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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.

Network2.16.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
2.16.0.0
Broadcast address
2.23.255.255
First usable
2.16.0.1
Last usable
2.23.255.254
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 02100000 · Integer 34603008 to 35127295
Reverse DNS zones
16.2.in-addr.arpa
17.2.in-addr.arpa
18.2.in-addr.arpa
19.2.in-addr.arpa
20.2.in-addr.arpa
21.2.in-addr.arpa
22.2.in-addr.arpa
23.2.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
Address00000010.00010000.00000000.000000002.16.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network00000010.00010000.00000000.000000002.16.0.0
Broadcast00000010.00010111.11111111.111111112.23.255.255
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)

2.16.0.0/13 makes 1,024 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
12.16.0.0/232.16.0.1 to 2.16.1.2542.16.1.255510
22.16.2.0/232.16.2.1 to 2.16.3.2542.16.3.255510
32.16.4.0/232.16.4.1 to 2.16.5.2542.16.5.255510
42.16.6.0/232.16.6.1 to 2.16.7.2542.16.7.255510
52.16.8.0/232.16.8.1 to 2.16.9.2542.16.9.255510
62.16.10.0/232.16.10.1 to 2.16.11.2542.16.11.255510
72.16.12.0/232.16.12.1 to 2.16.13.2542.16.13.255510
82.16.14.0/232.16.14.1 to 2.16.15.2542.16.15.255510
92.16.16.0/232.16.16.1 to 2.16.17.2542.16.17.255510
102.16.18.0/232.16.18.1 to 2.16.19.2542.16.19.255510
112.16.20.0/232.16.20.1 to 2.16.21.2542.16.21.255510
122.16.22.0/232.16.22.1 to 2.16.23.2542.16.23.255510
132.16.24.0/232.16.24.1 to 2.16.25.2542.16.25.255510
142.16.26.0/232.16.26.1 to 2.16.27.2542.16.27.255510
152.16.28.0/232.16.28.1 to 2.16.29.2542.16.29.255510
162.16.30.0/232.16.30.1 to 2.16.31.2542.16.31.255510
172.16.32.0/232.16.32.1 to 2.16.33.2542.16.33.255510
182.16.34.0/232.16.34.1 to 2.16.35.2542.16.35.255510
192.16.36.0/232.16.36.1 to 2.16.37.2542.16.37.255510
202.16.38.0/232.16.38.1 to 2.16.39.2542.16.39.255510
212.16.40.0/232.16.40.1 to 2.16.41.2542.16.41.255510
222.16.42.0/232.16.42.1 to 2.16.43.2542.16.43.255510
232.16.44.0/232.16.44.1 to 2.16.45.2542.16.45.255510
242.16.46.0/232.16.46.1 to 2.16.47.2542.16.47.255510
252.16.48.0/232.16.48.1 to 2.16.49.2542.16.49.255510
262.16.50.0/232.16.50.1 to 2.16.51.2542.16.51.255510
272.16.52.0/232.16.52.1 to 2.16.53.2542.16.53.255510
282.16.54.0/232.16.54.1 to 2.16.55.2542.16.55.255510
292.16.56.0/232.16.56.1 to 2.16.57.2542.16.57.255510
302.16.58.0/232.16.58.1 to 2.16.59.2542.16.59.255510
312.16.60.0/232.16.60.1 to 2.16.61.2542.16.61.255510
322.16.62.0/232.16.62.1 to 2.16.63.2542.16.63.255510
332.16.64.0/232.16.64.1 to 2.16.65.2542.16.65.255510
342.16.66.0/232.16.66.1 to 2.16.67.2542.16.67.255510
352.16.68.0/232.16.68.1 to 2.16.69.2542.16.69.255510
362.16.70.0/232.16.70.1 to 2.16.71.2542.16.71.255510
372.16.72.0/232.16.72.1 to 2.16.73.2542.16.73.255510
382.16.74.0/232.16.74.1 to 2.16.75.2542.16.75.255510
392.16.76.0/232.16.76.1 to 2.16.77.2542.16.77.255510
402.16.78.0/232.16.78.1 to 2.16.79.2542.16.79.255510
412.16.80.0/232.16.80.1 to 2.16.81.2542.16.81.255510
