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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.

Network25.85.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
25.85.0.0
Broadcast address
25.85.127.255
First usable
25.85.0.1
Last usable
25.85.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
A (default /8)
As numbers
Hex 19550000 · Integer 425000960 to 425033727
Reverse DNS zones
0.85.25.in-addr.arpa
1.85.25.in-addr.arpa
2.85.25.in-addr.arpa
3.85.25.in-addr.arpa
4.85.25.in-addr.arpa
5.85.25.in-addr.arpa
6.85.25.in-addr.arpa
7.85.25.in-addr.arpa
8.85.25.in-addr.arpa
9.85.25.in-addr.arpa
10.85.25.in-addr.arpa
11.85.25.in-addr.arpa
12.85.25.in-addr.arpa
13.85.25.in-addr.arpa
14.85.25.in-addr.arpa
15.85.25.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011001.01010101.00000000.0000000025.85.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network00011001.01010101.00000000.0000000025.85.0.0
Broadcast00011001.01010101.01111111.1111111125.85.127.255
Split into smaller subnets/27
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

25.85.0.0/17 makes 1,024 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.85.0.0/2725.85.0.1 to 25.85.0.3025.85.0.3130
225.85.0.32/2725.85.0.33 to 25.85.0.6225.85.0.6330
325.85.0.64/2725.85.0.65 to 25.85.0.9425.85.0.9530
425.85.0.96/2725.85.0.97 to 25.85.0.12625.85.0.12730
525.85.0.128/2725.85.0.129 to 25.85.0.15825.85.0.15930
625.85.0.160/2725.85.0.161 to 25.85.0.19025.85.0.19130
725.85.0.192/2725.85.0.193 to 25.85.0.22225.85.0.22330
825.85.0.224/2725.85.0.225 to 25.85.0.25425.85.0.25530
925.85.1.0/2725.85.1.1 to 25.85.1.3025.85.1.3130
1025.85.1.32/2725.85.1.33 to 25.85.1.6225.85.1.6330
1125.85.1.64/2725.85.1.65 to 25.85.1.9425.85.1.9530
1225.85.1.96/2725.85.1.97 to 25.85.1.12625.85.1.12730
1325.85.1.128/2725.85.1.129 to 25.85.1.15825.85.1.15930
1425.85.1.160/2725.85.1.161 to 25.85.1.19025.85.1.19130
1525.85.1.192/2725.85.1.193 to 25.85.1.22225.85.1.22330
1625.85.1.224/2725.85.1.225 to 25.85.1.25425.85.1.25530
1725.85.2.0/2725.85.2.1 to 25.85.2.3025.85.2.3130
1825.85.2.32/2725.85.2.33 to 25.85.2.6225.85.2.6330
1925.85.2.64/2725.85.2.65 to 25.85.2.9425.85.2.9530
2025.85.2.96/2725.85.2.97 to 25.85.2.12625.85.2.12730
2125.85.2.128/2725.85.2.129 to 25.85.2.15825.85.2.15930
2225.85.2.160/2725.85.2.161 to 25.85.2.19025.85.2.19130
2325.85.2.192/2725.85.2.193 to 25.85.2.22225.85.2.22330
2425.85.2.224/2725.85.2.225 to 25.85.2.25425.85.2.25530
2525.85.3.0/2725.85.3.1 to 25.85.3.3025.85.3.3130
2625.85.3.32/2725.85.3.33 to 25.85.3.6225.85.3.6330
2725.85.3.64/2725.85.3.65 to 25.85.3.9425.85.3.9530
2825.85.3.96/2725.85.3.97 to 25.85.3.12625.85.3.12730
