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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.

Network66.4.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
66.4.0.0
Broadcast address
66.4.127.255
First usable
66.4.0.1
Last usable
66.4.127.254
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 42040000 · Integer 1107558400 to 1107591167
Reverse DNS zones
0.4.66.in-addr.arpa
1.4.66.in-addr.arpa
2.4.66.in-addr.arpa
3.4.66.in-addr.arpa
4.4.66.in-addr.arpa
5.4.66.in-addr.arpa
6.4.66.in-addr.arpa
7.4.66.in-addr.arpa
8.4.66.in-addr.arpa
9.4.66.in-addr.arpa
10.4.66.in-addr.arpa
11.4.66.in-addr.arpa
12.4.66.in-addr.arpa
13.4.66.in-addr.arpa
14.4.66.in-addr.arpa
15.4.66.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
Address01000010.00000100.00000000.0000000066.4.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network01000010.00000100.00000000.0000000066.4.0.0
Broadcast01000010.00000100.01111111.1111111166.4.127.255
Split into smaller subnets/25
/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)

66.4.0.0/17 makes 256 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
166.4.0.0/2566.4.0.1 to 66.4.0.12666.4.0.127126
266.4.0.128/2566.4.0.129 to 66.4.0.25466.4.0.255126
366.4.1.0/2566.4.1.1 to 66.4.1.12666.4.1.127126
466.4.1.128/2566.4.1.129 to 66.4.1.25466.4.1.255126
566.4.2.0/2566.4.2.1 to 66.4.2.12666.4.2.127126
666.4.2.128/2566.4.2.129 to 66.4.2.25466.4.2.255126
766.4.3.0/2566.4.3.1 to 66.4.3.12666.4.3.127126
866.4.3.128/2566.4.3.129 to 66.4.3.25466.4.3.255126
966.4.4.0/2566.4.4.1 to 66.4.4.12666.4.4.127126
1066.4.4.128/2566.4.4.129 to 66.4.4.25466.4.4.255126
1166.4.5.0/2566.4.5.1 to 66.4.5.12666.4.5.127126
1266.4.5.128/2566.4.5.129 to 66.4.5.25466.4.5.255126
1366.4.6.0/2566.4.6.1 to 66.4.6.12666.4.6.127126
1466.4.6.128/2566.4.6.129 to 66.4.6.25466.4.6.255126
1566.4.7.0/2566.4.7.1 to 66.4.7.12666.4.7.127126
1666.4.7.128/2566.4.7.129 to 66.4.7.25466.4.7.255126
1766.4.8.0/2566.4.8.1 to 66.4.8.12666.4.8.127126
1866.4.8.128/2566.4.8.129 to 66.4.8.25466.4.8.255126
1966.4.9.0/2566.4.9.1 to 66.4.9.12666.4.9.127126
2066.4.9.128/2566.4.9.129 to 66.4.9.25466.4.9.255126
2166.4.10.0/2566.4.10.1 to 66.4.10.12666.4.10.127126
2266.4.10.128/2566.4.10.129 to 66.4.10.25466.4.10.255126
2366.4.11.0/2566.4.11.1 to 66.4.11.12666.4.11.127126
2466.4.11.128/2566.4.11.129 to 66.4.11.25466.4.11.255126
2566.4.12.0/2566.4.12.1 to 66.4.12.12666.4.12.127126
2666.4.12.128/2566.4.12.129 to 66.4.12.25466.4.12.255126
2766.4.13.0/2566.4.13.1 to 66.4.13.12666.4.13.127126
2866.4.13.128/2566.4.13.129 to 66.4.13.25466.4.13.255126
