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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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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
2400::/7
First address
2400::
Last address
25ff: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
2400:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
4.2.ip6.arpa
5.2.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)

2400::/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetLast address
12400::/162400:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22401::/162401:ffff:ffff:ffff:ffff:ffff:ffff:ffff
32402::/162402:ffff:ffff:ffff:ffff:ffff:ffff:ffff
42403::/162403:ffff:ffff:ffff:ffff:ffff:ffff:ffff
52404::/162404:ffff:ffff:ffff:ffff:ffff:ffff:ffff
62405::/162405:ffff:ffff:ffff:ffff:ffff:ffff:ffff
72406::/162406:ffff:ffff:ffff:ffff:ffff:ffff:ffff
82407::/162407:ffff:ffff:ffff:ffff:ffff:ffff:ffff
92408::/162408:ffff:ffff:ffff:ffff:ffff:ffff:ffff
102409::/162409:ffff:ffff:ffff:ffff:ffff:ffff:ffff
11240a::/16240a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
12240b::/16240b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
13240c::/16240c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
14240d::/16240d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
15240e::/16240e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16240f::/16240f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
172410::/162410:ffff:ffff:ffff:ffff:ffff:ffff:ffff
182411::/162411:ffff:ffff:ffff:ffff:ffff:ffff:ffff
192412::/162412:ffff:ffff:ffff:ffff:ffff:ffff:ffff
202413::/162413:ffff:ffff:ffff:ffff:ffff:ffff:ffff
212414::/162414:ffff:ffff:ffff:ffff:ffff:ffff:ffff
222415::/162415:ffff:ffff:ffff:ffff:ffff:ffff:ffff
232416::/162416:ffff:ffff:ffff:ffff:ffff:ffff:ffff
242417::/162417:ffff:ffff:ffff:ffff:ffff:ffff:ffff
252418::/162418:ffff:ffff:ffff:ffff:ffff:ffff:ffff
262419::/162419:ffff:ffff:ffff:ffff:ffff:ffff:ffff
27241a::/16241a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
28241b::/16241b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
29241c::/16241c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
30241d::/16241d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
31241e::/16241e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
32241f::/16241f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
332420::/162420:ffff:ffff:ffff:ffff:ffff:ffff:ffff
342421::/162421:ffff:ffff:ffff:ffff:ffff:ffff:ffff
352422::/162422:ffff:ffff:ffff:ffff:ffff:ffff:ffff
362423::/162423:ffff:ffff:ffff:ffff:ffff:ffff:ffff
372424::/162424:ffff:ffff:ffff:ffff:ffff:ffff:ffff
382425::/162425:ffff:ffff:ffff:ffff:ffff:ffff:ffff
392426::/162426:ffff:ffff:ffff:ffff:ffff:ffff:ffff
402427::/162427:ffff:ffff:ffff:ffff:ffff:ffff:ffff
412428::/162428:ffff:ffff:ffff:ffff:ffff:ffff:ffff
422429::/162429:ffff:ffff:ffff:ffff:ffff:ffff:ffff
43242a::/16242a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
44242b::/16242b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
45242c::/16242c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
46242d::/16242d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
47242e::/16242e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
48242f::/16242f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
492430::/162430:ffff:ffff:ffff:ffff:ffff:ffff:ffff
502431::/162431:ffff:ffff:ffff:ffff:ffff:ffff:ffff
512432::/162432:ffff:ffff:ffff:ffff:ffff:ffff:ffff
522433::/162433:ffff:ffff:ffff:ffff:ffff:ffff:ffff
532434::/162434:ffff:ffff:ffff:ffff:ffff:ffff:ffff
542435::/162435:ffff:ffff:ffff:ffff:ffff:ffff:ffff
552436::/162436:ffff:ffff:ffff:ffff:ffff:ffff:ffff
562437::/162437:ffff:ffff:ffff:ffff:ffff:ffff:ffff
572438::/162438:ffff:ffff:ffff:ffff:ffff:ffff:ffff
582439::/162439:ffff:ffff:ffff:ffff:ffff:ffff:ffff
59243a::/16243a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
60243b::/16243b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
61243c::/16243c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
62243d::/16243d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
63243e::/16243e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
64243f::/16243f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
652440::/162440:ffff:ffff:ffff:ffff:ffff:ffff:ffff
662441::/162441:ffff:ffff:ffff:ffff:ffff:ffff:ffff
672442::/162442:ffff:ffff:ffff:ffff:ffff:ffff:ffff
682443::/162443:ffff:ffff:ffff:ffff:ffff:ffff:ffff
692444::/162444:ffff:ffff:ffff:ffff:ffff:ffff:ffff
702445::/162445:ffff:ffff:ffff:ffff:ffff:ffff:ffff
712446::/162446:ffff:ffff:ffff:ffff:ffff:ffff:ffff
722447::/162447:ffff:ffff:ffff:ffff:ffff:ffff:ffff
732448::/162448:ffff:ffff:ffff:ffff:ffff:ffff:ffff
742449::/162449:ffff:ffff:ffff:ffff:ffff:ffff:ffff
75244a::/16244a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
76244b::/16244b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
77244c::/16244c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
78244d::/16244d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
79244e::/16244e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
80244f::/16244f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
812450::/162450:ffff:ffff:ffff:ffff:ffff:ffff:ffff
822451::/162451:ffff:ffff:ffff:ffff:ffff:ffff:ffff
832452::/162452:ffff:ffff:ffff:ffff:ffff:ffff:ffff
842453::/162453:ffff:ffff:ffff:ffff:ffff:ffff:ffff
852454::/162454:ffff:ffff:ffff:ffff:ffff:ffff:ffff
862455::/162455:ffff:ffff:ffff:ffff:ffff:ffff:ffff
872456::/162456:ffff:ffff:ffff:ffff:ffff:ffff:ffff
882457::/162457:ffff:ffff:ffff:ffff:ffff:ffff:ffff
892458::/162458:ffff:ffff:ffff:ffff:ffff:ffff:ffff
902459::/162459:ffff:ffff:ffff:ffff:ffff:ffff:ffff
91245a::/16245a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
92245b::/16245b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
93245c::/16245c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
94245d::/16245d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
95245e::/16245e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
96245f::/16245f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
972460::/162460:ffff:ffff:ffff:ffff:ffff:ffff:ffff
982461::/162461:ffff:ffff:ffff:ffff:ffff:ffff:ffff
992462::/162462:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1002463::/162463:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1012464::/162464:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1022465::/162465:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1032466::/162466:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1042467::/162467:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1052468::/162468:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1062469::/162469:ffff:ffff:ffff:ffff:ffff:ffff:ffff
107246a::/16246a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
108246b::/16246b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
109246c::/16246c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
110246d::/16246d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
111246e::/16246e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
112246f::/16246f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1132470::/162470:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1142471::/162471:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1152472::/162472:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1162473::/162473:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1172474::/162474:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1182475::/162475:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1192476::/162476:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1202477::/162477:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1212478::/162478:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1222479::/162479:ffff:ffff:ffff:ffff:ffff:ffff:ffff
123247a::/16247a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
124247b::/16247b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
125247c::/16247c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
126247d::/16247d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
127247e::/16247e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
