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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.

Network81.201.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
81.201.0.0
Broadcast address
81.201.255.255
First usable
81.201.0.1
Last usable
81.201.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
A (default /8)
As numbers
Hex 51C90000 · Integer 1372127232 to 1372192767
Reverse DNS zone
201.81.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010001.11001001..00000000.0000000081.201.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network01010001.11001001..00000000.0000000081.201.0.0
Broadcast01010001.11001001..11111111.1111111181.201.255.255
Split into smaller subnets/25
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

81.201.0.0/16 makes 512 subnets of /25; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
181.201.0.0/2581.201.0.1 to 81.201.0.12681.201.0.127126
281.201.0.128/2581.201.0.129 to 81.201.0.25481.201.0.255126
381.201.1.0/2581.201.1.1 to 81.201.1.12681.201.1.127126
481.201.1.128/2581.201.1.129 to 81.201.1.25481.201.1.255126
581.201.2.0/2581.201.2.1 to 81.201.2.12681.201.2.127126
681.201.2.128/2581.201.2.129 to 81.201.2.25481.201.2.255126
781.201.3.0/2581.201.3.1 to 81.201.3.12681.201.3.127126
881.201.3.128/2581.201.3.129 to 81.201.3.25481.201.3.255126
981.201.4.0/2581.201.4.1 to 81.201.4.12681.201.4.127126
1081.201.4.128/2581.201.4.129 to 81.201.4.25481.201.4.255126
1181.201.5.0/2581.201.5.1 to 81.201.5.12681.201.5.127126
1281.201.5.128/2581.201.5.129 to 81.201.5.25481.201.5.255126
1381.201.6.0/2581.201.6.1 to 81.201.6.12681.201.6.127126
1481.201.6.128/2581.201.6.129 to 81.201.6.25481.201.6.255126
1581.201.7.0/2581.201.7.1 to 81.201.7.12681.201.7.127126
1681.201.7.128/2581.201.7.129 to 81.201.7.25481.201.7.255126
1781.201.8.0/2581.201.8.1 to 81.201.8.12681.201.8.127126
1881.201.8.128/2581.201.8.129 to 81.201.8.25481.201.8.255126
1981.201.9.0/2581.201.9.1 to 81.201.9.12681.201.9.127126
2081.201.9.128/2581.201.9.129 to 81.201.9.25481.201.9.255126
2181.201.10.0/2581.201.10.1 to 81.201.10.12681.201.10.127126
2281.201.10.128/2581.201.10.129 to 81.201.10.25481.201.10.255126
2381.201.11.0/2581.201.11.1 to 81.201.11.12681.201.11.127126
2481.201.11.128/2581.201.11.129 to 81.201.11.25481.201.11.255126
2581.201.12.0/2581.201.12.1 to 81.201.12.12681.201.12.127126
2681.201.12.128/2581.201.12.129 to 81.201.12.25481.201.12.255126
2781.201.13.0/2581.201.13.1 to 81.201.13.12681.201.13.127126
2881.201.13.128/2581.201.13.129 to 81.201.13.25481.201.13.255126
2981.201.14.0/2581.201.14.1 to 81.201.14.12681.201.14.127126
3081.201.14.128/2581.201.14.129 to 81.201.14.25481.201.14.255126
3181.201.15.0/2581.201.15.1 to 81.201.15.12681.201.15.127126
3281.201.15.128/2581.201.15.129 to 81.201.15.25481.201.15.255126
3381.201.16.0/2581.201.16.1 to 81.201.16.12681.201.16.127126
3481.201.16.128/2581.201.16.129 to 81.201.16.25481.201.16.255126
