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/7
Addresses2^121
/64 networks2^57
Network
3e00::/7
First address
3e00::
Last address
3fff: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
3e00:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
e.3.ip6.arpa
f.3.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)

3e00::/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetLast address
13e00::/163e00:ffff:ffff:ffff:ffff:ffff:ffff:ffff
23e01::/163e01:ffff:ffff:ffff:ffff:ffff:ffff:ffff
33e02::/163e02:ffff:ffff:ffff:ffff:ffff:ffff:ffff
43e03::/163e03:ffff:ffff:ffff:ffff:ffff:ffff:ffff
53e04::/163e04:ffff:ffff:ffff:ffff:ffff:ffff:ffff
63e05::/163e05:ffff:ffff:ffff:ffff:ffff:ffff:ffff
73e06::/163e06:ffff:ffff:ffff:ffff:ffff:ffff:ffff
83e07::/163e07:ffff:ffff:ffff:ffff:ffff:ffff:ffff
93e08::/163e08:ffff:ffff:ffff:ffff:ffff:ffff:ffff
103e09::/163e09:ffff:ffff:ffff:ffff:ffff:ffff:ffff
113e0a::/163e0a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
123e0b::/163e0b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
133e0c::/163e0c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
143e0d::/163e0d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
153e0e::/163e0e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
163e0f::/163e0f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
173e10::/163e10:ffff:ffff:ffff:ffff:ffff:ffff:ffff
183e11::/163e11:ffff:ffff:ffff:ffff:ffff:ffff:ffff
193e12::/163e12:ffff:ffff:ffff:ffff:ffff:ffff:ffff
203e13::/163e13:ffff:ffff:ffff:ffff:ffff:ffff:ffff
213e14::/163e14:ffff:ffff:ffff:ffff:ffff:ffff:ffff
223e15::/163e15:ffff:ffff:ffff:ffff:ffff:ffff:ffff
233e16::/163e16:ffff:ffff:ffff:ffff:ffff:ffff:ffff
243e17::/163e17:ffff:ffff:ffff:ffff:ffff:ffff:ffff
253e18::/163e18:ffff:ffff:ffff:ffff:ffff:ffff:ffff
263e19::/163e19:ffff:ffff:ffff:ffff:ffff:ffff:ffff
273e1a::/163e1a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
283e1b::/163e1b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
293e1c::/163e1c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
303e1d::/163e1d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
313e1e::/163e1e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
323e1f::/163e1f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
333e20::/163e20:ffff:ffff:ffff:ffff:ffff:ffff:ffff
343e21::/163e21:ffff:ffff:ffff:ffff:ffff:ffff:ffff
353e22::/163e22:ffff:ffff:ffff:ffff:ffff:ffff:ffff
363e23::/163e23:ffff:ffff:ffff:ffff:ffff:ffff:ffff
373e24::/163e24:ffff:ffff:ffff:ffff:ffff:ffff:ffff
383e25::/163e25:ffff:ffff:ffff:ffff:ffff:ffff:ffff
393e26::/163e26:ffff:ffff:ffff:ffff:ffff:ffff:ffff
403e27::/163e27:ffff:ffff:ffff:ffff:ffff:ffff:ffff
413e28::/163e28:ffff:ffff:ffff:ffff:ffff:ffff:ffff
423e29::/163e29:ffff:ffff:ffff:ffff:ffff:ffff:ffff
433e2a::/163e2a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
443e2b::/163e2b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
453e2c::/163e2c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
463e2d::/163e2d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
473e2e::/163e2e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
483e2f::/163e2f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
493e30::/163e30:ffff:ffff:ffff:ffff:ffff:ffff:ffff
503e31::/163e31:ffff:ffff:ffff:ffff:ffff:ffff:ffff
513e32::/163e32:ffff:ffff:ffff:ffff:ffff:ffff:ffff
523e33::/163e33:ffff:ffff:ffff:ffff:ffff:ffff:ffff
533e34::/163e34:ffff:ffff:ffff:ffff:ffff:ffff:ffff
543e35::/163e35:ffff:ffff:ffff:ffff:ffff:ffff:ffff
553e36::/163e36:ffff:ffff:ffff:ffff:ffff:ffff:ffff
563e37::/163e37:ffff:ffff:ffff:ffff:ffff:ffff:ffff
573e38::/163e38:ffff:ffff:ffff:ffff:ffff:ffff:ffff
583e39::/163e39:ffff:ffff:ffff:ffff:ffff:ffff:ffff
593e3a::/163e3a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
603e3b::/163e3b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
613e3c::/163e3c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
623e3d::/163e3d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
633e3e::/163e3e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
643e3f::/163e3f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
653e40::/163e40:ffff:ffff:ffff:ffff:ffff:ffff:ffff
663e41::/163e41:ffff:ffff:ffff:ffff:ffff:ffff:ffff
673e42::/163e42:ffff:ffff:ffff:ffff:ffff:ffff:ffff
683e43::/163e43:ffff:ffff:ffff:ffff:ffff:ffff:ffff
693e44::/163e44:ffff:ffff:ffff:ffff:ffff:ffff:ffff
703e45::/163e45:ffff:ffff:ffff:ffff:ffff:ffff:ffff
713e46::/163e46:ffff:ffff:ffff:ffff:ffff:ffff:ffff
723e47::/163e47:ffff:ffff:ffff:ffff:ffff:ffff:ffff
733e48::/163e48:ffff:ffff:ffff:ffff:ffff:ffff:ffff
743e49::/163e49:ffff:ffff:ffff:ffff:ffff:ffff:ffff
753e4a::/163e4a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
763e4b::/163e4b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
773e4c::/163e4c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
783e4d::/163e4d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
793e4e::/163e4e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
803e4f::/163e4f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
813e50::/163e50:ffff:ffff:ffff:ffff:ffff:ffff:ffff
823e51::/163e51:ffff:ffff:ffff:ffff:ffff:ffff:ffff
833e52::/163e52:ffff:ffff:ffff:ffff:ffff:ffff:ffff
843e53::/163e53:ffff:ffff:ffff:ffff:ffff:ffff:ffff
853e54::/163e54:ffff:ffff:ffff:ffff:ffff:ffff:ffff
863e55::/163e55:ffff:ffff:ffff:ffff:ffff:ffff:ffff
873e56::/163e56:ffff:ffff:ffff:ffff:ffff:ffff:ffff
883e57::/163e57:ffff:ffff:ffff:ffff:ffff:ffff:ffff
893e58::/163e58:ffff:ffff:ffff:ffff:ffff:ffff:ffff
903e59::/163e59:ffff:ffff:ffff:ffff:ffff:ffff:ffff
913e5a::/163e5a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
923e5b::/163e5b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
