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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.

Network12.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
12.0.0.0
Broadcast address
12.255.255.255
First usable
12.0.0.1
Last usable
12.255.255.254
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 0C000000 · Integer 201326592 to 218103807
Reverse DNS zone
12.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001100..00000000.00000000.0000000012.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00001100..00000000.00000000.0000000012.0.0.0
Broadcast00001100..11111111.11111111.1111111112.255.255.255
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)

12.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
112.0.0.0/1712.0.0.1 to 12.0.127.25412.0.127.25532,766
212.0.128.0/1712.0.128.1 to 12.0.255.25412.0.255.25532,766
312.1.0.0/1712.1.0.1 to 12.1.127.25412.1.127.25532,766
412.1.128.0/1712.1.128.1 to 12.1.255.25412.1.255.25532,766
512.2.0.0/1712.2.0.1 to 12.2.127.25412.2.127.25532,766
612.2.128.0/1712.2.128.1 to 12.2.255.25412.2.255.25532,766
712.3.0.0/1712.3.0.1 to 12.3.127.25412.3.127.25532,766
812.3.128.0/1712.3.128.1 to 12.3.255.25412.3.255.25532,766
912.4.0.0/1712.4.0.1 to 12.4.127.25412.4.127.25532,766
1012.4.128.0/1712.4.128.1 to 12.4.255.25412.4.255.25532,766
1112.5.0.0/1712.5.0.1 to 12.5.127.25412.5.127.25532,766
1212.5.128.0/1712.5.128.1 to 12.5.255.25412.5.255.25532,766
1312.6.0.0/1712.6.0.1 to 12.6.127.25412.6.127.25532,766
1412.6.128.0/1712.6.128.1 to 12.6.255.25412.6.255.25532,766
1512.7.0.0/1712.7.0.1 to 12.7.127.25412.7.127.25532,766
1612.7.128.0/1712.7.128.1 to 12.7.255.25412.7.255.25532,766
1712.8.0.0/1712.8.0.1 to 12.8.127.25412.8.127.25532,766
1812.8.128.0/1712.8.128.1 to 12.8.255.25412.8.255.25532,766
1912.9.0.0/1712.9.0.1 to 12.9.127.25412.9.127.25532,766
2012.9.128.0/1712.9.128.1 to 12.9.255.25412.9.255.25532,766
2112.10.0.0/1712.10.0.1 to 12.10.127.25412.10.127.25532,766
2212.10.128.0/1712.10.128.1 to 12.10.255.25412.10.255.25532,766
2312.11.0.0/1712.11.0.1 to 12.11.127.25412.11.127.25532,766
2412.11.128.0/1712.11.128.1 to 12.11.255.25412.11.255.25532,766
2512.12.0.0/1712.12.0.1 to 12.12.127.25412.12.127.25532,766
2612.12.128.0/1712.12.128.1 to 12.12.255.25412.12.255.25532,766
2712.13.0.0/1712.13.0.1 to 12.13.127.25412.13.127.25532,766
2812.13.128.0/1712.13.128.1 to 12.13.255.25412.13.255.25532,766
2912.14.0.0/1712.14.0.1 to 12.14.127.25412.14.127.25532,766
3012.14.128.0/1712.14.128.1 to 12.14.255.25412.14.255.25532,766
3112.15.0.0/1712.15.0.1 to 12.15.127.25412.15.127.25532,766
3212.15.128.0/1712.15.128.1 to 12.15.255.25412.15.255.25532,766
3312.16.0.0/1712.16.0.1 to 12.16.127.25412.16.127.25532,766
3412.16.128.0/1712.16.128.1 to 12.16.255.25412.16.255.25532,766
3512.17.0.0/1712.17.0.1 to 12.17.127.25412.17.127.25532,766
