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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.

Network17.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
17.0.0.0
Broadcast address
17.255.255.255
First usable
17.0.0.1
Last usable
17.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 11000000 · Integer 285212672 to 301989887
Reverse DNS zone
17.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010001..00000000.00000000.0000000017.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00010001..00000000.00000000.0000000017.0.0.0
Broadcast00010001..11111111.11111111.1111111117.255.255.255
Split into smaller subnets/17
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

17.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
117.0.0.0/1717.0.0.1 to 17.0.127.25417.0.127.25532,766
217.0.128.0/1717.0.128.1 to 17.0.255.25417.0.255.25532,766
317.1.0.0/1717.1.0.1 to 17.1.127.25417.1.127.25532,766
417.1.128.0/1717.1.128.1 to 17.1.255.25417.1.255.25532,766
517.2.0.0/1717.2.0.1 to 17.2.127.25417.2.127.25532,766
617.2.128.0/1717.2.128.1 to 17.2.255.25417.2.255.25532,766
717.3.0.0/1717.3.0.1 to 17.3.127.25417.3.127.25532,766
817.3.128.0/1717.3.128.1 to 17.3.255.25417.3.255.25532,766
917.4.0.0/1717.4.0.1 to 17.4.127.25417.4.127.25532,766
1017.4.128.0/1717.4.128.1 to 17.4.255.25417.4.255.25532,766
1117.5.0.0/1717.5.0.1 to 17.5.127.25417.5.127.25532,766
1217.5.128.0/1717.5.128.1 to 17.5.255.25417.5.255.25532,766
1317.6.0.0/1717.6.0.1 to 17.6.127.25417.6.127.25532,766
1417.6.128.0/1717.6.128.1 to 17.6.255.25417.6.255.25532,766
1517.7.0.0/1717.7.0.1 to 17.7.127.25417.7.127.25532,766
1617.7.128.0/1717.7.128.1 to 17.7.255.25417.7.255.25532,766
1717.8.0.0/1717.8.0.1 to 17.8.127.25417.8.127.25532,766
1817.8.128.0/1717.8.128.1 to 17.8.255.25417.8.255.25532,766
1917.9.0.0/1717.9.0.1 to 17.9.127.25417.9.127.25532,766
2017.9.128.0/1717.9.128.1 to 17.9.255.25417.9.255.25532,766
2117.10.0.0/1717.10.0.1 to 17.10.127.25417.10.127.25532,766
2217.10.128.0/1717.10.128.1 to 17.10.255.25417.10.255.25532,766
2317.11.0.0/1717.11.0.1 to 17.11.127.25417.11.127.25532,766
2417.11.128.0/1717.11.128.1 to 17.11.255.25417.11.255.25532,766
2517.12.0.0/1717.12.0.1 to 17.12.127.25417.12.127.25532,766
2617.12.128.0/1717.12.128.1 to 17.12.255.25417.12.255.25532,766
2717.13.0.0/1717.13.0.1 to 17.13.127.25417.13.127.25532,766
2817.13.128.0/1717.13.128.1 to 17.13.255.25417.13.255.25532,766
2917.14.0.0/1717.14.0.1 to 17.14.127.25417.14.127.25532,766
3017.14.128.0/1717.14.128.1 to 17.14.255.25417.14.255.25532,766
3117.15.0.0/1717.15.0.1 to 17.15.127.25417.15.127.25532,766
3217.15.128.0/1717.15.128.1 to 17.15.255.25417.15.255.25532,766
3317.16.0.0/1717.16.0.1 to 17.16.127.25417.16.127.25532,766
3417.16.128.0/1717.16.128.1 to 17.16.255.25417.16.255.25532,766
3517.17.0.0/1717.17.0.1 to 17.17.127.25417.17.127.25532,766
