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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.

Network25.2.80.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
25.2.80.0
Broadcast address
25.2.95.255
First usable
25.2.80.1
Last usable
25.2.95.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 19025000 · Integer 419581952 to 419586047
Reverse DNS zones
80.2.25.in-addr.arpa
81.2.25.in-addr.arpa
82.2.25.in-addr.arpa
83.2.25.in-addr.arpa
84.2.25.in-addr.arpa
85.2.25.in-addr.arpa
86.2.25.in-addr.arpa
87.2.25.in-addr.arpa
88.2.25.in-addr.arpa
89.2.25.in-addr.arpa
90.2.25.in-addr.arpa
91.2.25.in-addr.arpa
92.2.25.in-addr.arpa
93.2.25.in-addr.arpa
94.2.25.in-addr.arpa
95.2.25.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011001.00000010.01010000.0000000025.2.80.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00011001.00000010.01010000.0000000025.2.80.0
Broadcast00011001.00000010.01011111.1111111125.2.95.255
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

25.2.80.0/20 makes 256 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.2.80.0/2825.2.80.1 to 25.2.80.1425.2.80.1514
225.2.80.16/2825.2.80.17 to 25.2.80.3025.2.80.3114
325.2.80.32/2825.2.80.33 to 25.2.80.4625.2.80.4714
425.2.80.48/2825.2.80.49 to 25.2.80.6225.2.80.6314
525.2.80.64/2825.2.80.65 to 25.2.80.7825.2.80.7914
625.2.80.80/2825.2.80.81 to 25.2.80.9425.2.80.9514
725.2.80.96/2825.2.80.97 to 25.2.80.11025.2.80.11114
825.2.80.112/2825.2.80.113 to 25.2.80.12625.2.80.12714
925.2.80.128/2825.2.80.129 to 25.2.80.14225.2.80.14314
1025.2.80.144/2825.2.80.145 to 25.2.80.15825.2.80.15914
1125.2.80.160/2825.2.80.161 to 25.2.80.17425.2.80.17514
1225.2.80.176/2825.2.80.177 to 25.2.80.19025.2.80.19114
1325.2.80.192/2825.2.80.193 to 25.2.80.20625.2.80.20714
1425.2.80.208/2825.2.80.209 to 25.2.80.22225.2.80.22314
1525.2.80.224/2825.2.80.225 to 25.2.80.23825.2.80.23914
1625.2.80.240/2825.2.80.241 to 25.2.80.25425.2.80.25514
1725.2.81.0/2825.2.81.1 to 25.2.81.1425.2.81.1514
1825.2.81.16/2825.2.81.17 to 25.2.81.3025.2.81.3114
1925.2.81.32/2825.2.81.33 to 25.2.81.4625.2.81.4714
2025.2.81.48/2825.2.81.49 to 25.2.81.6225.2.81.6314
2125.2.81.64/2825.2.81.65 to 25.2.81.7825.2.81.7914
2225.2.81.80/2825.2.81.81 to 25.2.81.9425.2.81.9514
2325.2.81.96/2825.2.81.97 to 25.2.81.11025.2.81.11114
2425.2.81.112/2825.2.81.113 to 25.2.81.12625.2.81.12714
2525.2.81.128/2825.2.81.129 to 25.2.81.14225.2.81.14314
2625.2.81.144/2825.2.81.145 to 25.2.81.15825.2.81.15914
2725.2.81.160/2825.2.81.161 to 25.2.81.17425.2.81.17514
