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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.

Network27.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
27.0.0.0
Broadcast address
27.255.255.255
First usable
27.0.0.1
Last usable
27.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 1B000000 · Integer 452984832 to 469762047
Reverse DNS zone
27.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011011..00000000.00000000.0000000027.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00011011..00000000.00000000.0000000027.0.0.0
Broadcast00011011..11111111.11111111.1111111127.255.255.255
Split into smaller subnets/18
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

27.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
127.0.0.0/1827.0.0.1 to 27.0.63.25427.0.63.25516,382
227.0.64.0/1827.0.64.1 to 27.0.127.25427.0.127.25516,382
327.0.128.0/1827.0.128.1 to 27.0.191.25427.0.191.25516,382
427.0.192.0/1827.0.192.1 to 27.0.255.25427.0.255.25516,382
527.1.0.0/1827.1.0.1 to 27.1.63.25427.1.63.25516,382
627.1.64.0/1827.1.64.1 to 27.1.127.25427.1.127.25516,382
727.1.128.0/1827.1.128.1 to 27.1.191.25427.1.191.25516,382
827.1.192.0/1827.1.192.1 to 27.1.255.25427.1.255.25516,382
927.2.0.0/1827.2.0.1 to 27.2.63.25427.2.63.25516,382
1027.2.64.0/1827.2.64.1 to 27.2.127.25427.2.127.25516,382
1127.2.128.0/1827.2.128.1 to 27.2.191.25427.2.191.25516,382
1227.2.192.0/1827.2.192.1 to 27.2.255.25427.2.255.25516,382
1327.3.0.0/1827.3.0.1 to 27.3.63.25427.3.63.25516,382
1427.3.64.0/1827.3.64.1 to 27.3.127.25427.3.127.25516,382
1527.3.128.0/1827.3.128.1 to 27.3.191.25427.3.191.25516,382
1627.3.192.0/1827.3.192.1 to 27.3.255.25427.3.255.25516,382
1727.4.0.0/1827.4.0.1 to 27.4.63.25427.4.63.25516,382
1827.4.64.0/1827.4.64.1 to 27.4.127.25427.4.127.25516,382
1927.4.128.0/1827.4.128.1 to 27.4.191.25427.4.191.25516,382
2027.4.192.0/1827.4.192.1 to 27.4.255.25427.4.255.25516,382
2127.5.0.0/1827.5.0.1 to 27.5.63.25427.5.63.25516,382
2227.5.64.0/1827.5.64.1 to 27.5.127.25427.5.127.25516,382
2327.5.128.0/1827.5.128.1 to 27.5.191.25427.5.191.25516,382
2427.5.192.0/1827.5.192.1 to 27.5.255.25427.5.255.25516,382
2527.6.0.0/1827.6.0.1 to 27.6.63.25427.6.63.25516,382
2627.6.64.0/1827.6.64.1 to 27.6.127.25427.6.127.25516,382
2727.6.128.0/1827.6.128.1 to 27.6.191.25427.6.191.25516,382
2827.6.192.0/1827.6.192.1 to 27.6.255.25427.6.255.25516,382
2927.7.0.0/1827.7.0.1 to 27.7.63.25427.7.63.25516,382
3027.7.64.0/1827.7.64.1 to 27.7.127.25427.7.127.25516,382
3127.7.128.0/1827.7.128.1 to 27.7.191.25427.7.191.25516,382
3227.7.192.0/1827.7.192.1 to 27.7.255.25427.7.255.25516,382
3327.8.0.0/1827.8.0.1 to 27.8.63.25427.8.63.25516,382
3427.8.64.0/1827.8.64.1 to 27.8.127.25427.8.127.25516,382
3527.8.128.0/1827.8.128.1 to 27.8.191.25427.8.191.25516,382