2925.85.3.128/2725.85.3.129 to 25.85.3.15825.85.3.15930
3025.85.3.160/2725.85.3.161 to 25.85.3.19025.85.3.19130
3125.85.3.192/2725.85.3.193 to 25.85.3.22225.85.3.22330
3225.85.3.224/2725.85.3.225 to 25.85.3.25425.85.3.25530
3325.85.4.0/2725.85.4.1 to 25.85.4.3025.85.4.3130
3425.85.4.32/2725.85.4.33 to 25.85.4.6225.85.4.6330
3525.85.4.64/2725.85.4.65 to 25.85.4.9425.85.4.9530
3625.85.4.96/2725.85.4.97 to 25.85.4.12625.85.4.12730
3725.85.4.128/2725.85.4.129 to 25.85.4.15825.85.4.15930
3825.85.4.160/2725.85.4.161 to 25.85.4.19025.85.4.19130
3925.85.4.192/2725.85.4.193 to 25.85.4.22225.85.4.22330
4025.85.4.224/2725.85.4.225 to 25.85.4.25425.85.4.25530
4125.85.5.0/2725.85.5.1 to 25.85.5.3025.85.5.3130
4225.85.5.32/2725.85.5.33 to 25.85.5.6225.85.5.6330
4325.85.5.64/2725.85.5.65 to 25.85.5.9425.85.5.9530
4425.85.5.96/2725.85.5.97 to 25.85.5.12625.85.5.12730
4525.85.5.128/2725.85.5.129 to 25.85.5.15825.85.5.15930
4625.85.5.160/2725.85.5.161 to 25.85.5.19025.85.5.19130
4725.85.5.192/2725.85.5.193 to 25.85.5.22225.85.5.22330
4825.85.5.224/2725.85.5.225 to 25.85.5.25425.85.5.25530
4925.85.6.0/2725.85.6.1 to 25.85.6.3025.85.6.3130
5025.85.6.32/2725.85.6.33 to 25.85.6.6225.85.6.6330
5125.85.6.64/2725.85.6.65 to 25.85.6.9425.85.6.9530
5225.85.6.96/2725.85.6.97 to 25.85.6.12625.85.6.12730
5325.85.6.128/2725.85.6.129 to 25.85.6.15825.85.6.15930
5425.85.6.160/2725.85.6.161 to 25.85.6.19025.85.6.19130
5525.85.6.192/2725.85.6.193 to 25.85.6.22225.85.6.22330
5625.85.6.224/2725.85.6.225 to 25.85.6.25425.85.6.25530
5725.85.7.0/2725.85.7.1 to 25.85.7.3025.85.7.3130
5825.85.7.32/2725.85.7.33 to 25.85.7.6225.85.7.6330
5925.85.7.64/2725.85.7.65 to 25.85.7.9425.85.7.9530
6025.85.7.96/2725.85.7.97 to 25.85.7.12625.85.7.12730
6125.85.7.128/2725.85.7.129 to 25.85.7.15825.85.7.15930
6225.85.7.160/2725.85.7.161 to 25.85.7.19025.85.7.19130
6325.85.7.192/2725.85.7.193 to 25.85.7.22225.85.7.22330
6425.85.7.224/2725.85.7.225 to 25.85.7.25425.85.7.25530
6525.85.8.0/2725.85.8.1 to 25.85.8.3025.85.8.3130
6625.85.8.32/2725.85.8.33 to 25.85.8.6225.85.8.6330
6725.85.8.64/2725.85.8.65 to 25.85.8.9425.85.8.9530
6825.85.8.96/2725.85.8.97 to 25.85.8.12625.85.8.12730
6925.85.8.128/2725.85.8.129 to 25.85.8.15825.85.8.15930
7025.85.8.160/2725.85.8.161 to 25.85.8.19025.85.8.19130
7125.85.8.192/2725.85.8.193 to 25.85.8.22225.85.8.22330
7225.85.8.224/2725.85.8.225 to 25.85.8.25425.85.8.25530
7325.85.9.0/2725.85.9.1 to 25.85.9.3025.85.9.3130
7425.85.9.32/2725.85.9.33 to 25.85.9.6225.85.9.6330
7525.85.9.64/2725.85.9.65 to 25.85.9.9425.85.9.9530
7625.85.9.96/2725.85.9.97 to 25.85.9.12625.85.9.12730
7725.85.9.128/2725.85.9.129 to 25.85.9.15825.85.9.15930
