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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.

Network3.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
3.128.0.0
Broadcast address
3.191.255.255
First usable
3.128.0.1
Last usable
3.191.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 03800000 · Integer 58720256 to 62914559
Reverse DNS zones
128.3.in-addr.arpa
129.3.in-addr.arpa
130.3.in-addr.arpa
131.3.in-addr.arpa
132.3.in-addr.arpa
133.3.in-addr.arpa
134.3.in-addr.arpa
135.3.in-addr.arpa
136.3.in-addr.arpa
137.3.in-addr.arpa
138.3.in-addr.arpa
139.3.in-addr.arpa
140.3.in-addr.arpa
141.3.in-addr.arpa
142.3.in-addr.arpa
143.3.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000011.10000000.00000000.000000003.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00000011.10000000.00000000.000000003.128.0.0
Broadcast00000011.10111111.11111111.111111113.191.255.255
Split into smaller subnets/20
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

3.128.0.0/10 makes 1,024 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
13.128.0.0/203.128.0.1 to 3.128.15.2543.128.15.2554,094
23.128.16.0/203.128.16.1 to 3.128.31.2543.128.31.2554,094
33.128.32.0/203.128.32.1 to 3.128.47.2543.128.47.2554,094
43.128.48.0/203.128.48.1 to 3.128.63.2543.128.63.2554,094
53.128.64.0/203.128.64.1 to 3.128.79.2543.128.79.2554,094
63.128.80.0/203.128.80.1 to 3.128.95.2543.128.95.2554,094
73.128.96.0/203.128.96.1 to 3.128.111.2543.128.111.2554,094
83.128.112.0/203.128.112.1 to 3.128.127.2543.128.127.2554,094
93.128.128.0/203.128.128.1 to 3.128.143.2543.128.143.2554,094
103.128.144.0/203.128.144.1 to 3.128.159.2543.128.159.2554,094
113.128.160.0/203.128.160.1 to 3.128.175.2543.128.175.2554,094
123.128.176.0/203.128.176.1 to 3.128.191.2543.128.191.2554,094
133.128.192.0/203.128.192.1 to 3.128.207.2543.128.207.2554,094
143.128.208.0/203.128.208.1 to 3.128.223.2543.128.223.2554,094
153.128.224.0/203.128.224.1 to 3.128.239.2543.128.239.2554,094
163.128.240.0/203.128.240.1 to 3.128.255.2543.128.255.2554,094
173.129.0.0/203.129.0.1 to 3.129.15.2543.129.15.2554,094
183.129.16.0/203.129.16.1 to 3.129.31.2543.129.31.2554,094
193.129.32.0/203.129.32.1 to 3.129.47.2543.129.47.2554,094
203.129.48.0/203.129.48.1 to 3.129.63.2543.129.63.2554,094
213.129.64.0/203.129.64.1 to 3.129.79.2543.129.79.2554,094
223.129.80.0/203.129.80.1 to 3.129.95.2543.129.95.2554,094
233.129.96.0/203.129.96.1 to 3.129.111.2543.129.111.2554,094
243.129.112.0/203.129.112.1 to 3.129.127.2543.129.127.2554,094
253.129.128.0/203.129.128.1 to 3.129.143.2543.129.143.2554,094
263.129.144.0/203.129.144.1 to 3.129.159.2543.129.159.2554,094
273.129.160.0/203.129.160.1 to 3.129.175.2543.129.175.2554,094
283.129.176.0/203.129.176.1 to 3.129.191.2543.129.191.2554,094
293.129.192.0/203.129.192.1 to 3.129.207.2543.129.207.2554,094
