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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.

Network12.2.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
12.2.64.0
Broadcast address
12.2.127.255
First usable
12.2.64.1
Last usable
12.2.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
A (default /8)
As numbers
Hex 0C024000 · Integer 201474048 to 201490431
Reverse DNS zones
64.2.12.in-addr.arpa
65.2.12.in-addr.arpa
66.2.12.in-addr.arpa
67.2.12.in-addr.arpa
68.2.12.in-addr.arpa
69.2.12.in-addr.arpa
70.2.12.in-addr.arpa
71.2.12.in-addr.arpa
72.2.12.in-addr.arpa
73.2.12.in-addr.arpa
74.2.12.in-addr.arpa
75.2.12.in-addr.arpa
76.2.12.in-addr.arpa
77.2.12.in-addr.arpa
78.2.12.in-addr.arpa
79.2.12.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001100.00000010.01000000.0000000012.2.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00001100.00000010.01000000.0000000012.2.64.0
Broadcast00001100.00000010.01111111.1111111112.2.127.255
Split into smaller subnets/26
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

12.2.64.0/18 makes 256 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
112.2.64.0/2612.2.64.1 to 12.2.64.6212.2.64.6362
212.2.64.64/2612.2.64.65 to 12.2.64.12612.2.64.12762
312.2.64.128/2612.2.64.129 to 12.2.64.19012.2.64.19162
412.2.64.192/2612.2.64.193 to 12.2.64.25412.2.64.25562
512.2.65.0/2612.2.65.1 to 12.2.65.6212.2.65.6362
612.2.65.64/2612.2.65.65 to 12.2.65.12612.2.65.12762
712.2.65.128/2612.2.65.129 to 12.2.65.19012.2.65.19162
812.2.65.192/2612.2.65.193 to 12.2.65.25412.2.65.25562
912.2.66.0/2612.2.66.1 to 12.2.66.6212.2.66.6362
1012.2.66.64/2612.2.66.65 to 12.2.66.12612.2.66.12762
1112.2.66.128/2612.2.66.129 to 12.2.66.19012.2.66.19162
1212.2.66.192/2612.2.66.193 to 12.2.66.25412.2.66.25562
1312.2.67.0/2612.2.67.1 to 12.2.67.6212.2.67.6362
1412.2.67.64/2612.2.67.65 to 12.2.67.12612.2.67.12762
1512.2.67.128/2612.2.67.129 to 12.2.67.19012.2.67.19162
1612.2.67.192/2612.2.67.193 to 12.2.67.25412.2.67.25562
1712.2.68.0/2612.2.68.1 to 12.2.68.6212.2.68.6362
1812.2.68.64/2612.2.68.65 to 12.2.68.12612.2.68.12762
1912.2.68.128/2612.2.68.129 to 12.2.68.19012.2.68.19162
2012.2.68.192/2612.2.68.193 to 12.2.68.25412.2.68.25562
2112.2.69.0/2612.2.69.1 to 12.2.69.6212.2.69.6362
2212.2.69.64/2612.2.69.65 to 12.2.69.12612.2.69.12762
2312.2.69.128/2612.2.69.129 to 12.2.69.19012.2.69.19162
2412.2.69.192/2612.2.69.193 to 12.2.69.25412.2.69.25562
2512.2.70.0/2612.2.70.1 to 12.2.70.6212.2.70.6362
2612.2.70.64/2612.2.70.65 to 12.2.70.12612.2.70.12762
2712.2.70.128/2612.2.70.129 to 12.2.70.19012.2.70.19162
