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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.

Network2.8.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
2.8.0.0
Broadcast address
2.8.63.255
First usable
2.8.0.1
Last usable
2.8.63.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
A (default /8)
As numbers
Hex 02080000 · Integer 34078720 to 34095103
Reverse DNS zones
0.8.2.in-addr.arpa
1.8.2.in-addr.arpa
2.8.2.in-addr.arpa
3.8.2.in-addr.arpa
4.8.2.in-addr.arpa
5.8.2.in-addr.arpa
6.8.2.in-addr.arpa
7.8.2.in-addr.arpa
8.8.2.in-addr.arpa
9.8.2.in-addr.arpa
10.8.2.in-addr.arpa
11.8.2.in-addr.arpa
12.8.2.in-addr.arpa
13.8.2.in-addr.arpa
14.8.2.in-addr.arpa
15.8.2.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000010.00001000.00000000.000000002.8.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00000010.00001000.00000000.000000002.8.0.0
Broadcast00000010.00001000.00111111.111111112.8.63.255
Split into smaller subnets/26
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

2.8.0.0/18 makes 256 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
12.8.0.0/262.8.0.1 to 2.8.0.622.8.0.6362
22.8.0.64/262.8.0.65 to 2.8.0.1262.8.0.12762
32.8.0.128/262.8.0.129 to 2.8.0.1902.8.0.19162
42.8.0.192/262.8.0.193 to 2.8.0.2542.8.0.25562
52.8.1.0/262.8.1.1 to 2.8.1.622.8.1.6362
62.8.1.64/262.8.1.65 to 2.8.1.1262.8.1.12762
72.8.1.128/262.8.1.129 to 2.8.1.1902.8.1.19162
82.8.1.192/262.8.1.193 to 2.8.1.2542.8.1.25562
92.8.2.0/262.8.2.1 to 2.8.2.622.8.2.6362
102.8.2.64/262.8.2.65 to 2.8.2.1262.8.2.12762
112.8.2.128/262.8.2.129 to 2.8.2.1902.8.2.19162
122.8.2.192/262.8.2.193 to 2.8.2.2542.8.2.25562
132.8.3.0/262.8.3.1 to 2.8.3.622.8.3.6362
142.8.3.64/262.8.3.65 to 2.8.3.1262.8.3.12762
152.8.3.128/262.8.3.129 to 2.8.3.1902.8.3.19162
162.8.3.192/262.8.3.193 to 2.8.3.2542.8.3.25562
172.8.4.0/262.8.4.1 to 2.8.4.622.8.4.6362
182.8.4.64/262.8.4.65 to 2.8.4.1262.8.4.12762
192.8.4.128/262.8.4.129 to 2.8.4.1902.8.4.19162
202.8.4.192/262.8.4.193 to 2.8.4.2542.8.4.25562
212.8.5.0/262.8.5.1 to 2.8.5.622.8.5.6362
222.8.5.64/262.8.5.65 to 2.8.5.1262.8.5.12762
232.8.5.128/262.8.5.129 to 2.8.5.1902.8.5.19162
242.8.5.192/262.8.5.193 to 2.8.5.2542.8.5.25562
252.8.6.0/262.8.6.1 to 2.8.6.622.8.6.6362
262.8.6.64/262.8.6.65 to 2.8.6.1262.8.6.12762
272.8.6.128/262.8.6.129 to 2.8.6.1902.8.6.19162
