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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.

Network64.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
64.0.0.0
Broadcast address
64.127.255.255
First usable
64.0.0.1
Last usable
64.127.255.254
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 40000000 · Integer 1073741824 to 1082130431
Reverse DNS zones
0.64.in-addr.arpa
1.64.in-addr.arpa
2.64.in-addr.arpa
3.64.in-addr.arpa
4.64.in-addr.arpa
5.64.in-addr.arpa
6.64.in-addr.arpa
7.64.in-addr.arpa
8.64.in-addr.arpa
9.64.in-addr.arpa
10.64.in-addr.arpa
11.64.in-addr.arpa
12.64.in-addr.arpa
13.64.in-addr.arpa
14.64.in-addr.arpa
15.64.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
Address01000000.00000000.00000000.0000000064.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01000000.00000000.00000000.0000000064.0.0.0
Broadcast01000000.01111111.11111111.1111111164.127.255.255
Split into smaller subnets/17
/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)

64.0.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.0.0.0/1764.0.0.1 to 64.0.127.25464.0.127.25532,766
264.0.128.0/1764.0.128.1 to 64.0.255.25464.0.255.25532,766
364.1.0.0/1764.1.0.1 to 64.1.127.25464.1.127.25532,766
464.1.128.0/1764.1.128.1 to 64.1.255.25464.1.255.25532,766
564.2.0.0/1764.2.0.1 to 64.2.127.25464.2.127.25532,766
664.2.128.0/1764.2.128.1 to 64.2.255.25464.2.255.25532,766
764.3.0.0/1764.3.0.1 to 64.3.127.25464.3.127.25532,766
864.3.128.0/1764.3.128.1 to 64.3.255.25464.3.255.25532,766
964.4.0.0/1764.4.0.1 to 64.4.127.25464.4.127.25532,766
1064.4.128.0/1764.4.128.1 to 64.4.255.25464.4.255.25532,766
1164.5.0.0/1764.5.0.1 to 64.5.127.25464.5.127.25532,766
1264.5.128.0/1764.5.128.1 to 64.5.255.25464.5.255.25532,766
1364.6.0.0/1764.6.0.1 to 64.6.127.25464.6.127.25532,766
1464.6.128.0/1764.6.128.1 to 64.6.255.25464.6.255.25532,766
1564.7.0.0/1764.7.0.1 to 64.7.127.25464.7.127.25532,766
1664.7.128.0/1764.7.128.1 to 64.7.255.25464.7.255.25532,766
1764.8.0.0/1764.8.0.1 to 64.8.127.25464.8.127.25532,766
1864.8.128.0/1764.8.128.1 to 64.8.255.25464.8.255.25532,766
1964.9.0.0/1764.9.0.1 to 64.9.127.25464.9.127.25532,766
2064.9.128.0/1764.9.128.1 to 64.9.255.25464.9.255.25532,766
2164.10.0.0/1764.10.0.1 to 64.10.127.25464.10.127.25532,766
2264.10.128.0/1764.10.128.1 to 64.10.255.25464.10.255.25532,766
2364.11.0.0/1764.11.0.1 to 64.11.127.25464.11.127.25532,766
2464.11.128.0/1764.11.128.1 to 64.11.255.25464.11.255.25532,766
2564.12.0.0/1764.12.0.1 to 64.12.127.25464.12.127.25532,766
2664.12.128.0/1764.12.128.1 to 64.12.255.25464.12.255.25532,766
2764.13.0.0/1764.13.0.1 to 64.13.127.25464.13.127.25532,766
2864.13.128.0/1764.13.128.1 to 64.13.255.25464.13.255.25532,766
2964.14.0.0/1764.14.0.1 to 64.14.127.25464.14.127.25532,766
3064.14.128.0/1764.14.128.1 to 64.14.255.25464.14.255.25532,766
3164.15.0.0/1764.15.0.1 to 64.15.127.25464.15.127.25532,766
