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.

Network80.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
80.0.0.0
Broadcast address
83.255.255.255
First usable
80.0.0.1
Last usable
83.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
A (default /8)
As numbers
Hex 50000000 · Integer 1342177280 to 1409286143
Reverse DNS zones
80.in-addr.arpa
81.in-addr.arpa
82.in-addr.arpa
83.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010000.00000000.00000000.0000000080.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network01010000.00000000.00000000.0000000080.0.0.0
Broadcast01010011.11111111.11111111.1111111183.255.255.255
Split into smaller subnets/18
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

80.0.0.0/6 makes 4,096 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.0.0.0/1880.0.0.1 to 80.0.63.25480.0.63.25516,382
280.0.64.0/1880.0.64.1 to 80.0.127.25480.0.127.25516,382
380.0.128.0/1880.0.128.1 to 80.0.191.25480.0.191.25516,382
480.0.192.0/1880.0.192.1 to 80.0.255.25480.0.255.25516,382
580.1.0.0/1880.1.0.1 to 80.1.63.25480.1.63.25516,382
680.1.64.0/1880.1.64.1 to 80.1.127.25480.1.127.25516,382
780.1.128.0/1880.1.128.1 to 80.1.191.25480.1.191.25516,382
880.1.192.0/1880.1.192.1 to 80.1.255.25480.1.255.25516,382
980.2.0.0/1880.2.0.1 to 80.2.63.25480.2.63.25516,382
1080.2.64.0/1880.2.64.1 to 80.2.127.25480.2.127.25516,382
1180.2.128.0/1880.2.128.1 to 80.2.191.25480.2.191.25516,382
1280.2.192.0/1880.2.192.1 to 80.2.255.25480.2.255.25516,382
1380.3.0.0/1880.3.0.1 to 80.3.63.25480.3.63.25516,382
1480.3.64.0/1880.3.64.1 to 80.3.127.25480.3.127.25516,382
1580.3.128.0/1880.3.128.1 to 80.3.191.25480.3.191.25516,382
1680.3.192.0/1880.3.192.1 to 80.3.255.25480.3.255.25516,382
1780.4.0.0/1880.4.0.1 to 80.4.63.25480.4.63.25516,382
1880.4.64.0/1880.4.64.1 to 80.4.127.25480.4.127.25516,382
1980.4.128.0/1880.4.128.1 to 80.4.191.25480.4.191.25516,382
2080.4.192.0/1880.4.192.1 to 80.4.255.25480.4.255.25516,382
2180.5.0.0/1880.5.0.1 to 80.5.63.25480.5.63.25516,382
2280.5.64.0/1880.5.64.1 to 80.5.127.25480.5.127.25516,382
2380.5.128.0/1880.5.128.1 to 80.5.191.25480.5.191.25516,382
2480.5.192.0/1880.5.192.1 to 80.5.255.25480.5.255.25516,382
2580.6.0.0/1880.6.0.1 to 80.6.63.25480.6.63.25516,382
2680.6.64.0/1880.6.64.1 to 80.6.127.25480.6.127.25516,382
2780.6.128.0/1880.6.128.1 to 80.6.191.25480.6.191.25516,382
2880.6.192.0/1880.6.192.1 to 80.6.255.25480.6.255.25516,382
2980.7.0.0/1880.7.0.1 to 80.7.63.25480.7.63.25516,382
3080.7.64.0/1880.7.64.1 to 80.7.127.25480.7.127.25516,382
3180.7.128.0/1880.7.128.1 to 80.7.191.25480.7.191.25516,382
3280.7.192.0/1880.7.192.1 to 80.7.255.25480.7.255.25516,382
3380.8.0.0/1880.8.0.1 to 80.8.63.25480.8.63.25516,382
3480.8.64.0/1880.8.64.1 to 80.8.127.25480.8.127.25516,382
