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.

Prefix/16
Addresses2^112
/64 networks2^48
Network
20ed::/16
First address
20ed::
Last address
20ed:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
20ed:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
d.e.0.2.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

20ed::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
120ed::/2420ed:ff:ffff:ffff:ffff:ffff:ffff:ffff
220ed:100::/2420ed:1ff:ffff:ffff:ffff:ffff:ffff:ffff
320ed:200::/2420ed:2ff:ffff:ffff:ffff:ffff:ffff:ffff
420ed:300::/2420ed:3ff:ffff:ffff:ffff:ffff:ffff:ffff
520ed:400::/2420ed:4ff:ffff:ffff:ffff:ffff:ffff:ffff
620ed:500::/2420ed:5ff:ffff:ffff:ffff:ffff:ffff:ffff
720ed:600::/2420ed:6ff:ffff:ffff:ffff:ffff:ffff:ffff
820ed:700::/2420ed:7ff:ffff:ffff:ffff:ffff:ffff:ffff
920ed:800::/2420ed:8ff:ffff:ffff:ffff:ffff:ffff:ffff
1020ed:900::/2420ed:9ff:ffff:ffff:ffff:ffff:ffff:ffff
1120ed:a00::/2420ed:aff:ffff:ffff:ffff:ffff:ffff:ffff
1220ed:b00::/2420ed:bff:ffff:ffff:ffff:ffff:ffff:ffff
1320ed:c00::/2420ed:cff:ffff:ffff:ffff:ffff:ffff:ffff
1420ed:d00::/2420ed:dff:ffff:ffff:ffff:ffff:ffff:ffff
1520ed:e00::/2420ed:eff:ffff:ffff:ffff:ffff:ffff:ffff
1620ed:f00::/2420ed:fff:ffff:ffff:ffff:ffff:ffff:ffff
1720ed:1000::/2420ed:10ff:ffff:ffff:ffff:ffff:ffff:ffff
1820ed:1100::/2420ed:11ff:ffff:ffff:ffff:ffff:ffff:ffff
1920ed:1200::/2420ed:12ff:ffff:ffff:ffff:ffff:ffff:ffff
2020ed:1300::/2420ed:13ff:ffff:ffff:ffff:ffff:ffff:ffff
2120ed:1400::/2420ed:14ff:ffff:ffff:ffff:ffff:ffff:ffff
2220ed:1500::/2420ed:15ff:ffff:ffff:ffff:ffff:ffff:ffff
2320ed:1600::/2420ed:16ff:ffff:ffff:ffff:ffff:ffff:ffff
2420ed:1700::/2420ed:17ff:ffff:ffff:ffff:ffff:ffff:ffff
2520ed:1800::/2420ed:18ff:ffff:ffff:ffff:ffff:ffff:ffff
2620ed:1900::/2420ed:19ff:ffff:ffff:ffff:ffff:ffff:ffff
2720ed:1a00::/2420ed:1aff:ffff:ffff:ffff:ffff:ffff:ffff
2820ed:1b00::/2420ed:1bff:ffff:ffff:ffff:ffff:ffff:ffff
2920ed:1c00::/2420ed:1cff:ffff:ffff:ffff:ffff:ffff:ffff
3020ed:1d00::/2420ed:1dff:ffff:ffff:ffff:ffff:ffff:ffff
3120ed:1e00::/2420ed:1eff:ffff:ffff:ffff:ffff:ffff:ffff
3220ed:1f00::/2420ed:1fff:ffff:ffff:ffff:ffff:ffff:ffff
3320ed:2000::/2420ed:20ff:ffff:ffff:ffff:ffff:ffff:ffff
3420ed:2100::/2420ed:21ff:ffff:ffff:ffff:ffff:ffff:ffff
3520ed:2200::/2420ed:22ff:ffff:ffff:ffff:ffff:ffff:ffff
3620ed:2300::/2420ed:23ff:ffff:ffff:ffff:ffff:ffff:ffff
3720ed:2400::/2420ed:24ff:ffff:ffff:ffff:ffff:ffff:ffff
3820ed:2500::/2420ed:25ff:ffff:ffff:ffff:ffff:ffff:ffff
3920ed:2600::/2420ed:26ff:ffff:ffff:ffff:ffff:ffff:ffff
4020ed:2700::/2420ed:27ff:ffff:ffff:ffff:ffff:ffff:ffff
4120ed:2800::/2420ed:28ff:ffff:ffff:ffff:ffff:ffff:ffff
4220ed:2900::/2420ed:29ff:ffff:ffff:ffff:ffff:ffff:ffff
