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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.

Network65.185.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
65.185.0.0
Broadcast address
65.185.127.255
First usable
65.185.0.1
Last usable
65.185.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
A (default /8)
As numbers
Hex 41B90000 · Integer 1102643200 to 1102675967
Reverse DNS zones
0.185.65.in-addr.arpa
1.185.65.in-addr.arpa
2.185.65.in-addr.arpa
3.185.65.in-addr.arpa
4.185.65.in-addr.arpa
5.185.65.in-addr.arpa
6.185.65.in-addr.arpa
7.185.65.in-addr.arpa
8.185.65.in-addr.arpa
9.185.65.in-addr.arpa
10.185.65.in-addr.arpa
11.185.65.in-addr.arpa
12.185.65.in-addr.arpa
13.185.65.in-addr.arpa
14.185.65.in-addr.arpa
15.185.65.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000001.10111001.00000000.0000000065.185.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network01000001.10111001.00000000.0000000065.185.0.0
Broadcast01000001.10111001.01111111.1111111165.185.127.255
Split into smaller subnets/26
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

65.185.0.0/17 makes 512 subnets of /26; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
165.185.0.0/2665.185.0.1 to 65.185.0.6265.185.0.6362
265.185.0.64/2665.185.0.65 to 65.185.0.12665.185.0.12762
365.185.0.128/2665.185.0.129 to 65.185.0.19065.185.0.19162
465.185.0.192/2665.185.0.193 to 65.185.0.25465.185.0.25562
565.185.1.0/2665.185.1.1 to 65.185.1.6265.185.1.6362
665.185.1.64/2665.185.1.65 to 65.185.1.12665.185.1.12762
765.185.1.128/2665.185.1.129 to 65.185.1.19065.185.1.19162
865.185.1.192/2665.185.1.193 to 65.185.1.25465.185.1.25562
965.185.2.0/2665.185.2.1 to 65.185.2.6265.185.2.6362
1065.185.2.64/2665.185.2.65 to 65.185.2.12665.185.2.12762
1165.185.2.128/2665.185.2.129 to 65.185.2.19065.185.2.19162
1265.185.2.192/2665.185.2.193 to 65.185.2.25465.185.2.25562
1365.185.3.0/2665.185.3.1 to 65.185.3.6265.185.3.6362
1465.185.3.64/2665.185.3.65 to 65.185.3.12665.185.3.12762
1565.185.3.128/2665.185.3.129 to 65.185.3.19065.185.3.19162
1665.185.3.192/2665.185.3.193 to 65.185.3.25465.185.3.25562
1765.185.4.0/2665.185.4.1 to 65.185.4.6265.185.4.6362
1865.185.4.64/2665.185.4.65 to 65.185.4.12665.185.4.12762
1965.185.4.128/2665.185.4.129 to 65.185.4.19065.185.4.19162
2065.185.4.192/2665.185.4.193 to 65.185.4.25465.185.4.25562
2165.185.5.0/2665.185.5.1 to 65.185.5.6265.185.5.6362
2265.185.5.64/2665.185.5.65 to 65.185.5.12665.185.5.12762
2365.185.5.128/2665.185.5.129 to 65.185.5.19065.185.5.19162
2465.185.5.192/2665.185.5.193 to 65.185.5.25465.185.5.25562
2565.185.6.0/2665.185.6.1 to 65.185.6.6265.185.6.6362
2665.185.6.64/2665.185.6.65 to 65.185.6.12665.185.6.12762
2765.185.6.128/2665.185.6.129 to 65.185.6.19065.185.6.19162
2865.185.6.192/2665.185.6.193 to 65.185.6.25465.185.6.25562
2965.185.7.0/2665.185.7.1 to 65.185.7.6265.185.7.6362