2812.2.70.192/2612.2.70.193 to 12.2.70.25412.2.70.25562
2912.2.71.0/2612.2.71.1 to 12.2.71.6212.2.71.6362
3012.2.71.64/2612.2.71.65 to 12.2.71.12612.2.71.12762
3112.2.71.128/2612.2.71.129 to 12.2.71.19012.2.71.19162
3212.2.71.192/2612.2.71.193 to 12.2.71.25412.2.71.25562
3312.2.72.0/2612.2.72.1 to 12.2.72.6212.2.72.6362
3412.2.72.64/2612.2.72.65 to 12.2.72.12612.2.72.12762
3512.2.72.128/2612.2.72.129 to 12.2.72.19012.2.72.19162
3612.2.72.192/2612.2.72.193 to 12.2.72.25412.2.72.25562
3712.2.73.0/2612.2.73.1 to 12.2.73.6212.2.73.6362
3812.2.73.64/2612.2.73.65 to 12.2.73.12612.2.73.12762
3912.2.73.128/2612.2.73.129 to 12.2.73.19012.2.73.19162
4012.2.73.192/2612.2.73.193 to 12.2.73.25412.2.73.25562
4112.2.74.0/2612.2.74.1 to 12.2.74.6212.2.74.6362
4212.2.74.64/2612.2.74.65 to 12.2.74.12612.2.74.12762
4312.2.74.128/2612.2.74.129 to 12.2.74.19012.2.74.19162
4412.2.74.192/2612.2.74.193 to 12.2.74.25412.2.74.25562
4512.2.75.0/2612.2.75.1 to 12.2.75.6212.2.75.6362
4612.2.75.64/2612.2.75.65 to 12.2.75.12612.2.75.12762
4712.2.75.128/2612.2.75.129 to 12.2.75.19012.2.75.19162
4812.2.75.192/2612.2.75.193 to 12.2.75.25412.2.75.25562
4912.2.76.0/2612.2.76.1 to 12.2.76.6212.2.76.6362
5012.2.76.64/2612.2.76.65 to 12.2.76.12612.2.76.12762
5112.2.76.128/2612.2.76.129 to 12.2.76.19012.2.76.19162
5212.2.76.192/2612.2.76.193 to 12.2.76.25412.2.76.25562
5312.2.77.0/2612.2.77.1 to 12.2.77.6212.2.77.6362
5412.2.77.64/2612.2.77.65 to 12.2.77.12612.2.77.12762
5512.2.77.128/2612.2.77.129 to 12.2.77.19012.2.77.19162
5612.2.77.192/2612.2.77.193 to 12.2.77.25412.2.77.25562
5712.2.78.0/2612.2.78.1 to 12.2.78.6212.2.78.6362
5812.2.78.64/2612.2.78.65 to 12.2.78.12612.2.78.12762
5912.2.78.128/2612.2.78.129 to 12.2.78.19012.2.78.19162
6012.2.78.192/2612.2.78.193 to 12.2.78.25412.2.78.25562
6112.2.79.0/2612.2.79.1 to 12.2.79.6212.2.79.6362
6212.2.79.64/2612.2.79.65 to 12.2.79.12612.2.79.12762
6312.2.79.128/2612.2.79.129 to 12.2.79.19012.2.79.19162
6412.2.79.192/2612.2.79.193 to 12.2.79.25412.2.79.25562
6512.2.80.0/2612.2.80.1 to 12.2.80.6212.2.80.6362
6612.2.80.64/2612.2.80.65 to 12.2.80.12612.2.80.12762
6712.2.80.128/2612.2.80.129 to 12.2.80.19012.2.80.19162
6812.2.80.192/2612.2.80.193 to 12.2.80.25412.2.80.25562
6912.2.81.0/2612.2.81.1 to 12.2.81.6212.2.81.6362
7012.2.81.64/2612.2.81.65 to 12.2.81.12612.2.81.12762
7112.2.81.128/2612.2.81.129 to 12.2.81.19012.2.81.19162
7212.2.81.192/2612.2.81.193 to 12.2.81.25412.2.81.25562
7312.2.82.0/2612.2.82.1 to 12.2.82.6212.2.82.6362
7412.2.82.64/2612.2.82.65 to 12.2.82.12612.2.82.12762
7512.2.82.128/2612.2.82.129 to 12.2.82.19012.2.82.19162
7612.2.82.192/2612.2.82.193 to 12.2.82.25412.2.82.25562
