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
2aec::/16
First address
2aec::
Last address
2aec: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
2aec:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
c.e.a.2.ip6.arpa
Split into smaller subnets/32
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

2aec::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
12aec::/322aec:0:ffff:ffff:ffff:ffff:ffff:ffff
22aec:1::/322aec:1:ffff:ffff:ffff:ffff:ffff:ffff
32aec:2::/322aec:2:ffff:ffff:ffff:ffff:ffff:ffff
42aec:3::/322aec:3:ffff:ffff:ffff:ffff:ffff:ffff
52aec:4::/322aec:4:ffff:ffff:ffff:ffff:ffff:ffff
62aec:5::/322aec:5:ffff:ffff:ffff:ffff:ffff:ffff
72aec:6::/322aec:6:ffff:ffff:ffff:ffff:ffff:ffff
82aec:7::/322aec:7:ffff:ffff:ffff:ffff:ffff:ffff
92aec:8::/322aec:8:ffff:ffff:ffff:ffff:ffff:ffff
102aec:9::/322aec:9:ffff:ffff:ffff:ffff:ffff:ffff
112aec:a::/322aec:a:ffff:ffff:ffff:ffff:ffff:ffff
122aec:b::/322aec:b:ffff:ffff:ffff:ffff:ffff:ffff
132aec:c::/322aec:c:ffff:ffff:ffff:ffff:ffff:ffff
142aec:d::/322aec:d:ffff:ffff:ffff:ffff:ffff:ffff
152aec:e::/322aec:e:ffff:ffff:ffff:ffff:ffff:ffff
162aec:f::/322aec:f:ffff:ffff:ffff:ffff:ffff:ffff
172aec:10::/322aec:10:ffff:ffff:ffff:ffff:ffff:ffff
182aec:11::/322aec:11:ffff:ffff:ffff:ffff:ffff:ffff
192aec:12::/322aec:12:ffff:ffff:ffff:ffff:ffff:ffff
202aec:13::/322aec:13:ffff:ffff:ffff:ffff:ffff:ffff
212aec:14::/322aec:14:ffff:ffff:ffff:ffff:ffff:ffff
222aec:15::/322aec:15:ffff:ffff:ffff:ffff:ffff:ffff
232aec:16::/322aec:16:ffff:ffff:ffff:ffff:ffff:ffff
242aec:17::/322aec:17:ffff:ffff:ffff:ffff:ffff:ffff
252aec:18::/322aec:18:ffff:ffff:ffff:ffff:ffff:ffff
262aec:19::/322aec:19:ffff:ffff:ffff:ffff:ffff:ffff
272aec:1a::/322aec:1a:ffff:ffff:ffff:ffff:ffff:ffff
282aec:1b::/322aec:1b:ffff:ffff:ffff:ffff:ffff:ffff
292aec:1c::/322aec:1c:ffff:ffff:ffff:ffff:ffff:ffff
302aec:1d::/322aec:1d:ffff:ffff:ffff:ffff:ffff:ffff
312aec:1e::/322aec:1e:ffff:ffff:ffff:ffff:ffff:ffff
322aec:1f::/322aec:1f:ffff:ffff:ffff:ffff:ffff:ffff
332aec:20::/322aec:20:ffff:ffff:ffff:ffff:ffff:ffff
342aec:21::/322aec:21:ffff:ffff:ffff:ffff:ffff:ffff
352aec:22::/322aec:22:ffff:ffff:ffff:ffff:ffff:ffff
362aec:23::/322aec:23:ffff:ffff:ffff:ffff:ffff:ffff
372aec:24::/322aec:24:ffff:ffff:ffff:ffff:ffff:ffff
382aec:25::/322aec:25:ffff:ffff:ffff:ffff:ffff:ffff
