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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
25b0::/12
First address
25b0::
Last address
25bf: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
25b0:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
b.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)

25b0::/12 makes 65,536 subnets of /28; the first 256 are listed.

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