3581.201.17.0/2581.201.17.1 to 81.201.17.12681.201.17.127126
3681.201.17.128/2581.201.17.129 to 81.201.17.25481.201.17.255126
3781.201.18.0/2581.201.18.1 to 81.201.18.12681.201.18.127126
3881.201.18.128/2581.201.18.129 to 81.201.18.25481.201.18.255126
3981.201.19.0/2581.201.19.1 to 81.201.19.12681.201.19.127126
4081.201.19.128/2581.201.19.129 to 81.201.19.25481.201.19.255126
4181.201.20.0/2581.201.20.1 to 81.201.20.12681.201.20.127126
4281.201.20.128/2581.201.20.129 to 81.201.20.25481.201.20.255126
4381.201.21.0/2581.201.21.1 to 81.201.21.12681.201.21.127126
4481.201.21.128/2581.201.21.129 to 81.201.21.25481.201.21.255126
4581.201.22.0/2581.201.22.1 to 81.201.22.12681.201.22.127126
4681.201.22.128/2581.201.22.129 to 81.201.22.25481.201.22.255126
4781.201.23.0/2581.201.23.1 to 81.201.23.12681.201.23.127126
4881.201.23.128/2581.201.23.129 to 81.201.23.25481.201.23.255126
4981.201.24.0/2581.201.24.1 to 81.201.24.12681.201.24.127126
5081.201.24.128/2581.201.24.129 to 81.201.24.25481.201.24.255126
5181.201.25.0/2581.201.25.1 to 81.201.25.12681.201.25.127126
5281.201.25.128/2581.201.25.129 to 81.201.25.25481.201.25.255126
5381.201.26.0/2581.201.26.1 to 81.201.26.12681.201.26.127126
5481.201.26.128/2581.201.26.129 to 81.201.26.25481.201.26.255126
5581.201.27.0/2581.201.27.1 to 81.201.27.12681.201.27.127126
5681.201.27.128/2581.201.27.129 to 81.201.27.25481.201.27.255126
5781.201.28.0/2581.201.28.1 to 81.201.28.12681.201.28.127126
5881.201.28.128/2581.201.28.129 to 81.201.28.25481.201.28.255126
5981.201.29.0/2581.201.29.1 to 81.201.29.12681.201.29.127126
6081.201.29.128/2581.201.29.129 to 81.201.29.25481.201.29.255126
6181.201.30.0/2581.201.30.1 to 81.201.30.12681.201.30.127126
6281.201.30.128/2581.201.30.129 to 81.201.30.25481.201.30.255126
6381.201.31.0/2581.201.31.1 to 81.201.31.12681.201.31.127126
6481.201.31.128/2581.201.31.129 to 81.201.31.25481.201.31.255126
6581.201.32.0/2581.201.32.1 to 81.201.32.12681.201.32.127126
6681.201.32.128/2581.201.32.129 to 81.201.32.25481.201.32.255126
6781.201.33.0/2581.201.33.1 to 81.201.33.12681.201.33.127126
6881.201.33.128/2581.201.33.129 to 81.201.33.25481.201.33.255126
6981.201.34.0/2581.201.34.1 to 81.201.34.12681.201.34.127126
7081.201.34.128/2581.201.34.129 to 81.201.34.25481.201.34.255126
7181.201.35.0/2581.201.35.1 to 81.201.35.12681.201.35.127126
7281.201.35.128/2581.201.35.129 to 81.201.35.25481.201.35.255126
7381.201.36.0/2581.201.36.1 to 81.201.36.12681.201.36.127126
7481.201.36.128/2581.201.36.129 to 81.201.36.25481.201.36.255126
7581.201.37.0/2581.201.37.1 to 81.201.37.12681.201.37.127126
7681.201.37.128/2581.201.37.129 to 81.201.37.25481.201.37.255126
7781.201.38.0/2581.201.38.1 to 81.201.38.12681.201.38.127126
7881.201.38.128/2581.201.38.129 to 81.201.38.25481.201.38.255126
7981.201.39.0/2581.201.39.1 to 81.201.39.12681.201.39.127126
8081.201.39.128/2581.201.39.129 to 81.201.39.25481.201.39.255126