3580.8.128.0/1880.8.128.1 to 80.8.191.25480.8.191.25516,382
3680.8.192.0/1880.8.192.1 to 80.8.255.25480.8.255.25516,382
3780.9.0.0/1880.9.0.1 to 80.9.63.25480.9.63.25516,382
3880.9.64.0/1880.9.64.1 to 80.9.127.25480.9.127.25516,382
3980.9.128.0/1880.9.128.1 to 80.9.191.25480.9.191.25516,382
4080.9.192.0/1880.9.192.1 to 80.9.255.25480.9.255.25516,382
4180.10.0.0/1880.10.0.1 to 80.10.63.25480.10.63.25516,382
4280.10.64.0/1880.10.64.1 to 80.10.127.25480.10.127.25516,382
4380.10.128.0/1880.10.128.1 to 80.10.191.25480.10.191.25516,382
4480.10.192.0/1880.10.192.1 to 80.10.255.25480.10.255.25516,382
4580.11.0.0/1880.11.0.1 to 80.11.63.25480.11.63.25516,382
4680.11.64.0/1880.11.64.1 to 80.11.127.25480.11.127.25516,382
4780.11.128.0/1880.11.128.1 to 80.11.191.25480.11.191.25516,382
4880.11.192.0/1880.11.192.1 to 80.11.255.25480.11.255.25516,382
4980.12.0.0/1880.12.0.1 to 80.12.63.25480.12.63.25516,382
5080.12.64.0/1880.12.64.1 to 80.12.127.25480.12.127.25516,382
5180.12.128.0/1880.12.128.1 to 80.12.191.25480.12.191.25516,382
5280.12.192.0/1880.12.192.1 to 80.12.255.25480.12.255.25516,382
5380.13.0.0/1880.13.0.1 to 80.13.63.25480.13.63.25516,382
5480.13.64.0/1880.13.64.1 to 80.13.127.25480.13.127.25516,382
5580.13.128.0/1880.13.128.1 to 80.13.191.25480.13.191.25516,382
5680.13.192.0/1880.13.192.1 to 80.13.255.25480.13.255.25516,382
5780.14.0.0/1880.14.0.1 to 80.14.63.25480.14.63.25516,382
5880.14.64.0/1880.14.64.1 to 80.14.127.25480.14.127.25516,382
5980.14.128.0/1880.14.128.1 to 80.14.191.25480.14.191.25516,382
6080.14.192.0/1880.14.192.1 to 80.14.255.25480.14.255.25516,382
6180.15.0.0/1880.15.0.1 to 80.15.63.25480.15.63.25516,382
6280.15.64.0/1880.15.64.1 to 80.15.127.25480.15.127.25516,382
6380.15.128.0/1880.15.128.1 to 80.15.191.25480.15.191.25516,382
6480.15.192.0/1880.15.192.1 to 80.15.255.25480.15.255.25516,382
6580.16.0.0/1880.16.0.1 to 80.16.63.25480.16.63.25516,382
6680.16.64.0/1880.16.64.1 to 80.16.127.25480.16.127.25516,382
6780.16.128.0/1880.16.128.1 to 80.16.191.25480.16.191.25516,382
6880.16.192.0/1880.16.192.1 to 80.16.255.25480.16.255.25516,382
6980.17.0.0/1880.17.0.1 to 80.17.63.25480.17.63.25516,382
7080.17.64.0/1880.17.64.1 to 80.17.127.25480.17.127.25516,382
7180.17.128.0/1880.17.128.1 to 80.17.191.25480.17.191.25516,382
7280.17.192.0/1880.17.192.1 to 80.17.255.25480.17.255.25516,382
7380.18.0.0/1880.18.0.1 to 80.18.63.25480.18.63.25516,382
7480.18.64.0/1880.18.64.1 to 80.18.127.25480.18.127.25516,382
7580.18.128.0/1880.18.128.1 to 80.18.191.25480.18.191.25516,382
7680.18.192.0/1880.18.192.1 to 80.18.255.25480.18.255.25516,382
7780.19.0.0/1880.19.0.1 to 80.19.63.25480.19.63.25516,382
7880.19.64.0/1880.19.64.1 to 80.19.127.25480.19.127.25516,382
7980.19.128.0/1880.19.128.1 to 80.19.191.25480.19.191.25516,382
8080.19.192.0/1880.19.192.1 to 80.19.255.25480.19.255.25516,382