303.129.208.0/203.129.208.1 to 3.129.223.2543.129.223.2554,094
313.129.224.0/203.129.224.1 to 3.129.239.2543.129.239.2554,094
323.129.240.0/203.129.240.1 to 3.129.255.2543.129.255.2554,094
333.130.0.0/203.130.0.1 to 3.130.15.2543.130.15.2554,094
343.130.16.0/203.130.16.1 to 3.130.31.2543.130.31.2554,094
353.130.32.0/203.130.32.1 to 3.130.47.2543.130.47.2554,094
363.130.48.0/203.130.48.1 to 3.130.63.2543.130.63.2554,094
373.130.64.0/203.130.64.1 to 3.130.79.2543.130.79.2554,094
383.130.80.0/203.130.80.1 to 3.130.95.2543.130.95.2554,094
393.130.96.0/203.130.96.1 to 3.130.111.2543.130.111.2554,094
403.130.112.0/203.130.112.1 to 3.130.127.2543.130.127.2554,094
413.130.128.0/203.130.128.1 to 3.130.143.2543.130.143.2554,094
423.130.144.0/203.130.144.1 to 3.130.159.2543.130.159.2554,094
433.130.160.0/203.130.160.1 to 3.130.175.2543.130.175.2554,094
443.130.176.0/203.130.176.1 to 3.130.191.2543.130.191.2554,094
453.130.192.0/203.130.192.1 to 3.130.207.2543.130.207.2554,094
463.130.208.0/203.130.208.1 to 3.130.223.2543.130.223.2554,094
473.130.224.0/203.130.224.1 to 3.130.239.2543.130.239.2554,094
483.130.240.0/203.130.240.1 to 3.130.255.2543.130.255.2554,094
493.131.0.0/203.131.0.1 to 3.131.15.2543.131.15.2554,094
503.131.16.0/203.131.16.1 to 3.131.31.2543.131.31.2554,094
513.131.32.0/203.131.32.1 to 3.131.47.2543.131.47.2554,094
523.131.48.0/203.131.48.1 to 3.131.63.2543.131.63.2554,094
533.131.64.0/203.131.64.1 to 3.131.79.2543.131.79.2554,094
543.131.80.0/203.131.80.1 to 3.131.95.2543.131.95.2554,094
553.131.96.0/203.131.96.1 to 3.131.111.2543.131.111.2554,094
563.131.112.0/203.131.112.1 to 3.131.127.2543.131.127.2554,094
573.131.128.0/203.131.128.1 to 3.131.143.2543.131.143.2554,094
583.131.144.0/203.131.144.1 to 3.131.159.2543.131.159.2554,094
593.131.160.0/203.131.160.1 to 3.131.175.2543.131.175.2554,094
603.131.176.0/203.131.176.1 to 3.131.191.2543.131.191.2554,094
613.131.192.0/203.131.192.1 to 3.131.207.2543.131.207.2554,094
623.131.208.0/203.131.208.1 to 3.131.223.2543.131.223.2554,094
633.131.224.0/203.131.224.1 to 3.131.239.2543.131.239.2554,094
643.131.240.0/203.131.240.1 to 3.131.255.2543.131.255.2554,094
653.132.0.0/203.132.0.1 to 3.132.15.2543.132.15.2554,094
663.132.16.0/203.132.16.1 to 3.132.31.2543.132.31.2554,094
673.132.32.0/203.132.32.1 to 3.132.47.2543.132.47.2554,094
683.132.48.0/203.132.48.1 to 3.132.63.2543.132.63.2554,094
693.132.64.0/203.132.64.1 to 3.132.79.2543.132.79.2554,094
703.132.80.0/203.132.80.1 to 3.132.95.2543.132.95.2554,094
713.132.96.0/203.132.96.1 to 3.132.111.2543.132.111.2554,094
723.132.112.0/203.132.112.1 to 3.132.127.2543.132.127.2554,094
733.132.128.0/203.132.128.1 to 3.132.143.2543.132.143.2554,094
743.132.144.0/203.132.144.1 to 3.132.159.2543.132.159.2554,094
753.132.160.0/203.132.160.1 to 3.132.175.2543.132.175.2554,094