4320ed:2a00::/2420ed:2aff:ffff:ffff:ffff:ffff:ffff:ffff
4420ed:2b00::/2420ed:2bff:ffff:ffff:ffff:ffff:ffff:ffff
4520ed:2c00::/2420ed:2cff:ffff:ffff:ffff:ffff:ffff:ffff
4620ed:2d00::/2420ed:2dff:ffff:ffff:ffff:ffff:ffff:ffff
4720ed:2e00::/2420ed:2eff:ffff:ffff:ffff:ffff:ffff:ffff
4820ed:2f00::/2420ed:2fff:ffff:ffff:ffff:ffff:ffff:ffff
4920ed:3000::/2420ed:30ff:ffff:ffff:ffff:ffff:ffff:ffff
5020ed:3100::/2420ed:31ff:ffff:ffff:ffff:ffff:ffff:ffff
5120ed:3200::/2420ed:32ff:ffff:ffff:ffff:ffff:ffff:ffff
5220ed:3300::/2420ed:33ff:ffff:ffff:ffff:ffff:ffff:ffff
5320ed:3400::/2420ed:34ff:ffff:ffff:ffff:ffff:ffff:ffff
5420ed:3500::/2420ed:35ff:ffff:ffff:ffff:ffff:ffff:ffff
5520ed:3600::/2420ed:36ff:ffff:ffff:ffff:ffff:ffff:ffff
5620ed:3700::/2420ed:37ff:ffff:ffff:ffff:ffff:ffff:ffff
5720ed:3800::/2420ed:38ff:ffff:ffff:ffff:ffff:ffff:ffff
5820ed:3900::/2420ed:39ff:ffff:ffff:ffff:ffff:ffff:ffff
5920ed:3a00::/2420ed:3aff:ffff:ffff:ffff:ffff:ffff:ffff
6020ed:3b00::/2420ed:3bff:ffff:ffff:ffff:ffff:ffff:ffff
6120ed:3c00::/2420ed:3cff:ffff:ffff:ffff:ffff:ffff:ffff
6220ed:3d00::/2420ed:3dff:ffff:ffff:ffff:ffff:ffff:ffff
6320ed:3e00::/2420ed:3eff:ffff:ffff:ffff:ffff:ffff:ffff
6420ed:3f00::/2420ed:3fff:ffff:ffff:ffff:ffff:ffff:ffff
6520ed:4000::/2420ed:40ff:ffff:ffff:ffff:ffff:ffff:ffff
6620ed:4100::/2420ed:41ff:ffff:ffff:ffff:ffff:ffff:ffff
6720ed:4200::/2420ed:42ff:ffff:ffff:ffff:ffff:ffff:ffff
6820ed:4300::/2420ed:43ff:ffff:ffff:ffff:ffff:ffff:ffff
6920ed:4400::/2420ed:44ff:ffff:ffff:ffff:ffff:ffff:ffff
7020ed:4500::/2420ed:45ff:ffff:ffff:ffff:ffff:ffff:ffff
7120ed:4600::/2420ed:46ff:ffff:ffff:ffff:ffff:ffff:ffff
7220ed:4700::/2420ed:47ff:ffff:ffff:ffff:ffff:ffff:ffff
7320ed:4800::/2420ed:48ff:ffff:ffff:ffff:ffff:ffff:ffff
7420ed:4900::/2420ed:49ff:ffff:ffff:ffff:ffff:ffff:ffff
7520ed:4a00::/2420ed:4aff:ffff:ffff:ffff:ffff:ffff:ffff
7620ed:4b00::/2420ed:4bff:ffff:ffff:ffff:ffff:ffff:ffff
7720ed:4c00::/2420ed:4cff:ffff:ffff:ffff:ffff:ffff:ffff
7820ed:4d00::/2420ed:4dff:ffff:ffff:ffff:ffff:ffff:ffff
7920ed:4e00::/2420ed:4eff:ffff:ffff:ffff:ffff:ffff:ffff
8020ed:4f00::/2420ed:4fff:ffff:ffff:ffff:ffff:ffff:ffff
8120ed:5000::/2420ed:50ff:ffff:ffff:ffff:ffff:ffff:ffff
8220ed:5100::/2420ed:51ff:ffff:ffff:ffff:ffff:ffff:ffff
8320ed:5200::/2420ed:52ff:ffff:ffff:ffff:ffff:ffff:ffff
8420ed:5300::/2420ed:53ff:ffff:ffff:ffff:ffff:ffff:ffff
8520ed:5400::/2420ed:54ff:ffff:ffff:ffff:ffff:ffff:ffff
8620ed:5500::/2420ed:55ff:ffff:ffff:ffff:ffff:ffff:ffff
8720ed:5600::/2420ed:56ff:ffff:ffff:ffff:ffff:ffff:ffff
8820ed:5700::/2420ed:57ff:ffff:ffff:ffff:ffff:ffff:ffff
8920ed:5800::/2420ed:58ff:ffff:ffff:ffff:ffff:ffff:ffff