2825.2.81.176/2825.2.81.177 to 25.2.81.19025.2.81.19114
2925.2.81.192/2825.2.81.193 to 25.2.81.20625.2.81.20714
3025.2.81.208/2825.2.81.209 to 25.2.81.22225.2.81.22314
3125.2.81.224/2825.2.81.225 to 25.2.81.23825.2.81.23914
3225.2.81.240/2825.2.81.241 to 25.2.81.25425.2.81.25514
3325.2.82.0/2825.2.82.1 to 25.2.82.1425.2.82.1514
3425.2.82.16/2825.2.82.17 to 25.2.82.3025.2.82.3114
3525.2.82.32/2825.2.82.33 to 25.2.82.4625.2.82.4714
3625.2.82.48/2825.2.82.49 to 25.2.82.6225.2.82.6314
3725.2.82.64/2825.2.82.65 to 25.2.82.7825.2.82.7914
3825.2.82.80/2825.2.82.81 to 25.2.82.9425.2.82.9514
3925.2.82.96/2825.2.82.97 to 25.2.82.11025.2.82.11114
4025.2.82.112/2825.2.82.113 to 25.2.82.12625.2.82.12714
4125.2.82.128/2825.2.82.129 to 25.2.82.14225.2.82.14314
4225.2.82.144/2825.2.82.145 to 25.2.82.15825.2.82.15914
4325.2.82.160/2825.2.82.161 to 25.2.82.17425.2.82.17514
4425.2.82.176/2825.2.82.177 to 25.2.82.19025.2.82.19114
4525.2.82.192/2825.2.82.193 to 25.2.82.20625.2.82.20714
4625.2.82.208/2825.2.82.209 to 25.2.82.22225.2.82.22314
4725.2.82.224/2825.2.82.225 to 25.2.82.23825.2.82.23914
4825.2.82.240/2825.2.82.241 to 25.2.82.25425.2.82.25514
4925.2.83.0/2825.2.83.1 to 25.2.83.1425.2.83.1514
5025.2.83.16/2825.2.83.17 to 25.2.83.3025.2.83.3114
5125.2.83.32/2825.2.83.33 to 25.2.83.4625.2.83.4714
5225.2.83.48/2825.2.83.49 to 25.2.83.6225.2.83.6314
5325.2.83.64/2825.2.83.65 to 25.2.83.7825.2.83.7914
5425.2.83.80/2825.2.83.81 to 25.2.83.9425.2.83.9514
5525.2.83.96/2825.2.83.97 to 25.2.83.11025.2.83.11114
5625.2.83.112/2825.2.83.113 to 25.2.83.12625.2.83.12714
5725.2.83.128/2825.2.83.129 to 25.2.83.14225.2.83.14314
5825.2.83.144/2825.2.83.145 to 25.2.83.15825.2.83.15914
5925.2.83.160/2825.2.83.161 to 25.2.83.17425.2.83.17514
6025.2.83.176/2825.2.83.177 to 25.2.83.19025.2.83.19114
6125.2.83.192/2825.2.83.193 to 25.2.83.20625.2.83.20714
6225.2.83.208/2825.2.83.209 to 25.2.83.22225.2.83.22314
6325.2.83.224/2825.2.83.225 to 25.2.83.23825.2.83.23914
6425.2.83.240/2825.2.83.241 to 25.2.83.25425.2.83.25514
6525.2.84.0/2825.2.84.1 to 25.2.84.1425.2.84.1514
6625.2.84.16/2825.2.84.17 to 25.2.84.3025.2.84.3114
6725.2.84.32/2825.2.84.33 to 25.2.84.4625.2.84.4714
6825.2.84.48/2825.2.84.49 to 25.2.84.6225.2.84.6314
6925.2.84.64/2825.2.84.65 to 25.2.84.7825.2.84.7914
7025.2.84.80/2825.2.84.81 to 25.2.84.9425.2.84.9514
7125.2.84.96/2825.2.84.97 to 25.2.84.11025.2.84.11114
7225.2.84.112/2825.2.84.113 to 25.2.84.12625.2.84.12714
7325.2.84.128/2825.2.84.129 to 25.2.84.14225.2.84.14314
7425.2.84.144/2825.2.84.145 to 25.2.84.15825.2.84.15914
