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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.

Network23.4.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
23.4.64.0
Broadcast address
23.4.127.255
First usable
23.4.64.1
Last usable
23.4.127.254
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 17044000 · Integer 386154496 to 386170879
Reverse DNS zones
64.4.23.in-addr.arpa
65.4.23.in-addr.arpa
66.4.23.in-addr.arpa
67.4.23.in-addr.arpa
68.4.23.in-addr.arpa
69.4.23.in-addr.arpa
70.4.23.in-addr.arpa
71.4.23.in-addr.arpa
72.4.23.in-addr.arpa
73.4.23.in-addr.arpa
74.4.23.in-addr.arpa
75.4.23.in-addr.arpa
76.4.23.in-addr.arpa
77.4.23.in-addr.arpa
78.4.23.in-addr.arpa
79.4.23.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
Address00010111.00000100.01000000.0000000023.4.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00010111.00000100.01000000.0000000023.4.64.0
Broadcast00010111.00000100.01111111.1111111123.4.127.255
Split into smaller subnets/29
/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)

23.4.64.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.4.64.0/2923.4.64.1 to 23.4.64.623.4.64.76
223.4.64.8/2923.4.64.9 to 23.4.64.1423.4.64.156
323.4.64.16/2923.4.64.17 to 23.4.64.2223.4.64.236
423.4.64.24/2923.4.64.25 to 23.4.64.3023.4.64.316
523.4.64.32/2923.4.64.33 to 23.4.64.3823.4.64.396
623.4.64.40/2923.4.64.41 to 23.4.64.4623.4.64.476
723.4.64.48/2923.4.64.49 to 23.4.64.5423.4.64.556
823.4.64.56/2923.4.64.57 to 23.4.64.6223.4.64.636
923.4.64.64/2923.4.64.65 to 23.4.64.7023.4.64.716
1023.4.64.72/2923.4.64.73 to 23.4.64.7823.4.64.796
1123.4.64.80/2923.4.64.81 to 23.4.64.8623.4.64.876
1223.4.64.88/2923.4.64.89 to 23.4.64.9423.4.64.956
1323.4.64.96/2923.4.64.97 to 23.4.64.10223.4.64.1036
1423.4.64.104/2923.4.64.105 to 23.4.64.11023.4.64.1116
1523.4.64.112/2923.4.64.113 to 23.4.64.11823.4.64.1196
1623.4.64.120/2923.4.64.121 to 23.4.64.12623.4.64.1276
1723.4.64.128/2923.4.64.129 to 23.4.64.13423.4.64.1356
1823.4.64.136/2923.4.64.137 to 23.4.64.14223.4.64.1436
1923.4.64.144/2923.4.64.145 to 23.4.64.15023.4.64.1516
2023.4.64.152/2923.4.64.153 to 23.4.64.15823.4.64.1596
2123.4.64.160/2923.4.64.161 to 23.4.64.16623.4.64.1676
2223.4.64.168/2923.4.64.169 to 23.4.64.17423.4.64.1756
2323.4.64.176/2923.4.64.177 to 23.4.64.18223.4.64.1836
2423.4.64.184/2923.4.64.185 to 23.4.64.19023.4.64.1916
2523.4.64.192/2923.4.64.193 to 23.4.64.19823.4.64.1996
2623.4.64.200/2923.4.64.201 to 23.4.64.20623.4.64.2076