3627.8.192.0/1827.8.192.1 to 27.8.255.25427.8.255.25516,382
3727.9.0.0/1827.9.0.1 to 27.9.63.25427.9.63.25516,382
3827.9.64.0/1827.9.64.1 to 27.9.127.25427.9.127.25516,382
3927.9.128.0/1827.9.128.1 to 27.9.191.25427.9.191.25516,382
4027.9.192.0/1827.9.192.1 to 27.9.255.25427.9.255.25516,382
4127.10.0.0/1827.10.0.1 to 27.10.63.25427.10.63.25516,382
4227.10.64.0/1827.10.64.1 to 27.10.127.25427.10.127.25516,382
4327.10.128.0/1827.10.128.1 to 27.10.191.25427.10.191.25516,382
4427.10.192.0/1827.10.192.1 to 27.10.255.25427.10.255.25516,382
4527.11.0.0/1827.11.0.1 to 27.11.63.25427.11.63.25516,382
4627.11.64.0/1827.11.64.1 to 27.11.127.25427.11.127.25516,382
4727.11.128.0/1827.11.128.1 to 27.11.191.25427.11.191.25516,382
4827.11.192.0/1827.11.192.1 to 27.11.255.25427.11.255.25516,382
4927.12.0.0/1827.12.0.1 to 27.12.63.25427.12.63.25516,382
5027.12.64.0/1827.12.64.1 to 27.12.127.25427.12.127.25516,382
5127.12.128.0/1827.12.128.1 to 27.12.191.25427.12.191.25516,382
5227.12.192.0/1827.12.192.1 to 27.12.255.25427.12.255.25516,382
5327.13.0.0/1827.13.0.1 to 27.13.63.25427.13.63.25516,382
5427.13.64.0/1827.13.64.1 to 27.13.127.25427.13.127.25516,382
5527.13.128.0/1827.13.128.1 to 27.13.191.25427.13.191.25516,382
5627.13.192.0/1827.13.192.1 to 27.13.255.25427.13.255.25516,382
5727.14.0.0/1827.14.0.1 to 27.14.63.25427.14.63.25516,382
5827.14.64.0/1827.14.64.1 to 27.14.127.25427.14.127.25516,382
5927.14.128.0/1827.14.128.1 to 27.14.191.25427.14.191.25516,382
6027.14.192.0/1827.14.192.1 to 27.14.255.25427.14.255.25516,382
6127.15.0.0/1827.15.0.1 to 27.15.63.25427.15.63.25516,382
6227.15.64.0/1827.15.64.1 to 27.15.127.25427.15.127.25516,382
6327.15.128.0/1827.15.128.1 to 27.15.191.25427.15.191.25516,382
6427.15.192.0/1827.15.192.1 to 27.15.255.25427.15.255.25516,382
6527.16.0.0/1827.16.0.1 to 27.16.63.25427.16.63.25516,382
6627.16.64.0/1827.16.64.1 to 27.16.127.25427.16.127.25516,382
6727.16.128.0/1827.16.128.1 to 27.16.191.25427.16.191.25516,382
6827.16.192.0/1827.16.192.1 to 27.16.255.25427.16.255.25516,382
6927.17.0.0/1827.17.0.1 to 27.17.63.25427.17.63.25516,382
7027.17.64.0/1827.17.64.1 to 27.17.127.25427.17.127.25516,382
7127.17.128.0/1827.17.128.1 to 27.17.191.25427.17.191.25516,382
7227.17.192.0/1827.17.192.1 to 27.17.255.25427.17.255.25516,382
7327.18.0.0/1827.18.0.1 to 27.18.63.25427.18.63.25516,382
7427.18.64.0/1827.18.64.1 to 27.18.127.25427.18.127.25516,382
7527.18.128.0/1827.18.128.1 to 27.18.191.25427.18.191.25516,382
7627.18.192.0/1827.18.192.1 to 27.18.255.25427.18.255.25516,382
7727.19.0.0/1827.19.0.1 to 27.19.63.25427.19.63.25516,382
7827.19.64.0/1827.19.64.1 to 27.19.127.25427.19.127.25516,382
7927.19.128.0/1827.19.128.1 to 27.19.191.25427.19.191.25516,382
8027.19.192.0/1827.19.192.1 to 27.19.255.25427.19.255.25516,382