7525.2.84.160/2825.2.84.161 to 25.2.84.17425.2.84.17514
7625.2.84.176/2825.2.84.177 to 25.2.84.19025.2.84.19114
7725.2.84.192/2825.2.84.193 to 25.2.84.20625.2.84.20714
7825.2.84.208/2825.2.84.209 to 25.2.84.22225.2.84.22314
7925.2.84.224/2825.2.84.225 to 25.2.84.23825.2.84.23914
8025.2.84.240/2825.2.84.241 to 25.2.84.25425.2.84.25514
8125.2.85.0/2825.2.85.1 to 25.2.85.1425.2.85.1514
8225.2.85.16/2825.2.85.17 to 25.2.85.3025.2.85.3114
8325.2.85.32/2825.2.85.33 to 25.2.85.4625.2.85.4714
8425.2.85.48/2825.2.85.49 to 25.2.85.6225.2.85.6314
8525.2.85.64/2825.2.85.65 to 25.2.85.7825.2.85.7914
8625.2.85.80/2825.2.85.81 to 25.2.85.9425.2.85.9514
8725.2.85.96/2825.2.85.97 to 25.2.85.11025.2.85.11114
8825.2.85.112/2825.2.85.113 to 25.2.85.12625.2.85.12714
8925.2.85.128/2825.2.85.129 to 25.2.85.14225.2.85.14314
9025.2.85.144/2825.2.85.145 to 25.2.85.15825.2.85.15914
9125.2.85.160/2825.2.85.161 to 25.2.85.17425.2.85.17514
9225.2.85.176/2825.2.85.177 to 25.2.85.19025.2.85.19114
9325.2.85.192/2825.2.85.193 to 25.2.85.20625.2.85.20714
9425.2.85.208/2825.2.85.209 to 25.2.85.22225.2.85.22314
9525.2.85.224/2825.2.85.225 to 25.2.85.23825.2.85.23914
9625.2.85.240/2825.2.85.241 to 25.2.85.25425.2.85.25514
9725.2.86.0/2825.2.86.1 to 25.2.86.1425.2.86.1514
9825.2.86.16/2825.2.86.17 to 25.2.86.3025.2.86.3114
9925.2.86.32/2825.2.86.33 to 25.2.86.4625.2.86.4714
10025.2.86.48/2825.2.86.49 to 25.2.86.6225.2.86.6314
10125.2.86.64/2825.2.86.65 to 25.2.86.7825.2.86.7914
10225.2.86.80/2825.2.86.81 to 25.2.86.9425.2.86.9514
10325.2.86.96/2825.2.86.97 to 25.2.86.11025.2.86.11114
10425.2.86.112/2825.2.86.113 to 25.2.86.12625.2.86.12714
10525.2.86.128/2825.2.86.129 to 25.2.86.14225.2.86.14314
10625.2.86.144/2825.2.86.145 to 25.2.86.15825.2.86.15914
10725.2.86.160/2825.2.86.161 to 25.2.86.17425.2.86.17514
10825.2.86.176/2825.2.86.177 to 25.2.86.19025.2.86.19114
10925.2.86.192/2825.2.86.193 to 25.2.86.20625.2.86.20714
11025.2.86.208/2825.2.86.209 to 25.2.86.22225.2.86.22314
11125.2.86.224/2825.2.86.225 to 25.2.86.23825.2.86.23914
11225.2.86.240/2825.2.86.241 to 25.2.86.25425.2.86.25514
11325.2.87.0/2825.2.87.1 to 25.2.87.1425.2.87.1514
11425.2.87.16/2825.2.87.17 to 25.2.87.3025.2.87.3114
11525.2.87.32/2825.2.87.33 to 25.2.87.4625.2.87.4714
11625.2.87.48/2825.2.87.49 to 25.2.87.6225.2.87.6314
11725.2.87.64/2825.2.87.65 to 25.2.87.7825.2.87.7914
11825.2.87.80/2825.2.87.81 to 25.2.87.9425.2.87.9514
11925.2.87.96/2825.2.87.97 to 25.2.87.11025.2.87.11114
12025.2.87.112/2825.2.87.113 to 25.2.87.12625.2.87.12714