9020ed:5900::/2420ed:59ff:ffff:ffff:ffff:ffff:ffff:ffff
9120ed:5a00::/2420ed:5aff:ffff:ffff:ffff:ffff:ffff:ffff
9220ed:5b00::/2420ed:5bff:ffff:ffff:ffff:ffff:ffff:ffff
9320ed:5c00::/2420ed:5cff:ffff:ffff:ffff:ffff:ffff:ffff
9420ed:5d00::/2420ed:5dff:ffff:ffff:ffff:ffff:ffff:ffff
9520ed:5e00::/2420ed:5eff:ffff:ffff:ffff:ffff:ffff:ffff
9620ed:5f00::/2420ed:5fff:ffff:ffff:ffff:ffff:ffff:ffff
9720ed:6000::/2420ed:60ff:ffff:ffff:ffff:ffff:ffff:ffff
9820ed:6100::/2420ed:61ff:ffff:ffff:ffff:ffff:ffff:ffff
9920ed:6200::/2420ed:62ff:ffff:ffff:ffff:ffff:ffff:ffff
10020ed:6300::/2420ed:63ff:ffff:ffff:ffff:ffff:ffff:ffff
10120ed:6400::/2420ed:64ff:ffff:ffff:ffff:ffff:ffff:ffff
10220ed:6500::/2420ed:65ff:ffff:ffff:ffff:ffff:ffff:ffff
10320ed:6600::/2420ed:66ff:ffff:ffff:ffff:ffff:ffff:ffff
10420ed:6700::/2420ed:67ff:ffff:ffff:ffff:ffff:ffff:ffff
10520ed:6800::/2420ed:68ff:ffff:ffff:ffff:ffff:ffff:ffff
10620ed:6900::/2420ed:69ff:ffff:ffff:ffff:ffff:ffff:ffff
10720ed:6a00::/2420ed:6aff:ffff:ffff:ffff:ffff:ffff:ffff
10820ed:6b00::/2420ed:6bff:ffff:ffff:ffff:ffff:ffff:ffff
10920ed:6c00::/2420ed:6cff:ffff:ffff:ffff:ffff:ffff:ffff
11020ed:6d00::/2420ed:6dff:ffff:ffff:ffff:ffff:ffff:ffff
11120ed:6e00::/2420ed:6eff:ffff:ffff:ffff:ffff:ffff:ffff
11220ed:6f00::/2420ed:6fff:ffff:ffff:ffff:ffff:ffff:ffff
11320ed:7000::/2420ed:70ff:ffff:ffff:ffff:ffff:ffff:ffff
11420ed:7100::/2420ed:71ff:ffff:ffff:ffff:ffff:ffff:ffff
11520ed:7200::/2420ed:72ff:ffff:ffff:ffff:ffff:ffff:ffff
11620ed:7300::/2420ed:73ff:ffff:ffff:ffff:ffff:ffff:ffff
11720ed:7400::/2420ed:74ff:ffff:ffff:ffff:ffff:ffff:ffff
11820ed:7500::/2420ed:75ff:ffff:ffff:ffff:ffff:ffff:ffff
11920ed:7600::/2420ed:76ff:ffff:ffff:ffff:ffff:ffff:ffff
12020ed:7700::/2420ed:77ff:ffff:ffff:ffff:ffff:ffff:ffff
12120ed:7800::/2420ed:78ff:ffff:ffff:ffff:ffff:ffff:ffff
12220ed:7900::/2420ed:79ff:ffff:ffff:ffff:ffff:ffff:ffff
12320ed:7a00::/2420ed:7aff:ffff:ffff:ffff:ffff:ffff:ffff
12420ed:7b00::/2420ed:7bff:ffff:ffff:ffff:ffff:ffff:ffff
12520ed:7c00::/2420ed:7cff:ffff:ffff:ffff:ffff:ffff:ffff
12620ed:7d00::/2420ed:7dff:ffff:ffff:ffff:ffff:ffff:ffff
12720ed:7e00::/2420ed:7eff:ffff:ffff:ffff:ffff:ffff:ffff
12820ed:7f00::/2420ed:7fff:ffff:ffff:ffff:ffff:ffff:ffff
12920ed:8000::/2420ed:80ff:ffff:ffff:ffff:ffff:ffff:ffff
13020ed:8100::/2420ed:81ff:ffff:ffff:ffff:ffff:ffff:ffff
13120ed:8200::/2420ed:82ff:ffff:ffff:ffff:ffff:ffff:ffff
13220ed:8300::/2420ed:83ff:ffff:ffff:ffff:ffff:ffff:ffff
13320ed:8400::/2420ed:84ff:ffff:ffff:ffff:ffff:ffff:ffff
13420ed:8500::/2420ed:85ff:ffff:ffff:ffff:ffff:ffff:ffff
13520ed:8600::/2420ed:86ff:ffff:ffff:ffff:ffff:ffff:ffff
13620ed:8700::/2420ed:87ff:ffff:ffff:ffff:ffff:ffff:ffff
