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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.

Network23.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
23.0.0.0
Broadcast address
23.255.255.255
First usable
23.0.0.1
Last usable
23.255.255.254
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 17000000 · Integer 385875968 to 402653183
Reverse DNS zone
23.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010111..00000000.00000000.0000000023.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00010111..00000000.00000000.0000000023.0.0.0
Broadcast00010111..11111111.11111111.1111111123.255.255.255
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)

23.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.0.0.0/1723.0.0.1 to 23.0.127.25423.0.127.25532,766
223.0.128.0/1723.0.128.1 to 23.0.255.25423.0.255.25532,766
323.1.0.0/1723.1.0.1 to 23.1.127.25423.1.127.25532,766
423.1.128.0/1723.1.128.1 to 23.1.255.25423.1.255.25532,766
523.2.0.0/1723.2.0.1 to 23.2.127.25423.2.127.25532,766
623.2.128.0/1723.2.128.1 to 23.2.255.25423.2.255.25532,766
723.3.0.0/1723.3.0.1 to 23.3.127.25423.3.127.25532,766
823.3.128.0/1723.3.128.1 to 23.3.255.25423.3.255.25532,766
923.4.0.0/1723.4.0.1 to 23.4.127.25423.4.127.25532,766
1023.4.128.0/1723.4.128.1 to 23.4.255.25423.4.255.25532,766
1123.5.0.0/1723.5.0.1 to 23.5.127.25423.5.127.25532,766
1223.5.128.0/1723.5.128.1 to 23.5.255.25423.5.255.25532,766
1323.6.0.0/1723.6.0.1 to 23.6.127.25423.6.127.25532,766
1423.6.128.0/1723.6.128.1 to 23.6.255.25423.6.255.25532,766
1523.7.0.0/1723.7.0.1 to 23.7.127.25423.7.127.25532,766
1623.7.128.0/1723.7.128.1 to 23.7.255.25423.7.255.25532,766
1723.8.0.0/1723.8.0.1 to 23.8.127.25423.8.127.25532,766
1823.8.128.0/1723.8.128.1 to 23.8.255.25423.8.255.25532,766
1923.9.0.0/1723.9.0.1 to 23.9.127.25423.9.127.25532,766
2023.9.128.0/1723.9.128.1 to 23.9.255.25423.9.255.25532,766
2123.10.0.0/1723.10.0.1 to 23.10.127.25423.10.127.25532,766
2223.10.128.0/1723.10.128.1 to 23.10.255.25423.10.255.25532,766
2323.11.0.0/1723.11.0.1 to 23.11.127.25423.11.127.25532,766
2423.11.128.0/1723.11.128.1 to 23.11.255.25423.11.255.25532,766
2523.12.0.0/1723.12.0.1 to 23.12.127.25423.12.127.25532,766
2623.12.128.0/1723.12.128.1 to 23.12.255.25423.12.255.25532,766
2723.13.0.0/1723.13.0.1 to 23.13.127.25423.13.127.25532,766
2823.13.128.0/1723.13.128.1 to 23.13.255.25423.13.255.25532,766
2923.14.0.0/1723.14.0.1 to 23.14.127.25423.14.127.25532,766
3023.14.128.0/1723.14.128.1 to 23.14.255.25423.14.255.25532,766
3123.15.0.0/1723.15.0.1 to 23.15.127.25423.15.127.25532,766
3223.15.128.0/1723.15.128.1 to 23.15.255.25423.15.255.25532,766
3323.16.0.0/1723.16.0.1 to 23.16.127.25423.16.127.25532,766
3423.16.128.0/1723.16.128.1 to 23.16.255.25423.16.255.25532,766
3523.17.0.0/1723.17.0.1 to 23.17.127.25423.17.127.25532,766
