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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.

Network8.57.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
8.57.0.0
Broadcast address
8.57.63.255
First usable
8.57.0.1
Last usable
8.57.63.254
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 08390000 · Integer 137953280 to 137969663
Reverse DNS zones
0.57.8.in-addr.arpa
1.57.8.in-addr.arpa
2.57.8.in-addr.arpa
3.57.8.in-addr.arpa
4.57.8.in-addr.arpa
5.57.8.in-addr.arpa
6.57.8.in-addr.arpa
7.57.8.in-addr.arpa
8.57.8.in-addr.arpa
9.57.8.in-addr.arpa
10.57.8.in-addr.arpa
11.57.8.in-addr.arpa
12.57.8.in-addr.arpa
13.57.8.in-addr.arpa
14.57.8.in-addr.arpa
15.57.8.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
Address00001000.00111001.00000000.000000008.57.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00001000.00111001.00000000.000000008.57.0.0
Broadcast00001000.00111001.00111111.111111118.57.63.255
Split into smaller subnets/27
/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)

8.57.0.0/18 makes 512 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
18.57.0.0/278.57.0.1 to 8.57.0.308.57.0.3130
28.57.0.32/278.57.0.33 to 8.57.0.628.57.0.6330
38.57.0.64/278.57.0.65 to 8.57.0.948.57.0.9530
48.57.0.96/278.57.0.97 to 8.57.0.1268.57.0.12730
58.57.0.128/278.57.0.129 to 8.57.0.1588.57.0.15930
68.57.0.160/278.57.0.161 to 8.57.0.1908.57.0.19130
78.57.0.192/278.57.0.193 to 8.57.0.2228.57.0.22330
88.57.0.224/278.57.0.225 to 8.57.0.2548.57.0.25530
98.57.1.0/278.57.1.1 to 8.57.1.308.57.1.3130
108.57.1.32/278.57.1.33 to 8.57.1.628.57.1.6330
118.57.1.64/278.57.1.65 to 8.57.1.948.57.1.9530
128.57.1.96/278.57.1.97 to 8.57.1.1268.57.1.12730
138.57.1.128/278.57.1.129 to 8.57.1.1588.57.1.15930
148.57.1.160/278.57.1.161 to 8.57.1.1908.57.1.19130
158.57.1.192/278.57.1.193 to 8.57.1.2228.57.1.22330
168.57.1.224/278.57.1.225 to 8.57.1.2548.57.1.25530
178.57.2.0/278.57.2.1 to 8.57.2.308.57.2.3130
188.57.2.32/278.57.2.33 to 8.57.2.628.57.2.6330
198.57.2.64/278.57.2.65 to 8.57.2.948.57.2.9530
208.57.2.96/278.57.2.97 to 8.57.2.1268.57.2.12730
218.57.2.128/278.57.2.129 to 8.57.2.1588.57.2.15930
228.57.2.160/278.57.2.161 to 8.57.2.1908.57.2.19130
238.57.2.192/278.57.2.193 to 8.57.2.2228.57.2.22330
248.57.2.224/278.57.2.225 to 8.57.2.2548.57.2.25530
258.57.3.0/278.57.3.1 to 8.57.3.308.57.3.3130
268.57.3.32/278.57.3.33 to 8.57.3.628.57.3.6330
278.57.3.64/278.57.3.65 to 8.57.3.948.57.3.9530
288.57.3.96/278.57.3.97 to 8.57.3.1268.57.3.12730
298.57.3.128/278.57.3.129 to 8.57.3.1588.57.3.15930
308.57.3.160/278.57.3.161 to 8.57.3.1908.57.3.19130
318.57.3.192/278.57.3.193 to 8.57.3.2228.57.3.22330
328.57.3.224/278.57.3.225 to 8.57.3.2548.57.3.25530
338.57.4.0/278.57.4.1 to 8.57.4.308.57.4.3130
348.57.4.32/278.57.4.33 to 8.57.4.628.57.4.6330
358.57.4.64/278.57.4.65 to 8.57.4.948.57.4.9530
368.57.4.96/278.57.4.97 to 8.57.4.1268.57.4.12730
378.57.4.128/278.57.4.129 to 8.57.4.1588.57.4.15930
