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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.

Network23.2.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
23.2.64.0
Broadcast address
23.2.95.255
First usable
23.2.64.1
Last usable
23.2.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 17024000 · Integer 386023424 to 386031615
Reverse DNS zones
64.2.23.in-addr.arpa
65.2.23.in-addr.arpa
66.2.23.in-addr.arpa
67.2.23.in-addr.arpa
68.2.23.in-addr.arpa
69.2.23.in-addr.arpa
70.2.23.in-addr.arpa
71.2.23.in-addr.arpa
72.2.23.in-addr.arpa
73.2.23.in-addr.arpa
74.2.23.in-addr.arpa
75.2.23.in-addr.arpa
76.2.23.in-addr.arpa
77.2.23.in-addr.arpa
78.2.23.in-addr.arpa
79.2.23.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010111.00000010.01000000.0000000023.2.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network00010111.00000010.01000000.0000000023.2.64.0
Broadcast00010111.00000010.01011111.1111111123.2.95.255
Split into smaller subnets/28
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

23.2.64.0/19 makes 512 subnets of /28; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.2.64.0/2823.2.64.1 to 23.2.64.1423.2.64.1514
223.2.64.16/2823.2.64.17 to 23.2.64.3023.2.64.3114
323.2.64.32/2823.2.64.33 to 23.2.64.4623.2.64.4714
423.2.64.48/2823.2.64.49 to 23.2.64.6223.2.64.6314
523.2.64.64/2823.2.64.65 to 23.2.64.7823.2.64.7914
623.2.64.80/2823.2.64.81 to 23.2.64.9423.2.64.9514
723.2.64.96/2823.2.64.97 to 23.2.64.11023.2.64.11114
823.2.64.112/2823.2.64.113 to 23.2.64.12623.2.64.12714
923.2.64.128/2823.2.64.129 to 23.2.64.14223.2.64.14314
1023.2.64.144/2823.2.64.145 to 23.2.64.15823.2.64.15914
1123.2.64.160/2823.2.64.161 to 23.2.64.17423.2.64.17514
1223.2.64.176/2823.2.64.177 to 23.2.64.19023.2.64.19114
1323.2.64.192/2823.2.64.193 to 23.2.64.20623.2.64.20714
1423.2.64.208/2823.2.64.209 to 23.2.64.22223.2.64.22314
1523.2.64.224/2823.2.64.225 to 23.2.64.23823.2.64.23914
1623.2.64.240/2823.2.64.241 to 23.2.64.25423.2.64.25514
1723.2.65.0/2823.2.65.1 to 23.2.65.1423.2.65.1514
1823.2.65.16/2823.2.65.17 to 23.2.65.3023.2.65.3114
1923.2.65.32/2823.2.65.33 to 23.2.65.4623.2.65.4714
2023.2.65.48/2823.2.65.49 to 23.2.65.6223.2.65.6314
2123.2.65.64/2823.2.65.65 to 23.2.65.7823.2.65.7914
2223.2.65.80/2823.2.65.81 to 23.2.65.9423.2.65.9514
2323.2.65.96/2823.2.65.97 to 23.2.65.11023.2.65.11114
2423.2.65.112/2823.2.65.113 to 23.2.65.12623.2.65.12714
2523.2.65.128/2823.2.65.129 to 23.2.65.14223.2.65.14314
2623.2.65.144/2823.2.65.145 to 23.2.65.15823.2.65.15914
