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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.

Network40.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
40.0.0.0
Broadcast address
40.63.255.255
First usable
40.0.0.1
Last usable
40.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 28000000 · Integer 671088640 to 675282943
Reverse DNS zones
0.40.in-addr.arpa
1.40.in-addr.arpa
2.40.in-addr.arpa
3.40.in-addr.arpa
4.40.in-addr.arpa
5.40.in-addr.arpa
6.40.in-addr.arpa
7.40.in-addr.arpa
8.40.in-addr.arpa
9.40.in-addr.arpa
10.40.in-addr.arpa
11.40.in-addr.arpa
12.40.in-addr.arpa
13.40.in-addr.arpa
14.40.in-addr.arpa
15.40.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101000.00000000.00000000.0000000040.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00101000.00000000.00000000.0000000040.0.0.0
Broadcast00101000.00111111.11111111.1111111140.63.255.255
Split into smaller subnets/18
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

40.0.0.0/10 makes 256 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
140.0.0.0/1840.0.0.1 to 40.0.63.25440.0.63.25516,382
240.0.64.0/1840.0.64.1 to 40.0.127.25440.0.127.25516,382
340.0.128.0/1840.0.128.1 to 40.0.191.25440.0.191.25516,382
440.0.192.0/1840.0.192.1 to 40.0.255.25440.0.255.25516,382
540.1.0.0/1840.1.0.1 to 40.1.63.25440.1.63.25516,382
640.1.64.0/1840.1.64.1 to 40.1.127.25440.1.127.25516,382
740.1.128.0/1840.1.128.1 to 40.1.191.25440.1.191.25516,382
840.1.192.0/1840.1.192.1 to 40.1.255.25440.1.255.25516,382
940.2.0.0/1840.2.0.1 to 40.2.63.25440.2.63.25516,382
1040.2.64.0/1840.2.64.1 to 40.2.127.25440.2.127.25516,382
1140.2.128.0/1840.2.128.1 to 40.2.191.25440.2.191.25516,382
1240.2.192.0/1840.2.192.1 to 40.2.255.25440.2.255.25516,382
1340.3.0.0/1840.3.0.1 to 40.3.63.25440.3.63.25516,382
1440.3.64.0/1840.3.64.1 to 40.3.127.25440.3.127.25516,382
1540.3.128.0/1840.3.128.1 to 40.3.191.25440.3.191.25516,382
1640.3.192.0/1840.3.192.1 to 40.3.255.25440.3.255.25516,382
1740.4.0.0/1840.4.0.1 to 40.4.63.25440.4.63.25516,382
1840.4.64.0/1840.4.64.1 to 40.4.127.25440.4.127.25516,382
1940.4.128.0/1840.4.128.1 to 40.4.191.25440.4.191.25516,382
2040.4.192.0/1840.4.192.1 to 40.4.255.25440.4.255.25516,382
2140.5.0.0/1840.5.0.1 to 40.5.63.25440.5.63.25516,382
2240.5.64.0/1840.5.64.1 to 40.5.127.25440.5.127.25516,382
2340.5.128.0/1840.5.128.1 to 40.5.191.25440.5.191.25516,382
2440.5.192.0/1840.5.192.1 to 40.5.255.25440.5.255.25516,382
2540.6.0.0/1840.6.0.1 to 40.6.63.25440.6.63.25516,382
2640.6.64.0/1840.6.64.1 to 40.6.127.25440.6.127.25516,382
2740.6.128.0/1840.6.128.1 to 40.6.191.25440.6.191.25516,382
2840.6.192.0/1840.6.192.1 to 40.6.255.25440.6.255.25516,382
2940.7.0.0/1840.7.0.1 to 40.7.63.25440.7.63.25516,382
3040.7.64.0/1840.7.64.1 to 40.7.127.25440.7.127.25516,382
3140.7.128.0/1840.7.128.1 to 40.7.191.25440.7.191.25516,382