8127.20.0.0/1827.20.0.1 to 27.20.63.25427.20.63.25516,382
8227.20.64.0/1827.20.64.1 to 27.20.127.25427.20.127.25516,382
8327.20.128.0/1827.20.128.1 to 27.20.191.25427.20.191.25516,382
8427.20.192.0/1827.20.192.1 to 27.20.255.25427.20.255.25516,382
8527.21.0.0/1827.21.0.1 to 27.21.63.25427.21.63.25516,382
8627.21.64.0/1827.21.64.1 to 27.21.127.25427.21.127.25516,382
8727.21.128.0/1827.21.128.1 to 27.21.191.25427.21.191.25516,382
8827.21.192.0/1827.21.192.1 to 27.21.255.25427.21.255.25516,382
8927.22.0.0/1827.22.0.1 to 27.22.63.25427.22.63.25516,382
9027.22.64.0/1827.22.64.1 to 27.22.127.25427.22.127.25516,382
9127.22.128.0/1827.22.128.1 to 27.22.191.25427.22.191.25516,382
9227.22.192.0/1827.22.192.1 to 27.22.255.25427.22.255.25516,382
9327.23.0.0/1827.23.0.1 to 27.23.63.25427.23.63.25516,382
9427.23.64.0/1827.23.64.1 to 27.23.127.25427.23.127.25516,382
9527.23.128.0/1827.23.128.1 to 27.23.191.25427.23.191.25516,382
9627.23.192.0/1827.23.192.1 to 27.23.255.25427.23.255.25516,382
9727.24.0.0/1827.24.0.1 to 27.24.63.25427.24.63.25516,382
9827.24.64.0/1827.24.64.1 to 27.24.127.25427.24.127.25516,382
9927.24.128.0/1827.24.128.1 to 27.24.191.25427.24.191.25516,382
10027.24.192.0/1827.24.192.1 to 27.24.255.25427.24.255.25516,382
10127.25.0.0/1827.25.0.1 to 27.25.63.25427.25.63.25516,382
10227.25.64.0/1827.25.64.1 to 27.25.127.25427.25.127.25516,382
10327.25.128.0/1827.25.128.1 to 27.25.191.25427.25.191.25516,382
10427.25.192.0/1827.25.192.1 to 27.25.255.25427.25.255.25516,382
10527.26.0.0/1827.26.0.1 to 27.26.63.25427.26.63.25516,382
10627.26.64.0/1827.26.64.1 to 27.26.127.25427.26.127.25516,382
10727.26.128.0/1827.26.128.1 to 27.26.191.25427.26.191.25516,382
10827.26.192.0/1827.26.192.1 to 27.26.255.25427.26.255.25516,382
10927.27.0.0/1827.27.0.1 to 27.27.63.25427.27.63.25516,382
11027.27.64.0/1827.27.64.1 to 27.27.127.25427.27.127.25516,382
11127.27.128.0/1827.27.128.1 to 27.27.191.25427.27.191.25516,382
11227.27.192.0/1827.27.192.1 to 27.27.255.25427.27.255.25516,382
11327.28.0.0/1827.28.0.1 to 27.28.63.25427.28.63.25516,382
11427.28.64.0/1827.28.64.1 to 27.28.127.25427.28.127.25516,382
11527.28.128.0/1827.28.128.1 to 27.28.191.25427.28.191.25516,382
11627.28.192.0/1827.28.192.1 to 27.28.255.25427.28.255.25516,382
11727.29.0.0/1827.29.0.1 to 27.29.63.25427.29.63.25516,382
11827.29.64.0/1827.29.64.1 to 27.29.127.25427.29.127.25516,382
11927.29.128.0/1827.29.128.1 to 27.29.191.25427.29.191.25516,382
12027.29.192.0/1827.29.192.1 to 27.29.255.25427.29.255.25516,382
12127.30.0.0/1827.30.0.1 to 27.30.63.25427.30.63.25516,382
12227.30.64.0/1827.30.64.1 to 27.30.127.25427.30.127.25516,382
12327.30.128.0/1827.30.128.1 to 27.30.191.25427.30.191.25516,382
12427.30.192.0/1827.30.192.1 to 27.30.255.25427.30.255.25516,382
12527.31.0.0/1827.31.0.1 to 27.31.63.25427.31.63.25516,382
