510
22710.243.196.0/2310.243.196.1 to 10.243.197.25410.243.197.255510
22810.243.198.0/2310.243.198.1 to 10.243.199.25410.243.199.255510
22910.243.200.0/2310.243.200.1 to 10.243.201.25410.243.201.255510
23010.243.202.0/2310.243.202.1 to 10.243.203.25410.243.203.255510
23110.243.204.0/2310.243.204.1 to 10.243.205.25410.243.205.255510
23210.243.206.0/2310.243.206.1 to 10.243.207.25410.243.207.255510
23310.243.208.0/2310.243.208.1 to 10.243.209.25410.243.209.255510
23410.243.210.0/2310.243.210.1 to 10.243.211.25410.243.211.255510
23510.243.212.0/2310.243.212.1 to 10.243.213.25410.243.213.255510
23610.243.214.0/2310.243.214.1 to 10.243.215.25410.243.215.255510
23710.243.216.0/2310.243.216.1 to 10.243.217.25410.243.217.255510
23810.243.218.0/2310.243.218.1 to 10.243.219.25410.243.219.255510
23910.243.220.0/2310.243.220.1 to 10.243.221.25410.243.221.255510
24010.243.222.0/2310.243.222.1 to 10.243.223.25410.243.223.255510
24110.243.224.0/2310.243.224.1 to 10.243.225.25410.243.225.255510
24210.243.226.0/2310.243.226.1 to 10.243.227.25410.243.227.255510
24310.243.228.0/2310.243.228.1 to 10.243.229.25410.243.229.255510
24410.243.230.0/2310.243.230.1 to 10.243.231.25410.243.231.255510
24510.243.232.0/2310.243.232.1 to 10.243.233.25410.243.233.255510
24610.243.234.0/2310.243.234.1 to 10.243.235.25410.243.235.255510
24710.243.236.0/2310.243.236.1 to 10.243.237.25410.243.237.255510
24810.243.238.0/2310.243.238.1 to 10.243.239.25410.243.239.255510
24910.243.240.0/2310.243.240.1 to 10.243.241.25410.243.241.255510
25010.243.242.0/2310.243.242.1 to 10.243.243.25410.243.243.255510
25110.243.244.0/2310.243.244.1 to 10.243.245.25410.243.245.255510
25210.243.246.0/2310.243.246.1 to 10.243.247.25410.243.247.255510
25310.243.248.0/2310.243.248.1 to 10.243.249.25410.243.249.255510
25410.243.250.0/2310.243.250.1 to 10.243.251.25410.243.251.255510
25510.243.252.0/2310.243.252.1 to 10.243.253.25410.243.253.255510
25610.243.254.0/2310.243.254.1 to 10.243.255.25410.243.255.255510

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.