Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

Computers and devices

Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

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.

Network87.26.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
87.26.0.0
Broadcast address
87.27.255.255
First usable
87.26.0.1
Last usable
87.27.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 571A0000 · Integer 1461321728 to 1461452799
Reverse DNS zones
26.87.in-addr.arpa
27.87.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010111.00011010.00000000.0000000087.26.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01010111.00011010.00000000.0000000087.26.0.0
Broadcast01010111.00011011.11111111.1111111187.27.255.255
Split into smaller subnets/26
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

87.26.0.0/15 makes 2,048 subnets of /26; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
187.26.0.0/2687.26.0.1 to 87.26.0.6287.26.0.6362
287.26.0.64/2687.26.0.65 to 87.26.0.12687.26.0.12762
387.26.0.128/2687.26.0.129 to 87.26.0.19087.26.0.19162
487.26.0.192/2687.26.0.193 to 87.26.0.25487.26.0.25562
587.26.1.0/2687.26.1.1 to 87.26.1.6287.26.1.6362
687.26.1.64/2687.26.1.65 to 87.26.1.12687.26.1.12762
787.26.1.128/2687.26.1.129 to 87.26.1.19087.26.1.19162
887.26.1.192/2687.26.1.193 to 87.26.1.25487.26.1.25562
987.26.2.0/2687.26.2.1 to 87.26.2.6287.26.2.6362
1087.26.2.64/2687.26.2.65 to 87.26.2.12687.26.2.12762
1187.26.2.128/2687.26.2.129 to 87.26.2.19087.26.2.19162
1287.26.2.192/2687.26.2.193 to 87.26.2.25487.26.2.25562
1387.26.3.0/2687.26.3.1 to 87.26.3.6287.26.3.6362
1487.26.3.64/2687.26.3.65 to 87.26.3.12687.26.3.12762
1587.26.3.128/2687.26.3.129 to 87.26.3.19087.26.3.19162
1687.26.3.192/2687.26.3.193 to 87.26.3.25487.26.3.25562
1787.26.4.0/2687.26.4.1 to 87.26.4.6287.26.4.6362
1887.26.4.64/2687.26.4.65 to 87.26.4.12687.26.4.12762
1987.26.4.128/2687.26.4.129 to 87.26.4.19087.26.4.19162
2087.26.4.192/2687.26.4.193 to 87.26.4.25487.26.4.25562
2187.26.5.0/2687.26.5.1 to 87.26.5.6287.26.5.6362
2287.26.5.64/2687.26.5.65 to 87.26.5.12687.26.5.12762
2387.26.5.128/2687.26.5.129 to 87.26.5.19087.26.5.19162
2487.26.5.192/2687.26.5.193 to 87.26.5.25487.26.5.25562
2587.26.6.0/2687.26.6.1 to 87.26.6.6287.26.6.6362
2687.26.6.64/2687.26.6.65 to 87.26.6.12687.26.6.12762
2787.26.6.128/2687.26.6.129 to 87.26.6.19087.26.6.19162
2887.26.6.192/2687.26.6.193 to 87.26.6.25487.26.6.25562
2987.26.7.0/2687.26.7.1 to 87.26.7.6287.26.7.6362
3087.26.7.64/2687.26.7.65 to 87.26.7.12687.26.7.12762
3187.26.7.128/2687.26.7.129 to 87.26.7.19087.26.7.19162
3287.26.7.192/2687.26.7.193 to 87.26.7.25487.26.7.25562
