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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.

Network65.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
65.0.0.0
Broadcast address
65.127.255.255
First usable
65.0.0.1
Last usable
65.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 41000000 · Integer 1090519040 to 1098907647
Reverse DNS zones
0.65.in-addr.arpa
1.65.in-addr.arpa
2.65.in-addr.arpa
3.65.in-addr.arpa
4.65.in-addr.arpa
5.65.in-addr.arpa
6.65.in-addr.arpa
7.65.in-addr.arpa
8.65.in-addr.arpa
9.65.in-addr.arpa
10.65.in-addr.arpa
11.65.in-addr.arpa
12.65.in-addr.arpa
13.65.in-addr.arpa
14.65.in-addr.arpa
15.65.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000001.00000000.00000000.0000000065.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01000001.00000000.00000000.0000000065.0.0.0
Broadcast01000001.01111111.11111111.1111111165.127.255.255
Split into smaller subnets/20
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

65.0.0.0/9 makes 2,048 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
165.0.0.0/2065.0.0.1 to 65.0.15.25465.0.15.2554,094
265.0.16.0/2065.0.16.1 to 65.0.31.25465.0.31.2554,094
365.0.32.0/2065.0.32.1 to 65.0.47.25465.0.47.2554,094
465.0.48.0/2065.0.48.1 to 65.0.63.25465.0.63.2554,094
565.0.64.0/2065.0.64.1 to 65.0.79.25465.0.79.2554,094
665.0.80.0/2065.0.80.1 to 65.0.95.25465.0.95.2554,094
765.0.96.0/2065.0.96.1 to 65.0.111.25465.0.111.2554,094
865.0.112.0/2065.0.112.1 to 65.0.127.25465.0.127.2554,094
965.0.128.0/2065.0.128.1 to 65.0.143.25465.0.143.2554,094
1065.0.144.0/2065.0.144.1 to 65.0.159.25465.0.159.2554,094
1165.0.160.0/2065.0.160.1 to 65.0.175.25465.0.175.2554,094
1265.0.176.0/2065.0.176.1 to 65.0.191.25465.0.191.2554,094
1365.0.192.0/2065.0.192.1 to 65.0.207.25465.0.207.2554,094
1465.0.208.0/2065.0.208.1 to 65.0.223.25465.0.223.2554,094
1565.0.224.0/2065.0.224.1 to 65.0.239.25465.0.239.2554,094
1665.0.240.0/2065.0.240.1 to 65.0.255.25465.0.255.2554,094
1765.1.0.0/2065.1.0.1 to 65.1.15.25465.1.15.2554,094
1865.1.16.0/2065.1.16.1 to 65.1.31.25465.1.31.2554,094
1965.1.32.0/2065.1.32.1 to 65.1.47.25465.1.47.2554,094
2065.1.48.0/2065.1.48.1 to 65.1.63.25465.1.63.2554,094
2165.1.64.0/2065.1.64.1 to 65.1.79.25465.1.79.2554,094
2265.1.80.0/2065.1.80.1 to 65.1.95.25465.1.95.2554,094
2365.1.96.0/2065.1.96.1 to 65.1.111.25465.1.111.2554,094
2465.1.112.0/2065.1.112.1 to 65.1.127.25465.1.127.2554,094
2565.1.128.0/2065.1.128.1 to 65.1.143.25465.1.143.2554,094
2665.1.144.0/2065.1.144.1 to 65.1.159.25465.1.159.2554,094
2765.1.160.0/2065.1.160.1 to 65.1.175.25465.1.175.2554,094
2865.1.176.0/2065.1.176.1 to 65.1.191.25465.1.191.2554,094
2965.1.192.0/2065.1.192.1 to 65.1.207.25465.1.207.2554,094