388.57.4.160/278.57.4.161 to 8.57.4.1908.57.4.19130
398.57.4.192/278.57.4.193 to 8.57.4.2228.57.4.22330
408.57.4.224/278.57.4.225 to 8.57.4.2548.57.4.25530
418.57.5.0/278.57.5.1 to 8.57.5.308.57.5.3130
428.57.5.32/278.57.5.33 to 8.57.5.628.57.5.6330
438.57.5.64/278.57.5.65 to 8.57.5.948.57.5.9530
448.57.5.96/278.57.5.97 to 8.57.5.1268.57.5.12730
458.57.5.128/278.57.5.129 to 8.57.5.1588.57.5.15930
468.57.5.160/278.57.5.161 to 8.57.5.1908.57.5.19130
478.57.5.192/278.57.5.193 to 8.57.5.2228.57.5.22330
488.57.5.224/278.57.5.225 to 8.57.5.2548.57.5.25530
498.57.6.0/278.57.6.1 to 8.57.6.308.57.6.3130
508.57.6.32/278.57.6.33 to 8.57.6.628.57.6.6330
518.57.6.64/278.57.6.65 to 8.57.6.948.57.6.9530
528.57.6.96/278.57.6.97 to 8.57.6.1268.57.6.12730
538.57.6.128/278.57.6.129 to 8.57.6.1588.57.6.15930
548.57.6.160/278.57.6.161 to 8.57.6.1908.57.6.19130
558.57.6.192/278.57.6.193 to 8.57.6.2228.57.6.22330
568.57.6.224/278.57.6.225 to 8.57.6.2548.57.6.25530
578.57.7.0/278.57.7.1 to 8.57.7.308.57.7.3130
588.57.7.32/278.57.7.33 to 8.57.7.628.57.7.6330
598.57.7.64/278.57.7.65 to 8.57.7.948.57.7.9530
608.57.7.96/278.57.7.97 to 8.57.7.1268.57.7.12730
618.57.7.128/278.57.7.129 to 8.57.7.1588.57.7.15930
628.57.7.160/278.57.7.161 to 8.57.7.1908.57.7.19130
638.57.7.192/278.57.7.193 to 8.57.7.2228.57.7.22330
648.57.7.224/278.57.7.225 to 8.57.7.2548.57.7.25530
658.57.8.0/278.57.8.1 to 8.57.8.308.57.8.3130
668.57.8.32/278.57.8.33 to 8.57.8.628.57.8.6330
678.57.8.64/278.57.8.65 to 8.57.8.948.57.8.9530
688.57.8.96/278.57.8.97 to 8.57.8.1268.57.8.12730
698.57.8.128/278.57.8.129 to 8.57.8.1588.57.8.15930
708.57.8.160/278.57.8.161 to 8.57.8.1908.57.8.19130
718.57.8.192/278.57.8.193 to 8.57.8.2228.57.8.22330
728.57.8.224/278.57.8.225 to 8.57.8.2548.57.8.25530
738.57.9.0/278.57.9.1 to 8.57.9.308.57.9.3130
748.57.9.32/278.57.9.33 to 8.57.9.628.57.9.6330
758.57.9.64/278.57.9.65 to 8.57.9.948.57.9.9530
768.57.9.96/278.57.9.97 to 8.57.9.1268.57.9.12730
778.57.9.128/278.57.9.129 to 8.57.9.1588.57.9.15930
788.57.9.160/278.57.9.161 to 8.57.9.1908.57.9.19130
798.57.9.192/278.57.9.193 to 8.57.9.2228.57.9.22330
808.57.9.224/278.57.9.225 to 8.57.9.2548.57.9.25530
818.57.10.0/278.57.10.1 to 8.57.10.308.57.10.3130
828.57.10.32/278.57.10.33 to 8.57.10.628.57.10.6330
838.57.10.64/278.57.10.65 to 8.57.10.948.57.10.9530
848.57.10.96/278.57.10.97 to 8.57.10.1268.57.10.12730
858.57.10.128/278.57.10.129 to 8.57.10.1588.57.10.15930
868.57.10.160/278.57.10.161 to 8.57.10.1908.57.10.19130
878.57.10.192/278.57.10.193 to 8.57.10.2228.57.10.22330
888.57.10.224/278.57.10.225 to 8.57.10.2548.57.10.25530
898.57.11.0/278.57.11.1 to 8.57.11.308.57.11.3130
908.57.11.32/278.57.11.33 to 8.57.11.628.57.11.6330
918.57.11.64/278.57.11.65 to 8.57.11.948.57.11.9530
928.57.11.96/278.57.11.97 to 8.57.11.1268.57.11.12730
938.57.11.128/278.57.11.129 to 8.57.11.1588.57.11.15930
948.57.11.160/278.57.11.161 to 8.57.11.1908.57.11.19130
958.57.11.192/278.57.11.193 to 8.57.11.2228.57.11.22330
