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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.

Network2.136.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
2.136.64.0
Broadcast address
2.136.127.255
First usable
2.136.64.1
Last usable
2.136.127.254
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 02884000 · Integer 42483712 to 42500095
Reverse DNS zones
64.136.2.in-addr.arpa
65.136.2.in-addr.arpa
66.136.2.in-addr.arpa
67.136.2.in-addr.arpa
68.136.2.in-addr.arpa
69.136.2.in-addr.arpa
70.136.2.in-addr.arpa
71.136.2.in-addr.arpa
72.136.2.in-addr.arpa
73.136.2.in-addr.arpa
74.136.2.in-addr.arpa
75.136.2.in-addr.arpa
76.136.2.in-addr.arpa
77.136.2.in-addr.arpa
78.136.2.in-addr.arpa
79.136.2.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
Address00000010.10001000.01000000.000000002.136.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00000010.10001000.01000000.000000002.136.64.0
Broadcast00000010.10001000.01111111.111111112.136.127.255
Split into smaller subnets/29
/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)

2.136.64.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
12.136.64.0/292.136.64.1 to 2.136.64.62.136.64.76
22.136.64.8/292.136.64.9 to 2.136.64.142.136.64.156
32.136.64.16/292.136.64.17 to 2.136.64.222.136.64.236
42.136.64.24/292.136.64.25 to 2.136.64.302.136.64.316
52.136.64.32/292.136.64.33 to 2.136.64.382.136.64.396
62.136.64.40/292.136.64.41 to 2.136.64.462.136.64.476
72.136.64.48/292.136.64.49 to 2.136.64.542.136.64.556
82.136.64.56/292.136.64.57 to 2.136.64.622.136.64.636
92.136.64.64/292.136.64.65 to 2.136.64.702.136.64.716
102.136.64.72/292.136.64.73 to 2.136.64.782.136.64.796
112.136.64.80/292.136.64.81 to 2.136.64.862.136.64.876
122.136.64.88/292.136.64.89 to 2.136.64.942.136.64.956
132.136.64.96/292.136.64.97 to 2.136.64.1022.136.64.1036
142.136.64.104/292.136.64.105 to 2.136.64.1102.136.64.1116
152.136.64.112/292.136.64.113 to 2.136.64.1182.136.64.1196
162.136.64.120/292.136.64.121 to 2.136.64.1262.136.64.1276
172.136.64.128/292.136.64.129 to 2.136.64.1342.136.64.1356
182.136.64.136/292.136.64.137 to 2.136.64.1422.136.64.1436
192.136.64.144/292.136.64.145 to 2.136.64.1502.136.64.1516
202.136.64.152/292.136.64.153 to 2.136.64.1582.136.64.1596
212.136.64.160/292.136.64.161 to 2.136.64.1662.136.64.1676
222.136.64.168/292.136.64.169 to 2.136.64.1742.136.64.1756
232.136.64.176/292.136.64.177 to 2.136.64.1822.136.64.1836
242.136.64.184/292.136.64.185 to 2.136.64.1902.136.64.1916
252.136.64.192/292.136.64.193 to 2.136.64.1982.136.64.1996
262.136.64.200/292.136.64.201 to 2.136.64.2062.136.64.2076
272.136.64.208/292.136.64.209 to 2.136.64.2142.136.64.2156
282.136.64.216/292.136.64.217 to 2.136.64.2222.136.64.2236
292.136.64.224/292.136.64.225 to 2.136.64.2302.136.64.2316
302.136.64.232/292.136.64.233 to 2.136.64.2382.136.64.2396
312.136.64.240/292.136.64.241 to 2.136.64.2462.136.64.2476
322.136.64.248/292.136.64.249 to 2.136.64.2542.136.64.2556
332.136.65.0/292.136.65.1 to 2.136.65.62.136.65.76
342.136.65.8/292.136.65.9 to 2.136.65.142.136.65.156
352.136.65.16/292.136.65.17 to 2.136.65.222.136.65.236
362.136.65.24/292.136.65.25 to 2.136.65.302.136.65.316
372.136.65.32/292.136.65.33 to 2.136.65.382.136.65.396