7712.2.83.0/2612.2.83.1 to 12.2.83.6212.2.83.6362
7812.2.83.64/2612.2.83.65 to 12.2.83.12612.2.83.12762
7912.2.83.128/2612.2.83.129 to 12.2.83.19012.2.83.19162
8012.2.83.192/2612.2.83.193 to 12.2.83.25412.2.83.25562
8112.2.84.0/2612.2.84.1 to 12.2.84.6212.2.84.6362
8212.2.84.64/2612.2.84.65 to 12.2.84.12612.2.84.12762
8312.2.84.128/2612.2.84.129 to 12.2.84.19012.2.84.19162
8412.2.84.192/2612.2.84.193 to 12.2.84.25412.2.84.25562
8512.2.85.0/2612.2.85.1 to 12.2.85.6212.2.85.6362
8612.2.85.64/2612.2.85.65 to 12.2.85.12612.2.85.12762
8712.2.85.128/2612.2.85.129 to 12.2.85.19012.2.85.19162
8812.2.85.192/2612.2.85.193 to 12.2.85.25412.2.85.25562
8912.2.86.0/2612.2.86.1 to 12.2.86.6212.2.86.6362
9012.2.86.64/2612.2.86.65 to 12.2.86.12612.2.86.12762
9112.2.86.128/2612.2.86.129 to 12.2.86.19012.2.86.19162
9212.2.86.192/2612.2.86.193 to 12.2.86.25412.2.86.25562
9312.2.87.0/2612.2.87.1 to 12.2.87.6212.2.87.6362
9412.2.87.64/2612.2.87.65 to 12.2.87.12612.2.87.12762
9512.2.87.128/2612.2.87.129 to 12.2.87.19012.2.87.19162
9612.2.87.192/2612.2.87.193 to 12.2.87.25412.2.87.25562
9712.2.88.0/2612.2.88.1 to 12.2.88.6212.2.88.6362
9812.2.88.64/2612.2.88.65 to 12.2.88.12612.2.88.12762
9912.2.88.128/2612.2.88.129 to 12.2.88.19012.2.88.19162
10012.2.88.192/2612.2.88.193 to 12.2.88.25412.2.88.25562
10112.2.89.0/2612.2.89.1 to 12.2.89.6212.2.89.6362
10212.2.89.64/2612.2.89.65 to 12.2.89.12612.2.89.12762
10312.2.89.128/2612.2.89.129 to 12.2.89.19012.2.89.19162
10412.2.89.192/2612.2.89.193 to 12.2.89.25412.2.89.25562
10512.2.90.0/2612.2.90.1 to 12.2.90.6212.2.90.6362
10612.2.90.64/2612.2.90.65 to 12.2.90.12612.2.90.12762
10712.2.90.128/2612.2.90.129 to 12.2.90.19012.2.90.19162
10812.2.90.192/2612.2.90.193 to 12.2.90.25412.2.90.25562
10912.2.91.0/2612.2.91.1 to 12.2.91.6212.2.91.6362
11012.2.91.64/2612.2.91.65 to 12.2.91.12612.2.91.12762
11112.2.91.128/2612.2.91.129 to 12.2.91.19012.2.91.19162
11212.2.91.192/2612.2.91.193 to 12.2.91.25412.2.91.25562
11312.2.92.0/2612.2.92.1 to 12.2.92.6212.2.92.6362
11412.2.92.64/2612.2.92.65 to 12.2.92.12612.2.92.12762
11512.2.92.128/2612.2.92.129 to 12.2.92.19012.2.92.19162
11612.2.92.192/2612.2.92.193 to 12.2.92.25412.2.92.25562
11712.2.93.0/2612.2.93.1 to 12.2.93.6212.2.93.6362
11812.2.93.64/2612.2.93.65 to 12.2.93.12612.2.93.12762
11912.2.93.128/2612.2.93.129 to 12.2.93.19012.2.93.19162
12012.2.93.192/2612.2.93.193 to 12.2.93.25412.2.93.25562
12112.2.94.0/2612.2.94.1 to 12.2.94.6212.2.94.6362
12212.2.94.64/2612.2.94.65 to 12.2.94.12612.2.94.12762
12312.2.94.128/2612.2.94.129 to 12.2.94.19012.2.94.19162