3612.17.128.0/1712.17.128.1 to 12.17.255.25412.17.255.25532,766
3712.18.0.0/1712.18.0.1 to 12.18.127.25412.18.127.25532,766
3812.18.128.0/1712.18.128.1 to 12.18.255.25412.18.255.25532,766
3912.19.0.0/1712.19.0.1 to 12.19.127.25412.19.127.25532,766
4012.19.128.0/1712.19.128.1 to 12.19.255.25412.19.255.25532,766
4112.20.0.0/1712.20.0.1 to 12.20.127.25412.20.127.25532,766
4212.20.128.0/1712.20.128.1 to 12.20.255.25412.20.255.25532,766
4312.21.0.0/1712.21.0.1 to 12.21.127.25412.21.127.25532,766
4412.21.128.0/1712.21.128.1 to 12.21.255.25412.21.255.25532,766
4512.22.0.0/1712.22.0.1 to 12.22.127.25412.22.127.25532,766
4612.22.128.0/1712.22.128.1 to 12.22.255.25412.22.255.25532,766
4712.23.0.0/1712.23.0.1 to 12.23.127.25412.23.127.25532,766
4812.23.128.0/1712.23.128.1 to 12.23.255.25412.23.255.25532,766
4912.24.0.0/1712.24.0.1 to 12.24.127.25412.24.127.25532,766
5012.24.128.0/1712.24.128.1 to 12.24.255.25412.24.255.25532,766
5112.25.0.0/1712.25.0.1 to 12.25.127.25412.25.127.25532,766
5212.25.128.0/1712.25.128.1 to 12.25.255.25412.25.255.25532,766
5312.26.0.0/1712.26.0.1 to 12.26.127.25412.26.127.25532,766
5412.26.128.0/1712.26.128.1 to 12.26.255.25412.26.255.25532,766
5512.27.0.0/1712.27.0.1 to 12.27.127.25412.27.127.25532,766
5612.27.128.0/1712.27.128.1 to 12.27.255.25412.27.255.25532,766
5712.28.0.0/1712.28.0.1 to 12.28.127.25412.28.127.25532,766
5812.28.128.0/1712.28.128.1 to 12.28.255.25412.28.255.25532,766
5912.29.0.0/1712.29.0.1 to 12.29.127.25412.29.127.25532,766
6012.29.128.0/1712.29.128.1 to 12.29.255.25412.29.255.25532,766
6112.30.0.0/1712.30.0.1 to 12.30.127.25412.30.127.25532,766
6212.30.128.0/1712.30.128.1 to 12.30.255.25412.30.255.25532,766
6312.31.0.0/1712.31.0.1 to 12.31.127.25412.31.127.25532,766
6412.31.128.0/1712.31.128.1 to 12.31.255.25412.31.255.25532,766
6512.32.0.0/1712.32.0.1 to 12.32.127.25412.32.127.25532,766
6612.32.128.0/1712.32.128.1 to 12.32.255.25412.32.255.25532,766
6712.33.0.0/1712.33.0.1 to 12.33.127.25412.33.127.25532,766
6812.33.128.0/1712.33.128.1 to 12.33.255.25412.33.255.25532,766
6912.34.0.0/1712.34.0.1 to 12.34.127.25412.34.127.25532,766
7012.34.128.0/1712.34.128.1 to 12.34.255.25412.34.255.25532,766
7112.35.0.0/1712.35.0.1 to 12.35.127.25412.35.127.25532,766
7212.35.128.0/1712.35.128.1 to 12.35.255.25412.35.255.25532,766
7312.36.0.0/1712.36.0.1 to 12.36.127.25412.36.127.25532,766
7412.36.128.0/1712.36.128.1 to 12.36.255.25412.36.255.25532,766
7512.37.0.0/1712.37.0.1 to 12.37.127.25412.37.127.25532,766
7612.37.128.0/1712.37.128.1 to 12.37.255.25412.37.255.25532,766
7712.38.0.0/1712.38.0.1 to 12.38.127.25412.38.127.25532,766
7812.38.128.0/1712.38.128.1 to 12.38.255.25412.38.255.25532,766
7912.39.0.0/1712.39.0.1 to 12.39.127.25412.39.127.25532,766
8012.39.128.0/1712.39.128.1 to 12.39.255.25412.39.255.25532,766
8112.40.0.0/1712.40.0.1 to 12.40.127.25412.40.127.25532,766