2723.4.64.208/2923.4.64.209 to 23.4.64.21423.4.64.2156
2823.4.64.216/2923.4.64.217 to 23.4.64.22223.4.64.2236
2923.4.64.224/2923.4.64.225 to 23.4.64.23023.4.64.2316
3023.4.64.232/2923.4.64.233 to 23.4.64.23823.4.64.2396
3123.4.64.240/2923.4.64.241 to 23.4.64.24623.4.64.2476
3223.4.64.248/2923.4.64.249 to 23.4.64.25423.4.64.2556
3323.4.65.0/2923.4.65.1 to 23.4.65.623.4.65.76
3423.4.65.8/2923.4.65.9 to 23.4.65.1423.4.65.156
3523.4.65.16/2923.4.65.17 to 23.4.65.2223.4.65.236
3623.4.65.24/2923.4.65.25 to 23.4.65.3023.4.65.316
3723.4.65.32/2923.4.65.33 to 23.4.65.3823.4.65.396
3823.4.65.40/2923.4.65.41 to 23.4.65.4623.4.65.476
3923.4.65.48/2923.4.65.49 to 23.4.65.5423.4.65.556
4023.4.65.56/2923.4.65.57 to 23.4.65.6223.4.65.636
4123.4.65.64/2923.4.65.65 to 23.4.65.7023.4.65.716
4223.4.65.72/2923.4.65.73 to 23.4.65.7823.4.65.796
4323.4.65.80/2923.4.65.81 to 23.4.65.8623.4.65.876
4423.4.65.88/2923.4.65.89 to 23.4.65.9423.4.65.956
4523.4.65.96/2923.4.65.97 to 23.4.65.10223.4.65.1036
4623.4.65.104/2923.4.65.105 to 23.4.65.11023.4.65.1116
4723.4.65.112/2923.4.65.113 to 23.4.65.11823.4.65.1196
4823.4.65.120/2923.4.65.121 to 23.4.65.12623.4.65.1276
4923.4.65.128/2923.4.65.129 to 23.4.65.13423.4.65.1356
5023.4.65.136/2923.4.65.137 to 23.4.65.14223.4.65.1436
5123.4.65.144/2923.4.65.145 to 23.4.65.15023.4.65.1516
5223.4.65.152/2923.4.65.153 to 23.4.65.15823.4.65.1596
5323.4.65.160/2923.4.65.161 to 23.4.65.16623.4.65.1676
5423.4.65.168/2923.4.65.169 to 23.4.65.17423.4.65.1756
5523.4.65.176/2923.4.65.177 to 23.4.65.18223.4.65.1836
5623.4.65.184/2923.4.65.185 to 23.4.65.19023.4.65.1916
5723.4.65.192/2923.4.65.193 to 23.4.65.19823.4.65.1996
5823.4.65.200/2923.4.65.201 to 23.4.65.20623.4.65.2076
5923.4.65.208/2923.4.65.209 to 23.4.65.21423.4.65.2156
6023.4.65.216/2923.4.65.217 to 23.4.65.22223.4.65.2236
6123.4.65.224/2923.4.65.225 to 23.4.65.23023.4.65.2316
6223.4.65.232/2923.4.65.233 to 23.4.65.23823.4.65.2396
6323.4.65.240/2923.4.65.241 to 23.4.65.24623.4.65.2476
6423.4.65.248/2923.4.65.249 to 23.4.65.25423.4.65.2556
6523.4.66.0/2923.4.66.1 to 23.4.66.623.4.66.76
6623.4.66.8/2923.4.66.9 to 23.4.66.1423.4.66.156
6723.4.66.16/2923.4.66.17 to 23.4.66.2223.4.66.236
6823.4.66.24/2923.4.66.25 to 23.4.66.3023.4.66.316
6923.4.66.32/2923.4.66.33 to 23.4.66.3823.4.66.396
7023.4.66.40/2923.4.66.41 to 23.4.66.4623.4.66.476
7123.4.66.48/2923.4.66.49 to 23.4.66.5423.4.66.556
7223.4.66.56/2923.4.66.57 to 23.4.66.6223.4.66.636
7323.4.66.64/2923.4.66.65 to 23.4.66.7023.4.66.716