763.132.176.0/203.132.176.1 to 3.132.191.2543.132.191.2554,094
773.132.192.0/203.132.192.1 to 3.132.207.2543.132.207.2554,094
783.132.208.0/203.132.208.1 to 3.132.223.2543.132.223.2554,094
793.132.224.0/203.132.224.1 to 3.132.239.2543.132.239.2554,094
803.132.240.0/203.132.240.1 to 3.132.255.2543.132.255.2554,094
813.133.0.0/203.133.0.1 to 3.133.15.2543.133.15.2554,094
823.133.16.0/203.133.16.1 to 3.133.31.2543.133.31.2554,094
833.133.32.0/203.133.32.1 to 3.133.47.2543.133.47.2554,094
843.133.48.0/203.133.48.1 to 3.133.63.2543.133.63.2554,094
853.133.64.0/203.133.64.1 to 3.133.79.2543.133.79.2554,094
863.133.80.0/203.133.80.1 to 3.133.95.2543.133.95.2554,094
873.133.96.0/203.133.96.1 to 3.133.111.2543.133.111.2554,094
883.133.112.0/203.133.112.1 to 3.133.127.2543.133.127.2554,094
893.133.128.0/203.133.128.1 to 3.133.143.2543.133.143.2554,094
903.133.144.0/203.133.144.1 to 3.133.159.2543.133.159.2554,094
913.133.160.0/203.133.160.1 to 3.133.175.2543.133.175.2554,094
923.133.176.0/203.133.176.1 to 3.133.191.2543.133.191.2554,094
933.133.192.0/203.133.192.1 to 3.133.207.2543.133.207.2554,094
943.133.208.0/203.133.208.1 to 3.133.223.2543.133.223.2554,094
953.133.224.0/203.133.224.1 to 3.133.239.2543.133.239.2554,094
963.133.240.0/203.133.240.1 to 3.133.255.2543.133.255.2554,094
973.134.0.0/203.134.0.1 to 3.134.15.2543.134.15.2554,094
983.134.16.0/203.134.16.1 to 3.134.31.2543.134.31.2554,094
993.134.32.0/203.134.32.1 to 3.134.47.2543.134.47.2554,094
1003.134.48.0/203.134.48.1 to 3.134.63.2543.134.63.2554,094
1013.134.64.0/203.134.64.1 to 3.134.79.2543.134.79.2554,094
1023.134.80.0/203.134.80.1 to 3.134.95.2543.134.95.2554,094
1033.134.96.0/203.134.96.1 to 3.134.111.2543.134.111.2554,094
1043.134.112.0/203.134.112.1 to 3.134.127.2543.134.127.2554,094
1053.134.128.0/203.134.128.1 to 3.134.143.2543.134.143.2554,094
1063.134.144.0/203.134.144.1 to 3.134.159.2543.134.159.2554,094
1073.134.160.0/203.134.160.1 to 3.134.175.2543.134.175.2554,094
1083.134.176.0/203.134.176.1 to 3.134.191.2543.134.191.2554,094
1093.134.192.0/203.134.192.1 to 3.134.207.2543.134.207.2554,094
1103.134.208.0/203.134.208.1 to 3.134.223.2543.134.223.2554,094
1113.134.224.0/203.134.224.1 to 3.134.239.2543.134.239.2554,094
1123.134.240.0/203.134.240.1 to 3.134.255.2543.134.255.2554,094
1133.135.0.0/203.135.0.1 to 3.135.15.2543.135.15.2554,094
1143.135.16.0/203.135.16.1 to 3.135.31.2543.135.31.2554,094
1153.135.32.0/203.135.32.1 to 3.135.47.2543.135.47.2554,094
1163.135.48.0/203.135.48.1 to 3.135.63.2543.135.63.2554,094
1173.135.64.0/203.135.64.1 to 3.135.79.2543.135.79.2554,094
1183.135.80.0/203.135.80.1 to 3.135.95.2543.135.95.2554,094
1193.135.96.0/203.135.96.1 to 3.135.111.2543.135.111.2554,094
1203.135.112.0/203.135.112.1 to 3.135.127.2543.135.127.2554,094
1213.135.128.0/203.135.128.1 to 3.135.143.2543.135.143.2554,094