8181.201.40.0/2581.201.40.1 to 81.201.40.12681.201.40.127126
8281.201.40.128/2581.201.40.129 to 81.201.40.25481.201.40.255126
8381.201.41.0/2581.201.41.1 to 81.201.41.12681.201.41.127126
8481.201.41.128/2581.201.41.129 to 81.201.41.25481.201.41.255126
8581.201.42.0/2581.201.42.1 to 81.201.42.12681.201.42.127126
8681.201.42.128/2581.201.42.129 to 81.201.42.25481.201.42.255126
8781.201.43.0/2581.201.43.1 to 81.201.43.12681.201.43.127126
8881.201.43.128/2581.201.43.129 to 81.201.43.25481.201.43.255126
8981.201.44.0/2581.201.44.1 to 81.201.44.12681.201.44.127126
9081.201.44.128/2581.201.44.129 to 81.201.44.25481.201.44.255126
9181.201.45.0/2581.201.45.1 to 81.201.45.12681.201.45.127126
9281.201.45.128/2581.201.45.129 to 81.201.45.25481.201.45.255126
9381.201.46.0/2581.201.46.1 to 81.201.46.12681.201.46.127126
9481.201.46.128/2581.201.46.129 to 81.201.46.25481.201.46.255126
9581.201.47.0/2581.201.47.1 to 81.201.47.12681.201.47.127126
9681.201.47.128/2581.201.47.129 to 81.201.47.25481.201.47.255126
9781.201.48.0/2581.201.48.1 to 81.201.48.12681.201.48.127126
9881.201.48.128/2581.201.48.129 to 81.201.48.25481.201.48.255126
9981.201.49.0/2581.201.49.1 to 81.201.49.12681.201.49.127126
10081.201.49.128/2581.201.49.129 to 81.201.49.25481.201.49.255126
10181.201.50.0/2581.201.50.1 to 81.201.50.12681.201.50.127126
10281.201.50.128/2581.201.50.129 to 81.201.50.25481.201.50.255126
10381.201.51.0/2581.201.51.1 to 81.201.51.12681.201.51.127126
10481.201.51.128/2581.201.51.129 to 81.201.51.25481.201.51.255126
10581.201.52.0/2581.201.52.1 to 81.201.52.12681.201.52.127126
10681.201.52.128/2581.201.52.129 to 81.201.52.25481.201.52.255126
10781.201.53.0/2581.201.53.1 to 81.201.53.12681.201.53.127126
10881.201.53.128/2581.201.53.129 to 81.201.53.25481.201.53.255126
10981.201.54.0/2581.201.54.1 to 81.201.54.12681.201.54.127126
11081.201.54.128/2581.201.54.129 to 81.201.54.25481.201.54.255126
11181.201.55.0/2581.201.55.1 to 81.201.55.12681.201.55.127126
11281.201.55.128/2581.201.55.129 to 81.201.55.25481.201.55.255126
11381.201.56.0/2581.201.56.1 to 81.201.56.12681.201.56.127126
11481.201.56.128/2581.201.56.129 to 81.201.56.25481.201.56.255126
11581.201.57.0/2581.201.57.1 to 81.201.57.12681.201.57.127126
11681.201.57.128/2581.201.57.129 to 81.201.57.25481.201.57.255126
11781.201.58.0/2581.201.58.1 to 81.201.58.12681.201.58.127126
11881.201.58.128/2581.201.58.129 to 81.201.58.25481.201.58.255126
11981.201.59.0/2581.201.59.1 to 81.201.59.12681.201.59.127126
12081.201.59.128/2581.201.59.129 to 81.201.59.25481.201.59.255126
12181.201.60.0/2581.201.60.1 to 81.201.60.12681.201.60.127126
12281.201.60.128/2581.201.60.129 to 81.201.60.25481.201.60.255126
12381.201.61.0/2581.201.61.1 to 81.201.61.12681.201.61.127126
12481.201.61.128/2581.201.61.129 to 81.201.61.25481.201.61.255126
12581.201.62.0/2581.201.62.1 to 81.201.62.12681.201.62.127126