12125.2.87.128/2825.2.87.129 to 25.2.87.14225.2.87.14314
12225.2.87.144/2825.2.87.145 to 25.2.87.15825.2.87.15914
12325.2.87.160/2825.2.87.161 to 25.2.87.17425.2.87.17514
12425.2.87.176/2825.2.87.177 to 25.2.87.19025.2.87.19114
12525.2.87.192/2825.2.87.193 to 25.2.87.20625.2.87.20714
12625.2.87.208/2825.2.87.209 to 25.2.87.22225.2.87.22314
12725.2.87.224/2825.2.87.225 to 25.2.87.23825.2.87.23914
12825.2.87.240/2825.2.87.241 to 25.2.87.25425.2.87.25514
12925.2.88.0/2825.2.88.1 to 25.2.88.1425.2.88.1514
13025.2.88.16/2825.2.88.17 to 25.2.88.3025.2.88.3114
13125.2.88.32/2825.2.88.33 to 25.2.88.4625.2.88.4714
13225.2.88.48/2825.2.88.49 to 25.2.88.6225.2.88.6314
13325.2.88.64/2825.2.88.65 to 25.2.88.7825.2.88.7914
13425.2.88.80/2825.2.88.81 to 25.2.88.9425.2.88.9514
13525.2.88.96/2825.2.88.97 to 25.2.88.11025.2.88.11114
13625.2.88.112/2825.2.88.113 to 25.2.88.12625.2.88.12714
13725.2.88.128/2825.2.88.129 to 25.2.88.14225.2.88.14314
13825.2.88.144/2825.2.88.145 to 25.2.88.15825.2.88.15914
13925.2.88.160/2825.2.88.161 to 25.2.88.17425.2.88.17514
14025.2.88.176/2825.2.88.177 to 25.2.88.19025.2.88.19114
14125.2.88.192/2825.2.88.193 to 25.2.88.20625.2.88.20714
14225.2.88.208/2825.2.88.209 to 25.2.88.22225.2.88.22314
14325.2.88.224/2825.2.88.225 to 25.2.88.23825.2.88.23914
14425.2.88.240/2825.2.88.241 to 25.2.88.25425.2.88.25514
14525.2.89.0/2825.2.89.1 to 25.2.89.1425.2.89.1514
14625.2.89.16/2825.2.89.17 to 25.2.89.3025.2.89.3114
14725.2.89.32/2825.2.89.33 to 25.2.89.4625.2.89.4714
14825.2.89.48/2825.2.89.49 to 25.2.89.6225.2.89.6314
14925.2.89.64/2825.2.89.65 to 25.2.89.7825.2.89.7914
15025.2.89.80/2825.2.89.81 to 25.2.89.9425.2.89.9514
15125.2.89.96/2825.2.89.97 to 25.2.89.11025.2.89.11114
15225.2.89.112/2825.2.89.113 to 25.2.89.12625.2.89.12714
15325.2.89.128/2825.2.89.129 to 25.2.89.14225.2.89.14314
15425.2.89.144/2825.2.89.145 to 25.2.89.15825.2.89.15914
15525.2.89.160/2825.2.89.161 to 25.2.89.17425.2.89.17514
15625.2.89.176/2825.2.89.177 to 25.2.89.19025.2.89.19114
15725.2.89.192/2825.2.89.193 to 25.2.89.20625.2.89.20714
15825.2.89.208/2825.2.89.209 to 25.2.89.22225.2.89.22314
15925.2.89.224/2825.2.89.225 to 25.2.89.23825.2.89.23914
16025.2.89.240/2825.2.89.241 to 25.2.89.25425.2.89.25514
16125.2.90.0/2825.2.90.1 to 25.2.90.1425.2.90.1514
16225.2.90.16/2825.2.90.17 to 25.2.90.3025.2.90.3114
16325.2.90.32/2825.2.90.33 to 25.2.90.4625.2.90.4714
16425.2.90.48/2825.2.90.49 to 25.2.90.6225.2.90.6314
16525.2.90.64/2825.2.90.65 to 25.2.90.7825.2.90.7914
16625.2.90.80/2825.2.90.81 to 25.2.90.9425.2.90.9514