382.136.65.40/292.136.65.41 to 2.136.65.462.136.65.476
392.136.65.48/292.136.65.49 to 2.136.65.542.136.65.556
402.136.65.56/292.136.65.57 to 2.136.65.622.136.65.636
412.136.65.64/292.136.65.65 to 2.136.65.702.136.65.716
422.136.65.72/292.136.65.73 to 2.136.65.782.136.65.796
432.136.65.80/292.136.65.81 to 2.136.65.862.136.65.876
442.136.65.88/292.136.65.89 to 2.136.65.942.136.65.956
452.136.65.96/292.136.65.97 to 2.136.65.1022.136.65.1036
462.136.65.104/292.136.65.105 to 2.136.65.1102.136.65.1116
472.136.65.112/292.136.65.113 to 2.136.65.1182.136.65.1196
482.136.65.120/292.136.65.121 to 2.136.65.1262.136.65.1276
492.136.65.128/292.136.65.129 to 2.136.65.1342.136.65.1356
502.136.65.136/292.136.65.137 to 2.136.65.1422.136.65.1436
512.136.65.144/292.136.65.145 to 2.136.65.1502.136.65.1516
522.136.65.152/292.136.65.153 to 2.136.65.1582.136.65.1596
532.136.65.160/292.136.65.161 to 2.136.65.1662.136.65.1676
542.136.65.168/292.136.65.169 to 2.136.65.1742.136.65.1756
552.136.65.176/292.136.65.177 to 2.136.65.1822.136.65.1836
562.136.65.184/292.136.65.185 to 2.136.65.1902.136.65.1916
572.136.65.192/292.136.65.193 to 2.136.65.1982.136.65.1996
582.136.65.200/292.136.65.201 to 2.136.65.2062.136.65.2076
592.136.65.208/292.136.65.209 to 2.136.65.2142.136.65.2156
602.136.65.216/292.136.65.217 to 2.136.65.2222.136.65.2236
612.136.65.224/292.136.65.225 to 2.136.65.2302.136.65.2316
622.136.65.232/292.136.65.233 to 2.136.65.2382.136.65.2396
632.136.65.240/292.136.65.241 to 2.136.65.2462.136.65.2476
642.136.65.248/292.136.65.249 to 2.136.65.2542.136.65.2556
652.136.66.0/292.136.66.1 to 2.136.66.62.136.66.76
662.136.66.8/292.136.66.9 to 2.136.66.142.136.66.156
672.136.66.16/292.136.66.17 to 2.136.66.222.136.66.236
682.136.66.24/292.136.66.25 to 2.136.66.302.136.66.316
692.136.66.32/292.136.66.33 to 2.136.66.382.136.66.396
702.136.66.40/292.136.66.41 to 2.136.66.462.136.66.476
712.136.66.48/292.136.66.49 to 2.136.66.542.136.66.556
722.136.66.56/292.136.66.57 to 2.136.66.622.136.66.636
732.136.66.64/292.136.66.65 to 2.136.66.702.136.66.716
742.136.66.72/292.136.66.73 to 2.136.66.782.136.66.796
752.136.66.80/292.136.66.81 to 2.136.66.862.136.66.876
762.136.66.88/292.136.66.89 to 2.136.66.942.136.66.956
772.136.66.96/292.136.66.97 to 2.136.66.1022.136.66.1036
782.136.66.104/292.136.66.105 to 2.136.66.1102.136.66.1116
792.136.66.112/292.136.66.113 to 2.136.66.1182.136.66.1196
802.136.66.120/292.136.66.121 to 2.136.66.1262.136.66.1276
812.136.66.128/292.136.66.129 to 2.136.66.1342.136.66.1356
822.136.66.136/292.136.66.137 to 2.136.66.1422.136.66.1436
832.136.66.144/292.136.66.145 to 2.136.66.1502.136.66.1516
842.136.66.152/292.136.66.153 to 2.136.66.1582.136.66.1596
852.136.66.160/292.136.66.161 to 2.136.66.1662.136.66.1676
862.136.66.168/292.136.66.169 to 2.136.66.1742.136.66.1756
872.136.66.176/292.136.66.177 to 2.136.66.1822.136.66.1836
882.136.66.184/292.136.66.185 to 2.136.66.1902.136.66.1916
892.136.66.192/292.136.66.193 to 2.136.66.1982.136.66.1996
902.136.66.200/292.136.66.201 to 2.136.66.2062.136.66.2076
912.136.66.208/292.136.66.209 to 2.136.66.2142.136.66.2156
922.136.66.216/292.136.66.217 to 2.136.66.2222.136.66.2236