3623.17.128.0/1723.17.128.1 to 23.17.255.25423.17.255.25532,766
3723.18.0.0/1723.18.0.1 to 23.18.127.25423.18.127.25532,766
3823.18.128.0/1723.18.128.1 to 23.18.255.25423.18.255.25532,766
3923.19.0.0/1723.19.0.1 to 23.19.127.25423.19.127.25532,766
4023.19.128.0/1723.19.128.1 to 23.19.255.25423.19.255.25532,766
4123.20.0.0/1723.20.0.1 to 23.20.127.25423.20.127.25532,766
4223.20.128.0/1723.20.128.1 to 23.20.255.25423.20.255.25532,766
4323.21.0.0/1723.21.0.1 to 23.21.127.25423.21.127.25532,766
4423.21.128.0/1723.21.128.1 to 23.21.255.25423.21.255.25532,766
4523.22.0.0/1723.22.0.1 to 23.22.127.25423.22.127.25532,766
4623.22.128.0/1723.22.128.1 to 23.22.255.25423.22.255.25532,766
4723.23.0.0/1723.23.0.1 to 23.23.127.25423.23.127.25532,766
4823.23.128.0/1723.23.128.1 to 23.23.255.25423.23.255.25532,766
4923.24.0.0/1723.24.0.1 to 23.24.127.25423.24.127.25532,766
5023.24.128.0/1723.24.128.1 to 23.24.255.25423.24.255.25532,766
5123.25.0.0/1723.25.0.1 to 23.25.127.25423.25.127.25532,766
5223.25.128.0/1723.25.128.1 to 23.25.255.25423.25.255.25532,766
5323.26.0.0/1723.26.0.1 to 23.26.127.25423.26.127.25532,766
5423.26.128.0/1723.26.128.1 to 23.26.255.25423.26.255.25532,766
5523.27.0.0/1723.27.0.1 to 23.27.127.25423.27.127.25532,766
5623.27.128.0/1723.27.128.1 to 23.27.255.25423.27.255.25532,766
5723.28.0.0/1723.28.0.1 to 23.28.127.25423.28.127.25532,766
5823.28.128.0/1723.28.128.1 to 23.28.255.25423.28.255.25532,766
5923.29.0.0/1723.29.0.1 to 23.29.127.25423.29.127.25532,766
6023.29.128.0/1723.29.128.1 to 23.29.255.25423.29.255.25532,766
6123.30.0.0/1723.30.0.1 to 23.30.127.25423.30.127.25532,766
6223.30.128.0/1723.30.128.1 to 23.30.255.25423.30.255.25532,766
6323.31.0.0/1723.31.0.1 to 23.31.127.25423.31.127.25532,766
6423.31.128.0/1723.31.128.1 to 23.31.255.25423.31.255.25532,766
6523.32.0.0/1723.32.0.1 to 23.32.127.25423.32.127.25532,766
6623.32.128.0/1723.32.128.1 to 23.32.255.25423.32.255.25532,766
6723.33.0.0/1723.33.0.1 to 23.33.127.25423.33.127.25532,766
6823.33.128.0/1723.33.128.1 to 23.33.255.25423.33.255.25532,766
6923.34.0.0/1723.34.0.1 to 23.34.127.25423.34.127.25532,766
7023.34.128.0/1723.34.128.1 to 23.34.255.25423.34.255.25532,766
7123.35.0.0/1723.35.0.1 to 23.35.127.25423.35.127.25532,766
7223.35.128.0/1723.35.128.1 to 23.35.255.25423.35.255.25532,766
7323.36.0.0/1723.36.0.1 to 23.36.127.25423.36.127.25532,766
7423.36.128.0/1723.36.128.1 to 23.36.255.25423.36.255.25532,766
7523.37.0.0/1723.37.0.1 to 23.37.127.25423.37.127.25532,766
7623.37.128.0/1723.37.128.1 to 23.37.255.25423.37.255.25532,766
7723.38.0.0/1723.38.0.1 to 23.38.127.25423.38.127.25532,766
7823.38.128.0/1723.38.128.1 to 23.38.255.25423.38.255.25532,766
7923.39.0.0/1723.39.0.1 to 23.39.127.25423.39.127.25532,766
8023.39.128.0/1723.39.128.1 to 23.39.255.25423.39.255.25532,766
8123.40.0.0/1723.40.0.1 to 23.40.127.25423.40.127.25532,766