12681.201.62.128/2581.201.62.129 to 81.201.62.25481.201.62.255126
12781.201.63.0/2581.201.63.1 to 81.201.63.12681.201.63.127126
12881.201.63.128/2581.201.63.129 to 81.201.63.25481.201.63.255126
12981.201.64.0/2581.201.64.1 to 81.201.64.12681.201.64.127126
13081.201.64.128/2581.201.64.129 to 81.201.64.25481.201.64.255126
13181.201.65.0/2581.201.65.1 to 81.201.65.12681.201.65.127126
13281.201.65.128/2581.201.65.129 to 81.201.65.25481.201.65.255126
13381.201.66.0/2581.201.66.1 to 81.201.66.12681.201.66.127126
13481.201.66.128/2581.201.66.129 to 81.201.66.25481.201.66.255126
13581.201.67.0/2581.201.67.1 to 81.201.67.12681.201.67.127126
13681.201.67.128/2581.201.67.129 to 81.201.67.25481.201.67.255126
13781.201.68.0/2581.201.68.1 to 81.201.68.12681.201.68.127126
13881.201.68.128/2581.201.68.129 to 81.201.68.25481.201.68.255126
13981.201.69.0/2581.201.69.1 to 81.201.69.12681.201.69.127126
14081.201.69.128/2581.201.69.129 to 81.201.69.25481.201.69.255126
14181.201.70.0/2581.201.70.1 to 81.201.70.12681.201.70.127126
14281.201.70.128/2581.201.70.129 to 81.201.70.25481.201.70.255126
14381.201.71.0/2581.201.71.1 to 81.201.71.12681.201.71.127126
14481.201.71.128/2581.201.71.129 to 81.201.71.25481.201.71.255126
14581.201.72.0/2581.201.72.1 to 81.201.72.12681.201.72.127126
14681.201.72.128/2581.201.72.129 to 81.201.72.25481.201.72.255126
14781.201.73.0/2581.201.73.1 to 81.201.73.12681.201.73.127126
14881.201.73.128/2581.201.73.129 to 81.201.73.25481.201.73.255126
14981.201.74.0/2581.201.74.1 to 81.201.74.12681.201.74.127126
15081.201.74.128/2581.201.74.129 to 81.201.74.25481.201.74.255126
15181.201.75.0/2581.201.75.1 to 81.201.75.12681.201.75.127126
15281.201.75.128/2581.201.75.129 to 81.201.75.25481.201.75.255126
15381.201.76.0/2581.201.76.1 to 81.201.76.12681.201.76.127126
15481.201.76.128/2581.201.76.129 to 81.201.76.25481.201.76.255126
15581.201.77.0/2581.201.77.1 to 81.201.77.12681.201.77.127126
15681.201.77.128/2581.201.77.129 to 81.201.77.25481.201.77.255126
15781.201.78.0/2581.201.78.1 to 81.201.78.12681.201.78.127126
15881.201.78.128/2581.201.78.129 to 81.201.78.25481.201.78.255126
15981.201.79.0/2581.201.79.1 to 81.201.79.12681.201.79.127126
16081.201.79.128/2581.201.79.129 to 81.201.79.25481.201.79.255126
16181.201.80.0/2581.201.80.1 to 81.201.80.12681.201.80.127126
16281.201.80.128/2581.201.80.129 to 81.201.80.25481.201.80.255126
16381.201.81.0/2581.201.81.1 to 81.201.81.12681.201.81.127126
16481.201.81.128/2581.201.81.129 to 81.201.81.25481.201.81.255126
16581.201.82.0/2581.201.82.1 to 81.201.82.12681.201.82.127126
16681.201.82.128/2581.201.82.129 to 81.201.82.25481.201.82.255126
16781.201.83.0/2581.201.83.1 to 81.201.83.12681.201.83.127126
16881.201.83.128/2581.201.83.129 to 81.201.83.25481.201.83.255126
16981.201.84.0/2581.201.84.1 to 81.201.84.12681.201.84.127126
17081.201.84.128/2581.201.84.129 to 81.201.84.25481.201.84.255126