2966.4.14.0/2566.4.14.1 to 66.4.14.12666.4.14.127126
3066.4.14.128/2566.4.14.129 to 66.4.14.25466.4.14.255126
3166.4.15.0/2566.4.15.1 to 66.4.15.12666.4.15.127126
3266.4.15.128/2566.4.15.129 to 66.4.15.25466.4.15.255126
3366.4.16.0/2566.4.16.1 to 66.4.16.12666.4.16.127126
3466.4.16.128/2566.4.16.129 to 66.4.16.25466.4.16.255126
3566.4.17.0/2566.4.17.1 to 66.4.17.12666.4.17.127126
3666.4.17.128/2566.4.17.129 to 66.4.17.25466.4.17.255126
3766.4.18.0/2566.4.18.1 to 66.4.18.12666.4.18.127126
3866.4.18.128/2566.4.18.129 to 66.4.18.25466.4.18.255126
3966.4.19.0/2566.4.19.1 to 66.4.19.12666.4.19.127126
4066.4.19.128/2566.4.19.129 to 66.4.19.25466.4.19.255126
4166.4.20.0/2566.4.20.1 to 66.4.20.12666.4.20.127126
4266.4.20.128/2566.4.20.129 to 66.4.20.25466.4.20.255126
4366.4.21.0/2566.4.21.1 to 66.4.21.12666.4.21.127126
4466.4.21.128/2566.4.21.129 to 66.4.21.25466.4.21.255126
4566.4.22.0/2566.4.22.1 to 66.4.22.12666.4.22.127126
4666.4.22.128/2566.4.22.129 to 66.4.22.25466.4.22.255126
4766.4.23.0/2566.4.23.1 to 66.4.23.12666.4.23.127126
4866.4.23.128/2566.4.23.129 to 66.4.23.25466.4.23.255126
4966.4.24.0/2566.4.24.1 to 66.4.24.12666.4.24.127126
5066.4.24.128/2566.4.24.129 to 66.4.24.25466.4.24.255126
5166.4.25.0/2566.4.25.1 to 66.4.25.12666.4.25.127126
5266.4.25.128/2566.4.25.129 to 66.4.25.25466.4.25.255126
5366.4.26.0/2566.4.26.1 to 66.4.26.12666.4.26.127126
5466.4.26.128/2566.4.26.129 to 66.4.26.25466.4.26.255126
5566.4.27.0/2566.4.27.1 to 66.4.27.12666.4.27.127126
5666.4.27.128/2566.4.27.129 to 66.4.27.25466.4.27.255126
5766.4.28.0/2566.4.28.1 to 66.4.28.12666.4.28.127126
5866.4.28.128/2566.4.28.129 to 66.4.28.25466.4.28.255126
5966.4.29.0/2566.4.29.1 to 66.4.29.12666.4.29.127126
6066.4.29.128/2566.4.29.129 to 66.4.29.25466.4.29.255126
6166.4.30.0/2566.4.30.1 to 66.4.30.12666.4.30.127126
6266.4.30.128/2566.4.30.129 to 66.4.30.25466.4.30.255126
6366.4.31.0/2566.4.31.1 to 66.4.31.12666.4.31.127126
6466.4.31.128/2566.4.31.129 to 66.4.31.25466.4.31.255126
6566.4.32.0/2566.4.32.1 to 66.4.32.12666.4.32.127126
6666.4.32.128/2566.4.32.129 to 66.4.32.25466.4.32.255126
6766.4.33.0/2566.4.33.1 to 66.4.33.12666.4.33.127126
6866.4.33.128/2566.4.33.129 to 66.4.33.25466.4.33.255126
6966.4.34.0/2566.4.34.1 to 66.4.34.12666.4.34.127126
7066.4.34.128/2566.4.34.129 to 66.4.34.25466.4.34.255126
7166.4.35.0/2566.4.35.1 to 66.4.35.12666.4.35.127126
7266.4.35.128/2566.4.35.129 to 66.4.35.25466.4.35.255126
7366.4.36.0/2566.4.36.1 to 66.4.36.12666.4.36.127126
7466.4.36.128/2566.4.36.129 to 66.4.36.25466.4.36.255126
7566.4.37.0/2566.4.37.1 to 66.4.37.12666.4.37.127126
7666.4.37.128/2566.4.37.129 to 66.4.37.25466.4.37.255126
