Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

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.

Computers and devices

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.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

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/16
Addresses2^112
/64 networks2^48
Network
2e1a::/16
First address
2e1a::
Last address
2e1a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
2e1a:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
a.1.e.2.ip6.arpa
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

2e1a::/16 makes 4,096 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
12e1a::/282e1a:f:ffff:ffff:ffff:ffff:ffff:ffff
22e1a:10::/282e1a:1f:ffff:ffff:ffff:ffff:ffff:ffff
32e1a:20::/282e1a:2f:ffff:ffff:ffff:ffff:ffff:ffff
42e1a:30::/282e1a:3f:ffff:ffff:ffff:ffff:ffff:ffff
52e1a:40::/282e1a:4f:ffff:ffff:ffff:ffff:ffff:ffff
62e1a:50::/282e1a:5f:ffff:ffff:ffff:ffff:ffff:ffff
72e1a:60::/282e1a:6f:ffff:ffff:ffff:ffff:ffff:ffff
82e1a:70::/282e1a:7f:ffff:ffff:ffff:ffff:ffff:ffff
92e1a:80::/282e1a:8f:ffff:ffff:ffff:ffff:ffff:ffff
102e1a:90::/282e1a:9f:ffff:ffff:ffff:ffff:ffff:ffff
112e1a:a0::/282e1a:af:ffff:ffff:ffff:ffff:ffff:ffff
122e1a:b0::/282e1a:bf:ffff:ffff:ffff:ffff:ffff:ffff
132e1a:c0::/282e1a:cf:ffff:ffff:ffff:ffff:ffff:ffff
142e1a:d0::/282e1a:df:ffff:ffff:ffff:ffff:ffff:ffff
152e1a:e0::/282e1a:ef:ffff:ffff:ffff:ffff:ffff:ffff
162e1a:f0::/282e1a:ff:ffff:ffff:ffff:ffff:ffff:ffff
172e1a:100::/282e1a:10f:ffff:ffff:ffff:ffff:ffff:ffff
182e1a:110::/282e1a:11f:ffff:ffff:ffff:ffff:ffff:ffff
192e1a:120::/282e1a:12f:ffff:ffff:ffff:ffff:ffff:ffff
202e1a:130::/282e1a:13f:ffff:ffff:ffff:ffff:ffff:ffff
212e1a:140::/282e1a:14f:ffff:ffff:ffff:ffff:ffff:ffff
222e1a:150::/282e1a:15f:ffff:ffff:ffff:ffff:ffff:ffff
232e1a:160::/282e1a:16f:ffff:ffff:ffff:ffff:ffff:ffff
242e1a:170::/282e1a:17f:ffff:ffff:ffff:ffff:ffff:ffff
252e1a:180::/282e1a:18f:ffff:ffff:ffff:ffff:ffff:ffff
262e1a:190::/282e1a:19f:ffff:ffff:ffff:ffff:ffff:ffff
272e1a:1a0::/282e1a:1af:ffff:ffff:ffff:ffff:ffff:ffff