3065.185.7.64/2665.185.7.65 to 65.185.7.12665.185.7.12762
3165.185.7.128/2665.185.7.129 to 65.185.7.19065.185.7.19162
3265.185.7.192/2665.185.7.193 to 65.185.7.25465.185.7.25562
3365.185.8.0/2665.185.8.1 to 65.185.8.6265.185.8.6362
3465.185.8.64/2665.185.8.65 to 65.185.8.12665.185.8.12762
3565.185.8.128/2665.185.8.129 to 65.185.8.19065.185.8.19162
3665.185.8.192/2665.185.8.193 to 65.185.8.25465.185.8.25562
3765.185.9.0/2665.185.9.1 to 65.185.9.6265.185.9.6362
3865.185.9.64/2665.185.9.65 to 65.185.9.12665.185.9.12762
3965.185.9.128/2665.185.9.129 to 65.185.9.19065.185.9.19162
4065.185.9.192/2665.185.9.193 to 65.185.9.25465.185.9.25562
4165.185.10.0/2665.185.10.1 to 65.185.10.6265.185.10.6362
4265.185.10.64/2665.185.10.65 to 65.185.10.12665.185.10.12762
4365.185.10.128/2665.185.10.129 to 65.185.10.19065.185.10.19162
4465.185.10.192/2665.185.10.193 to 65.185.10.25465.185.10.25562
4565.185.11.0/2665.185.11.1 to 65.185.11.6265.185.11.6362
4665.185.11.64/2665.185.11.65 to 65.185.11.12665.185.11.12762
4765.185.11.128/2665.185.11.129 to 65.185.11.19065.185.11.19162
4865.185.11.192/2665.185.11.193 to 65.185.11.25465.185.11.25562
4965.185.12.0/2665.185.12.1 to 65.185.12.6265.185.12.6362
5065.185.12.64/2665.185.12.65 to 65.185.12.12665.185.12.12762
5165.185.12.128/2665.185.12.129 to 65.185.12.19065.185.12.19162
5265.185.12.192/2665.185.12.193 to 65.185.12.25465.185.12.25562
5365.185.13.0/2665.185.13.1 to 65.185.13.6265.185.13.6362
5465.185.13.64/2665.185.13.65 to 65.185.13.12665.185.13.12762
5565.185.13.128/2665.185.13.129 to 65.185.13.19065.185.13.19162
5665.185.13.192/2665.185.13.193 to 65.185.13.25465.185.13.25562
5765.185.14.0/2665.185.14.1 to 65.185.14.6265.185.14.6362
5865.185.14.64/2665.185.14.65 to 65.185.14.12665.185.14.12762
5965.185.14.128/2665.185.14.129 to 65.185.14.19065.185.14.19162
6065.185.14.192/2665.185.14.193 to 65.185.14.25465.185.14.25562
6165.185.15.0/2665.185.15.1 to 65.185.15.6265.185.15.6362
6265.185.15.64/2665.185.15.65 to 65.185.15.12665.185.15.12762
6365.185.15.128/2665.185.15.129 to 65.185.15.19065.185.15.19162
6465.185.15.192/2665.185.15.193 to 65.185.15.25465.185.15.25562
6565.185.16.0/2665.185.16.1 to 65.185.16.6265.185.16.6362
6665.185.16.64/2665.185.16.65 to 65.185.16.12665.185.16.12762
6765.185.16.128/2665.185.16.129 to 65.185.16.19065.185.16.19162
6865.185.16.192/2665.185.16.193 to 65.185.16.25465.185.16.25562
6965.185.17.0/2665.185.17.1 to 65.185.17.6265.185.17.6362
7065.185.17.64/2665.185.17.65 to 65.185.17.12665.185.17.12762
7165.185.17.128/2665.185.17.129 to 65.185.17.19065.185.17.19162
7265.185.17.192/2665.185.17.193 to 65.185.17.25465.185.17.25562
7365.185.18.0/2665.185.18.1 to 65.185.18.6265.185.18.6362
7465.185.18.64/2665.185.18.65 to 65.185.18.12665.185.18.12762
7565.185.18.128/2665.185.18.129 to 65.185.18.19065.185.18.19162