8212.40.128.0/1712.40.128.1 to 12.40.255.25412.40.255.25532,766
8312.41.0.0/1712.41.0.1 to 12.41.127.25412.41.127.25532,766
8412.41.128.0/1712.41.128.1 to 12.41.255.25412.41.255.25532,766
8512.42.0.0/1712.42.0.1 to 12.42.127.25412.42.127.25532,766
8612.42.128.0/1712.42.128.1 to 12.42.255.25412.42.255.25532,766
8712.43.0.0/1712.43.0.1 to 12.43.127.25412.43.127.25532,766
8812.43.128.0/1712.43.128.1 to 12.43.255.25412.43.255.25532,766
8912.44.0.0/1712.44.0.1 to 12.44.127.25412.44.127.25532,766
9012.44.128.0/1712.44.128.1 to 12.44.255.25412.44.255.25532,766
9112.45.0.0/1712.45.0.1 to 12.45.127.25412.45.127.25532,766
9212.45.128.0/1712.45.128.1 to 12.45.255.25412.45.255.25532,766
9312.46.0.0/1712.46.0.1 to 12.46.127.25412.46.127.25532,766
9412.46.128.0/1712.46.128.1 to 12.46.255.25412.46.255.25532,766
9512.47.0.0/1712.47.0.1 to 12.47.127.25412.47.127.25532,766
9612.47.128.0/1712.47.128.1 to 12.47.255.25412.47.255.25532,766
9712.48.0.0/1712.48.0.1 to 12.48.127.25412.48.127.25532,766
9812.48.128.0/1712.48.128.1 to 12.48.255.25412.48.255.25532,766
9912.49.0.0/1712.49.0.1 to 12.49.127.25412.49.127.25532,766
10012.49.128.0/1712.49.128.1 to 12.49.255.25412.49.255.25532,766
10112.50.0.0/1712.50.0.1 to 12.50.127.25412.50.127.25532,766
10212.50.128.0/1712.50.128.1 to 12.50.255.25412.50.255.25532,766
10312.51.0.0/1712.51.0.1 to 12.51.127.25412.51.127.25532,766
10412.51.128.0/1712.51.128.1 to 12.51.255.25412.51.255.25532,766
10512.52.0.0/1712.52.0.1 to 12.52.127.25412.52.127.25532,766
10612.52.128.0/1712.52.128.1 to 12.52.255.25412.52.255.25532,766
10712.53.0.0/1712.53.0.1 to 12.53.127.25412.53.127.25532,766
10812.53.128.0/1712.53.128.1 to 12.53.255.25412.53.255.25532,766
10912.54.0.0/1712.54.0.1 to 12.54.127.25412.54.127.25532,766
11012.54.128.0/1712.54.128.1 to 12.54.255.25412.54.255.25532,766
11112.55.0.0/1712.55.0.1 to 12.55.127.25412.55.127.25532,766
11212.55.128.0/1712.55.128.1 to 12.55.255.25412.55.255.25532,766
11312.56.0.0/1712.56.0.1 to 12.56.127.25412.56.127.25532,766
11412.56.128.0/1712.56.128.1 to 12.56.255.25412.56.255.25532,766
11512.57.0.0/1712.57.0.1 to 12.57.127.25412.57.127.25532,766
11612.57.128.0/1712.57.128.1 to 12.57.255.25412.57.255.25532,766
11712.58.0.0/1712.58.0.1 to 12.58.127.25412.58.127.25532,766
11812.58.128.0/1712.58.128.1 to 12.58.255.25412.58.255.25532,766
11912.59.0.0/1712.59.0.1 to 12.59.127.25412.59.127.25532,766
12012.59.128.0/1712.59.128.1 to 12.59.255.25412.59.255.25532,766
12112.60.0.0/1712.60.0.1 to 12.60.127.25412.60.127.25532,766
12212.60.128.0/1712.60.128.1 to 12.60.255.25412.60.255.25532,766
12312.61.0.0/1712.61.0.1 to 12.61.127.25412.61.127.25532,766
12412.61.128.0/1712.61.128.1 to 12.61.255.25412.61.255.25532,766
12512.62.0.0/1712.62.0.1 to 12.62.127.25412.62.127.25532,766
12612.62.128.0/1712.62.128.1 to 12.62.255.25412.62.255.25532,766