933e5c::/163e5c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
943e5d::/163e5d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
953e5e::/163e5e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
963e5f::/163e5f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
973e60::/163e60:ffff:ffff:ffff:ffff:ffff:ffff:ffff
983e61::/163e61:ffff:ffff:ffff:ffff:ffff:ffff:ffff
993e62::/163e62:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1003e63::/163e63:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1013e64::/163e64:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1023e65::/163e65:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1033e66::/163e66:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1043e67::/163e67:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1053e68::/163e68:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1063e69::/163e69:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1073e6a::/163e6a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1083e6b::/163e6b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1093e6c::/163e6c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1103e6d::/163e6d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1113e6e::/163e6e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1123e6f::/163e6f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1133e70::/163e70:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1143e71::/163e71:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1153e72::/163e72:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1163e73::/163e73:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1173e74::/163e74:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1183e75::/163e75:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1193e76::/163e76:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1203e77::/163e77:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1213e78::/163e78:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1223e79::/163e79:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1233e7a::/163e7a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1243e7b::/163e7b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1253e7c::/163e7c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1263e7d::/163e7d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1273e7e::/163e7e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1283e7f::/163e7f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1293e80::/163e80:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1303e81::/163e81:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1313e82::/163e82:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1323e83::/163e83:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1333e84::/163e84:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1343e85::/163e85:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1353e86::/163e86:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1363e87::/163e87:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1373e88::/163e88:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1383e89::/163e89:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1393e8a::/163e8a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1403e8b::/163e8b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1413e8c::/163e8c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1423e8d::/163e8d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1433e8e::/163e8e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1443e8f::/163e8f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1453e90::/163e90:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1463e91::/163e91:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1473e92::/163e92:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1483e93::/163e93:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1493e94::/163e94:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1503e95::/163e95:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1513e96::/163e96:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1523e97::/163e97:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1533e98::/163e98:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1543e99::/163e99:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1553e9a::/163e9a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1563e9b::/163e9b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1573e9c::/163e9c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1583e9d::/163e9d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1593e9e::/163e9e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1603e9f::/163e9f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1613ea0::/163ea0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1623ea1::/163ea1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1633ea2::/163ea2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1643ea3::/163ea3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1653ea4::/163ea4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1663ea5::/163ea5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1673ea6::/163ea6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1683ea7::/163ea7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1693ea8::/163ea8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1703ea9::/163ea9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1713eaa::/163eaa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1723eab::/163eab:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1733eac::/163eac:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1743ead::/163ead:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1753eae::