17181.201.85.0/2581.201.85.1 to 81.201.85.12681.201.85.127126
17281.201.85.128/2581.201.85.129 to 81.201.85.25481.201.85.255126
17381.201.86.0/2581.201.86.1 to 81.201.86.12681.201.86.127126
17481.201.86.128/2581.201.86.129 to 81.201.86.25481.201.86.255126
17581.201.87.0/2581.201.87.1 to 81.201.87.12681.201.87.127126
17681.201.87.128/2581.201.87.129 to 81.201.87.25481.201.87.255126
17781.201.88.0/2581.201.88.1 to 81.201.88.12681.201.88.127126
17881.201.88.128/2581.201.88.129 to 81.201.88.25481.201.88.255126
17981.201.89.0/2581.201.89.1 to 81.201.89.12681.201.89.127126
18081.201.89.128/2581.201.89.129 to 81.201.89.25481.201.89.255126
18181.201.90.0/2581.201.90.1 to 81.201.90.12681.201.90.127126
18281.201.90.128/2581.201.90.129 to 81.201.90.25481.201.90.255126
18381.201.91.0/2581.201.91.1 to 81.201.91.12681.201.91.127126
18481.201.91.128/2581.201.91.129 to 81.201.91.25481.201.91.255126
18581.201.92.0/2581.201.92.1 to 81.201.92.12681.201.92.127126
18681.201.92.128/2581.201.92.129 to 81.201.92.25481.201.92.255126
18781.201.93.0/2581.201.93.1 to 81.201.93.12681.201.93.127126
18881.201.93.128/2581.201.93.129 to 81.201.93.25481.201.93.255126
18981.201.94.0/2581.201.94.1 to 81.201.94.12681.201.94.127126
19081.201.94.128/2581.201.94.129 to 81.201.94.25481.201.94.255126
19181.201.95.0/2581.201.95.1 to 81.201.95.12681.201.95.127126
19281.201.95.128/2581.201.95.129 to 81.201.95.25481.201.95.255126
19381.201.96.0/2581.201.96.1 to 81.201.96.12681.201.96.127126
19481.201.96.128/2581.201.96.129 to 81.201.96.25481.201.96.255126
19581.201.97.0/2581.201.97.1 to 81.201.97.12681.201.97.127126
19681.201.97.128/2581.201.97.129 to 81.201.97.25481.201.97.255126
19781.201.98.0/2581.201.98.1 to 81.201.98.12681.201.98.127126
19881.201.98.128/2581.201.98.129 to 81.201.98.25481.201.98.255126
19981.201.99.0/2581.201.99.1 to 81.201.99.12681.201.99.127126
20081.201.99.128/2581.201.99.129 to 81.201.99.25481.201.99.255126
20181.201.100.0/2581.201.100.1 to 81.201.100.12681.201.100.127126
20281.201.100.128/2581.201.100.129 to 81.201.100.25481.201.100.255126
20381.201.101.0/2581.201.101.1 to 81.201.101.12681.201.101.127126
20481.201.101.128/2581.201.101.129 to 81.201.101.25481.201.101.255126
20581.201.102.0/2581.201.102.1 to 81.201.102.12681.201.102.127126
20681.201.102.128/2581.201.102.129 to 81.201.102.25481.201.102.255126
20781.201.103.0/2581.201.103.1 to 81.201.103.12681.201.103.127126
20881.201.103.128/2581.201.103.129 to 81.201.103.25481.201.103.255126
20981.201.104.0/2581.201.104.1 to 81.201.104.12681.201.104.127126
21081.201.104.128/2581.201.104.129 to 81.201.104.25481.201.104.255126
21181.201.105.0/2581.201.105.1 to 81.201.105.12681.201.105.127126
21281.201.105.128/2581.201.105.129 to 81.201.105.25481.201.105.255126
21381.201.106.0/2581.201.106.1 to 81.201.106.12681.201.106.127126
21481.201.106.128/2581.201.106.129 to 81.201.106.25481.201.106.255126