282e1a:1b0::/282e1a:1bf:ffff:ffff:ffff:ffff:ffff:ffff
292e1a:1c0::/282e1a:1cf:ffff:ffff:ffff:ffff:ffff:ffff
302e1a:1d0::/282e1a:1df:ffff:ffff:ffff:ffff:ffff:ffff
312e1a:1e0::/282e1a:1ef:ffff:ffff:ffff:ffff:ffff:ffff
322e1a:1f0::/282e1a:1ff:ffff:ffff:ffff:ffff:ffff:ffff
332e1a:200::/282e1a:20f:ffff:ffff:ffff:ffff:ffff:ffff
342e1a:210::/282e1a:21f:ffff:ffff:ffff:ffff:ffff:ffff
352e1a:220::/282e1a:22f:ffff:ffff:ffff:ffff:ffff:ffff
362e1a:230::/282e1a:23f:ffff:ffff:ffff:ffff:ffff:ffff
372e1a:240::/282e1a:24f:ffff:ffff:ffff:ffff:ffff:ffff
382e1a:250::/282e1a:25f:ffff:ffff:ffff:ffff:ffff:ffff
392e1a:260::/282e1a:26f:ffff:ffff:ffff:ffff:ffff:ffff
402e1a:270::/282e1a:27f:ffff:ffff:ffff:ffff:ffff:ffff
412e1a:280::/282e1a:28f:ffff:ffff:ffff:ffff:ffff:ffff
422e1a:290::/282e1a:29f:ffff:ffff:ffff:ffff:ffff:ffff
432e1a:2a0::/282e1a:2af:ffff:ffff:ffff:ffff:ffff:ffff
442e1a:2b0::/282e1a:2bf:ffff:ffff:ffff:ffff:ffff:ffff
452e1a:2c0::/282e1a:2cf:ffff:ffff:ffff:ffff:ffff:ffff
462e1a:2d0::/282e1a:2df:ffff:ffff:ffff:ffff:ffff:ffff
472e1a:2e0::/282e1a:2ef:ffff:ffff:ffff:ffff:ffff:ffff
482e1a:2f0::/282e1a:2ff:ffff:ffff:ffff:ffff:ffff:ffff
492e1a:300::/282e1a:30f:ffff:ffff:ffff:ffff:ffff:ffff
502e1a:310::/282e1a:31f:ffff:ffff:ffff:ffff:ffff:ffff
512e1a:320::/282e1a:32f:ffff:ffff:ffff:ffff:ffff:ffff
522e1a:330::/282e1a:33f:ffff:ffff:ffff:ffff:ffff:ffff
532e1a:340::/282e1a:34f:ffff:ffff:ffff:ffff:ffff:ffff
542e1a:350::/282e1a:35f:ffff:ffff:ffff:ffff:ffff:ffff
552e1a:360::/282e1a:36f:ffff:ffff:ffff:ffff:ffff:ffff
562e1a:370::/282e1a:37f:ffff:ffff:ffff:ffff:ffff:ffff
572e1a:380::/282e1a:38f:ffff:ffff:ffff:ffff:ffff:ffff
582e1a:390::/282e1a:39f:ffff:ffff:ffff:ffff:ffff:ffff
592e1a:3a0::/282e1a:3af:ffff:ffff:ffff:ffff:ffff:ffff
602e1a:3b0::/282e1a:3bf:ffff:ffff:ffff:ffff:ffff:ffff
612e1a:3c0::/282e1a:3cf:ffff:ffff:ffff:ffff:ffff:ffff
622e1a:3d0::/282e1a:3df:ffff:ffff:ffff:ffff:ffff:ffff
632e1a:3e0::/282e1a:3ef:ffff:ffff:ffff:ffff:ffff:ffff
642e1a:3f0::/282e1a:3ff:ffff:ffff:ffff:ffff:ffff:ffff
652e1a:400::/282e1a:40f:ffff:ffff:ffff:ffff:ffff:ffff
662e1a:410::/282e1a:41f:ffff:ffff:ffff:ffff:ffff:ffff