8223.40.128.0/1723.40.128.1 to 23.40.255.25423.40.255.25532,766
8323.41.0.0/1723.41.0.1 to 23.41.127.25423.41.127.25532,766
8423.41.128.0/1723.41.128.1 to 23.41.255.25423.41.255.25532,766
8523.42.0.0/1723.42.0.1 to 23.42.127.25423.42.127.25532,766
8623.42.128.0/1723.42.128.1 to 23.42.255.25423.42.255.25532,766
8723.43.0.0/1723.43.0.1 to 23.43.127.25423.43.127.25532,766
8823.43.128.0/1723.43.128.1 to 23.43.255.25423.43.255.25532,766
8923.44.0.0/1723.44.0.1 to 23.44.127.25423.44.127.25532,766
9023.44.128.0/1723.44.128.1 to 23.44.255.25423.44.255.25532,766
9123.45.0.0/1723.45.0.1 to 23.45.127.25423.45.127.25532,766
9223.45.128.0/1723.45.128.1 to 23.45.255.25423.45.255.25532,766
9323.46.0.0/1723.46.0.1 to 23.46.127.25423.46.127.25532,766
9423.46.128.0/1723.46.128.1 to 23.46.255.25423.46.255.25532,766
9523.47.0.0/1723.47.0.1 to 23.47.127.25423.47.127.25532,766
9623.47.128.0/1723.47.128.1 to 23.47.255.25423.47.255.25532,766
9723.48.0.0/1723.48.0.1 to 23.48.127.25423.48.127.25532,766
9823.48.128.0/1723.48.128.1 to 23.48.255.25423.48.255.25532,766
9923.49.0.0/1723.49.0.1 to 23.49.127.25423.49.127.25532,766
10023.49.128.0/1723.49.128.1 to 23.49.255.25423.49.255.25532,766
10123.50.0.0/1723.50.0.1 to 23.50.127.25423.50.127.25532,766
10223.50.128.0/1723.50.128.1 to 23.50.255.25423.50.255.25532,766
10323.51.0.0/1723.51.0.1 to 23.51.127.25423.51.127.25532,766
10423.51.128.0/1723.51.128.1 to 23.51.255.25423.51.255.25532,766
10523.52.0.0/1723.52.0.1 to 23.52.127.25423.52.127.25532,766
10623.52.128.0/1723.52.128.1 to 23.52.255.25423.52.255.25532,766
10723.53.0.0/1723.53.0.1 to 23.53.127.25423.53.127.25532,766
10823.53.128.0/1723.53.128.1 to 23.53.255.25423.53.255.25532,766
10923.54.0.0/1723.54.0.1 to 23.54.127.25423.54.127.25532,766
11023.54.128.0/1723.54.128.1 to 23.54.255.25423.54.255.25532,766
11123.55.0.0/1723.55.0.1 to 23.55.127.25423.55.127.25532,766
11223.55.128.0/1723.55.128.1 to 23.55.255.25423.55.255.25532,766
11323.56.0.0/1723.56.0.1 to 23.56.127.25423.56.127.25532,766
11423.56.128.0/1723.56.128.1 to 23.56.255.25423.56.255.25532,766
11523.57.0.0/1723.57.0.1 to 23.57.127.25423.57.127.25532,766
11623.57.128.0/1723.57.128.1 to 23.57.255.25423.57.255.25532,766
11723.58.0.0/1723.58.0.1 to 23.58.127.25423.58.127.25532,766
11823.58.128.0/1723.58.128.1 to 23.58.255.25423.58.255.25532,766
11923.59.0.0/1723.59.0.1 to 23.59.127.25423.59.127.25532,766
12023.59.128.0/1723.59.128.1 to 23.59.255.25423.59.255.25532,766
12123.60.0.0/1723.60.0.1 to 23.60.127.25423.60.127.25532,766
12223.60.128.0/1723.60.128.1 to 23.60.255.25423.60.255.25532,766
12323.61.0.0/1723.61.0.1 to 23.61.127.25423.61.127.25532,766
12423.61.128.0/1723.61.128.1 to 23.61.255.25423.61.255.25532,766
12523.62.0.0/1723.62.0.1 to 23.62.127.25423.62.127.25532,766
12623.62.128.0/1723.62.128.1 to 23.62.255.25423.62.255.25532,766