422.16.82.0/232.16.82.1 to 2.16.83.2542.16.83.255510
432.16.84.0/232.16.84.1 to 2.16.85.2542.16.85.255510
442.16.86.0/232.16.86.1 to 2.16.87.2542.16.87.255510
452.16.88.0/232.16.88.1 to 2.16.89.2542.16.89.255510
462.16.90.0/232.16.90.1 to 2.16.91.2542.16.91.255510
472.16.92.0/232.16.92.1 to 2.16.93.2542.16.93.255510
482.16.94.0/232.16.94.1 to 2.16.95.2542.16.95.255510
492.16.96.0/232.16.96.1 to 2.16.97.2542.16.97.255510
502.16.98.0/232.16.98.1 to 2.16.99.2542.16.99.255510
512.16.100.0/232.16.100.1 to 2.16.101.2542.16.101.255510
522.16.102.0/232.16.102.1 to 2.16.103.2542.16.103.255510
532.16.104.0/232.16.104.1 to 2.16.105.2542.16.105.255510
542.16.106.0/232.16.106.1 to 2.16.107.2542.16.107.255510
552.16.108.0/232.16.108.1 to 2.16.109.2542.16.109.255510
562.16.110.0/232.16.110.1 to 2.16.111.2542.16.111.255510
572.16.112.0/232.16.112.1 to 2.16.113.2542.16.113.255510
582.16.114.0/232.16.114.1 to 2.16.115.2542.16.115.255510
592.16.116.0/232.16.116.1 to 2.16.117.2542.16.117.255510
602.16.118.0/232.16.118.1 to 2.16.119.2542.16.119.255510
612.16.120.0/232.16.120.1 to 2.16.121.2542.16.121.255510
622.16.122.0/232.16.122.1 to 2.16.123.2542.16.123.255510
632.16.124.0/232.16.124.1 to 2.16.125.2542.16.125.255510
642.16.126.0/232.16.126.1 to 2.16.127.2542.16.127.255510
652.16.128.0/232.16.128.1 to 2.16.129.2542.16.129.255510
662.16.130.0/232.16.130.1 to 2.16.131.2542.16.131.255510
672.16.132.0/232.16.132.1 to 2.16.133.2542.16.133.255510
682.16.134.0/232.16.134.1 to 2.16.135.2542.16.135.255510
692.16.136.0/232.16.136.1 to 2.16.137.2542.16.137.255510
702.16.138.0/232.16.138.1 to 2.16.139.2542.16.139.255510
712.16.140.0/232.16.140.1 to 2.16.141.2542.16.141.255510
722.16.142.0/232.16.142.1 to 2.16.143.2542.16.143.255510
732.16.144.0/232.16.144.1 to 2.16.145.2542.16.145.255510
742.16.146.0/232.16.146.1 to 2.16.147.2542.16.147.255510
752.16.148.0/232.16.148.1 to 2.16.149.2542.16.149.255510
762.16.150.0/232.16.150.1 to 2.16.151.2542.16.151.255510
772.16.152.0/232.16.152.1 to 2.16.153.2542.16.153.255510
782.16.154.0/232.16.154.1 to 2.16.155.2542.16.155.255510
792.16.156.0/232.16.156.1 to 2.16.157.2542.16.157.255510
802.16.158.0/232.16.158.1 to 2.16.159.2542.16.159.255510
812.16.160.0/232.16.160.1 to 2.16.161.2542.16.161.255510
822.16.162.0/232.16.162.1 to 2.16.163.2542.16.163.255510
832.16.164.0/232.16.164.1 to 2.16.165.2542.16.165.255510
842.16.166.0/232.16.166.1 to 2.16.167.2542.16.167.255510
852.16.168.0/232.16.168.1 to 2.16.169.2542.16.169.255510
862.16.170.0/232.16.170.1 to 2.16.171.2542.16.171.255510
872.16.172.0/232.16.172.1 to 2.16.173.2542.16.173.255510
882.16.174.0/232.16.174.1 to 2.16.175.2542.16.175.255510
892.16.176.0/232.16.176.1 to 2.16.177.2542.16.177.255510
902.16.178.0/232.16.178.1 to 2.16.179.2542.16.179.255510
912.16.180.0/232.16.180.1 to 2.16.181.2542.16.181.255510
922.16.182.0/232.16.182.1 to 2.16.183.2542.16.183.255510
932.16.184.0/232.16.184.1 to 2.16.185.2542.16.185.255510
942.16.186.0/232.16.186.1 to 2.16.187.2542.16.187.255510
952.16.188.0/232.16.188.1 to 2.16.189.2542.16.189.255510