7825.85.9.160/2725.85.9.161 to 25.85.9.19025.85.9.19130
7925.85.9.192/2725.85.9.193 to 25.85.9.22225.85.9.22330
8025.85.9.224/2725.85.9.225 to 25.85.9.25425.85.9.25530
8125.85.10.0/2725.85.10.1 to 25.85.10.3025.85.10.3130
8225.85.10.32/2725.85.10.33 to 25.85.10.6225.85.10.6330
8325.85.10.64/2725.85.10.65 to 25.85.10.9425.85.10.9530
8425.85.10.96/2725.85.10.97 to 25.85.10.12625.85.10.12730
8525.85.10.128/2725.85.10.129 to 25.85.10.15825.85.10.15930
8625.85.10.160/2725.85.10.161 to 25.85.10.19025.85.10.19130
8725.85.10.192/2725.85.10.193 to 25.85.10.22225.85.10.22330
8825.85.10.224/2725.85.10.225 to 25.85.10.25425.85.10.25530
8925.85.11.0/2725.85.11.1 to 25.85.11.3025.85.11.3130
9025.85.11.32/2725.85.11.33 to 25.85.11.6225.85.11.6330
9125.85.11.64/2725.85.11.65 to 25.85.11.9425.85.11.9530
9225.85.11.96/2725.85.11.97 to 25.85.11.12625.85.11.12730
9325.85.11.128/2725.85.11.129 to 25.85.11.15825.85.11.15930
9425.85.11.160/2725.85.11.161 to 25.85.11.19025.85.11.19130
9525.85.11.192/2725.85.11.193 to 25.85.11.22225.85.11.22330
9625.85.11.224/2725.85.11.225 to 25.85.11.25425.85.11.25530
9725.85.12.0/2725.85.12.1 to 25.85.12.3025.85.12.3130
9825.85.12.32/2725.85.12.33 to 25.85.12.6225.85.12.6330
9925.85.12.64/2725.85.12.65 to 25.85.12.9425.85.12.9530
10025.85.12.96/2725.85.12.97 to 25.85.12.12625.85.12.12730
10125.85.12.128/2725.85.12.129 to 25.85.12.15825.85.12.15930
10225.85.12.160/2725.85.12.161 to 25.85.12.19025.85.12.19130
10325.85.12.192/2725.85.12.193 to 25.85.12.22225.85.12.22330
10425.85.12.224/2725.85.12.225 to 25.85.12.25425.85.12.25530
10525.85.13.0/2725.85.13.1 to 25.85.13.3025.85.13.3130
10625.85.13.32/2725.85.13.33 to 25.85.13.6225.85.13.6330
10725.85.13.64/2725.85.13.65 to 25.85.13.9425.85.13.9530
10825.85.13.96/2725.85.13.97 to 25.85.13.12625.85.13.12730
10925.85.13.128/2725.85.13.129 to 25.85.13.15825.85.13.15930
11025.85.13.160/2725.85.13.161 to 25.85.13.19025.85.13.19130
11125.85.13.192/2725.85.13.193 to 25.85.13.22225.85.13.22330
11225.85.13.224/2725.85.13.225 to 25.85.13.25425.85.13.25530
11325.85.14.0/2725.85.14.1 to 25.85.14.3025.85.14.3130
11425.85.14.32/2725.85.14.33 to 25.85.14.6225.85.14.6330
11525.85.14.64/2725.85.14.65 to 25.85.14.9425.85.14.9530
11625.85.14.96/2725.85.14.97 to 25.85.14.12625.85.14.12730
11725.85.14.128/2725.85.14.129 to 25.85.14.15825.85.14.15930
11825.85.14.160/2725.85.14.161 to 25.85.14.19025.85.14.19130
11925.85.14.192/2725.85.14.193 to 25.85.14.22225.85.14.22330
12025.85.14.224/2725.85.14.225 to 25.85.14.25425.85.14.25530
12125.85.15.0/2725.85.15.1 to 25.85.15.3025.85.15.3130
12225.85.15.32/2725.85.15.33 to 25.85.15.6225.85.15.6330
