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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.

Network25.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
25.0.0.0
Broadcast address
25.127.255.255
First usable
25.0.0.1
Last usable
25.127.255.254
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 19000000 · Integer 419430400 to 427819007
Reverse DNS zones
0.25.in-addr.arpa
1.25.in-addr.arpa
2.25.in-addr.arpa
3.25.in-addr.arpa
4.25.in-addr.arpa
5.25.in-addr.arpa
6.25.in-addr.arpa
7.25.in-addr.arpa
8.25.in-addr.arpa
9.25.in-addr.arpa
10.25.in-addr.arpa
11.25.in-addr.arpa
12.25.in-addr.arpa
13.25.in-addr.arpa
14.25.in-addr.arpa
15.25.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
Address00011001.00000000.00000000.0000000025.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00011001.00000000.00000000.0000000025.0.0.0
Broadcast00011001.01111111.11111111.1111111125.127.255.255
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)

25.0.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.0.0.0/1725.0.0.1 to 25.0.127.25425.0.127.25532,766
225.0.128.0/1725.0.128.1 to 25.0.255.25425.0.255.25532,766
325.1.0.0/1725.1.0.1 to 25.1.127.25425.1.127.25532,766
425.1.128.0/1725.1.128.1 to 25.1.255.25425.1.255.25532,766
525.2.0.0/1725.2.0.1 to 25.2.127.25425.2.127.25532,766
625.2.128.0/1725.2.128.1 to 25.2.255.25425.2.255.25532,766
725.3.0.0/1725.3.0.1 to 25.3.127.25425.3.127.25532,766
825.3.128.0/1725.3.128.1 to 25.3.255.25425.3.255.25532,766
925.4.0.0/1725.4.0.1 to 25.4.127.25425.4.127.25532,766
1025.4.128.0/1725.4.128.1 to 25.4.255.25425.4.255.25532,766
1125.5.0.0/1725.5.0.1 to 25.5.127.25425.5.127.25532,766
1225.5.128.0/1725.5.128.1 to 25.5.255.25425.5.255.25532,766
1325.6.0.0/1725.6.0.1 to 25.6.127.25425.6.127.25532,766
1425.6.128.0/1725.6.128.1 to 25.6.255.25425.6.255.25532,766
1525.7.0.0/1725.7.0.1 to 25.7.127.25425.7.127.25532,766
1625.7.128.0/1725.7.128.1 to 25.7.255.25425.7.255.25532,766
1725.8.0.0/1725.8.0.1 to 25.8.127.25425.8.127.25532,766
1825.8.128.0/1725.8.128.1 to 25.8.255.25425.8.255.25532,766
1925.9.0.0/1725.9.0.1 to 25.9.127.25425.9.127.25532,766
2025.9.128.0/1725.9.128.1 to 25.9.255.25425.9.255.25532,766
2125.10.0.0/1725.10.0.1 to 25.10.127.25425.10.127.25532,766
2225.10.128.0/1725.10.128.1 to 25.10.255.25425.10.255.25532,766
2325.11.0.0/1725.11.0.1 to 25.11.127.25425.11.127.25532,766
2425.11.128.0/1725.11.128.1 to 25.11.255.25425.11.255.25532,766
2525.12.0.0/1725.12.0.1 to 25.12.127.25425.12.127.25532,766
2625.12.128.0/1725.12.128.1 to 25.12.255.25425.12.255.25532,766
2725.13.0.0/1725.13.0.1 to 25.13.127.25425.13.127.25532,766
2825.13.128.0/1725.13.128.1 to 25.13.255.25425.13.255.25532,766
2925.14.0.0/1725.14.0.1 to 25.14.127.25425.14.127.25532,766
3025.14.128.0/1725.14.128.1 to 25.14.255.25425.14.255.25532,766
3125.15.0.0/1725.15.0.1 to 25.15.127.25425.15.127.25532,766