2723.2.65.160/2823.2.65.161 to 23.2.65.17423.2.65.17514
2823.2.65.176/2823.2.65.177 to 23.2.65.19023.2.65.19114
2923.2.65.192/2823.2.65.193 to 23.2.65.20623.2.65.20714
3023.2.65.208/2823.2.65.209 to 23.2.65.22223.2.65.22314
3123.2.65.224/2823.2.65.225 to 23.2.65.23823.2.65.23914
3223.2.65.240/2823.2.65.241 to 23.2.65.25423.2.65.25514
3323.2.66.0/2823.2.66.1 to 23.2.66.1423.2.66.1514
3423.2.66.16/2823.2.66.17 to 23.2.66.3023.2.66.3114
3523.2.66.32/2823.2.66.33 to 23.2.66.4623.2.66.4714
3623.2.66.48/2823.2.66.49 to 23.2.66.6223.2.66.6314
3723.2.66.64/2823.2.66.65 to 23.2.66.7823.2.66.7914
3823.2.66.80/2823.2.66.81 to 23.2.66.9423.2.66.9514
3923.2.66.96/2823.2.66.97 to 23.2.66.11023.2.66.11114
4023.2.66.112/2823.2.66.113 to 23.2.66.12623.2.66.12714
4123.2.66.128/2823.2.66.129 to 23.2.66.14223.2.66.14314
4223.2.66.144/2823.2.66.145 to 23.2.66.15823.2.66.15914
4323.2.66.160/2823.2.66.161 to 23.2.66.17423.2.66.17514
4423.2.66.176/2823.2.66.177 to 23.2.66.19023.2.66.19114
4523.2.66.192/2823.2.66.193 to 23.2.66.20623.2.66.20714
4623.2.66.208/2823.2.66.209 to 23.2.66.22223.2.66.22314
4723.2.66.224/2823.2.66.225 to 23.2.66.23823.2.66.23914
4823.2.66.240/2823.2.66.241 to 23.2.66.25423.2.66.25514
4923.2.67.0/2823.2.67.1 to 23.2.67.1423.2.67.1514
5023.2.67.16/2823.2.67.17 to 23.2.67.3023.2.67.3114
5123.2.67.32/2823.2.67.33 to 23.2.67.4623.2.67.4714
5223.2.67.48/2823.2.67.49 to 23.2.67.6223.2.67.6314
5323.2.67.64/2823.2.67.65 to 23.2.67.7823.2.67.7914
5423.2.67.80/2823.2.67.81 to 23.2.67.9423.2.67.9514
5523.2.67.96/2823.2.67.97 to 23.2.67.11023.2.67.11114
5623.2.67.112/2823.2.67.113 to 23.2.67.12623.2.67.12714
5723.2.67.128/2823.2.67.129 to 23.2.67.14223.2.67.14314
5823.2.67.144/2823.2.67.145 to 23.2.67.15823.2.67.15914
5923.2.67.160/2823.2.67.161 to 23.2.67.17423.2.67.17514
6023.2.67.176/2823.2.67.177 to 23.2.67.19023.2.67.19114
6123.2.67.192/2823.2.67.193 to 23.2.67.20623.2.67.20714
6223.2.67.208/2823.2.67.209 to 23.2.67.22223.2.67.22314
6323.2.67.224/2823.2.67.225 to 23.2.67.23823.2.67.23914
6423.2.67.240/2823.2.67.241 to 23.2.67.25423.2.67.25514
6523.2.68.0/2823.2.68.1 to 23.2.68.1423.2.68.1514
6623.2.68.16/2823.2.68.17 to 23.2.68.3023.2.68.3114
6723.2.68.32/2823.2.68.33 to 23.2.68.4623.2.68.4714
6823.2.68.48/2823.2.68.49 to 23.2.68.6223.2.68.6314
6923.2.68.64/2823.2.68.65 to 23.2.68.7823.2.68.7914
7023.2.68.80/2823.2.68.81 to 23.2.68.9423.2.68.9514
7123.2.68.96/2823.2.68.97 to 23.2.68.11023.2.68.11114
7223.2.68.112/2823.2.68.113 to 23.2.68.12623.2.68.12714
7323.2.68.128/2823.2.68.129 to 23.2.68.14223.2.68.14314