282.8.6.192/262.8.6.193 to 2.8.6.2542.8.6.25562
292.8.7.0/262.8.7.1 to 2.8.7.622.8.7.6362
302.8.7.64/262.8.7.65 to 2.8.7.1262.8.7.12762
312.8.7.128/262.8.7.129 to 2.8.7.1902.8.7.19162
322.8.7.192/262.8.7.193 to 2.8.7.2542.8.7.25562
332.8.8.0/262.8.8.1 to 2.8.8.622.8.8.6362
342.8.8.64/262.8.8.65 to 2.8.8.1262.8.8.12762
352.8.8.128/262.8.8.129 to 2.8.8.1902.8.8.19162
362.8.8.192/262.8.8.193 to 2.8.8.2542.8.8.25562
372.8.9.0/262.8.9.1 to 2.8.9.622.8.9.6362
382.8.9.64/262.8.9.65 to 2.8.9.1262.8.9.12762
392.8.9.128/262.8.9.129 to 2.8.9.1902.8.9.19162
402.8.9.192/262.8.9.193 to 2.8.9.2542.8.9.25562
412.8.10.0/262.8.10.1 to 2.8.10.622.8.10.6362
422.8.10.64/262.8.10.65 to 2.8.10.1262.8.10.12762
432.8.10.128/262.8.10.129 to 2.8.10.1902.8.10.19162
442.8.10.192/262.8.10.193 to 2.8.10.2542.8.10.25562
452.8.11.0/262.8.11.1 to 2.8.11.622.8.11.6362
462.8.11.64/262.8.11.65 to 2.8.11.1262.8.11.12762
472.8.11.128/262.8.11.129 to 2.8.11.1902.8.11.19162
482.8.11.192/262.8.11.193 to 2.8.11.2542.8.11.25562
492.8.12.0/262.8.12.1 to 2.8.12.622.8.12.6362
502.8.12.64/262.8.12.65 to 2.8.12.1262.8.12.12762
512.8.12.128/262.8.12.129 to 2.8.12.1902.8.12.19162
522.8.12.192/262.8.12.193 to 2.8.12.2542.8.12.25562
532.8.13.0/262.8.13.1 to 2.8.13.622.8.13.6362
542.8.13.64/262.8.13.65 to 2.8.13.1262.8.13.12762
552.8.13.128/262.8.13.129 to 2.8.13.1902.8.13.19162
562.8.13.192/262.8.13.193 to 2.8.13.2542.8.13.25562
572.8.14.0/262.8.14.1 to 2.8.14.622.8.14.6362
582.8.14.64/262.8.14.65 to 2.8.14.1262.8.14.12762
592.8.14.128/262.8.14.129 to 2.8.14.1902.8.14.19162
602.8.14.192/262.8.14.193 to 2.8.14.2542.8.14.25562
612.8.15.0/262.8.15.1 to 2.8.15.622.8.15.6362
622.8.15.64/262.8.15.65 to 2.8.15.1262.8.15.12762
632.8.15.128/262.8.15.129 to 2.8.15.1902.8.15.19162
642.8.15.192/262.8.15.193 to 2.8.15.2542.8.15.25562
652.8.16.0/262.8.16.1 to 2.8.16.622.8.16.6362
662.8.16.64/262.8.16.65 to 2.8.16.1262.8.16.12762
672.8.16.128/262.8.16.129 to 2.8.16.1902.8.16.19162
682.8.16.192/262.8.16.193 to 2.8.16.2542.8.16.25562
692.8.17.0/262.8.17.1 to 2.8.17.622.8.17.6362
702.8.17.64/262.8.17.65 to 2.8.17.1262.8.17.12762
712.8.17.128/262.8.17.129 to 2.8.17.1902.8.17.19162
722.8.17.192/262.8.17.193 to 2.8.17.2542.8.17.25562
732.8.18.0/262.8.18.1 to 2.8.18.622.8.18.6362
742.8.18.64/262.8.18.65 to 2.8.18.1262.8.18.12762
752.8.18.128/262.8.18.129 to 2.8.18.1902.8.18.19162