3387.26.8.0/2687.26.8.1 to 87.26.8.6287.26.8.6362
3487.26.8.64/2687.26.8.65 to 87.26.8.12687.26.8.12762
3587.26.8.128/2687.26.8.129 to 87.26.8.19087.26.8.19162
3687.26.8.192/2687.26.8.193 to 87.26.8.25487.26.8.25562
3787.26.9.0/2687.26.9.1 to 87.26.9.6287.26.9.6362
3887.26.9.64/2687.26.9.65 to 87.26.9.12687.26.9.12762
3987.26.9.128/2687.26.9.129 to 87.26.9.19087.26.9.19162
4087.26.9.192/2687.26.9.193 to 87.26.9.25487.26.9.25562
4187.26.10.0/2687.26.10.1 to 87.26.10.6287.26.10.6362
4287.26.10.64/2687.26.10.65 to 87.26.10.12687.26.10.12762
4387.26.10.128/2687.26.10.129 to 87.26.10.19087.26.10.19162
4487.26.10.192/2687.26.10.193 to 87.26.10.25487.26.10.25562
4587.26.11.0/2687.26.11.1 to 87.26.11.6287.26.11.6362
4687.26.11.64/2687.26.11.65 to 87.26.11.12687.26.11.12762
4787.26.11.128/2687.26.11.129 to 87.26.11.19087.26.11.19162
4887.26.11.192/2687.26.11.193 to 87.26.11.25487.26.11.25562
4987.26.12.0/2687.26.12.1 to 87.26.12.6287.26.12.6362
5087.26.12.64/2687.26.12.65 to 87.26.12.12687.26.12.12762
5187.26.12.128/2687.26.12.129 to 87.26.12.19087.26.12.19162
5287.26.12.192/2687.26.12.193 to 87.26.12.25487.26.12.25562
5387.26.13.0/2687.26.13.1 to 87.26.13.6287.26.13.6362
5487.26.13.64/2687.26.13.65 to 87.26.13.12687.26.13.12762
5587.26.13.128/2687.26.13.129 to 87.26.13.19087.26.13.19162
5687.26.13.192/2687.26.13.193 to 87.26.13.25487.26.13.25562
5787.26.14.0/2687.26.14.1 to 87.26.14.6287.26.14.6362
5887.26.14.64/2687.26.14.65 to 87.26.14.12687.26.14.12762
5987.26.14.128/2687.26.14.129 to 87.26.14.19087.26.14.19162
6087.26.14.192/2687.26.14.193 to 87.26.14.25487.26.14.25562
6187.26.15.0/2687.26.15.1 to 87.26.15.6287.26.15.6362
6287.26.15.64/2687.26.15.65 to 87.26.15.12687.26.15.12762
6387.26.15.128/2687.26.15.129 to 87.26.15.19087.26.15.19162
6487.26.15.192/2687.26.15.193 to 87.26.15.25487.26.15.25562
6587.26.16.0/2687.26.16.1 to 87.26.16.6287.26.16.6362
6687.26.16.64/2687.26.16.65 to 87.26.16.12687.26.16.12762
6787.26.16.128/2687.26.16.129 to 87.26.16.19087.26.16.19162
6887.26.16.192/2687.26.16.193 to 87.26.16.25487.26.16.25562
6987.26.17.0/2687.26.17.1 to 87.26.17.6287.26.17.6362
7087.26.17.64/2687.26.17.65 to 87.26.17.12687.26.17.12762
7187.26.17.128/2687.26.17.129 to 87.26.17.19087.26.17.19162
7287.26.17.192/2687.26.17.193 to 87.26.17.25487.26.17.25562
7387.26.18.0/2687.26.18.1 to 87.26.18.6287.26.18.6362
7487.26.18.64/2687.26.18.65 to 87.26.18.12687.26.18.12762
7587.26.18.128/2687.26.18.129 to 87.26.18.19087.26.18.19162
7687.26.18.192/2687.26.18.193 to 87.26.18.25487.26.18.25562
7787.26.19.0/2687.26.19.1 to 87.26.19.6287.26.19.6362
7887.26.19.64/2687.26.19.65 to 87.26.19.12687.26.19.12762