3225.15.128.0/1725.15.128.1 to 25.15.255.25425.15.255.25532,766
3325.16.0.0/1725.16.0.1 to 25.16.127.25425.16.127.25532,766
3425.16.128.0/1725.16.128.1 to 25.16.255.25425.16.255.25532,766
3525.17.0.0/1725.17.0.1 to 25.17.127.25425.17.127.25532,766
3625.17.128.0/1725.17.128.1 to 25.17.255.25425.17.255.25532,766
3725.18.0.0/1725.18.0.1 to 25.18.127.25425.18.127.25532,766
3825.18.128.0/1725.18.128.1 to 25.18.255.25425.18.255.25532,766
3925.19.0.0/1725.19.0.1 to 25.19.127.25425.19.127.25532,766
4025.19.128.0/1725.19.128.1 to 25.19.255.25425.19.255.25532,766
4125.20.0.0/1725.20.0.1 to 25.20.127.25425.20.127.25532,766
4225.20.128.0/1725.20.128.1 to 25.20.255.25425.20.255.25532,766
4325.21.0.0/1725.21.0.1 to 25.21.127.25425.21.127.25532,766
4425.21.128.0/1725.21.128.1 to 25.21.255.25425.21.255.25532,766
4525.22.0.0/1725.22.0.1 to 25.22.127.25425.22.127.25532,766
4625.22.128.0/1725.22.128.1 to 25.22.255.25425.22.255.25532,766
4725.23.0.0/1725.23.0.1 to 25.23.127.25425.23.127.25532,766
4825.23.128.0/1725.23.128.1 to 25.23.255.25425.23.255.25532,766
4925.24.0.0/1725.24.0.1 to 25.24.127.25425.24.127.25532,766
5025.24.128.0/1725.24.128.1 to 25.24.255.25425.24.255.25532,766
5125.25.0.0/1725.25.0.1 to 25.25.127.25425.25.127.25532,766
5225.25.128.0/1725.25.128.1 to 25.25.255.25425.25.255.25532,766
5325.26.0.0/1725.26.0.1 to 25.26.127.25425.26.127.25532,766
5425.26.128.0/1725.26.128.1 to 25.26.255.25425.26.255.25532,766
5525.27.0.0/1725.27.0.1 to 25.27.127.25425.27.127.25532,766
5625.27.128.0/1725.27.128.1 to 25.27.255.25425.27.255.25532,766
5725.28.0.0/1725.28.0.1 to 25.28.127.25425.28.127.25532,766
5825.28.128.0/1725.28.128.1 to 25.28.255.25425.28.255.25532,766
5925.29.0.0/1725.29.0.1 to 25.29.127.25425.29.127.25532,766
6025.29.128.0/1725.29.128.1 to 25.29.255.25425.29.255.25532,766
6125.30.0.0/1725.30.0.1 to 25.30.127.25425.30.127.25532,766
6225.30.128.0/1725.30.128.1 to 25.30.255.25425.30.255.25532,766
6325.31.0.0/1725.31.0.1 to 25.31.127.25425.31.127.25532,766
6425.31.128.0/1725.31.128.1 to 25.31.255.25425.31.255.25532,766
6525.32.0.0/1725.32.0.1 to 25.32.127.25425.32.127.25532,766
6625.32.128.0/1725.32.128.1 to 25.32.255.25425.32.255.25532,766
6725.33.0.0/1725.33.0.1 to 25.33.127.25425.33.127.25532,766
6825.33.128.0/1725.33.128.1 to 25.33.255.25425.33.255.25532,766
6925.34.0.0/1725.34.0.1 to 25.34.127.25425.34.127.25532,766
7025.34.128.0/1725.34.128.1 to 25.34.255.25425.34.255.25532,766
7125.35.0.0/1725.35.0.1 to 25.35.127.25425.35.127.25532,766
7225.35.128.0/1725.35.128.1 to 25.35.255.25425.35.255.25532,766
7325.36.0.0/1725.36.0.1 to 25.36.127.25425.36.127.25532,766
7425.36.128.0/1725.36.128.1 to 25.36.255.25425.36.255.25532,766
7525.37.0.0/1725.37.0.1 to 25.37.127.25425.37.127.25532,766
7625.37.128.0/1725.37.128.1 to 25.37.255.25425.37.255.25532,766
7725.38.0.0/1725.38.0.1 to 25.38.127.25425.38.127.25532,766
7825.38.128.0/1725.38.128.1 to 25.38.255.25425.38.255.25532,766