962.16.190.0/232.16.190.1 to 2.16.191.2542.16.191.255510
972.16.192.0/232.16.192.1 to 2.16.193.2542.16.193.255510
982.16.194.0/232.16.194.1 to 2.16.195.2542.16.195.255510
992.16.196.0/232.16.196.1 to 2.16.197.2542.16.197.255510
1002.16.198.0/232.16.198.1 to 2.16.199.2542.16.199.255510
1012.16.200.0/232.16.200.1 to 2.16.201.2542.16.201.255510
1022.16.202.0/232.16.202.1 to 2.16.203.2542.16.203.255510
1032.16.204.0/232.16.204.1 to 2.16.205.2542.16.205.255510
1042.16.206.0/232.16.206.1 to 2.16.207.2542.16.207.255510
1052.16.208.0/232.16.208.1 to 2.16.209.2542.16.209.255510
1062.16.210.0/232.16.210.1 to 2.16.211.2542.16.211.255510
1072.16.212.0/232.16.212.1 to 2.16.213.2542.16.213.255510
1082.16.214.0/232.16.214.1 to 2.16.215.2542.16.215.255510
1092.16.216.0/232.16.216.1 to 2.16.217.2542.16.217.255510
1102.16.218.0/232.16.218.1 to 2.16.219.2542.16.219.255510
1112.16.220.0/232.16.220.1 to 2.16.221.2542.16.221.255510
1122.16.222.0/232.16.222.1 to 2.16.223.2542.16.223.255510
1132.16.224.0/232.16.224.1 to 2.16.225.2542.16.225.255510
1142.16.226.0/232.16.226.1 to 2.16.227.2542.16.227.255510
1152.16.228.0/232.16.228.1 to 2.16.229.2542.16.229.255510
1162.16.230.0/232.16.230.1 to 2.16.231.2542.16.231.255510
1172.16.232.0/232.16.232.1 to 2.16.233.2542.16.233.255510
1182.16.234.0/232.16.234.1 to 2.16.235.2542.16.235.255510
1192.16.236.0/232.16.236.1 to 2.16.237.2542.16.237.255510
1202.16.238.0/232.16.238.1 to 2.16.239.2542.16.239.255510
1212.16.240.0/232.16.240.1 to 2.16.241.2542.16.241.255510
1222.16.242.0/232.16.242.1 to 2.16.243.2542.16.243.255510
1232.16.244.0/232.16.244.1 to 2.16.245.2542.16.245.255510
1242.16.246.0/232.16.246.1 to 2.16.247.2542.16.247.255510
1252.16.248.0/232.16.248.1 to 2.16.249.2542.16.249.255510
1262.16.250.0/232.16.250.1 to 2.16.251.2542.16.251.255510
1272.16.252.0/232.16.252.1 to 2.16.253.2542.16.253.255510
1282.16.254.0/232.16.254.1 to 2.16.255.2542.16.255.255510
1292.17.0.0/232.17.0.1 to 2.17.1.2542.17.1.255510
1302.17.2.0/232.17.2.1 to 2.17.3.2542.17.3.255510
1312.17.4.0/232.17.4.1 to 2.17.5.2542.17.5.255510
1322.17.6.0/232.17.6.1 to 2.17.7.2542.17.7.255510
1332.17.8.0/232.17.8.1 to 2.17.9.2542.17.9.255510
1342.17.10.0/232.17.10.1 to 2.17.11.2542.17.11.255510
1352.17.12.0/232.17.12.1 to 2.17.13.2542.17.13.255510
1362.17.14.0/232.17.14.1 to 2.17.15.2542.17.15.255510
1372.17.16.0/232.17.16.1 to 2.17.17.2542.17.17.255510
1382.17.18.0/232.17.18.1 to 2.17.19.2542.17.19.255510
1392.17.20.0/232.17.20.1 to 2.17.21.2542.17.21.255510
1402.17.22.0/232.17.22.1 to 2.17.23.2542.17.23.255510
1412.17.24.0/232.17.24.1 to 2.17.25.2542.17.25.255510
1422.17.26.0/232.17.26.1 to 2.17.27.2542.17.27.255510
1432.17.28.0/232.17.28.1 to 2.17.29.2542.17.29.255510
1442.17.30.0/232.17.30.1 to 2.17.31.2542.17.31.255510
1452.17.32.0/232.17.32.1 to 2.17.33.2542.17.33.255510
1462.17.34.0/232.17.34.1 to 2.17.35.2542.17.35.255510
1472.17.36.0/232.17.36.1 to 2.17.37.2542.17.37.255510
1482.17.38.0/232.17.38.1 to 2.17.39.2542.17.39.255510
1492.17.40.0/232.17.40.1 to 2.17.41.2542.17.41.255510
1502.17.42.0/232.17.42.1 to 2.17.43.2542.17.43.255510