968.57.11.224/278.57.11.225 to 8.57.11.2548.57.11.25530
978.57.12.0/278.57.12.1 to 8.57.12.308.57.12.3130
988.57.12.32/278.57.12.33 to 8.57.12.628.57.12.6330
998.57.12.64/278.57.12.65 to 8.57.12.948.57.12.9530
1008.57.12.96/278.57.12.97 to 8.57.12.1268.57.12.12730
1018.57.12.128/278.57.12.129 to 8.57.12.1588.57.12.15930
1028.57.12.160/278.57.12.161 to 8.57.12.1908.57.12.19130
1038.57.12.192/278.57.12.193 to 8.57.12.2228.57.12.22330
1048.57.12.224/278.57.12.225 to 8.57.12.2548.57.12.25530
1058.57.13.0/278.57.13.1 to 8.57.13.308.57.13.3130
1068.57.13.32/278.57.13.33 to 8.57.13.628.57.13.6330
1078.57.13.64/278.57.13.65 to 8.57.13.948.57.13.9530
1088.57.13.96/278.57.13.97 to 8.57.13.1268.57.13.12730
1098.57.13.128/278.57.13.129 to 8.57.13.1588.57.13.15930
1108.57.13.160/278.57.13.161 to 8.57.13.1908.57.13.19130
1118.57.13.192/278.57.13.193 to 8.57.13.2228.57.13.22330
1128.57.13.224/278.57.13.225 to 8.57.13.2548.57.13.25530
1138.57.14.0/278.57.14.1 to 8.57.14.308.57.14.3130
1148.57.14.32/278.57.14.33 to 8.57.14.628.57.14.6330
1158.57.14.64/278.57.14.65 to 8.57.14.948.57.14.9530
1168.57.14.96/278.57.14.97 to 8.57.14.1268.57.14.12730
1178.57.14.128/278.57.14.129 to 8.57.14.1588.57.14.15930
1188.57.14.160/278.57.14.161 to 8.57.14.1908.57.14.19130
1198.57.14.192/278.57.14.193 to 8.57.14.2228.57.14.22330
1208.57.14.224/278.57.14.225 to 8.57.14.2548.57.14.25530
1218.57.15.0/278.57.15.1 to 8.57.15.308.57.15.3130
1228.57.15.32/278.57.15.33 to 8.57.15.628.57.15.6330
1238.57.15.64/278.57.15.65 to 8.57.15.948.57.15.9530
1248.57.15.96/278.57.15.97 to 8.57.15.1268.57.15.12730
1258.57.15.128/278.57.15.129 to 8.57.15.1588.57.15.15930
1268.57.15.160/278.57.15.161 to 8.57.15.1908.57.15.19130
1278.57.15.192/278.57.15.193 to 8.57.15.2228.57.15.22330
1288.57.15.224/278.57.15.225 to 8.57.15.2548.57.15.25530
1298.57.16.0/278.57.16.1 to 8.57.16.308.57.16.3130
1308.57.16.32/278.57.16.33 to 8.57.16.628.57.16.6330
1318.57.16.64/278.57.16.65 to 8.57.16.948.57.16.9530
1328.57.16.96/278.57.16.97 to 8.57.16.1268.57.16.12730
1338.57.16.128/278.57.16.129 to 8.57.16.1588.57.16.15930
1348.57.16.160/278.57.16.161 to 8.57.16.1908.57.16.19130
1358.57.16.192/278.57.16.193 to 8.57.16.2228.57.16.22330
1368.57.16.224/278.57.16.225 to 8.57.16.2548.57.16.25530
1378.57.17.0/278.57.17.1 to 8.57.17.308.57.17.3130
1388.57.17.32/278.57.17.33 to 8.57.17.628.57.17.6330
1398.57.17.64/278.57.17.65 to 8.57.17.948.57.17.9530
1408.57.17.96/278.57.17.97 to 8.57.17.1268.57.17.12730
1418.57.17.128/278.57.17.129 to 8.57.17.1588.57.17.15930
1428.57.17.160/278.57.17.161 to 8.57.17.1908.57.17.19130
1438.57.17.192/278.57.17.193 to 8.57.17.2228.57.17.22330
1448.57.17.224/278.57.17.225 to 8.57.17.2548.57.17.25530
1458.57.18.0/278.57.18.1 to 8.57.18.308.57.18.3130
1468.57.18.32/278.57.18.33 to 8.57.18.628.57.18.6330
1478.57.18.64/278.57.18.65 to 8.57.18.948.57.18.9530
1488.57.18.96/278.57.18.97 to 8.57.18.1268.57.18.12730
1498.57.18.128/278.57.18.129 to 8.57.18.1588.57.18.15930