672e1a:420::/282e1a:42f:ffff:ffff:ffff:ffff:ffff:ffff
682e1a:430::/282e1a:43f:ffff:ffff:ffff:ffff:ffff:ffff
692e1a:440::/282e1a:44f:ffff:ffff:ffff:ffff:ffff:ffff
702e1a:450::/282e1a:45f:ffff:ffff:ffff:ffff:ffff:ffff
712e1a:460::/282e1a:46f:ffff:ffff:ffff:ffff:ffff:ffff
722e1a:470::/282e1a:47f:ffff:ffff:ffff:ffff:ffff:ffff
732e1a:480::/282e1a:48f:ffff:ffff:ffff:ffff:ffff:ffff
742e1a:490::/282e1a:49f:ffff:ffff:ffff:ffff:ffff:ffff
752e1a:4a0::/282e1a:4af:ffff:ffff:ffff:ffff:ffff:ffff
762e1a:4b0::/282e1a:4bf:ffff:ffff:ffff:ffff:ffff:ffff
772e1a:4c0::/282e1a:4cf:ffff:ffff:ffff:ffff:ffff:ffff
782e1a:4d0::/282e1a:4df:ffff:ffff:ffff:ffff:ffff:ffff
792e1a:4e0::/282e1a:4ef:ffff:ffff:ffff:ffff:ffff:ffff
802e1a:4f0::/282e1a:4ff:ffff:ffff:ffff:ffff:ffff:ffff
812e1a:500::/282e1a:50f:ffff:ffff:ffff:ffff:ffff:ffff
822e1a:510::/282e1a:51f:ffff:ffff:ffff:ffff:ffff:ffff
832e1a:520::/282e1a:52f:ffff:ffff:ffff:ffff:ffff:ffff
842e1a:530::/282e1a:53f:ffff:ffff:ffff:ffff:ffff:ffff
852e1a:540::/282e1a:54f:ffff:ffff:ffff:ffff:ffff:ffff
862e1a:550::/282e1a:55f:ffff:ffff:ffff:ffff:ffff:ffff
872e1a:560::/282e1a:56f:ffff:ffff:ffff:ffff:ffff:ffff
882e1a:570::/282e1a:57f:ffff:ffff:ffff:ffff:ffff:ffff
892e1a:580::/282e1a:58f:ffff:ffff:ffff:ffff:ffff:ffff
902e1a:590::/282e1a:59f:ffff:ffff:ffff:ffff:ffff:ffff
912e1a:5a0::/282e1a:5af:ffff:ffff:ffff:ffff:ffff:ffff
922e1a:5b0::/282e1a:5bf:ffff:ffff:ffff:ffff:ffff:ffff
932e1a:5c0::/282e1a:5cf:ffff:ffff:ffff:ffff:ffff:ffff
942e1a:5d0::/282e1a:5df:ffff:ffff:ffff:ffff:ffff:ffff
952e1a:5e0::/282e1a:5ef:ffff:ffff:ffff:ffff:ffff:ffff
962e1a:5f0::/282e1a:5ff:ffff:ffff:ffff:ffff:ffff:ffff
972e1a:600::/282e1a:60f:ffff:ffff:ffff:ffff:ffff:ffff
982e1a:610::/282e1a:61f:ffff:ffff:ffff:ffff:ffff:ffff
992e1a:620::/282e1a:62f:ffff:ffff:ffff:ffff:ffff:ffff
1002e1a:630::/282e1a:63f:ffff:ffff:ffff:ffff:ffff:ffff
1012e1a:640::/282e1a:64f:ffff:ffff:ffff:ffff:ffff:ffff
1022e1a:650::/282e1a:65f:ffff:ffff:ffff:ffff:ffff:ffff
1032e1a:660::/282e1a:66f:ffff:ffff:ffff:ffff:ffff:ffff
1042e1a:670::/282e1a:67f:ffff:ffff:ffff:ffff:ffff:ffff
1052e1a:680::/282e1a:68f:ffff:ffff:ffff:ffff:ffff:ffff