1223.135.144.0/203.135.144.1 to 3.135.159.2543.135.159.2554,094
1233.135.160.0/203.135.160.1 to 3.135.175.2543.135.175.2554,094
1243.135.176.0/203.135.176.1 to 3.135.191.2543.135.191.2554,094
1253.135.192.0/203.135.192.1 to 3.135.207.2543.135.207.2554,094
1263.135.208.0/203.135.208.1 to 3.135.223.2543.135.223.2554,094
1273.135.224.0/203.135.224.1 to 3.135.239.2543.135.239.2554,094
1283.135.240.0/203.135.240.1 to 3.135.255.2543.135.255.2554,094
1293.136.0.0/203.136.0.1 to 3.136.15.2543.136.15.2554,094
1303.136.16.0/203.136.16.1 to 3.136.31.2543.136.31.2554,094
1313.136.32.0/203.136.32.1 to 3.136.47.2543.136.47.2554,094
1323.136.48.0/203.136.48.1 to 3.136.63.2543.136.63.2554,094
1333.136.64.0/203.136.64.1 to 3.136.79.2543.136.79.2554,094
1343.136.80.0/203.136.80.1 to 3.136.95.2543.136.95.2554,094
1353.136.96.0/203.136.96.1 to 3.136.111.2543.136.111.2554,094
1363.136.112.0/203.136.112.1 to 3.136.127.2543.136.127.2554,094
1373.136.128.0/203.136.128.1 to 3.136.143.2543.136.143.2554,094
1383.136.144.0/203.136.144.1 to 3.136.159.2543.136.159.2554,094
1393.136.160.0/203.136.160.1 to 3.136.175.2543.136.175.2554,094
1403.136.176.0/203.136.176.1 to 3.136.191.2543.136.191.2554,094
1413.136.192.0/203.136.192.1 to 3.136.207.2543.136.207.2554,094
1423.136.208.0/203.136.208.1 to 3.136.223.2543.136.223.2554,094
1433.136.224.0/203.136.224.1 to 3.136.239.2543.136.239.2554,094
1443.136.240.0/203.136.240.1 to 3.136.255.2543.136.255.2554,094
1453.137.0.0/203.137.0.1 to 3.137.15.2543.137.15.2554,094
1463.137.16.0/203.137.16.1 to 3.137.31.2543.137.31.2554,094
1473.137.32.0/203.137.32.1 to 3.137.47.2543.137.47.2554,094
1483.137.48.0/203.137.48.1 to 3.137.63.2543.137.63.2554,094
1493.137.64.0/203.137.64.1 to 3.137.79.2543.137.79.2554,094
1503.137.80.0/203.137.80.1 to 3.137.95.2543.137.95.2554,094
1513.137.96.0/203.137.96.1 to 3.137.111.2543.137.111.2554,094
1523.137.112.0/203.137.112.1 to 3.137.127.2543.137.127.2554,094
1533.137.128.0/203.137.128.1 to 3.137.143.2543.137.143.2554,094
1543.137.144.0/203.137.144.1 to 3.137.159.2543.137.159.2554,094
1553.137.160.0/203.137.160.1 to 3.137.175.2543.137.175.2554,094
1563.137.176.0/203.137.176.1 to 3.137.191.2543.137.191.2554,094
1573.137.192.0/203.137.192.1 to 3.137.207.2543.137.207.2554,094
1583.137.208.0/203.137.208.1 to 3.137.223.2543.137.223.2554,094
1593.137.224.0/203.137.224.1 to 3.137.239.2543.137.239.2554,094
1603.137.240.0/203.137.240.1 to 3.137.255.2543.137.255.2554,094
1613.138.0.0/203.138.0.1 to 3.138.15.2543.138.15.2554,094
1623.138.16.0/203.138.16.1 to 3.138.31.2543.138.31.2554,094
1633.138.32.0/203.138.32.1 to 3.138.47.2543.138.47.2554,094
1643.138.48.0/203.138.48.1 to 3.138.63.2543.138.63.2554,094
1653.138.64.0/203.138.64.1 to 3.138.79.2543.138.79.2554,094
1663.138.80.0/203.138.80.1 to 3.138.95.2543.138.95.2554,094