7665.185.18.192/2665.185.18.193 to 65.185.18.25465.185.18.25562
7765.185.19.0/2665.185.19.1 to 65.185.19.6265.185.19.6362
7865.185.19.64/2665.185.19.65 to 65.185.19.12665.185.19.12762
7965.185.19.128/2665.185.19.129 to 65.185.19.19065.185.19.19162
8065.185.19.192/2665.185.19.193 to 65.185.19.25465.185.19.25562
8165.185.20.0/2665.185.20.1 to 65.185.20.6265.185.20.6362
8265.185.20.64/2665.185.20.65 to 65.185.20.12665.185.20.12762
8365.185.20.128/2665.185.20.129 to 65.185.20.19065.185.20.19162
8465.185.20.192/2665.185.20.193 to 65.185.20.25465.185.20.25562
8565.185.21.0/2665.185.21.1 to 65.185.21.6265.185.21.6362
8665.185.21.64/2665.185.21.65 to 65.185.21.12665.185.21.12762
8765.185.21.128/2665.185.21.129 to 65.185.21.19065.185.21.19162
8865.185.21.192/2665.185.21.193 to 65.185.21.25465.185.21.25562
8965.185.22.0/2665.185.22.1 to 65.185.22.6265.185.22.6362
9065.185.22.64/2665.185.22.65 to 65.185.22.12665.185.22.12762
9165.185.22.128/2665.185.22.129 to 65.185.22.19065.185.22.19162
9265.185.22.192/2665.185.22.193 to 65.185.22.25465.185.22.25562
9365.185.23.0/2665.185.23.1 to 65.185.23.6265.185.23.6362
9465.185.23.64/2665.185.23.65 to 65.185.23.12665.185.23.12762
9565.185.23.128/2665.185.23.129 to 65.185.23.19065.185.23.19162
9665.185.23.192/2665.185.23.193 to 65.185.23.25465.185.23.25562
9765.185.24.0/2665.185.24.1 to 65.185.24.6265.185.24.6362
9865.185.24.64/2665.185.24.65 to 65.185.24.12665.185.24.12762
9965.185.24.128/2665.185.24.129 to 65.185.24.19065.185.24.19162
10065.185.24.192/2665.185.24.193 to 65.185.24.25465.185.24.25562
10165.185.25.0/2665.185.25.1 to 65.185.25.6265.185.25.6362
10265.185.25.64/2665.185.25.65 to 65.185.25.12665.185.25.12762
10365.185.25.128/2665.185.25.129 to 65.185.25.19065.185.25.19162
10465.185.25.192/2665.185.25.193 to 65.185.25.25465.185.25.25562
10565.185.26.0/2665.185.26.1 to 65.185.26.6265.185.26.6362
10665.185.26.64/2665.185.26.65 to 65.185.26.12665.185.26.12762
10765.185.26.128/2665.185.26.129 to 65.185.26.19065.185.26.19162
10865.185.26.192/2665.185.26.193 to 65.185.26.25465.185.26.25562
10965.185.27.0/2665.185.27.1 to 65.185.27.6265.185.27.6362
11065.185.27.64/2665.185.27.65 to 65.185.27.12665.185.27.12762
11165.185.27.128/2665.185.27.129 to 65.185.27.19065.185.27.19162
11265.185.27.192/2665.185.27.193 to 65.185.27.25465.185.27.25562
11365.185.28.0/2665.185.28.1 to 65.185.28.6265.185.28.6362
11465.185.28.64/2665.185.28.65 to 65.185.28.12665.185.28.12762
11565.185.28.128/2665.185.28.129 to 65.185.28.19065.185.28.19162
11665.185.28.192/2665.185.28.193 to 65.185.28.25465.185.28.25562
11765.185.29.0/2665.185.29.1 to 65.185.29.6265.185.29.6362
11865.185.29.64/2665.185.29.65 to 65.185.29.12665.185.29.12762
11965.185.29.128/2665.185.29.129 to 65.185.29.19065.185.29.19162
12065.185.29.192/2665.185.29.193 to 65.185.29.25465.185.29.25562
12165.185.30.0/2665.185.30.1 to 65.185.30.6265.185.30.6362
