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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
3400::/7
First address
3400::
Last address
35ff: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
3400:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
4.3.ip6.arpa
5.3.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)

3400::/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetLast address
13400::/163400:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23401::/163401:ffff:ffff:ffff:ffff:ffff:ffff:ffff
33402::/163402:ffff:ffff:ffff:ffff:ffff:ffff:ffff
43403::/163403:ffff:ffff:ffff:ffff:ffff:ffff:ffff
53404::/163404:ffff:ffff:ffff:ffff:ffff:ffff:ffff
63405::/163405:ffff:ffff:ffff:ffff:ffff:ffff:ffff
73406::/163406:ffff:ffff:ffff:ffff:ffff:ffff:ffff
83407::/163407:ffff:ffff:ffff:ffff:ffff:ffff:ffff
93408::/163408:ffff:ffff:ffff:ffff:ffff:ffff:ffff
103409::/163409:ffff:ffff:ffff:ffff:ffff:ffff:ffff
11340a::/16340a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
12340b::/16340b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
13340c::/16340c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
14340d::/16340d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
15340e::/16340e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16340f::/16340f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
173410::/163410:ffff:ffff:ffff:ffff:ffff:ffff:ffff
183411::/163411:ffff:ffff:ffff:ffff:ffff:ffff:ffff
193412::/163412:ffff:ffff:ffff:ffff:ffff:ffff:ffff
203413::/163413:ffff:ffff:ffff:ffff:ffff:ffff:ffff
213414::/163414:ffff:ffff:ffff:ffff:ffff:ffff:ffff
223415::/163415:ffff:ffff:ffff:ffff:ffff:ffff:ffff
233416::/163416:ffff:ffff:ffff:ffff:ffff:ffff:ffff
243417::/163417:ffff:ffff:ffff:ffff:ffff:ffff:ffff
253418::/163418:ffff:ffff:ffff:ffff:ffff:ffff:ffff
263419::/163419:ffff:ffff:ffff:ffff:ffff:ffff:ffff
27341a::/16341a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
28341b::/16341b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
29341c::/16341c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
30341d::/16341d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
31341e::/16341e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
32341f::/16341f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
333420::/163420:ffff:ffff:ffff:ffff:ffff:ffff:ffff
343421::/163421:ffff:ffff:ffff:ffff:ffff:ffff:ffff
353422::/163422:ffff:ffff:ffff:ffff:ffff:ffff:ffff
363423::/163423:ffff:ffff:ffff:ffff:ffff:ffff:ffff
373424::/163424:ffff:ffff:ffff:ffff:ffff:ffff:ffff
383425::/163425:ffff:ffff:ffff:ffff:ffff:ffff:ffff
393426::/163426:ffff:ffff:ffff:ffff:ffff:ffff:ffff
403427::/163427:ffff:ffff:ffff:ffff:ffff:ffff:ffff
413428::/163428:ffff:ffff:ffff:ffff:ffff:ffff:ffff
423429::/163429:ffff:ffff:ffff:ffff:ffff:ffff:ffff
43342a::/16342a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
44342b::/16342b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
45342c::/16342c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
46342d::/16342d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
47342e::/16342e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
48342f::/16342f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
493430::/163430:ffff:ffff:ffff:ffff:ffff:ffff:ffff
503431::/163431:ffff:ffff:ffff:ffff:ffff:ffff:ffff
513432::/163432:ffff:ffff:ffff:ffff:ffff:ffff:ffff
523433::/163433:ffff:ffff:ffff:ffff:ffff:ffff:ffff
533434::/163434:ffff:ffff:ffff:ffff:ffff:ffff:ffff
543435::/163435:ffff:ffff:ffff:ffff:ffff:ffff:ffff
553436::/163436:ffff:ffff:ffff:ffff:ffff:ffff:ffff
563437::/163437:ffff:ffff:ffff:ffff:ffff:ffff:ffff
573438::/163438:ffff:ffff:ffff:ffff:ffff:ffff:ffff
583439::/163439:ffff:ffff:ffff:ffff:ffff:ffff:ffff
59343a::/16343a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
60343b::/16343b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
61343c::/16343c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
62343d::/16343d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
63343e::/16343e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
64343f::/16343f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
653440::/163440:ffff:ffff:ffff:ffff:ffff:ffff:ffff
663441::/163441:ffff:ffff:ffff:ffff:ffff:ffff:ffff
673442::/163442:ffff:ffff:ffff:ffff:ffff:ffff:ffff
683443::/163443:ffff:ffff:ffff:ffff:ffff:ffff:ffff
693444::/163444:ffff:ffff:ffff:ffff:ffff:ffff:ffff
703445::/163445:ffff:ffff:ffff:ffff:ffff:ffff:ffff
713446::/163446:ffff:ffff:ffff:ffff:ffff:ffff:ffff
723447::/163447:ffff:ffff:ffff:ffff:ffff:ffff:ffff
733448::/163448:ffff:ffff:ffff:ffff:ffff:ffff:ffff
743449::/163449:ffff:ffff:ffff:ffff:ffff:ffff:ffff
75344a::/16344a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
76344b::/16344b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
77344c::/16344c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
78344d::/16344d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
79344e::/16344e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
80344f::/16344f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
813450::/163450:ffff:ffff:ffff:ffff:ffff:ffff:ffff
823451::/163451:ffff:ffff:ffff:ffff:ffff:ffff:ffff
833452::/163452:ffff:ffff:ffff:ffff:ffff:ffff:ffff
843453::/163453:ffff:ffff:ffff:ffff:ffff:ffff:ffff
853454::/163454:ffff:ffff:ffff:ffff:ffff:ffff:ffff
863455::/163455:ffff:ffff:ffff:ffff:ffff:ffff:ffff
873456::/163456:ffff:ffff:ffff:ffff:ffff:ffff:ffff
883457::/163457:ffff:ffff:ffff:ffff:ffff:ffff:ffff
893458::/163458:ffff:ffff:ffff:ffff:ffff:ffff:ffff
903459::/163459:ffff:ffff:ffff:ffff:ffff:ffff:ffff
91345a::/16345a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
92345b::/16345b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
93345c::/16345c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
94345d::/16345d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
95345e::/16345e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
96345f::/16345f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
973460::/163460:ffff:ffff:ffff:ffff:ffff:ffff:ffff
983461::/163461:ffff:ffff:ffff:ffff:ffff:ffff:ffff
993462::/163462:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1003463::/163463:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1013464::/163464:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1023465::/163465:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1033466::/163466:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1043467::/163467:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1053468::/163468:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1063469::/163469:ffff:ffff:ffff:ffff:ffff:ffff:ffff
107346a::/16346a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
108346b::/16346b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
109346c::/16346c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
110346d::/16346d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
111346e::/16346e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
112346f::/16346f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1133470::/163470:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1143471::/163471:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1153472::/163472:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1163473::/163473:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1173474::/163474:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1183475::/163475:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1193476::/163476:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1203477::/163477:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1213478::/163478:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1223479::/163479:ffff:ffff:ffff:ffff:ffff:ffff:ffff
123347a::/16347a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
124347b::/16347b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
125347c::/16347c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
126347d::/16347d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
127347e::/16347e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
128347f::/16347f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1293480::/163480:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1303481::/163481:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1313482::/163482:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1323483::/163483:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1333484::/163484:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1343485::/163485:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1353486::/163486:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1363487::/163487:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1373488::/163488:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1383489::/163489:ffff:ffff:ffff:ffff:ffff:ffff:ffff