7423.2.68.144/2823.2.68.145 to 23.2.68.15823.2.68.15914
7523.2.68.160/2823.2.68.161 to 23.2.68.17423.2.68.17514
7623.2.68.176/2823.2.68.177 to 23.2.68.19023.2.68.19114
7723.2.68.192/2823.2.68.193 to 23.2.68.20623.2.68.20714
7823.2.68.208/2823.2.68.209 to 23.2.68.22223.2.68.22314
7923.2.68.224/2823.2.68.225 to 23.2.68.23823.2.68.23914
8023.2.68.240/2823.2.68.241 to 23.2.68.25423.2.68.25514
8123.2.69.0/2823.2.69.1 to 23.2.69.1423.2.69.1514
8223.2.69.16/2823.2.69.17 to 23.2.69.3023.2.69.3114
8323.2.69.32/2823.2.69.33 to 23.2.69.4623.2.69.4714
8423.2.69.48/2823.2.69.49 to 23.2.69.6223.2.69.6314
8523.2.69.64/2823.2.69.65 to 23.2.69.7823.2.69.7914
8623.2.69.80/2823.2.69.81 to 23.2.69.9423.2.69.9514
8723.2.69.96/2823.2.69.97 to 23.2.69.11023.2.69.11114
8823.2.69.112/2823.2.69.113 to 23.2.69.12623.2.69.12714
8923.2.69.128/2823.2.69.129 to 23.2.69.14223.2.69.14314
9023.2.69.144/2823.2.69.145 to 23.2.69.15823.2.69.15914
9123.2.69.160/2823.2.69.161 to 23.2.69.17423.2.69.17514
9223.2.69.176/2823.2.69.177 to 23.2.69.19023.2.69.19114
9323.2.69.192/2823.2.69.193 to 23.2.69.20623.2.69.20714
9423.2.69.208/2823.2.69.209 to 23.2.69.22223.2.69.22314
9523.2.69.224/2823.2.69.225 to 23.2.69.23823.2.69.23914
9623.2.69.240/2823.2.69.241 to 23.2.69.25423.2.69.25514
9723.2.70.0/2823.2.70.1 to 23.2.70.1423.2.70.1514
9823.2.70.16/2823.2.70.17 to 23.2.70.3023.2.70.3114
9923.2.70.32/2823.2.70.33 to 23.2.70.4623.2.70.4714
10023.2.70.48/2823.2.70.49 to 23.2.70.6223.2.70.6314
10123.2.70.64/2823.2.70.65 to 23.2.70.7823.2.70.7914
10223.2.70.80/2823.2.70.81 to 23.2.70.9423.2.70.9514
10323.2.70.96/2823.2.70.97 to 23.2.70.11023.2.70.11114
10423.2.70.112/2823.2.70.113 to 23.2.70.12623.2.70.12714
10523.2.70.128/2823.2.70.129 to 23.2.70.14223.2.70.14314
10623.2.70.144/2823.2.70.145 to 23.2.70.15823.2.70.15914
10723.2.70.160/2823.2.70.161 to 23.2.70.17423.2.70.17514
10823.2.70.176/2823.2.70.177 to 23.2.70.19023.2.70.19114
10923.2.70.192/2823.2.70.193 to 23.2.70.20623.2.70.20714
11023.2.70.208/2823.2.70.209 to 23.2.70.22223.2.70.22314
11123.2.70.224/2823.2.70.225 to 23.2.70.23823.2.70.23914
11223.2.70.240/2823.2.70.241 to 23.2.70.25423.2.70.25514
11323.2.71.0/2823.2.71.1 to 23.2.71.1423.2.71.1514
11423.2.71.16/2823.2.71.17 to 23.2.71.3023.2.71.3114
11523.2.71.32/2823.2.71.33 to 23.2.71.4623.2.71.4714
11623.2.71.48/2823.2.71.49 to 23.2.71.6223.2.71.6314
11723.2.71.64/2823.2.71.65 to 23.2.71.7823.2.71.7914
11823.2.71.80/2823.2.71.81 to 23.2.71.9423.2.71.9514
11923.2.71.96/2823.2.71.97 to 23.2.71.11023.2.71.11114
12023.2.71.112/2823.2.71.113 to 23.2.71.12623.2.71.12714