/163eae:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1763eaf::/163eaf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1773eb0::/163eb0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1783eb1::/163eb1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1793eb2::/163eb2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1803eb3::/163eb3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1813eb4::/163eb4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1823eb5::/163eb5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1833eb6::/163eb6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1843eb7::/163eb7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1853eb8::/163eb8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1863eb9::/163eb9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1873eba::/163eba:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1883ebb::/163ebb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1893ebc::/163ebc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1903ebd::/163ebd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1913ebe::/163ebe:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1923ebf::/163ebf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1933ec0::/163ec0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1943ec1::/163ec1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1953ec2::/163ec2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1963ec3::/163ec3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1973ec4::/163ec4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1983ec5::/163ec5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1993ec6::/163ec6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2003ec7::/163ec7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2013ec8::/163ec8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2023ec9::/163ec9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2033eca::/163eca:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2043ecb::/163ecb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2053ecc::/163ecc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2063ecd::/163ecd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2073ece::/163ece:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2083ecf::/163ecf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2093ed0::/163ed0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2103ed1::/163ed1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2113ed2::/163ed2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2123ed3::/163ed3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2133ed4::/163ed4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2143ed5::/163ed5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2153ed6::/163ed6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2163ed7::/163ed7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2173ed8::/163ed8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2183ed9::/163ed9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2193eda::/163eda:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2203edb::/163edb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2213edc::/163edc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2223edd::/163edd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2233ede::/163ede:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2243edf::/163edf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2253ee0::/163ee0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2263ee1::/163ee1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2273ee2::/163ee2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2283ee3::/163ee3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2293ee4::/163ee4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2303ee5::/163ee5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2313ee6::/163ee6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2323ee7::/163ee7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2333ee8::/163ee8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2343ee9::/163ee9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2353eea::/163eea:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2363eeb::/163eeb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2373eec::/163eec:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2383eed::/163eed:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2393eee::/163eee:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2403eef::/163eef:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2413ef0::/163ef0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2423ef1::/163ef1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2433ef2::/163ef2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2443ef3::/163ef3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2453ef4::/163ef4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2463ef5::/163ef5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2473ef6::/163ef6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2483ef7::/163ef7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2493ef8::/163ef8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2503ef9::/163ef9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2513efa::/163efa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2523efb::/163efb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2533efc::/163efc:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2543efd::/163efd:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2553efe::/163efe:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2563eff::/163eff: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.