7925.39.0.0/1725.39.0.1 to 25.39.127.25425.39.127.25532,766
8025.39.128.0/1725.39.128.1 to 25.39.255.25425.39.255.25532,766
8125.40.0.0/1725.40.0.1 to 25.40.127.25425.40.127.25532,766
8225.40.128.0/1725.40.128.1 to 25.40.255.25425.40.255.25532,766
8325.41.0.0/1725.41.0.1 to 25.41.127.25425.41.127.25532,766
8425.41.128.0/1725.41.128.1 to 25.41.255.25425.41.255.25532,766
8525.42.0.0/1725.42.0.1 to 25.42.127.25425.42.127.25532,766
8625.42.128.0/1725.42.128.1 to 25.42.255.25425.42.255.25532,766
8725.43.0.0/1725.43.0.1 to 25.43.127.25425.43.127.25532,766
8825.43.128.0/1725.43.128.1 to 25.43.255.25425.43.255.25532,766
8925.44.0.0/1725.44.0.1 to 25.44.127.25425.44.127.25532,766
9025.44.128.0/1725.44.128.1 to 25.44.255.25425.44.255.25532,766
9125.45.0.0/1725.45.0.1 to 25.45.127.25425.45.127.25532,766
9225.45.128.0/1725.45.128.1 to 25.45.255.25425.45.255.25532,766
9325.46.0.0/1725.46.0.1 to 25.46.127.25425.46.127.25532,766
9425.46.128.0/1725.46.128.1 to 25.46.255.25425.46.255.25532,766
9525.47.0.0/1725.47.0.1 to 25.47.127.25425.47.127.25532,766
9625.47.128.0/1725.47.128.1 to 25.47.255.25425.47.255.25532,766
9725.48.0.0/1725.48.0.1 to 25.48.127.25425.48.127.25532,766
9825.48.128.0/1725.48.128.1 to 25.48.255.25425.48.255.25532,766
9925.49.0.0/1725.49.0.1 to 25.49.127.25425.49.127.25532,766
10025.49.128.0/1725.49.128.1 to 25.49.255.25425.49.255.25532,766
10125.50.0.0/1725.50.0.1 to 25.50.127.25425.50.127.25532,766
10225.50.128.0/1725.50.128.1 to 25.50.255.25425.50.255.25532,766
10325.51.0.0/1725.51.0.1 to 25.51.127.25425.51.127.25532,766
10425.51.128.0/1725.51.128.1 to 25.51.255.25425.51.255.25532,766
10525.52.0.0/1725.52.0.1 to 25.52.127.25425.52.127.25532,766
10625.52.128.0/1725.52.128.1 to 25.52.255.25425.52.255.25532,766
10725.53.0.0/1725.53.0.1 to 25.53.127.25425.53.127.25532,766
10825.53.128.0/1725.53.128.1 to 25.53.255.25425.53.255.25532,766
10925.54.0.0/1725.54.0.1 to 25.54.127.25425.54.127.25532,766
11025.54.128.0/1725.54.128.1 to 25.54.255.25425.54.255.25532,766
11125.55.0.0/1725.55.0.1 to 25.55.127.25425.55.127.25532,766
11225.55.128.0/1725.55.128.1 to 25.55.255.25425.55.255.25532,766
11325.56.0.0/1725.56.0.1 to 25.56.127.25425.56.127.25532,766
11425.56.128.0/1725.56.128.1 to 25.56.255.25425.56.255.25532,766
11525.57.0.0/1725.57.0.1 to 25.57.127.25425.57.127.25532,766
11625.57.128.0/1725.57.128.1 to 25.57.255.25425.57.255.25532,766
11725.58.0.0/1725.58.0.1 to 25.58.127.25425.58.127.25532,766
11825.58.128.0/1725.58.128.1 to 25.58.255.25425.58.255.25532,766
11925.59.0.0/1725.59.0.1 to 25.59.127.25425.59.127.25532,766
12025.59.128.0/1725.59.128.1 to 25.59.255.25425.59.255.25532,766
12125.60.0.0/1725.60.0.1 to 25.60.127.25425.60.127.25532,766
12225.60.128.0/1725.60.128.1 to 25.60.255.25425.60.255.25532,766
12325.61.0.0/1725.61.0.1 to 25.61.127.25425.61.127.25532,766
12425.61.128.0/1725.61.128.1 to 25.61.255.25425.61.255.25532,766