3264.15.128.0/1764.15.128.1 to 64.15.255.25464.15.255.25532,766
3364.16.0.0/1764.16.0.1 to 64.16.127.25464.16.127.25532,766
3464.16.128.0/1764.16.128.1 to 64.16.255.25464.16.255.25532,766
3564.17.0.0/1764.17.0.1 to 64.17.127.25464.17.127.25532,766
3664.17.128.0/1764.17.128.1 to 64.17.255.25464.17.255.25532,766
3764.18.0.0/1764.18.0.1 to 64.18.127.25464.18.127.25532,766
3864.18.128.0/1764.18.128.1 to 64.18.255.25464.18.255.25532,766
3964.19.0.0/1764.19.0.1 to 64.19.127.25464.19.127.25532,766
4064.19.128.0/1764.19.128.1 to 64.19.255.25464.19.255.25532,766
4164.20.0.0/1764.20.0.1 to 64.20.127.25464.20.127.25532,766
4264.20.128.0/1764.20.128.1 to 64.20.255.25464.20.255.25532,766
4364.21.0.0/1764.21.0.1 to 64.21.127.25464.21.127.25532,766
4464.21.128.0/1764.21.128.1 to 64.21.255.25464.21.255.25532,766
4564.22.0.0/1764.22.0.1 to 64.22.127.25464.22.127.25532,766
4664.22.128.0/1764.22.128.1 to 64.22.255.25464.22.255.25532,766
4764.23.0.0/1764.23.0.1 to 64.23.127.25464.23.127.25532,766
4864.23.128.0/1764.23.128.1 to 64.23.255.25464.23.255.25532,766
4964.24.0.0/1764.24.0.1 to 64.24.127.25464.24.127.25532,766
5064.24.128.0/1764.24.128.1 to 64.24.255.25464.24.255.25532,766
5164.25.0.0/1764.25.0.1 to 64.25.127.25464.25.127.25532,766
5264.25.128.0/1764.25.128.1 to 64.25.255.25464.25.255.25532,766
5364.26.0.0/1764.26.0.1 to 64.26.127.25464.26.127.25532,766
5464.26.128.0/1764.26.128.1 to 64.26.255.25464.26.255.25532,766
5564.27.0.0/1764.27.0.1 to 64.27.127.25464.27.127.25532,766
5664.27.128.0/1764.27.128.1 to 64.27.255.25464.27.255.25532,766
5764.28.0.0/1764.28.0.1 to 64.28.127.25464.28.127.25532,766
5864.28.128.0/1764.28.128.1 to 64.28.255.25464.28.255.25532,766
5964.29.0.0/1764.29.0.1 to 64.29.127.25464.29.127.25532,766
6064.29.128.0/1764.29.128.1 to 64.29.255.25464.29.255.25532,766
6164.30.0.0/1764.30.0.1 to 64.30.127.25464.30.127.25532,766
6264.30.128.0/1764.30.128.1 to 64.30.255.25464.30.255.25532,766
6364.31.0.0/1764.31.0.1 to 64.31.127.25464.31.127.25532,766
6464.31.128.0/1764.31.128.1 to 64.31.255.25464.31.255.25532,766
6564.32.0.0/1764.32.0.1 to 64.32.127.25464.32.127.25532,766
6664.32.128.0/1764.32.128.1 to 64.32.255.25464.32.255.25532,766
6764.33.0.0/1764.33.0.1 to 64.33.127.25464.33.127.25532,766
6864.33.128.0/1764.33.128.1 to 64.33.255.25464.33.255.25532,766
6964.34.0.0/1764.34.0.1 to 64.34.127.25464.34.127.25532,766
7064.34.128.0/1764.34.128.1 to 64.34.255.25464.34.255.25532,766
7164.35.0.0/1764.35.0.1 to 64.35.127.25464.35.127.25532,766
7264.35.128.0/1764.35.128.1 to 64.35.255.25464.35.255.25532,766
7364.36.0.0/1764.36.0.1 to 64.36.127.25464.36.127.25532,766
7464.36.128.0/1764.36.128.1 to 64.36.255.25464.36.255.25532,766
7564.37.0.0/1764.37.0.1 to 64.37.127.25464.37.127.25532,766
7664.37.128.0/1764.37.128.1 to 64.37.255.25464.37.255.25532,766
7764.38.0.0/1764.38.0.1 to 64.38.127.25464.38.127.25532,766