12265.185.30.64/2665.185.30.65 to 65.185.30.12665.185.30.12762
12365.185.30.128/2665.185.30.129 to 65.185.30.19065.185.30.19162
12465.185.30.192/2665.185.30.193 to 65.185.30.25465.185.30.25562
12565.185.31.0/2665.185.31.1 to 65.185.31.6265.185.31.6362
12665.185.31.64/2665.185.31.65 to 65.185.31.12665.185.31.12762
12765.185.31.128/2665.185.31.129 to 65.185.31.19065.185.31.19162
12865.185.31.192/2665.185.31.193 to 65.185.31.25465.185.31.25562
12965.185.32.0/2665.185.32.1 to 65.185.32.6265.185.32.6362
13065.185.32.64/2665.185.32.65 to 65.185.32.12665.185.32.12762
13165.185.32.128/2665.185.32.129 to 65.185.32.19065.185.32.19162
13265.185.32.192/2665.185.32.193 to 65.185.32.25465.185.32.25562
13365.185.33.0/2665.185.33.1 to 65.185.33.6265.185.33.6362
13465.185.33.64/2665.185.33.65 to 65.185.33.12665.185.33.12762
13565.185.33.128/2665.185.33.129 to 65.185.33.19065.185.33.19162
13665.185.33.192/2665.185.33.193 to 65.185.33.25465.185.33.25562
13765.185.34.0/2665.185.34.1 to 65.185.34.6265.185.34.6362
13865.185.34.64/2665.185.34.65 to 65.185.34.12665.185.34.12762
13965.185.34.128/2665.185.34.129 to 65.185.34.19065.185.34.19162
14065.185.34.192/2665.185.34.193 to 65.185.34.25465.185.34.25562
14165.185.35.0/2665.185.35.1 to 65.185.35.6265.185.35.6362
14265.185.35.64/2665.185.35.65 to 65.185.35.12665.185.35.12762
14365.185.35.128/2665.185.35.129 to 65.185.35.19065.185.35.19162
14465.185.35.192/2665.185.35.193 to 65.185.35.25465.185.35.25562
14565.185.36.0/2665.185.36.1 to 65.185.36.6265.185.36.6362
14665.185.36.64/2665.185.36.65 to 65.185.36.12665.185.36.12762
14765.185.36.128/2665.185.36.129 to 65.185.36.19065.185.36.19162
14865.185.36.192/2665.185.36.193 to 65.185.36.25465.185.36.25562
14965.185.37.0/2665.185.37.1 to 65.185.37.6265.185.37.6362
15065.185.37.64/2665.185.37.65 to 65.185.37.12665.185.37.12762
15165.185.37.128/2665.185.37.129 to 65.185.37.19065.185.37.19162
15265.185.37.192/2665.185.37.193 to 65.185.37.25465.185.37.25562
15365.185.38.0/2665.185.38.1 to 65.185.38.6265.185.38.6362
15465.185.38.64/2665.185.38.65 to 65.185.38.12665.185.38.12762
15565.185.38.128/2665.185.38.129 to 65.185.38.19065.185.38.19162
15665.185.38.192/2665.185.38.193 to 65.185.38.25465.185.38.25562
15765.185.39.0/2665.185.39.1 to 65.185.39.6265.185.39.6362
15865.185.39.64/2665.185.39.65 to 65.185.39.12665.185.39.12762
15965.185.39.128/2665.185.39.129 to 65.185.39.19065.185.39.19162
16065.185.39.192/2665.185.39.193 to 65.185.39.25465.185.39.25562
16165.185.40.0/2665.185.40.1 to 65.185.40.6265.185.40.6362
16265.185.40.64/2665.185.40.65 to 65.185.40.12665.185.40.12762
16365.185.40.128/2665.185.40.129 to 65.185.40.19065.185.40.19162
16465.185.40.192/2665.185.40.193 to 65.185.40.25465.185.40.25562
16565.185.41.0/2665.185.41.1 to 65.185.41.6265.185.41.6362
16665.185.41.64/2665.185.41.65 to 65.185.41.12665.185.41.12762