7423.4.66.72/2923.4.66.73 to 23.4.66.7823.4.66.796
7523.4.66.80/2923.4.66.81 to 23.4.66.8623.4.66.876
7623.4.66.88/2923.4.66.89 to 23.4.66.9423.4.66.956
7723.4.66.96/2923.4.66.97 to 23.4.66.10223.4.66.1036
7823.4.66.104/2923.4.66.105 to 23.4.66.11023.4.66.1116
7923.4.66.112/2923.4.66.113 to 23.4.66.11823.4.66.1196
8023.4.66.120/2923.4.66.121 to 23.4.66.12623.4.66.1276
8123.4.66.128/2923.4.66.129 to 23.4.66.13423.4.66.1356
8223.4.66.136/2923.4.66.137 to 23.4.66.14223.4.66.1436
8323.4.66.144/2923.4.66.145 to 23.4.66.15023.4.66.1516
8423.4.66.152/2923.4.66.153 to 23.4.66.15823.4.66.1596
8523.4.66.160/2923.4.66.161 to 23.4.66.16623.4.66.1676
8623.4.66.168/2923.4.66.169 to 23.4.66.17423.4.66.1756
8723.4.66.176/2923.4.66.177 to 23.4.66.18223.4.66.1836
8823.4.66.184/2923.4.66.185 to 23.4.66.19023.4.66.1916
8923.4.66.192/2923.4.66.193 to 23.4.66.19823.4.66.1996
9023.4.66.200/2923.4.66.201 to 23.4.66.20623.4.66.2076
9123.4.66.208/2923.4.66.209 to 23.4.66.21423.4.66.2156
9223.4.66.216/2923.4.66.217 to 23.4.66.22223.4.66.2236
9323.4.66.224/2923.4.66.225 to 23.4.66.23023.4.66.2316
9423.4.66.232/2923.4.66.233 to 23.4.66.23823.4.66.2396
9523.4.66.240/2923.4.66.241 to 23.4.66.24623.4.66.2476
9623.4.66.248/2923.4.66.249 to 23.4.66.25423.4.66.2556
9723.4.67.0/2923.4.67.1 to 23.4.67.623.4.67.76
9823.4.67.8/2923.4.67.9 to 23.4.67.1423.4.67.156
9923.4.67.16/2923.4.67.17 to 23.4.67.2223.4.67.236
10023.4.67.24/2923.4.67.25 to 23.4.67.3023.4.67.316
10123.4.67.32/2923.4.67.33 to 23.4.67.3823.4.67.396
10223.4.67.40/2923.4.67.41 to 23.4.67.4623.4.67.476
10323.4.67.48/2923.4.67.49 to 23.4.67.5423.4.67.556
10423.4.67.56/2923.4.67.57 to 23.4.67.6223.4.67.636
10523.4.67.64/2923.4.67.65 to 23.4.67.7023.4.67.716
10623.4.67.72/2923.4.67.73 to 23.4.67.7823.4.67.796
10723.4.67.80/2923.4.67.81 to 23.4.67.8623.4.67.876
10823.4.67.88/2923.4.67.89 to 23.4.67.9423.4.67.956
10923.4.67.96/2923.4.67.97 to 23.4.67.10223.4.67.1036
11023.4.67.104/2923.4.67.105 to 23.4.67.11023.4.67.1116
11123.4.67.112/2923.4.67.113 to 23.4.67.11823.4.67.1196
11223.4.67.120/2923.4.67.121 to 23.4.67.12623.4.67.1276
11323.4.67.128/2923.4.67.129 to 23.4.67.13423.4.67.1356
11423.4.67.136/2923.4.67.137 to 23.4.67.14223.4.67.1436
11523.4.67.144/2923.4.67.145 to 23.4.67.15023.4.67.1516
11623.4.67.152/2923.4.67.153 to 23.4.67.15823.4.67.1596
11723.4.67.160/2923.4.67.161 to 23.4.67.16623.4.67.1676
11823.4.67.168/2923.4.67.169 to 23.4.67.17423.4.67.1756
11923.4.67.176/2923.4.67.177 to 23.4.67.18223.4.67.1836
12023.4.67.184/2923.4.67.185 to 23.4.67.19023.4.67.1916
