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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/12
Addresses2^116
/64 networks2^52
Network
25a0::/12
First address
25a0::
Last address
25af:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
83,076,749,736,557,242,056,487,941,267,521,536 (2^116)
/64 networks (LANs)
4,503,599,627,370,496 (2^52)
Full form
25a0:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
a.5.2.ip6.arpa
Split into smaller subnets/28
/13 (2)/14 (4)/15 (8)/16 (16)/20 (256)/24 (4,096)/28 (65,536)

25a0::/12 makes 65,536 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
125a0::/2825a0:f:ffff:ffff:ffff:ffff:ffff:ffff
225a0:10::/2825a0:1f:ffff:ffff:ffff:ffff:ffff:ffff
325a0:20::/2825a0:2f:ffff:ffff:ffff:ffff:ffff:ffff
425a0:30::/2825a0:3f:ffff:ffff:ffff:ffff:ffff:ffff
525a0:40::/2825a0:4f:ffff:ffff:ffff:ffff:ffff:ffff
625a0:50::/2825a0:5f:ffff:ffff:ffff:ffff:ffff:ffff
725a0:60::/2825a0:6f:ffff:ffff:ffff:ffff:ffff:ffff
825a0:70::/2825a0:7f:ffff:ffff:ffff:ffff:ffff:ffff
925a0:80::/2825a0:8f:ffff:ffff:ffff:ffff:ffff:ffff
1025a0:90::/2825a0:9f:ffff:ffff:ffff:ffff:ffff:ffff
1125a0:a0::/2825a0:af:ffff:ffff:ffff:ffff:ffff:ffff
1225a0:b0::/2825a0:bf:ffff:ffff:ffff:ffff:ffff:ffff
1325a0:c0::/2825a0:cf:ffff:ffff:ffff:ffff:ffff:ffff
1425a0:d0::/2825a0:df:ffff:ffff:ffff:ffff:ffff:ffff
1525a0:e0::/2825a0:ef:ffff:ffff:ffff:ffff:ffff:ffff
1625a0:f0::/2825a0:ff:ffff:ffff:ffff:ffff:ffff:ffff
1725a0:100::/2825a0:10f:ffff:ffff:ffff:ffff:ffff:ffff
1825a0:110::/2825a0:11f:ffff:ffff:ffff:ffff:ffff:ffff
1925a0:120::/2825a0:12f:ffff:ffff:ffff:ffff:ffff:ffff
2025a0:130::/2825a0:13f:ffff:ffff:ffff:ffff:ffff:ffff
2125a0:140::/2825a0:14f:ffff:ffff:ffff:ffff:ffff:ffff
2225a0:150::/2825a0:15f:ffff:ffff:ffff:ffff:ffff:ffff
2325a0:160::/2825a0:16f:ffff:ffff:ffff:ffff:ffff:ffff
2425a0:170::/2825a0:17f:ffff:ffff:ffff:ffff:ffff:ffff
2525a0:180::/2825a0:18f:ffff:ffff:ffff:ffff:ffff:ffff
2625a0:190::/2825a0:19f:ffff:ffff:ffff:ffff:ffff:ffff
2725a0:1a0::/2825a0:1af:ffff:ffff:ffff:ffff:ffff:ffff
2825a0:1b0::/2825a0:1bf:ffff:ffff:ffff:ffff:ffff:ffff
2925a0:1c0::/2825a0:1cf:ffff:ffff:ffff:ffff:ffff:ffff
3025a0:1d0::/2825a0:1df:ffff:ffff:ffff:ffff:ffff:ffff
3125a0:1e0::/2825a0:1ef:ffff:ffff:ffff:ffff:ffff:ffff
3225a0:1f0::/2825a0:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3325a0:200::/2825a0:20f:ffff:ffff:ffff:ffff:ffff:ffff
3425a0:210::/2825a0:21f:ffff:ffff:ffff:ffff:ffff:ffff