762.8.18.192/262.8.18.193 to 2.8.18.2542.8.18.25562
772.8.19.0/262.8.19.1 to 2.8.19.622.8.19.6362
782.8.19.64/262.8.19.65 to 2.8.19.1262.8.19.12762
792.8.19.128/262.8.19.129 to 2.8.19.1902.8.19.19162
802.8.19.192/262.8.19.193 to 2.8.19.2542.8.19.25562
812.8.20.0/262.8.20.1 to 2.8.20.622.8.20.6362
822.8.20.64/262.8.20.65 to 2.8.20.1262.8.20.12762
832.8.20.128/262.8.20.129 to 2.8.20.1902.8.20.19162
842.8.20.192/262.8.20.193 to 2.8.20.2542.8.20.25562
852.8.21.0/262.8.21.1 to 2.8.21.622.8.21.6362
862.8.21.64/262.8.21.65 to 2.8.21.1262.8.21.12762
872.8.21.128/262.8.21.129 to 2.8.21.1902.8.21.19162
882.8.21.192/262.8.21.193 to 2.8.21.2542.8.21.25562
892.8.22.0/262.8.22.1 to 2.8.22.622.8.22.6362
902.8.22.64/262.8.22.65 to 2.8.22.1262.8.22.12762
912.8.22.128/262.8.22.129 to 2.8.22.1902.8.22.19162
922.8.22.192/262.8.22.193 to 2.8.22.2542.8.22.25562
932.8.23.0/262.8.23.1 to 2.8.23.622.8.23.6362
942.8.23.64/262.8.23.65 to 2.8.23.1262.8.23.12762
952.8.23.128/262.8.23.129 to 2.8.23.1902.8.23.19162
962.8.23.192/262.8.23.193 to 2.8.23.2542.8.23.25562
972.8.24.0/262.8.24.1 to 2.8.24.622.8.24.6362
982.8.24.64/262.8.24.65 to 2.8.24.1262.8.24.12762
992.8.24.128/262.8.24.129 to 2.8.24.1902.8.24.19162
1002.8.24.192/262.8.24.193 to 2.8.24.2542.8.24.25562
1012.8.25.0/262.8.25.1 to 2.8.25.622.8.25.6362
1022.8.25.64/262.8.25.65 to 2.8.25.1262.8.25.12762
1032.8.25.128/262.8.25.129 to 2.8.25.1902.8.25.19162
1042.8.25.192/262.8.25.193 to 2.8.25.2542.8.25.25562
1052.8.26.0/262.8.26.1 to 2.8.26.622.8.26.6362
1062.8.26.64/262.8.26.65 to 2.8.26.1262.8.26.12762
1072.8.26.128/262.8.26.129 to 2.8.26.1902.8.26.19162
1082.8.26.192/262.8.26.193 to 2.8.26.2542.8.26.25562
1092.8.27.0/262.8.27.1 to 2.8.27.622.8.27.6362
1102.8.27.64/262.8.27.65 to 2.8.27.1262.8.27.12762
1112.8.27.128/262.8.27.129 to 2.8.27.1902.8.27.19162
1122.8.27.192/262.8.27.193 to 2.8.27.2542.8.27.25562
1132.8.28.0/262.8.28.1 to 2.8.28.622.8.28.6362
1142.8.28.64/262.8.28.65 to 2.8.28.1262.8.28.12762
1152.8.28.128/262.8.28.129 to 2.8.28.1902.8.28.19162
1162.8.28.192/262.8.28.193 to 2.8.28.2542.8.28.25562
1172.8.29.0/262.8.29.1 to 2.8.29.622.8.29.6362
1182.8.29.64/262.8.29.65 to 2.8.29.1262.8.29.12762
1192.8.29.128/262.8.29.129 to 2.8.29.1902.8.29.19162
1202.8.29.192/262.8.29.193 to 2.8.29.2542.8.29.25562
1212.8.30.0/262.8.30.1 to 2.8.30.622.8.30.6362