12525.62.0.0/1725.62.0.1 to 25.62.127.25425.62.127.25532,766
12625.62.128.0/1725.62.128.1 to 25.62.255.25425.62.255.25532,766
12725.63.0.0/1725.63.0.1 to 25.63.127.25425.63.127.25532,766
12825.63.128.0/1725.63.128.1 to 25.63.255.25425.63.255.25532,766
12925.64.0.0/1725.64.0.1 to 25.64.127.25425.64.127.25532,766
13025.64.128.0/1725.64.128.1 to 25.64.255.25425.64.255.25532,766
13125.65.0.0/1725.65.0.1 to 25.65.127.25425.65.127.25532,766
13225.65.128.0/1725.65.128.1 to 25.65.255.25425.65.255.25532,766
13325.66.0.0/1725.66.0.1 to 25.66.127.25425.66.127.25532,766
13425.66.128.0/1725.66.128.1 to 25.66.255.25425.66.255.25532,766
13525.67.0.0/1725.67.0.1 to 25.67.127.25425.67.127.25532,766
13625.67.128.0/1725.67.128.1 to 25.67.255.25425.67.255.25532,766
13725.68.0.0/1725.68.0.1 to 25.68.127.25425.68.127.25532,766
13825.68.128.0/1725.68.128.1 to 25.68.255.25425.68.255.25532,766
13925.69.0.0/1725.69.0.1 to 25.69.127.25425.69.127.25532,766
14025.69.128.0/1725.69.128.1 to 25.69.255.25425.69.255.25532,766
14125.70.0.0/1725.70.0.1 to 25.70.127.25425.70.127.25532,766
14225.70.128.0/1725.70.128.1 to 25.70.255.25425.70.255.25532,766
14325.71.0.0/1725.71.0.1 to 25.71.127.25425.71.127.25532,766
14425.71.128.0/1725.71.128.1 to 25.71.255.25425.71.255.25532,766
14525.72.0.0/1725.72.0.1 to 25.72.127.25425.72.127.25532,766
14625.72.128.0/1725.72.128.1 to 25.72.255.25425.72.255.25532,766
14725.73.0.0/1725.73.0.1 to 25.73.127.25425.73.127.25532,766
14825.73.128.0/1725.73.128.1 to 25.73.255.25425.73.255.25532,766
14925.74.0.0/1725.74.0.1 to 25.74.127.25425.74.127.25532,766
15025.74.128.0/1725.74.128.1 to 25.74.255.25425.74.255.25532,766
15125.75.0.0/1725.75.0.1 to 25.75.127.25425.75.127.25532,766
15225.75.128.0/1725.75.128.1 to 25.75.255.25425.75.255.25532,766
15325.76.0.0/1725.76.0.1 to 25.76.127.25425.76.127.25532,766
15425.76.128.0/1725.76.128.1 to 25.76.255.25425.76.255.25532,766
15525.77.0.0/1725.77.0.1 to 25.77.127.25425.77.127.25532,766
15625.77.128.0/1725.77.128.1 to 25.77.255.25425.77.255.25532,766
15725.78.0.0/1725.78.0.1 to 25.78.127.25425.78.127.25532,766
15825.78.128.0/1725.78.128.1 to 25.78.255.25425.78.255.25532,766
15925.79.0.0/1725.79.0.1 to 25.79.127.25425.79.127.25532,766
16025.79.128.0/1725.79.128.1 to 25.79.255.25425.79.255.25532,766
16125.80.0.0/1725.80.0.1 to 25.80.127.25425.80.127.25532,766
16225.80.128.0/1725.80.128.1 to 25.80.255.25425.80.255.25532,766
16325.81.0.0/1725.81.0.1 to 25.81.127.25425.81.127.25532,766
16425.81.128.0/1725.81.128.1 to 25.81.255.25425.81.255.25532,766
16525.82.0.0/1725.82.0.1 to 25.82.127.25425.82.127.25532,766
16625.82.128.0/1725.82.128.1 to 25.82.255.25425.82.255.25532,766
16725.83.0.0/1725.83.0.1 to 25.83.127.25425.83.127.25532,766
16825.83.128.0/1725.83.128.1 to 25.83.255.25425.83.255.25532,766
16925.84.0.0/1725.84.0.1 to 25.84.127.25425.84.127.25532,766