12325.85.15.64/2725.85.15.65 to 25.85.15.9425.85.15.9530
12425.85.15.96/2725.85.15.97 to 25.85.15.12625.85.15.12730
12525.85.15.128/2725.85.15.129 to 25.85.15.15825.85.15.15930
12625.85.15.160/2725.85.15.161 to 25.85.15.19025.85.15.19130
12725.85.15.192/2725.85.15.193 to 25.85.15.22225.85.15.22330
12825.85.15.224/2725.85.15.225 to 25.85.15.25425.85.15.25530
12925.85.16.0/2725.85.16.1 to 25.85.16.3025.85.16.3130
13025.85.16.32/2725.85.16.33 to 25.85.16.6225.85.16.6330
13125.85.16.64/2725.85.16.65 to 25.85.16.9425.85.16.9530
13225.85.16.96/2725.85.16.97 to 25.85.16.12625.85.16.12730
13325.85.16.128/2725.85.16.129 to 25.85.16.15825.85.16.15930
13425.85.16.160/2725.85.16.161 to 25.85.16.19025.85.16.19130
13525.85.16.192/2725.85.16.193 to 25.85.16.22225.85.16.22330
13625.85.16.224/2725.85.16.225 to 25.85.16.25425.85.16.25530
13725.85.17.0/2725.85.17.1 to 25.85.17.3025.85.17.3130
13825.85.17.32/2725.85.17.33 to 25.85.17.6225.85.17.6330
13925.85.17.64/2725.85.17.65 to 25.85.17.9425.85.17.9530
14025.85.17.96/2725.85.17.97 to 25.85.17.12625.85.17.12730
14125.85.17.128/2725.85.17.129 to 25.85.17.15825.85.17.15930
14225.85.17.160/2725.85.17.161 to 25.85.17.19025.85.17.19130
14325.85.17.192/2725.85.17.193 to 25.85.17.22225.85.17.22330
14425.85.17.224/2725.85.17.225 to 25.85.17.25425.85.17.25530
14525.85.18.0/2725.85.18.1 to 25.85.18.3025.85.18.3130
14625.85.18.32/2725.85.18.33 to 25.85.18.6225.85.18.6330
14725.85.18.64/2725.85.18.65 to 25.85.18.9425.85.18.9530
14825.85.18.96/2725.85.18.97 to 25.85.18.12625.85.18.12730
14925.85.18.128/2725.85.18.129 to 25.85.18.15825.85.18.15930
15025.85.18.160/2725.85.18.161 to 25.85.18.19025.85.18.19130
15125.85.18.192/2725.85.18.193 to 25.85.18.22225.85.18.22330
15225.85.18.224/2725.85.18.225 to 25.85.18.25425.85.18.25530
15325.85.19.0/2725.85.19.1 to 25.85.19.3025.85.19.3130
15425.85.19.32/2725.85.19.33 to 25.85.19.6225.85.19.6330
15525.85.19.64/2725.85.19.65 to 25.85.19.9425.85.19.9530
15625.85.19.96/2725.85.19.97 to 25.85.19.12625.85.19.12730
15725.85.19.128/2725.85.19.129 to 25.85.19.15825.85.19.15930
15825.85.19.160/2725.85.19.161 to 25.85.19.19025.85.19.19130
15925.85.19.192/2725.85.19.193 to 25.85.19.22225.85.19.22330
16025.85.19.224/2725.85.19.225 to 25.85.19.25425.85.19.25530
16125.85.20.0/2725.85.20.1 to 25.85.20.3025.85.20.3130
16225.85.20.32/2725.85.20.33 to 25.85.20.6225.85.20.6330
16325.85.20.64/2725.85.20.65 to 25.85.20.9425.85.20.9530
16425.85.20.96/2725.85.20.97 to 25.85.20.12625.85.20.12730
16525.85.20.128/2725.85.20.129 to 25.85.20.15825.85.20.15930
16625.85.20.160/2725.85.20.161 to 25.85.20.19025.85.20.19130
16725.85.20.192/2725.85.20.193 to 25.85.20.22225.85.20.22330