932.136.66.224/292.136.66.225 to 2.136.66.2302.136.66.2316
942.136.66.232/292.136.66.233 to 2.136.66.2382.136.66.2396
952.136.66.240/292.136.66.241 to 2.136.66.2462.136.66.2476
962.136.66.248/292.136.66.249 to 2.136.66.2542.136.66.2556
972.136.67.0/292.136.67.1 to 2.136.67.62.136.67.76
982.136.67.8/292.136.67.9 to 2.136.67.142.136.67.156
992.136.67.16/292.136.67.17 to 2.136.67.222.136.67.236
1002.136.67.24/292.136.67.25 to 2.136.67.302.136.67.316
1012.136.67.32/292.136.67.33 to 2.136.67.382.136.67.396
1022.136.67.40/292.136.67.41 to 2.136.67.462.136.67.476
1032.136.67.48/292.136.67.49 to 2.136.67.542.136.67.556
1042.136.67.56/292.136.67.57 to 2.136.67.622.136.67.636
1052.136.67.64/292.136.67.65 to 2.136.67.702.136.67.716
1062.136.67.72/292.136.67.73 to 2.136.67.782.136.67.796
1072.136.67.80/292.136.67.81 to 2.136.67.862.136.67.876
1082.136.67.88/292.136.67.89 to 2.136.67.942.136.67.956
1092.136.67.96/292.136.67.97 to 2.136.67.1022.136.67.1036
1102.136.67.104/292.136.67.105 to 2.136.67.1102.136.67.1116
1112.136.67.112/292.136.67.113 to 2.136.67.1182.136.67.1196
1122.136.67.120/292.136.67.121 to 2.136.67.1262.136.67.1276
1132.136.67.128/292.136.67.129 to 2.136.67.1342.136.67.1356
1142.136.67.136/292.136.67.137 to 2.136.67.1422.136.67.1436
1152.136.67.144/292.136.67.145 to 2.136.67.1502.136.67.1516
1162.136.67.152/292.136.67.153 to 2.136.67.1582.136.67.1596
1172.136.67.160/292.136.67.161 to 2.136.67.1662.136.67.1676
1182.136.67.168/292.136.67.169 to 2.136.67.1742.136.67.1756
1192.136.67.176/292.136.67.177 to 2.136.67.1822.136.67.1836
1202.136.67.184/292.136.67.185 to 2.136.67.1902.136.67.1916
1212.136.67.192/292.136.67.193 to 2.136.67.1982.136.67.1996
1222.136.67.200/292.136.67.201 to 2.136.67.2062.136.67.2076
1232.136.67.208/292.136.67.209 to 2.136.67.2142.136.67.2156
1242.136.67.216/292.136.67.217 to 2.136.67.2222.136.67.2236
1252.136.67.224/292.136.67.225 to 2.136.67.2302.136.67.2316
1262.136.67.232/292.136.67.233 to 2.136.67.2382.136.67.2396
1272.136.67.240/292.136.67.241 to 2.136.67.2462.136.67.2476
1282.136.67.248/292.136.67.249 to 2.136.67.2542.136.67.2556
1292.136.68.0/292.136.68.1 to 2.136.68.62.136.68.76
1302.136.68.8/292.136.68.9 to 2.136.68.142.136.68.156
1312.136.68.16/292.136.68.17 to 2.136.68.222.136.68.236
1322.136.68.24/292.136.68.25 to 2.136.68.302.136.68.316
1332.136.68.32/292.136.68.33 to 2.136.68.382.136.68.396
1342.136.68.40/292.136.68.41 to 2.136.68.462.136.68.476
1352.136.68.48/292.136.68.49 to 2.136.68.542.136.68.556
1362.136.68.56/292.136.68.57 to 2.136.68.622.136.68.636
1372.136.68.64/292.136.68.65 to 2.136.68.702.136.68.716
1382.136.68.72/292.136.68.73 to 2.136.68.782.136.68.796
1392.136.68.80/292.136.68.81 to 2.136.68.862.136.68.876
1402.136.68.88/292.136.68.89 to 2.136.68.942.136.68.956
1412.136.68.96/292.136.68.97 to 2.136.68.1022.136.68.1036
1422.136.68.104/292.136.68.105 to 2.136.68.1102.136.68.1116
1432.136.68.112/292.136.68.113 to 2.136.68.1182.136.68.1196
1442.136.68.120/292.136.68.121 to 2.136.68.1262.136.68.1276
1452.136.68.128/292.136.68.129 to 2.136.68.1342.136.68.1356
1462.136.68.136/292.136.68.137 to 2.136.68.1422.136.68.1436
1472.136.68.144/292.136.68.145 to 2.136.68.1502.136.68.1516
1482.136.68.152/292.136.68.153 to 2.136.68.1582.136.68.1596