3240.7.192.0/1840.7.192.1 to 40.7.255.25440.7.255.25516,382
3340.8.0.0/1840.8.0.1 to 40.8.63.25440.8.63.25516,382
3440.8.64.0/1840.8.64.1 to 40.8.127.25440.8.127.25516,382
3540.8.128.0/1840.8.128.1 to 40.8.191.25440.8.191.25516,382
3640.8.192.0/1840.8.192.1 to 40.8.255.25440.8.255.25516,382
3740.9.0.0/1840.9.0.1 to 40.9.63.25440.9.63.25516,382
3840.9.64.0/1840.9.64.1 to 40.9.127.25440.9.127.25516,382
3940.9.128.0/1840.9.128.1 to 40.9.191.25440.9.191.25516,382
4040.9.192.0/1840.9.192.1 to 40.9.255.25440.9.255.25516,382
4140.10.0.0/1840.10.0.1 to 40.10.63.25440.10.63.25516,382
4240.10.64.0/1840.10.64.1 to 40.10.127.25440.10.127.25516,382
4340.10.128.0/1840.10.128.1 to 40.10.191.25440.10.191.25516,382
4440.10.192.0/1840.10.192.1 to 40.10.255.25440.10.255.25516,382
4540.11.0.0/1840.11.0.1 to 40.11.63.25440.11.63.25516,382
4640.11.64.0/1840.11.64.1 to 40.11.127.25440.11.127.25516,382
4740.11.128.0/1840.11.128.1 to 40.11.191.25440.11.191.25516,382
4840.11.192.0/1840.11.192.1 to 40.11.255.25440.11.255.25516,382
4940.12.0.0/1840.12.0.1 to 40.12.63.25440.12.63.25516,382
5040.12.64.0/1840.12.64.1 to 40.12.127.25440.12.127.25516,382
5140.12.128.0/1840.12.128.1 to 40.12.191.25440.12.191.25516,382
5240.12.192.0/1840.12.192.1 to 40.12.255.25440.12.255.25516,382
5340.13.0.0/1840.13.0.1 to 40.13.63.25440.13.63.25516,382
5440.13.64.0/1840.13.64.1 to 40.13.127.25440.13.127.25516,382
5540.13.128.0/1840.13.128.1 to 40.13.191.25440.13.191.25516,382
5640.13.192.0/1840.13.192.1 to 40.13.255.25440.13.255.25516,382
5740.14.0.0/1840.14.0.1 to 40.14.63.25440.14.63.25516,382
5840.14.64.0/1840.14.64.1 to 40.14.127.25440.14.127.25516,382
5940.14.128.0/1840.14.128.1 to 40.14.191.25440.14.191.25516,382
6040.14.192.0/1840.14.192.1 to 40.14.255.25440.14.255.25516,382
6140.15.0.0/1840.15.0.1 to 40.15.63.25440.15.63.25516,382
6240.15.64.0/1840.15.64.1 to 40.15.127.25440.15.127.25516,382
6340.15.128.0/1840.15.128.1 to 40.15.191.25440.15.191.25516,382
6440.15.192.0/1840.15.192.1 to 40.15.255.25440.15.255.25516,382
6540.16.0.0/1840.16.0.1 to 40.16.63.25440.16.63.25516,382
6640.16.64.0/1840.16.64.1 to 40.16.127.25440.16.127.25516,382
6740.16.128.0/1840.16.128.1 to 40.16.191.25440.16.191.25516,382
6840.16.192.0/1840.16.192.1 to 40.16.255.25440.16.255.25516,382
6940.17.0.0/1840.17.0.1 to 40.17.63.25440.17.63.25516,382
7040.17.64.0/1840.17.64.1 to 40.17.127.25440.17.127.25516,382
7140.17.128.0/1840.17.128.1 to 40.17.191.25440.17.191.25516,382
7240.17.192.0/1840.17.192.1 to 40.17.255.25440.17.255.25516,382
7340.18.0.0/1840.18.0.1 to 40.18.63.25440.18.63.25516,382
7440.18.64.0/1840.18.64.1 to 40.18.127.25440.18.127.25516,382
7540.18.128.0/1840.18.128.1 to 40.18.191.25440.18.191.25516,382
7640.18.192.0/1840.18.192.1 to 40.18.255.25440.18.255.25516,382
7740.19.0.0/1840.19.0.1 to 40.19.63.25440.19.63.25516,382