7987.26.19.128/2687.26.19.129 to 87.26.19.19087.26.19.19162
8087.26.19.192/2687.26.19.193 to 87.26.19.25487.26.19.25562
8187.26.20.0/2687.26.20.1 to 87.26.20.6287.26.20.6362
8287.26.20.64/2687.26.20.65 to 87.26.20.12687.26.20.12762
8387.26.20.128/2687.26.20.129 to 87.26.20.19087.26.20.19162
8487.26.20.192/2687.26.20.193 to 87.26.20.25487.26.20.25562
8587.26.21.0/2687.26.21.1 to 87.26.21.6287.26.21.6362
8687.26.21.64/2687.26.21.65 to 87.26.21.12687.26.21.12762
8787.26.21.128/2687.26.21.129 to 87.26.21.19087.26.21.19162
8887.26.21.192/2687.26.21.193 to 87.26.21.25487.26.21.25562
8987.26.22.0/2687.26.22.1 to 87.26.22.6287.26.22.6362
9087.26.22.64/2687.26.22.65 to 87.26.22.12687.26.22.12762
9187.26.22.128/2687.26.22.129 to 87.26.22.19087.26.22.19162
9287.26.22.192/2687.26.22.193 to 87.26.22.25487.26.22.25562
9387.26.23.0/2687.26.23.1 to 87.26.23.6287.26.23.6362
9487.26.23.64/2687.26.23.65 to 87.26.23.12687.26.23.12762
9587.26.23.128/2687.26.23.129 to 87.26.23.19087.26.23.19162
9687.26.23.192/2687.26.23.193 to 87.26.23.25487.26.23.25562
9787.26.24.0/2687.26.24.1 to 87.26.24.6287.26.24.6362
9887.26.24.64/2687.26.24.65 to 87.26.24.12687.26.24.12762
9987.26.24.128/2687.26.24.129 to 87.26.24.19087.26.24.19162
10087.26.24.192/2687.26.24.193 to 87.26.24.25487.26.24.25562
10187.26.25.0/2687.26.25.1 to 87.26.25.6287.26.25.6362
10287.26.25.64/2687.26.25.65 to 87.26.25.12687.26.25.12762
10387.26.25.128/2687.26.25.129 to 87.26.25.19087.26.25.19162
10487.26.25.192/2687.26.25.193 to 87.26.25.25487.26.25.25562
10587.26.26.0/2687.26.26.1 to 87.26.26.6287.26.26.6362
10687.26.26.64/2687.26.26.65 to 87.26.26.12687.26.26.12762
10787.26.26.128/2687.26.26.129 to 87.26.26.19087.26.26.19162
10887.26.26.192/2687.26.26.193 to 87.26.26.25487.26.26.25562
10987.26.27.0/2687.26.27.1 to 87.26.27.6287.26.27.6362
11087.26.27.64/2687.26.27.65 to 87.26.27.12687.26.27.12762
11187.26.27.128/2687.26.27.129 to 87.26.27.19087.26.27.19162
11287.26.27.192/2687.26.27.193 to 87.26.27.25487.26.27.25562
11387.26.28.0/2687.26.28.1 to 87.26.28.6287.26.28.6362
11487.26.28.64/2687.26.28.65 to 87.26.28.12687.26.28.12762
11587.26.28.128/2687.26.28.129 to 87.26.28.19087.26.28.19162
11687.26.28.192/2687.26.28.193 to 87.26.28.25487.26.28.25562
11787.26.29.0/2687.26.29.1 to 87.26.29.6287.26.29.6362
11887.26.29.64/2687.26.29.65 to 87.26.29.12687.26.29.12762
11987.26.29.128/2687.26.29.129 to 87.26.29.19087.26.29.19162
12087.26.29.192/2687.26.29.193 to 87.26.29.25487.26.29.25562
12187.26.30.0/2687.26.30.1 to 87.26.30.6287.26.30.6362
12287.26.30.64/2687.26.30.65 to 87.26.30.12687.26.30.12762
12387.26.30.128/2687.26.30.129 to 87.26.30.19087.26.30.19162