139348a::/16348a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
140348b::/16348b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
141348c::/16348c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
142348d::/16348d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
143348e::/16348e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
144348f::/16348f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1453490::/163490:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1463491::/163491:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1473492::/163492:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1483493::/163493:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1493494::/163494:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1503495::/163495:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1513496::/163496:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1523497::/163497:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1533498::/163498:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1543499::/163499:ffff:ffff:ffff:ffff:ffff:ffff:ffff
155349a::/16349a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
156349b::/16349b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
157349c::/16349c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
158349d::/16349d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
159349e::/16349e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
160349f::/16349f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16134a0::/1634a0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16234a1::/1634a1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16334a2::/1634a2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16434a3::/1634a3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16534a4::/1634a4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16634a5::/1634a5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16734a6::/1634a6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16834a7::/1634a7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16934a8::/1634a8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17034a9::/1634a9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17134aa::/1634aa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17234ab::/1634ab:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17334ac::/1634ac:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17434ad::/1634ad:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17534ae::/1634ae:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17634af::/1634af:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17734b0::/1634b0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17834b1::/1634b1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17934b2::/1634b2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18034b3::/1634b3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18134b4::/1634b4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18234b5::/1634b5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18334b6::/1634b6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18434b7::/1634b7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18534b8::/1634b8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18634b9::/1634b9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18734ba::/1634ba:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18834bb::/1634bb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18934bc::/1634bc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19034bd::/1634bd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19134be::/1634be:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19234bf::/1634bf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19334c0::/1634c0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19434c1::/1634c1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19534c2::/1634c2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19634c3::/1634c3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19734c4::/1634c4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19834c5::/1634c5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19934c6::/1634c6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20034c7::/1634c7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20134c8::/1634c8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20234c9::/1634c9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20334ca::/1634ca:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20434cb::/1634cb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20534cc::/1634cc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20634cd::/1634cd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20734ce::/1634ce:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20834cf::/1634cf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20934d0::/1634d0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21034d1::/1634d1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21134d2::/1634d2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21234d3::/1634d3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21334d4::/1634d4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21434d5::/1634d5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21534d6::/1634d6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21634d7::/1634d7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21734d8::/1634d8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21834d9::/1634d9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21934da::/1634da:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22034db::/1634db:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22134dc::/1634dc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22234dd::/1634dd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22334de::/1634de:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22434df::/1634df:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22534e0::/1634e0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22634e1::/1634e1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22734e2::/1634e2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22834e3::/1634e3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22934e4::/1634e4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23034e5::/1634e5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23134e6::/1634e6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23234e7::/1634e7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23334e8::/1634e8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23434e9::/1634e9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23534ea::/1634ea:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23634eb::/1634eb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23734ec::/1634ec:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23834ed::/1634ed:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23934ee::/1634ee:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24034ef::/1634ef:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24134f0::/1634f0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24234f1::/1634f1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24334f2::/1634f2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24434f3::/1634f3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24534f4::/1634f4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24634f5::/1634f5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24734f6::/1634f6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24834f7::/1634f7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24934f8::/1634f8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25034f9::/1634f9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25134fa::/1634fa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25234fb::/1634fb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25334fc::/1634fc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25434fd::/1634fd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25534fe::/1634fe:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25634ff::/1634ff: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.