3525a0:220::/2825a0:22f:ffff:ffff:ffff:ffff:ffff:ffff
3625a0:230::/2825a0:23f:ffff:ffff:ffff:ffff:ffff:ffff
3725a0:240::/2825a0:24f:ffff:ffff:ffff:ffff:ffff:ffff
3825a0:250::/2825a0:25f:ffff:ffff:ffff:ffff:ffff:ffff
3925a0:260::/2825a0:26f:ffff:ffff:ffff:ffff:ffff:ffff
4025a0:270::/2825a0:27f:ffff:ffff:ffff:ffff:ffff:ffff
4125a0:280::/2825a0:28f:ffff:ffff:ffff:ffff:ffff:ffff
4225a0:290::/2825a0:29f:ffff:ffff:ffff:ffff:ffff:ffff
4325a0:2a0::/2825a0:2af:ffff:ffff:ffff:ffff:ffff:ffff
4425a0:2b0::/2825a0:2bf:ffff:ffff:ffff:ffff:ffff:ffff
4525a0:2c0::/2825a0:2cf:ffff:ffff:ffff:ffff:ffff:ffff
4625a0:2d0::/2825a0:2df:ffff:ffff:ffff:ffff:ffff:ffff
4725a0:2e0::/2825a0:2ef:ffff:ffff:ffff:ffff:ffff:ffff
4825a0:2f0::/2825a0:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4925a0:300::/2825a0:30f:ffff:ffff:ffff:ffff:ffff:ffff
5025a0:310::/2825a0:31f:ffff:ffff:ffff:ffff:ffff:ffff
5125a0:320::/2825a0:32f:ffff:ffff:ffff:ffff:ffff:ffff
5225a0:330::/2825a0:33f:ffff:ffff:ffff:ffff:ffff:ffff
5325a0:340::/2825a0:34f:ffff:ffff:ffff:ffff:ffff:ffff
5425a0:350::/2825a0:35f:ffff:ffff:ffff:ffff:ffff:ffff
5525a0:360::/2825a0:36f:ffff:ffff:ffff:ffff:ffff:ffff
5625a0:370::/2825a0:37f:ffff:ffff:ffff:ffff:ffff:ffff
5725a0:380::/2825a0:38f:ffff:ffff:ffff:ffff:ffff:ffff
5825a0:390::/2825a0:39f:ffff:ffff:ffff:ffff:ffff:ffff
5925a0:3a0::/2825a0:3af:ffff:ffff:ffff:ffff:ffff:ffff
6025a0:3b0::/2825a0:3bf:ffff:ffff:ffff:ffff:ffff:ffff
6125a0:3c0::/2825a0:3cf:ffff:ffff:ffff:ffff:ffff:ffff
6225a0:3d0::/2825a0:3df:ffff:ffff:ffff:ffff:ffff:ffff
6325a0:3e0::/2825a0:3ef:ffff:ffff:ffff:ffff:ffff:ffff
6425a0:3f0::/2825a0:3ff:ffff:ffff:ffff:ffff:ffff:ffff
6525a0:400::/2825a0:40f:ffff:ffff:ffff:ffff:ffff:ffff
6625a0:410::/2825a0:41f:ffff:ffff:ffff:ffff:ffff:ffff
6725a0:420::/2825a0:42f:ffff:ffff:ffff:ffff:ffff:ffff
6825a0:430::/2825a0:43f:ffff:ffff:ffff:ffff:ffff:ffff
6925a0:440::/2825a0:44f:ffff:ffff:ffff:ffff:ffff:ffff
7025a0:450::/2825a0:45f:ffff:ffff:ffff:ffff:ffff:ffff
7125a0:460::/2825a0:46f:ffff:ffff:ffff:ffff:ffff:ffff
7225a0:470::/2825a0:47f:ffff:ffff:ffff:ffff:ffff:ffff
7325a0:480::/2825a0:48f:ffff:ffff:ffff:ffff:ffff:ffff
7425a0:490::/2825a0:49f:ffff:ffff:ffff:ffff:ffff:ffff
7525a0:4a0::/2825a0:4af:ffff:ffff:ffff:ffff:ffff:ffff
7625a0:4b0::/2825a0:4bf:ffff:ffff:ffff:ffff:ffff:ffff
7725a0:4c0::/2825a0:4cf:ffff:ffff:ffff:ffff:ffff:ffff
7825a0:4d0::/2825a0:4df:ffff:ffff:ffff:ffff:ffff:ffff
7925a0:4e0::/2825a0:4ef:ffff:ffff:ffff:ffff:ffff:ffff