8180.20.0.0/1880.20.0.1 to 80.20.63.25480.20.63.25516,382
8280.20.64.0/1880.20.64.1 to 80.20.127.25480.20.127.25516,382
8380.20.128.0/1880.20.128.1 to 80.20.191.25480.20.191.25516,382
8480.20.192.0/1880.20.192.1 to 80.20.255.25480.20.255.25516,382
8580.21.0.0/1880.21.0.1 to 80.21.63.25480.21.63.25516,382
8680.21.64.0/1880.21.64.1 to 80.21.127.25480.21.127.25516,382
8780.21.128.0/1880.21.128.1 to 80.21.191.25480.21.191.25516,382
8880.21.192.0/1880.21.192.1 to 80.21.255.25480.21.255.25516,382
8980.22.0.0/1880.22.0.1 to 80.22.63.25480.22.63.25516,382
9080.22.64.0/1880.22.64.1 to 80.22.127.25480.22.127.25516,382
9180.22.128.0/1880.22.128.1 to 80.22.191.25480.22.191.25516,382
9280.22.192.0/1880.22.192.1 to 80.22.255.25480.22.255.25516,382
9380.23.0.0/1880.23.0.1 to 80.23.63.25480.23.63.25516,382
9480.23.64.0/1880.23.64.1 to 80.23.127.25480.23.127.25516,382
9580.23.128.0/1880.23.128.1 to 80.23.191.25480.23.191.25516,382
9680.23.192.0/1880.23.192.1 to 80.23.255.25480.23.255.25516,382
9780.24.0.0/1880.24.0.1 to 80.24.63.25480.24.63.25516,382
9880.24.64.0/1880.24.64.1 to 80.24.127.25480.24.127.25516,382
9980.24.128.0/1880.24.128.1 to 80.24.191.25480.24.191.25516,382
10080.24.192.0/1880.24.192.1 to 80.24.255.25480.24.255.25516,382
10180.25.0.0/1880.25.0.1 to 80.25.63.25480.25.63.25516,382
10280.25.64.0/1880.25.64.1 to 80.25.127.25480.25.127.25516,382
10380.25.128.0/1880.25.128.1 to 80.25.191.25480.25.191.25516,382
10480.25.192.0/1880.25.192.1 to 80.25.255.25480.25.255.25516,382
10580.26.0.0/1880.26.0.1 to 80.26.63.25480.26.63.25516,382
10680.26.64.0/1880.26.64.1 to 80.26.127.25480.26.127.25516,382
10780.26.128.0/1880.26.128.1 to 80.26.191.25480.26.191.25516,382
10880.26.192.0/1880.26.192.1 to 80.26.255.25480.26.255.25516,382
10980.27.0.0/1880.27.0.1 to 80.27.63.25480.27.63.25516,382
11080.27.64.0/1880.27.64.1 to 80.27.127.25480.27.127.25516,382
11180.27.128.0/1880.27.128.1 to 80.27.191.25480.27.191.25516,382
11280.27.192.0/1880.27.192.1 to 80.27.255.25480.27.255.25516,382
11380.28.0.0/1880.28.0.1 to 80.28.63.25480.28.63.25516,382
11480.28.64.0/1880.28.64.1 to 80.28.127.25480.28.127.25516,382
11580.28.128.0/1880.28.128.1 to 80.28.191.25480.28.191.25516,382
11680.28.192.0/1880.28.192.1 to 80.28.255.25480.28.255.25516,382
11780.29.0.0/1880.29.0.1 to 80.29.63.25480.29.63.25516,382
11880.29.64.0/1880.29.64.1 to 80.29.127.25480.29.127.25516,382
11980.29.128.0/1880.29.128.1 to 80.29.191.25480.29.191.25516,382
12080.29.192.0/1880.29.192.1 to 80.29.255.25480.29.255.25516,382
12180.30.0.0/1880.30.0.1 to 80.30.63.25480.30.63.25516,382
12280.30.64.0/1880.30.64.1 to 80.30.127.25480.30.127.25516,382
12380.30.128.0/1880.30.128.1 to 80.30.191.25480.30.191.25516,382
12480.30.192.0/1880.30.192.1 to 80.30.255.25480.30.255.25516,382