12627.31.64.0/1827.31.64.1 to 27.31.127.25427.31.127.25516,382
12727.31.128.0/1827.31.128.1 to 27.31.191.25427.31.191.25516,382
12827.31.192.0/1827.31.192.1 to 27.31.255.25427.31.255.25516,382
12927.32.0.0/1827.32.0.1 to 27.32.63.25427.32.63.25516,382
13027.32.64.0/1827.32.64.1 to 27.32.127.25427.32.127.25516,382
13127.32.128.0/1827.32.128.1 to 27.32.191.25427.32.191.25516,382
13227.32.192.0/1827.32.192.1 to 27.32.255.25427.32.255.25516,382
13327.33.0.0/1827.33.0.1 to 27.33.63.25427.33.63.25516,382
13427.33.64.0/1827.33.64.1 to 27.33.127.25427.33.127.25516,382
13527.33.128.0/1827.33.128.1 to 27.33.191.25427.33.191.25516,382
13627.33.192.0/1827.33.192.1 to 27.33.255.25427.33.255.25516,382
13727.34.0.0/1827.34.0.1 to 27.34.63.25427.34.63.25516,382
13827.34.64.0/1827.34.64.1 to 27.34.127.25427.34.127.25516,382
13927.34.128.0/1827.34.128.1 to 27.34.191.25427.34.191.25516,382
14027.34.192.0/1827.34.192.1 to 27.34.255.25427.34.255.25516,382
14127.35.0.0/1827.35.0.1 to 27.35.63.25427.35.63.25516,382
14227.35.64.0/1827.35.64.1 to 27.35.127.25427.35.127.25516,382
14327.35.128.0/1827.35.128.1 to 27.35.191.25427.35.191.25516,382
14427.35.192.0/1827.35.192.1 to 27.35.255.25427.35.255.25516,382
14527.36.0.0/1827.36.0.1 to 27.36.63.25427.36.63.25516,382
14627.36.64.0/1827.36.64.1 to 27.36.127.25427.36.127.25516,382
14727.36.128.0/1827.36.128.1 to 27.36.191.25427.36.191.25516,382
14827.36.192.0/1827.36.192.1 to 27.36.255.25427.36.255.25516,382
14927.37.0.0/1827.37.0.1 to 27.37.63.25427.37.63.25516,382
15027.37.64.0/1827.37.64.1 to 27.37.127.25427.37.127.25516,382
15127.37.128.0/1827.37.128.1 to 27.37.191.25427.37.191.25516,382
15227.37.192.0/1827.37.192.1 to 27.37.255.25427.37.255.25516,382
15327.38.0.0/1827.38.0.1 to 27.38.63.25427.38.63.25516,382
15427.38.64.0/1827.38.64.1 to 27.38.127.25427.38.127.25516,382
15527.38.128.0/1827.38.128.1 to 27.38.191.25427.38.191.25516,382
15627.38.192.0/1827.38.192.1 to 27.38.255.25427.38.255.25516,382
15727.39.0.0/1827.39.0.1 to 27.39.63.25427.39.63.25516,382
15827.39.64.0/1827.39.64.1 to 27.39.127.25427.39.127.25516,382
15927.39.128.0/1827.39.128.1 to 27.39.191.25427.39.191.25516,382
16027.39.192.0/1827.39.192.1 to 27.39.255.25427.39.255.25516,382
16127.40.0.0/1827.40.0.1 to 27.40.63.25427.40.63.25516,382
16227.40.64.0/1827.40.64.1 to 27.40.127.25427.40.127.25516,382
16327.40.128.0/1827.40.128.1 to 27.40.191.25427.40.191.25516,382
16427.40.192.0/1827.40.192.1 to 27.40.255.25427.40.255.25516,382
16527.41.0.0/1827.41.0.1 to 27.41.63.25427.41.63.25516,382
16627.41.64.0/1827.41.64.1 to 27.41.127.25427.41.127.25516,382
16727.41.128.0/1827.41.128.1 to 27.41.191.25427.41.191.25516,382
16827.41.192.0/1827.41.192.1 to 27.41.255.25427.41.255.25516,382
16927.42.0.0/1827.42.0.1 to 27.42.63.25427.42.63.25516,382