12412.2.94.192/2612.2.94.193 to 12.2.94.25412.2.94.25562
12512.2.95.0/2612.2.95.1 to 12.2.95.6212.2.95.6362
12612.2.95.64/2612.2.95.65 to 12.2.95.12612.2.95.12762
12712.2.95.128/2612.2.95.129 to 12.2.95.19012.2.95.19162
12812.2.95.192/2612.2.95.193 to 12.2.95.25412.2.95.25562
12912.2.96.0/2612.2.96.1 to 12.2.96.6212.2.96.6362
13012.2.96.64/2612.2.96.65 to 12.2.96.12612.2.96.12762
13112.2.96.128/2612.2.96.129 to 12.2.96.19012.2.96.19162
13212.2.96.192/2612.2.96.193 to 12.2.96.25412.2.96.25562
13312.2.97.0/2612.2.97.1 to 12.2.97.6212.2.97.6362
13412.2.97.64/2612.2.97.65 to 12.2.97.12612.2.97.12762
13512.2.97.128/2612.2.97.129 to 12.2.97.19012.2.97.19162
13612.2.97.192/2612.2.97.193 to 12.2.97.25412.2.97.25562
13712.2.98.0/2612.2.98.1 to 12.2.98.6212.2.98.6362
13812.2.98.64/2612.2.98.65 to 12.2.98.12612.2.98.12762
13912.2.98.128/2612.2.98.129 to 12.2.98.19012.2.98.19162
14012.2.98.192/2612.2.98.193 to 12.2.98.25412.2.98.25562
14112.2.99.0/2612.2.99.1 to 12.2.99.6212.2.99.6362
14212.2.99.64/2612.2.99.65 to 12.2.99.12612.2.99.12762
14312.2.99.128/2612.2.99.129 to 12.2.99.19012.2.99.19162
14412.2.99.192/2612.2.99.193 to 12.2.99.25412.2.99.25562
14512.2.100.0/2612.2.100.1 to 12.2.100.6212.2.100.6362
14612.2.100.64/2612.2.100.65 to 12.2.100.12612.2.100.12762
14712.2.100.128/2612.2.100.129 to 12.2.100.19012.2.100.19162
14812.2.100.192/2612.2.100.193 to 12.2.100.25412.2.100.25562
14912.2.101.0/2612.2.101.1 to 12.2.101.6212.2.101.6362
15012.2.101.64/2612.2.101.65 to 12.2.101.12612.2.101.12762
15112.2.101.128/2612.2.101.129 to 12.2.101.19012.2.101.19162
15212.2.101.192/2612.2.101.193 to 12.2.101.25412.2.101.25562
15312.2.102.0/2612.2.102.1 to 12.2.102.6212.2.102.6362
15412.2.102.64/2612.2.102.65 to 12.2.102.12612.2.102.12762
15512.2.102.128/2612.2.102.129 to 12.2.102.19012.2.102.19162
15612.2.102.192/2612.2.102.193 to 12.2.102.25412.2.102.25562
15712.2.103.0/2612.2.103.1 to 12.2.103.6212.2.103.6362
15812.2.103.64/2612.2.103.65 to 12.2.103.12612.2.103.12762
15912.2.103.128/2612.2.103.129 to 12.2.103.19012.2.103.19162
16012.2.103.192/2612.2.103.193 to 12.2.103.25412.2.103.25562
16112.2.104.0/2612.2.104.1 to 12.2.104.6212.2.104.6362
16212.2.104.64/2612.2.104.65 to 12.2.104.12612.2.104.12762
16312.2.104.128/2612.2.104.129 to 12.2.104.19012.2.104.19162
16412.2.104.192/2612.2.104.193 to 12.2.104.25412.2.104.25562
16512.2.105.0/2612.2.105.1 to 12.2.105.6212.2.105.6362
16612.2.105.64/2612.2.105.65 to 12.2.105.12612.2.105.12762
16712.2.105.128/2612.2.105.129 to 12.2.105.19012.2.105.19162
16812.2.105.192/2612.2.105.193 to 12.2.105.25412.2.105.25562
16912.2.106.0/2612.2.106.1 to 12.2.106.6212.2.106.6362