3065.1.208.0/2065.1.208.1 to 65.1.223.25465.1.223.2554,094
3165.1.224.0/2065.1.224.1 to 65.1.239.25465.1.239.2554,094
3265.1.240.0/2065.1.240.1 to 65.1.255.25465.1.255.2554,094
3365.2.0.0/2065.2.0.1 to 65.2.15.25465.2.15.2554,094
3465.2.16.0/2065.2.16.1 to 65.2.31.25465.2.31.2554,094
3565.2.32.0/2065.2.32.1 to 65.2.47.25465.2.47.2554,094
3665.2.48.0/2065.2.48.1 to 65.2.63.25465.2.63.2554,094
3765.2.64.0/2065.2.64.1 to 65.2.79.25465.2.79.2554,094
3865.2.80.0/2065.2.80.1 to 65.2.95.25465.2.95.2554,094
3965.2.96.0/2065.2.96.1 to 65.2.111.25465.2.111.2554,094
4065.2.112.0/2065.2.112.1 to 65.2.127.25465.2.127.2554,094
4165.2.128.0/2065.2.128.1 to 65.2.143.25465.2.143.2554,094
4265.2.144.0/2065.2.144.1 to 65.2.159.25465.2.159.2554,094
4365.2.160.0/2065.2.160.1 to 65.2.175.25465.2.175.2554,094
4465.2.176.0/2065.2.176.1 to 65.2.191.25465.2.191.2554,094
4565.2.192.0/2065.2.192.1 to 65.2.207.25465.2.207.2554,094
4665.2.208.0/2065.2.208.1 to 65.2.223.25465.2.223.2554,094
4765.2.224.0/2065.2.224.1 to 65.2.239.25465.2.239.2554,094
4865.2.240.0/2065.2.240.1 to 65.2.255.25465.2.255.2554,094
4965.3.0.0/2065.3.0.1 to 65.3.15.25465.3.15.2554,094
5065.3.16.0/2065.3.16.1 to 65.3.31.25465.3.31.2554,094
5165.3.32.0/2065.3.32.1 to 65.3.47.25465.3.47.2554,094
5265.3.48.0/2065.3.48.1 to 65.3.63.25465.3.63.2554,094
5365.3.64.0/2065.3.64.1 to 65.3.79.25465.3.79.2554,094
5465.3.80.0/2065.3.80.1 to 65.3.95.25465.3.95.2554,094
5565.3.96.0/2065.3.96.1 to 65.3.111.25465.3.111.2554,094
5665.3.112.0/2065.3.112.1 to 65.3.127.25465.3.127.2554,094
5765.3.128.0/2065.3.128.1 to 65.3.143.25465.3.143.2554,094
5865.3.144.0/2065.3.144.1 to 65.3.159.25465.3.159.2554,094
5965.3.160.0/2065.3.160.1 to 65.3.175.25465.3.175.2554,094
6065.3.176.0/2065.3.176.1 to 65.3.191.25465.3.191.2554,094
6165.3.192.0/2065.3.192.1 to 65.3.207.25465.3.207.2554,094
6265.3.208.0/2065.3.208.1 to 65.3.223.25465.3.223.2554,094
6365.3.224.0/2065.3.224.1 to 65.3.239.25465.3.239.2554,094
6465.3.240.0/2065.3.240.1 to 65.3.255.25465.3.255.2554,094
6565.4.0.0/2065.4.0.1 to 65.4.15.25465.4.15.2554,094
6665.4.16.0/2065.4.16.1 to 65.4.31.25465.4.31.2554,094
6765.4.32.0/2065.4.32.1 to 65.4.47.25465.4.47.2554,094
6865.4.48.0/2065.4.48.1 to 65.4.63.25465.4.63.2554,094
6965.4.64.0/2065.4.64.1 to 65.4.79.25465.4.79.2554,094
7065.4.80.0/2065.4.80.1 to 65.4.95.25465.4.95.2554,094
7165.4.96.0/2065.4.96.1 to 65.4.111.25465.4.111.2554,094
7265.4.112.0/2065.4.112.1 to 65.4.127.25465.4.127.2554,094
7365.4.128.0/2065.4.128.1 to 65.4.143.25465.4.143.2554,094
7465.4.144.0/2065.4.144.1 to 65.4.159.25465.4.159.2554,094
7565.4.160.0/2065.4.160.1 to 65.4.175.25465.4.175.2554,094
7665.4.176.0/2065.4.176.1 to 65.4.191.25465.4.191.2554,094
7765.4.192.0/2065.4.192.1 to 65.4.207.25465.4.207.2554,094