13720ed:8800::/2420ed:88ff:ffff:ffff:ffff:ffff:ffff:ffff
13820ed:8900::/2420ed:89ff:ffff:ffff:ffff:ffff:ffff:ffff
13920ed:8a00::/2420ed:8aff:ffff:ffff:ffff:ffff:ffff:ffff
14020ed:8b00::/2420ed:8bff:ffff:ffff:ffff:ffff:ffff:ffff
14120ed:8c00::/2420ed:8cff:ffff:ffff:ffff:ffff:ffff:ffff
14220ed:8d00::/2420ed:8dff:ffff:ffff:ffff:ffff:ffff:ffff
14320ed:8e00::/2420ed:8eff:ffff:ffff:ffff:ffff:ffff:ffff
14420ed:8f00::/2420ed:8fff:ffff:ffff:ffff:ffff:ffff:ffff
14520ed:9000::/2420ed:90ff:ffff:ffff:ffff:ffff:ffff:ffff
14620ed:9100::/2420ed:91ff:ffff:ffff:ffff:ffff:ffff:ffff
14720ed:9200::/2420ed:92ff:ffff:ffff:ffff:ffff:ffff:ffff
14820ed:9300::/2420ed:93ff:ffff:ffff:ffff:ffff:ffff:ffff
14920ed:9400::/2420ed:94ff:ffff:ffff:ffff:ffff:ffff:ffff
15020ed:9500::/2420ed:95ff:ffff:ffff:ffff:ffff:ffff:ffff
15120ed:9600::/2420ed:96ff:ffff:ffff:ffff:ffff:ffff:ffff
15220ed:9700::/2420ed:97ff:ffff:ffff:ffff:ffff:ffff:ffff
15320ed:9800::/2420ed:98ff:ffff:ffff:ffff:ffff:ffff:ffff
15420ed:9900::/2420ed:99ff:ffff:ffff:ffff:ffff:ffff:ffff
15520ed:9a00::/2420ed:9aff:ffff:ffff:ffff:ffff:ffff:ffff
15620ed:9b00::/2420ed:9bff:ffff:ffff:ffff:ffff:ffff:ffff
15720ed:9c00::/2420ed:9cff:ffff:ffff:ffff:ffff:ffff:ffff
15820ed:9d00::/2420ed:9dff:ffff:ffff:ffff:ffff:ffff:ffff
15920ed:9e00::/2420ed:9eff:ffff:ffff:ffff:ffff:ffff:ffff
16020ed:9f00::/2420ed:9fff:ffff:ffff:ffff:ffff:ffff:ffff
16120ed:a000::/2420ed:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
16220ed:a100::/2420ed:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
16320ed:a200::/2420ed:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
16420ed:a300::/2420ed:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
16520ed:a400::/2420ed:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
16620ed:a500::/2420ed:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
16720ed:a600::/2420ed:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
16820ed:a700::/2420ed:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
16920ed:a800::/2420ed:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
17020ed:a900::/2420ed:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
17120ed:aa00::/2420ed:aaff:ffff:ffff:ffff:ffff:ffff:ffff
17220ed:ab00::/2420ed:abff:ffff:ffff:ffff:ffff:ffff:ffff
17320ed:ac00::/2420ed:acff:ffff:ffff:ffff:ffff:ffff:ffff
17420ed:ad00::/2420ed:adff:ffff:ffff:ffff:ffff:ffff:ffff
17520ed:ae00::/2420ed:aeff:ffff:ffff:ffff:ffff:ffff:ffff
17620ed:af00::/2420ed:afff:ffff:ffff:ffff:ffff:ffff:ffff
17720ed:b000::/2420ed:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
17820ed:b100::/2420ed:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
17920ed:b200::/2420ed:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