392aec:26::/322aec:26:ffff:ffff:ffff:ffff:ffff:ffff
402aec:27::/322aec:27:ffff:ffff:ffff:ffff:ffff:ffff
412aec:28::/322aec:28:ffff:ffff:ffff:ffff:ffff:ffff
422aec:29::/322aec:29:ffff:ffff:ffff:ffff:ffff:ffff
432aec:2a::/322aec:2a:ffff:ffff:ffff:ffff:ffff:ffff
442aec:2b::/322aec:2b:ffff:ffff:ffff:ffff:ffff:ffff
452aec:2c::/322aec:2c:ffff:ffff:ffff:ffff:ffff:ffff
462aec:2d::/322aec:2d:ffff:ffff:ffff:ffff:ffff:ffff
472aec:2e::/322aec:2e:ffff:ffff:ffff:ffff:ffff:ffff
482aec:2f::/322aec:2f:ffff:ffff:ffff:ffff:ffff:ffff
492aec:30::/322aec:30:ffff:ffff:ffff:ffff:ffff:ffff
502aec:31::/322aec:31:ffff:ffff:ffff:ffff:ffff:ffff
512aec:32::/322aec:32:ffff:ffff:ffff:ffff:ffff:ffff
522aec:33::/322aec:33:ffff:ffff:ffff:ffff:ffff:ffff
532aec:34::/322aec:34:ffff:ffff:ffff:ffff:ffff:ffff
542aec:35::/322aec:35:ffff:ffff:ffff:ffff:ffff:ffff
552aec:36::/322aec:36:ffff:ffff:ffff:ffff:ffff:ffff
562aec:37::/322aec:37:ffff:ffff:ffff:ffff:ffff:ffff
572aec:38::/322aec:38:ffff:ffff:ffff:ffff:ffff:ffff
582aec:39::/322aec:39:ffff:ffff:ffff:ffff:ffff:ffff
592aec:3a::/322aec:3a:ffff:ffff:ffff:ffff:ffff:ffff
602aec:3b::/322aec:3b:ffff:ffff:ffff:ffff:ffff:ffff
612aec:3c::/322aec:3c:ffff:ffff:ffff:ffff:ffff:ffff
622aec:3d::/322aec:3d:ffff:ffff:ffff:ffff:ffff:ffff
632aec:3e::/322aec:3e:ffff:ffff:ffff:ffff:ffff:ffff
642aec:3f::/322aec:3f:ffff:ffff:ffff:ffff:ffff:ffff
652aec:40::/322aec:40:ffff:ffff:ffff:ffff:ffff:ffff
662aec:41::/322aec:41:ffff:ffff:ffff:ffff:ffff:ffff
672aec:42::/322aec:42:ffff:ffff:ffff:ffff:ffff:ffff
682aec:43::/322aec:43:ffff:ffff:ffff:ffff:ffff:ffff
692aec:44::/322aec:44:ffff:ffff:ffff:ffff:ffff:ffff
702aec:45::/322aec:45:ffff:ffff:ffff:ffff:ffff:ffff
712aec:46::/322aec:46:ffff:ffff:ffff:ffff:ffff:ffff
722aec:47::/322aec:47:ffff:ffff:ffff:ffff:ffff:ffff
732aec:48::/322aec:48:ffff:ffff:ffff:ffff:ffff:ffff
742aec:49::/322aec:49:ffff:ffff:ffff:ffff:ffff:ffff
752aec:4a::/322aec:4a:ffff:ffff:ffff:ffff:ffff:ffff
762aec:4b::/322aec:4b:ffff:ffff:ffff:ffff:ffff:ffff
772aec:4c::/322aec:4c:ffff:ffff:ffff:ffff:ffff:ffff
782aec:4d::/322aec:4d:ffff:ffff:ffff:ffff:ffff:ffff
792aec:4e::/322aec:4e:ffff:ffff:ffff:ffff:ffff:ffff
802aec:4f::/322aec:4f:ffff:ffff:ffff:ffff:ffff:ffff
812aec:50::/322aec:50:ffff:ffff:ffff:ffff:ffff:ffff
822aec:51::/322aec:51:ffff:ffff:ffff:ffff:ffff:ffff