7840.19.64.0/1840.19.64.1 to 40.19.127.25440.19.127.25516,382
7940.19.128.0/1840.19.128.1 to 40.19.191.25440.19.191.25516,382
8040.19.192.0/1840.19.192.1 to 40.19.255.25440.19.255.25516,382
8140.20.0.0/1840.20.0.1 to 40.20.63.25440.20.63.25516,382
8240.20.64.0/1840.20.64.1 to 40.20.127.25440.20.127.25516,382
8340.20.128.0/1840.20.128.1 to 40.20.191.25440.20.191.25516,382
8440.20.192.0/1840.20.192.1 to 40.20.255.25440.20.255.25516,382
8540.21.0.0/1840.21.0.1 to 40.21.63.25440.21.63.25516,382
8640.21.64.0/1840.21.64.1 to 40.21.127.25440.21.127.25516,382
8740.21.128.0/1840.21.128.1 to 40.21.191.25440.21.191.25516,382
8840.21.192.0/1840.21.192.1 to 40.21.255.25440.21.255.25516,382
8940.22.0.0/1840.22.0.1 to 40.22.63.25440.22.63.25516,382
9040.22.64.0/1840.22.64.1 to 40.22.127.25440.22.127.25516,382
9140.22.128.0/1840.22.128.1 to 40.22.191.25440.22.191.25516,382
9240.22.192.0/1840.22.192.1 to 40.22.255.25440.22.255.25516,382
9340.23.0.0/1840.23.0.1 to 40.23.63.25440.23.63.25516,382
9440.23.64.0/1840.23.64.1 to 40.23.127.25440.23.127.25516,382
9540.23.128.0/1840.23.128.1 to 40.23.191.25440.23.191.25516,382
9640.23.192.0/1840.23.192.1 to 40.23.255.25440.23.255.25516,382
9740.24.0.0/1840.24.0.1 to 40.24.63.25440.24.63.25516,382
9840.24.64.0/1840.24.64.1 to 40.24.127.25440.24.127.25516,382
9940.24.128.0/1840.24.128.1 to 40.24.191.25440.24.191.25516,382
10040.24.192.0/1840.24.192.1 to 40.24.255.25440.24.255.25516,382
10140.25.0.0/1840.25.0.1 to 40.25.63.25440.25.63.25516,382
10240.25.64.0/1840.25.64.1 to 40.25.127.25440.25.127.25516,382
10340.25.128.0/1840.25.128.1 to 40.25.191.25440.25.191.25516,382
10440.25.192.0/1840.25.192.1 to 40.25.255.25440.25.255.25516,382
10540.26.0.0/1840.26.0.1 to 40.26.63.25440.26.63.25516,382
10640.26.64.0/1840.26.64.1 to 40.26.127.25440.26.127.25516,382
10740.26.128.0/1840.26.128.1 to 40.26.191.25440.26.191.25516,382
10840.26.192.0/1840.26.192.1 to 40.26.255.25440.26.255.25516,382
10940.27.0.0/1840.27.0.1 to 40.27.63.25440.27.63.25516,382
11040.27.64.0/1840.27.64.1 to 40.27.127.25440.27.127.25516,382
11140.27.128.0/1840.27.128.1 to 40.27.191.25440.27.191.25516,382
11240.27.192.0/1840.27.192.1 to 40.27.255.25440.27.255.25516,382
11340.28.0.0/1840.28.0.1 to 40.28.63.25440.28.63.25516,382
11440.28.64.0/1840.28.64.1 to 40.28.127.25440.28.127.25516,382
11540.28.128.0/1840.28.128.1 to 40.28.191.25440.28.191.25516,382
11640.28.192.0/1840.28.192.1 to 40.28.255.25440.28.255.25516,382
11740.29.0.0/1840.29.0.1 to 40.29.63.25440.29.63.25516,382
11840.29.64.0/1840.29.64.1 to 40.29.127.25440.29.127.25516,382
11940.29.128.0/1840.29.128.1 to 40.29.191.25440.29.191.25516,382
12040.29.192.0/1840.29.192.1 to 40.29.255.25440.29.255.25516,382
12140.30.0.0/1840.30.0.1 to 40.30.63.25440.30.63.25516,382
12240.30.64.0/1840.30.64.1 to 40.30.127.25440.30.127.25516,382