16725.2.90.96/2825.2.90.97 to 25.2.90.11025.2.90.11114
16825.2.90.112/2825.2.90.113 to 25.2.90.12625.2.90.12714
16925.2.90.128/2825.2.90.129 to 25.2.90.14225.2.90.14314
17025.2.90.144/2825.2.90.145 to 25.2.90.15825.2.90.15914
17125.2.90.160/2825.2.90.161 to 25.2.90.17425.2.90.17514
17225.2.90.176/2825.2.90.177 to 25.2.90.19025.2.90.19114
17325.2.90.192/2825.2.90.193 to 25.2.90.20625.2.90.20714
17425.2.90.208/2825.2.90.209 to 25.2.90.22225.2.90.22314
17525.2.90.224/2825.2.90.225 to 25.2.90.23825.2.90.23914
17625.2.90.240/2825.2.90.241 to 25.2.90.25425.2.90.25514
17725.2.91.0/2825.2.91.1 to 25.2.91.1425.2.91.1514
17825.2.91.16/2825.2.91.17 to 25.2.91.3025.2.91.3114
17925.2.91.32/2825.2.91.33 to 25.2.91.4625.2.91.4714
18025.2.91.48/2825.2.91.49 to 25.2.91.6225.2.91.6314
18125.2.91.64/2825.2.91.65 to 25.2.91.7825.2.91.7914
18225.2.91.80/2825.2.91.81 to 25.2.91.9425.2.91.9514
18325.2.91.96/2825.2.91.97 to 25.2.91.11025.2.91.11114
18425.2.91.112/2825.2.91.113 to 25.2.91.12625.2.91.12714
18525.2.91.128/2825.2.91.129 to 25.2.91.14225.2.91.14314
18625.2.91.144/2825.2.91.145 to 25.2.91.15825.2.91.15914
18725.2.91.160/2825.2.91.161 to 25.2.91.17425.2.91.17514
18825.2.91.176/2825.2.91.177 to 25.2.91.19025.2.91.19114
18925.2.91.192/2825.2.91.193 to 25.2.91.20625.2.91.20714
19025.2.91.208/2825.2.91.209 to 25.2.91.22225.2.91.22314
19125.2.91.224/2825.2.91.225 to 25.2.91.23825.2.91.23914
19225.2.91.240/2825.2.91.241 to 25.2.91.25425.2.91.25514
19325.2.92.0/2825.2.92.1 to 25.2.92.1425.2.92.1514
19425.2.92.16/2825.2.92.17 to 25.2.92.3025.2.92.3114
19525.2.92.32/2825.2.92.33 to 25.2.92.4625.2.92.4714
19625.2.92.48/2825.2.92.49 to 25.2.92.6225.2.92.6314
19725.2.92.64/2825.2.92.65 to 25.2.92.7825.2.92.7914
19825.2.92.80/2825.2.92.81 to 25.2.92.9425.2.92.9514
19925.2.92.96/2825.2.92.97 to 25.2.92.11025.2.92.11114
20025.2.92.112/2825.2.92.113 to 25.2.92.12625.2.92.12714
20125.2.92.128/2825.2.92.129 to 25.2.92.14225.2.92.14314
20225.2.92.144/2825.2.92.145 to 25.2.92.15825.2.92.15914
20325.2.92.160/2825.2.92.161 to 25.2.92.17425.2.92.17514
20425.2.92.176/2825.2.92.177 to 25.2.92.19025.2.92.19114
20525.2.92.192/2825.2.92.193 to 25.2.92.20625.2.92.20714
20625.2.92.208/2825.2.92.209 to 25.2.92.22225.2.92.22314
20725.2.92.224/2825.2.92.225 to 25.2.92.23825.2.92.23914
20825.2.92.240/2825.2.92.241 to 25.2.92.25425.2.92.25514
20925.2.93.0/2825.2.93.1 to 25.2.93.1425.2.93.1514
21025.2.93.16/2825.2.93.17 to 25.2.93.3025.2.93.3114
21125.2.93.32/2825.2.93.33 to 25.2.93.4625.2.93.4714