1512.17.44.0/232.17.44.1 to 2.17.45.2542.17.45.255510
1522.17.46.0/232.17.46.1 to 2.17.47.2542.17.47.255510
1532.17.48.0/232.17.48.1 to 2.17.49.2542.17.49.255510
1542.17.50.0/232.17.50.1 to 2.17.51.2542.17.51.255510
1552.17.52.0/232.17.52.1 to 2.17.53.2542.17.53.255510
1562.17.54.0/232.17.54.1 to 2.17.55.2542.17.55.255510
1572.17.56.0/232.17.56.1 to 2.17.57.2542.17.57.255510
1582.17.58.0/232.17.58.1 to 2.17.59.2542.17.59.255510
1592.17.60.0/232.17.60.1 to 2.17.61.2542.17.61.255510
1602.17.62.0/232.17.62.1 to 2.17.63.2542.17.63.255510
1612.17.64.0/232.17.64.1 to 2.17.65.2542.17.65.255510
1622.17.66.0/232.17.66.1 to 2.17.67.2542.17.67.255510
1632.17.68.0/232.17.68.1 to 2.17.69.2542.17.69.255510
1642.17.70.0/232.17.70.1 to 2.17.71.2542.17.71.255510
1652.17.72.0/232.17.72.1 to 2.17.73.2542.17.73.255510
1662.17.74.0/232.17.74.1 to 2.17.75.2542.17.75.255510
1672.17.76.0/232.17.76.1 to 2.17.77.2542.17.77.255510
1682.17.78.0/232.17.78.1 to 2.17.79.2542.17.79.255510
1692.17.80.0/232.17.80.1 to 2.17.81.2542.17.81.255510
1702.17.82.0/232.17.82.1 to 2.17.83.2542.17.83.255510
1712.17.84.0/232.17.84.1 to 2.17.85.2542.17.85.255510
1722.17.86.0/232.17.86.1 to 2.17.87.2542.17.87.255510
1732.17.88.0/232.17.88.1 to 2.17.89.2542.17.89.255510
1742.17.90.0/232.17.90.1 to 2.17.91.2542.17.91.255510
1752.17.92.0/232.17.92.1 to 2.17.93.2542.17.93.255510
1762.17.94.0/232.17.94.1 to 2.17.95.2542.17.95.255510
1772.17.96.0/232.17.96.1 to 2.17.97.2542.17.97.255510
1782.17.98.0/232.17.98.1 to 2.17.99.2542.17.99.255510
1792.17.100.0/232.17.100.1 to 2.17.101.2542.17.101.255510
1802.17.102.0/232.17.102.1 to 2.17.103.2542.17.103.255510
1812.17.104.0/232.17.104.1 to 2.17.105.2542.17.105.255510
1822.17.106.0/232.17.106.1 to 2.17.107.2542.17.107.255510
1832.17.108.0/232.17.108.1 to 2.17.109.2542.17.109.255510
1842.17.110.0/232.17.110.1 to 2.17.111.2542.17.111.255510
1852.17.112.0/232.17.112.1 to 2.17.113.2542.17.113.255510
1862.17.114.0/232.17.114.1 to 2.17.115.2542.17.115.255510
1872.17.116.0/232.17.116.1 to 2.17.117.2542.17.117.255510
1882.17.118.0/232.17.118.1 to 2.17.119.2542.17.119.255510
1892.17.120.0/232.17.120.1 to 2.17.121.2542.17.121.255510
1902.17.122.0/232.17.122.1 to 2.17.123.2542.17.123.255510
1912.17.124.0/232.17.124.1 to 2.17.125.2542.17.125.255510
1922.17.126.0/232.17.126.1 to 2.17.127.2542.17.127.255510
1932.17.128.0/232.17.128.1 to 2.17.129.2542.17.129.255510
1942.17.130.0/232.17.130.1 to 2.17.131.2542.17.131.255510
1952.17.132.0/232.17.132.1 to 2.17.133.2542.17.133.255510
1962.17.134.0/232.17.134.1 to 2.17.135.2542.17.135.255510
1972.17.136.0/232.17.136.1 to 2.17.137.2542.17.137.255510
1982.17.138.0/232.17.138.1 to 2.17.139.2542.17.139.255510
1992.17.140.0/232.17.140.1 to 2.17.141.2542.17.141.255510
2002.17.142.0/232.17.142.1 to 2.17.143.2542.17.143.255510
2012.17.144.0/232.17.144.1 to 2.17.145.2542.17.145.255510
2022.17.146.0/232.17.146.1 to 2.17.147.2542.17.147.255510
2032.17.148.0/232.17.148.1 to 2.17.149.2542.17.149.255510
2042.17.150.0/232.17.150.1 to 2.17.151.2542.17.151.255510