8025a0:4f0::/2825a0:4ff:ffff:ffff:ffff:ffff:ffff:ffff
8125a0:500::/2825a0:50f:ffff:ffff:ffff:ffff:ffff:ffff
8225a0:510::/2825a0:51f:ffff:ffff:ffff:ffff:ffff:ffff
8325a0:520::/2825a0:52f:ffff:ffff:ffff:ffff:ffff:ffff
8425a0:530::/2825a0:53f:ffff:ffff:ffff:ffff:ffff:ffff
8525a0:540::/2825a0:54f:ffff:ffff:ffff:ffff:ffff:ffff
8625a0:550::/2825a0:55f:ffff:ffff:ffff:ffff:ffff:ffff
8725a0:560::/2825a0:56f:ffff:ffff:ffff:ffff:ffff:ffff
8825a0:570::/2825a0:57f:ffff:ffff:ffff:ffff:ffff:ffff
8925a0:580::/2825a0:58f:ffff:ffff:ffff:ffff:ffff:ffff
9025a0:590::/2825a0:59f:ffff:ffff:ffff:ffff:ffff:ffff
9125a0:5a0::/2825a0:5af:ffff:ffff:ffff:ffff:ffff:ffff
9225a0:5b0::/2825a0:5bf:ffff:ffff:ffff:ffff:ffff:ffff
9325a0:5c0::/2825a0:5cf:ffff:ffff:ffff:ffff:ffff:ffff
9425a0:5d0::/2825a0:5df:ffff:ffff:ffff:ffff:ffff:ffff
9525a0:5e0::/2825a0:5ef:ffff:ffff:ffff:ffff:ffff:ffff
9625a0:5f0::/2825a0:5ff:ffff:ffff:ffff:ffff:ffff:ffff
9725a0:600::/2825a0:60f:ffff:ffff:ffff:ffff:ffff:ffff
9825a0:610::/2825a0:61f:ffff:ffff:ffff:ffff:ffff:ffff
9925a0:620::/2825a0:62f:ffff:ffff:ffff:ffff:ffff:ffff
10025a0:630::/2825a0:63f:ffff:ffff:ffff:ffff:ffff:ffff
10125a0:640::/2825a0:64f:ffff:ffff:ffff:ffff:ffff:ffff
10225a0:650::/2825a0:65f:ffff:ffff:ffff:ffff:ffff:ffff
10325a0:660::/2825a0:66f:ffff:ffff:ffff:ffff:ffff:ffff
10425a0:670::/2825a0:67f:ffff:ffff:ffff:ffff:ffff:ffff
10525a0:680::/2825a0:68f:ffff:ffff:ffff:ffff:ffff:ffff
10625a0:690::/2825a0:69f:ffff:ffff:ffff:ffff:ffff:ffff
10725a0:6a0::/2825a0:6af:ffff:ffff:ffff:ffff:ffff:ffff
10825a0:6b0::/2825a0:6bf:ffff:ffff:ffff:ffff:ffff:ffff
10925a0:6c0::/2825a0:6cf:ffff:ffff:ffff:ffff:ffff:ffff
11025a0:6d0::/2825a0:6df:ffff:ffff:ffff:ffff:ffff:ffff
11125a0:6e0::/2825a0:6ef:ffff:ffff:ffff:ffff:ffff:ffff
11225a0:6f0::/2825a0:6ff:ffff:ffff:ffff:ffff:ffff:ffff
11325a0:700::/2825a0:70f:ffff:ffff:ffff:ffff:ffff:ffff
11425a0:710::/2825a0:71f:ffff:ffff:ffff:ffff:ffff:ffff
11525a0:720::/2825a0:72f:ffff:ffff:ffff:ffff:ffff:ffff
11625a0:730::/2825a0:73f:ffff:ffff:ffff:ffff:ffff:ffff
11725a0:740::/2825a0:74f:ffff:ffff:ffff:ffff:ffff:ffff
11825a0:750::/2825a0:75f:ffff:ffff:ffff:ffff:ffff:ffff
11925a0:760::/2825a0:76f:ffff:ffff:ffff:ffff:ffff:ffff
12025a0:770::/2825a0:77f:ffff:ffff:ffff:ffff:ffff:ffff
12125a0:780::/2825a0:78f:ffff:ffff:ffff:ffff:ffff:ffff
12225a0:790::/2825a0:79f:ffff:ffff:ffff:ffff:ffff:ffff
12325a0:7a0::/2825a0:7af:ffff:ffff:ffff:ffff:ffff:ffff
12425a0:7b0::/2825a0:7bf:ffff:ffff:ffff:ffff:ffff:ffff