832aec:52::/322aec:52:ffff:ffff:ffff:ffff:ffff:ffff
842aec:53::/322aec:53:ffff:ffff:ffff:ffff:ffff:ffff
852aec:54::/322aec:54:ffff:ffff:ffff:ffff:ffff:ffff
862aec:55::/322aec:55:ffff:ffff:ffff:ffff:ffff:ffff
872aec:56::/322aec:56:ffff:ffff:ffff:ffff:ffff:ffff
882aec:57::/322aec:57:ffff:ffff:ffff:ffff:ffff:ffff
892aec:58::/322aec:58:ffff:ffff:ffff:ffff:ffff:ffff
902aec:59::/322aec:59:ffff:ffff:ffff:ffff:ffff:ffff
912aec:5a::/322aec:5a:ffff:ffff:ffff:ffff:ffff:ffff
922aec:5b::/322aec:5b:ffff:ffff:ffff:ffff:ffff:ffff
932aec:5c::/322aec:5c:ffff:ffff:ffff:ffff:ffff:ffff
942aec:5d::/322aec:5d:ffff:ffff:ffff:ffff:ffff:ffff
952aec:5e::/322aec:5e:ffff:ffff:ffff:ffff:ffff:ffff
962aec:5f::/322aec:5f:ffff:ffff:ffff:ffff:ffff:ffff
972aec:60::/322aec:60:ffff:ffff:ffff:ffff:ffff:ffff
982aec:61::/322aec:61:ffff:ffff:ffff:ffff:ffff:ffff
992aec:62::/322aec:62:ffff:ffff:ffff:ffff:ffff:ffff
1002aec:63::/322aec:63:ffff:ffff:ffff:ffff:ffff:ffff
1012aec:64::/322aec:64:ffff:ffff:ffff:ffff:ffff:ffff
1022aec:65::/322aec:65:ffff:ffff:ffff:ffff:ffff:ffff
1032aec:66::/322aec:66:ffff:ffff:ffff:ffff:ffff:ffff
1042aec:67::/322aec:67:ffff:ffff:ffff:ffff:ffff:ffff
1052aec:68::/322aec:68:ffff:ffff:ffff:ffff:ffff:ffff
1062aec:69::/322aec:69:ffff:ffff:ffff:ffff:ffff:ffff
1072aec:6a::/322aec:6a:ffff:ffff:ffff:ffff:ffff:ffff
1082aec:6b::/322aec:6b:ffff:ffff:ffff:ffff:ffff:ffff
1092aec:6c::/322aec:6c:ffff:ffff:ffff:ffff:ffff:ffff
1102aec:6d::/322aec:6d:ffff:ffff:ffff:ffff:ffff:ffff
1112aec:6e::/322aec:6e:ffff:ffff:ffff:ffff:ffff:ffff
1122aec:6f::/322aec:6f:ffff:ffff:ffff:ffff:ffff:ffff
1132aec:70::/322aec:70:ffff:ffff:ffff:ffff:ffff:ffff
1142aec:71::/322aec:71:ffff:ffff:ffff:ffff:ffff:ffff
1152aec:72::/322aec:72:ffff:ffff:ffff:ffff:ffff:ffff
1162aec:73::/322aec:73:ffff:ffff:ffff:ffff:ffff:ffff
1172aec:74::/322aec:74:ffff:ffff:ffff:ffff:ffff:ffff
1182aec:75::/322aec:75:ffff:ffff:ffff:ffff:ffff:ffff
1192aec:76::/322aec:76:ffff:ffff:ffff:ffff:ffff:ffff
1202aec:77::/322aec:77:ffff:ffff:ffff:ffff:ffff:ffff
1212aec:78::/322aec:78:ffff:ffff:ffff:ffff:ffff:ffff
1222aec:79::/322aec:79:ffff:ffff:ffff:ffff:ffff:ffff
1232aec:7a::/322aec:7a:ffff:ffff:ffff:ffff:ffff:ffff
1242aec:7b::/322aec:7b:ffff:ffff:ffff:ffff:ffff:ffff
1252aec:7c::/322aec:7c:ffff:ffff:ffff:ffff:ffff:ffff
1262aec:7d::/322aec:7d:ffff:ffff:ffff:ffff:ffff:ffff