7864.38.128.0/1764.38.128.1 to 64.38.255.25464.38.255.25532,766
7964.39.0.0/1764.39.0.1 to 64.39.127.25464.39.127.25532,766
8064.39.128.0/1764.39.128.1 to 64.39.255.25464.39.255.25532,766
8164.40.0.0/1764.40.0.1 to 64.40.127.25464.40.127.25532,766
8264.40.128.0/1764.40.128.1 to 64.40.255.25464.40.255.25532,766
8364.41.0.0/1764.41.0.1 to 64.41.127.25464.41.127.25532,766
8464.41.128.0/1764.41.128.1 to 64.41.255.25464.41.255.25532,766
8564.42.0.0/1764.42.0.1 to 64.42.127.25464.42.127.25532,766
8664.42.128.0/1764.42.128.1 to 64.42.255.25464.42.255.25532,766
8764.43.0.0/1764.43.0.1 to 64.43.127.25464.43.127.25532,766
8864.43.128.0/1764.43.128.1 to 64.43.255.25464.43.255.25532,766
8964.44.0.0/1764.44.0.1 to 64.44.127.25464.44.127.25532,766
9064.44.128.0/1764.44.128.1 to 64.44.255.25464.44.255.25532,766
9164.45.0.0/1764.45.0.1 to 64.45.127.25464.45.127.25532,766
9264.45.128.0/1764.45.128.1 to 64.45.255.25464.45.255.25532,766
9364.46.0.0/1764.46.0.1 to 64.46.127.25464.46.127.25532,766
9464.46.128.0/1764.46.128.1 to 64.46.255.25464.46.255.25532,766
9564.47.0.0/1764.47.0.1 to 64.47.127.25464.47.127.25532,766
9664.47.128.0/1764.47.128.1 to 64.47.255.25464.47.255.25532,766
9764.48.0.0/1764.48.0.1 to 64.48.127.25464.48.127.25532,766
9864.48.128.0/1764.48.128.1 to 64.48.255.25464.48.255.25532,766
9964.49.0.0/1764.49.0.1 to 64.49.127.25464.49.127.25532,766
10064.49.128.0/1764.49.128.1 to 64.49.255.25464.49.255.25532,766
10164.50.0.0/1764.50.0.1 to 64.50.127.25464.50.127.25532,766
10264.50.128.0/1764.50.128.1 to 64.50.255.25464.50.255.25532,766
10364.51.0.0/1764.51.0.1 to 64.51.127.25464.51.127.25532,766
10464.51.128.0/1764.51.128.1 to 64.51.255.25464.51.255.25532,766
10564.52.0.0/1764.52.0.1 to 64.52.127.25464.52.127.25532,766
10664.52.128.0/1764.52.128.1 to 64.52.255.25464.52.255.25532,766
10764.53.0.0/1764.53.0.1 to 64.53.127.25464.53.127.25532,766
10864.53.128.0/1764.53.128.1 to 64.53.255.25464.53.255.25532,766
10964.54.0.0/1764.54.0.1 to 64.54.127.25464.54.127.25532,766
11064.54.128.0/1764.54.128.1 to 64.54.255.25464.54.255.25532,766
11164.55.0.0/1764.55.0.1 to 64.55.127.25464.55.127.25532,766
11264.55.128.0/1764.55.128.1 to 64.55.255.25464.55.255.25532,766
11364.56.0.0/1764.56.0.1 to 64.56.127.25464.56.127.25532,766
11464.56.128.0/1764.56.128.1 to 64.56.255.25464.56.255.25532,766
11564.57.0.0/1764.57.0.1 to 64.57.127.25464.57.127.25532,766
11664.57.128.0/1764.57.128.1 to 64.57.255.25464.57.255.25532,766
11764.58.0.0/1764.58.0.1 to 64.58.127.25464.58.127.25532,766
11864.58.128.0/1764.58.128.1 to 64.58.255.25464.58.255.25532,766
11964.59.0.0/1764.59.0.1 to 64.59.127.25464.59.127.25532,766
12064.59.128.0/1764.59.128.1 to 64.59.255.25464.59.255.25532,766
12164.60.0.0/1764.60.0.1 to 64.60.127.25464.60.127.25532,766
12264.60.128.0/1764.60.128.1 to 64.60.255.25464.60.255.25532,766
12364.61.0.0/1764.61.0.1 to 64.61.127.25464.61.127.25532,766