12580.31.0.0/1880.31.0.1 to 80.31.63.25480.31.63.25516,382
12680.31.64.0/1880.31.64.1 to 80.31.127.25480.31.127.25516,382
12780.31.128.0/1880.31.128.1 to 80.31.191.25480.31.191.25516,382
12880.31.192.0/1880.31.192.1 to 80.31.255.25480.31.255.25516,382
12980.32.0.0/1880.32.0.1 to 80.32.63.25480.32.63.25516,382
13080.32.64.0/1880.32.64.1 to 80.32.127.25480.32.127.25516,382
13180.32.128.0/1880.32.128.1 to 80.32.191.25480.32.191.25516,382
13280.32.192.0/1880.32.192.1 to 80.32.255.25480.32.255.25516,382
13380.33.0.0/1880.33.0.1 to 80.33.63.25480.33.63.25516,382
13480.33.64.0/1880.33.64.1 to 80.33.127.25480.33.127.25516,382
13580.33.128.0/1880.33.128.1 to 80.33.191.25480.33.191.25516,382
13680.33.192.0/1880.33.192.1 to 80.33.255.25480.33.255.25516,382
13780.34.0.0/1880.34.0.1 to 80.34.63.25480.34.63.25516,382
13880.34.64.0/1880.34.64.1 to 80.34.127.25480.34.127.25516,382
13980.34.128.0/1880.34.128.1 to 80.34.191.25480.34.191.25516,382
14080.34.192.0/1880.34.192.1 to 80.34.255.25480.34.255.25516,382
14180.35.0.0/1880.35.0.1 to 80.35.63.25480.35.63.25516,382
14280.35.64.0/1880.35.64.1 to 80.35.127.25480.35.127.25516,382
14380.35.128.0/1880.35.128.1 to 80.35.191.25480.35.191.25516,382
14480.35.192.0/1880.35.192.1 to 80.35.255.25480.35.255.25516,382
14580.36.0.0/1880.36.0.1 to 80.36.63.25480.36.63.25516,382
14680.36.64.0/1880.36.64.1 to 80.36.127.25480.36.127.25516,382
14780.36.128.0/1880.36.128.1 to 80.36.191.25480.36.191.25516,382
14880.36.192.0/1880.36.192.1 to 80.36.255.25480.36.255.25516,382
14980.37.0.0/1880.37.0.1 to 80.37.63.25480.37.63.25516,382
15080.37.64.0/1880.37.64.1 to 80.37.127.25480.37.127.25516,382
15180.37.128.0/1880.37.128.1 to 80.37.191.25480.37.191.25516,382
15280.37.192.0/1880.37.192.1 to 80.37.255.25480.37.255.25516,382
15380.38.0.0/1880.38.0.1 to 80.38.63.25480.38.63.25516,382
15480.38.64.0/1880.38.64.1 to 80.38.127.25480.38.127.25516,382
15580.38.128.0/1880.38.128.1 to 80.38.191.25480.38.191.25516,382
15680.38.192.0/1880.38.192.1 to 80.38.255.25480.38.255.25516,382
15780.39.0.0/1880.39.0.1 to 80.39.63.25480.39.63.25516,382
15880.39.64.0/1880.39.64.1 to 80.39.127.25480.39.127.25516,382
15980.39.128.0/1880.39.128.1 to 80.39.191.25480.39.191.25516,382
16080.39.192.0/1880.39.192.1 to 80.39.255.25480.39.255.25516,382
16180.40.0.0/1880.40.0.1 to 80.40.63.25480.40.63.25516,382
16280.40.64.0/1880.40.64.1 to 80.40.127.25480.40.127.25516,382
16380.40.128.0/1880.40.128.1 to 80.40.191.25480.40.191.25516,382
16480.40.192.0/1880.40.192.1 to 80.40.255.25480.40.255.25516,382
16580.41.0.0/1880.41.0.1 to 80.41.63.25480.41.63.25516,382
16680.41.64.0/1880.41.64.1 to 80.41.127.25480.41.127.25516,382
16780.41.128.0/1880.41.128.1 to 80.41.191.25480.41.191.25516,382
16880.41.192.0/1880.41.192.1 to 80.41.255.25480.41.255.25516,382