2052.17.152.0/232.17.152.1 to 2.17.153.2542.17.153.255510
2062.17.154.0/232.17.154.1 to 2.17.155.2542.17.155.255510
2072.17.156.0/232.17.156.1 to 2.17.157.2542.17.157.255510
2082.17.158.0/232.17.158.1 to 2.17.159.2542.17.159.255510
2092.17.160.0/232.17.160.1 to 2.17.161.2542.17.161.255510
2102.17.162.0/232.17.162.1 to 2.17.163.2542.17.163.255510
2112.17.164.0/232.17.164.1 to 2.17.165.2542.17.165.255510
2122.17.166.0/232.17.166.1 to 2.17.167.2542.17.167.255510
2132.17.168.0/232.17.168.1 to 2.17.169.2542.17.169.255510
2142.17.170.0/232.17.170.1 to 2.17.171.2542.17.171.255510
2152.17.172.0/232.17.172.1 to 2.17.173.2542.17.173.255510
2162.17.174.0/232.17.174.1 to 2.17.175.2542.17.175.255510
2172.17.176.0/232.17.176.1 to 2.17.177.2542.17.177.255510
2182.17.178.0/232.17.178.1 to 2.17.179.2542.17.179.255510
2192.17.180.0/232.17.180.1 to 2.17.181.2542.17.181.255510
2202.17.182.0/232.17.182.1 to 2.17.183.2542.17.183.255510
2212.17.184.0/232.17.184.1 to 2.17.185.2542.17.185.255510
2222.17.186.0/232.17.186.1 to 2.17.187.2542.17.187.255510
2232.17.188.0/232.17.188.1 to 2.17.189.2542.17.189.255510
2242.17.190.0/232.17.190.1 to 2.17.191.2542.17.191.255510
2252.17.192.0/232.17.192.1 to 2.17.193.2542.17.193.255510
2262.17.194.0/232.17.194.1 to 2.17.195.2542.17.195.255510
2272.17.196.0/232.17.196.1 to 2.17.197.2542.17.197.255510
2282.17.198.0/232.17.198.1 to 2.17.199.2542.17.199.255510
2292.17.200.0/232.17.200.1 to 2.17.201.2542.17.201.255510
2302.17.202.0/232.17.202.1 to 2.17.203.2542.17.203.255510
2312.17.204.0/232.17.204.1 to 2.17.205.2542.17.205.255510
2322.17.206.0/232.17.206.1 to 2.17.207.2542.17.207.255510
2332.17.208.0/232.17.208.1 to 2.17.209.2542.17.209.255510
2342.17.210.0/232.17.210.1 to 2.17.211.2542.17.211.255510
2352.17.212.0/232.17.212.1 to 2.17.213.2542.17.213.255510
2362.17.214.0/232.17.214.1 to 2.17.215.2542.17.215.255510
2372.17.216.0/232.17.216.1 to 2.17.217.2542.17.217.255510
2382.17.218.0/232.17.218.1 to 2.17.219.2542.17.219.255510
2392.17.220.0/232.17.220.1 to 2.17.221.2542.17.221.255510
2402.17.222.0/232.17.222.1 to 2.17.223.2542.17.223.255510
2412.17.224.0/232.17.224.1 to 2.17.225.2542.17.225.255510
2422.17.226.0/232.17.226.1 to 2.17.227.2542.17.227.255510
2432.17.228.0/232.17.228.1 to 2.17.229.2542.17.229.255510
2442.17.230.0/232.17.230.1 to 2.17.231.2542.17.231.255510
2452.17.232.0/232.17.232.1 to 2.17.233.2542.17.233.255510
2462.17.234.0/232.17.234.1 to 2.17.235.2542.17.235.255510
2472.17.236.0/232.17.236.1 to 2.17.237.2542.17.237.255510
2482.17.238.0/232.17.238.1 to 2.17.239.2542.17.239.255510
2492.17.240.0/232.17.240.1 to 2.17.241.2542.17.241.255510
2502.17.242.0/232.17.242.1 to 2.17.243.2542.17.243.255510
2512.17.244.0/232.17.244.1 to 2.17.245.2542.17.245.255510
2522.17.246.0/232.17.246.1 to 2.17.247.2542.17.247.255510
2532.17.248.0/232.17.248.1 to 2.17.249.2542.17.249.255510
2542.17.250.0/232.17.250.1 to 2.17.251.2542.17.251.255510
2552.17.252.0/232.17.252.1 to 2.17.253.2542.17.253.255510
2562.17.254.0/232.17.254.1 to 2.17.255.2542.17.255.255510

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.