12123.2.71.128/2823.2.71.129 to 23.2.71.14223.2.71.14314
12223.2.71.144/2823.2.71.145 to 23.2.71.15823.2.71.15914
12323.2.71.160/2823.2.71.161 to 23.2.71.17423.2.71.17514
12423.2.71.176/2823.2.71.177 to 23.2.71.19023.2.71.19114
12523.2.71.192/2823.2.71.193 to 23.2.71.20623.2.71.20714
12623.2.71.208/2823.2.71.209 to 23.2.71.22223.2.71.22314
12723.2.71.224/2823.2.71.225 to 23.2.71.23823.2.71.23914
12823.2.71.240/2823.2.71.241 to 23.2.71.25423.2.71.25514
12923.2.72.0/2823.2.72.1 to 23.2.72.1423.2.72.1514
13023.2.72.16/2823.2.72.17 to 23.2.72.3023.2.72.3114
13123.2.72.32/2823.2.72.33 to 23.2.72.4623.2.72.4714
13223.2.72.48/2823.2.72.49 to 23.2.72.6223.2.72.6314
13323.2.72.64/2823.2.72.65 to 23.2.72.7823.2.72.7914
13423.2.72.80/2823.2.72.81 to 23.2.72.9423.2.72.9514
13523.2.72.96/2823.2.72.97 to 23.2.72.11023.2.72.11114
13623.2.72.112/2823.2.72.113 to 23.2.72.12623.2.72.12714
13723.2.72.128/2823.2.72.129 to 23.2.72.14223.2.72.14314
13823.2.72.144/2823.2.72.145 to 23.2.72.15823.2.72.15914
13923.2.72.160/2823.2.72.161 to 23.2.72.17423.2.72.17514
14023.2.72.176/2823.2.72.177 to 23.2.72.19023.2.72.19114
14123.2.72.192/2823.2.72.193 to 23.2.72.20623.2.72.20714
14223.2.72.208/2823.2.72.209 to 23.2.72.22223.2.72.22314
14323.2.72.224/2823.2.72.225 to 23.2.72.23823.2.72.23914
14423.2.72.240/2823.2.72.241 to 23.2.72.25423.2.72.25514
14523.2.73.0/2823.2.73.1 to 23.2.73.1423.2.73.1514
14623.2.73.16/2823.2.73.17 to 23.2.73.3023.2.73.3114
14723.2.73.32/2823.2.73.33 to 23.2.73.4623.2.73.4714
14823.2.73.48/2823.2.73.49 to 23.2.73.6223.2.73.6314
14923.2.73.64/2823.2.73.65 to 23.2.73.7823.2.73.7914
15023.2.73.80/2823.2.73.81 to 23.2.73.9423.2.73.9514
15123.2.73.96/2823.2.73.97 to 23.2.73.11023.2.73.11114
15223.2.73.112/2823.2.73.113 to 23.2.73.12623.2.73.12714
15323.2.73.128/2823.2.73.129 to 23.2.73.14223.2.73.14314
15423.2.73.144/2823.2.73.145 to 23.2.73.15823.2.73.15914
15523.2.73.160/2823.2.73.161 to 23.2.73.17423.2.73.17514
15623.2.73.176/2823.2.73.177 to 23.2.73.19023.2.73.19114
15723.2.73.192/2823.2.73.193 to 23.2.73.20623.2.73.20714
15823.2.73.208/2823.2.73.209 to 23.2.73.22223.2.73.22314
15923.2.73.224/2823.2.73.225 to 23.2.73.23823.2.73.23914
16023.2.73.240/2823.2.73.241 to 23.2.73.25423.2.73.25514
16123.2.74.0/2823.2.74.1 to 23.2.74.1423.2.74.1514
16223.2.74.16/2823.2.74.17 to 23.2.74.3023.2.74.3114
16323.2.74.32/2823.2.74.33 to 23.2.74.4623.2.74.4714
16423.2.74.48/2823.2.74.49 to 23.2.74.6223.2.74.6314
16523.2.74.64/2823.2.74.65 to 23.2.74.7823.2.74.7914
16623.2.74.80/2823.2.74.81 to 23.2.74.9423.2.74.9514