12525a0:7c0::/2825a0:7cf:ffff:ffff:ffff:ffff:ffff:ffff
12625a0:7d0::/2825a0:7df:ffff:ffff:ffff:ffff:ffff:ffff
12725a0:7e0::/2825a0:7ef:ffff:ffff:ffff:ffff:ffff:ffff
12825a0:7f0::/2825a0:7ff:ffff:ffff:ffff:ffff:ffff:ffff
12925a0:800::/2825a0:80f:ffff:ffff:ffff:ffff:ffff:ffff
13025a0:810::/2825a0:81f:ffff:ffff:ffff:ffff:ffff:ffff
13125a0:820::/2825a0:82f:ffff:ffff:ffff:ffff:ffff:ffff
13225a0:830::/2825a0:83f:ffff:ffff:ffff:ffff:ffff:ffff
13325a0:840::/2825a0:84f:ffff:ffff:ffff:ffff:ffff:ffff
13425a0:850::/2825a0:85f:ffff:ffff:ffff:ffff:ffff:ffff
13525a0:860::/2825a0:86f:ffff:ffff:ffff:ffff:ffff:ffff
13625a0:870::/2825a0:87f:ffff:ffff:ffff:ffff:ffff:ffff
13725a0:880::/2825a0:88f:ffff:ffff:ffff:ffff:ffff:ffff
13825a0:890::/2825a0:89f:ffff:ffff:ffff:ffff:ffff:ffff
13925a0:8a0::/2825a0:8af:ffff:ffff:ffff:ffff:ffff:ffff
14025a0:8b0::/2825a0:8bf:ffff:ffff:ffff:ffff:ffff:ffff
14125a0:8c0::/2825a0:8cf:ffff:ffff:ffff:ffff:ffff:ffff
14225a0:8d0::/2825a0:8df:ffff:ffff:ffff:ffff:ffff:ffff
14325a0:8e0::/2825a0:8ef:ffff:ffff:ffff:ffff:ffff:ffff
14425a0:8f0::/2825a0:8ff:ffff:ffff:ffff:ffff:ffff:ffff
14525a0:900::/2825a0:90f:ffff:ffff:ffff:ffff:ffff:ffff
14625a0:910::/2825a0:91f:ffff:ffff:ffff:ffff:ffff:ffff
14725a0:920::/2825a0:92f:ffff:ffff:ffff:ffff:ffff:ffff
14825a0:930::/2825a0:93f:ffff:ffff:ffff:ffff:ffff:ffff
14925a0:940::/2825a0:94f:ffff:ffff:ffff:ffff:ffff:ffff
15025a0:950::/2825a0:95f:ffff:ffff:ffff:ffff:ffff:ffff
15125a0:960::/2825a0:96f:ffff:ffff:ffff:ffff:ffff:ffff
15225a0:970::/2825a0:97f:ffff:ffff:ffff:ffff:ffff:ffff
15325a0:980::/2825a0:98f:ffff:ffff:ffff:ffff:ffff:ffff
15425a0:990::/2825a0:99f:ffff:ffff:ffff:ffff:ffff:ffff
15525a0:9a0::/2825a0:9af:ffff:ffff:ffff:ffff:ffff:ffff
15625a0:9b0::/2825a0:9bf:ffff:ffff:ffff:ffff:ffff:ffff
15725a0:9c0::/2825a0:9cf:ffff:ffff:ffff:ffff:ffff:ffff
15825a0:9d0::/2825a0:9df:ffff:ffff:ffff:ffff:ffff:ffff
15925a0:9e0::/2825a0:9ef:ffff:ffff:ffff:ffff:ffff:ffff
16025a0:9f0::/2825a0:9ff:ffff:ffff:ffff:ffff:ffff:ffff
16125a0:a00::/2825a0:a0f:ffff:ffff:ffff:ffff:ffff:ffff
16225a0:a10::/2825a0:a1f:ffff:ffff:ffff:ffff:ffff:ffff
16325a0:a20::/2825a0:a2f:ffff:ffff:ffff:ffff:ffff:ffff
16425a0:a30::/2825a0:a3f:ffff:ffff:ffff:ffff:ffff:ffff
16525a0:a40::/2825a0:a4f:ffff:ffff:ffff:ffff:ffff:ffff
16625a0:a50::/2825a0:a5f:ffff:ffff:ffff:ffff:ffff:ffff
16725a0:a60::/2825a0:a6f:ffff:ffff:ffff:ffff:ffff:ffff
16825a0:a70::/2825a0:a7f:ffff:ffff:ffff:ffff:ffff:ffff