17025.84.128.0/1725.84.128.1 to 25.84.255.25425.84.255.25532,766
17125.85.0.0/1725.85.0.1 to 25.85.127.25425.85.127.25532,766
17225.85.128.0/1725.85.128.1 to 25.85.255.25425.85.255.25532,766
17325.86.0.0/1725.86.0.1 to 25.86.127.25425.86.127.25532,766
17425.86.128.0/1725.86.128.1 to 25.86.255.25425.86.255.25532,766
17525.87.0.0/1725.87.0.1 to 25.87.127.25425.87.127.25532,766
17625.87.128.0/1725.87.128.1 to 25.87.255.25425.87.255.25532,766
17725.88.0.0/1725.88.0.1 to 25.88.127.25425.88.127.25532,766
17825.88.128.0/1725.88.128.1 to 25.88.255.25425.88.255.25532,766
17925.89.0.0/1725.89.0.1 to 25.89.127.25425.89.127.25532,766
18025.89.128.0/1725.89.128.1 to 25.89.255.25425.89.255.25532,766
18125.90.0.0/1725.90.0.1 to 25.90.127.25425.90.127.25532,766
18225.90.128.0/1725.90.128.1 to 25.90.255.25425.90.255.25532,766
18325.91.0.0/1725.91.0.1 to 25.91.127.25425.91.127.25532,766
18425.91.128.0/1725.91.128.1 to 25.91.255.25425.91.255.25532,766
18525.92.0.0/1725.92.0.1 to 25.92.127.25425.92.127.25532,766
18625.92.128.0/1725.92.128.1 to 25.92.255.25425.92.255.25532,766
18725.93.0.0/1725.93.0.1 to 25.93.127.25425.93.127.25532,766
18825.93.128.0/1725.93.128.1 to 25.93.255.25425.93.255.25532,766
18925.94.0.0/1725.94.0.1 to 25.94.127.25425.94.127.25532,766
19025.94.128.0/1725.94.128.1 to 25.94.255.25425.94.255.25532,766
19125.95.0.0/1725.95.0.1 to 25.95.127.25425.95.127.25532,766
19225.95.128.0/1725.95.128.1 to 25.95.255.25425.95.255.25532,766
19325.96.0.0/1725.96.0.1 to 25.96.127.25425.96.127.25532,766
19425.96.128.0/1725.96.128.1 to 25.96.255.25425.96.255.25532,766
19525.97.0.0/1725.97.0.1 to 25.97.127.25425.97.127.25532,766
19625.97.128.0/1725.97.128.1 to 25.97.255.25425.97.255.25532,766
19725.98.0.0/1725.98.0.1 to 25.98.127.25425.98.127.25532,766
19825.98.128.0/1725.98.128.1 to 25.98.255.25425.98.255.25532,766
19925.99.0.0/1725.99.0.1 to 25.99.127.25425.99.127.25532,766
20025.99.128.0/1725.99.128.1 to 25.99.255.25425.99.255.25532,766
20125.100.0.0/1725.100.0.1 to 25.100.127.25425.100.127.25532,766
20225.100.128.0/1725.100.128.1 to 25.100.255.25425.100.255.25532,766
20325.101.0.0/1725.101.0.1 to 25.101.127.25425.101.127.25532,766
20425.101.128.0/1725.101.128.1 to 25.101.255.25425.101.255.25532,766
20525.102.0.0/1725.102.0.1 to 25.102.127.25425.102.127.25532,766
20625.102.128.0/1725.102.128.1 to 25.102.255.25425.102.255.25532,766
20725.103.0.0/1725.103.0.1 to 25.103.127.25425.103.127.25532,766
20825.103.128.0/1725.103.128.1 to 25.103.255.25425.103.255.25532,766
20925.104.0.0/1725.104.0.1 to 25.104.127.25425.104.127.25532,766
21025.104.128.0/1725.104.128.1 to 25.104.255.25425.104.255.25532,766
21125.105.0.0/1725.105.0.1 to 25.105.127.25425.105.127.25532,766
21225.105.128.0/1725.105.128.1 to 25.105.255.25425.105.255.25532,766
21325.106.0.0/1725.106.0.1 to 25.106.127.25425.106.127.25532,766
21425.106.128.0/1725.106.128.1 to 25.106.255.25425.106.255.25532,766