18020ed:b300::/2420ed:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
18120ed:b400::/2420ed:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
18220ed:b500::/2420ed:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
18320ed:b600::/2420ed:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
18420ed:b700::/2420ed:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
18520ed:b800::/2420ed:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
18620ed:b900::/2420ed:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
18720ed:ba00::/2420ed:baff:ffff:ffff:ffff:ffff:ffff:ffff
18820ed:bb00::/2420ed:bbff:ffff:ffff:ffff:ffff:ffff:ffff
18920ed:bc00::/2420ed:bcff:ffff:ffff:ffff:ffff:ffff:ffff
19020ed:bd00::/2420ed:bdff:ffff:ffff:ffff:ffff:ffff:ffff
19120ed:be00::/2420ed:beff:ffff:ffff:ffff:ffff:ffff:ffff
19220ed:bf00::/2420ed:bfff:ffff:ffff:ffff:ffff:ffff:ffff
19320ed:c000::/2420ed:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
19420ed:c100::/2420ed:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
19520ed:c200::/2420ed:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
19620ed:c300::/2420ed:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
19720ed:c400::/2420ed:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
19820ed:c500::/2420ed:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
19920ed:c600::/2420ed:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
20020ed:c700::/2420ed:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
20120ed:c800::/2420ed:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
20220ed:c900::/2420ed:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
20320ed:ca00::/2420ed:caff:ffff:ffff:ffff:ffff:ffff:ffff
20420ed:cb00::/2420ed:cbff:ffff:ffff:ffff:ffff:ffff:ffff
20520ed:cc00::/2420ed:ccff:ffff:ffff:ffff:ffff:ffff:ffff
20620ed:cd00::/2420ed:cdff:ffff:ffff:ffff:ffff:ffff:ffff
20720ed:ce00::/2420ed:ceff:ffff:ffff:ffff:ffff:ffff:ffff
20820ed:cf00::/2420ed:cfff:ffff:ffff:ffff:ffff:ffff:ffff
20920ed:d000::/2420ed:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
21020ed:d100::/2420ed:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
21120ed:d200::/2420ed:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
21220ed:d300::/2420ed:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
21320ed:d400::/2420ed:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
21420ed:d500::/2420ed:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
21520ed:d600::/2420ed:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
21620ed:d700::/2420ed:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
21720ed:d800::/2420ed:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