1508.57.18.160/278.57.18.161 to 8.57.18.1908.57.18.19130
1518.57.18.192/278.57.18.193 to 8.57.18.2228.57.18.22330
1528.57.18.224/278.57.18.225 to 8.57.18.2548.57.18.25530
1538.57.19.0/278.57.19.1 to 8.57.19.308.57.19.3130
1548.57.19.32/278.57.19.33 to 8.57.19.628.57.19.6330
1558.57.19.64/278.57.19.65 to 8.57.19.948.57.19.9530
1568.57.19.96/278.57.19.97 to 8.57.19.1268.57.19.12730
1578.57.19.128/278.57.19.129 to 8.57.19.1588.57.19.15930
1588.57.19.160/278.57.19.161 to 8.57.19.1908.57.19.19130
1598.57.19.192/278.57.19.193 to 8.57.19.2228.57.19.22330
1608.57.19.224/278.57.19.225 to 8.57.19.2548.57.19.25530
1618.57.20.0/278.57.20.1 to 8.57.20.308.57.20.3130
1628.57.20.32/278.57.20.33 to 8.57.20.628.57.20.6330
1638.57.20.64/278.57.20.65 to 8.57.20.948.57.20.9530
1648.57.20.96/278.57.20.97 to 8.57.20.1268.57.20.12730
1658.57.20.128/278.57.20.129 to 8.57.20.1588.57.20.15930
1668.57.20.160/278.57.20.161 to 8.57.20.1908.57.20.19130
1678.57.20.192/278.57.20.193 to 8.57.20.2228.57.20.22330
1688.57.20.224/278.57.20.225 to 8.57.20.2548.57.20.25530
1698.57.21.0/278.57.21.1 to 8.57.21.308.57.21.3130
1708.57.21.32/278.57.21.33 to 8.57.21.628.57.21.6330
1718.57.21.64/278.57.21.65 to 8.57.21.948.57.21.9530
1728.57.21.96/278.57.21.97 to 8.57.21.1268.57.21.12730
1738.57.21.128/278.57.21.129 to 8.57.21.1588.57.21.15930
1748.57.21.160/278.57.21.161 to 8.57.21.1908.57.21.19130
1758.57.21.192/278.57.21.193 to 8.57.21.2228.57.21.22330
1768.57.21.224/278.57.21.225 to 8.57.21.2548.57.21.25530
1778.57.22.0/278.57.22.1 to 8.57.22.308.57.22.3130
1788.57.22.32/278.57.22.33 to 8.57.22.628.57.22.6330
1798.57.22.64/278.57.22.65 to 8.57.22.948.57.22.9530
1808.57.22.96/278.57.22.97 to 8.57.22.1268.57.22.12730
1818.57.22.128/278.57.22.129 to 8.57.22.1588.57.22.15930
1828.57.22.160/278.57.22.161 to 8.57.22.1908.57.22.19130
1838.57.22.192/278.57.22.193 to 8.57.22.2228.57.22.22330
1848.57.22.224/278.57.22.225 to 8.57.22.2548.57.22.25530
1858.57.23.0/278.57.23.1 to 8.57.23.308.57.23.3130
1868.57.23.32/278.57.23.33 to 8.57.23.628.57.23.6330
1878.57.23.64/278.57.23.65 to 8.57.23.948.57.23.9530
1888.57.23.96/278.57.23.97 to 8.57.23.1268.57.23.12730
1898.57.23.128/278.57.23.129 to 8.57.23.1588.57.23.15930
1908.57.23.160/278.57.23.161 to 8.57.23.1908.57.23.19130
1918.57.23.192/278.57.23.193 to 8.57.23.2228.57.23.22330
1928.57.23.224/278.57.23.225 to 8.57.23.2548.57.23.25530
1938.57.24.0/278.57.24.1 to 8.57.24.308.57.24.3130
1948.57.24.32/278.57.24.33 to 8.57.24.628.57.24.6330
1958.57.24.64/278.57.24.65 to 8.57.24.948.57.24.9530
1968.57.24.96/278.57.24.97 to 8.57.24.1268.57.24.12730
1978.57.24.128/278.57.24.129 to 8.57.24.1588.57.24.15930
1988.57.24.160/278.57.24.161 to 8.57.24.1908.57.24.19130
1998.57.24.192/278.57.24.193 to 8.57.24.2228.57.24.22330
2008.57.24.224/278.57.24.225 to 8.57.24.2548.57.24.25530
2018.57.25.0/278.57.25.1 to 8.57.25.308.57.25.3130
2028.57.25.32/278.57.25.33 to 8.57.25.628.57.25.6330
2038.57.25.64/278.57.25.65 to 8.57.25.948.57.25.9530