3617.17.128.0/1717.17.128.1 to 17.17.255.25417.17.255.25532,766
3717.18.0.0/1717.18.0.1 to 17.18.127.25417.18.127.25532,766
3817.18.128.0/1717.18.128.1 to 17.18.255.25417.18.255.25532,766
3917.19.0.0/1717.19.0.1 to 17.19.127.25417.19.127.25532,766
4017.19.128.0/1717.19.128.1 to 17.19.255.25417.19.255.25532,766
4117.20.0.0/1717.20.0.1 to 17.20.127.25417.20.127.25532,766
4217.20.128.0/1717.20.128.1 to 17.20.255.25417.20.255.25532,766
4317.21.0.0/1717.21.0.1 to 17.21.127.25417.21.127.25532,766
4417.21.128.0/1717.21.128.1 to 17.21.255.25417.21.255.25532,766
4517.22.0.0/1717.22.0.1 to 17.22.127.25417.22.127.25532,766
4617.22.128.0/1717.22.128.1 to 17.22.255.25417.22.255.25532,766
4717.23.0.0/1717.23.0.1 to 17.23.127.25417.23.127.25532,766
4817.23.128.0/1717.23.128.1 to 17.23.255.25417.23.255.25532,766
4917.24.0.0/1717.24.0.1 to 17.24.127.25417.24.127.25532,766
5017.24.128.0/1717.24.128.1 to 17.24.255.25417.24.255.25532,766
5117.25.0.0/1717.25.0.1 to 17.25.127.25417.25.127.25532,766
5217.25.128.0/1717.25.128.1 to 17.25.255.25417.25.255.25532,766
5317.26.0.0/1717.26.0.1 to 17.26.127.25417.26.127.25532,766
5417.26.128.0/1717.26.128.1 to 17.26.255.25417.26.255.25532,766
5517.27.0.0/1717.27.0.1 to 17.27.127.25417.27.127.25532,766
5617.27.128.0/1717.27.128.1 to 17.27.255.25417.27.255.25532,766
5717.28.0.0/1717.28.0.1 to 17.28.127.25417.28.127.25532,766
5817.28.128.0/1717.28.128.1 to 17.28.255.25417.28.255.25532,766
5917.29.0.0/1717.29.0.1 to 17.29.127.25417.29.127.25532,766
6017.29.128.0/1717.29.128.1 to 17.29.255.25417.29.255.25532,766
6117.30.0.0/1717.30.0.1 to 17.30.127.25417.30.127.25532,766
6217.30.128.0/1717.30.128.1 to 17.30.255.25417.30.255.25532,766
6317.31.0.0/1717.31.0.1 to 17.31.127.25417.31.127.25532,766
6417.31.128.0/1717.31.128.1 to 17.31.255.25417.31.255.25532,766
6517.32.0.0/1717.32.0.1 to 17.32.127.25417.32.127.25532,766
6617.32.128.0/1717.32.128.1 to 17.32.255.25417.32.255.25532,766
6717.33.0.0/1717.33.0.1 to 17.33.127.25417.33.127.25532,766
6817.33.128.0/1717.33.128.1 to 17.33.255.25417.33.255.25532,766
6917.34.0.0/1717.34.0.1 to 17.34.127.25417.34.127.25532,766
7017.34.128.0/1717.34.128.1 to 17.34.255.25417.34.255.25532,766
7117.35.0.0/1717.35.0.1 to 17.35.127.25417.35.127.25532,766
7217.35.128.0/1717.35.128.1 to 17.35.255.25417.35.255.25532,766
7317.36.0.0/1717.36.0.1 to 17.36.127.25417.36.127.25532,766
7417.36.128.0/1717.36.128.1 to 17.36.255.25417.36.255.25532,766
7517.37.0.0/1717.37.0.1 to 17.37.127.25417.37.127.25532,766
7617.37.128.0/1717.37.128.1 to 17.37.255.25417.37.255.25532,766
7717.38.0.0/1717.38.0.1 to 17.38.127.25417.38.127.25532,766
7817.38.128.0/1717.38.128.1 to 17.38.255.25417.38.255.25532,766
7917.39.0.0/1717.39.0.1 to 17.39.127.25417.39.127.25532,766
8017.39.128.0/1717.39.128.1 to 17.39.255.25417.39.255.25532,766