1062e1a:690::/282e1a:69f:ffff:ffff:ffff:ffff:ffff:ffff
1072e1a:6a0::/282e1a:6af:ffff:ffff:ffff:ffff:ffff:ffff
1082e1a:6b0::/282e1a:6bf:ffff:ffff:ffff:ffff:ffff:ffff
1092e1a:6c0::/282e1a:6cf:ffff:ffff:ffff:ffff:ffff:ffff
1102e1a:6d0::/282e1a:6df:ffff:ffff:ffff:ffff:ffff:ffff
1112e1a:6e0::/282e1a:6ef:ffff:ffff:ffff:ffff:ffff:ffff
1122e1a:6f0::/282e1a:6ff:ffff:ffff:ffff:ffff:ffff:ffff
1132e1a:700::/282e1a:70f:ffff:ffff:ffff:ffff:ffff:ffff
1142e1a:710::/282e1a:71f:ffff:ffff:ffff:ffff:ffff:ffff
1152e1a:720::/282e1a:72f:ffff:ffff:ffff:ffff:ffff:ffff
1162e1a:730::/282e1a:73f:ffff:ffff:ffff:ffff:ffff:ffff
1172e1a:740::/282e1a:74f:ffff:ffff:ffff:ffff:ffff:ffff
1182e1a:750::/282e1a:75f:ffff:ffff:ffff:ffff:ffff:ffff
1192e1a:760::/282e1a:76f:ffff:ffff:ffff:ffff:ffff:ffff
1202e1a:770::/282e1a:77f:ffff:ffff:ffff:ffff:ffff:ffff
1212e1a:780::/282e1a:78f:ffff:ffff:ffff:ffff:ffff:ffff
1222e1a:790::/282e1a:79f:ffff:ffff:ffff:ffff:ffff:ffff
1232e1a:7a0::/282e1a:7af:ffff:ffff:ffff:ffff:ffff:ffff
1242e1a:7b0::/282e1a:7bf:ffff:ffff:ffff:ffff:ffff:ffff
1252e1a:7c0::/282e1a:7cf:ffff:ffff:ffff:ffff:ffff:ffff
1262e1a:7d0::/282e1a:7df:ffff:ffff:ffff:ffff:ffff:ffff
1272e1a:7e0::/282e1a:7ef:ffff:ffff:ffff:ffff:ffff:ffff
1282e1a:7f0::/282e1a:7ff:ffff:ffff:ffff:ffff:ffff:ffff
1292e1a:800::/282e1a:80f:ffff:ffff:ffff:ffff:ffff:ffff
1302e1a:810::/282e1a:81f:ffff:ffff:ffff:ffff:ffff:ffff
1312e1a:820::/282e1a:82f:ffff:ffff:ffff:ffff:ffff:ffff
1322e1a:830::/282e1a:83f:ffff:ffff:ffff:ffff:ffff:ffff
1332e1a:840::/282e1a:84f:ffff:ffff:ffff:ffff:ffff:ffff
1342e1a:850::/282e1a:85f:ffff:ffff:ffff:ffff:ffff:ffff
1352e1a:860::/282e1a:86f:ffff:ffff:ffff:ffff:ffff:ffff
1362e1a:870::/282e1a:87f:ffff:ffff:ffff:ffff:ffff:ffff
1372e1a:880::/282e1a:88f:ffff:ffff:ffff:ffff:ffff:ffff
1382e1a:890::/282e1a:89f:ffff:ffff:ffff:ffff:ffff:ffff
1392e1a:8a0::/282e1a:8af:ffff:ffff:ffff:ffff:ffff:ffff
1402e1a:8b0::/282e1a:8bf:ffff:ffff:ffff:ffff:ffff:ffff
1412e1a:8c0::/282e1a:8cf:ffff:ffff:ffff:ffff:ffff:ffff
1422e1a:8d0::/282e1a:8df:ffff:ffff:ffff:ffff:ffff:ffff
1432e1a:8e0::/282e1a:8ef:ffff:ffff:ffff:ffff:ffff:ffff