12723.63.0.0/1723.63.0.1 to 23.63.127.25423.63.127.25532,766
12823.63.128.0/1723.63.128.1 to 23.63.255.25423.63.255.25532,766
12923.64.0.0/1723.64.0.1 to 23.64.127.25423.64.127.25532,766
13023.64.128.0/1723.64.128.1 to 23.64.255.25423.64.255.25532,766
13123.65.0.0/1723.65.0.1 to 23.65.127.25423.65.127.25532,766
13223.65.128.0/1723.65.128.1 to 23.65.255.25423.65.255.25532,766
13323.66.0.0/1723.66.0.1 to 23.66.127.25423.66.127.25532,766
13423.66.128.0/1723.66.128.1 to 23.66.255.25423.66.255.25532,766
13523.67.0.0/1723.67.0.1 to 23.67.127.25423.67.127.25532,766
13623.67.128.0/1723.67.128.1 to 23.67.255.25423.67.255.25532,766
13723.68.0.0/1723.68.0.1 to 23.68.127.25423.68.127.25532,766
13823.68.128.0/1723.68.128.1 to 23.68.255.25423.68.255.25532,766
13923.69.0.0/1723.69.0.1 to 23.69.127.25423.69.127.25532,766
14023.69.128.0/1723.69.128.1 to 23.69.255.25423.69.255.25532,766
14123.70.0.0/1723.70.0.1 to 23.70.127.25423.70.127.25532,766
14223.70.128.0/1723.70.128.1 to 23.70.255.25423.70.255.25532,766
14323.71.0.0/1723.71.0.1 to 23.71.127.25423.71.127.25532,766
14423.71.128.0/1723.71.128.1 to 23.71.255.25423.71.255.25532,766
14523.72.0.0/1723.72.0.1 to 23.72.127.25423.72.127.25532,766
14623.72.128.0/1723.72.128.1 to 23.72.255.25423.72.255.25532,766
14723.73.0.0/1723.73.0.1 to 23.73.127.25423.73.127.25532,766
14823.73.128.0/1723.73.128.1 to 23.73.255.25423.73.255.25532,766
14923.74.0.0/1723.74.0.1 to 23.74.127.25423.74.127.25532,766
15023.74.128.0/1723.74.128.1 to 23.74.255.25423.74.255.25532,766
15123.75.0.0/1723.75.0.1 to 23.75.127.25423.75.127.25532,766
15223.75.128.0/1723.75.128.1 to 23.75.255.25423.75.255.25532,766
15323.76.0.0/1723.76.0.1 to 23.76.127.25423.76.127.25532,766
15423.76.128.0/1723.76.128.1 to 23.76.255.25423.76.255.25532,766
15523.77.0.0/1723.77.0.1 to 23.77.127.25423.77.127.25532,766
15623.77.128.0/1723.77.128.1 to 23.77.255.25423.77.255.25532,766
15723.78.0.0/1723.78.0.1 to 23.78.127.25423.78.127.25532,766
15823.78.128.0/1723.78.128.1 to 23.78.255.25423.78.255.25532,766
15923.79.0.0/1723.79.0.1 to 23.79.127.25423.79.127.25532,766
16023.79.128.0/1723.79.128.1 to 23.79.255.25423.79.255.25532,766
16123.80.0.0/1723.80.0.1 to 23.80.127.25423.80.127.25532,766
16223.80.128.0/1723.80.128.1 to 23.80.255.25423.80.255.25532,766
16323.81.0.0/1723.81.0.1 to 23.81.127.25423.81.127.25532,766
16423.81.128.0/1723.81.128.1 to 23.81.255.25423.81.255.25532,766
16523.82.0.0/1723.82.0.1 to 23.82.127.25423.82.127.25532,766
16623.82.128.0/1723.82.128.1 to 23.82.255.25423.82.255.25532,766
16723.83.0.0/1723.83.0.1 to 23.83.127.25423.83.127.25532,766
16823.83.128.0/1723.83.128.1 to 23.83.255.25423.83.255.25532,766
16923.84.0.0/1723.84.0.1 to 23.84.127.25423.84.127.25532,766
17023.84.128.0/1723.84.128.1 to 23.84.255.25423.84.255.25532,766
17123.85.0.0/1723.85.0.1 to 23.85.127.25423.85.127.25532,766