12340.30.128.0/1840.30.128.1 to 40.30.191.25440.30.191.25516,382
12440.30.192.0/1840.30.192.1 to 40.30.255.25440.30.255.25516,382
12540.31.0.0/1840.31.0.1 to 40.31.63.25440.31.63.25516,382
12640.31.64.0/1840.31.64.1 to 40.31.127.25440.31.127.25516,382
12740.31.128.0/1840.31.128.1 to 40.31.191.25440.31.191.25516,382
12840.31.192.0/1840.31.192.1 to 40.31.255.25440.31.255.25516,382
12940.32.0.0/1840.32.0.1 to 40.32.63.25440.32.63.25516,382
13040.32.64.0/1840.32.64.1 to 40.32.127.25440.32.127.25516,382
13140.32.128.0/1840.32.128.1 to 40.32.191.25440.32.191.25516,382
13240.32.192.0/1840.32.192.1 to 40.32.255.25440.32.255.25516,382
13340.33.0.0/1840.33.0.1 to 40.33.63.25440.33.63.25516,382
13440.33.64.0/1840.33.64.1 to 40.33.127.25440.33.127.25516,382
13540.33.128.0/1840.33.128.1 to 40.33.191.25440.33.191.25516,382
13640.33.192.0/1840.33.192.1 to 40.33.255.25440.33.255.25516,382
13740.34.0.0/1840.34.0.1 to 40.34.63.25440.34.63.25516,382
13840.34.64.0/1840.34.64.1 to 40.34.127.25440.34.127.25516,382
13940.34.128.0/1840.34.128.1 to 40.34.191.25440.34.191.25516,382
14040.34.192.0/1840.34.192.1 to 40.34.255.25440.34.255.25516,382
14140.35.0.0/1840.35.0.1 to 40.35.63.25440.35.63.25516,382
14240.35.64.0/1840.35.64.1 to 40.35.127.25440.35.127.25516,382
14340.35.128.0/1840.35.128.1 to 40.35.191.25440.35.191.25516,382
14440.35.192.0/1840.35.192.1 to 40.35.255.25440.35.255.25516,382
14540.36.0.0/1840.36.0.1 to 40.36.63.25440.36.63.25516,382
14640.36.64.0/1840.36.64.1 to 40.36.127.25440.36.127.25516,382
14740.36.128.0/1840.36.128.1 to 40.36.191.25440.36.191.25516,382
14840.36.192.0/1840.36.192.1 to 40.36.255.25440.36.255.25516,382
14940.37.0.0/1840.37.0.1 to 40.37.63.25440.37.63.25516,382
15040.37.64.0/1840.37.64.1 to 40.37.127.25440.37.127.25516,382
15140.37.128.0/1840.37.128.1 to 40.37.191.25440.37.191.25516,382
15240.37.192.0/1840.37.192.1 to 40.37.255.25440.37.255.25516,382
15340.38.0.0/1840.38.0.1 to 40.38.63.25440.38.63.25516,382
15440.38.64.0/1840.38.64.1 to 40.38.127.25440.38.127.25516,382
15540.38.128.0/1840.38.128.1 to 40.38.191.25440.38.191.25516,382
15640.38.192.0/1840.38.192.1 to 40.38.255.25440.38.255.25516,382
15740.39.0.0/1840.39.0.1 to 40.39.63.25440.39.63.25516,382
15840.39.64.0/1840.39.64.1 to 40.39.127.25440.39.127.25516,382
15940.39.128.0/1840.39.128.1 to 40.39.191.25440.39.191.25516,382
16040.39.192.0/1840.39.192.1 to 40.39.255.25440.39.255.25516,382
16140.40.0.0/1840.40.0.1 to 40.40.63.25440.40.63.25516,382
16240.40.64.0/1840.40.64.1 to 40.40.127.25440.40.127.25516,382
16340.40.128.0/1840.40.128.1 to 40.40.191.25440.40.191.25516,382
16440.40.192.0/1840.40.192.1 to 40.40.255.25440.40.255.25516,382
16540.41.0.0/1840.41.0.1 to 40.41.63.25440.41.63.25516,382
16640.41.64.0/1840.41.64.1 to 40.41.127.25440.41.127.25516,382
16740.41.128.0/1840.41.128.1 to 40.41.191.25440.41.191.25516,382