12123.4.67.192/2923.4.67.193 to 23.4.67.19823.4.67.1996
12223.4.67.200/2923.4.67.201 to 23.4.67.20623.4.67.2076
12323.4.67.208/2923.4.67.209 to 23.4.67.21423.4.67.2156
12423.4.67.216/2923.4.67.217 to 23.4.67.22223.4.67.2236
12523.4.67.224/2923.4.67.225 to 23.4.67.23023.4.67.2316
12623.4.67.232/2923.4.67.233 to 23.4.67.23823.4.67.2396
12723.4.67.240/2923.4.67.241 to 23.4.67.24623.4.67.2476
12823.4.67.248/2923.4.67.249 to 23.4.67.25423.4.67.2556
12923.4.68.0/2923.4.68.1 to 23.4.68.623.4.68.76
13023.4.68.8/2923.4.68.9 to 23.4.68.1423.4.68.156
13123.4.68.16/2923.4.68.17 to 23.4.68.2223.4.68.236
13223.4.68.24/2923.4.68.25 to 23.4.68.3023.4.68.316
13323.4.68.32/2923.4.68.33 to 23.4.68.3823.4.68.396
13423.4.68.40/2923.4.68.41 to 23.4.68.4623.4.68.476
13523.4.68.48/2923.4.68.49 to 23.4.68.5423.4.68.556
13623.4.68.56/2923.4.68.57 to 23.4.68.6223.4.68.636
13723.4.68.64/2923.4.68.65 to 23.4.68.7023.4.68.716
13823.4.68.72/2923.4.68.73 to 23.4.68.7823.4.68.796
13923.4.68.80/2923.4.68.81 to 23.4.68.8623.4.68.876
14023.4.68.88/2923.4.68.89 to 23.4.68.9423.4.68.956
14123.4.68.96/2923.4.68.97 to 23.4.68.10223.4.68.1036
14223.4.68.104/2923.4.68.105 to 23.4.68.11023.4.68.1116
14323.4.68.112/2923.4.68.113 to 23.4.68.11823.4.68.1196
14423.4.68.120/2923.4.68.121 to 23.4.68.12623.4.68.1276
14523.4.68.128/2923.4.68.129 to 23.4.68.13423.4.68.1356
14623.4.68.136/2923.4.68.137 to 23.4.68.14223.4.68.1436
14723.4.68.144/2923.4.68.145 to 23.4.68.15023.4.68.1516
14823.4.68.152/2923.4.68.153 to 23.4.68.15823.4.68.1596
14923.4.68.160/2923.4.68.161 to 23.4.68.16623.4.68.1676
15023.4.68.168/2923.4.68.169 to 23.4.68.17423.4.68.1756
15123.4.68.176/2923.4.68.177 to 23.4.68.18223.4.68.1836
15223.4.68.184/2923.4.68.185 to 23.4.68.19023.4.68.1916
15323.4.68.192/2923.4.68.193 to 23.4.68.19823.4.68.1996
15423.4.68.200/2923.4.68.201 to 23.4.68.20623.4.68.2076
15523.4.68.208/2923.4.68.209 to 23.4.68.21423.4.68.2156
15623.4.68.216/2923.4.68.217 to 23.4.68.22223.4.68.2236
15723.4.68.224/2923.4.68.225 to 23.4.68.23023.4.68.2316
15823.4.68.232/2923.4.68.233 to 23.4.68.23823.4.68.2396
15923.4.68.240/2923.4.68.241 to 23.4.68.24623.4.68.2476
16023.4.68.248/2923.4.68.249 to 23.4.68.25423.4.68.2556
16123.4.69.0/2923.4.69.1 to 23.4.69.623.4.69.76
16223.4.69.8/2923.4.69.9 to 23.4.69.1423.4.69.156
16323.4.69.16/2923.4.69.17 to 23.4.69.2223.4.69.236
16423.4.69.24/2923.4.69.25 to 23.4.69.3023.4.69.316
16523.4.69.32/2923.4.69.33 to 23.4.69.3823.4.69.396
16623.4.69.40/2923.4.69.41 to 23.4.69.4623.4.69.476