12712.63.0.0/1712.63.0.1 to 12.63.127.25412.63.127.25532,766
12812.63.128.0/1712.63.128.1 to 12.63.255.25412.63.255.25532,766
12912.64.0.0/1712.64.0.1 to 12.64.127.25412.64.127.25532,766
13012.64.128.0/1712.64.128.1 to 12.64.255.25412.64.255.25532,766
13112.65.0.0/1712.65.0.1 to 12.65.127.25412.65.127.25532,766
13212.65.128.0/1712.65.128.1 to 12.65.255.25412.65.255.25532,766
13312.66.0.0/1712.66.0.1 to 12.66.127.25412.66.127.25532,766
13412.66.128.0/1712.66.128.1 to 12.66.255.25412.66.255.25532,766
13512.67.0.0/1712.67.0.1 to 12.67.127.25412.67.127.25532,766
13612.67.128.0/1712.67.128.1 to 12.67.255.25412.67.255.25532,766
13712.68.0.0/1712.68.0.1 to 12.68.127.25412.68.127.25532,766
13812.68.128.0/1712.68.128.1 to 12.68.255.25412.68.255.25532,766
13912.69.0.0/1712.69.0.1 to 12.69.127.25412.69.127.25532,766
14012.69.128.0/1712.69.128.1 to 12.69.255.25412.69.255.25532,766
14112.70.0.0/1712.70.0.1 to 12.70.127.25412.70.127.25532,766
14212.70.128.0/1712.70.128.1 to 12.70.255.25412.70.255.25532,766
14312.71.0.0/1712.71.0.1 to 12.71.127.25412.71.127.25532,766
14412.71.128.0/1712.71.128.1 to 12.71.255.25412.71.255.25532,766
14512.72.0.0/1712.72.0.1 to 12.72.127.25412.72.127.25532,766
14612.72.128.0/1712.72.128.1 to 12.72.255.25412.72.255.25532,766
14712.73.0.0/1712.73.0.1 to 12.73.127.25412.73.127.25532,766
14812.73.128.0/1712.73.128.1 to 12.73.255.25412.73.255.25532,766
14912.74.0.0/1712.74.0.1 to 12.74.127.25412.74.127.25532,766
15012.74.128.0/1712.74.128.1 to 12.74.255.25412.74.255.25532,766
15112.75.0.0/1712.75.0.1 to 12.75.127.25412.75.127.25532,766
15212.75.128.0/1712.75.128.1 to 12.75.255.25412.75.255.25532,766
15312.76.0.0/1712.76.0.1 to 12.76.127.25412.76.127.25532,766
15412.76.128.0/1712.76.128.1 to 12.76.255.25412.76.255.25532,766
15512.77.0.0/1712.77.0.1 to 12.77.127.25412.77.127.25532,766
15612.77.128.0/1712.77.128.1 to 12.77.255.25412.77.255.25532,766
15712.78.0.0/1712.78.0.1 to 12.78.127.25412.78.127.25532,766
15812.78.128.0/1712.78.128.1 to 12.78.255.25412.78.255.25532,766
15912.79.0.0/1712.79.0.1 to 12.79.127.25412.79.127.25532,766
16012.79.128.0/1712.79.128.1 to 12.79.255.25412.79.255.25532,766
16112.80.0.0/1712.80.0.1 to 12.80.127.25412.80.127.25532,766
16212.80.128.0/1712.80.128.1 to 12.80.255.25412.80.255.25532,766
16312.81.0.0/1712.81.0.1 to 12.81.127.25412.81.127.25532,766
16412.81.128.0/1712.81.128.1 to 12.81.255.25412.81.255.25532,766
16512.82.0.0/1712.82.0.1 to 12.82.127.25412.82.127.25532,766
16612.82.128.0/1712.82.128.1 to 12.82.255.25412.82.255.25532,766
16712.83.0.0/1712.83.0.1 to 12.83.127.25412.83.127.25532,766
16812.83.128.0/1712.83.128.1 to 12.83.255.25412.83.255.25532,766
16912.84.0.0/1712.84.0.1 to 12.84.127.25412.84.127.25532,766
17012.84.128.0/1712.84.128.1 to 12.84.255.25412.84.255.25532,766
17112.85.0.0/1712.85.0.1 to 12.85.127.25412.85.127.25532,766