12487.26.30.192/2687.26.30.193 to 87.26.30.25487.26.30.25562
12587.26.31.0/2687.26.31.1 to 87.26.31.6287.26.31.6362
12687.26.31.64/2687.26.31.65 to 87.26.31.12687.26.31.12762
12787.26.31.128/2687.26.31.129 to 87.26.31.19087.26.31.19162
12887.26.31.192/2687.26.31.193 to 87.26.31.25487.26.31.25562
12987.26.32.0/2687.26.32.1 to 87.26.32.6287.26.32.6362
13087.26.32.64/2687.26.32.65 to 87.26.32.12687.26.32.12762
13187.26.32.128/2687.26.32.129 to 87.26.32.19087.26.32.19162
13287.26.32.192/2687.26.32.193 to 87.26.32.25487.26.32.25562
13387.26.33.0/2687.26.33.1 to 87.26.33.6287.26.33.6362
13487.26.33.64/2687.26.33.65 to 87.26.33.12687.26.33.12762
13587.26.33.128/2687.26.33.129 to 87.26.33.19087.26.33.19162
13687.26.33.192/2687.26.33.193 to 87.26.33.25487.26.33.25562
13787.26.34.0/2687.26.34.1 to 87.26.34.6287.26.34.6362
13887.26.34.64/2687.26.34.65 to 87.26.34.12687.26.34.12762
13987.26.34.128/2687.26.34.129 to 87.26.34.19087.26.34.19162
14087.26.34.192/2687.26.34.193 to 87.26.34.25487.26.34.25562
14187.26.35.0/2687.26.35.1 to 87.26.35.6287.26.35.6362
14287.26.35.64/2687.26.35.65 to 87.26.35.12687.26.35.12762
14387.26.35.128/2687.26.35.129 to 87.26.35.19087.26.35.19162
14487.26.35.192/2687.26.35.193 to 87.26.35.25487.26.35.25562
14587.26.36.0/2687.26.36.1 to 87.26.36.6287.26.36.6362
14687.26.36.64/2687.26.36.65 to 87.26.36.12687.26.36.12762
14787.26.36.128/2687.26.36.129 to 87.26.36.19087.26.36.19162
14887.26.36.192/2687.26.36.193 to 87.26.36.25487.26.36.25562
14987.26.37.0/2687.26.37.1 to 87.26.37.6287.26.37.6362
15087.26.37.64/2687.26.37.65 to 87.26.37.12687.26.37.12762
15187.26.37.128/2687.26.37.129 to 87.26.37.19087.26.37.19162
15287.26.37.192/2687.26.37.193 to 87.26.37.25487.26.37.25562
15387.26.38.0/2687.26.38.1 to 87.26.38.6287.26.38.6362
15487.26.38.64/2687.26.38.65 to 87.26.38.12687.26.38.12762
15587.26.38.128/2687.26.38.129 to 87.26.38.19087.26.38.19162
15687.26.38.192/2687.26.38.193 to 87.26.38.25487.26.38.25562
15787.26.39.0/2687.26.39.1 to 87.26.39.6287.26.39.6362
15887.26.39.64/2687.26.39.65 to 87.26.39.12687.26.39.12762
15987.26.39.128/2687.26.39.129 to 87.26.39.19087.26.39.19162
16087.26.39.192/2687.26.39.193 to 87.26.39.25487.26.39.25562
16187.26.40.0/2687.26.40.1 to 87.26.40.6287.26.40.6362
16287.26.40.64/2687.26.40.65 to 87.26.40.12687.26.40.12762
16387.26.40.128/2687.26.40.129 to 87.26.40.19087.26.40.19162
16487.26.40.192/2687.26.40.193 to 87.26.40.25487.26.40.25562
16587.26.41.0/2687.26.41.1 to 87.26.41.6287.26.41.6362
16687.26.41.64/2687.26.41.65 to 87.26.41.12687.26.41.12762
16787.26.41.128/2687.26.41.129 to 87.26.41.19087.26.41.19162
16887.26.41.192/2687.26.41.193 to 87.26.41.25487.26.41.25562