12464.61.128.0/1764.61.128.1 to 64.61.255.25464.61.255.25532,766
12564.62.0.0/1764.62.0.1 to 64.62.127.25464.62.127.25532,766
12664.62.128.0/1764.62.128.1 to 64.62.255.25464.62.255.25532,766
12764.63.0.0/1764.63.0.1 to 64.63.127.25464.63.127.25532,766
12864.63.128.0/1764.63.128.1 to 64.63.255.25464.63.255.25532,766
12964.64.0.0/1764.64.0.1 to 64.64.127.25464.64.127.25532,766
13064.64.128.0/1764.64.128.1 to 64.64.255.25464.64.255.25532,766
13164.65.0.0/1764.65.0.1 to 64.65.127.25464.65.127.25532,766
13264.65.128.0/1764.65.128.1 to 64.65.255.25464.65.255.25532,766
13364.66.0.0/1764.66.0.1 to 64.66.127.25464.66.127.25532,766
13464.66.128.0/1764.66.128.1 to 64.66.255.25464.66.255.25532,766
13564.67.0.0/1764.67.0.1 to 64.67.127.25464.67.127.25532,766
13664.67.128.0/1764.67.128.1 to 64.67.255.25464.67.255.25532,766
13764.68.0.0/1764.68.0.1 to 64.68.127.25464.68.127.25532,766
13864.68.128.0/1764.68.128.1 to 64.68.255.25464.68.255.25532,766
13964.69.0.0/1764.69.0.1 to 64.69.127.25464.69.127.25532,766
14064.69.128.0/1764.69.128.1 to 64.69.255.25464.69.255.25532,766
14164.70.0.0/1764.70.0.1 to 64.70.127.25464.70.127.25532,766
14264.70.128.0/1764.70.128.1 to 64.70.255.25464.70.255.25532,766
14364.71.0.0/1764.71.0.1 to 64.71.127.25464.71.127.25532,766
14464.71.128.0/1764.71.128.1 to 64.71.255.25464.71.255.25532,766
14564.72.0.0/1764.72.0.1 to 64.72.127.25464.72.127.25532,766
14664.72.128.0/1764.72.128.1 to 64.72.255.25464.72.255.25532,766
14764.73.0.0/1764.73.0.1 to 64.73.127.25464.73.127.25532,766
14864.73.128.0/1764.73.128.1 to 64.73.255.25464.73.255.25532,766
14964.74.0.0/1764.74.0.1 to 64.74.127.25464.74.127.25532,766
15064.74.128.0/1764.74.128.1 to 64.74.255.25464.74.255.25532,766
15164.75.0.0/1764.75.0.1 to 64.75.127.25464.75.127.25532,766
15264.75.128.0/1764.75.128.1 to 64.75.255.25464.75.255.25532,766
15364.76.0.0/1764.76.0.1 to 64.76.127.25464.76.127.25532,766
15464.76.128.0/1764.76.128.1 to 64.76.255.25464.76.255.25532,766
15564.77.0.0/1764.77.0.1 to 64.77.127.25464.77.127.25532,766
15664.77.128.0/1764.77.128.1 to 64.77.255.25464.77.255.25532,766
15764.78.0.0/1764.78.0.1 to 64.78.127.25464.78.127.25532,766
15864.78.128.0/1764.78.128.1 to 64.78.255.25464.78.255.25532,766
15964.79.0.0/1764.79.0.1 to 64.79.127.25464.79.127.25532,766
16064.79.128.0/1764.79.128.1 to 64.79.255.25464.79.255.25532,766
16164.80.0.0/1764.80.0.1 to 64.80.127.25464.80.127.25532,766
16264.80.128.0/1764.80.128.1 to 64.80.255.25464.80.255.25532,766
16364.81.0.0/1764.81.0.1 to 64.81.127.25464.81.127.25532,766
16464.81.128.0/1764.81.128.1 to 64.81.255.25464.81.255.25532,766
16564.82.0.0/1764.82.0.1 to 64.82.127.25464.82.127.25532,766
16664.82.128.0/1764.82.128.1 to 64.82.255.25464.82.255.25532,766
16764.83.0.0/1764.83.0.1 to 64.83.127.25464.83.127.25532,766
16864.83.128.0/1764.83.128.1 to 64.83.255.25464.83.255.25532,766
16964.84.0.0/1764.84.0.1 to 64.84.127.25464.84.127.25532,766
