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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.

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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.

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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.

Prefix/16
Addresses2^112
/64 networks2^48
Network
20b0::/16
First address
20b0::
Last address
20b0: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
20b0:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
0.b.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)

20b0::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
120b0::/2420b0:ff:ffff:ffff:ffff:ffff:ffff:ffff
220b0:100::/2420b0:1ff:ffff:ffff:ffff:ffff:ffff:ffff
320b0:200::/2420b0:2ff:ffff:ffff:ffff:ffff:ffff:ffff
420b0:300::/2420b0:3ff:ffff:ffff:ffff:ffff:ffff:ffff
520b0:400::/2420b0:4ff:ffff:ffff:ffff:ffff:ffff:ffff
620b0:500::/2420b0:5ff:ffff:ffff:ffff:ffff:ffff:ffff
720b0:600::/2420b0:6ff:ffff:ffff:ffff:ffff:ffff:ffff
820b0:700::/2420b0:7ff:ffff:ffff:ffff:ffff:ffff:ffff
920b0:800::/2420b0:8ff:ffff:ffff:ffff:ffff:ffff:ffff
1020b0:900::/2420b0:9ff:ffff:ffff:ffff:ffff:ffff:ffff
1120b0:a00::/2420b0:aff:ffff:ffff:ffff:ffff:ffff:ffff
1220b0:b00::/2420b0:bff:ffff:ffff:ffff:ffff:ffff:ffff
1320b0:c00::/2420b0:cff:ffff:ffff:ffff:ffff:ffff:ffff
1420b0:d00::/2420b0:dff:ffff:ffff:ffff:ffff:ffff:ffff
1520b0:e00::/2420b0:eff:ffff:ffff:ffff:ffff:ffff:ffff
1620b0:f00::/2420b0:fff:ffff:ffff:ffff:ffff:ffff:ffff
1720b0:1000::/2420b0:10ff:ffff:ffff:ffff:ffff:ffff:ffff
1820b0:1100::/2420b0:11ff:ffff:ffff:ffff:ffff:ffff:ffff
1920b0:1200::/2420b0:12ff:ffff:ffff:ffff:ffff:ffff:ffff
2020b0:1300::/2420b0:13ff:ffff:ffff:ffff:ffff:ffff:ffff
2120b0:1400::/2420b0:14ff:ffff:ffff:ffff:ffff:ffff:ffff
2220b0:1500::/2420b0:15ff:ffff:ffff:ffff:ffff:ffff:ffff
2320b0:1600::/2420b0:16ff:ffff:ffff:ffff:ffff:ffff:ffff
2420b0:1700::/2420b0:17ff:ffff:ffff:ffff:ffff:ffff:ffff
2520b0:1800::/2420b0:18ff:ffff:ffff:ffff:ffff:ffff:ffff
2620b0:1900::/2420b0:19ff:ffff:ffff:ffff:ffff:ffff:ffff
2720b0:1a00::/2420b0:1aff:ffff:ffff:ffff:ffff:ffff:ffff
2820b0:1b00::/2420b0:1bff:ffff:ffff:ffff:ffff:ffff:ffff
2920b0:1c00::/2420b0:1cff:ffff:ffff:ffff:ffff:ffff:ffff
3020b0:1d00::/2420b0:1dff:ffff:ffff:ffff:ffff:ffff:ffff
3120b0:1e00::/2420b0:1eff:ffff:ffff:ffff:ffff:ffff:ffff
3220b0:1f00::/2420b0:1fff:ffff:ffff:ffff:ffff:ffff:ffff
3320b0:2000::/2420b0:20ff:ffff:ffff:ffff:ffff:ffff:ffff
3420b0:2100::/2420b0:21ff:ffff:ffff:ffff:ffff:ffff:ffff
3520b0:2200::/2420b0:22ff:ffff:ffff:ffff:ffff:ffff:ffff
3620b0:2300::/2420b0:23ff:ffff:ffff:ffff:ffff:ffff:ffff
3720b0:2400::/2420b0:24ff:ffff:ffff:ffff:ffff:ffff:ffff
