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.

Network8.72.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
8.72.0.0
Broadcast address
8.75.255.255
First usable
8.72.0.1
Last usable
8.75.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Public public
Old class
A (default /8)
As numbers
Hex 08480000 · Integer 138936320 to 139198463
Reverse DNS zones
72.8.in-addr.arpa
73.8.in-addr.arpa
74.8.in-addr.arpa
75.8.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001000.01001000.00000000.000000008.72.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network00001000.01001000.00000000.000000008.72.0.0
Broadcast00001000.01001011.11111111.111111118.75.255.255
Split into smaller subnets/22
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

8.72.0.0/14 makes 256 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
18.72.0.0/228.72.0.1 to 8.72.3.2548.72.3.2551,022
28.72.4.0/228.72.4.1 to 8.72.7.2548.72.7.2551,022
38.72.8.0/228.72.8.1 to 8.72.11.2548.72.11.2551,022
48.72.12.0/228.72.12.1 to 8.72.15.2548.72.15.2551,022
58.72.16.0/228.72.16.1 to 8.72.19.2548.72.19.2551,022
68.72.20.0/228.72.20.1 to 8.72.23.2548.72.23.2551,022
78.72.24.0/228.72.24.1 to 8.72.27.2548.72.27.2551,022
88.72.28.0/228.72.28.1 to 8.72.31.2548.72.31.2551,022
98.72.32.0/228.72.32.1 to 8.72.35.2548.72.35.2551,022
108.72.36.0/228.72.36.1 to 8.72.39.2548.72.39.2551,022
118.72.40.0/228.72.40.1 to 8.72.43.2548.72.43.2551,022
128.72.44.0/228.72.44.1 to 8.72.47.2548.72.47.2551,022
138.72.48.0/228.72.48.1 to 8.72.51.2548.72.51.2551,022
148.72.52.0/228.72.52.1 to 8.72.55.2548.72.55.2551,022
158.72.56.0/228.72.56.1 to 8.72.59.2548.72.59.2551,022
168.72.60.0/228.72.60.1 to 8.72.63.2548.72.63.2551,022
178.72.64.0/228.72.64.1 to 8.72.67.2548.72.67.2551,022
188.72.68.0/228.72.68.1 to 8.72.71.2548.72.71.2551,022
198.72.72.0/228.72.72.1 to 8.72.75.2548.72.75.2551,022
208.72.76.0/228.72.76.1 to 8.72.79.2548.72.79.2551,022
218.72.80.0/228.72.80.1 to 8.72.83.2548.72.83.2551,022
228.72.84.0/228.72.84.1 to 8.72.87.2548.72.87.2551,022
238.72.88.0/228.72.88.1 to 8.72.91.2548.72.91.2551,022
248.72.92.0/228.72.92.1 to 8.72.95.2548.72.95.2551,022
258.72.96.0/228.72.96.1 to 8.72.99.2548.72.99.2551,022
268.72.100.0/228.72.100.1 to 8.72.103.2548.72.103.2551,022
278.72.104.0/228.72.104.1 to 8.72.107.2548.72.107.2551,022
288.72.108.0/228.72.108.1 to 8.72.111.2548.72.111.2551,022
298.72.112.0/228.72.112.1 to 8.72.115.2548.72.115.2551,022
308.72.116.0/228.72.116.1 to 8.72.119.2548.72.119.2551,022
318.72.120.0/228.72.120.1 to 8.72.123.2548.72.123.2551,022
328.72.124.0/228.72.124.1 to 8.72.127.2548.72.127.2551,022
338.72.128.0/228.72.128.1 to 8.72.131.2548.72.131.2551,022
348.72.132.0/228.72.132.1 to 8.72.135.2548.72.135.2551,022
358.72.136.0/228.72.136.1 to 8.72.139.2548.72.139.2551,022
368.72.140.0/228.72.140.1 to 8.72.143.2548.72.143.2551,022
378.72.144.0/228.72.144.1 to 8.72.147.2548.72.147.2551,022
388.72.148.0/228.72.148.1 to 8.72.151.2548.72.151.2551,022
398.72.152.0/228.72.152.1 to 8.72.155.2548.72.155.2551,022
408.72.156.0/228.72.156.1 to 8.72.159.2548.72.159.2551,022
418.72.160.0/228.72.160.1 to 8.72.163.2548.72.163.2551,022
428.72.164.0/228.72.164.1 to 8.72.167.2548.72.167.2551,022
438.72.168.0/228.72.168.1 to 8.72.171.2548.72.171.2551,022
448.72.172.0/228.72.172.1 to 8.72.175.2548.72.175.2551,022
458.72.176.0/228.72.176.1 to 8.72.179.2548.72.179.2551,022
468.72.180.0/228.72.180.1 to 8.72.183.2548.72.183.2551,022
478.72.184.0/228.72.184.1 to 8.72.187.2548.72.187.2551,022
488.72.188.0/228.72.188.1 to 8.72.191.2548.72.191.2551,022
498.72.192.0/228.72.192.1 to 8.72.195.2548.72.195.2551,022
508.72.196.0/228.72.196.1 to 8.72.199.2548.72.199.2551,022
518.72.200.0/228.72.200.1 to 8.72.203.2548.72.203.2551,022
528.72.204.0/228.72.204.1 to 8.72.207.2548.72.207.2551,022