21525.107.0.0/1725.107.0.1 to 25.107.127.25425.107.127.25532,766
21625.107.128.0/1725.107.128.1 to 25.107.255.25425.107.255.25532,766
21725.108.0.0/1725.108.0.1 to 25.108.127.25425.108.127.25532,766
21825.108.128.0/1725.108.128.1 to 25.108.255.25425.108.255.25532,766
21925.109.0.0/1725.109.0.1 to 25.109.127.25425.109.127.25532,766
22025.109.128.0/1725.109.128.1 to 25.109.255.25425.109.255.25532,766
22125.110.0.0/1725.110.0.1 to 25.110.127.25425.110.127.25532,766
22225.110.128.0/1725.110.128.1 to 25.110.255.25425.110.255.25532,766
22325.111.0.0/1725.111.0.1 to 25.111.127.25425.111.127.25532,766
22425.111.128.0/1725.111.128.1 to 25.111.255.25425.111.255.25532,766
22525.112.0.0/1725.112.0.1 to 25.112.127.25425.112.127.25532,766
22625.112.128.0/1725.112.128.1 to 25.112.255.25425.112.255.25532,766
22725.113.0.0/1725.113.0.1 to 25.113.127.25425.113.127.25532,766
22825.113.128.0/1725.113.128.1 to 25.113.255.25425.113.255.25532,766
22925.114.0.0/1725.114.0.1 to 25.114.127.25425.114.127.25532,766
23025.114.128.0/1725.114.128.1 to 25.114.255.25425.114.255.25532,766
23125.115.0.0/1725.115.0.1 to 25.115.127.25425.115.127.25532,766
23225.115.128.0/1725.115.128.1 to 25.115.255.25425.115.255.25532,766
23325.116.0.0/1725.116.0.1 to 25.116.127.25425.116.127.25532,766
23425.116.128.0/1725.116.128.1 to 25.116.255.25425.116.255.25532,766
23525.117.0.0/1725.117.0.1 to 25.117.127.25425.117.127.25532,766
23625.117.128.0/1725.117.128.1 to 25.117.255.25425.117.255.25532,766
23725.118.0.0/1725.118.0.1 to 25.118.127.25425.118.127.25532,766
23825.118.128.0/1725.118.128.1 to 25.118.255.25425.118.255.25532,766
23925.119.0.0/1725.119.0.1 to 25.119.127.25425.119.127.25532,766
24025.119.128.0/1725.119.128.1 to 25.119.255.25425.119.255.25532,766
24125.120.0.0/1725.120.0.1 to 25.120.127.25425.120.127.25532,766
24225.120.128.0/1725.120.128.1 to 25.120.255.25425.120.255.25532,766
24325.121.0.0/1725.121.0.1 to 25.121.127.25425.121.127.25532,766
24425.121.128.0/1725.121.128.1 to 25.121.255.25425.121.255.25532,766
24525.122.0.0/1725.122.0.1 to 25.122.127.25425.122.127.25532,766
24625.122.128.0/1725.122.128.1 to 25.122.255.25425.122.255.25532,766
24725.123.0.0/1725.123.0.1 to 25.123.127.25425.123.127.25532,766
24825.123.128.0/1725.123.128.1 to 25.123.255.25425.123.255.25532,766
24925.124.0.0/1725.124.0.1 to 25.124.127.25425.124.127.25532,766
25025.124.128.0/1725.124.128.1 to 25.124.255.25425.124.255.25532,766
25125.125.0.0/1725.125.0.1 to 25.125.127.25425.125.127.25532,766
25225.125.128.0/1725.125.128.1 to 25.125.255.25425.125.255.25532,766
25325.126.0.0/1725.126.0.1 to 25.126.127.25425.126.127.25532,766
25425.126.128.0/1725.126.128.1 to 25.126.255.25425.126.255.25532,766
25525.127.0.0/1725.127.0.1 to 25.127.127.25425.127.127.25532,766
25625.127.128.0/1725.127.128.1 to 25.127.255.25425.127.255.25532,766

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.