16980.42.0.0/1880.42.0.1 to 80.42.63.25480.42.63.25516,382
17080.42.64.0/1880.42.64.1 to 80.42.127.25480.42.127.25516,382
17180.42.128.0/1880.42.128.1 to 80.42.191.25480.42.191.25516,382
17280.42.192.0/1880.42.192.1 to 80.42.255.25480.42.255.25516,382
17380.43.0.0/1880.43.0.1 to 80.43.63.25480.43.63.25516,382
17480.43.64.0/1880.43.64.1 to 80.43.127.25480.43.127.25516,382
17580.43.128.0/1880.43.128.1 to 80.43.191.25480.43.191.25516,382
17680.43.192.0/1880.43.192.1 to 80.43.255.25480.43.255.25516,382
17780.44.0.0/1880.44.0.1 to 80.44.63.25480.44.63.25516,382
17880.44.64.0/1880.44.64.1 to 80.44.127.25480.44.127.25516,382
17980.44.128.0/1880.44.128.1 to 80.44.191.25480.44.191.25516,382
18080.44.192.0/1880.44.192.1 to 80.44.255.25480.44.255.25516,382
18180.45.0.0/1880.45.0.1 to 80.45.63.25480.45.63.25516,382
18280.45.64.0/1880.45.64.1 to 80.45.127.25480.45.127.25516,382
18380.45.128.0/1880.45.128.1 to 80.45.191.25480.45.191.25516,382
18480.45.192.0/1880.45.192.1 to 80.45.255.25480.45.255.25516,382
18580.46.0.0/1880.46.0.1 to 80.46.63.25480.46.63.25516,382
18680.46.64.0/1880.46.64.1 to 80.46.127.25480.46.127.25516,382
18780.46.128.0/1880.46.128.1 to 80.46.191.25480.46.191.25516,382
18880.46.192.0/1880.46.192.1 to 80.46.255.25480.46.255.25516,382
18980.47.0.0/1880.47.0.1 to 80.47.63.25480.47.63.25516,382
19080.47.64.0/1880.47.64.1 to 80.47.127.25480.47.127.25516,382
19180.47.128.0/1880.47.128.1 to 80.47.191.25480.47.191.25516,382
19280.47.192.0/1880.47.192.1 to 80.47.255.25480.47.255.25516,382
19380.48.0.0/1880.48.0.1 to 80.48.63.25480.48.63.25516,382
19480.48.64.0/1880.48.64.1 to 80.48.127.25480.48.127.25516,382
19580.48.128.0/1880.48.128.1 to 80.48.191.25480.48.191.25516,382
19680.48.192.0/1880.48.192.1 to 80.48.255.25480.48.255.25516,382
19780.49.0.0/1880.49.0.1 to 80.49.63.25480.49.63.25516,382
19880.49.64.0/1880.49.64.1 to 80.49.127.25480.49.127.25516,382
19980.49.128.0/1880.49.128.1 to 80.49.191.25480.49.191.25516,382
20080.49.192.0/1880.49.192.1 to 80.49.255.25480.49.255.25516,382
20180.50.0.0/1880.50.0.1 to 80.50.63.25480.50.63.25516,382
20280.50.64.0/1880.50.64.1 to 80.50.127.25480.50.127.25516,382
20380.50.128.0/1880.50.128.1 to 80.50.191.25480.50.191.25516,382
20480.50.192.0/1880.50.192.1 to 80.50.255.25480.50.255.25516,382
20580.51.0.0/1880.51.0.1 to 80.51.63.25480.51.63.25516,382
20680.51.64.0/1880.51.64.1 to 80.51.127.25480.51.127.25516,382
20780.51.128.0/1880.51.128.1 to 80.51.191.25480.51.191.25516,382
20880.51.192.0/1880.51.192.1 to 80.51.255.25480.51.255.25516,382
20980.52.0.0/1880.52.0.1 to 80.52.63.25480.52.63.25516,382
21080.52.64.0/1880.52.64.1 to 80.52.127.25480.52.127.25516,382
21180.52.128.0/1880.52.128.1 to 80.52.191.25480.52.191.25516,382
21280.52.192.0/1880.52.192.1 to 80.52.255.25480.52.255.25516,382
21380.53.0.0/1880.53.0.1 to 80.53.63.25480.53.63.25516,382