8117.40.0.0/1717.40.0.1 to 17.40.127.25417.40.127.25532,766
8217.40.128.0/1717.40.128.1 to 17.40.255.25417.40.255.25532,766
8317.41.0.0/1717.41.0.1 to 17.41.127.25417.41.127.25532,766
8417.41.128.0/1717.41.128.1 to 17.41.255.25417.41.255.25532,766
8517.42.0.0/1717.42.0.1 to 17.42.127.25417.42.127.25532,766
8617.42.128.0/1717.42.128.1 to 17.42.255.25417.42.255.25532,766
8717.43.0.0/1717.43.0.1 to 17.43.127.25417.43.127.25532,766
8817.43.128.0/1717.43.128.1 to 17.43.255.25417.43.255.25532,766
8917.44.0.0/1717.44.0.1 to 17.44.127.25417.44.127.25532,766
9017.44.128.0/1717.44.128.1 to 17.44.255.25417.44.255.25532,766
9117.45.0.0/1717.45.0.1 to 17.45.127.25417.45.127.25532,766
9217.45.128.0/1717.45.128.1 to 17.45.255.25417.45.255.25532,766
9317.46.0.0/1717.46.0.1 to 17.46.127.25417.46.127.25532,766
9417.46.128.0/1717.46.128.1 to 17.46.255.25417.46.255.25532,766
9517.47.0.0/1717.47.0.1 to 17.47.127.25417.47.127.25532,766
9617.47.128.0/1717.47.128.1 to 17.47.255.25417.47.255.25532,766
9717.48.0.0/1717.48.0.1 to 17.48.127.25417.48.127.25532,766
9817.48.128.0/1717.48.128.1 to 17.48.255.25417.48.255.25532,766
9917.49.0.0/1717.49.0.1 to 17.49.127.25417.49.127.25532,766
10017.49.128.0/1717.49.128.1 to 17.49.255.25417.49.255.25532,766
10117.50.0.0/1717.50.0.1 to 17.50.127.25417.50.127.25532,766
10217.50.128.0/1717.50.128.1 to 17.50.255.25417.50.255.25532,766
10317.51.0.0/1717.51.0.1 to 17.51.127.25417.51.127.25532,766
10417.51.128.0/1717.51.128.1 to 17.51.255.25417.51.255.25532,766
10517.52.0.0/1717.52.0.1 to 17.52.127.25417.52.127.25532,766
10617.52.128.0/1717.52.128.1 to 17.52.255.25417.52.255.25532,766
10717.53.0.0/1717.53.0.1 to 17.53.127.25417.53.127.25532,766
10817.53.128.0/1717.53.128.1 to 17.53.255.25417.53.255.25532,766
10917.54.0.0/1717.54.0.1 to 17.54.127.25417.54.127.25532,766
11017.54.128.0/1717.54.128.1 to 17.54.255.25417.54.255.25532,766
11117.55.0.0/1717.55.0.1 to 17.55.127.25417.55.127.25532,766
11217.55.128.0/1717.55.128.1 to 17.55.255.25417.55.255.25532,766
11317.56.0.0/1717.56.0.1 to 17.56.127.25417.56.127.25532,766
11417.56.128.0/1717.56.128.1 to 17.56.255.25417.56.255.25532,766
11517.57.0.0/1717.57.0.1 to 17.57.127.25417.57.127.25532,766
11617.57.128.0/1717.57.128.1 to 17.57.255.25417.57.255.25532,766
11717.58.0.0/1717.58.0.1 to 17.58.127.25417.58.127.25532,766
11817.58.128.0/1717.58.128.1 to 17.58.255.25417.58.255.25532,766
11917.59.0.0/1717.59.0.1 to 17.59.127.25417.59.127.25532,766
12017.59.128.0/1717.59.128.1 to 17.59.255.25417.59.255.25532,766
12117.60.0.0/1717.60.0.1 to 17.60.127.25417.60.127.25532,766
12217.60.128.0/1717.60.128.1 to 17.60.255.25417.60.255.25532,766
12317.61.0.0/1717.61.0.1 to 17.61.127.25417.61.127.25532,766
12417.61.128.0/1717.61.128.1 to 17.61.255.25417.61.255.25532,766
12517.62.0.0/1717.62.0.1 to 17.62.127.25417.62.127.25532,766
12617.62.128.0/1717.62.128.1 to 17.62.255.25417.62.255.25532,766