17212.85.128.0/1712.85.128.1 to 12.85.255.25412.85.255.25532,766
17312.86.0.0/1712.86.0.1 to 12.86.127.25412.86.127.25532,766
17412.86.128.0/1712.86.128.1 to 12.86.255.25412.86.255.25532,766
17512.87.0.0/1712.87.0.1 to 12.87.127.25412.87.127.25532,766
17612.87.128.0/1712.87.128.1 to 12.87.255.25412.87.255.25532,766
17712.88.0.0/1712.88.0.1 to 12.88.127.25412.88.127.25532,766
17812.88.128.0/1712.88.128.1 to 12.88.255.25412.88.255.25532,766
17912.89.0.0/1712.89.0.1 to 12.89.127.25412.89.127.25532,766
18012.89.128.0/1712.89.128.1 to 12.89.255.25412.89.255.25532,766
18112.90.0.0/1712.90.0.1 to 12.90.127.25412.90.127.25532,766
18212.90.128.0/1712.90.128.1 to 12.90.255.25412.90.255.25532,766
18312.91.0.0/1712.91.0.1 to 12.91.127.25412.91.127.25532,766
18412.91.128.0/1712.91.128.1 to 12.91.255.25412.91.255.25532,766
18512.92.0.0/1712.92.0.1 to 12.92.127.25412.92.127.25532,766
18612.92.128.0/1712.92.128.1 to 12.92.255.25412.92.255.25532,766
18712.93.0.0/1712.93.0.1 to 12.93.127.25412.93.127.25532,766
18812.93.128.0/1712.93.128.1 to 12.93.255.25412.93.255.25532,766
18912.94.0.0/1712.94.0.1 to 12.94.127.25412.94.127.25532,766
19012.94.128.0/1712.94.128.1 to 12.94.255.25412.94.255.25532,766
19112.95.0.0/1712.95.0.1 to 12.95.127.25412.95.127.25532,766
19212.95.128.0/1712.95.128.1 to 12.95.255.25412.95.255.25532,766
19312.96.0.0/1712.96.0.1 to 12.96.127.25412.96.127.25532,766
19412.96.128.0/1712.96.128.1 to 12.96.255.25412.96.255.25532,766
19512.97.0.0/1712.97.0.1 to 12.97.127.25412.97.127.25532,766
19612.97.128.0/1712.97.128.1 to 12.97.255.25412.97.255.25532,766
19712.98.0.0/1712.98.0.1 to 12.98.127.25412.98.127.25532,766
19812.98.128.0/1712.98.128.1 to 12.98.255.25412.98.255.25532,766
19912.99.0.0/1712.99.0.1 to 12.99.127.25412.99.127.25532,766
20012.99.128.0/1712.99.128.1 to 12.99.255.25412.99.255.25532,766
20112.100.0.0/1712.100.0.1 to 12.100.127.25412.100.127.25532,766
20212.100.128.0/1712.100.128.1 to 12.100.255.25412.100.255.25532,766
20312.101.0.0/1712.101.0.1 to 12.101.127.25412.101.127.25532,766
20412.101.128.0/1712.101.128.1 to 12.101.255.25412.101.255.25532,766
20512.102.0.0/1712.102.0.1 to 12.102.127.25412.102.127.25532,766
20612.102.128.0/1712.102.128.1 to 12.102.255.25412.102.255.25532,766
20712.103.0.0/1712.103.0.1 to 12.103.127.25412.103.127.25532,766
20812.103.128.0/1712.103.128.1 to 12.103.255.25412.103.255.25532,766
20912.104.0.0/1712.104.0.1 to 12.104.127.25412.104.127.25532,766
21012.104.128.0/1712.104.128.1 to 12.104.255.25412.104.255.25532,766
21112.105.0.0/1712.105.0.1 to 12.105.127.25412.105.127.25532,766
21212.105.128.0/1712.105.128.1 to 12.105.255.25412.105.255.25532,766
21312.106.0.0/1712.106.0.1 to 12.106.127.25412.106.127.25532,766
21412.106.128.0/1712.106.128.1 to 12.106.255.25412.106.255.25532,766
21512.107.0.0/1712.107.0.1 to 12.107.127.25412.107.127.25532,766