16987.26.42.0/2687.26.42.1 to 87.26.42.6287.26.42.6362
17087.26.42.64/2687.26.42.65 to 87.26.42.12687.26.42.12762
17187.26.42.128/2687.26.42.129 to 87.26.42.19087.26.42.19162
17287.26.42.192/2687.26.42.193 to 87.26.42.25487.26.42.25562
17387.26.43.0/2687.26.43.1 to 87.26.43.6287.26.43.6362
17487.26.43.64/2687.26.43.65 to 87.26.43.12687.26.43.12762
17587.26.43.128/2687.26.43.129 to 87.26.43.19087.26.43.19162
17687.26.43.192/2687.26.43.193 to 87.26.43.25487.26.43.25562
17787.26.44.0/2687.26.44.1 to 87.26.44.6287.26.44.6362
17887.26.44.64/2687.26.44.65 to 87.26.44.12687.26.44.12762
17987.26.44.128/2687.26.44.129 to 87.26.44.19087.26.44.19162
18087.26.44.192/2687.26.44.193 to 87.26.44.25487.26.44.25562
18187.26.45.0/2687.26.45.1 to 87.26.45.6287.26.45.6362
18287.26.45.64/2687.26.45.65 to 87.26.45.12687.26.45.12762
18387.26.45.128/2687.26.45.129 to 87.26.45.19087.26.45.19162
18487.26.45.192/2687.26.45.193 to 87.26.45.25487.26.45.25562
18587.26.46.0/2687.26.46.1 to 87.26.46.6287.26.46.6362
18687.26.46.64/2687.26.46.65 to 87.26.46.12687.26.46.12762
18787.26.46.128/2687.26.46.129 to 87.26.46.19087.26.46.19162
18887.26.46.192/2687.26.46.193 to 87.26.46.25487.26.46.25562
18987.26.47.0/2687.26.47.1 to 87.26.47.6287.26.47.6362
19087.26.47.64/2687.26.47.65 to 87.26.47.12687.26.47.12762
19187.26.47.128/2687.26.47.129 to 87.26.47.19087.26.47.19162
19287.26.47.192/2687.26.47.193 to 87.26.47.25487.26.47.25562
19387.26.48.0/2687.26.48.1 to 87.26.48.6287.26.48.6362
19487.26.48.64/2687.26.48.65 to 87.26.48.12687.26.48.12762
19587.26.48.128/2687.26.48.129 to 87.26.48.19087.26.48.19162
19687.26.48.192/2687.26.48.193 to 87.26.48.25487.26.48.25562
19787.26.49.0/2687.26.49.1 to 87.26.49.6287.26.49.6362
19887.26.49.64/2687.26.49.65 to 87.26.49.12687.26.49.12762
19987.26.49.128/2687.26.49.129 to 87.26.49.19087.26.49.19162
20087.26.49.192/2687.26.49.193 to 87.26.49.25487.26.49.25562
20187.26.50.0/2687.26.50.1 to 87.26.50.6287.26.50.6362
20287.26.50.64/2687.26.50.65 to 87.26.50.12687.26.50.12762
20387.26.50.128/2687.26.50.129 to 87.26.50.19087.26.50.19162
20487.26.50.192/2687.26.50.193 to 87.26.50.25487.26.50.25562
20587.26.51.0/2687.26.51.1 to 87.26.51.6287.26.51.6362
20687.26.51.64/2687.26.51.65 to 87.26.51.12687.26.51.12762
20787.26.51.128/2687.26.51.129 to 87.26.51.19087.26.51.19162
20887.26.51.192/2687.26.51.193 to 87.26.51.25487.26.51.25562
20987.26.52.0/2687.26.52.1 to 87.26.52.6287.26.52.6362
21087.26.52.64/2687.26.52.65 to 87.26.52.12687.26.52.12762
21187.26.52.128/2687.26.52.129 to 87.26.52.19087.26.52.19162
21287.26.52.192/2687.26.52.193 to 87.26.52.25487.26.52.25562