3820b0:2500::/2420b0:25ff:ffff:ffff:ffff:ffff:ffff:ffff
3920b0:2600::/2420b0:26ff:ffff:ffff:ffff:ffff:ffff:ffff
4020b0:2700::/2420b0:27ff:ffff:ffff:ffff:ffff:ffff:ffff
4120b0:2800::/2420b0:28ff:ffff:ffff:ffff:ffff:ffff:ffff
4220b0:2900::/2420b0:29ff:ffff:ffff:ffff:ffff:ffff:ffff
4320b0:2a00::/2420b0:2aff:ffff:ffff:ffff:ffff:ffff:ffff
4420b0:2b00::/2420b0:2bff:ffff:ffff:ffff:ffff:ffff:ffff
4520b0:2c00::/2420b0:2cff:ffff:ffff:ffff:ffff:ffff:ffff
4620b0:2d00::/2420b0:2dff:ffff:ffff:ffff:ffff:ffff:ffff
4720b0:2e00::/2420b0:2eff:ffff:ffff:ffff:ffff:ffff:ffff
4820b0:2f00::/2420b0:2fff:ffff:ffff:ffff:ffff:ffff:ffff
4920b0:3000::/2420b0:30ff:ffff:ffff:ffff:ffff:ffff:ffff
5020b0:3100::/2420b0:31ff:ffff:ffff:ffff:ffff:ffff:ffff
5120b0:3200::/2420b0:32ff:ffff:ffff:ffff:ffff:ffff:ffff
5220b0:3300::/2420b0:33ff:ffff:ffff:ffff:ffff:ffff:ffff
5320b0:3400::/2420b0:34ff:ffff:ffff:ffff:ffff:ffff:ffff
5420b0:3500::/2420b0:35ff:ffff:ffff:ffff:ffff:ffff:ffff
5520b0:3600::/2420b0:36ff:ffff:ffff:ffff:ffff:ffff:ffff
5620b0:3700::/2420b0:37ff:ffff:ffff:ffff:ffff:ffff:ffff
5720b0:3800::/2420b0:38ff:ffff:ffff:ffff:ffff:ffff:ffff
5820b0:3900::/2420b0:39ff:ffff:ffff:ffff:ffff:ffff:ffff
5920b0:3a00::/2420b0:3aff:ffff:ffff:ffff:ffff:ffff:ffff
6020b0:3b00::/2420b0:3bff:ffff:ffff:ffff:ffff:ffff:ffff
6120b0:3c00::/2420b0:3cff:ffff:ffff:ffff:ffff:ffff:ffff
6220b0:3d00::/2420b0:3dff:ffff:ffff:ffff:ffff:ffff:ffff
6320b0:3e00::/2420b0:3eff:ffff:ffff:ffff:ffff:ffff:ffff
6420b0:3f00::/2420b0:3fff:ffff:ffff:ffff:ffff:ffff:ffff
6520b0:4000::/2420b0:40ff:ffff:ffff:ffff:ffff:ffff:ffff
6620b0:4100::/2420b0:41ff:ffff:ffff:ffff:ffff:ffff:ffff
6720b0:4200::/2420b0:42ff:ffff:ffff:ffff:ffff:ffff:ffff
6820b0:4300::/2420b0:43ff:ffff:ffff:ffff:ffff:ffff:ffff
6920b0:4400::/2420b0:44ff:ffff:ffff:ffff:ffff:ffff:ffff
7020b0:4500::/2420b0:45ff:ffff:ffff:ffff:ffff:ffff:ffff
7120b0:4600::/2420b0:46ff:ffff:ffff:ffff:ffff:ffff:ffff
7220b0:4700::/2420b0:47ff:ffff:ffff:ffff:ffff:ffff:ffff
7320b0:4800::/2420b0:48ff:ffff:ffff:ffff:ffff:ffff:ffff
7420b0:4900::/2420b0:49ff:ffff:ffff:ffff:ffff:ffff:ffff
7520b0:4a00::/2420b0:4aff:ffff:ffff:ffff:ffff:ffff:ffff
7620b0:4b00::/2420b0:4bff:ffff:ffff:ffff:ffff:ffff:ffff
7720b0:4c00::/2420b0:4cff:ffff:ffff:ffff:ffff:ffff:ffff
7820b0:4d00::/2420b0:4dff:ffff:ffff:ffff:ffff:ffff:ffff
7920b0:4e00::/2420b0:4eff:ffff:ffff:ffff:ffff:ffff:ffff
8020b0:4f00::/2420b0:4fff:ffff:ffff:ffff:ffff:ffff:ffff
8120b0:5000::/2420b0:50ff:ffff:ffff:ffff:ffff:ffff:ffff
8220b0:5100::/2420b0:51ff:ffff:ffff:ffff:ffff:ffff:ffff
8320b0:5200::/2420b0:52ff:ffff:ffff:ffff:ffff:ffff:ffff
8420b0:5300::/2420b0:53ff:ffff:ffff:ffff:ffff:ffff:ffff
8520b0:5400::/2420b0:54ff:ffff:ffff:ffff:ffff:ffff:ffff
8620b0:5500::/2420b0:55ff:ffff:ffff:ffff:ffff:ffff:ffff