1222.8.30.64/262.8.30.65 to 2.8.30.1262.8.30.12762
1232.8.30.128/262.8.30.129 to 2.8.30.1902.8.30.19162
1242.8.30.192/262.8.30.193 to 2.8.30.2542.8.30.25562
1252.8.31.0/262.8.31.1 to 2.8.31.622.8.31.6362
1262.8.31.64/262.8.31.65 to 2.8.31.1262.8.31.12762
1272.8.31.128/262.8.31.129 to 2.8.31.1902.8.31.19162
1282.8.31.192/262.8.31.193 to 2.8.31.2542.8.31.25562
1292.8.32.0/262.8.32.1 to 2.8.32.622.8.32.6362
1302.8.32.64/262.8.32.65 to 2.8.32.1262.8.32.12762
1312.8.32.128/262.8.32.129 to 2.8.32.1902.8.32.19162
1322.8.32.192/262.8.32.193 to 2.8.32.2542.8.32.25562
1332.8.33.0/262.8.33.1 to 2.8.33.622.8.33.6362
1342.8.33.64/262.8.33.65 to 2.8.33.1262.8.33.12762
1352.8.33.128/262.8.33.129 to 2.8.33.1902.8.33.19162
1362.8.33.192/262.8.33.193 to 2.8.33.2542.8.33.25562
1372.8.34.0/262.8.34.1 to 2.8.34.622.8.34.6362
1382.8.34.64/262.8.34.65 to 2.8.34.1262.8.34.12762
1392.8.34.128/262.8.34.129 to 2.8.34.1902.8.34.19162
1402.8.34.192/262.8.34.193 to 2.8.34.2542.8.34.25562
1412.8.35.0/262.8.35.1 to 2.8.35.622.8.35.6362
1422.8.35.64/262.8.35.65 to 2.8.35.1262.8.35.12762
1432.8.35.128/262.8.35.129 to 2.8.35.1902.8.35.19162
1442.8.35.192/262.8.35.193 to 2.8.35.2542.8.35.25562
1452.8.36.0/262.8.36.1 to 2.8.36.622.8.36.6362
1462.8.36.64/262.8.36.65 to 2.8.36.1262.8.36.12762
1472.8.36.128/262.8.36.129 to 2.8.36.1902.8.36.19162
1482.8.36.192/262.8.36.193 to 2.8.36.2542.8.36.25562
1492.8.37.0/262.8.37.1 to 2.8.37.622.8.37.6362
1502.8.37.64/262.8.37.65 to 2.8.37.1262.8.37.12762
1512.8.37.128/262.8.37.129 to 2.8.37.1902.8.37.19162
1522.8.37.192/262.8.37.193 to 2.8.37.2542.8.37.25562
1532.8.38.0/262.8.38.1 to 2.8.38.622.8.38.6362
1542.8.38.64/262.8.38.65 to 2.8.38.1262.8.38.12762
1552.8.38.128/262.8.38.129 to 2.8.38.1902.8.38.19162
1562.8.38.192/262.8.38.193 to 2.8.38.2542.8.38.25562
1572.8.39.0/262.8.39.1 to 2.8.39.622.8.39.6362
1582.8.39.64/262.8.39.65 to 2.8.39.1262.8.39.12762
1592.8.39.128/262.8.39.129 to 2.8.39.1902.8.39.19162
1602.8.39.192/262.8.39.193 to 2.8.39.2542.8.39.25562
1612.8.40.0/262.8.40.1 to 2.8.40.622.8.40.6362
1622.8.40.64/262.8.40.65 to 2.8.40.1262.8.40.12762
1632.8.40.128/262.8.40.129 to 2.8.40.1902.8.40.19162
1642.8.40.192/262.8.40.193 to 2.8.40.2542.8.40.25562
1652.8.41.0/262.8.41.1 to 2.8.41.622.8.41.6362
1662.8.41.64/262.8.41.65 to 2.8.41.1262.8.41.12762