1272aec:7e::/322aec:7e:ffff:ffff:ffff:ffff:ffff:ffff
1282aec:7f::/322aec:7f:ffff:ffff:ffff:ffff:ffff:ffff
1292aec:80::/322aec:80:ffff:ffff:ffff:ffff:ffff:ffff
1302aec:81::/322aec:81:ffff:ffff:ffff:ffff:ffff:ffff
1312aec:82::/322aec:82:ffff:ffff:ffff:ffff:ffff:ffff
1322aec:83::/322aec:83:ffff:ffff:ffff:ffff:ffff:ffff
1332aec:84::/322aec:84:ffff:ffff:ffff:ffff:ffff:ffff
1342aec:85::/322aec:85:ffff:ffff:ffff:ffff:ffff:ffff
1352aec:86::/322aec:86:ffff:ffff:ffff:ffff:ffff:ffff
1362aec:87::/322aec:87:ffff:ffff:ffff:ffff:ffff:ffff
1372aec:88::/322aec:88:ffff:ffff:ffff:ffff:ffff:ffff
1382aec:89::/322aec:89:ffff:ffff:ffff:ffff:ffff:ffff
1392aec:8a::/322aec:8a:ffff:ffff:ffff:ffff:ffff:ffff
1402aec:8b::/322aec:8b:ffff:ffff:ffff:ffff:ffff:ffff
1412aec:8c::/322aec:8c:ffff:ffff:ffff:ffff:ffff:ffff
1422aec:8d::/322aec:8d:ffff:ffff:ffff:ffff:ffff:ffff
1432aec:8e::/322aec:8e:ffff:ffff:ffff:ffff:ffff:ffff
1442aec:8f::/322aec:8f:ffff:ffff:ffff:ffff:ffff:ffff
1452aec:90::/322aec:90:ffff:ffff:ffff:ffff:ffff:ffff
1462aec:91::/322aec:91:ffff:ffff:ffff:ffff:ffff:ffff
1472aec:92::/322aec:92:ffff:ffff:ffff:ffff:ffff:ffff
1482aec:93::/322aec:93:ffff:ffff:ffff:ffff:ffff:ffff
1492aec:94::/322aec:94:ffff:ffff:ffff:ffff:ffff:ffff
1502aec:95::/322aec:95:ffff:ffff:ffff:ffff:ffff:ffff
1512aec:96::/322aec:96:ffff:ffff:ffff:ffff:ffff:ffff
1522aec:97::/322aec:97:ffff:ffff:ffff:ffff:ffff:ffff
1532aec:98::/322aec:98:ffff:ffff:ffff:ffff:ffff:ffff
1542aec:99::/322aec:99:ffff:ffff:ffff:ffff:ffff:ffff
1552aec:9a::/322aec:9a:ffff:ffff:ffff:ffff:ffff:ffff
1562aec:9b::/322aec:9b:ffff:ffff:ffff:ffff:ffff:ffff
1572aec:9c::/322aec:9c:ffff:ffff:ffff:ffff:ffff:ffff
1582aec:9d::/322aec:9d:ffff:ffff:ffff:ffff:ffff:ffff
1592aec:9e::/322aec:9e:ffff:ffff:ffff:ffff:ffff:ffff
1602aec:9f::/322aec:9f:ffff:ffff:ffff:ffff:ffff:ffff
1612aec:a0::/322aec:a0:ffff:ffff:ffff:ffff:ffff:ffff
1622aec:a1::/322aec:a1:ffff:ffff:ffff:ffff:ffff:ffff
1632aec:a2::/322aec:a2:ffff:ffff:ffff:ffff:ffff:ffff
1642aec:a3::/322aec:a3:ffff:ffff:ffff:ffff:ffff:ffff
1652aec:a4::/322aec:a4:ffff:ffff:ffff:ffff:ffff:ffff
1662aec:a5::/322aec:a5:ffff:ffff:ffff:ffff:ffff:ffff
1672aec:a6::/322aec:a6:ffff:ffff:ffff:ffff:ffff:ffff
1682aec:a7::/322aec:a7:ffff:ffff:ffff:ffff:ffff:ffff
1692aec:a8::/322aec:a8:ffff:ffff:ffff:ffff:ffff:ffff