1492.136.68.160/292.136.68.161 to 2.136.68.1662.136.68.1676
1502.136.68.168/292.136.68.169 to 2.136.68.1742.136.68.1756
1512.136.68.176/292.136.68.177 to 2.136.68.1822.136.68.1836
1522.136.68.184/292.136.68.185 to 2.136.68.1902.136.68.1916
1532.136.68.192/292.136.68.193 to 2.136.68.1982.136.68.1996
1542.136.68.200/292.136.68.201 to 2.136.68.2062.136.68.2076
1552.136.68.208/292.136.68.209 to 2.136.68.2142.136.68.2156
1562.136.68.216/292.136.68.217 to 2.136.68.2222.136.68.2236
1572.136.68.224/292.136.68.225 to 2.136.68.2302.136.68.2316
1582.136.68.232/292.136.68.233 to 2.136.68.2382.136.68.2396
1592.136.68.240/292.136.68.241 to 2.136.68.2462.136.68.2476
1602.136.68.248/292.136.68.249 to 2.136.68.2542.136.68.2556
1612.136.69.0/292.136.69.1 to 2.136.69.62.136.69.76
1622.136.69.8/292.136.69.9 to 2.136.69.142.136.69.156
1632.136.69.16/292.136.69.17 to 2.136.69.222.136.69.236
1642.136.69.24/292.136.69.25 to 2.136.69.302.136.69.316
1652.136.69.32/292.136.69.33 to 2.136.69.382.136.69.396
1662.136.69.40/292.136.69.41 to 2.136.69.462.136.69.476
1672.136.69.48/292.136.69.49 to 2.136.69.542.136.69.556
1682.136.69.56/292.136.69.57 to 2.136.69.622.136.69.636
1692.136.69.64/292.136.69.65 to 2.136.69.702.136.69.716
1702.136.69.72/292.136.69.73 to 2.136.69.782.136.69.796
1712.136.69.80/292.136.69.81 to 2.136.69.862.136.69.876
1722.136.69.88/292.136.69.89 to 2.136.69.942.136.69.956
1732.136.69.96/292.136.69.97 to 2.136.69.1022.136.69.1036
1742.136.69.104/292.136.69.105 to 2.136.69.1102.136.69.1116
1752.136.69.112/292.136.69.113 to 2.136.69.1182.136.69.1196
1762.136.69.120/292.136.69.121 to 2.136.69.1262.136.69.1276
1772.136.69.128/292.136.69.129 to 2.136.69.1342.136.69.1356
1782.136.69.136/292.136.69.137 to 2.136.69.1422.136.69.1436
1792.136.69.144/292.136.69.145 to 2.136.69.1502.136.69.1516
1802.136.69.152/292.136.69.153 to 2.136.69.1582.136.69.1596
1812.136.69.160/292.136.69.161 to 2.136.69.1662.136.69.1676
1822.136.69.168/292.136.69.169 to 2.136.69.1742.136.69.1756
1832.136.69.176/292.136.69.177 to 2.136.69.1822.136.69.1836
1842.136.69.184/292.136.69.185 to 2.136.69.1902.136.69.1916
1852.136.69.192/292.136.69.193 to 2.136.69.1982.136.69.1996
1862.136.69.200/292.136.69.201 to 2.136.69.2062.136.69.2076
1872.136.69.208/292.136.69.209 to 2.136.69.2142.136.69.2156
1882.136.69.216/292.136.69.217 to 2.136.69.2222.136.69.2236
1892.136.69.224/292.136.69.225 to 2.136.69.2302.136.69.2316
1902.136.69.232/292.136.69.233 to 2.136.69.2382.136.69.2396
1912.136.69.240/292.136.69.241 to 2.136.69.2462.136.69.2476
1922.136.69.248/292.136.69.249 to 2.136.69.2542.136.69.2556
1932.136.70.0/292.136.70.1 to 2.136.70.62.136.70.76
1942.136.70.8/292.136.70.9 to 2.136.70.142.136.70.156
1952.136.70.16/292.136.70.17 to 2.136.70.222.136.70.236
1962.136.70.24/292.136.70.25 to 2.136.70.302.136.70.316
1972.136.70.32/292.136.70.33 to 2.136.70.382.136.70.396
1982.136.70.40/292.136.70.41 to 2.136.70.462.136.70.476
1992.136.70.48/292.136.70.49 to 2.136.70.542.136.70.556
2002.136.70.56/292.136.70.57 to 2.136.70.622.136.70.636
2012.136.70.64/292.136.70.65 to 2.136.70.702.136.70.716
2022.136.70.72/292.136.70.73 to 2.136.70.782.136.70.796
2032.136.70.80/292.136.70.81 to 2.136.70.862.136.70.876