2048.57.25.96/278.57.25.97 to 8.57.25.1268.57.25.12730
2058.57.25.128/278.57.25.129 to 8.57.25.1588.57.25.15930
2068.57.25.160/278.57.25.161 to 8.57.25.1908.57.25.19130
2078.57.25.192/278.57.25.193 to 8.57.25.2228.57.25.22330
2088.57.25.224/278.57.25.225 to 8.57.25.2548.57.25.25530
2098.57.26.0/278.57.26.1 to 8.57.26.308.57.26.3130
2108.57.26.32/278.57.26.33 to 8.57.26.628.57.26.6330
2118.57.26.64/278.57.26.65 to 8.57.26.948.57.26.9530
2128.57.26.96/278.57.26.97 to 8.57.26.1268.57.26.12730
2138.57.26.128/278.57.26.129 to 8.57.26.1588.57.26.15930
2148.57.26.160/278.57.26.161 to 8.57.26.1908.57.26.19130
2158.57.26.192/278.57.26.193 to 8.57.26.2228.57.26.22330
2168.57.26.224/278.57.26.225 to 8.57.26.2548.57.26.25530
2178.57.27.0/278.57.27.1 to 8.57.27.308.57.27.3130
2188.57.27.32/278.57.27.33 to 8.57.27.628.57.27.6330
2198.57.27.64/278.57.27.65 to 8.57.27.948.57.27.9530
2208.57.27.96/278.57.27.97 to 8.57.27.1268.57.27.12730
2218.57.27.128/278.57.27.129 to 8.57.27.1588.57.27.15930
2228.57.27.160/278.57.27.161 to 8.57.27.1908.57.27.19130
2238.57.27.192/278.57.27.193 to 8.57.27.2228.57.27.22330
2248.57.27.224/278.57.27.225 to 8.57.27.2548.57.27.25530
2258.57.28.0/278.57.28.1 to 8.57.28.308.57.28.3130
2268.57.28.32/278.57.28.33 to 8.57.28.628.57.28.6330
2278.57.28.64/278.57.28.65 to 8.57.28.948.57.28.9530
2288.57.28.96/278.57.28.97 to 8.57.28.1268.57.28.12730
2298.57.28.128/278.57.28.129 to 8.57.28.1588.57.28.15930
2308.57.28.160/278.57.28.161 to 8.57.28.1908.57.28.19130
2318.57.28.192/278.57.28.193 to 8.57.28.2228.57.28.22330
2328.57.28.224/278.57.28.225 to 8.57.28.2548.57.28.25530
2338.57.29.0/278.57.29.1 to 8.57.29.308.57.29.3130
2348.57.29.32/278.57.29.33 to 8.57.29.628.57.29.6330
2358.57.29.64/278.57.29.65 to 8.57.29.948.57.29.9530
2368.57.29.96/278.57.29.97 to 8.57.29.1268.57.29.12730
2378.57.29.128/278.57.29.129 to 8.57.29.1588.57.29.15930
2388.57.29.160/278.57.29.161 to 8.57.29.1908.57.29.19130
2398.57.29.192/278.57.29.193 to 8.57.29.2228.57.29.22330
2408.57.29.224/278.57.29.225 to 8.57.29.2548.57.29.25530
2418.57.30.0/278.57.30.1 to 8.57.30.308.57.30.3130
2428.57.30.32/278.57.30.33 to 8.57.30.628.57.30.6330
2438.57.30.64/278.57.30.65 to 8.57.30.948.57.30.9530
2448.57.30.96/278.57.30.97 to 8.57.30.1268.57.30.12730
2458.57.30.128/278.57.30.129 to 8.57.30.1588.57.30.15930
2468.57.30.160/278.57.30.161 to 8.57.30.1908.57.30.19130
2478.57.30.192/278.57.30.193 to 8.57.30.2228.57.30.22330
2488.57.30.224/278.57.30.225 to 8.57.30.2548.57.30.25530
2498.57.31.0/278.57.31.1 to 8.57.31.308.57.31.3130
2508.57.31.32/278.57.31.33 to 8.57.31.628.57.31.6330
2518.57.31.64/278.57.31.65 to 8.57.31.948.57.31.9530
2528.57.31.96/278.57.31.97 to 8.57.31.1268.57.31.12730
2538.57.31.128/278.57.31.129 to 8.57.31.1588.57.31.15930
2548.57.31.160/278.57.31.161 to 8.57.31.1908.57.31.19130
2558.57.31.192/278.57.31.193 to 8.57.31.2228.57.31.22330
2568.57.31.224/278.57.31.225 to 8.57.31.2548.57.31.25530

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.