16765.185.41.128/2665.185.41.129 to 65.185.41.19065.185.41.19162
16865.185.41.192/2665.185.41.193 to 65.185.41.25465.185.41.25562
16965.185.42.0/2665.185.42.1 to 65.185.42.6265.185.42.6362
17065.185.42.64/2665.185.42.65 to 65.185.42.12665.185.42.12762
17165.185.42.128/2665.185.42.129 to 65.185.42.19065.185.42.19162
17265.185.42.192/2665.185.42.193 to 65.185.42.25465.185.42.25562
17365.185.43.0/2665.185.43.1 to 65.185.43.6265.185.43.6362
17465.185.43.64/2665.185.43.65 to 65.185.43.12665.185.43.12762
17565.185.43.128/2665.185.43.129 to 65.185.43.19065.185.43.19162
17665.185.43.192/2665.185.43.193 to 65.185.43.25465.185.43.25562
17765.185.44.0/2665.185.44.1 to 65.185.44.6265.185.44.6362
17865.185.44.64/2665.185.44.65 to 65.185.44.12665.185.44.12762
17965.185.44.128/2665.185.44.129 to 65.185.44.19065.185.44.19162
18065.185.44.192/2665.185.44.193 to 65.185.44.25465.185.44.25562
18165.185.45.0/2665.185.45.1 to 65.185.45.6265.185.45.6362
18265.185.45.64/2665.185.45.65 to 65.185.45.12665.185.45.12762
18365.185.45.128/2665.185.45.129 to 65.185.45.19065.185.45.19162
18465.185.45.192/2665.185.45.193 to 65.185.45.25465.185.45.25562
18565.185.46.0/2665.185.46.1 to 65.185.46.6265.185.46.6362
18665.185.46.64/2665.185.46.65 to 65.185.46.12665.185.46.12762
18765.185.46.128/2665.185.46.129 to 65.185.46.19065.185.46.19162
18865.185.46.192/2665.185.46.193 to 65.185.46.25465.185.46.25562
18965.185.47.0/2665.185.47.1 to 65.185.47.6265.185.47.6362
19065.185.47.64/2665.185.47.65 to 65.185.47.12665.185.47.12762
19165.185.47.128/2665.185.47.129 to 65.185.47.19065.185.47.19162
19265.185.47.192/2665.185.47.193 to 65.185.47.25465.185.47.25562
19365.185.48.0/2665.185.48.1 to 65.185.48.6265.185.48.6362
19465.185.48.64/2665.185.48.65 to 65.185.48.12665.185.48.12762
19565.185.48.128/2665.185.48.129 to 65.185.48.19065.185.48.19162
19665.185.48.192/2665.185.48.193 to 65.185.48.25465.185.48.25562
19765.185.49.0/2665.185.49.1 to 65.185.49.6265.185.49.6362
19865.185.49.64/2665.185.49.65 to 65.185.49.12665.185.49.12762
19965.185.49.128/2665.185.49.129 to 65.185.49.19065.185.49.19162
20065.185.49.192/2665.185.49.193 to 65.185.49.25465.185.49.25562
20165.185.50.0/2665.185.50.1 to 65.185.50.6265.185.50.6362
20265.185.50.64/2665.185.50.65 to 65.185.50.12665.185.50.12762
20365.185.50.128/2665.185.50.129 to 65.185.50.19065.185.50.19162
20465.185.50.192/2665.185.50.193 to 65.185.50.25465.185.50.25562
20565.185.51.0/2665.185.51.1 to 65.185.51.6265.185.51.6362
20665.185.51.64/2665.185.51.65 to 65.185.51.12665.185.51.12762
20765.185.51.128/2665.185.51.129 to 65.185.51.19065.185.51.19162
20865.185.51.192/2665.185.51.193 to 65.185.51.25465.185.51.25562
20965.185.52.0/2665.185.52.1 to 65.185.52.6265.185.52.6362
21065.185.52.64/2665.185.52.65 to 65.185.52.12665.185.52.12762
21165.185.52.128/2665.185.52.129 to 65.185.52.19065.185.52.19162
21265.185.52.192/2665.185.52.193 to 65.185.52.25465.185.52.25562