16840.41.192.0/1840.41.192.1 to 40.41.255.25440.41.255.25516,382
16940.42.0.0/1840.42.0.1 to 40.42.63.25440.42.63.25516,382
17040.42.64.0/1840.42.64.1 to 40.42.127.25440.42.127.25516,382
17140.42.128.0/1840.42.128.1 to 40.42.191.25440.42.191.25516,382
17240.42.192.0/1840.42.192.1 to 40.42.255.25440.42.255.25516,382
17340.43.0.0/1840.43.0.1 to 40.43.63.25440.43.63.25516,382
17440.43.64.0/1840.43.64.1 to 40.43.127.25440.43.127.25516,382
17540.43.128.0/1840.43.128.1 to 40.43.191.25440.43.191.25516,382
17640.43.192.0/1840.43.192.1 to 40.43.255.25440.43.255.25516,382
17740.44.0.0/1840.44.0.1 to 40.44.63.25440.44.63.25516,382
17840.44.64.0/1840.44.64.1 to 40.44.127.25440.44.127.25516,382
17940.44.128.0/1840.44.128.1 to 40.44.191.25440.44.191.25516,382
18040.44.192.0/1840.44.192.1 to 40.44.255.25440.44.255.25516,382
18140.45.0.0/1840.45.0.1 to 40.45.63.25440.45.63.25516,382
18240.45.64.0/1840.45.64.1 to 40.45.127.25440.45.127.25516,382
18340.45.128.0/1840.45.128.1 to 40.45.191.25440.45.191.25516,382
18440.45.192.0/1840.45.192.1 to 40.45.255.25440.45.255.25516,382
18540.46.0.0/1840.46.0.1 to 40.46.63.25440.46.63.25516,382
18640.46.64.0/1840.46.64.1 to 40.46.127.25440.46.127.25516,382
18740.46.128.0/1840.46.128.1 to 40.46.191.25440.46.191.25516,382
18840.46.192.0/1840.46.192.1 to 40.46.255.25440.46.255.25516,382
18940.47.0.0/1840.47.0.1 to 40.47.63.25440.47.63.25516,382
19040.47.64.0/1840.47.64.1 to 40.47.127.25440.47.127.25516,382
19140.47.128.0/1840.47.128.1 to 40.47.191.25440.47.191.25516,382
19240.47.192.0/1840.47.192.1 to 40.47.255.25440.47.255.25516,382
19340.48.0.0/1840.48.0.1 to 40.48.63.25440.48.63.25516,382
19440.48.64.0/1840.48.64.1 to 40.48.127.25440.48.127.25516,382
19540.48.128.0/1840.48.128.1 to 40.48.191.25440.48.191.25516,382
19640.48.192.0/1840.48.192.1 to 40.48.255.25440.48.255.25516,382
19740.49.0.0/1840.49.0.1 to 40.49.63.25440.49.63.25516,382
19840.49.64.0/1840.49.64.1 to 40.49.127.25440.49.127.25516,382
19940.49.128.0/1840.49.128.1 to 40.49.191.25440.49.191.25516,382
20040.49.192.0/1840.49.192.1 to 40.49.255.25440.49.255.25516,382
20140.50.0.0/1840.50.0.1 to 40.50.63.25440.50.63.25516,382
20240.50.64.0/1840.50.64.1 to 40.50.127.25440.50.127.25516,382
20340.50.128.0/1840.50.128.1 to 40.50.191.25440.50.191.25516,382
20440.50.192.0/1840.50.192.1 to 40.50.255.25440.50.255.25516,382
20540.51.0.0/1840.51.0.1 to 40.51.63.25440.51.63.25516,382
20640.51.64.0/1840.51.64.1 to 40.51.127.25440.51.127.25516,382
20740.51.128.0/1840.51.128.1 to 40.51.191.25440.51.191.25516,382
20840.51.192.0/1840.51.192.1 to 40.51.255.25440.51.255.25516,382
20940.52.0.0/1840.52.0.1 to 40.52.63.25440.52.63.25516,382
21040.52.64.0/1840.52.64.1 to 40.52.127.25440.52.127.25516,382
21140.52.128.0/1840.52.128.1 to 40.52.191.25440.52.191.25516,382
21240.52.192.0/1840.52.192.1 to 40.52.255.25440.52.255.25516,382