7865.4.208.0/2065.4.208.1 to 65.4.223.25465.4.223.2554,094
7965.4.224.0/2065.4.224.1 to 65.4.239.25465.4.239.2554,094
8065.4.240.0/2065.4.240.1 to 65.4.255.25465.4.255.2554,094
8165.5.0.0/2065.5.0.1 to 65.5.15.25465.5.15.2554,094
8265.5.16.0/2065.5.16.1 to 65.5.31.25465.5.31.2554,094
8365.5.32.0/2065.5.32.1 to 65.5.47.25465.5.47.2554,094
8465.5.48.0/2065.5.48.1 to 65.5.63.25465.5.63.2554,094
8565.5.64.0/2065.5.64.1 to 65.5.79.25465.5.79.2554,094
8665.5.80.0/2065.5.80.1 to 65.5.95.25465.5.95.2554,094
8765.5.96.0/2065.5.96.1 to 65.5.111.25465.5.111.2554,094
8865.5.112.0/2065.5.112.1 to 65.5.127.25465.5.127.2554,094
8965.5.128.0/2065.5.128.1 to 65.5.143.25465.5.143.2554,094
9065.5.144.0/2065.5.144.1 to 65.5.159.25465.5.159.2554,094
9165.5.160.0/2065.5.160.1 to 65.5.175.25465.5.175.2554,094
9265.5.176.0/2065.5.176.1 to 65.5.191.25465.5.191.2554,094
9365.5.192.0/2065.5.192.1 to 65.5.207.25465.5.207.2554,094
9465.5.208.0/2065.5.208.1 to 65.5.223.25465.5.223.2554,094
9565.5.224.0/2065.5.224.1 to 65.5.239.25465.5.239.2554,094
9665.5.240.0/2065.5.240.1 to 65.5.255.25465.5.255.2554,094
9765.6.0.0/2065.6.0.1 to 65.6.15.25465.6.15.2554,094
9865.6.16.0/2065.6.16.1 to 65.6.31.25465.6.31.2554,094
9965.6.32.0/2065.6.32.1 to 65.6.47.25465.6.47.2554,094
10065.6.48.0/2065.6.48.1 to 65.6.63.25465.6.63.2554,094
10165.6.64.0/2065.6.64.1 to 65.6.79.25465.6.79.2554,094
10265.6.80.0/2065.6.80.1 to 65.6.95.25465.6.95.2554,094
10365.6.96.0/2065.6.96.1 to 65.6.111.25465.6.111.2554,094
10465.6.112.0/2065.6.112.1 to 65.6.127.25465.6.127.2554,094
10565.6.128.0/2065.6.128.1 to 65.6.143.25465.6.143.2554,094
10665.6.144.0/2065.6.144.1 to 65.6.159.25465.6.159.2554,094
10765.6.160.0/2065.6.160.1 to 65.6.175.25465.6.175.2554,094
10865.6.176.0/2065.6.176.1 to 65.6.191.25465.6.191.2554,094
10965.6.192.0/2065.6.192.1 to 65.6.207.25465.6.207.2554,094
11065.6.208.0/2065.6.208.1 to 65.6.223.25465.6.223.2554,094
11165.6.224.0/2065.6.224.1 to 65.6.239.25465.6.239.2554,094
11265.6.240.0/2065.6.240.1 to 65.6.255.25465.6.255.2554,094
11365.7.0.0/2065.7.0.1 to 65.7.15.25465.7.15.2554,094
11465.7.16.0/2065.7.16.1 to 65.7.31.25465.7.31.2554,094
11565.7.32.0/2065.7.32.1 to 65.7.47.25465.7.47.2554,094
11665.7.48.0/2065.7.48.1 to 65.7.63.25465.7.63.2554,094
11765.7.64.0/2065.7.64.1 to 65.7.79.25465.7.79.2554,094
11865.7.80.0/2065.7.80.1 to 65.7.95.25465.7.95.2554,094
11965.7.96.0/2065.7.96.1 to 65.7.111.25465.7.111.2554,094
12065.7.112.0/2065.7.112.1 to 65.7.127.25465.7.127.2554,094
12165.7.128.0/2065.7.128.1 to 65.7.143.25465.7.143.2554,094
12265.7.144.0/2065.7.144.1 to 65.7.159.25465.7.159.2554,094
12365.7.160.0/2065.7.160.1 to 65.7.175.25465.7.175.2554,094
12465.7.176.0/2065.7.176.1 to 65.7.191.25465.7.191.2554,094