7766.4.38.0/2566.4.38.1 to 66.4.38.12666.4.38.127126
7866.4.38.128/2566.4.38.129 to 66.4.38.25466.4.38.255126
7966.4.39.0/2566.4.39.1 to 66.4.39.12666.4.39.127126
8066.4.39.128/2566.4.39.129 to 66.4.39.25466.4.39.255126
8166.4.40.0/2566.4.40.1 to 66.4.40.12666.4.40.127126
8266.4.40.128/2566.4.40.129 to 66.4.40.25466.4.40.255126
8366.4.41.0/2566.4.41.1 to 66.4.41.12666.4.41.127126
8466.4.41.128/2566.4.41.129 to 66.4.41.25466.4.41.255126
8566.4.42.0/2566.4.42.1 to 66.4.42.12666.4.42.127126
8666.4.42.128/2566.4.42.129 to 66.4.42.25466.4.42.255126
8766.4.43.0/2566.4.43.1 to 66.4.43.12666.4.43.127126
8866.4.43.128/2566.4.43.129 to 66.4.43.25466.4.43.255126
8966.4.44.0/2566.4.44.1 to 66.4.44.12666.4.44.127126
9066.4.44.128/2566.4.44.129 to 66.4.44.25466.4.44.255126
9166.4.45.0/2566.4.45.1 to 66.4.45.12666.4.45.127126
9266.4.45.128/2566.4.45.129 to 66.4.45.25466.4.45.255126
9366.4.46.0/2566.4.46.1 to 66.4.46.12666.4.46.127126
9466.4.46.128/2566.4.46.129 to 66.4.46.25466.4.46.255126
9566.4.47.0/2566.4.47.1 to 66.4.47.12666.4.47.127126
9666.4.47.128/2566.4.47.129 to 66.4.47.25466.4.47.255126
9766.4.48.0/2566.4.48.1 to 66.4.48.12666.4.48.127126
9866.4.48.128/2566.4.48.129 to 66.4.48.25466.4.48.255126
9966.4.49.0/2566.4.49.1 to 66.4.49.12666.4.49.127126
10066.4.49.128/2566.4.49.129 to 66.4.49.25466.4.49.255126
10166.4.50.0/2566.4.50.1 to 66.4.50.12666.4.50.127126
10266.4.50.128/2566.4.50.129 to 66.4.50.25466.4.50.255126
10366.4.51.0/2566.4.51.1 to 66.4.51.12666.4.51.127126
10466.4.51.128/2566.4.51.129 to 66.4.51.25466.4.51.255126
10566.4.52.0/2566.4.52.1 to 66.4.52.12666.4.52.127126
10666.4.52.128/2566.4.52.129 to 66.4.52.25466.4.52.255126
10766.4.53.0/2566.4.53.1 to 66.4.53.12666.4.53.127126
10866.4.53.128/2566.4.53.129 to 66.4.53.25466.4.53.255126
10966.4.54.0/2566.4.54.1 to 66.4.54.12666.4.54.127126
11066.4.54.128/2566.4.54.129 to 66.4.54.25466.4.54.255126
11166.4.55.0/2566.4.55.1 to 66.4.55.12666.4.55.127126
11266.4.55.128/2566.4.55.129 to 66.4.55.25466.4.55.255126
11366.4.56.0/2566.4.56.1 to 66.4.56.12666.4.56.127126
11466.4.56.128/2566.4.56.129 to 66.4.56.25466.4.56.255126
11566.4.57.0/2566.4.57.1 to 66.4.57.12666.4.57.127126
11666.4.57.128/2566.4.57.129 to 66.4.57.25466.4.57.255126
11766.4.58.0/2566.4.58.1 to 66.4.58.12666.4.58.127126
11866.4.58.128/2566.4.58.129 to 66.4.58.25466.4.58.255126
11966.4.59.0/2566.4.59.1 to 66.4.59.12666.4.59.127126
12066.4.59.128/2566.4.59.129 to 66.4.59.25466.4.59.255126
12166.4.60.0/2566.4.60.1 to 66.4.60.12666.4.60.127126
12266.4.60.128/2566.4.60.129 to 66.4.60.25466.4.60.255126