12717.63.0.0/1717.63.0.1 to 17.63.127.25417.63.127.25532,766
12817.63.128.0/1717.63.128.1 to 17.63.255.25417.63.255.25532,766
12917.64.0.0/1717.64.0.1 to 17.64.127.25417.64.127.25532,766
13017.64.128.0/1717.64.128.1 to 17.64.255.25417.64.255.25532,766
13117.65.0.0/1717.65.0.1 to 17.65.127.25417.65.127.25532,766
13217.65.128.0/1717.65.128.1 to 17.65.255.25417.65.255.25532,766
13317.66.0.0/1717.66.0.1 to 17.66.127.25417.66.127.25532,766
13417.66.128.0/1717.66.128.1 to 17.66.255.25417.66.255.25532,766
13517.67.0.0/1717.67.0.1 to 17.67.127.25417.67.127.25532,766
13617.67.128.0/1717.67.128.1 to 17.67.255.25417.67.255.25532,766
13717.68.0.0/1717.68.0.1 to 17.68.127.25417.68.127.25532,766
13817.68.128.0/1717.68.128.1 to 17.68.255.25417.68.255.25532,766
13917.69.0.0/1717.69.0.1 to 17.69.127.25417.69.127.25532,766
14017.69.128.0/1717.69.128.1 to 17.69.255.25417.69.255.25532,766
14117.70.0.0/1717.70.0.1 to 17.70.127.25417.70.127.25532,766
14217.70.128.0/1717.70.128.1 to 17.70.255.25417.70.255.25532,766
14317.71.0.0/1717.71.0.1 to 17.71.127.25417.71.127.25532,766
14417.71.128.0/1717.71.128.1 to 17.71.255.25417.71.255.25532,766
14517.72.0.0/1717.72.0.1 to 17.72.127.25417.72.127.25532,766
14617.72.128.0/1717.72.128.1 to 17.72.255.25417.72.255.25532,766
14717.73.0.0/1717.73.0.1 to 17.73.127.25417.73.127.25532,766
14817.73.128.0/1717.73.128.1 to 17.73.255.25417.73.255.25532,766
14917.74.0.0/1717.74.0.1 to 17.74.127.25417.74.127.25532,766
15017.74.128.0/1717.74.128.1 to 17.74.255.25417.74.255.25532,766
15117.75.0.0/1717.75.0.1 to 17.75.127.25417.75.127.25532,766
15217.75.128.0/1717.75.128.1 to 17.75.255.25417.75.255.25532,766
15317.76.0.0/1717.76.0.1 to 17.76.127.25417.76.127.25532,766
15417.76.128.0/1717.76.128.1 to 17.76.255.25417.76.255.25532,766
15517.77.0.0/1717.77.0.1 to 17.77.127.25417.77.127.25532,766
15617.77.128.0/1717.77.128.1 to 17.77.255.25417.77.255.25532,766
15717.78.0.0/1717.78.0.1 to 17.78.127.25417.78.127.25532,766
15817.78.128.0/1717.78.128.1 to 17.78.255.25417.78.255.25532,766
15917.79.0.0/1717.79.0.1 to 17.79.127.25417.79.127.25532,766
16017.79.128.0/1717.79.128.1 to 17.79.255.25417.79.255.25532,766
16117.80.0.0/1717.80.0.1 to 17.80.127.25417.80.127.25532,766
16217.80.128.0/1717.80.128.1 to 17.80.255.25417.80.255.25532,766
16317.81.0.0/1717.81.0.1 to 17.81.127.25417.81.127.25532,766
16417.81.128.0/1717.81.128.1 to 17.81.255.25417.81.255.25532,766
16517.82.0.0/1717.82.0.1 to 17.82.127.25417.82.127.25532,766
16617.82.128.0/1717.82.128.1 to 17.82.255.25417.82.255.25532,766
16717.83.0.0/1717.83.0.1 to 17.83.127.25417.83.127.25532,766
16817.83.128.0/1717.83.128.1 to 17.83.255.25417.83.255.25532,766
16917.84.0.0/1717.84.0.1 to 17.84.127.25417.84.127.25532,766
17017.84.128.0/1717.84.128.1 to 17.84.255.25417.84.255.25532,766
17117.85.0.0/1717.85.0.1 to 17.85.127.25417.85.127.25532,766