17027.42.64.0/1827.42.64.1 to 27.42.127.25427.42.127.25516,382
17127.42.128.0/1827.42.128.1 to 27.42.191.25427.42.191.25516,382
17227.42.192.0/1827.42.192.1 to 27.42.255.25427.42.255.25516,382
17327.43.0.0/1827.43.0.1 to 27.43.63.25427.43.63.25516,382
17427.43.64.0/1827.43.64.1 to 27.43.127.25427.43.127.25516,382
17527.43.128.0/1827.43.128.1 to 27.43.191.25427.43.191.25516,382
17627.43.192.0/1827.43.192.1 to 27.43.255.25427.43.255.25516,382
17727.44.0.0/1827.44.0.1 to 27.44.63.25427.44.63.25516,382
17827.44.64.0/1827.44.64.1 to 27.44.127.25427.44.127.25516,382
17927.44.128.0/1827.44.128.1 to 27.44.191.25427.44.191.25516,382
18027.44.192.0/1827.44.192.1 to 27.44.255.25427.44.255.25516,382
18127.45.0.0/1827.45.0.1 to 27.45.63.25427.45.63.25516,382
18227.45.64.0/1827.45.64.1 to 27.45.127.25427.45.127.25516,382
18327.45.128.0/1827.45.128.1 to 27.45.191.25427.45.191.25516,382
18427.45.192.0/1827.45.192.1 to 27.45.255.25427.45.255.25516,382
18527.46.0.0/1827.46.0.1 to 27.46.63.25427.46.63.25516,382
18627.46.64.0/1827.46.64.1 to 27.46.127.25427.46.127.25516,382
18727.46.128.0/1827.46.128.1 to 27.46.191.25427.46.191.25516,382
18827.46.192.0/1827.46.192.1 to 27.46.255.25427.46.255.25516,382
18927.47.0.0/1827.47.0.1 to 27.47.63.25427.47.63.25516,382
19027.47.64.0/1827.47.64.1 to 27.47.127.25427.47.127.25516,382
19127.47.128.0/1827.47.128.1 to 27.47.191.25427.47.191.25516,382
19227.47.192.0/1827.47.192.1 to 27.47.255.25427.47.255.25516,382
19327.48.0.0/1827.48.0.1 to 27.48.63.25427.48.63.25516,382
19427.48.64.0/1827.48.64.1 to 27.48.127.25427.48.127.25516,382
19527.48.128.0/1827.48.128.1 to 27.48.191.25427.48.191.25516,382
19627.48.192.0/1827.48.192.1 to 27.48.255.25427.48.255.25516,382
19727.49.0.0/1827.49.0.1 to 27.49.63.25427.49.63.25516,382
19827.49.64.0/1827.49.64.1 to 27.49.127.25427.49.127.25516,382
19927.49.128.0/1827.49.128.1 to 27.49.191.25427.49.191.25516,382
20027.49.192.0/1827.49.192.1 to 27.49.255.25427.49.255.25516,382
20127.50.0.0/1827.50.0.1 to 27.50.63.25427.50.63.25516,382
20227.50.64.0/1827.50.64.1 to 27.50.127.25427.50.127.25516,382
20327.50.128.0/1827.50.128.1 to 27.50.191.25427.50.191.25516,382
20427.50.192.0/1827.50.192.1 to 27.50.255.25427.50.255.25516,382
20527.51.0.0/1827.51.0.1 to 27.51.63.25427.51.63.25516,382
20627.51.64.0/1827.51.64.1 to 27.51.127.25427.51.127.25516,382
20727.51.128.0/1827.51.128.1 to 27.51.191.25427.51.191.25516,382
20827.51.192.0/1827.51.192.1 to 27.51.255.25427.51.255.25516,382
20927.52.0.0/1827.52.0.1 to 27.52.63.25427.52.63.25516,382
21027.52.64.0/1827.52.64.1 to 27.52.127.25427.52.127.25516,382
21127.52.128.0/1827.52.128.1 to 27.52.191.25427.52.191.25516,382
21227.52.192.0/1827.52.192.1 to 27.52.255.25427.52.255.25516,382
21327.53.0.0/1827.53.0.1 to 27.53.63.25427.53.63.25516,382