12565.7.192.0/2065.7.192.1 to 65.7.207.25465.7.207.2554,094
12665.7.208.0/2065.7.208.1 to 65.7.223.25465.7.223.2554,094
12765.7.224.0/2065.7.224.1 to 65.7.239.25465.7.239.2554,094
12865.7.240.0/2065.7.240.1 to 65.7.255.25465.7.255.2554,094
12965.8.0.0/2065.8.0.1 to 65.8.15.25465.8.15.2554,094
13065.8.16.0/2065.8.16.1 to 65.8.31.25465.8.31.2554,094
13165.8.32.0/2065.8.32.1 to 65.8.47.25465.8.47.2554,094
13265.8.48.0/2065.8.48.1 to 65.8.63.25465.8.63.2554,094
13365.8.64.0/2065.8.64.1 to 65.8.79.25465.8.79.2554,094
13465.8.80.0/2065.8.80.1 to 65.8.95.25465.8.95.2554,094
13565.8.96.0/2065.8.96.1 to 65.8.111.25465.8.111.2554,094
13665.8.112.0/2065.8.112.1 to 65.8.127.25465.8.127.2554,094
13765.8.128.0/2065.8.128.1 to 65.8.143.25465.8.143.2554,094
13865.8.144.0/2065.8.144.1 to 65.8.159.25465.8.159.2554,094
13965.8.160.0/2065.8.160.1 to 65.8.175.25465.8.175.2554,094
14065.8.176.0/2065.8.176.1 to 65.8.191.25465.8.191.2554,094
14165.8.192.0/2065.8.192.1 to 65.8.207.25465.8.207.2554,094
14265.8.208.0/2065.8.208.1 to 65.8.223.25465.8.223.2554,094
14365.8.224.0/2065.8.224.1 to 65.8.239.25465.8.239.2554,094
14465.8.240.0/2065.8.240.1 to 65.8.255.25465.8.255.2554,094
14565.9.0.0/2065.9.0.1 to 65.9.15.25465.9.15.2554,094
14665.9.16.0/2065.9.16.1 to 65.9.31.25465.9.31.2554,094
14765.9.32.0/2065.9.32.1 to 65.9.47.25465.9.47.2554,094
14865.9.48.0/2065.9.48.1 to 65.9.63.25465.9.63.2554,094
14965.9.64.0/2065.9.64.1 to 65.9.79.25465.9.79.2554,094
15065.9.80.0/2065.9.80.1 to 65.9.95.25465.9.95.2554,094
15165.9.96.0/2065.9.96.1 to 65.9.111.25465.9.111.2554,094
15265.9.112.0/2065.9.112.1 to 65.9.127.25465.9.127.2554,094
15365.9.128.0/2065.9.128.1 to 65.9.143.25465.9.143.2554,094
15465.9.144.0/2065.9.144.1 to 65.9.159.25465.9.159.2554,094
15565.9.160.0/2065.9.160.1 to 65.9.175.25465.9.175.2554,094
15665.9.176.0/2065.9.176.1 to 65.9.191.25465.9.191.2554,094
15765.9.192.0/2065.9.192.1 to 65.9.207.25465.9.207.2554,094
15865.9.208.0/2065.9.208.1 to 65.9.223.25465.9.223.2554,094
15965.9.224.0/2065.9.224.1 to 65.9.239.25465.9.239.2554,094
16065.9.240.0/2065.9.240.1 to 65.9.255.25465.9.255.2554,094
16165.10.0.0/2065.10.0.1 to 65.10.15.25465.10.15.2554,094
16265.10.16.0/2065.10.16.1 to 65.10.31.25465.10.31.2554,094
16365.10.32.0/2065.10.32.1 to 65.10.47.25465.10.47.2554,094
16465.10.48.0/2065.10.48.1 to 65.10.63.25465.10.63.2554,094
16565.10.64.0/2065.10.64.1 to 65.10.79.25465.10.79.2554,094
16665.10.80.0/2065.10.80.1 to 65.10.95.25465.10.95.2554,094
16765.10.96.0/2065.10.96.1 to 65.10.111.25465.10.111.2554,094
16865.10.112.0/2065.10.112.1 to 65.10.127.25465.10.127.2554,094
16965.10.128.0/2065.10.128.1 to 65.10.143.25465.10.143.2554,094
17065.10.144.0/2065.10.144.1 to 65.10.159.25465.10.159.2554,094