17223.85.128.0/1723.85.128.1 to 23.85.255.25423.85.255.25532,766
17323.86.0.0/1723.86.0.1 to 23.86.127.25423.86.127.25532,766
17423.86.128.0/1723.86.128.1 to 23.86.255.25423.86.255.25532,766
17523.87.0.0/1723.87.0.1 to 23.87.127.25423.87.127.25532,766
17623.87.128.0/1723.87.128.1 to 23.87.255.25423.87.255.25532,766
17723.88.0.0/1723.88.0.1 to 23.88.127.25423.88.127.25532,766
17823.88.128.0/1723.88.128.1 to 23.88.255.25423.88.255.25532,766
17923.89.0.0/1723.89.0.1 to 23.89.127.25423.89.127.25532,766
18023.89.128.0/1723.89.128.1 to 23.89.255.25423.89.255.25532,766
18123.90.0.0/1723.90.0.1 to 23.90.127.25423.90.127.25532,766
18223.90.128.0/1723.90.128.1 to 23.90.255.25423.90.255.25532,766
18323.91.0.0/1723.91.0.1 to 23.91.127.25423.91.127.25532,766
18423.91.128.0/1723.91.128.1 to 23.91.255.25423.91.255.25532,766
18523.92.0.0/1723.92.0.1 to 23.92.127.25423.92.127.25532,766
18623.92.128.0/1723.92.128.1 to 23.92.255.25423.92.255.25532,766
18723.93.0.0/1723.93.0.1 to 23.93.127.25423.93.127.25532,766
18823.93.128.0/1723.93.128.1 to 23.93.255.25423.93.255.25532,766
18923.94.0.0/1723.94.0.1 to 23.94.127.25423.94.127.25532,766
19023.94.128.0/1723.94.128.1 to 23.94.255.25423.94.255.25532,766
19123.95.0.0/1723.95.0.1 to 23.95.127.25423.95.127.25532,766
19223.95.128.0/1723.95.128.1 to 23.95.255.25423.95.255.25532,766
19323.96.0.0/1723.96.0.1 to 23.96.127.25423.96.127.25532,766
19423.96.128.0/1723.96.128.1 to 23.96.255.25423.96.255.25532,766
19523.97.0.0/1723.97.0.1 to 23.97.127.25423.97.127.25532,766
19623.97.128.0/1723.97.128.1 to 23.97.255.25423.97.255.25532,766
19723.98.0.0/1723.98.0.1 to 23.98.127.25423.98.127.25532,766
19823.98.128.0/1723.98.128.1 to 23.98.255.25423.98.255.25532,766
19923.99.0.0/1723.99.0.1 to 23.99.127.25423.99.127.25532,766
20023.99.128.0/1723.99.128.1 to 23.99.255.25423.99.255.25532,766
20123.100.0.0/1723.100.0.1 to 23.100.127.25423.100.127.25532,766
20223.100.128.0/1723.100.128.1 to 23.100.255.25423.100.255.25532,766
20323.101.0.0/1723.101.0.1 to 23.101.127.25423.101.127.25532,766
20423.101.128.0/1723.101.128.1 to 23.101.255.25423.101.255.25532,766
20523.102.0.0/1723.102.0.1 to 23.102.127.25423.102.127.25532,766
20623.102.128.0/1723.102.128.1 to 23.102.255.25423.102.255.25532,766
20723.103.0.0/1723.103.0.1 to 23.103.127.25423.103.127.25532,766
20823.103.128.0/1723.103.128.1 to 23.103.255.25423.103.255.25532,766
20923.104.0.0/1723.104.0.1 to 23.104.127.25423.104.127.25532,766
21023.104.128.0/1723.104.128.1 to 23.104.255.25423.104.255.25532,766
21123.105.0.0/1723.105.0.1 to 23.105.127.25423.105.127.25532,766
21223.105.128.0/1723.105.128.1 to 23.105.255.25423.105.255.25532,766
21323.106.0.0/1723.106.0.1 to 23.106.127.25423.106.127.25532,766
21423.106.128.0/1723.106.128.1 to 23.106.255.25423.106.255.25532,766
21523.107.0.0/1723.107.0.1 to 23.107.127.25423.107.127.25532,766