8720b0:5600::/2420b0:56ff:ffff:ffff:ffff:ffff:ffff:ffff
8820b0:5700::/2420b0:57ff:ffff:ffff:ffff:ffff:ffff:ffff
8920b0:5800::/2420b0:58ff:ffff:ffff:ffff:ffff:ffff:ffff
9020b0:5900::/2420b0:59ff:ffff:ffff:ffff:ffff:ffff:ffff
9120b0:5a00::/2420b0:5aff:ffff:ffff:ffff:ffff:ffff:ffff
9220b0:5b00::/2420b0:5bff:ffff:ffff:ffff:ffff:ffff:ffff
9320b0:5c00::/2420b0:5cff:ffff:ffff:ffff:ffff:ffff:ffff
9420b0:5d00::/2420b0:5dff:ffff:ffff:ffff:ffff:ffff:ffff
9520b0:5e00::/2420b0:5eff:ffff:ffff:ffff:ffff:ffff:ffff
9620b0:5f00::/2420b0:5fff:ffff:ffff:ffff:ffff:ffff:ffff
9720b0:6000::/2420b0:60ff:ffff:ffff:ffff:ffff:ffff:ffff
9820b0:6100::/2420b0:61ff:ffff:ffff:ffff:ffff:ffff:ffff
9920b0:6200::/2420b0:62ff:ffff:ffff:ffff:ffff:ffff:ffff
10020b0:6300::/2420b0:63ff:ffff:ffff:ffff:ffff:ffff:ffff
10120b0:6400::/2420b0:64ff:ffff:ffff:ffff:ffff:ffff:ffff
10220b0:6500::/2420b0:65ff:ffff:ffff:ffff:ffff:ffff:ffff
10320b0:6600::/2420b0:66ff:ffff:ffff:ffff:ffff:ffff:ffff
10420b0:6700::/2420b0:67ff:ffff:ffff:ffff:ffff:ffff:ffff
10520b0:6800::/2420b0:68ff:ffff:ffff:ffff:ffff:ffff:ffff
10620b0:6900::/2420b0:69ff:ffff:ffff:ffff:ffff:ffff:ffff
10720b0:6a00::/2420b0:6aff:ffff:ffff:ffff:ffff:ffff:ffff
10820b0:6b00::/2420b0:6bff:ffff:ffff:ffff:ffff:ffff:ffff
10920b0:6c00::/2420b0:6cff:ffff:ffff:ffff:ffff:ffff:ffff
11020b0:6d00::/2420b0:6dff:ffff:ffff:ffff:ffff:ffff:ffff
11120b0:6e00::/2420b0:6eff:ffff:ffff:ffff:ffff:ffff:ffff
11220b0:6f00::/2420b0:6fff:ffff:ffff:ffff:ffff:ffff:ffff
11320b0:7000::/2420b0:70ff:ffff:ffff:ffff:ffff:ffff:ffff
11420b0:7100::/2420b0:71ff:ffff:ffff:ffff:ffff:ffff:ffff
11520b0:7200::/2420b0:72ff:ffff:ffff:ffff:ffff:ffff:ffff
11620b0:7300::/2420b0:73ff:ffff:ffff:ffff:ffff:ffff:ffff
11720b0:7400::/2420b0:74ff:ffff:ffff:ffff:ffff:ffff:ffff
11820b0:7500::/2420b0:75ff:ffff:ffff:ffff:ffff:ffff:ffff
11920b0:7600::/2420b0:76ff:ffff:ffff:ffff:ffff:ffff:ffff
12020b0:7700::/2420b0:77ff:ffff:ffff:ffff:ffff:ffff:ffff
12120b0:7800::/2420b0:78ff:ffff:ffff:ffff:ffff:ffff:ffff
12220b0:7900::/2420b0:79ff:ffff:ffff:ffff:ffff:ffff:ffff
12320b0:7a00::/2420b0:7aff:ffff:ffff:ffff:ffff:ffff:ffff
12420b0:7b00::/2420b0:7bff:ffff:ffff:ffff:ffff:ffff:ffff
12520b0:7c00::/2420b0:7cff:ffff:ffff:ffff:ffff:ffff:ffff
12620b0:7d00::/2420b0:7dff:ffff:ffff:ffff:ffff:ffff:ffff
12720b0:7e00::/2420b0:7eff:ffff:ffff:ffff:ffff:ffff:ffff
12820b0:7f00::/2420b0:7fff:ffff:ffff:ffff:ffff:ffff:ffff
12920b0:8000::/2420b0:80ff:ffff:ffff:ffff:ffff:ffff:ffff
13020b0:8100::/2420b0:81ff:ffff:ffff:ffff:ffff:ffff:ffff
13120b0:8200::/2420b0:82ff:ffff:ffff:ffff:ffff:ffff:ffff
13220b0:8300::/2420b0:83ff:ffff:ffff:ffff:ffff:ffff:ffff
13320b0:8400::/2420b0:84ff:ffff:ffff:ffff:ffff:ffff:ffff
13420b0:8500::/2420b0:85ff:ffff:ffff:ffff:ffff:ffff:ffff