16723.4.69.48/2923.4.69.49 to 23.4.69.5423.4.69.556
16823.4.69.56/2923.4.69.57 to 23.4.69.6223.4.69.636
16923.4.69.64/2923.4.69.65 to 23.4.69.7023.4.69.716
17023.4.69.72/2923.4.69.73 to 23.4.69.7823.4.69.796
17123.4.69.80/2923.4.69.81 to 23.4.69.8623.4.69.876
17223.4.69.88/2923.4.69.89 to 23.4.69.9423.4.69.956
17323.4.69.96/2923.4.69.97 to 23.4.69.10223.4.69.1036
17423.4.69.104/2923.4.69.105 to 23.4.69.11023.4.69.1116
17523.4.69.112/2923.4.69.113 to 23.4.69.11823.4.69.1196
17623.4.69.120/2923.4.69.121 to 23.4.69.12623.4.69.1276
17723.4.69.128/2923.4.69.129 to 23.4.69.13423.4.69.1356
17823.4.69.136/2923.4.69.137 to 23.4.69.14223.4.69.1436
17923.4.69.144/2923.4.69.145 to 23.4.69.15023.4.69.1516
18023.4.69.152/2923.4.69.153 to 23.4.69.15823.4.69.1596
18123.4.69.160/2923.4.69.161 to 23.4.69.16623.4.69.1676
18223.4.69.168/2923.4.69.169 to 23.4.69.17423.4.69.1756
18323.4.69.176/2923.4.69.177 to 23.4.69.18223.4.69.1836
18423.4.69.184/2923.4.69.185 to 23.4.69.19023.4.69.1916
18523.4.69.192/2923.4.69.193 to 23.4.69.19823.4.69.1996
18623.4.69.200/2923.4.69.201 to 23.4.69.20623.4.69.2076
18723.4.69.208/2923.4.69.209 to 23.4.69.21423.4.69.2156
18823.4.69.216/2923.4.69.217 to 23.4.69.22223.4.69.2236
18923.4.69.224/2923.4.69.225 to 23.4.69.23023.4.69.2316
19023.4.69.232/2923.4.69.233 to 23.4.69.23823.4.69.2396
19123.4.69.240/2923.4.69.241 to 23.4.69.24623.4.69.2476
19223.4.69.248/2923.4.69.249 to 23.4.69.25423.4.69.2556
19323.4.70.0/2923.4.70.1 to 23.4.70.623.4.70.76
19423.4.70.8/2923.4.70.9 to 23.4.70.1423.4.70.156
19523.4.70.16/2923.4.70.17 to 23.4.70.2223.4.70.236
19623.4.70.24/2923.4.70.25 to 23.4.70.3023.4.70.316
19723.4.70.32/2923.4.70.33 to 23.4.70.3823.4.70.396
19823.4.70.40/2923.4.70.41 to 23.4.70.4623.4.70.476
19923.4.70.48/2923.4.70.49 to 23.4.70.5423.4.70.556
20023.4.70.56/2923.4.70.57 to 23.4.70.6223.4.70.636
20123.4.70.64/2923.4.70.65 to 23.4.70.7023.4.70.716
20223.4.70.72/2923.4.70.73 to 23.4.70.7823.4.70.796
20323.4.70.80/2923.4.70.81 to 23.4.70.8623.4.70.876
20423.4.70.88/2923.4.70.89 to 23.4.70.9423.4.70.956
20523.4.70.96/2923.4.70.97 to 23.4.70.10223.4.70.1036
20623.4.70.104/2923.4.70.105 to 23.4.70.11023.4.70.1116
20723.4.70.112/2923.4.70.113 to 23.4.70.11823.4.70.1196
20823.4.70.120/2923.4.70.121 to 23.4.70.12623.4.70.1276
20923.4.70.128/2923.4.70.129 to 23.4.70.13423.4.70.1356
21023.4.70.136/2923.4.70.137 to 23.4.70.14223.4.70.1436
21123.4.70.144/2923.4.70.145 to 23.4.70.15023.4.70.1516
21223.4.70.152/2923.4.70.153 to 23.4.70.15823.4.70.1596