21623.107.128.0/1723.107.128.1 to 23.107.255.25423.107.255.25532,766
21723.108.0.0/1723.108.0.1 to 23.108.127.25423.108.127.25532,766
21823.108.128.0/1723.108.128.1 to 23.108.255.25423.108.255.25532,766
21923.109.0.0/1723.109.0.1 to 23.109.127.25423.109.127.25532,766
22023.109.128.0/1723.109.128.1 to 23.109.255.25423.109.255.25532,766
22123.110.0.0/1723.110.0.1 to 23.110.127.25423.110.127.25532,766
22223.110.128.0/1723.110.128.1 to 23.110.255.25423.110.255.25532,766
22323.111.0.0/1723.111.0.1 to 23.111.127.25423.111.127.25532,766
22423.111.128.0/1723.111.128.1 to 23.111.255.25423.111.255.25532,766
22523.112.0.0/1723.112.0.1 to 23.112.127.25423.112.127.25532,766
22623.112.128.0/1723.112.128.1 to 23.112.255.25423.112.255.25532,766
22723.113.0.0/1723.113.0.1 to 23.113.127.25423.113.127.25532,766
22823.113.128.0/1723.113.128.1 to 23.113.255.25423.113.255.25532,766
22923.114.0.0/1723.114.0.1 to 23.114.127.25423.114.127.25532,766
23023.114.128.0/1723.114.128.1 to 23.114.255.25423.114.255.25532,766
23123.115.0.0/1723.115.0.1 to 23.115.127.25423.115.127.25532,766
23223.115.128.0/1723.115.128.1 to 23.115.255.25423.115.255.25532,766
23323.116.0.0/1723.116.0.1 to 23.116.127.25423.116.127.25532,766
23423.116.128.0/1723.116.128.1 to 23.116.255.25423.116.255.25532,766
23523.117.0.0/1723.117.0.1 to 23.117.127.25423.117.127.25532,766
23623.117.128.0/1723.117.128.1 to 23.117.255.25423.117.255.25532,766
23723.118.0.0/1723.118.0.1 to 23.118.127.25423.118.127.25532,766
23823.118.128.0/1723.118.128.1 to 23.118.255.25423.118.255.25532,766
23923.119.0.0/1723.119.0.1 to 23.119.127.25423.119.127.25532,766
24023.119.128.0/1723.119.128.1 to 23.119.255.25423.119.255.25532,766
24123.120.0.0/1723.120.0.1 to 23.120.127.25423.120.127.25532,766
24223.120.128.0/1723.120.128.1 to 23.120.255.25423.120.255.25532,766
24323.121.0.0/1723.121.0.1 to 23.121.127.25423.121.127.25532,766
24423.121.128.0/1723.121.128.1 to 23.121.255.25423.121.255.25532,766
24523.122.0.0/1723.122.0.1 to 23.122.127.25423.122.127.25532,766
24623.122.128.0/1723.122.128.1 to 23.122.255.25423.122.255.25532,766
24723.123.0.0/1723.123.0.1 to 23.123.127.25423.123.127.25532,766
24823.123.128.0/1723.123.128.1 to 23.123.255.25423.123.255.25532,766
24923.124.0.0/1723.124.0.1 to 23.124.127.25423.124.127.25532,766
25023.124.128.0/1723.124.128.1 to 23.124.255.25423.124.255.25532,766
25123.125.0.0/1723.125.0.1 to 23.125.127.25423.125.127.25532,766
25223.125.128.0/1723.125.128.1 to 23.125.255.25423.125.255.25532,766
25323.126.0.0/1723.126.0.1 to 23.126.127.25423.126.127.25532,766
25423.126.128.0/1723.126.128.1 to 23.126.255.25423.126.255.25532,766
25523.127.0.0/1723.127.0.1 to 23.127.127.25423.127.127.25532,766
25623.127.128.0/1723.127.128.1 to 23.127.255.25423.127.255.25532,766

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.