1672.8.41.128/262.8.41.129 to 2.8.41.1902.8.41.19162
1682.8.41.192/262.8.41.193 to 2.8.41.2542.8.41.25562
1692.8.42.0/262.8.42.1 to 2.8.42.622.8.42.6362
1702.8.42.64/262.8.42.65 to 2.8.42.1262.8.42.12762
1712.8.42.128/262.8.42.129 to 2.8.42.1902.8.42.19162
1722.8.42.192/262.8.42.193 to 2.8.42.2542.8.42.25562
1732.8.43.0/262.8.43.1 to 2.8.43.622.8.43.6362
1742.8.43.64/262.8.43.65 to 2.8.43.1262.8.43.12762
1752.8.43.128/262.8.43.129 to 2.8.43.1902.8.43.19162
1762.8.43.192/262.8.43.193 to 2.8.43.2542.8.43.25562
1772.8.44.0/262.8.44.1 to 2.8.44.622.8.44.6362
1782.8.44.64/262.8.44.65 to 2.8.44.1262.8.44.12762
1792.8.44.128/262.8.44.129 to 2.8.44.1902.8.44.19162
1802.8.44.192/262.8.44.193 to 2.8.44.2542.8.44.25562
1812.8.45.0/262.8.45.1 to 2.8.45.622.8.45.6362
1822.8.45.64/262.8.45.65 to 2.8.45.1262.8.45.12762
1832.8.45.128/262.8.45.129 to 2.8.45.1902.8.45.19162
1842.8.45.192/262.8.45.193 to 2.8.45.2542.8.45.25562
1852.8.46.0/262.8.46.1 to 2.8.46.622.8.46.6362
1862.8.46.64/262.8.46.65 to 2.8.46.1262.8.46.12762
1872.8.46.128/262.8.46.129 to 2.8.46.1902.8.46.19162
1882.8.46.192/262.8.46.193 to 2.8.46.2542.8.46.25562
1892.8.47.0/262.8.47.1 to 2.8.47.622.8.47.6362
1902.8.47.64/262.8.47.65 to 2.8.47.1262.8.47.12762
1912.8.47.128/262.8.47.129 to 2.8.47.1902.8.47.19162
1922.8.47.192/262.8.47.193 to 2.8.47.2542.8.47.25562
1932.8.48.0/262.8.48.1 to 2.8.48.622.8.48.6362
1942.8.48.64/262.8.48.65 to 2.8.48.1262.8.48.12762
1952.8.48.128/262.8.48.129 to 2.8.48.1902.8.48.19162
1962.8.48.192/262.8.48.193 to 2.8.48.2542.8.48.25562
1972.8.49.0/262.8.49.1 to 2.8.49.622.8.49.6362
1982.8.49.64/262.8.49.65 to 2.8.49.1262.8.49.12762
1992.8.49.128/262.8.49.129 to 2.8.49.1902.8.49.19162
2002.8.49.192/262.8.49.193 to 2.8.49.2542.8.49.25562
2012.8.50.0/262.8.50.1 to 2.8.50.622.8.50.6362
2022.8.50.64/262.8.50.65 to 2.8.50.1262.8.50.12762
2032.8.50.128/262.8.50.129 to 2.8.50.1902.8.50.19162
2042.8.50.192/262.8.50.193 to 2.8.50.2542.8.50.25562
2052.8.51.0/262.8.51.1 to 2.8.51.622.8.51.6362
2062.8.51.64/262.8.51.65 to 2.8.51.1262.8.51.12762
2072.8.51.128/262.8.51.129 to 2.8.51.1902.8.51.19162
2082.8.51.192/262.8.51.193 to 2.8.51.2542.8.51.25562
2092.8.52.0/262.8.52.1 to 2.8.52.622.8.52.6362
2102.8.52.64/262.8.52.65 to 2.8.52.1262.8.52.12762
2112.8.52.128/262.8.52.129 to 2.8.52.1902.8.52.19162
2122.8.52.192/262.8.52.193 to 2.8.52.2542.8.52.25562