1442e1a:8f0::/282e1a:8ff:ffff:ffff:ffff:ffff:ffff:ffff
1452e1a:900::/282e1a:90f:ffff:ffff:ffff:ffff:ffff:ffff
1462e1a:910::/282e1a:91f:ffff:ffff:ffff:ffff:ffff:ffff
1472e1a:920::/282e1a:92f:ffff:ffff:ffff:ffff:ffff:ffff
1482e1a:930::/282e1a:93f:ffff:ffff:ffff:ffff:ffff:ffff
1492e1a:940::/282e1a:94f:ffff:ffff:ffff:ffff:ffff:ffff
1502e1a:950::/282e1a:95f:ffff:ffff:ffff:ffff:ffff:ffff
1512e1a:960::/282e1a:96f:ffff:ffff:ffff:ffff:ffff:ffff
1522e1a:970::/282e1a:97f:ffff:ffff:ffff:ffff:ffff:ffff
1532e1a:980::/282e1a:98f:ffff:ffff:ffff:ffff:ffff:ffff
1542e1a:990::/282e1a:99f:ffff:ffff:ffff:ffff:ffff:ffff
1552e1a:9a0::/282e1a:9af:ffff:ffff:ffff:ffff:ffff:ffff
1562e1a:9b0::/282e1a:9bf:ffff:ffff:ffff:ffff:ffff:ffff
1572e1a:9c0::/282e1a:9cf:ffff:ffff:ffff:ffff:ffff:ffff
1582e1a:9d0::/282e1a:9df:ffff:ffff:ffff:ffff:ffff:ffff
1592e1a:9e0::/282e1a:9ef:ffff:ffff:ffff:ffff:ffff:ffff
1602e1a:9f0::/282e1a:9ff:ffff:ffff:ffff:ffff:ffff:ffff
1612e1a:a00::/282e1a:a0f:ffff:ffff:ffff:ffff:ffff:ffff
1622e1a:a10::/282e1a:a1f:ffff:ffff:ffff:ffff:ffff:ffff
1632e1a:a20::/282e1a:a2f:ffff:ffff:ffff:ffff:ffff:ffff
1642e1a:a30::/282e1a:a3f:ffff:ffff:ffff:ffff:ffff:ffff
1652e1a:a40::/282e1a:a4f:ffff:ffff:ffff:ffff:ffff:ffff
1662e1a:a50::/282e1a:a5f:ffff:ffff:ffff:ffff:ffff:ffff
1672e1a:a60::/282e1a:a6f:ffff:ffff:ffff:ffff:ffff:ffff
1682e1a:a70::/282e1a:a7f:ffff:ffff:ffff:ffff:ffff:ffff
1692e1a:a80::/282e1a:a8f:ffff:ffff:ffff:ffff:ffff:ffff
1702e1a:a90::/282e1a:a9f:ffff:ffff:ffff:ffff:ffff:ffff
1712e1a:aa0::/282e1a:aaf:ffff:ffff:ffff:ffff:ffff:ffff
1722e1a:ab0::/282e1a:abf:ffff:ffff:ffff:ffff:ffff:ffff
1732e1a:ac0::/282e1a:acf:ffff:ffff:ffff:ffff:ffff:ffff
1742e1a:ad0::/282e1a:adf:ffff:ffff:ffff:ffff:ffff:ffff
1752e1a:ae0::/282e1a:aef:ffff:ffff:ffff:ffff:ffff:ffff
1762e1a:af0::/282e1a:aff:ffff:ffff:ffff:ffff:ffff:ffff
1772e1a:b00::/282e1a:b0f:ffff:ffff:ffff:ffff:ffff:ffff
1782e1a:b10::/282e1a:b1f:ffff:ffff:ffff:ffff:ffff:ffff
1792e1a:b20::/282e1a:b2f:ffff:ffff:ffff:ffff:ffff:ffff
1802e1a:b30::/282e1a:b3f:ffff:ffff:ffff:ffff:ffff:ffff