21820ed:d900::/2420ed:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
21920ed:da00::/2420ed:daff:ffff:ffff:ffff:ffff:ffff:ffff
22020ed:db00::/2420ed:dbff:ffff:ffff:ffff:ffff:ffff:ffff
22120ed:dc00::/2420ed:dcff:ffff:ffff:ffff:ffff:ffff:ffff
22220ed:dd00::/2420ed:ddff:ffff:ffff:ffff:ffff:ffff:ffff
22320ed:de00::/2420ed:deff:ffff:ffff:ffff:ffff:ffff:ffff
22420ed:df00::/2420ed:dfff:ffff:ffff:ffff:ffff:ffff:ffff
22520ed:e000::/2420ed:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
22620ed:e100::/2420ed:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
22720ed:e200::/2420ed:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
22820ed:e300::/2420ed:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
22920ed:e400::/2420ed:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
23020ed:e500::/2420ed:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
23120ed:e600::/2420ed:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
23220ed:e700::/2420ed:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
23320ed:e800::/2420ed:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
23420ed:e900::/2420ed:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
23520ed:ea00::/2420ed:eaff:ffff:ffff:ffff:ffff:ffff:ffff
23620ed:eb00::/2420ed:ebff:ffff:ffff:ffff:ffff:ffff:ffff
23720ed:ec00::/2420ed:ecff:ffff:ffff:ffff:ffff:ffff:ffff
23820ed:ed00::/2420ed:edff:ffff:ffff:ffff:ffff:ffff:ffff
23920ed:ee00::/2420ed:eeff:ffff:ffff:ffff:ffff:ffff:ffff
24020ed:ef00::/2420ed:efff:ffff:ffff:ffff:ffff:ffff:ffff
24120ed:f000::/2420ed:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
24220ed:f100::/2420ed:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
24320ed:f200::/2420ed:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
24420ed:f300::/2420ed:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
24520ed:f400::/2420ed:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
24620ed:f500::/2420ed:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
24720ed:f600::/2420ed:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
24820ed:f700::/2420ed:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
24920ed:f800::/2420ed:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
25020ed:f900::/2420ed:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
25120ed:fa00::/2420ed:faff:ffff:ffff:ffff:ffff:ffff:ffff
25220ed:fb00::/2420ed:fbff:ffff:ffff:ffff:ffff:ffff:ffff
25320ed:fc00::/2420ed:fcff:ffff:ffff:ffff:ffff:ffff:ffff
25420ed:fd00::/2420ed:fdff:ffff:ffff:ffff:ffff:ffff:ffff
25520ed:fe00::/2420ed:feff:ffff:ffff:ffff:ffff:ffff:ffff
25620ed:ff00::/2420ed:ffff:ffff:ffff:ffff:ffff:ffff:ffff

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.