17165.10.160.0/2065.10.160.1 to 65.10.175.25465.10.175.2554,094
17265.10.176.0/2065.10.176.1 to 65.10.191.25465.10.191.2554,094
17365.10.192.0/2065.10.192.1 to 65.10.207.25465.10.207.2554,094
17465.10.208.0/2065.10.208.1 to 65.10.223.25465.10.223.2554,094
17565.10.224.0/2065.10.224.1 to 65.10.239.25465.10.239.2554,094
17665.10.240.0/2065.10.240.1 to 65.10.255.25465.10.255.2554,094
17765.11.0.0/2065.11.0.1 to 65.11.15.25465.11.15.2554,094
17865.11.16.0/2065.11.16.1 to 65.11.31.25465.11.31.2554,094
17965.11.32.0/2065.11.32.1 to 65.11.47.25465.11.47.2554,094
18065.11.48.0/2065.11.48.1 to 65.11.63.25465.11.63.2554,094
18165.11.64.0/2065.11.64.1 to 65.11.79.25465.11.79.2554,094
18265.11.80.0/2065.11.80.1 to 65.11.95.25465.11.95.2554,094
18365.11.96.0/2065.11.96.1 to 65.11.111.25465.11.111.2554,094
18465.11.112.0/2065.11.112.1 to 65.11.127.25465.11.127.2554,094
18565.11.128.0/2065.11.128.1 to 65.11.143.25465.11.143.2554,094
18665.11.144.0/2065.11.144.1 to 65.11.159.25465.11.159.2554,094
18765.11.160.0/2065.11.160.1 to 65.11.175.25465.11.175.2554,094
18865.11.176.0/2065.11.176.1 to 65.11.191.25465.11.191.2554,094
18965.11.192.0/2065.11.192.1 to 65.11.207.25465.11.207.2554,094
19065.11.208.0/2065.11.208.1 to 65.11.223.25465.11.223.2554,094
19165.11.224.0/2065.11.224.1 to 65.11.239.25465.11.239.2554,094
19265.11.240.0/2065.11.240.1 to 65.11.255.25465.11.255.2554,094
19365.12.0.0/2065.12.0.1 to 65.12.15.25465.12.15.2554,094
19465.12.16.0/2065.12.16.1 to 65.12.31.25465.12.31.2554,094
19565.12.32.0/2065.12.32.1 to 65.12.47.25465.12.47.2554,094
19665.12.48.0/2065.12.48.1 to 65.12.63.25465.12.63.2554,094
19765.12.64.0/2065.12.64.1 to 65.12.79.25465.12.79.2554,094
19865.12.80.0/2065.12.80.1 to 65.12.95.25465.12.95.2554,094
19965.12.96.0/2065.12.96.1 to 65.12.111.25465.12.111.2554,094
20065.12.112.0/2065.12.112.1 to 65.12.127.25465.12.127.2554,094
20165.12.128.0/2065.12.128.1 to 65.12.143.25465.12.143.2554,094
20265.12.144.0/2065.12.144.1 to 65.12.159.25465.12.159.2554,094
20365.12.160.0/2065.12.160.1 to 65.12.175.25465.12.175.2554,094
20465.12.176.0/2065.12.176.1 to 65.12.191.25465.12.191.2554,094
20565.12.192.0/2065.12.192.1 to 65.12.207.25465.12.207.2554,094
20665.12.208.0/2065.12.208.1 to 65.12.223.25465.12.223.2554,094
20765.12.224.0/2065.12.224.1 to 65.12.239.25465.12.239.2554,094
20865.12.240.0/2065.12.240.1 to 65.12.255.25465.12.255.2554,094
20965.13.0.0/2065.13.0.1 to 65.13.15.25465.13.15.2554,094
21065.13.16.0/2065.13.16.1 to 65.13.31.25465.13.31.2554,094
21165.13.32.0/2065.13.32.1 to 65.13.47.25465.13.47.2554,094
21265.13.48.0/2065.13.48.1 to 65.13.63.25465.13.63.2554,094
21365.13.64.0/2065.13.64.1 to 65.13.79.25465.13.79.2554,094