1812e1a:b40::/282e1a:b4f:ffff:ffff:ffff:ffff:ffff:ffff
1822e1a:b50::/282e1a:b5f:ffff:ffff:ffff:ffff:ffff:ffff
1832e1a:b60::/282e1a:b6f:ffff:ffff:ffff:ffff:ffff:ffff
1842e1a:b70::/282e1a:b7f:ffff:ffff:ffff:ffff:ffff:ffff
1852e1a:b80::/282e1a:b8f:ffff:ffff:ffff:ffff:ffff:ffff
1862e1a:b90::/282e1a:b9f:ffff:ffff:ffff:ffff:ffff:ffff
1872e1a:ba0::/282e1a:baf:ffff:ffff:ffff:ffff:ffff:ffff
1882e1a:bb0::/282e1a:bbf:ffff:ffff:ffff:ffff:ffff:ffff
1892e1a:bc0::/282e1a:bcf:ffff:ffff:ffff:ffff:ffff:ffff
1902e1a:bd0::/282e1a:bdf:ffff:ffff:ffff:ffff:ffff:ffff
1912e1a:be0::/282e1a:bef:ffff:ffff:ffff:ffff:ffff:ffff
1922e1a:bf0::/282e1a:bff:ffff:ffff:ffff:ffff:ffff:ffff
1932e1a:c00::/282e1a:c0f:ffff:ffff:ffff:ffff:ffff:ffff
1942e1a:c10::/282e1a:c1f:ffff:ffff:ffff:ffff:ffff:ffff
1952e1a:c20::/282e1a:c2f:ffff:ffff:ffff:ffff:ffff:ffff
1962e1a:c30::/282e1a:c3f:ffff:ffff:ffff:ffff:ffff:ffff
1972e1a:c40::/282e1a:c4f:ffff:ffff:ffff:ffff:ffff:ffff
1982e1a:c50::/282e1a:c5f:ffff:ffff:ffff:ffff:ffff:ffff
1992e1a:c60::/282e1a:c6f:ffff:ffff:ffff:ffff:ffff:ffff
2002e1a:c70::/282e1a:c7f:ffff:ffff:ffff:ffff:ffff:ffff
2012e1a:c80::/282e1a:c8f:ffff:ffff:ffff:ffff:ffff:ffff
2022e1a:c90::/282e1a:c9f:ffff:ffff:ffff:ffff:ffff:ffff
2032e1a:ca0::/282e1a:caf:ffff:ffff:ffff:ffff:ffff:ffff
2042e1a:cb0::/282e1a:cbf:ffff:ffff:ffff:ffff:ffff:ffff
2052e1a:cc0::/282e1a:ccf:ffff:ffff:ffff:ffff:ffff:ffff
2062e1a:cd0::/282e1a:cdf:ffff:ffff:ffff:ffff:ffff:ffff
2072e1a:ce0::/282e1a:cef:ffff:ffff:ffff:ffff:ffff:ffff
2082e1a:cf0::/282e1a:cff:ffff:ffff:ffff:ffff:ffff:ffff
2092e1a:d00::/282e1a:d0f:ffff:ffff:ffff:ffff:ffff:ffff
2102e1a:d10::/282e1a:d1f:ffff:ffff:ffff:ffff:ffff:ffff
2112e1a:d20::/282e1a:d2f:ffff:ffff:ffff:ffff:ffff:ffff
2122e1a:d30::/282e1a:d3f:ffff:ffff:ffff:ffff:ffff:ffff
2132e1a:d40::/282e1a:d4f:ffff:ffff:ffff:ffff:ffff:ffff
2142e1a:d50::/282e1a:d5f:ffff:ffff:ffff:ffff:ffff:ffff
2152e1a:d60::/282e1a:d6f:ffff:ffff:ffff:ffff:ffff:ffff
2162e1a:d70::/282e1a:d7f:ffff:ffff:ffff:ffff:ffff:ffff
2172e1a:d80::/282e1a:d8f:ffff:ffff:ffff:ffff:ffff:ffff
2182e1a:d90::/282e1a:d9f:ffff:ffff:ffff:ffff:ffff:ffff