1673.138.96.0/203.138.96.1 to 3.138.111.2543.138.111.2554,094
1683.138.112.0/203.138.112.1 to 3.138.127.2543.138.127.2554,094
1693.138.128.0/203.138.128.1 to 3.138.143.2543.138.143.2554,094
1703.138.144.0/203.138.144.1 to 3.138.159.2543.138.159.2554,094
1713.138.160.0/203.138.160.1 to 3.138.175.2543.138.175.2554,094
1723.138.176.0/203.138.176.1 to 3.138.191.2543.138.191.2554,094
1733.138.192.0/203.138.192.1 to 3.138.207.2543.138.207.2554,094
1743.138.208.0/203.138.208.1 to 3.138.223.2543.138.223.2554,094
1753.138.224.0/203.138.224.1 to 3.138.239.2543.138.239.2554,094
1763.138.240.0/203.138.240.1 to 3.138.255.2543.138.255.2554,094
1773.139.0.0/203.139.0.1 to 3.139.15.2543.139.15.2554,094
1783.139.16.0/203.139.16.1 to 3.139.31.2543.139.31.2554,094
1793.139.32.0/203.139.32.1 to 3.139.47.2543.139.47.2554,094
1803.139.48.0/203.139.48.1 to 3.139.63.2543.139.63.2554,094
1813.139.64.0/203.139.64.1 to 3.139.79.2543.139.79.2554,094
1823.139.80.0/203.139.80.1 to 3.139.95.2543.139.95.2554,094
1833.139.96.0/203.139.96.1 to 3.139.111.2543.139.111.2554,094
1843.139.112.0/203.139.112.1 to 3.139.127.2543.139.127.2554,094
1853.139.128.0/203.139.128.1 to 3.139.143.2543.139.143.2554,094
1863.139.144.0/203.139.144.1 to 3.139.159.2543.139.159.2554,094
1873.139.160.0/203.139.160.1 to 3.139.175.2543.139.175.2554,094
1883.139.176.0/203.139.176.1 to 3.139.191.2543.139.191.2554,094
1893.139.192.0/203.139.192.1 to 3.139.207.2543.139.207.2554,094
1903.139.208.0/203.139.208.1 to 3.139.223.2543.139.223.2554,094
1913.139.224.0/203.139.224.1 to 3.139.239.2543.139.239.2554,094
1923.139.240.0/203.139.240.1 to 3.139.255.2543.139.255.2554,094
1933.140.0.0/203.140.0.1 to 3.140.15.2543.140.15.2554,094
1943.140.16.0/203.140.16.1 to 3.140.31.2543.140.31.2554,094
1953.140.32.0/203.140.32.1 to 3.140.47.2543.140.47.2554,094
1963.140.48.0/203.140.48.1 to 3.140.63.2543.140.63.2554,094
1973.140.64.0/203.140.64.1 to 3.140.79.2543.140.79.2554,094
1983.140.80.0/203.140.80.1 to 3.140.95.2543.140.95.2554,094
1993.140.96.0/203.140.96.1 to 3.140.111.2543.140.111.2554,094
2003.140.112.0/203.140.112.1 to 3.140.127.2543.140.127.2554,094
2013.140.128.0/203.140.128.1 to 3.140.143.2543.140.143.2554,094
2023.140.144.0/203.140.144.1 to 3.140.159.2543.140.159.2554,094
2033.140.160.0/203.140.160.1 to 3.140.175.2543.140.175.2554,094
2043.140.176.0/203.140.176.1 to 3.140.191.2543.140.191.2554,094
2053.140.192.0/203.140.192.1 to 3.140.207.2543.140.207.2554,094
2063.140.208.0/203.140.208.1 to 3.140.223.2543.140.223.2554,094
2073.140.224.0/203.140.224.1 to 3.140.239.2543.140.239.2554,094
2083.140.240.0/203.140.240.1 to 3.140.255.2543.140.255.2554,094
2093.141.0.0/203.141.0.1 to 3.141.15.2543.141.15.2554,094
2103.141.16.0/203.141.16.1 to 3.141.31.2543.141.31.2554,094
2113.141.32.0/203.141.32.1 to 3.141.47.2543.141.47.2554,094
2123.141.48.0/203.141.48.1 to 3.141.63.2543.141.63.2554,094