17064.84.128.0/1764.84.128.1 to 64.84.255.25464.84.255.25532,766
17164.85.0.0/1764.85.0.1 to 64.85.127.25464.85.127.25532,766
17264.85.128.0/1764.85.128.1 to 64.85.255.25464.85.255.25532,766
17364.86.0.0/1764.86.0.1 to 64.86.127.25464.86.127.25532,766
17464.86.128.0/1764.86.128.1 to 64.86.255.25464.86.255.25532,766
17564.87.0.0/1764.87.0.1 to 64.87.127.25464.87.127.25532,766
17664.87.128.0/1764.87.128.1 to 64.87.255.25464.87.255.25532,766
17764.88.0.0/1764.88.0.1 to 64.88.127.25464.88.127.25532,766
17864.88.128.0/1764.88.128.1 to 64.88.255.25464.88.255.25532,766
17964.89.0.0/1764.89.0.1 to 64.89.127.25464.89.127.25532,766
18064.89.128.0/1764.89.128.1 to 64.89.255.25464.89.255.25532,766
18164.90.0.0/1764.90.0.1 to 64.90.127.25464.90.127.25532,766
18264.90.128.0/1764.90.128.1 to 64.90.255.25464.90.255.25532,766
18364.91.0.0/1764.91.0.1 to 64.91.127.25464.91.127.25532,766
18464.91.128.0/1764.91.128.1 to 64.91.255.25464.91.255.25532,766
18564.92.0.0/1764.92.0.1 to 64.92.127.25464.92.127.25532,766
18664.92.128.0/1764.92.128.1 to 64.92.255.25464.92.255.25532,766
18764.93.0.0/1764.93.0.1 to 64.93.127.25464.93.127.25532,766
18864.93.128.0/1764.93.128.1 to 64.93.255.25464.93.255.25532,766
18964.94.0.0/1764.94.0.1 to 64.94.127.25464.94.127.25532,766
19064.94.128.0/1764.94.128.1 to 64.94.255.25464.94.255.25532,766
19164.95.0.0/1764.95.0.1 to 64.95.127.25464.95.127.25532,766
19264.95.128.0/1764.95.128.1 to 64.95.255.25464.95.255.25532,766
19364.96.0.0/1764.96.0.1 to 64.96.127.25464.96.127.25532,766
19464.96.128.0/1764.96.128.1 to 64.96.255.25464.96.255.25532,766
19564.97.0.0/1764.97.0.1 to 64.97.127.25464.97.127.25532,766
19664.97.128.0/1764.97.128.1 to 64.97.255.25464.97.255.25532,766
19764.98.0.0/1764.98.0.1 to 64.98.127.25464.98.127.25532,766
19864.98.128.0/1764.98.128.1 to 64.98.255.25464.98.255.25532,766
19964.99.0.0/1764.99.0.1 to 64.99.127.25464.99.127.25532,766
20064.99.128.0/1764.99.128.1 to 64.99.255.25464.99.255.25532,766
20164.100.0.0/1764.100.0.1 to 64.100.127.25464.100.127.25532,766
20264.100.128.0/1764.100.128.1 to 64.100.255.25464.100.255.25532,766
20364.101.0.0/1764.101.0.1 to 64.101.127.25464.101.127.25532,766
20464.101.128.0/1764.101.128.1 to 64.101.255.25464.101.255.25532,766
20564.102.0.0/1764.102.0.1 to 64.102.127.25464.102.127.25532,766
20664.102.128.0/1764.102.128.1 to 64.102.255.25464.102.255.25532,766
20764.103.0.0/1764.103.0.1 to 64.103.127.25464.103.127.25532,766
20864.103.128.0/1764.103.128.1 to 64.103.255.25464.103.255.25532,766
20964.104.0.0/1764.104.0.1 to 64.104.127.25464.104.127.25532,766
21064.104.128.0/1764.104.128.1 to 64.104.255.25464.104.255.25532,766
21164.105.0.0/1764.105.0.1 to 64.105.127.25464.105.127.25532,766
21264.105.128.0/1764.105.128.1 to 64.105.255.25464.105.255.25532,766
21364.106.0.0/1764.106.0.1 to 64.106.127.25464.106.127.25532,766
21464.106.128.0/1764.106.128.1 to 64.106.255.25464.106.255.25532,766