13520b0:8600::/2420b0:86ff:ffff:ffff:ffff:ffff:ffff:ffff
13620b0:8700::/2420b0:87ff:ffff:ffff:ffff:ffff:ffff:ffff
13720b0:8800::/2420b0:88ff:ffff:ffff:ffff:ffff:ffff:ffff
13820b0:8900::/2420b0:89ff:ffff:ffff:ffff:ffff:ffff:ffff
13920b0:8a00::/2420b0:8aff:ffff:ffff:ffff:ffff:ffff:ffff
14020b0:8b00::/2420b0:8bff:ffff:ffff:ffff:ffff:ffff:ffff
14120b0:8c00::/2420b0:8cff:ffff:ffff:ffff:ffff:ffff:ffff
14220b0:8d00::/2420b0:8dff:ffff:ffff:ffff:ffff:ffff:ffff
14320b0:8e00::/2420b0:8eff:ffff:ffff:ffff:ffff:ffff:ffff
14420b0:8f00::/2420b0:8fff:ffff:ffff:ffff:ffff:ffff:ffff
14520b0:9000::/2420b0:90ff:ffff:ffff:ffff:ffff:ffff:ffff
14620b0:9100::/2420b0:91ff:ffff:ffff:ffff:ffff:ffff:ffff
14720b0:9200::/2420b0:92ff:ffff:ffff:ffff:ffff:ffff:ffff
14820b0:9300::/2420b0:93ff:ffff:ffff:ffff:ffff:ffff:ffff
14920b0:9400::/2420b0:94ff:ffff:ffff:ffff:ffff:ffff:ffff
15020b0:9500::/2420b0:95ff:ffff:ffff:ffff:ffff:ffff:ffff
15120b0:9600::/2420b0:96ff:ffff:ffff:ffff:ffff:ffff:ffff
15220b0:9700::/2420b0:97ff:ffff:ffff:ffff:ffff:ffff:ffff
15320b0:9800::/2420b0:98ff:ffff:ffff:ffff:ffff:ffff:ffff
15420b0:9900::/2420b0:99ff:ffff:ffff:ffff:ffff:ffff:ffff
15520b0:9a00::/2420b0:9aff:ffff:ffff:ffff:ffff:ffff:ffff
15620b0:9b00::/2420b0:9bff:ffff:ffff:ffff:ffff:ffff:ffff
15720b0:9c00::/2420b0:9cff:ffff:ffff:ffff:ffff:ffff:ffff
15820b0:9d00::/2420b0:9dff:ffff:ffff:ffff:ffff:ffff:ffff
15920b0:9e00::/2420b0:9eff:ffff:ffff:ffff:ffff:ffff:ffff
16020b0:9f00::/2420b0:9fff:ffff:ffff:ffff:ffff:ffff:ffff
16120b0:a000::/2420b0:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
16220b0:a100::/2420b0:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
16320b0:a200::/2420b0:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
16420b0:a300::/2420b0:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
16520b0:a400::/2420b0:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
16620b0:a500::/2420b0:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
16720b0:a600::/2420b0:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
16820b0:a700::/2420b0:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
16920b0:a800::/2420b0:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
17020b0:a900::/2420b0:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
17120b0:aa00::/2420b0:aaff:ffff:ffff:ffff:ffff:ffff:ffff
17220b0:ab00::/2420b0:abff:ffff:ffff:ffff:ffff:ffff:ffff
17320b0:ac00::/2420b0:acff:ffff:ffff:ffff:ffff:ffff:ffff
17420b0:ad00::/2420b0:adff:ffff:ffff:ffff:ffff:ffff:ffff
17520b0:ae00::/2420b0:aeff:ffff:ffff:ffff:ffff:ffff:ffff
17620b0:af00::/2420b0:afff:ffff:ffff:ffff:ffff:ffff:ffff
17720b0:b000::/2420b0:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