2133.141.64.0/203.141.64.1 to 3.141.79.2543.141.79.2554,094
2143.141.80.0/203.141.80.1 to 3.141.95.2543.141.95.2554,094
2153.141.96.0/203.141.96.1 to 3.141.111.2543.141.111.2554,094
2163.141.112.0/203.141.112.1 to 3.141.127.2543.141.127.2554,094
2173.141.128.0/203.141.128.1 to 3.141.143.2543.141.143.2554,094
2183.141.144.0/203.141.144.1 to 3.141.159.2543.141.159.2554,094
2193.141.160.0/203.141.160.1 to 3.141.175.2543.141.175.2554,094
2203.141.176.0/203.141.176.1 to 3.141.191.2543.141.191.2554,094
2213.141.192.0/203.141.192.1 to 3.141.207.2543.141.207.2554,094
2223.141.208.0/203.141.208.1 to 3.141.223.2543.141.223.2554,094
2233.141.224.0/203.141.224.1 to 3.141.239.2543.141.239.2554,094
2243.141.240.0/203.141.240.1 to 3.141.255.2543.141.255.2554,094
2253.142.0.0/203.142.0.1 to 3.142.15.2543.142.15.2554,094
2263.142.16.0/203.142.16.1 to 3.142.31.2543.142.31.2554,094
2273.142.32.0/203.142.32.1 to 3.142.47.2543.142.47.2554,094
2283.142.48.0/203.142.48.1 to 3.142.63.2543.142.63.2554,094
2293.142.64.0/203.142.64.1 to 3.142.79.2543.142.79.2554,094
2303.142.80.0/203.142.80.1 to 3.142.95.2543.142.95.2554,094
2313.142.96.0/203.142.96.1 to 3.142.111.2543.142.111.2554,094
2323.142.112.0/203.142.112.1 to 3.142.127.2543.142.127.2554,094
2333.142.128.0/203.142.128.1 to 3.142.143.2543.142.143.2554,094
2343.142.144.0/203.142.144.1 to 3.142.159.2543.142.159.2554,094
2353.142.160.0/203.142.160.1 to 3.142.175.2543.142.175.2554,094
2363.142.176.0/203.142.176.1 to 3.142.191.2543.142.191.2554,094
2373.142.192.0/203.142.192.1 to 3.142.207.2543.142.207.2554,094
2383.142.208.0/203.142.208.1 to 3.142.223.2543.142.223.2554,094
2393.142.224.0/203.142.224.1 to 3.142.239.2543.142.239.2554,094
2403.142.240.0/203.142.240.1 to 3.142.255.2543.142.255.2554,094
2413.143.0.0/203.143.0.1 to 3.143.15.2543.143.15.2554,094
2423.143.16.0/203.143.16.1 to 3.143.31.2543.143.31.2554,094
2433.143.32.0/203.143.32.1 to 3.143.47.2543.143.47.2554,094
2443.143.48.0/203.143.48.1 to 3.143.63.2543.143.63.2554,094
2453.143.64.0/203.143.64.1 to 3.143.79.2543.143.79.2554,094
2463.143.80.0/203.143.80.1 to 3.143.95.2543.143.95.2554,094
2473.143.96.0/203.143.96.1 to 3.143.111.2543.143.111.2554,094
2483.143.112.0/203.143.112.1 to 3.143.127.2543.143.127.2554,094
2493.143.128.0/203.143.128.1 to 3.143.143.2543.143.143.2554,094
2503.143.144.0/203.143.144.1 to 3.143.159.2543.143.159.2554,094
2513.143.160.0/203.143.160.1 to 3.143.175.2543.143.175.2554,094
2523.143.176.0/203.143.176.1 to 3.143.191.2543.143.191.2554,094
2533.143.192.0/203.143.192.1 to 3.143.207.2543.143.207.2554,094
2543.143.208.0/203.143.208.1 to 3.143.223.2543.143.223.2554,094
2553.143.224.0/203.143.224.1 to 3.143.239.2543.143.239.2554,094
2563.143.240.0/203.143.240.1 to 3.143.255.2543.143.255.2554,094

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.