12366.4.61.0/2566.4.61.1 to 66.4.61.12666.4.61.127126
12466.4.61.128/2566.4.61.129 to 66.4.61.25466.4.61.255126
12566.4.62.0/2566.4.62.1 to 66.4.62.12666.4.62.127126
12666.4.62.128/2566.4.62.129 to 66.4.62.25466.4.62.255126
12766.4.63.0/2566.4.63.1 to 66.4.63.12666.4.63.127126
12866.4.63.128/2566.4.63.129 to 66.4.63.25466.4.63.255126
12966.4.64.0/2566.4.64.1 to 66.4.64.12666.4.64.127126
13066.4.64.128/2566.4.64.129 to 66.4.64.25466.4.64.255126
13166.4.65.0/2566.4.65.1 to 66.4.65.12666.4.65.127126
13266.4.65.128/2566.4.65.129 to 66.4.65.25466.4.65.255126
13366.4.66.0/2566.4.66.1 to 66.4.66.12666.4.66.127126
13466.4.66.128/2566.4.66.129 to 66.4.66.25466.4.66.255126
13566.4.67.0/2566.4.67.1 to 66.4.67.12666.4.67.127126
13666.4.67.128/2566.4.67.129 to 66.4.67.25466.4.67.255126
13766.4.68.0/2566.4.68.1 to 66.4.68.12666.4.68.127126
13866.4.68.128/2566.4.68.129 to 66.4.68.25466.4.68.255126
13966.4.69.0/2566.4.69.1 to 66.4.69.12666.4.69.127126
14066.4.69.128/2566.4.69.129 to 66.4.69.25466.4.69.255126
14166.4.70.0/2566.4.70.1 to 66.4.70.12666.4.70.127126
14266.4.70.128/2566.4.70.129 to 66.4.70.25466.4.70.255126
14366.4.71.0/2566.4.71.1 to 66.4.71.12666.4.71.127126
14466.4.71.128/2566.4.71.129 to 66.4.71.25466.4.71.255126
14566.4.72.0/2566.4.72.1 to 66.4.72.12666.4.72.127126
14666.4.72.128/2566.4.72.129 to 66.4.72.25466.4.72.255126
14766.4.73.0/2566.4.73.1 to 66.4.73.12666.4.73.127126
14866.4.73.128/2566.4.73.129 to 66.4.73.25466.4.73.255126
14966.4.74.0/2566.4.74.1 to 66.4.74.12666.4.74.127126
15066.4.74.128/2566.4.74.129 to 66.4.74.25466.4.74.255126
15166.4.75.0/2566.4.75.1 to 66.4.75.12666.4.75.127126
15266.4.75.128/2566.4.75.129 to 66.4.75.25466.4.75.255126
15366.4.76.0/2566.4.76.1 to 66.4.76.12666.4.76.127126
15466.4.76.128/2566.4.76.129 to 66.4.76.25466.4.76.255126
15566.4.77.0/2566.4.77.1 to 66.4.77.12666.4.77.127126
15666.4.77.128/2566.4.77.129 to 66.4.77.25466.4.77.255126
15766.4.78.0/2566.4.78.1 to 66.4.78.12666.4.78.127126
15866.4.78.128/2566.4.78.129 to 66.4.78.25466.4.78.255126
15966.4.79.0/2566.4.79.1 to 66.4.79.12666.4.79.127126
16066.4.79.128/2566.4.79.129 to 66.4.79.25466.4.79.255126
16166.4.80.0/2566.4.80.1 to 66.4.80.12666.4.80.127126
16266.4.80.128/2566.4.80.129 to 66.4.80.25466.4.80.255126
16366.4.81.0/2566.4.81.1 to 66.4.81.12666.4.81.127126
16466.4.81.128/2566.4.81.129 to 66.4.81.25466.4.81.255126
16566.4.82.0/2566.4.82.1 to 66.4.82.12666.4.82.127126
16666.4.82.128/2566.4.82.129 to 66.4.82.25466.4.82.255126
16766.4.83.0/2566.4.83.1 to 66.4.83.12666.4.83.127126
16866.4.83.128/2566.4.83.129 to 66.4.83.25466.4.83.255126