16723.2.74.96/2823.2.74.97 to 23.2.74.11023.2.74.11114
16823.2.74.112/2823.2.74.113 to 23.2.74.12623.2.74.12714
16923.2.74.128/2823.2.74.129 to 23.2.74.14223.2.74.14314
17023.2.74.144/2823.2.74.145 to 23.2.74.15823.2.74.15914
17123.2.74.160/2823.2.74.161 to 23.2.74.17423.2.74.17514
17223.2.74.176/2823.2.74.177 to 23.2.74.19023.2.74.19114
17323.2.74.192/2823.2.74.193 to 23.2.74.20623.2.74.20714
17423.2.74.208/2823.2.74.209 to 23.2.74.22223.2.74.22314
17523.2.74.224/2823.2.74.225 to 23.2.74.23823.2.74.23914
17623.2.74.240/2823.2.74.241 to 23.2.74.25423.2.74.25514
17723.2.75.0/2823.2.75.1 to 23.2.75.1423.2.75.1514
17823.2.75.16/2823.2.75.17 to 23.2.75.3023.2.75.3114
17923.2.75.32/2823.2.75.33 to 23.2.75.4623.2.75.4714
18023.2.75.48/2823.2.75.49 to 23.2.75.6223.2.75.6314
18123.2.75.64/2823.2.75.65 to 23.2.75.7823.2.75.7914
18223.2.75.80/2823.2.75.81 to 23.2.75.9423.2.75.9514
18323.2.75.96/2823.2.75.97 to 23.2.75.11023.2.75.11114
18423.2.75.112/2823.2.75.113 to 23.2.75.12623.2.75.12714
18523.2.75.128/2823.2.75.129 to 23.2.75.14223.2.75.14314
18623.2.75.144/2823.2.75.145 to 23.2.75.15823.2.75.15914
18723.2.75.160/2823.2.75.161 to 23.2.75.17423.2.75.17514
18823.2.75.176/2823.2.75.177 to 23.2.75.19023.2.75.19114
18923.2.75.192/2823.2.75.193 to 23.2.75.20623.2.75.20714
19023.2.75.208/2823.2.75.209 to 23.2.75.22223.2.75.22314
19123.2.75.224/2823.2.75.225 to 23.2.75.23823.2.75.23914
19223.2.75.240/2823.2.75.241 to 23.2.75.25423.2.75.25514
19323.2.76.0/2823.2.76.1 to 23.2.76.1423.2.76.1514
19423.2.76.16/2823.2.76.17 to 23.2.76.3023.2.76.3114
19523.2.76.32/2823.2.76.33 to 23.2.76.4623.2.76.4714
19623.2.76.48/2823.2.76.49 to 23.2.76.6223.2.76.6314
19723.2.76.64/2823.2.76.65 to 23.2.76.7823.2.76.7914
19823.2.76.80/2823.2.76.81 to 23.2.76.9423.2.76.9514
19923.2.76.96/2823.2.76.97 to 23.2.76.11023.2.76.11114
20023.2.76.112/2823.2.76.113 to 23.2.76.12623.2.76.12714
20123.2.76.128/2823.2.76.129 to 23.2.76.14223.2.76.14314
20223.2.76.144/2823.2.76.145 to 23.2.76.15823.2.76.15914
20323.2.76.160/2823.2.76.161 to 23.2.76.17423.2.76.17514
20423.2.76.176/2823.2.76.177 to 23.2.76.19023.2.76.19114
20523.2.76.192/2823.2.76.193 to 23.2.76.20623.2.76.20714
20623.2.76.208/2823.2.76.209 to 23.2.76.22223.2.76.22314
20723.2.76.224/2823.2.76.225 to 23.2.76.23823.2.76.23914
20823.2.76.240/2823.2.76.241 to 23.2.76.25423.2.76.25514
20923.2.77.0/2823.2.77.1 to 23.2.77.1423.2.77.1514
21023.2.77.16/2823.2.77.17 to 23.2.77.3023.2.77.3114
21123.2.77.32/2823.2.77.33 to 23.2.77.4623.2.77.4714