2042.136.70.88/292.136.70.89 to 2.136.70.942.136.70.956
2052.136.70.96/292.136.70.97 to 2.136.70.1022.136.70.1036
2062.136.70.104/292.136.70.105 to 2.136.70.1102.136.70.1116
2072.136.70.112/292.136.70.113 to 2.136.70.1182.136.70.1196
2082.136.70.120/292.136.70.121 to 2.136.70.1262.136.70.1276
2092.136.70.128/292.136.70.129 to 2.136.70.1342.136.70.1356
2102.136.70.136/292.136.70.137 to 2.136.70.1422.136.70.1436
2112.136.70.144/292.136.70.145 to 2.136.70.1502.136.70.1516
2122.136.70.152/292.136.70.153 to 2.136.70.1582.136.70.1596
2132.136.70.160/292.136.70.161 to 2.136.70.1662.136.70.1676
2142.136.70.168/292.136.70.169 to 2.136.70.1742.136.70.1756
2152.136.70.176/292.136.70.177 to 2.136.70.1822.136.70.1836
2162.136.70.184/292.136.70.185 to 2.136.70.1902.136.70.1916
2172.136.70.192/292.136.70.193 to 2.136.70.1982.136.70.1996
2182.136.70.200/292.136.70.201 to 2.136.70.2062.136.70.2076
2192.136.70.208/292.136.70.209 to 2.136.70.2142.136.70.2156
2202.136.70.216/292.136.70.217 to 2.136.70.2222.136.70.2236
2212.136.70.224/292.136.70.225 to 2.136.70.2302.136.70.2316
2222.136.70.232/292.136.70.233 to 2.136.70.2382.136.70.2396
2232.136.70.240/292.136.70.241 to 2.136.70.2462.136.70.2476
2242.136.70.248/292.136.70.249 to 2.136.70.2542.136.70.2556
2252.136.71.0/292.136.71.1 to 2.136.71.62.136.71.76
2262.136.71.8/292.136.71.9 to 2.136.71.142.136.71.156
2272.136.71.16/292.136.71.17 to 2.136.71.222.136.71.236
2282.136.71.24/292.136.71.25 to 2.136.71.302.136.71.316
2292.136.71.32/292.136.71.33 to 2.136.71.382.136.71.396
2302.136.71.40/292.136.71.41 to 2.136.71.462.136.71.476
2312.136.71.48/292.136.71.49 to 2.136.71.542.136.71.556
2322.136.71.56/292.136.71.57 to 2.136.71.622.136.71.636
2332.136.71.64/292.136.71.65 to 2.136.71.702.136.71.716
2342.136.71.72/292.136.71.73 to 2.136.71.782.136.71.796
2352.136.71.80/292.136.71.81 to 2.136.71.862.136.71.876
2362.136.71.88/292.136.71.89 to 2.136.71.942.136.71.956
2372.136.71.96/292.136.71.97 to 2.136.71.1022.136.71.1036
2382.136.71.104/292.136.71.105 to 2.136.71.1102.136.71.1116
2392.136.71.112/292.136.71.113 to 2.136.71.1182.136.71.1196
2402.136.71.120/292.136.71.121 to 2.136.71.1262.136.71.1276
2412.136.71.128/292.136.71.129 to 2.136.71.1342.136.71.1356
2422.136.71.136/292.136.71.137 to 2.136.71.1422.136.71.1436
2432.136.71.144/292.136.71.145 to 2.136.71.1502.136.71.1516
2442.136.71.152/292.136.71.153 to 2.136.71.1582.136.71.1596
2452.136.71.160/292.136.71.161 to 2.136.71.1662.136.71.1676
2462.136.71.168/292.136.71.169 to 2.136.71.1742.136.71.1756
2472.136.71.176/292.136.71.177 to 2.136.71.1822.136.71.1836
2482.136.71.184/292.136.71.185 to 2.136.71.1902.136.71.1916
2492.136.71.192/292.136.71.193 to 2.136.71.1982.136.71.1996
2502.136.71.200/292.136.71.201 to 2.136.71.2062.136.71.2076
2512.136.71.208/292.136.71.209 to 2.136.71.2142.136.71.2156
2522.136.71.216/292.136.71.217 to 2.136.71.2222.136.71.2236
2532.136.71.224/292.136.71.225 to 2.136.71.2302.136.71.2316
2542.136.71.232/292.136.71.233 to 2.136.71.2382.136.71.2396
2552.136.71.240/292.136.71.241 to 2.136.71.2462.136.71.2476
2562.136.71.248/292.136.71.249 to 2.136.71.2542.136.71.2556

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.