16925a0:a80::/2825a0:a8f:ffff:ffff:ffff:ffff:ffff:ffff
17025a0:a90::/2825a0:a9f:ffff:ffff:ffff:ffff:ffff:ffff
17125a0:aa0::/2825a0:aaf:ffff:ffff:ffff:ffff:ffff:ffff
17225a0:ab0::/2825a0:abf:ffff:ffff:ffff:ffff:ffff:ffff
17325a0:ac0::/2825a0:acf:ffff:ffff:ffff:ffff:ffff:ffff
17425a0:ad0::/2825a0:adf:ffff:ffff:ffff:ffff:ffff:ffff
17525a0:ae0::/2825a0:aef:ffff:ffff:ffff:ffff:ffff:ffff
17625a0:af0::/2825a0:aff:ffff:ffff:ffff:ffff:ffff:ffff
17725a0:b00::/2825a0:b0f:ffff:ffff:ffff:ffff:ffff:ffff
17825a0:b10::/2825a0:b1f:ffff:ffff:ffff:ffff:ffff:ffff
17925a0:b20::/2825a0:b2f:ffff:ffff:ffff:ffff:ffff:ffff
18025a0:b30::/2825a0:b3f:ffff:ffff:ffff:ffff:ffff:ffff
18125a0:b40::/2825a0:b4f:ffff:ffff:ffff:ffff:ffff:ffff
18225a0:b50::/2825a0:b5f:ffff:ffff:ffff:ffff:ffff:ffff
18325a0:b60::/2825a0:b6f:ffff:ffff:ffff:ffff:ffff:ffff
18425a0:b70::/2825a0:b7f:ffff:ffff:ffff:ffff:ffff:ffff
18525a0:b80::/2825a0:b8f:ffff:ffff:ffff:ffff:ffff:ffff
18625a0:b90::/2825a0:b9f:ffff:ffff:ffff:ffff:ffff:ffff
18725a0:ba0::/2825a0:baf:ffff:ffff:ffff:ffff:ffff:ffff
18825a0:bb0::/2825a0:bbf:ffff:ffff:ffff:ffff:ffff:ffff
18925a0:bc0::/2825a0:bcf:ffff:ffff:ffff:ffff:ffff:ffff
19025a0:bd0::/2825a0:bdf:ffff:ffff:ffff:ffff:ffff:ffff
19125a0:be0::/2825a0:bef:ffff:ffff:ffff:ffff:ffff:ffff
19225a0:bf0::/2825a0:bff:ffff:ffff:ffff:ffff:ffff:ffff
19325a0:c00::/2825a0:c0f:ffff:ffff:ffff:ffff:ffff:ffff
19425a0:c10::/2825a0:c1f:ffff:ffff:ffff:ffff:ffff:ffff
19525a0:c20::/2825a0:c2f:ffff:ffff:ffff:ffff:ffff:ffff
19625a0:c30::/2825a0:c3f:ffff:ffff:ffff:ffff:ffff:ffff
19725a0:c40::/2825a0:c4f:ffff:ffff:ffff:ffff:ffff:ffff
19825a0:c50::/2825a0:c5f:ffff:ffff:ffff:ffff:ffff:ffff
19925a0:c60::/2825a0:c6f:ffff:ffff:ffff:ffff:ffff:ffff
20025a0:c70::/2825a0:c7f:ffff:ffff:ffff:ffff:ffff:ffff
20125a0:c80::/2825a0:c8f:ffff:ffff:ffff:ffff:ffff:ffff
20225a0:c90::/2825a0:c9f:ffff:ffff:ffff:ffff:ffff:ffff
20325a0:ca0::/2825a0:caf:ffff:ffff:ffff:ffff:ffff:ffff
20425a0:cb0::/2825a0:cbf:ffff:ffff:ffff:ffff:ffff:ffff
20525a0:cc0::/2825a0:ccf:ffff:ffff:ffff:ffff:ffff:ffff
20625a0:cd0::/2825a0:cdf:ffff:ffff:ffff:ffff:ffff:ffff
20725a0:ce0::/2825a0:cef:ffff:ffff:ffff:ffff:ffff:ffff
20825a0:cf0::/2825a0:cff:ffff:ffff:ffff:ffff:ffff:ffff
20925a0:d00::/2825a0:d0f:ffff:ffff:ffff:ffff:ffff:ffff
21025a0:d10::/2825a0:d1f:ffff:ffff:ffff:ffff:ffff:ffff
21125a0:d20::/2825a0:d2f:ffff:ffff:ffff:ffff:ffff:ffff
21225a0:d30::/2825a0:d3f:ffff:ffff:ffff:ffff:ffff:ffff