1702aec:a9::/322aec:a9:ffff:ffff:ffff:ffff:ffff:ffff
1712aec:aa::/322aec:aa:ffff:ffff:ffff:ffff:ffff:ffff
1722aec:ab::/322aec:ab:ffff:ffff:ffff:ffff:ffff:ffff
1732aec:ac::/322aec:ac:ffff:ffff:ffff:ffff:ffff:ffff
1742aec:ad::/322aec:ad:ffff:ffff:ffff:ffff:ffff:ffff
1752aec:ae::/322aec:ae:ffff:ffff:ffff:ffff:ffff:ffff
1762aec:af::/322aec:af:ffff:ffff:ffff:ffff:ffff:ffff
1772aec:b0::/322aec:b0:ffff:ffff:ffff:ffff:ffff:ffff
1782aec:b1::/322aec:b1:ffff:ffff:ffff:ffff:ffff:ffff
1792aec:b2::/322aec:b2:ffff:ffff:ffff:ffff:ffff:ffff
1802aec:b3::/322aec:b3:ffff:ffff:ffff:ffff:ffff:ffff
1812aec:b4::/322aec:b4:ffff:ffff:ffff:ffff:ffff:ffff
1822aec:b5::/322aec:b5:ffff:ffff:ffff:ffff:ffff:ffff
1832aec:b6::/322aec:b6:ffff:ffff:ffff:ffff:ffff:ffff
1842aec:b7::/322aec:b7:ffff:ffff:ffff:ffff:ffff:ffff
1852aec:b8::/322aec:b8:ffff:ffff:ffff:ffff:ffff:ffff
1862aec:b9::/322aec:b9:ffff:ffff:ffff:ffff:ffff:ffff
1872aec:ba::/322aec:ba:ffff:ffff:ffff:ffff:ffff:ffff
1882aec:bb::/322aec:bb:ffff:ffff:ffff:ffff:ffff:ffff
1892aec:bc::/322aec:bc:ffff:ffff:ffff:ffff:ffff:ffff
1902aec:bd::/322aec:bd:ffff:ffff:ffff:ffff:ffff:ffff
1912aec:be::/322aec:be:ffff:ffff:ffff:ffff:ffff:ffff
1922aec:bf::/322aec:bf:ffff:ffff:ffff:ffff:ffff:ffff
1932aec:c0::/322aec:c0:ffff:ffff:ffff:ffff:ffff:ffff
1942aec:c1::/322aec:c1:ffff:ffff:ffff:ffff:ffff:ffff
1952aec:c2::/322aec:c2:ffff:ffff:ffff:ffff:ffff:ffff
1962aec:c3::/322aec:c3:ffff:ffff:ffff:ffff:ffff:ffff
1972aec:c4::/322aec:c4:ffff:ffff:ffff:ffff:ffff:ffff
1982aec:c5::/322aec:c5:ffff:ffff:ffff:ffff:ffff:ffff
1992aec:c6::/322aec:c6:ffff:ffff:ffff:ffff:ffff:ffff
2002aec:c7::/322aec:c7:ffff:ffff:ffff:ffff:ffff:ffff
2012aec:c8::/322aec:c8:ffff:ffff:ffff:ffff:ffff:ffff
2022aec:c9::/322aec:c9:ffff:ffff:ffff:ffff:ffff:ffff
2032aec:ca::/322aec:ca:ffff:ffff:ffff:ffff:ffff:ffff
2042aec:cb::/322aec:cb:ffff:ffff:ffff:ffff:ffff:ffff
2052aec:cc::/322aec:cc:ffff:ffff:ffff:ffff:ffff:ffff
2062aec:cd::/322aec:cd:ffff:ffff:ffff:ffff:ffff:ffff
2072aec:ce::/322aec:ce:ffff:ffff:ffff:ffff:ffff:ffff
2082aec:cf::/322aec:cf:ffff:ffff:ffff:ffff:ffff:ffff
2092aec:d0::/322aec:d0:ffff:ffff:ffff:ffff:ffff:ffff
2102aec:d1::/322aec:d1:ffff:ffff:ffff:ffff:ffff:ffff
2112aec:d2::/322aec:d2:ffff:ffff:ffff:ffff:ffff:ffff
2122aec:d3::/322aec:d3:ffff:ffff:ffff:ffff:ffff:ffff
2132aec:d4::/322aec:d4:ffff:ffff:ffff:ffff:ffff:ffff