128247f::/16247f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1292480::/162480:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1302481::/162481:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1312482::/162482:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1322483::/162483:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1332484::/162484:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1342485::/162485:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1352486::/162486:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1362487::/162487:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1372488::/162488:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1382489::/162489:ffff:ffff:ffff:ffff:ffff:ffff:ffff
139248a::/16248a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
140248b::/16248b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
141248c::/16248c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
142248d::/16248d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
143248e::/16248e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
144248f::/16248f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1452490::/162490:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1462491::/162491:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1472492::/162492:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1482493::/162493:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1492494::/162494:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1502495::/162495:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1512496::/162496:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1522497::/162497:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1532498::/162498:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1542499::/162499:ffff:ffff:ffff:ffff:ffff:ffff:ffff
155249a::/16249a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
156249b::/16249b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
157249c::/16249c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
158249d::/16249d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
159249e::/16249e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
160249f::/16249f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16124a0::/1624a0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16224a1::/1624a1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16324a2::/1624a2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16424a3::/1624a3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16524a4::/1624a4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16624a5::/1624a5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16724a6::/1624a6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16824a7::/1624a7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
16924a8::/1624a8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17024a9::/1624a9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17124aa::/1624aa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17224ab::/1624ab:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17324ac::/1624ac:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17424ad::/1624ad:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17524ae::/1624ae:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17624af::/1624af:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17724b0::/1624b0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17824b1::/1624b1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17924b2::/1624b2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18024b3::/1624b3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18124b4::/1624b4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18224b5::/1624b5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18324b6::/1624b6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18424b7::/1624b7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18524b8::/1624b8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18624b9::/1624b9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18724ba::/1624ba:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18824bb::/1624bb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
18924bc::/1624bc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19024bd::/1624bd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19124be::/1624be:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19224bf::/1624bf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19324c0::/1624c0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19424c1::/1624c1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19524c2::/1624c2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19624c3::/1624c3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19724c4::/1624c4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19824c5::/1624c5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
19924c6::/1624c6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20024c7::/1624c7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20124c8::/1624c8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20224c9::/1624c9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20324ca::/1624ca:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20424cb::/1624cb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20524cc::/1624cc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20624cd::/1624cd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20724ce::/1624ce:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20824cf::/1624cf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
20924d0::/1624d0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21024d1::/1624d1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21124d2::/1624d2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21224d3::/1624d3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21324d4::/1624d4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21424d5::/1624d5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21524d6::/1624d6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21624d7::/1624d7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21724d8::/1624d8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21824d9::/1624d9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
21924da::/1624da:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22024db::/1624db:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22124dc::/1624dc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22224dd::/1624dd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22324de::/1624de:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22424df::/1624df:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22524e0::/1624e0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22624e1::/1624e1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22724e2::/1624e2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22824e3::/1624e3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
22924e4::/1624e4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23024e5::/1624e5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23124e6::/1624e6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23224e7::/1624e7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23324e8::/1624e8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23424e9::/1624e9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23524ea::/1624ea:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23624eb::/1624eb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23724ec::/1624ec:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23824ed::/1624ed:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23924ee::/1624ee:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24024ef::/1624ef:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24124f0::/1624f0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24224f1::/1624f1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24324f2::/1624f2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24424f3::/1624f3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24524f4::/1624f4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24624f5::/1624f5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24724f6::/1624f6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24824f7::/1624f7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
24924f8::/1624f8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25024f9::/1624f9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25124fa::/1624fa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25224fb::/1624fb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25324fc::/1624fc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25424fd::/1624fd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25524fe::/1624fe:ffff:ffff:ffff:ffff:ffff:ffff:ffff
25624ff::/1624ff: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.