21480.53.64.0/1880.53.64.1 to 80.53.127.25480.53.127.25516,382
21580.53.128.0/1880.53.128.1 to 80.53.191.25480.53.191.25516,382
21680.53.192.0/1880.53.192.1 to 80.53.255.25480.53.255.25516,382
21780.54.0.0/1880.54.0.1 to 80.54.63.25480.54.63.25516,382
21880.54.64.0/1880.54.64.1 to 80.54.127.25480.54.127.25516,382
21980.54.128.0/1880.54.128.1 to 80.54.191.25480.54.191.25516,382
22080.54.192.0/1880.54.192.1 to 80.54.255.25480.54.255.25516,382
22180.55.0.0/1880.55.0.1 to 80.55.63.25480.55.63.25516,382
22280.55.64.0/1880.55.64.1 to 80.55.127.25480.55.127.25516,382
22380.55.128.0/1880.55.128.1 to 80.55.191.25480.55.191.25516,382
22480.55.192.0/1880.55.192.1 to 80.55.255.25480.55.255.25516,382
22580.56.0.0/1880.56.0.1 to 80.56.63.25480.56.63.25516,382
22680.56.64.0/1880.56.64.1 to 80.56.127.25480.56.127.25516,382
22780.56.128.0/1880.56.128.1 to 80.56.191.25480.56.191.25516,382
22880.56.192.0/1880.56.192.1 to 80.56.255.25480.56.255.25516,382
22980.57.0.0/1880.57.0.1 to 80.57.63.25480.57.63.25516,382
23080.57.64.0/1880.57.64.1 to 80.57.127.25480.57.127.25516,382
23180.57.128.0/1880.57.128.1 to 80.57.191.25480.57.191.25516,382
23280.57.192.0/1880.57.192.1 to 80.57.255.25480.57.255.25516,382
23380.58.0.0/1880.58.0.1 to 80.58.63.25480.58.63.25516,382
23480.58.64.0/1880.58.64.1 to 80.58.127.25480.58.127.25516,382
23580.58.128.0/1880.58.128.1 to 80.58.191.25480.58.191.25516,382
23680.58.192.0/1880.58.192.1 to 80.58.255.25480.58.255.25516,382
23780.59.0.0/1880.59.0.1 to 80.59.63.25480.59.63.25516,382
23880.59.64.0/1880.59.64.1 to 80.59.127.25480.59.127.25516,382
23980.59.128.0/1880.59.128.1 to 80.59.191.25480.59.191.25516,382
24080.59.192.0/1880.59.192.1 to 80.59.255.25480.59.255.25516,382
24180.60.0.0/1880.60.0.1 to 80.60.63.25480.60.63.25516,382
24280.60.64.0/1880.60.64.1 to 80.60.127.25480.60.127.25516,382
24380.60.128.0/1880.60.128.1 to 80.60.191.25480.60.191.25516,382
24480.60.192.0/1880.60.192.1 to 80.60.255.25480.60.255.25516,382
24580.61.0.0/1880.61.0.1 to 80.61.63.25480.61.63.25516,382
24680.61.64.0/1880.61.64.1 to 80.61.127.25480.61.127.25516,382
24780.61.128.0/1880.61.128.1 to 80.61.191.25480.61.191.25516,382
24880.61.192.0/1880.61.192.1 to 80.61.255.25480.61.255.25516,382
24980.62.0.0/1880.62.0.1 to 80.62.63.25480.62.63.25516,382
25080.62.64.0/1880.62.64.1 to 80.62.127.25480.62.127.25516,382
25180.62.128.0/1880.62.128.1 to 80.62.191.25480.62.191.25516,382
25280.62.192.0/1880.62.192.1 to 80.62.255.25480.62.255.25516,382
25380.63.0.0/1880.63.0.1 to 80.63.63.25480.63.63.25516,382
25480.63.64.0/1880.63.64.1 to 80.63.127.25480.63.127.25516,382
25580.63.128.0/1880.63.128.1 to 80.63.191.25480.63.191.25516,382
25680.63.192.0/1880.63.192.1 to 80.63.255.25480.63.255.25516,382

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.