21365.185.53.0/2665.185.53.1 to 65.185.53.6265.185.53.6362
21465.185.53.64/2665.185.53.65 to 65.185.53.12665.185.53.12762
21565.185.53.128/2665.185.53.129 to 65.185.53.19065.185.53.19162
21665.185.53.192/2665.185.53.193 to 65.185.53.25465.185.53.25562
21765.185.54.0/2665.185.54.1 to 65.185.54.6265.185.54.6362
21865.185.54.64/2665.185.54.65 to 65.185.54.12665.185.54.12762
21965.185.54.128/2665.185.54.129 to 65.185.54.19065.185.54.19162
22065.185.54.192/2665.185.54.193 to 65.185.54.25465.185.54.25562
22165.185.55.0/2665.185.55.1 to 65.185.55.6265.185.55.6362
22265.185.55.64/2665.185.55.65 to 65.185.55.12665.185.55.12762
22365.185.55.128/2665.185.55.129 to 65.185.55.19065.185.55.19162
22465.185.55.192/2665.185.55.193 to 65.185.55.25465.185.55.25562
22565.185.56.0/2665.185.56.1 to 65.185.56.6265.185.56.6362
22665.185.56.64/2665.185.56.65 to 65.185.56.12665.185.56.12762
22765.185.56.128/2665.185.56.129 to 65.185.56.19065.185.56.19162
22865.185.56.192/2665.185.56.193 to 65.185.56.25465.185.56.25562
22965.185.57.0/2665.185.57.1 to 65.185.57.6265.185.57.6362
23065.185.57.64/2665.185.57.65 to 65.185.57.12665.185.57.12762
23165.185.57.128/2665.185.57.129 to 65.185.57.19065.185.57.19162
23265.185.57.192/2665.185.57.193 to 65.185.57.25465.185.57.25562
23365.185.58.0/2665.185.58.1 to 65.185.58.6265.185.58.6362
23465.185.58.64/2665.185.58.65 to 65.185.58.12665.185.58.12762
23565.185.58.128/2665.185.58.129 to 65.185.58.19065.185.58.19162
23665.185.58.192/2665.185.58.193 to 65.185.58.25465.185.58.25562
23765.185.59.0/2665.185.59.1 to 65.185.59.6265.185.59.6362
23865.185.59.64/2665.185.59.65 to 65.185.59.12665.185.59.12762
23965.185.59.128/2665.185.59.129 to 65.185.59.19065.185.59.19162
24065.185.59.192/2665.185.59.193 to 65.185.59.25465.185.59.25562
24165.185.60.0/2665.185.60.1 to 65.185.60.6265.185.60.6362
24265.185.60.64/2665.185.60.65 to 65.185.60.12665.185.60.12762
24365.185.60.128/2665.185.60.129 to 65.185.60.19065.185.60.19162
24465.185.60.192/2665.185.60.193 to 65.185.60.25465.185.60.25562
24565.185.61.0/2665.185.61.1 to 65.185.61.6265.185.61.6362
24665.185.61.64/2665.185.61.65 to 65.185.61.12665.185.61.12762
24765.185.61.128/2665.185.61.129 to 65.185.61.19065.185.61.19162
24865.185.61.192/2665.185.61.193 to 65.185.61.25465.185.61.25562
24965.185.62.0/2665.185.62.1 to 65.185.62.6265.185.62.6362
25065.185.62.64/2665.185.62.65 to 65.185.62.12665.185.62.12762
25165.185.62.128/2665.185.62.129 to 65.185.62.19065.185.62.19162
25265.185.62.192/2665.185.62.193 to 65.185.62.25465.185.62.25562
25365.185.63.0/2665.185.63.1 to 65.185.63.6265.185.63.6362
25465.185.63.64/2665.185.63.65 to 65.185.63.12665.185.63.12762
25565.185.63.128/2665.185.63.129 to 65.185.63.19065.185.63.19162
25665.185.63.192/2665.185.63.193 to 65.185.63.25465.185.63.25562

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.