2192e1a:da0::/282e1a:daf:ffff:ffff:ffff:ffff:ffff:ffff
2202e1a:db0::/282e1a:dbf:ffff:ffff:ffff:ffff:ffff:ffff
2212e1a:dc0::/282e1a:dcf:ffff:ffff:ffff:ffff:ffff:ffff
2222e1a:dd0::/282e1a:ddf:ffff:ffff:ffff:ffff:ffff:ffff
2232e1a:de0::/282e1a:def:ffff:ffff:ffff:ffff:ffff:ffff
2242e1a:df0::/282e1a:dff:ffff:ffff:ffff:ffff:ffff:ffff
2252e1a:e00::/282e1a:e0f:ffff:ffff:ffff:ffff:ffff:ffff
2262e1a:e10::/282e1a:e1f:ffff:ffff:ffff:ffff:ffff:ffff
2272e1a:e20::/282e1a:e2f:ffff:ffff:ffff:ffff:ffff:ffff
2282e1a:e30::/282e1a:e3f:ffff:ffff:ffff:ffff:ffff:ffff
2292e1a:e40::/282e1a:e4f:ffff:ffff:ffff:ffff:ffff:ffff
2302e1a:e50::/282e1a:e5f:ffff:ffff:ffff:ffff:ffff:ffff
2312e1a:e60::/282e1a:e6f:ffff:ffff:ffff:ffff:ffff:ffff
2322e1a:e70::/282e1a:e7f:ffff:ffff:ffff:ffff:ffff:ffff
2332e1a:e80::/282e1a:e8f:ffff:ffff:ffff:ffff:ffff:ffff
2342e1a:e90::/282e1a:e9f:ffff:ffff:ffff:ffff:ffff:ffff
2352e1a:ea0::/282e1a:eaf:ffff:ffff:ffff:ffff:ffff:ffff
2362e1a:eb0::/282e1a:ebf:ffff:ffff:ffff:ffff:ffff:ffff
2372e1a:ec0::/282e1a:ecf:ffff:ffff:ffff:ffff:ffff:ffff
2382e1a:ed0::/282e1a:edf:ffff:ffff:ffff:ffff:ffff:ffff
2392e1a:ee0::/282e1a:eef:ffff:ffff:ffff:ffff:ffff:ffff
2402e1a:ef0::/282e1a:eff:ffff:ffff:ffff:ffff:ffff:ffff
2412e1a:f00::/282e1a:f0f:ffff:ffff:ffff:ffff:ffff:ffff
2422e1a:f10::/282e1a:f1f:ffff:ffff:ffff:ffff:ffff:ffff
2432e1a:f20::/282e1a:f2f:ffff:ffff:ffff:ffff:ffff:ffff
2442e1a:f30::/282e1a:f3f:ffff:ffff:ffff:ffff:ffff:ffff
2452e1a:f40::/282e1a:f4f:ffff:ffff:ffff:ffff:ffff:ffff
2462e1a:f50::/282e1a:f5f:ffff:ffff:ffff:ffff:ffff:ffff
2472e1a:f60::/282e1a:f6f:ffff:ffff:ffff:ffff:ffff:ffff
2482e1a:f70::/282e1a:f7f:ffff:ffff:ffff:ffff:ffff:ffff
2492e1a:f80::/282e1a:f8f:ffff:ffff:ffff:ffff:ffff:ffff
2502e1a:f90::/282e1a:f9f:ffff:ffff:ffff:ffff:ffff:ffff
2512e1a:fa0::/282e1a:faf:ffff:ffff:ffff:ffff:ffff:ffff
2522e1a:fb0::/282e1a:fbf:ffff:ffff:ffff:ffff:ffff:ffff
2532e1a:fc0::/282e1a:fcf:ffff:ffff:ffff:ffff:ffff:ffff
2542e1a:fd0::/282e1a:fdf:ffff:ffff:ffff:ffff:ffff:ffff
2552e1a:fe0::/282e1a:fef:ffff:ffff:ffff:ffff:ffff:ffff
2562e1a:ff0::/282e1a: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.