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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/7
Addresses2^121
/64 networks2^57
Network
3800::/7
First address
3800::
Last address
39ff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
2,658,455,991,569,831,745,807,614,120,560,689,152 (2^121)
/64 networks (LANs)
144,115,188,075,855,872 (2^57)
Full form
3800:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
8.3.ip6.arpa
9.3.ip6.arpa
/7 is not on a 4-bit boundary, so it takes 2 /8 zones.
Split into smaller subnets/16
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/16 (512)/20 (8,192)

3800::/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetLast address
13800::/163800:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23801::/163801:ffff:ffff:ffff:ffff:ffff:ffff:ffff
33802::/163802:ffff:ffff:ffff:ffff:ffff:ffff:ffff
43803::/163803:ffff:ffff:ffff:ffff:ffff:ffff:ffff
53804::/163804:ffff:ffff:ffff:ffff:ffff:ffff:ffff
63805::/163805:ffff:ffff:ffff:ffff:ffff:ffff:ffff
73806::/163806:ffff:ffff:ffff:ffff:ffff:ffff:ffff
83807::/163807:ffff:ffff:ffff:ffff:ffff:ffff:ffff
93808::/163808:ffff:ffff:ffff:ffff:ffff:ffff:ffff
103809::/163809:ffff:ffff:ffff:ffff:ffff:ffff:ffff
11380a::/16380a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
12380b::/16380b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
13380c::/16380c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
14380d::/16380d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
15380e::/16380e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16380f::/16380f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
173810::/163810:ffff:ffff:ffff:ffff:ffff:ffff:ffff
183811::/163811:ffff:ffff:ffff:ffff:ffff:ffff:ffff
193812::/163812:ffff:ffff:ffff:ffff:ffff:ffff:ffff
203813::/163813:ffff:ffff:ffff:ffff:ffff:ffff:ffff
213814::/163814:ffff:ffff:ffff:ffff:ffff:ffff:ffff
223815::/163815:ffff:ffff:ffff:ffff:ffff:ffff:ffff
233816::/163816:ffff:ffff:ffff:ffff:ffff:ffff:ffff
243817::/163817:ffff:ffff:ffff:ffff:ffff:ffff:ffff
253818::/163818:ffff:ffff:ffff:ffff:ffff:ffff:ffff
263819::/163819:ffff:ffff:ffff:ffff:ffff:ffff:ffff
27381a::/16381a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
28381b::/16381b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
29381c::/16381c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
30381d::/16381d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
31381e::/16381e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
32381f::/16381f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
333820::/163820:ffff:ffff:ffff:ffff:ffff:ffff:ffff
343821::/163821:ffff:ffff:ffff:ffff:ffff:ffff:ffff
353822::/163822:ffff:ffff:ffff:ffff:ffff:ffff:ffff
363823::/163823:ffff:ffff:ffff:ffff:ffff:ffff:ffff
373824::/163824:ffff:ffff:ffff:ffff:ffff:ffff:ffff
383825::/163825:ffff:ffff:ffff:ffff:ffff:ffff:ffff
393826::/163826:ffff:ffff:ffff:ffff:ffff:ffff:ffff
403827::/163827:ffff:ffff:ffff:ffff:ffff:ffff:ffff
413828::/163828:ffff:ffff:ffff:ffff:ffff:ffff:ffff
423829::/163829:ffff:ffff:ffff:ffff:ffff:ffff:ffff
43382a::/16382a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
44382b::/16382b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
45382c::/16382c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
46382d::/16382d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
47382e::/16382e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
48382f::/16382f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
493830::/163830:ffff:ffff:ffff:ffff:ffff:ffff:ffff
503831::/163831:ffff:ffff:ffff:ffff:ffff:ffff:ffff
513832::/163832:ffff:ffff:ffff:ffff:ffff:ffff:ffff
523833::/163833:ffff:ffff:ffff:ffff:ffff:ffff:ffff
533834::/163834:ffff:ffff:ffff:ffff:ffff:ffff:ffff
543835::/163835:ffff:ffff:ffff:ffff:ffff:ffff:ffff
553836::/163836:ffff:ffff:ffff:ffff:ffff:ffff:ffff
563837::/163837:ffff:ffff:ffff:ffff:ffff:ffff:ffff
573838::/163838:ffff:ffff:ffff:ffff:ffff:ffff:ffff
583839::/163839:ffff:ffff:ffff:ffff:ffff:ffff:ffff
59383a::/16383a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
60383b::/16383b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
61383c::/16383c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
62383d::/16383d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
63383e::/16383e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
64383f::/16383f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
653840::/163840:ffff:ffff:ffff:ffff:ffff:ffff:ffff
663841::/163841:ffff:ffff:ffff:ffff:ffff:ffff:ffff
673842::/163842:ffff:ffff:ffff:ffff:ffff:ffff:ffff
683843::/163843:ffff:ffff:ffff:ffff:ffff:ffff:ffff
693844::/163844:ffff:ffff:ffff:ffff:ffff:ffff:ffff
703845::/163845:ffff:ffff:ffff:ffff:ffff:ffff:ffff
713846::/163846:ffff:ffff:ffff:ffff:ffff:ffff:ffff
723847::/163847:ffff:ffff:ffff:ffff:ffff:ffff:ffff
733848::/163848:ffff:ffff:ffff:ffff:ffff:ffff:ffff
743849::/163849:ffff:ffff:ffff:ffff:ffff:ffff:ffff
75384a::/16384a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
76384b::/16384b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
77384c::/16384c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
78384d::/16384d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
79384e::/16384e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
80384f::/16384f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
813850::/163850:ffff:ffff:ffff:ffff:ffff:ffff:ffff
823851::/163851:ffff:ffff:ffff:ffff:ffff:ffff:ffff
833852::/163852:ffff:ffff:ffff:ffff:ffff:ffff:ffff
843853::/163853:ffff:ffff:ffff:ffff:ffff:ffff:ffff
853854::/163854:ffff:ffff:ffff:ffff:ffff:ffff:ffff
863855::/163855:ffff:ffff:ffff:ffff:ffff:ffff:ffff
873856::/163856:ffff:ffff:ffff:ffff:ffff:ffff:ffff
883857::/163857:ffff:ffff:ffff:ffff:ffff:ffff:ffff
893858::/163858:ffff:ffff:ffff:ffff:ffff:ffff:ffff
903859::/163859:ffff:ffff:ffff:ffff:ffff:ffff:ffff
91385a::/16385a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
92385b::/16385b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
93385c::/16385c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
94385d::/16385d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
95385e::/16385e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
96385f::/16385f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
973860::/163860:ffff:ffff:ffff:ffff:ffff:ffff:ffff
983861::/163861:ffff:ffff:ffff:ffff:ffff:ffff:ffff
993862::/163862:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1003863::/163863:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1013864::/163864:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1023865::/163865:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1033866::/163866:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1043867::/163867:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1053868::/163868:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1063869::/163869:ffff:ffff:ffff:ffff:ffff:ffff:ffff
107386a::/16386a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
108386b::/16386b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
109386c::/16386c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
110386d::/16386d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
111386e::/16386e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
112386f::/16386f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1133870::/163870:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1143871::/163871:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1153872::/163872:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1163873::/163873:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1173874::/163874:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1183875::/163875:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1193876::/163876:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1203877::/163877:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1213878::/163878:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1223879::/163879:ffff:ffff:ffff:ffff:ffff:ffff:ffff
123387a::/16387a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
124387b::/16387b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
125387c::/16387c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
126387d::/16387d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
127387e::/16387e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