17820b0:b100::/2420b0:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
17920b0:b200::/2420b0:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
18020b0:b300::/2420b0:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
18120b0:b400::/2420b0:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
18220b0:b500::/2420b0:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
18320b0:b600::/2420b0:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
18420b0:b700::/2420b0:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
18520b0:b800::/2420b0:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
18620b0:b900::/2420b0:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
18720b0:ba00::/2420b0:baff:ffff:ffff:ffff:ffff:ffff:ffff
18820b0:bb00::/2420b0:bbff:ffff:ffff:ffff:ffff:ffff:ffff
18920b0:bc00::/2420b0:bcff:ffff:ffff:ffff:ffff:ffff:ffff
19020b0:bd00::/2420b0:bdff:ffff:ffff:ffff:ffff:ffff:ffff
19120b0:be00::/2420b0:beff:ffff:ffff:ffff:ffff:ffff:ffff
19220b0:bf00::/2420b0:bfff:ffff:ffff:ffff:ffff:ffff:ffff
19320b0:c000::/2420b0:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
19420b0:c100::/2420b0:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
19520b0:c200::/2420b0:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
19620b0:c300::/2420b0:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
19720b0:c400::/2420b0:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
19820b0:c500::/2420b0:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
19920b0:c600::/2420b0:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
20020b0:c700::/2420b0:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
20120b0:c800::/2420b0:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
20220b0:c900::/2420b0:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
20320b0:ca00::/2420b0:caff:ffff:ffff:ffff:ffff:ffff:ffff
20420b0:cb00::/2420b0:cbff:ffff:ffff:ffff:ffff:ffff:ffff
20520b0:cc00::/2420b0:ccff:ffff:ffff:ffff:ffff:ffff:ffff
20620b0:cd00::/2420b0:cdff:ffff:ffff:ffff:ffff:ffff:ffff
20720b0:ce00::/2420b0:ceff:ffff:ffff:ffff:ffff:ffff:ffff
20820b0:cf00::/2420b0:cfff:ffff:ffff:ffff:ffff:ffff:ffff
20920b0:d000::/2420b0:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
21020b0:d100::/2420b0:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
21120b0:d200::/2420b0:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
21220b0:d300::/2420b0:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
21320b0:d400::/2420b0:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
21420b0:d500::/2420b0:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
21520b0:d600::/2420b0:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
21620b0:d700::/2420b0:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