17012.2.106.64/2612.2.106.65 to 12.2.106.12612.2.106.12762
17112.2.106.128/2612.2.106.129 to 12.2.106.19012.2.106.19162
17212.2.106.192/2612.2.106.193 to 12.2.106.25412.2.106.25562
17312.2.107.0/2612.2.107.1 to 12.2.107.6212.2.107.6362
17412.2.107.64/2612.2.107.65 to 12.2.107.12612.2.107.12762
17512.2.107.128/2612.2.107.129 to 12.2.107.19012.2.107.19162
17612.2.107.192/2612.2.107.193 to 12.2.107.25412.2.107.25562
17712.2.108.0/2612.2.108.1 to 12.2.108.6212.2.108.6362
17812.2.108.64/2612.2.108.65 to 12.2.108.12612.2.108.12762
17912.2.108.128/2612.2.108.129 to 12.2.108.19012.2.108.19162
18012.2.108.192/2612.2.108.193 to 12.2.108.25412.2.108.25562
18112.2.109.0/2612.2.109.1 to 12.2.109.6212.2.109.6362
18212.2.109.64/2612.2.109.65 to 12.2.109.12612.2.109.12762
18312.2.109.128/2612.2.109.129 to 12.2.109.19012.2.109.19162
18412.2.109.192/2612.2.109.193 to 12.2.109.25412.2.109.25562
18512.2.110.0/2612.2.110.1 to 12.2.110.6212.2.110.6362
18612.2.110.64/2612.2.110.65 to 12.2.110.12612.2.110.12762
18712.2.110.128/2612.2.110.129 to 12.2.110.19012.2.110.19162
18812.2.110.192/2612.2.110.193 to 12.2.110.25412.2.110.25562
18912.2.111.0/2612.2.111.1 to 12.2.111.6212.2.111.6362
19012.2.111.64/2612.2.111.65 to 12.2.111.12612.2.111.12762
19112.2.111.128/2612.2.111.129 to 12.2.111.19012.2.111.19162
19212.2.111.192/2612.2.111.193 to 12.2.111.25412.2.111.25562
19312.2.112.0/2612.2.112.1 to 12.2.112.6212.2.112.6362
19412.2.112.64/2612.2.112.65 to 12.2.112.12612.2.112.12762
19512.2.112.128/2612.2.112.129 to 12.2.112.19012.2.112.19162
19612.2.112.192/2612.2.112.193 to 12.2.112.25412.2.112.25562
19712.2.113.0/2612.2.113.1 to 12.2.113.6212.2.113.6362
19812.2.113.64/2612.2.113.65 to 12.2.113.12612.2.113.12762
19912.2.113.128/2612.2.113.129 to 12.2.113.19012.2.113.19162
20012.2.113.192/2612.2.113.193 to 12.2.113.25412.2.113.25562
20112.2.114.0/2612.2.114.1 to 12.2.114.6212.2.114.6362
20212.2.114.64/2612.2.114.65 to 12.2.114.12612.2.114.12762
20312.2.114.128/2612.2.114.129 to 12.2.114.19012.2.114.19162
20412.2.114.192/2612.2.114.193 to 12.2.114.25412.2.114.25562
20512.2.115.0/2612.2.115.1 to 12.2.115.6212.2.115.6362
20612.2.115.64/2612.2.115.65 to 12.2.115.12612.2.115.12762
20712.2.115.128/2612.2.115.129 to 12.2.115.19012.2.115.19162
20812.2.115.192/2612.2.115.193 to 12.2.115.25412.2.115.25562
20912.2.116.0/2612.2.116.1 to 12.2.116.6212.2.116.6362
21012.2.116.64/2612.2.116.65 to 12.2.116.12612.2.116.12762
21112.2.116.128/2612.2.116.129 to 12.2.116.19012.2.116.19162
21212.2.116.192/2612.2.116.193 to 12.2.116.25412.2.116.25562
21312.2.117.0/2612.2.117.1 to 12.2.117.6212.2.117.6362