21323.4.70.160/2923.4.70.161 to 23.4.70.16623.4.70.1676
21423.4.70.168/2923.4.70.169 to 23.4.70.17423.4.70.1756
21523.4.70.176/2923.4.70.177 to 23.4.70.18223.4.70.1836
21623.4.70.184/2923.4.70.185 to 23.4.70.19023.4.70.1916
21723.4.70.192/2923.4.70.193 to 23.4.70.19823.4.70.1996
21823.4.70.200/2923.4.70.201 to 23.4.70.20623.4.70.2076
21923.4.70.208/2923.4.70.209 to 23.4.70.21423.4.70.2156
22023.4.70.216/2923.4.70.217 to 23.4.70.22223.4.70.2236
22123.4.70.224/2923.4.70.225 to 23.4.70.23023.4.70.2316
22223.4.70.232/2923.4.70.233 to 23.4.70.23823.4.70.2396
22323.4.70.240/2923.4.70.241 to 23.4.70.24623.4.70.2476
22423.4.70.248/2923.4.70.249 to 23.4.70.25423.4.70.2556
22523.4.71.0/2923.4.71.1 to 23.4.71.623.4.71.76
22623.4.71.8/2923.4.71.9 to 23.4.71.1423.4.71.156
22723.4.71.16/2923.4.71.17 to 23.4.71.2223.4.71.236
22823.4.71.24/2923.4.71.25 to 23.4.71.3023.4.71.316
22923.4.71.32/2923.4.71.33 to 23.4.71.3823.4.71.396
23023.4.71.40/2923.4.71.41 to 23.4.71.4623.4.71.476
23123.4.71.48/2923.4.71.49 to 23.4.71.5423.4.71.556
23223.4.71.56/2923.4.71.57 to 23.4.71.6223.4.71.636
23323.4.71.64/2923.4.71.65 to 23.4.71.7023.4.71.716
23423.4.71.72/2923.4.71.73 to 23.4.71.7823.4.71.796
23523.4.71.80/2923.4.71.81 to 23.4.71.8623.4.71.876
23623.4.71.88/2923.4.71.89 to 23.4.71.9423.4.71.956
23723.4.71.96/2923.4.71.97 to 23.4.71.10223.4.71.1036
23823.4.71.104/2923.4.71.105 to 23.4.71.11023.4.71.1116
23923.4.71.112/2923.4.71.113 to 23.4.71.11823.4.71.1196
24023.4.71.120/2923.4.71.121 to 23.4.71.12623.4.71.1276
24123.4.71.128/2923.4.71.129 to 23.4.71.13423.4.71.1356
24223.4.71.136/2923.4.71.137 to 23.4.71.14223.4.71.1436
24323.4.71.144/2923.4.71.145 to 23.4.71.15023.4.71.1516
24423.4.71.152/2923.4.71.153 to 23.4.71.15823.4.71.1596
24523.4.71.160/2923.4.71.161 to 23.4.71.16623.4.71.1676
24623.4.71.168/2923.4.71.169 to 23.4.71.17423.4.71.1756
24723.4.71.176/2923.4.71.177 to 23.4.71.18223.4.71.1836
24823.4.71.184/2923.4.71.185 to 23.4.71.19023.4.71.1916
24923.4.71.192/2923.4.71.193 to 23.4.71.19823.4.71.1996
25023.4.71.200/2923.4.71.201 to 23.4.71.20623.4.71.2076
25123.4.71.208/2923.4.71.209 to 23.4.71.21423.4.71.2156
25223.4.71.216/2923.4.71.217 to 23.4.71.22223.4.71.2236
25323.4.71.224/2923.4.71.225 to 23.4.71.23023.4.71.2316
25423.4.71.232/2923.4.71.233 to 23.4.71.23823.4.71.2396
25523.4.71.240/2923.4.71.241 to 23.4.71.24623.4.71.2476
25623.4.71.248/2923.4.71.249 to 23.4.71.25423.4.71.2556

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.