2132.8.53.0/262.8.53.1 to 2.8.53.622.8.53.6362
2142.8.53.64/262.8.53.65 to 2.8.53.1262.8.53.12762
2152.8.53.128/262.8.53.129 to 2.8.53.1902.8.53.19162
2162.8.53.192/262.8.53.193 to 2.8.53.2542.8.53.25562
2172.8.54.0/262.8.54.1 to 2.8.54.622.8.54.6362
2182.8.54.64/262.8.54.65 to 2.8.54.1262.8.54.12762
2192.8.54.128/262.8.54.129 to 2.8.54.1902.8.54.19162
2202.8.54.192/262.8.54.193 to 2.8.54.2542.8.54.25562
2212.8.55.0/262.8.55.1 to 2.8.55.622.8.55.6362
2222.8.55.64/262.8.55.65 to 2.8.55.1262.8.55.12762
2232.8.55.128/262.8.55.129 to 2.8.55.1902.8.55.19162
2242.8.55.192/262.8.55.193 to 2.8.55.2542.8.55.25562
2252.8.56.0/262.8.56.1 to 2.8.56.622.8.56.6362
2262.8.56.64/262.8.56.65 to 2.8.56.1262.8.56.12762
2272.8.56.128/262.8.56.129 to 2.8.56.1902.8.56.19162
2282.8.56.192/262.8.56.193 to 2.8.56.2542.8.56.25562
2292.8.57.0/262.8.57.1 to 2.8.57.622.8.57.6362
2302.8.57.64/262.8.57.65 to 2.8.57.1262.8.57.12762
2312.8.57.128/262.8.57.129 to 2.8.57.1902.8.57.19162
2322.8.57.192/262.8.57.193 to 2.8.57.2542.8.57.25562
2332.8.58.0/262.8.58.1 to 2.8.58.622.8.58.6362
2342.8.58.64/262.8.58.65 to 2.8.58.1262.8.58.12762
2352.8.58.128/262.8.58.129 to 2.8.58.1902.8.58.19162
2362.8.58.192/262.8.58.193 to 2.8.58.2542.8.58.25562
2372.8.59.0/262.8.59.1 to 2.8.59.622.8.59.6362
2382.8.59.64/262.8.59.65 to 2.8.59.1262.8.59.12762
2392.8.59.128/262.8.59.129 to 2.8.59.1902.8.59.19162
2402.8.59.192/262.8.59.193 to 2.8.59.2542.8.59.25562
2412.8.60.0/262.8.60.1 to 2.8.60.622.8.60.6362
2422.8.60.64/262.8.60.65 to 2.8.60.1262.8.60.12762
2432.8.60.128/262.8.60.129 to 2.8.60.1902.8.60.19162
2442.8.60.192/262.8.60.193 to 2.8.60.2542.8.60.25562
2452.8.61.0/262.8.61.1 to 2.8.61.622.8.61.6362
2462.8.61.64/262.8.61.65 to 2.8.61.1262.8.61.12762
2472.8.61.128/262.8.61.129 to 2.8.61.1902.8.61.19162
2482.8.61.192/262.8.61.193 to 2.8.61.2542.8.61.25562
2492.8.62.0/262.8.62.1 to 2.8.62.622.8.62.6362
2502.8.62.64/262.8.62.65 to 2.8.62.1262.8.62.12762
2512.8.62.128/262.8.62.129 to 2.8.62.1902.8.62.19162
2522.8.62.192/262.8.62.193 to 2.8.62.2542.8.62.25562
2532.8.63.0/262.8.63.1 to 2.8.63.622.8.63.6362
2542.8.63.64/262.8.63.65 to 2.8.63.1262.8.63.12762
2552.8.63.128/262.8.63.129 to 2.8.63.1902.8.63.19162
2562.8.63.192/262.8.63.193 to 2.8.63.2542.8.63.25562

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.