21325a0:d40::/2825a0:d4f:ffff:ffff:ffff:ffff:ffff:ffff
21425a0:d50::/2825a0:d5f:ffff:ffff:ffff:ffff:ffff:ffff
21525a0:d60::/2825a0:d6f:ffff:ffff:ffff:ffff:ffff:ffff
21625a0:d70::/2825a0:d7f:ffff:ffff:ffff:ffff:ffff:ffff
21725a0:d80::/2825a0:d8f:ffff:ffff:ffff:ffff:ffff:ffff
21825a0:d90::/2825a0:d9f:ffff:ffff:ffff:ffff:ffff:ffff
21925a0:da0::/2825a0:daf:ffff:ffff:ffff:ffff:ffff:ffff
22025a0:db0::/2825a0:dbf:ffff:ffff:ffff:ffff:ffff:ffff
22125a0:dc0::/2825a0:dcf:ffff:ffff:ffff:ffff:ffff:ffff
22225a0:dd0::/2825a0:ddf:ffff:ffff:ffff:ffff:ffff:ffff
22325a0:de0::/2825a0:def:ffff:ffff:ffff:ffff:ffff:ffff
22425a0:df0::/2825a0:dff:ffff:ffff:ffff:ffff:ffff:ffff
22525a0:e00::/2825a0:e0f:ffff:ffff:ffff:ffff:ffff:ffff
22625a0:e10::/2825a0:e1f:ffff:ffff:ffff:ffff:ffff:ffff
22725a0:e20::/2825a0:e2f:ffff:ffff:ffff:ffff:ffff:ffff
22825a0:e30::/2825a0:e3f:ffff:ffff:ffff:ffff:ffff:ffff
22925a0:e40::/2825a0:e4f:ffff:ffff:ffff:ffff:ffff:ffff
23025a0:e50::/2825a0:e5f:ffff:ffff:ffff:ffff:ffff:ffff
23125a0:e60::/2825a0:e6f:ffff:ffff:ffff:ffff:ffff:ffff
23225a0:e70::/2825a0:e7f:ffff:ffff:ffff:ffff:ffff:ffff
23325a0:e80::/2825a0:e8f:ffff:ffff:ffff:ffff:ffff:ffff
23425a0:e90::/2825a0:e9f:ffff:ffff:ffff:ffff:ffff:ffff
23525a0:ea0::/2825a0:eaf:ffff:ffff:ffff:ffff:ffff:ffff
23625a0:eb0::/2825a0:ebf:ffff:ffff:ffff:ffff:ffff:ffff
23725a0:ec0::/2825a0:ecf:ffff:ffff:ffff:ffff:ffff:ffff
23825a0:ed0::/2825a0:edf:ffff:ffff:ffff:ffff:ffff:ffff
23925a0:ee0::/2825a0:eef:ffff:ffff:ffff:ffff:ffff:ffff
24025a0:ef0::/2825a0:eff:ffff:ffff:ffff:ffff:ffff:ffff
24125a0:f00::/2825a0:f0f:ffff:ffff:ffff:ffff:ffff:ffff
24225a0:f10::/2825a0:f1f:ffff:ffff:ffff:ffff:ffff:ffff
24325a0:f20::/2825a0:f2f:ffff:ffff:ffff:ffff:ffff:ffff
24425a0:f30::/2825a0:f3f:ffff:ffff:ffff:ffff:ffff:ffff
24525a0:f40::/2825a0:f4f:ffff:ffff:ffff:ffff:ffff:ffff
24625a0:f50::/2825a0:f5f:ffff:ffff:ffff:ffff:ffff:ffff
24725a0:f60::/2825a0:f6f:ffff:ffff:ffff:ffff:ffff:ffff
24825a0:f70::/2825a0:f7f:ffff:ffff:ffff:ffff:ffff:ffff
24925a0:f80::/2825a0:f8f:ffff:ffff:ffff:ffff:ffff:ffff
25025a0:f90::/2825a0:f9f:ffff:ffff:ffff:ffff:ffff:ffff
25125a0:fa0::/2825a0:faf:ffff:ffff:ffff:ffff:ffff:ffff
25225a0:fb0::/2825a0:fbf:ffff:ffff:ffff:ffff:ffff:ffff
25325a0:fc0::/2825a0:fcf:ffff:ffff:ffff:ffff:ffff:ffff
25425a0:fd0::/2825a0:fdf:ffff:ffff:ffff:ffff:ffff:ffff
25525a0:fe0::/2825a0:fef:ffff:ffff:ffff:ffff:ffff:ffff
25625a0:ff0::/2825a0:fff: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.