16966.4.84.0/2566.4.84.1 to 66.4.84.12666.4.84.127126
17066.4.84.128/2566.4.84.129 to 66.4.84.25466.4.84.255126
17166.4.85.0/2566.4.85.1 to 66.4.85.12666.4.85.127126
17266.4.85.128/2566.4.85.129 to 66.4.85.25466.4.85.255126
17366.4.86.0/2566.4.86.1 to 66.4.86.12666.4.86.127126
17466.4.86.128/2566.4.86.129 to 66.4.86.25466.4.86.255126
17566.4.87.0/2566.4.87.1 to 66.4.87.12666.4.87.127126
17666.4.87.128/2566.4.87.129 to 66.4.87.25466.4.87.255126
17766.4.88.0/2566.4.88.1 to 66.4.88.12666.4.88.127126
17866.4.88.128/2566.4.88.129 to 66.4.88.25466.4.88.255126
17966.4.89.0/2566.4.89.1 to 66.4.89.12666.4.89.127126
18066.4.89.128/2566.4.89.129 to 66.4.89.25466.4.89.255126
18166.4.90.0/2566.4.90.1 to 66.4.90.12666.4.90.127126
18266.4.90.128/2566.4.90.129 to 66.4.90.25466.4.90.255126
18366.4.91.0/2566.4.91.1 to 66.4.91.12666.4.91.127126
18466.4.91.128/2566.4.91.129 to 66.4.91.25466.4.91.255126
18566.4.92.0/2566.4.92.1 to 66.4.92.12666.4.92.127126
18666.4.92.128/2566.4.92.129 to 66.4.92.25466.4.92.255126
18766.4.93.0/2566.4.93.1 to 66.4.93.12666.4.93.127126
18866.4.93.128/2566.4.93.129 to 66.4.93.25466.4.93.255126
18966.4.94.0/2566.4.94.1 to 66.4.94.12666.4.94.127126
19066.4.94.128/2566.4.94.129 to 66.4.94.25466.4.94.255126
19166.4.95.0/2566.4.95.1 to 66.4.95.12666.4.95.127126
19266.4.95.128/2566.4.95.129 to 66.4.95.25466.4.95.255126
19366.4.96.0/2566.4.96.1 to 66.4.96.12666.4.96.127126
19466.4.96.128/2566.4.96.129 to 66.4.96.25466.4.96.255126
19566.4.97.0/2566.4.97.1 to 66.4.97.12666.4.97.127126
19666.4.97.128/2566.4.97.129 to 66.4.97.25466.4.97.255126
19766.4.98.0/2566.4.98.1 to 66.4.98.12666.4.98.127126
19866.4.98.128/2566.4.98.129 to 66.4.98.25466.4.98.255126
19966.4.99.0/2566.4.99.1 to 66.4.99.12666.4.99.127126
20066.4.99.128/2566.4.99.129 to 66.4.99.25466.4.99.255126
20166.4.100.0/2566.4.100.1 to 66.4.100.12666.4.100.127126
20266.4.100.128/2566.4.100.129 to 66.4.100.25466.4.100.255126
20366.4.101.0/2566.4.101.1 to 66.4.101.12666.4.101.127126
20466.4.101.128/2566.4.101.129 to 66.4.101.25466.4.101.255126
20566.4.102.0/2566.4.102.1 to 66.4.102.12666.4.102.127126
20666.4.102.128/2566.4.102.129 to 66.4.102.25466.4.102.255126
20766.4.103.0/2566.4.103.1 to 66.4.103.12666.4.103.127126
20866.4.103.128/2566.4.103.129 to 66.4.103.25466.4.103.255126
20966.4.104.0/2566.4.104.1 to 66.4.104.12666.4.104.127126
21066.4.104.128/2566.4.104.129 to 66.4.104.25466.4.104.255126
21166.4.105.0/2566.4.105.1 to 66.4.105.12666.4.105.127126
21266.4.105.128/2566.4.105.129 to 66.4.105.25466.4.105.255126
21366.4.106.0/2566.4.106.1 to 66.4.106.12666.4.106.127126
21466.4.106.128/2566.4.106.129 to 66.4.106.25466.4.106.255126