21612.107.128.0/1712.107.128.1 to 12.107.255.25412.107.255.25532,766
21712.108.0.0/1712.108.0.1 to 12.108.127.25412.108.127.25532,766
21812.108.128.0/1712.108.128.1 to 12.108.255.25412.108.255.25532,766
21912.109.0.0/1712.109.0.1 to 12.109.127.25412.109.127.25532,766
22012.109.128.0/1712.109.128.1 to 12.109.255.25412.109.255.25532,766
22112.110.0.0/1712.110.0.1 to 12.110.127.25412.110.127.25532,766
22212.110.128.0/1712.110.128.1 to 12.110.255.25412.110.255.25532,766
22312.111.0.0/1712.111.0.1 to 12.111.127.25412.111.127.25532,766
22412.111.128.0/1712.111.128.1 to 12.111.255.25412.111.255.25532,766
22512.112.0.0/1712.112.0.1 to 12.112.127.25412.112.127.25532,766
22612.112.128.0/1712.112.128.1 to 12.112.255.25412.112.255.25532,766
22712.113.0.0/1712.113.0.1 to 12.113.127.25412.113.127.25532,766
22812.113.128.0/1712.113.128.1 to 12.113.255.25412.113.255.25532,766
22912.114.0.0/1712.114.0.1 to 12.114.127.25412.114.127.25532,766
23012.114.128.0/1712.114.128.1 to 12.114.255.25412.114.255.25532,766
23112.115.0.0/1712.115.0.1 to 12.115.127.25412.115.127.25532,766
23212.115.128.0/1712.115.128.1 to 12.115.255.25412.115.255.25532,766
23312.116.0.0/1712.116.0.1 to 12.116.127.25412.116.127.25532,766
23412.116.128.0/1712.116.128.1 to 12.116.255.25412.116.255.25532,766
23512.117.0.0/1712.117.0.1 to 12.117.127.25412.117.127.25532,766
23612.117.128.0/1712.117.128.1 to 12.117.255.25412.117.255.25532,766
23712.118.0.0/1712.118.0.1 to 12.118.127.25412.118.127.25532,766
23812.118.128.0/1712.118.128.1 to 12.118.255.25412.118.255.25532,766
23912.119.0.0/1712.119.0.1 to 12.119.127.25412.119.127.25532,766
24012.119.128.0/1712.119.128.1 to 12.119.255.25412.119.255.25532,766
24112.120.0.0/1712.120.0.1 to 12.120.127.25412.120.127.25532,766
24212.120.128.0/1712.120.128.1 to 12.120.255.25412.120.255.25532,766
24312.121.0.0/1712.121.0.1 to 12.121.127.25412.121.127.25532,766
24412.121.128.0/1712.121.128.1 to 12.121.255.25412.121.255.25532,766
24512.122.0.0/1712.122.0.1 to 12.122.127.25412.122.127.25532,766
24612.122.128.0/1712.122.128.1 to 12.122.255.25412.122.255.25532,766
24712.123.0.0/1712.123.0.1 to 12.123.127.25412.123.127.25532,766
24812.123.128.0/1712.123.128.1 to 12.123.255.25412.123.255.25532,766
24912.124.0.0/1712.124.0.1 to 12.124.127.25412.124.127.25532,766
25012.124.128.0/1712.124.128.1 to 12.124.255.25412.124.255.25532,766
25112.125.0.0/1712.125.0.1 to 12.125.127.25412.125.127.25532,766
25212.125.128.0/1712.125.128.1 to 12.125.255.25412.125.255.25532,766
25312.126.0.0/1712.126.0.1 to 12.126.127.25412.126.127.25532,766
25412.126.128.0/1712.126.128.1 to 12.126.255.25412.126.255.25532,766
25512.127.0.0/1712.127.0.1 to 12.127.127.25412.127.127.25532,766
25612.127.128.0/1712.127.128.1 to 12.127.255.25412.127.255.25532,766

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.