17217.85.128.0/1717.85.128.1 to 17.85.255.25417.85.255.25532,766
17317.86.0.0/1717.86.0.1 to 17.86.127.25417.86.127.25532,766
17417.86.128.0/1717.86.128.1 to 17.86.255.25417.86.255.25532,766
17517.87.0.0/1717.87.0.1 to 17.87.127.25417.87.127.25532,766
17617.87.128.0/1717.87.128.1 to 17.87.255.25417.87.255.25532,766
17717.88.0.0/1717.88.0.1 to 17.88.127.25417.88.127.25532,766
17817.88.128.0/1717.88.128.1 to 17.88.255.25417.88.255.25532,766
17917.89.0.0/1717.89.0.1 to 17.89.127.25417.89.127.25532,766
18017.89.128.0/1717.89.128.1 to 17.89.255.25417.89.255.25532,766
18117.90.0.0/1717.90.0.1 to 17.90.127.25417.90.127.25532,766
18217.90.128.0/1717.90.128.1 to 17.90.255.25417.90.255.25532,766
18317.91.0.0/1717.91.0.1 to 17.91.127.25417.91.127.25532,766
18417.91.128.0/1717.91.128.1 to 17.91.255.25417.91.255.25532,766
18517.92.0.0/1717.92.0.1 to 17.92.127.25417.92.127.25532,766
18617.92.128.0/1717.92.128.1 to 17.92.255.25417.92.255.25532,766
18717.93.0.0/1717.93.0.1 to 17.93.127.25417.93.127.25532,766
18817.93.128.0/1717.93.128.1 to 17.93.255.25417.93.255.25532,766
18917.94.0.0/1717.94.0.1 to 17.94.127.25417.94.127.25532,766
19017.94.128.0/1717.94.128.1 to 17.94.255.25417.94.255.25532,766
19117.95.0.0/1717.95.0.1 to 17.95.127.25417.95.127.25532,766
19217.95.128.0/1717.95.128.1 to 17.95.255.25417.95.255.25532,766
19317.96.0.0/1717.96.0.1 to 17.96.127.25417.96.127.25532,766
19417.96.128.0/1717.96.128.1 to 17.96.255.25417.96.255.25532,766
19517.97.0.0/1717.97.0.1 to 17.97.127.25417.97.127.25532,766
19617.97.128.0/1717.97.128.1 to 17.97.255.25417.97.255.25532,766
19717.98.0.0/1717.98.0.1 to 17.98.127.25417.98.127.25532,766
19817.98.128.0/1717.98.128.1 to 17.98.255.25417.98.255.25532,766
19917.99.0.0/1717.99.0.1 to 17.99.127.25417.99.127.25532,766
20017.99.128.0/1717.99.128.1 to 17.99.255.25417.99.255.25532,766
20117.100.0.0/1717.100.0.1 to 17.100.127.25417.100.127.25532,766
20217.100.128.0/1717.100.128.1 to 17.100.255.25417.100.255.25532,766
20317.101.0.0/1717.101.0.1 to 17.101.127.25417.101.127.25532,766
20417.101.128.0/1717.101.128.1 to 17.101.255.25417.101.255.25532,766
20517.102.0.0/1717.102.0.1 to 17.102.127.25417.102.127.25532,766
20617.102.128.0/1717.102.128.1 to 17.102.255.25417.102.255.25532,766
20717.103.0.0/1717.103.0.1 to 17.103.127.25417.103.127.25532,766
20817.103.128.0/1717.103.128.1 to 17.103.255.25417.103.255.25532,766
20917.104.0.0/1717.104.0.1 to 17.104.127.25417.104.127.25532,766
21017.104.128.0/1717.104.128.1 to 17.104.255.25417.104.255.25532,766
21117.105.0.0/1717.105.0.1 to 17.105.127.25417.105.127.25532,766
21217.105.128.0/1717.105.128.1 to 17.105.255.25417.105.255.25532,766
21317.106.0.0/1717.106.0.1 to 17.106.127.25417.106.127.25532,766
21417.106.128.0/1717.106.128.1 to 17.106.255.25417.106.255.25532,766
21517.107.0.0/1717.107.0.1 to 17.107.127.25417.107.127.25532,766