21566.4.107.0/2566.4.107.1 to 66.4.107.12666.4.107.127126
21666.4.107.128/2566.4.107.129 to 66.4.107.25466.4.107.255126
21766.4.108.0/2566.4.108.1 to 66.4.108.12666.4.108.127126
21866.4.108.128/2566.4.108.129 to 66.4.108.25466.4.108.255126
21966.4.109.0/2566.4.109.1 to 66.4.109.12666.4.109.127126
22066.4.109.128/2566.4.109.129 to 66.4.109.25466.4.109.255126
22166.4.110.0/2566.4.110.1 to 66.4.110.12666.4.110.127126
22266.4.110.128/2566.4.110.129 to 66.4.110.25466.4.110.255126
22366.4.111.0/2566.4.111.1 to 66.4.111.12666.4.111.127126
22466.4.111.128/2566.4.111.129 to 66.4.111.25466.4.111.255126
22566.4.112.0/2566.4.112.1 to 66.4.112.12666.4.112.127126
22666.4.112.128/2566.4.112.129 to 66.4.112.25466.4.112.255126
22766.4.113.0/2566.4.113.1 to 66.4.113.12666.4.113.127126
22866.4.113.128/2566.4.113.129 to 66.4.113.25466.4.113.255126
22966.4.114.0/2566.4.114.1 to 66.4.114.12666.4.114.127126
23066.4.114.128/2566.4.114.129 to 66.4.114.25466.4.114.255126
23166.4.115.0/2566.4.115.1 to 66.4.115.12666.4.115.127126
23266.4.115.128/2566.4.115.129 to 66.4.115.25466.4.115.255126
23366.4.116.0/2566.4.116.1 to 66.4.116.12666.4.116.127126
23466.4.116.128/2566.4.116.129 to 66.4.116.25466.4.116.255126
23566.4.117.0/2566.4.117.1 to 66.4.117.12666.4.117.127126
23666.4.117.128/2566.4.117.129 to 66.4.117.25466.4.117.255126
23766.4.118.0/2566.4.118.1 to 66.4.118.12666.4.118.127126
23866.4.118.128/2566.4.118.129 to 66.4.118.25466.4.118.255126
23966.4.119.0/2566.4.119.1 to 66.4.119.12666.4.119.127126
24066.4.119.128/2566.4.119.129 to 66.4.119.25466.4.119.255126
24166.4.120.0/2566.4.120.1 to 66.4.120.12666.4.120.127126
24266.4.120.128/2566.4.120.129 to 66.4.120.25466.4.120.255126
24366.4.121.0/2566.4.121.1 to 66.4.121.12666.4.121.127126
24466.4.121.128/2566.4.121.129 to 66.4.121.25466.4.121.255126
24566.4.122.0/2566.4.122.1 to 66.4.122.12666.4.122.127126
24666.4.122.128/2566.4.122.129 to 66.4.122.25466.4.122.255126
24766.4.123.0/2566.4.123.1 to 66.4.123.12666.4.123.127126
24866.4.123.128/2566.4.123.129 to 66.4.123.25466.4.123.255126
24966.4.124.0/2566.4.124.1 to 66.4.124.12666.4.124.127126
25066.4.124.128/2566.4.124.129 to 66.4.124.25466.4.124.255126
25166.4.125.0/2566.4.125.1 to 66.4.125.12666.4.125.127126
25266.4.125.128/2566.4.125.129 to 66.4.125.25466.4.125.255126
25366.4.126.0/2566.4.126.1 to 66.4.126.12666.4.126.127126
25466.4.126.128/2566.4.126.129 to 66.4.126.25466.4.126.255126
25566.4.127.0/2566.4.127.1 to 66.4.127.12666.4.127.127126
25666.4.127.128/2566.4.127.129 to 66.4.127.25466.4.127.255126

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.