128387f::/16387f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1293880::/163880:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1303881::/163881:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1313882::/163882:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1323883::/163883:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1333884::/163884:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1343885::/163885:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1353886::/163886:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1363887::/163887:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1373888::/163888:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1383889::/163889:ffff:ffff:ffff:ffff:ffff:ffff:ffff
139388a::/16388a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
140388b::/16388b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
141388c::/16388c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
142388d::/16388d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
143388e::/16388e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
144388f::/16388f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1453890::/163890:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1463891::/163891:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1473892::/163892:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1483893::/163893:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1493894::/163894:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1503895::/163895:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1513896::/163896:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1523897::/163897:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1533898::/163898:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1543899::/163899:ffff:ffff:ffff:ffff:ffff:ffff:ffff
155389a::/16389a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
156389b::/16389b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
157389c::/16389c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
158389d::/16389d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
159389e::/16389e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
160389f::/16389f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16138a0::/1638a0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16238a1::/1638a1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16338a2::/1638a2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16438a3::/1638a3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16538a4::/1638a4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16638a5::/1638a5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16738a6::/1638a6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16838a7::/1638a7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16938a8::/1638a8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17038a9::/1638a9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17138aa::/1638aa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17238ab::/1638ab:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17338ac::/1638ac:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17438ad::/1638ad:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17538ae::/1638ae:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17638af::/1638af:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17738b0::/1638b0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17838b1::/1638b1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17938b2::/1638b2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18038b3::/1638b3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18138b4::/1638b4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18238b5::/1638b5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18338b6::/1638b6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18438b7::/1638b7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18538b8::/1638b8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18638b9::/1638b9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18738ba::/1638ba:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18838bb::/1638bb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18938bc::/1638bc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19038bd::/1638bd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19138be::/1638be:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19238bf::/1638bf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19338c0::/1638c0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19438c1::/1638c1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19538c2::/1638c2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19638c3::/1638c3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19738c4::/1638c4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19838c5::/1638c5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19938c6::/1638c6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20038c7::/1638c7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20138c8::/1638c8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20238c9::/1638c9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20338ca::/1638ca:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20438cb::/1638cb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20538cc::/1638cc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20638cd::/1638cd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20738ce::/1638ce:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20838cf::/1638cf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20938d0::/1638d0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21038d1::/1638d1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21138d2::/1638d2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21238d3::/1638d3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21338d4::/1638d4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21438d5::/1638d5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21538d6::/1638d6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21638d7::/1638d7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21738d8::/1638d8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21838d9::/1638d9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21938da::/1638da:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22038db::/1638db:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22138dc::/1638dc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22238dd::/1638dd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22338de::/1638de:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22438df::/1638df:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22538e0::/1638e0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22638e1::/1638e1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22738e2::/1638e2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22838e3::/1638e3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22938e4::/1638e4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23038e5::/1638e5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23138e6::/1638e6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23238e7::/1638e7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23338e8::/1638e8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23438e9::/1638e9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23538ea::/1638ea:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23638eb::/1638eb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23738ec::/1638ec:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23838ed::/1638ed:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23938ee::/1638ee:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24038ef::/1638ef:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24138f0::/1638f0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24238f1::/1638f1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24338f2::/1638f2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24438f3::/1638f3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24538f4::/1638f4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24638f5::/1638f5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24738f6::/1638f6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24838f7::/1638f7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24938f8::/1638f8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25038f9::/1638f9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25138fa::/1638fa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25238fb::/1638fb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25338fc::/1638fc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25438fd::/1638fd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25538fe::/1638fe:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25638ff::/1638ff: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.