21387.26.53.0/2687.26.53.1 to 87.26.53.6287.26.53.6362
21487.26.53.64/2687.26.53.65 to 87.26.53.12687.26.53.12762
21587.26.53.128/2687.26.53.129 to 87.26.53.19087.26.53.19162
21687.26.53.192/2687.26.53.193 to 87.26.53.25487.26.53.25562
21787.26.54.0/2687.26.54.1 to 87.26.54.6287.26.54.6362
21887.26.54.64/2687.26.54.65 to 87.26.54.12687.26.54.12762
21987.26.54.128/2687.26.54.129 to 87.26.54.19087.26.54.19162
22087.26.54.192/2687.26.54.193 to 87.26.54.25487.26.54.25562
22187.26.55.0/2687.26.55.1 to 87.26.55.6287.26.55.6362
22287.26.55.64/2687.26.55.65 to 87.26.55.12687.26.55.12762
22387.26.55.128/2687.26.55.129 to 87.26.55.19087.26.55.19162
22487.26.55.192/2687.26.55.193 to 87.26.55.25487.26.55.25562
22587.26.56.0/2687.26.56.1 to 87.26.56.6287.26.56.6362
22687.26.56.64/2687.26.56.65 to 87.26.56.12687.26.56.12762
22787.26.56.128/2687.26.56.129 to 87.26.56.19087.26.56.19162
22887.26.56.192/2687.26.56.193 to 87.26.56.25487.26.56.25562
22987.26.57.0/2687.26.57.1 to 87.26.57.6287.26.57.6362
23087.26.57.64/2687.26.57.65 to 87.26.57.12687.26.57.12762
23187.26.57.128/2687.26.57.129 to 87.26.57.19087.26.57.19162
23287.26.57.192/2687.26.57.193 to 87.26.57.25487.26.57.25562
23387.26.58.0/2687.26.58.1 to 87.26.58.6287.26.58.6362
23487.26.58.64/2687.26.58.65 to 87.26.58.12687.26.58.12762
23587.26.58.128/2687.26.58.129 to 87.26.58.19087.26.58.19162
23687.26.58.192/2687.26.58.193 to 87.26.58.25487.26.58.25562
23787.26.59.0/2687.26.59.1 to 87.26.59.6287.26.59.6362
23887.26.59.64/2687.26.59.65 to 87.26.59.12687.26.59.12762
23987.26.59.128/2687.26.59.129 to 87.26.59.19087.26.59.19162
24087.26.59.192/2687.26.59.193 to 87.26.59.25487.26.59.25562
24187.26.60.0/2687.26.60.1 to 87.26.60.6287.26.60.6362
24287.26.60.64/2687.26.60.65 to 87.26.60.12687.26.60.12762
24387.26.60.128/2687.26.60.129 to 87.26.60.19087.26.60.19162
24487.26.60.192/2687.26.60.193 to 87.26.60.25487.26.60.25562
24587.26.61.0/2687.26.61.1 to 87.26.61.6287.26.61.6362
24687.26.61.64/2687.26.61.65 to 87.26.61.12687.26.61.12762
24787.26.61.128/2687.26.61.129 to 87.26.61.19087.26.61.19162
24887.26.61.192/2687.26.61.193 to 87.26.61.25487.26.61.25562
24987.26.62.0/2687.26.62.1 to 87.26.62.6287.26.62.6362
25087.26.62.64/2687.26.62.65 to 87.26.62.12687.26.62.12762
25187.26.62.128/2687.26.62.129 to 87.26.62.19087.26.62.19162
25287.26.62.192/2687.26.62.193 to 87.26.62.25487.26.62.25562
25387.26.63.0/2687.26.63.1 to 87.26.63.6287.26.63.6362
25487.26.63.64/2687.26.63.65 to 87.26.63.12687.26.63.12762
25587.26.63.128/2687.26.63.129 to 87.26.63.19087.26.63.19162
25687.26.63.192/2687.26.63.193 to 87.26.63.25487.26.63.25562

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.