2142aec:d5::/322aec:d5:ffff:ffff:ffff:ffff:ffff:ffff
2152aec:d6::/322aec:d6:ffff:ffff:ffff:ffff:ffff:ffff
2162aec:d7::/322aec:d7:ffff:ffff:ffff:ffff:ffff:ffff
2172aec:d8::/322aec:d8:ffff:ffff:ffff:ffff:ffff:ffff
2182aec:d9::/322aec:d9:ffff:ffff:ffff:ffff:ffff:ffff
2192aec:da::/322aec:da:ffff:ffff:ffff:ffff:ffff:ffff
2202aec:db::/322aec:db:ffff:ffff:ffff:ffff:ffff:ffff
2212aec:dc::/322aec:dc:ffff:ffff:ffff:ffff:ffff:ffff
2222aec:dd::/322aec:dd:ffff:ffff:ffff:ffff:ffff:ffff
2232aec:de::/322aec:de:ffff:ffff:ffff:ffff:ffff:ffff
2242aec:df::/322aec:df:ffff:ffff:ffff:ffff:ffff:ffff
2252aec:e0::/322aec:e0:ffff:ffff:ffff:ffff:ffff:ffff
2262aec:e1::/322aec:e1:ffff:ffff:ffff:ffff:ffff:ffff
2272aec:e2::/322aec:e2:ffff:ffff:ffff:ffff:ffff:ffff
2282aec:e3::/322aec:e3:ffff:ffff:ffff:ffff:ffff:ffff
2292aec:e4::/322aec:e4:ffff:ffff:ffff:ffff:ffff:ffff
2302aec:e5::/322aec:e5:ffff:ffff:ffff:ffff:ffff:ffff
2312aec:e6::/322aec:e6:ffff:ffff:ffff:ffff:ffff:ffff
2322aec:e7::/322aec:e7:ffff:ffff:ffff:ffff:ffff:ffff
2332aec:e8::/322aec:e8:ffff:ffff:ffff:ffff:ffff:ffff
2342aec:e9::/322aec:e9:ffff:ffff:ffff:ffff:ffff:ffff
2352aec:ea::/322aec:ea:ffff:ffff:ffff:ffff:ffff:ffff
2362aec:eb::/322aec:eb:ffff:ffff:ffff:ffff:ffff:ffff
2372aec:ec::/322aec:ec:ffff:ffff:ffff:ffff:ffff:ffff
2382aec:ed::/322aec:ed:ffff:ffff:ffff:ffff:ffff:ffff
2392aec:ee::/322aec:ee:ffff:ffff:ffff:ffff:ffff:ffff
2402aec:ef::/322aec:ef:ffff:ffff:ffff:ffff:ffff:ffff
2412aec:f0::/322aec:f0:ffff:ffff:ffff:ffff:ffff:ffff
2422aec:f1::/322aec:f1:ffff:ffff:ffff:ffff:ffff:ffff
2432aec:f2::/322aec:f2:ffff:ffff:ffff:ffff:ffff:ffff
2442aec:f3::/322aec:f3:ffff:ffff:ffff:ffff:ffff:ffff
2452aec:f4::/322aec:f4:ffff:ffff:ffff:ffff:ffff:ffff
2462aec:f5::/322aec:f5:ffff:ffff:ffff:ffff:ffff:ffff
2472aec:f6::/322aec:f6:ffff:ffff:ffff:ffff:ffff:ffff
2482aec:f7::/322aec:f7:ffff:ffff:ffff:ffff:ffff:ffff
2492aec:f8::/322aec:f8:ffff:ffff:ffff:ffff:ffff:ffff
2502aec:f9::/322aec:f9:ffff:ffff:ffff:ffff:ffff:ffff
2512aec:fa::/322aec:fa:ffff:ffff:ffff:ffff:ffff:ffff
2522aec:fb::/322aec:fb:ffff:ffff:ffff:ffff:ffff:ffff
2532aec:fc::/322aec:fc:ffff:ffff:ffff:ffff:ffff:ffff
2542aec:fd::/322aec:fd:ffff:ffff:ffff:ffff:ffff:ffff
2552aec:fe::/322aec:fe:ffff:ffff:ffff:ffff:ffff:ffff
2562aec:ff::/322aec:ff: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.