21412.2.117.64/2612.2.117.65 to 12.2.117.12612.2.117.12762
21512.2.117.128/2612.2.117.129 to 12.2.117.19012.2.117.19162
21612.2.117.192/2612.2.117.193 to 12.2.117.25412.2.117.25562
21712.2.118.0/2612.2.118.1 to 12.2.118.6212.2.118.6362
21812.2.118.64/2612.2.118.65 to 12.2.118.12612.2.118.12762
21912.2.118.128/2612.2.118.129 to 12.2.118.19012.2.118.19162
22012.2.118.192/2612.2.118.193 to 12.2.118.25412.2.118.25562
22112.2.119.0/2612.2.119.1 to 12.2.119.6212.2.119.6362
22212.2.119.64/2612.2.119.65 to 12.2.119.12612.2.119.12762
22312.2.119.128/2612.2.119.129 to 12.2.119.19012.2.119.19162
22412.2.119.192/2612.2.119.193 to 12.2.119.25412.2.119.25562
22512.2.120.0/2612.2.120.1 to 12.2.120.6212.2.120.6362
22612.2.120.64/2612.2.120.65 to 12.2.120.12612.2.120.12762
22712.2.120.128/2612.2.120.129 to 12.2.120.19012.2.120.19162
22812.2.120.192/2612.2.120.193 to 12.2.120.25412.2.120.25562
22912.2.121.0/2612.2.121.1 to 12.2.121.6212.2.121.6362
23012.2.121.64/2612.2.121.65 to 12.2.121.12612.2.121.12762
23112.2.121.128/2612.2.121.129 to 12.2.121.19012.2.121.19162
23212.2.121.192/2612.2.121.193 to 12.2.121.25412.2.121.25562
23312.2.122.0/2612.2.122.1 to 12.2.122.6212.2.122.6362
23412.2.122.64/2612.2.122.65 to 12.2.122.12612.2.122.12762
23512.2.122.128/2612.2.122.129 to 12.2.122.19012.2.122.19162
23612.2.122.192/2612.2.122.193 to 12.2.122.25412.2.122.25562
23712.2.123.0/2612.2.123.1 to 12.2.123.6212.2.123.6362
23812.2.123.64/2612.2.123.65 to 12.2.123.12612.2.123.12762
23912.2.123.128/2612.2.123.129 to 12.2.123.19012.2.123.19162
24012.2.123.192/2612.2.123.193 to 12.2.123.25412.2.123.25562
24112.2.124.0/2612.2.124.1 to 12.2.124.6212.2.124.6362
24212.2.124.64/2612.2.124.65 to 12.2.124.12612.2.124.12762
24312.2.124.128/2612.2.124.129 to 12.2.124.19012.2.124.19162
24412.2.124.192/2612.2.124.193 to 12.2.124.25412.2.124.25562
24512.2.125.0/2612.2.125.1 to 12.2.125.6212.2.125.6362
24612.2.125.64/2612.2.125.65 to 12.2.125.12612.2.125.12762
24712.2.125.128/2612.2.125.129 to 12.2.125.19012.2.125.19162
24812.2.125.192/2612.2.125.193 to 12.2.125.25412.2.125.25562
24912.2.126.0/2612.2.126.1 to 12.2.126.6212.2.126.6362
25012.2.126.64/2612.2.126.65 to 12.2.126.12612.2.126.12762
25112.2.126.128/2612.2.126.129 to 12.2.126.19012.2.126.19162
25212.2.126.192/2612.2.126.193 to 12.2.126.25412.2.126.25562
25312.2.127.0/2612.2.127.1 to 12.2.127.6212.2.127.6362
25412.2.127.64/2612.2.127.65 to 12.2.127.12612.2.127.12762
25512.2.127.128/2612.2.127.129 to 12.2.127.19012.2.127.19162
25612.2.127.192/2612.2.127.193 to 12.2.127.25412.2.127.25562

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.