21617.107.128.0/1717.107.128.1 to 17.107.255.25417.107.255.25532,766
21717.108.0.0/1717.108.0.1 to 17.108.127.25417.108.127.25532,766
21817.108.128.0/1717.108.128.1 to 17.108.255.25417.108.255.25532,766
21917.109.0.0/1717.109.0.1 to 17.109.127.25417.109.127.25532,766
22017.109.128.0/1717.109.128.1 to 17.109.255.25417.109.255.25532,766
22117.110.0.0/1717.110.0.1 to 17.110.127.25417.110.127.25532,766
22217.110.128.0/1717.110.128.1 to 17.110.255.25417.110.255.25532,766
22317.111.0.0/1717.111.0.1 to 17.111.127.25417.111.127.25532,766
22417.111.128.0/1717.111.128.1 to 17.111.255.25417.111.255.25532,766
22517.112.0.0/1717.112.0.1 to 17.112.127.25417.112.127.25532,766
22617.112.128.0/1717.112.128.1 to 17.112.255.25417.112.255.25532,766
22717.113.0.0/1717.113.0.1 to 17.113.127.25417.113.127.25532,766
22817.113.128.0/1717.113.128.1 to 17.113.255.25417.113.255.25532,766
22917.114.0.0/1717.114.0.1 to 17.114.127.25417.114.127.25532,766
23017.114.128.0/1717.114.128.1 to 17.114.255.25417.114.255.25532,766
23117.115.0.0/1717.115.0.1 to 17.115.127.25417.115.127.25532,766
23217.115.128.0/1717.115.128.1 to 17.115.255.25417.115.255.25532,766
23317.116.0.0/1717.116.0.1 to 17.116.127.25417.116.127.25532,766
23417.116.128.0/1717.116.128.1 to 17.116.255.25417.116.255.25532,766
23517.117.0.0/1717.117.0.1 to 17.117.127.25417.117.127.25532,766
23617.117.128.0/1717.117.128.1 to 17.117.255.25417.117.255.25532,766
23717.118.0.0/1717.118.0.1 to 17.118.127.25417.118.127.25532,766
23817.118.128.0/1717.118.128.1 to 17.118.255.25417.118.255.25532,766
23917.119.0.0/1717.119.0.1 to 17.119.127.25417.119.127.25532,766
24017.119.128.0/1717.119.128.1 to 17.119.255.25417.119.255.25532,766
24117.120.0.0/1717.120.0.1 to 17.120.127.25417.120.127.25532,766
24217.120.128.0/1717.120.128.1 to 17.120.255.25417.120.255.25532,766
24317.121.0.0/1717.121.0.1 to 17.121.127.25417.121.127.25532,766
24417.121.128.0/1717.121.128.1 to 17.121.255.25417.121.255.25532,766
24517.122.0.0/1717.122.0.1 to 17.122.127.25417.122.127.25532,766
24617.122.128.0/1717.122.128.1 to 17.122.255.25417.122.255.25532,766
24717.123.0.0/1717.123.0.1 to 17.123.127.25417.123.127.25532,766
24817.123.128.0/1717.123.128.1 to 17.123.255.25417.123.255.25532,766
24917.124.0.0/1717.124.0.1 to 17.124.127.25417.124.127.25532,766
25017.124.128.0/1717.124.128.1 to 17.124.255.25417.124.255.25532,766
25117.125.0.0/1717.125.0.1 to 17.125.127.25417.125.127.25532,766
25217.125.128.0/1717.125.128.1 to 17.125.255.25417.125.255.25532,766
25317.126.0.0/1717.126.0.1 to 17.126.127.25417.126.127.25532,766
25417.126.128.0/1717.126.128.1 to 17.126.255.25417.126.255.25532,766
25517.127.0.0/1717.127.0.1 to 17.127.127.25417.127.127.25532,766
25617.127.128.0/1717.127.128.1 to 17.127.255.25417.127.255.25532,766

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.