21581.201.107.0/2581.201.107.1 to 81.201.107.12681.201.107.127126
21681.201.107.128/2581.201.107.129 to 81.201.107.25481.201.107.255126
21781.201.108.0/2581.201.108.1 to 81.201.108.12681.201.108.127126
21881.201.108.128/2581.201.108.129 to 81.201.108.25481.201.108.255126
21981.201.109.0/2581.201.109.1 to 81.201.109.12681.201.109.127126
22081.201.109.128/2581.201.109.129 to 81.201.109.25481.201.109.255126
22181.201.110.0/2581.201.110.1 to 81.201.110.12681.201.110.127126
22281.201.110.128/2581.201.110.129 to 81.201.110.25481.201.110.255126
22381.201.111.0/2581.201.111.1 to 81.201.111.12681.201.111.127126
22481.201.111.128/2581.201.111.129 to 81.201.111.25481.201.111.255126
22581.201.112.0/2581.201.112.1 to 81.201.112.12681.201.112.127126
22681.201.112.128/2581.201.112.129 to 81.201.112.25481.201.112.255126
22781.201.113.0/2581.201.113.1 to 81.201.113.12681.201.113.127126
22881.201.113.128/2581.201.113.129 to 81.201.113.25481.201.113.255126
22981.201.114.0/2581.201.114.1 to 81.201.114.12681.201.114.127126
23081.201.114.128/2581.201.114.129 to 81.201.114.25481.201.114.255126
23181.201.115.0/2581.201.115.1 to 81.201.115.12681.201.115.127126
23281.201.115.128/2581.201.115.129 to 81.201.115.25481.201.115.255126
23381.201.116.0/2581.201.116.1 to 81.201.116.12681.201.116.127126
23481.201.116.128/2581.201.116.129 to 81.201.116.25481.201.116.255126
23581.201.117.0/2581.201.117.1 to 81.201.117.12681.201.117.127126
23681.201.117.128/2581.201.117.129 to 81.201.117.25481.201.117.255126
23781.201.118.0/2581.201.118.1 to 81.201.118.12681.201.118.127126
23881.201.118.128/2581.201.118.129 to 81.201.118.25481.201.118.255126
23981.201.119.0/2581.201.119.1 to 81.201.119.12681.201.119.127126
24081.201.119.128/2581.201.119.129 to 81.201.119.25481.201.119.255126
24181.201.120.0/2581.201.120.1 to 81.201.120.12681.201.120.127126
24281.201.120.128/2581.201.120.129 to 81.201.120.25481.201.120.255126
24381.201.121.0/2581.201.121.1 to 81.201.121.12681.201.121.127126
24481.201.121.128/2581.201.121.129 to 81.201.121.25481.201.121.255126
24581.201.122.0/2581.201.122.1 to 81.201.122.12681.201.122.127126
24681.201.122.128/2581.201.122.129 to 81.201.122.25481.201.122.255126
24781.201.123.0/2581.201.123.1 to 81.201.123.12681.201.123.127126
24881.201.123.128/2581.201.123.129 to 81.201.123.25481.201.123.255126
24981.201.124.0/2581.201.124.1 to 81.201.124.12681.201.124.127126
25081.201.124.128/2581.201.124.129 to 81.201.124.25481.201.124.255126
25181.201.125.0/2581.201.125.1 to 81.201.125.12681.201.125.127126
25281.201.125.128/2581.201.125.129 to 81.201.125.25481.201.125.255126
25381.201.126.0/2581.201.126.1 to 81.201.126.12681.201.126.127126
25481.201.126.128/2581.201.126.129 to 81.201.126.25481.201.126.255126
25581.201.127.0/2581.201.127.1 to 81.201.127.12681.201.127.127126
25681.201.127.128/2581.201.127.129 to 81.201.127.25481.201.127.255126

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.