21223.2.77.48/2823.2.77.49 to 23.2.77.6223.2.77.6314
21323.2.77.64/2823.2.77.65 to 23.2.77.7823.2.77.7914
21423.2.77.80/2823.2.77.81 to 23.2.77.9423.2.77.9514
21523.2.77.96/2823.2.77.97 to 23.2.77.11023.2.77.11114
21623.2.77.112/2823.2.77.113 to 23.2.77.12623.2.77.12714
21723.2.77.128/2823.2.77.129 to 23.2.77.14223.2.77.14314
21823.2.77.144/2823.2.77.145 to 23.2.77.15823.2.77.15914
21923.2.77.160/2823.2.77.161 to 23.2.77.17423.2.77.17514
22023.2.77.176/2823.2.77.177 to 23.2.77.19023.2.77.19114
22123.2.77.192/2823.2.77.193 to 23.2.77.20623.2.77.20714
22223.2.77.208/2823.2.77.209 to 23.2.77.22223.2.77.22314
22323.2.77.224/2823.2.77.225 to 23.2.77.23823.2.77.23914
22423.2.77.240/2823.2.77.241 to 23.2.77.25423.2.77.25514
22523.2.78.0/2823.2.78.1 to 23.2.78.1423.2.78.1514
22623.2.78.16/2823.2.78.17 to 23.2.78.3023.2.78.3114
22723.2.78.32/2823.2.78.33 to 23.2.78.4623.2.78.4714
22823.2.78.48/2823.2.78.49 to 23.2.78.6223.2.78.6314
22923.2.78.64/2823.2.78.65 to 23.2.78.7823.2.78.7914
23023.2.78.80/2823.2.78.81 to 23.2.78.9423.2.78.9514
23123.2.78.96/2823.2.78.97 to 23.2.78.11023.2.78.11114
23223.2.78.112/2823.2.78.113 to 23.2.78.12623.2.78.12714
23323.2.78.128/2823.2.78.129 to 23.2.78.14223.2.78.14314
23423.2.78.144/2823.2.78.145 to 23.2.78.15823.2.78.15914
23523.2.78.160/2823.2.78.161 to 23.2.78.17423.2.78.17514
23623.2.78.176/2823.2.78.177 to 23.2.78.19023.2.78.19114
23723.2.78.192/2823.2.78.193 to 23.2.78.20623.2.78.20714
23823.2.78.208/2823.2.78.209 to 23.2.78.22223.2.78.22314
23923.2.78.224/2823.2.78.225 to 23.2.78.23823.2.78.23914
24023.2.78.240/2823.2.78.241 to 23.2.78.25423.2.78.25514
24123.2.79.0/2823.2.79.1 to 23.2.79.1423.2.79.1514
24223.2.79.16/2823.2.79.17 to 23.2.79.3023.2.79.3114
24323.2.79.32/2823.2.79.33 to 23.2.79.4623.2.79.4714
24423.2.79.48/2823.2.79.49 to 23.2.79.6223.2.79.6314
24523.2.79.64/2823.2.79.65 to 23.2.79.7823.2.79.7914
24623.2.79.80/2823.2.79.81 to 23.2.79.9423.2.79.9514
24723.2.79.96/2823.2.79.97 to 23.2.79.11023.2.79.11114
24823.2.79.112/2823.2.79.113 to 23.2.79.12623.2.79.12714
24923.2.79.128/2823.2.79.129 to 23.2.79.14223.2.79.14314
25023.2.79.144/2823.2.79.145 to 23.2.79.15823.2.79.15914
25123.2.79.160/2823.2.79.161 to 23.2.79.17423.2.79.17514
25223.2.79.176/2823.2.79.177 to 23.2.79.19023.2.79.19114
25323.2.79.192/2823.2.79.193 to 23.2.79.20623.2.79.20714
25423.2.79.208/2823.2.79.209 to 23.2.79.22223.2.79.22314
25523.2.79.224/2823.2.79.225 to 23.2.79.23823.2.79.23914
25623.2.79.240/2823.2.79.241 to 23.2.79.25423.2.79.25514

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.