21564.107.0.0/1764.107.0.1 to 64.107.127.25464.107.127.25532,766
21664.107.128.0/1764.107.128.1 to 64.107.255.25464.107.255.25532,766
21764.108.0.0/1764.108.0.1 to 64.108.127.25464.108.127.25532,766
21864.108.128.0/1764.108.128.1 to 64.108.255.25464.108.255.25532,766
21964.109.0.0/1764.109.0.1 to 64.109.127.25464.109.127.25532,766
22064.109.128.0/1764.109.128.1 to 64.109.255.25464.109.255.25532,766
22164.110.0.0/1764.110.0.1 to 64.110.127.25464.110.127.25532,766
22264.110.128.0/1764.110.128.1 to 64.110.255.25464.110.255.25532,766
22364.111.0.0/1764.111.0.1 to 64.111.127.25464.111.127.25532,766
22464.111.128.0/1764.111.128.1 to 64.111.255.25464.111.255.25532,766
22564.112.0.0/1764.112.0.1 to 64.112.127.25464.112.127.25532,766
22664.112.128.0/1764.112.128.1 to 64.112.255.25464.112.255.25532,766
22764.113.0.0/1764.113.0.1 to 64.113.127.25464.113.127.25532,766
22864.113.128.0/1764.113.128.1 to 64.113.255.25464.113.255.25532,766
22964.114.0.0/1764.114.0.1 to 64.114.127.25464.114.127.25532,766
23064.114.128.0/1764.114.128.1 to 64.114.255.25464.114.255.25532,766
23164.115.0.0/1764.115.0.1 to 64.115.127.25464.115.127.25532,766
23264.115.128.0/1764.115.128.1 to 64.115.255.25464.115.255.25532,766
23364.116.0.0/1764.116.0.1 to 64.116.127.25464.116.127.25532,766
23464.116.128.0/1764.116.128.1 to 64.116.255.25464.116.255.25532,766
23564.117.0.0/1764.117.0.1 to 64.117.127.25464.117.127.25532,766
23664.117.128.0/1764.117.128.1 to 64.117.255.25464.117.255.25532,766
23764.118.0.0/1764.118.0.1 to 64.118.127.25464.118.127.25532,766
23864.118.128.0/1764.118.128.1 to 64.118.255.25464.118.255.25532,766
23964.119.0.0/1764.119.0.1 to 64.119.127.25464.119.127.25532,766
24064.119.128.0/1764.119.128.1 to 64.119.255.25464.119.255.25532,766
24164.120.0.0/1764.120.0.1 to 64.120.127.25464.120.127.25532,766
24264.120.128.0/1764.120.128.1 to 64.120.255.25464.120.255.25532,766
24364.121.0.0/1764.121.0.1 to 64.121.127.25464.121.127.25532,766
24464.121.128.0/1764.121.128.1 to 64.121.255.25464.121.255.25532,766
24564.122.0.0/1764.122.0.1 to 64.122.127.25464.122.127.25532,766
24664.122.128.0/1764.122.128.1 to 64.122.255.25464.122.255.25532,766
24764.123.0.0/1764.123.0.1 to 64.123.127.25464.123.127.25532,766
24864.123.128.0/1764.123.128.1 to 64.123.255.25464.123.255.25532,766
24964.124.0.0/1764.124.0.1 to 64.124.127.25464.124.127.25532,766
25064.124.128.0/1764.124.128.1 to 64.124.255.25464.124.255.25532,766
25164.125.0.0/1764.125.0.1 to 64.125.127.25464.125.127.25532,766
25264.125.128.0/1764.125.128.1 to 64.125.255.25464.125.255.25532,766
25364.126.0.0/1764.126.0.1 to 64.126.127.25464.126.127.25532,766
25464.126.128.0/1764.126.128.1 to 64.126.255.25464.126.255.25532,766
25564.127.0.0/1764.127.0.1 to 64.127.127.25464.127.127.25532,766
25664.127.128.0/1764.127.128.1 to 64.127.255.25464.127.255.25532,766

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.