16825.85.20.224/2725.85.20.225 to 25.85.20.25425.85.20.25530
16925.85.21.0/2725.85.21.1 to 25.85.21.3025.85.21.3130
17025.85.21.32/2725.85.21.33 to 25.85.21.6225.85.21.6330
17125.85.21.64/2725.85.21.65 to 25.85.21.9425.85.21.9530
17225.85.21.96/2725.85.21.97 to 25.85.21.12625.85.21.12730
17325.85.21.128/2725.85.21.129 to 25.85.21.15825.85.21.15930
17425.85.21.160/2725.85.21.161 to 25.85.21.19025.85.21.19130
17525.85.21.192/2725.85.21.193 to 25.85.21.22225.85.21.22330
17625.85.21.224/2725.85.21.225 to 25.85.21.25425.85.21.25530
17725.85.22.0/2725.85.22.1 to 25.85.22.3025.85.22.3130
17825.85.22.32/2725.85.22.33 to 25.85.22.6225.85.22.6330
17925.85.22.64/2725.85.22.65 to 25.85.22.9425.85.22.9530
18025.85.22.96/2725.85.22.97 to 25.85.22.12625.85.22.12730
18125.85.22.128/2725.85.22.129 to 25.85.22.15825.85.22.15930
18225.85.22.160/2725.85.22.161 to 25.85.22.19025.85.22.19130
18325.85.22.192/2725.85.22.193 to 25.85.22.22225.85.22.22330
18425.85.22.224/2725.85.22.225 to 25.85.22.25425.85.22.25530
18525.85.23.0/2725.85.23.1 to 25.85.23.3025.85.23.3130
18625.85.23.32/2725.85.23.33 to 25.85.23.6225.85.23.6330
18725.85.23.64/2725.85.23.65 to 25.85.23.9425.85.23.9530
18825.85.23.96/2725.85.23.97 to 25.85.23.12625.85.23.12730
18925.85.23.128/2725.85.23.129 to 25.85.23.15825.85.23.15930
19025.85.23.160/2725.85.23.161 to 25.85.23.19025.85.23.19130
19125.85.23.192/2725.85.23.193 to 25.85.23.22225.85.23.22330
19225.85.23.224/2725.85.23.225 to 25.85.23.25425.85.23.25530
19325.85.24.0/2725.85.24.1 to 25.85.24.3025.85.24.3130
19425.85.24.32/2725.85.24.33 to 25.85.24.6225.85.24.6330
19525.85.24.64/2725.85.24.65 to 25.85.24.9425.85.24.9530
19625.85.24.96/2725.85.24.97 to 25.85.24.12625.85.24.12730
19725.85.24.128/2725.85.24.129 to 25.85.24.15825.85.24.15930
19825.85.24.160/2725.85.24.161 to 25.85.24.19025.85.24.19130
19925.85.24.192/2725.85.24.193 to 25.85.24.22225.85.24.22330
20025.85.24.224/2725.85.24.225 to 25.85.24.25425.85.24.25530
20125.85.25.0/2725.85.25.1 to 25.85.25.3025.85.25.3130
20225.85.25.32/2725.85.25.33 to 25.85.25.6225.85.25.6330
20325.85.25.64/2725.85.25.65 to 25.85.25.9425.85.25.9530
20425.85.25.96/2725.85.25.97 to 25.85.25.12625.85.25.12730
20525.85.25.128/2725.85.25.129 to 25.85.25.15825.85.25.15930
20625.85.25.160/2725.85.25.161 to 25.85.25.19025.85.25.19130
20725.85.25.192/2725.85.25.193 to 25.85.25.22225.85.25.22330
20825.85.25.224/2725.85.25.225 to 25.85.25.25425.85.25.25530
20925.85.26.0/2725.85.26.1 to 25.85.26.3025.85.26.3130
21025.85.26.32/2725.85.26.33 to 25.85.26.6225.85.26.6330
21125.85.26.64/2725.85.26.65 to 25.85.26.9425.85.26.9530
21225.85.26.96/2725.85.26.97 to 25.85.26.12625.85.26.12730