21720b0:d800::/2420b0:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
21820b0:d900::/2420b0:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
21920b0:da00::/2420b0:daff:ffff:ffff:ffff:ffff:ffff:ffff
22020b0:db00::/2420b0:dbff:ffff:ffff:ffff:ffff:ffff:ffff
22120b0:dc00::/2420b0:dcff:ffff:ffff:ffff:ffff:ffff:ffff
22220b0:dd00::/2420b0:ddff:ffff:ffff:ffff:ffff:ffff:ffff
22320b0:de00::/2420b0:deff:ffff:ffff:ffff:ffff:ffff:ffff
22420b0:df00::/2420b0:dfff:ffff:ffff:ffff:ffff:ffff:ffff
22520b0:e000::/2420b0:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
22620b0:e100::/2420b0:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
22720b0:e200::/2420b0:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
22820b0:e300::/2420b0:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
22920b0:e400::/2420b0:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
23020b0:e500::/2420b0:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
23120b0:e600::/2420b0:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
23220b0:e700::/2420b0:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
23320b0:e800::/2420b0:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
23420b0:e900::/2420b0:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
23520b0:ea00::/2420b0:eaff:ffff:ffff:ffff:ffff:ffff:ffff
23620b0:eb00::/2420b0:ebff:ffff:ffff:ffff:ffff:ffff:ffff
23720b0:ec00::/2420b0:ecff:ffff:ffff:ffff:ffff:ffff:ffff
23820b0:ed00::/2420b0:edff:ffff:ffff:ffff:ffff:ffff:ffff
23920b0:ee00::/2420b0:eeff:ffff:ffff:ffff:ffff:ffff:ffff
24020b0:ef00::/2420b0:efff:ffff:ffff:ffff:ffff:ffff:ffff
24120b0:f000::/2420b0:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
24220b0:f100::/2420b0:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
24320b0:f200::/2420b0:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
24420b0:f300::/2420b0:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
24520b0:f400::/2420b0:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
24620b0:f500::/2420b0:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
24720b0:f600::/2420b0:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
24820b0:f700::/2420b0:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
24920b0:f800::/2420b0:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
25020b0:f900::/2420b0:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
25120b0:fa00::/2420b0:faff:ffff:ffff:ffff:ffff:ffff:ffff
25220b0:fb00::/2420b0:fbff:ffff:ffff:ffff:ffff:ffff:ffff
25320b0:fc00::/2420b0:fcff:ffff:ffff:ffff:ffff:ffff:ffff
25420b0:fd00::/2420b0:fdff:ffff:ffff:ffff:ffff:ffff:ffff
25520b0:fe00::/2420b0:feff:ffff:ffff:ffff:ffff:ffff:ffff
25620b0:ff00::/2420b0: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.