21427.53.64.0/1827.53.64.1 to 27.53.127.25427.53.127.25516,382
21527.53.128.0/1827.53.128.1 to 27.53.191.25427.53.191.25516,382
21627.53.192.0/1827.53.192.1 to 27.53.255.25427.53.255.25516,382
21727.54.0.0/1827.54.0.1 to 27.54.63.25427.54.63.25516,382
21827.54.64.0/1827.54.64.1 to 27.54.127.25427.54.127.25516,382
21927.54.128.0/1827.54.128.1 to 27.54.191.25427.54.191.25516,382
22027.54.192.0/1827.54.192.1 to 27.54.255.25427.54.255.25516,382
22127.55.0.0/1827.55.0.1 to 27.55.63.25427.55.63.25516,382
22227.55.64.0/1827.55.64.1 to 27.55.127.25427.55.127.25516,382
22327.55.128.0/1827.55.128.1 to 27.55.191.25427.55.191.25516,382
22427.55.192.0/1827.55.192.1 to 27.55.255.25427.55.255.25516,382
22527.56.0.0/1827.56.0.1 to 27.56.63.25427.56.63.25516,382
22627.56.64.0/1827.56.64.1 to 27.56.127.25427.56.127.25516,382
22727.56.128.0/1827.56.128.1 to 27.56.191.25427.56.191.25516,382
22827.56.192.0/1827.56.192.1 to 27.56.255.25427.56.255.25516,382
22927.57.0.0/1827.57.0.1 to 27.57.63.25427.57.63.25516,382
23027.57.64.0/1827.57.64.1 to 27.57.127.25427.57.127.25516,382
23127.57.128.0/1827.57.128.1 to 27.57.191.25427.57.191.25516,382
23227.57.192.0/1827.57.192.1 to 27.57.255.25427.57.255.25516,382
23327.58.0.0/1827.58.0.1 to 27.58.63.25427.58.63.25516,382
23427.58.64.0/1827.58.64.1 to 27.58.127.25427.58.127.25516,382
23527.58.128.0/1827.58.128.1 to 27.58.191.25427.58.191.25516,382
23627.58.192.0/1827.58.192.1 to 27.58.255.25427.58.255.25516,382
23727.59.0.0/1827.59.0.1 to 27.59.63.25427.59.63.25516,382
23827.59.64.0/1827.59.64.1 to 27.59.127.25427.59.127.25516,382
23927.59.128.0/1827.59.128.1 to 27.59.191.25427.59.191.25516,382
24027.59.192.0/1827.59.192.1 to 27.59.255.25427.59.255.25516,382
24127.60.0.0/1827.60.0.1 to 27.60.63.25427.60.63.25516,382
24227.60.64.0/1827.60.64.1 to 27.60.127.25427.60.127.25516,382
24327.60.128.0/1827.60.128.1 to 27.60.191.25427.60.191.25516,382
24427.60.192.0/1827.60.192.1 to 27.60.255.25427.60.255.25516,382
24527.61.0.0/1827.61.0.1 to 27.61.63.25427.61.63.25516,382
24627.61.64.0/1827.61.64.1 to 27.61.127.25427.61.127.25516,382
24727.61.128.0/1827.61.128.1 to 27.61.191.25427.61.191.25516,382
24827.61.192.0/1827.61.192.1 to 27.61.255.25427.61.255.25516,382
24927.62.0.0/1827.62.0.1 to 27.62.63.25427.62.63.25516,382
25027.62.64.0/1827.62.64.1 to 27.62.127.25427.62.127.25516,382
25127.62.128.0/1827.62.128.1 to 27.62.191.25427.62.191.25516,382
25227.62.192.0/1827.62.192.1 to 27.62.255.25427.62.255.25516,382
25327.63.0.0/1827.63.0.1 to 27.63.63.25427.63.63.25516,382
25427.63.64.0/1827.63.64.1 to 27.63.127.25427.63.127.25516,382
25527.63.128.0/1827.63.128.1 to 27.63.191.25427.63.191.25516,382
25627.63.192.0/1827.63.192.1 to 27.63.255.25427.63.255.25516,382

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.