21225.2.93.48/2825.2.93.49 to 25.2.93.6225.2.93.6314
21325.2.93.64/2825.2.93.65 to 25.2.93.7825.2.93.7914
21425.2.93.80/2825.2.93.81 to 25.2.93.9425.2.93.9514
21525.2.93.96/2825.2.93.97 to 25.2.93.11025.2.93.11114
21625.2.93.112/2825.2.93.113 to 25.2.93.12625.2.93.12714
21725.2.93.128/2825.2.93.129 to 25.2.93.14225.2.93.14314
21825.2.93.144/2825.2.93.145 to 25.2.93.15825.2.93.15914
21925.2.93.160/2825.2.93.161 to 25.2.93.17425.2.93.17514
22025.2.93.176/2825.2.93.177 to 25.2.93.19025.2.93.19114
22125.2.93.192/2825.2.93.193 to 25.2.93.20625.2.93.20714
22225.2.93.208/2825.2.93.209 to 25.2.93.22225.2.93.22314
22325.2.93.224/2825.2.93.225 to 25.2.93.23825.2.93.23914
22425.2.93.240/2825.2.93.241 to 25.2.93.25425.2.93.25514
22525.2.94.0/2825.2.94.1 to 25.2.94.1425.2.94.1514
22625.2.94.16/2825.2.94.17 to 25.2.94.3025.2.94.3114
22725.2.94.32/2825.2.94.33 to 25.2.94.4625.2.94.4714
22825.2.94.48/2825.2.94.49 to 25.2.94.6225.2.94.6314
22925.2.94.64/2825.2.94.65 to 25.2.94.7825.2.94.7914
23025.2.94.80/2825.2.94.81 to 25.2.94.9425.2.94.9514
23125.2.94.96/2825.2.94.97 to 25.2.94.11025.2.94.11114
23225.2.94.112/2825.2.94.113 to 25.2.94.12625.2.94.12714
23325.2.94.128/2825.2.94.129 to 25.2.94.14225.2.94.14314
23425.2.94.144/2825.2.94.145 to 25.2.94.15825.2.94.15914
23525.2.94.160/2825.2.94.161 to 25.2.94.17425.2.94.17514
23625.2.94.176/2825.2.94.177 to 25.2.94.19025.2.94.19114
23725.2.94.192/2825.2.94.193 to 25.2.94.20625.2.94.20714
23825.2.94.208/2825.2.94.209 to 25.2.94.22225.2.94.22314
23925.2.94.224/2825.2.94.225 to 25.2.94.23825.2.94.23914
24025.2.94.240/2825.2.94.241 to 25.2.94.25425.2.94.25514
24125.2.95.0/2825.2.95.1 to 25.2.95.1425.2.95.1514
24225.2.95.16/2825.2.95.17 to 25.2.95.3025.2.95.3114
24325.2.95.32/2825.2.95.33 to 25.2.95.4625.2.95.4714
24425.2.95.48/2825.2.95.49 to 25.2.95.6225.2.95.6314
24525.2.95.64/2825.2.95.65 to 25.2.95.7825.2.95.7914
24625.2.95.80/2825.2.95.81 to 25.2.95.9425.2.95.9514
24725.2.95.96/2825.2.95.97 to 25.2.95.11025.2.95.11114
24825.2.95.112/2825.2.95.113 to 25.2.95.12625.2.95.12714
24925.2.95.128/2825.2.95.129 to 25.2.95.14225.2.95.14314
25025.2.95.144/2825.2.95.145 to 25.2.95.15825.2.95.15914
25125.2.95.160/2825.2.95.161 to 25.2.95.17425.2.95.17514
25225.2.95.176/2825.2.95.177 to 25.2.95.19025.2.95.19114
25325.2.95.192/2825.2.95.193 to 25.2.95.20625.2.95.20714
25425.2.95.208/2825.2.95.209 to 25.2.95.22225.2.95.22314
25525.2.95.224/2825.2.95.225 to 25.2.95.23825.2.95.23914
25625.2.95.240/2825.2.95.241 to 25.2.95.25425.2.95.25514

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.