21325.85.26.128/2725.85.26.129 to 25.85.26.15825.85.26.15930
21425.85.26.160/2725.85.26.161 to 25.85.26.19025.85.26.19130
21525.85.26.192/2725.85.26.193 to 25.85.26.22225.85.26.22330
21625.85.26.224/2725.85.26.225 to 25.85.26.25425.85.26.25530
21725.85.27.0/2725.85.27.1 to 25.85.27.3025.85.27.3130
21825.85.27.32/2725.85.27.33 to 25.85.27.6225.85.27.6330
21925.85.27.64/2725.85.27.65 to 25.85.27.9425.85.27.9530
22025.85.27.96/2725.85.27.97 to 25.85.27.12625.85.27.12730
22125.85.27.128/2725.85.27.129 to 25.85.27.15825.85.27.15930
22225.85.27.160/2725.85.27.161 to 25.85.27.19025.85.27.19130
22325.85.27.192/2725.85.27.193 to 25.85.27.22225.85.27.22330
22425.85.27.224/2725.85.27.225 to 25.85.27.25425.85.27.25530
22525.85.28.0/2725.85.28.1 to 25.85.28.3025.85.28.3130
22625.85.28.32/2725.85.28.33 to 25.85.28.6225.85.28.6330
22725.85.28.64/2725.85.28.65 to 25.85.28.9425.85.28.9530
22825.85.28.96/2725.85.28.97 to 25.85.28.12625.85.28.12730
22925.85.28.128/2725.85.28.129 to 25.85.28.15825.85.28.15930
23025.85.28.160/2725.85.28.161 to 25.85.28.19025.85.28.19130
23125.85.28.192/2725.85.28.193 to 25.85.28.22225.85.28.22330
23225.85.28.224/2725.85.28.225 to 25.85.28.25425.85.28.25530
23325.85.29.0/2725.85.29.1 to 25.85.29.3025.85.29.3130
23425.85.29.32/2725.85.29.33 to 25.85.29.6225.85.29.6330
23525.85.29.64/2725.85.29.65 to 25.85.29.9425.85.29.9530
23625.85.29.96/2725.85.29.97 to 25.85.29.12625.85.29.12730
23725.85.29.128/2725.85.29.129 to 25.85.29.15825.85.29.15930
23825.85.29.160/2725.85.29.161 to 25.85.29.19025.85.29.19130
23925.85.29.192/2725.85.29.193 to 25.85.29.22225.85.29.22330
24025.85.29.224/2725.85.29.225 to 25.85.29.25425.85.29.25530
24125.85.30.0/2725.85.30.1 to 25.85.30.3025.85.30.3130
24225.85.30.32/2725.85.30.33 to 25.85.30.6225.85.30.6330
24325.85.30.64/2725.85.30.65 to 25.85.30.9425.85.30.9530
24425.85.30.96/2725.85.30.97 to 25.85.30.12625.85.30.12730
24525.85.30.128/2725.85.30.129 to 25.85.30.15825.85.30.15930
24625.85.30.160/2725.85.30.161 to 25.85.30.19025.85.30.19130
24725.85.30.192/2725.85.30.193 to 25.85.30.22225.85.30.22330
24825.85.30.224/2725.85.30.225 to 25.85.30.25425.85.30.25530
24925.85.31.0/2725.85.31.1 to 25.85.31.3025.85.31.3130
25025.85.31.32/2725.85.31.33 to 25.85.31.6225.85.31.6330
25125.85.31.64/2725.85.31.65 to 25.85.31.9425.85.31.9530
25225.85.31.96/2725.85.31.97 to 25.85.31.12625.85.31.12730
25325.85.31.128/2725.85.31.129 to 25.85.31.15825.85.31.15930
25425.85.31.160/2725.85.31.161 to 25.85.31.19025.85.31.19130
25525.85.31.192/2725.85.31.193 to 25.85.31.22225.85.31.22330
25625.85.31.224/2725.85.31.225 to 25.85.31.25425.85.31.25530

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.