21465.13.80.0/2065.13.80.1 to 65.13.95.25465.13.95.2554,094
21565.13.96.0/2065.13.96.1 to 65.13.111.25465.13.111.2554,094
21665.13.112.0/2065.13.112.1 to 65.13.127.25465.13.127.2554,094
21765.13.128.0/2065.13.128.1 to 65.13.143.25465.13.143.2554,094
21865.13.144.0/2065.13.144.1 to 65.13.159.25465.13.159.2554,094
21965.13.160.0/2065.13.160.1 to 65.13.175.25465.13.175.2554,094
22065.13.176.0/2065.13.176.1 to 65.13.191.25465.13.191.2554,094
22165.13.192.0/2065.13.192.1 to 65.13.207.25465.13.207.2554,094
22265.13.208.0/2065.13.208.1 to 65.13.223.25465.13.223.2554,094
22365.13.224.0/2065.13.224.1 to 65.13.239.25465.13.239.2554,094
22465.13.240.0/2065.13.240.1 to 65.13.255.25465.13.255.2554,094
22565.14.0.0/2065.14.0.1 to 65.14.15.25465.14.15.2554,094
22665.14.16.0/2065.14.16.1 to 65.14.31.25465.14.31.2554,094
22765.14.32.0/2065.14.32.1 to 65.14.47.25465.14.47.2554,094
22865.14.48.0/2065.14.48.1 to 65.14.63.25465.14.63.2554,094
22965.14.64.0/2065.14.64.1 to 65.14.79.25465.14.79.2554,094
23065.14.80.0/2065.14.80.1 to 65.14.95.25465.14.95.2554,094
23165.14.96.0/2065.14.96.1 to 65.14.111.25465.14.111.2554,094
23265.14.112.0/2065.14.112.1 to 65.14.127.25465.14.127.2554,094
23365.14.128.0/2065.14.128.1 to 65.14.143.25465.14.143.2554,094
23465.14.144.0/2065.14.144.1 to 65.14.159.25465.14.159.2554,094
23565.14.160.0/2065.14.160.1 to 65.14.175.25465.14.175.2554,094
23665.14.176.0/2065.14.176.1 to 65.14.191.25465.14.191.2554,094
23765.14.192.0/2065.14.192.1 to 65.14.207.25465.14.207.2554,094
23865.14.208.0/2065.14.208.1 to 65.14.223.25465.14.223.2554,094
23965.14.224.0/2065.14.224.1 to 65.14.239.25465.14.239.2554,094
24065.14.240.0/2065.14.240.1 to 65.14.255.25465.14.255.2554,094
24165.15.0.0/2065.15.0.1 to 65.15.15.25465.15.15.2554,094
24265.15.16.0/2065.15.16.1 to 65.15.31.25465.15.31.2554,094
24365.15.32.0/2065.15.32.1 to 65.15.47.25465.15.47.2554,094
24465.15.48.0/2065.15.48.1 to 65.15.63.25465.15.63.2554,094
24565.15.64.0/2065.15.64.1 to 65.15.79.25465.15.79.2554,094
24665.15.80.0/2065.15.80.1 to 65.15.95.25465.15.95.2554,094
24765.15.96.0/2065.15.96.1 to 65.15.111.25465.15.111.2554,094
24865.15.112.0/2065.15.112.1 to 65.15.127.25465.15.127.2554,094
24965.15.128.0/2065.15.128.1 to 65.15.143.25465.15.143.2554,094
25065.15.144.0/2065.15.144.1 to 65.15.159.25465.15.159.2554,094
25165.15.160.0/2065.15.160.1 to 65.15.175.25465.15.175.2554,094
25265.15.176.0/2065.15.176.1 to 65.15.191.25465.15.191.2554,094
25365.15.192.0/2065.15.192.1 to 65.15.207.25465.15.207.2554,094
25465.15.208.0/2065.15.208.1 to 65.15.223.25465.15.223.2554,094
25565.15.224.0/2065.15.224.1 to 65.15.239.25465.15.239.2554,094
25665.15.240.0/2065.15.240.1 to 65.15.255.25465.15.255.2554,094

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.