21340.53.0.0/1840.53.0.1 to 40.53.63.25440.53.63.25516,382
21440.53.64.0/1840.53.64.1 to 40.53.127.25440.53.127.25516,382
21540.53.128.0/1840.53.128.1 to 40.53.191.25440.53.191.25516,382
21640.53.192.0/1840.53.192.1 to 40.53.255.25440.53.255.25516,382
21740.54.0.0/1840.54.0.1 to 40.54.63.25440.54.63.25516,382
21840.54.64.0/1840.54.64.1 to 40.54.127.25440.54.127.25516,382
21940.54.128.0/1840.54.128.1 to 40.54.191.25440.54.191.25516,382
22040.54.192.0/1840.54.192.1 to 40.54.255.25440.54.255.25516,382
22140.55.0.0/1840.55.0.1 to 40.55.63.25440.55.63.25516,382
22240.55.64.0/1840.55.64.1 to 40.55.127.25440.55.127.25516,382
22340.55.128.0/1840.55.128.1 to 40.55.191.25440.55.191.25516,382
22440.55.192.0/1840.55.192.1 to 40.55.255.25440.55.255.25516,382
22540.56.0.0/1840.56.0.1 to 40.56.63.25440.56.63.25516,382
22640.56.64.0/1840.56.64.1 to 40.56.127.25440.56.127.25516,382
22740.56.128.0/1840.56.128.1 to 40.56.191.25440.56.191.25516,382
22840.56.192.0/1840.56.192.1 to 40.56.255.25440.56.255.25516,382
22940.57.0.0/1840.57.0.1 to 40.57.63.25440.57.63.25516,382
23040.57.64.0/1840.57.64.1 to 40.57.127.25440.57.127.25516,382
23140.57.128.0/1840.57.128.1 to 40.57.191.25440.57.191.25516,382
23240.57.192.0/1840.57.192.1 to 40.57.255.25440.57.255.25516,382
23340.58.0.0/1840.58.0.1 to 40.58.63.25440.58.63.25516,382
23440.58.64.0/1840.58.64.1 to 40.58.127.25440.58.127.25516,382
23540.58.128.0/1840.58.128.1 to 40.58.191.25440.58.191.25516,382
23640.58.192.0/1840.58.192.1 to 40.58.255.25440.58.255.25516,382
23740.59.0.0/1840.59.0.1 to 40.59.63.25440.59.63.25516,382
23840.59.64.0/1840.59.64.1 to 40.59.127.25440.59.127.25516,382
23940.59.128.0/1840.59.128.1 to 40.59.191.25440.59.191.25516,382
24040.59.192.0/1840.59.192.1 to 40.59.255.25440.59.255.25516,382
24140.60.0.0/1840.60.0.1 to 40.60.63.25440.60.63.25516,382
24240.60.64.0/1840.60.64.1 to 40.60.127.25440.60.127.25516,382
24340.60.128.0/1840.60.128.1 to 40.60.191.25440.60.191.25516,382
24440.60.192.0/1840.60.192.1 to 40.60.255.25440.60.255.25516,382
24540.61.0.0/1840.61.0.1 to 40.61.63.25440.61.63.25516,382
24640.61.64.0/1840.61.64.1 to 40.61.127.25440.61.127.25516,382
24740.61.128.0/1840.61.128.1 to 40.61.191.25440.61.191.25516,382
24840.61.192.0/1840.61.192.1 to 40.61.255.25440.61.255.25516,382
24940.62.0.0/1840.62.0.1 to 40.62.63.25440.62.63.25516,382
25040.62.64.0/1840.62.64.1 to 40.62.127.25440.62.127.25516,382
25140.62.128.0/1840.62.128.1 to 40.62.191.25440.62.191.25516,382
25240.62.192.0/1840.62.192.1 to 40.62.255.25440.62.255.25516,382
25340.63.0.0/1840.63.0.1 to 40.63.63.25440.63.63.25516,382
25440.63.64.0/1840.63.64.1 to 40.63.127.25440.63.127.25516,382
25540.63.128.0/1840.63.128.1 to 40.63.191.25440.63.191.25516,382
25640.63.192.0/1840.63.192.1 to 40.63.255.25440.63.255.25516,382

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.