538.72.208.0/228.72.208.1 to 8.72.211.2548.72.211.2551,022
548.72.212.0/228.72.212.1 to 8.72.215.2548.72.215.2551,022
558.72.216.0/228.72.216.1 to 8.72.219.2548.72.219.2551,022
568.72.220.0/228.72.220.1 to 8.72.223.2548.72.223.2551,022
578.72.224.0/228.72.224.1 to 8.72.227.2548.72.227.2551,022
588.72.228.0/228.72.228.1 to 8.72.231.2548.72.231.2551,022
598.72.232.0/228.72.232.1 to 8.72.235.2548.72.235.2551,022
608.72.236.0/228.72.236.1 to 8.72.239.2548.72.239.2551,022
618.72.240.0/228.72.240.1 to 8.72.243.2548.72.243.2551,022
628.72.244.0/228.72.244.1 to 8.72.247.2548.72.247.2551,022
638.72.248.0/228.72.248.1 to 8.72.251.2548.72.251.2551,022
648.72.252.0/228.72.252.1 to 8.72.255.2548.72.255.2551,022
658.73.0.0/228.73.0.1 to 8.73.3.2548.73.3.2551,022
668.73.4.0/228.73.4.1 to 8.73.7.2548.73.7.2551,022
678.73.8.0/228.73.8.1 to 8.73.11.2548.73.11.2551,022
688.73.12.0/228.73.12.1 to 8.73.15.2548.73.15.2551,022
698.73.16.0/228.73.16.1 to 8.73.19.2548.73.19.2551,022
708.73.20.0/228.73.20.1 to 8.73.23.2548.73.23.2551,022
718.73.24.0/228.73.24.1 to 8.73.27.2548.73.27.2551,022
728.73.28.0/228.73.28.1 to 8.73.31.2548.73.31.2551,022
738.73.32.0/228.73.32.1 to 8.73.35.2548.73.35.2551,022
748.73.36.0/228.73.36.1 to 8.73.39.2548.73.39.2551,022
758.73.40.0/228.73.40.1 to 8.73.43.2548.73.43.2551,022
768.73.44.0/228.73.44.1 to 8.73.47.2548.73.47.2551,022
778.73.48.0/228.73.48.1 to 8.73.51.2548.73.51.2551,022
788.73.52.0/228.73.52.1 to 8.73.55.2548.73.55.2551,022
798.73.56.0/228.73.56.1 to 8.73.59.2548.73.59.2551,022
808.73.60.0/228.73.60.1 to 8.73.63.2548.73.63.2551,022
818.73.64.0/228.73.64.1 to 8.73.67.2548.73.67.2551,022
828.73.68.0/228.73.68.1 to 8.73.71.2548.73.71.2551,022
838.73.72.0/228.73.72.1 to 8.73.75.2548.73.75.2551,022
848.73.76.0/228.73.76.1 to 8.73.79.2548.73.79.2551,022
858.73.80.0/228.73.80.1 to 8.73.83.2548.73.83.2551,022
868.73.84.0/228.73.84.1 to 8.73.87.2548.73.87.2551,022
878.73.88.0/228.73.88.1 to 8.73.91.2548.73.91.2551,022
888.73.92.0/228.73.92.1 to 8.73.95.2548.73.95.2551,022
898.73.96.0/228.73.96.1 to 8.73.99.2548.73.99.2551,022
908.73.100.0/228.73.100.1 to 8.73.103.2548.73.103.2551,022
918.73.104.0/228.73.104.1 to 8.73.107.2548.73.107.2551,022
928.73.108.0/228.73.108.1 to 8.73.111.2548.73.111.2551,022
938.73.112.0/228.73.112.1 to 8.73.115.2548.73.115.2551,022
948.73.116.0/228.73.116.1 to 8.73.119.2548.73.119.2551,022
958.73.120.0/228.73.120.1 to 8.73.123.2548.73.123.2551,022
968.73.124.0/228.73.124.1 to 8.73.127.2548.73.127.2551,022
978.73.128.0/228.73.128.1 to 8.73.131.2548.73.131.2551,022
988.73.132.0/228.73.132.1 to 8.73.135.2548.73.135.2551,022
998.73.136.0/228.73.136.1 to 8.73.139.2548.73.139.2551,022
1008.73.140.0/228.73.140.1 to 8.73.143.2548.73.143.2551,022
1018.73.144.0/228.73.144.1 to 8.73.147.2548.73.147.2551,022
1028.73.148.0/228.73.148.1 to 8.73.151.2548.73.151.2551,022
1038.73.152.0/228.73.152.1 to 8.73.155.2548.73.155.2551,022
1048.73.156.0/228.73.156.1 to 8.73.159.2548.73.159.2551,022
1058.73.160.0/228.73.160.1 to 8.73.163.2548.73.163.2551,022
1068.73.164.0/228.73.164.1 to 8.73.167.2548.73.167.2551,022
1078.73.168.0/228.73.168.1 to 8.73.171.2548.73.171.2551,022
1088.73.172.0/228.73.172.1 to 8.73.175.2548.73.175.2551,022
1098.73.176.0/228.73.176.1 to 8.73.179.2548.73.179.2551,022
1108.73.180.0/228.73.180.1 to 8.73.183.2548.73.183.2551,022
1118.73.184.0/228.73.184.1 to 8.73.187.2548.73.187.2551,022
1128.73.188.0/228.73.188.1 to 8.73.191.2548.73.191.2551,022
1138.73.192.0/228.73.192.1 to 8.73.195.2548.73.195.2551,022
1148.73.196.0/228.73.196.1 to 8.73.199.2548.73.199.2551,022
1158.73.200.0/228.73.200.1 to 8.73.203.2548.73.203.2551,022
1168.73.204.0/228.73.204.1 to 8.73.207.2548.73.207.2551,022
1178.73.208.0/228.73.208.1 to 8.73.211.2548.73.211.2551,022
1188.73.212.0/228.73.212.1 to 8.73.215.2548.73.215.2551,022
1198.73.216.0/228.73.216.1 to 8.73.219.2548.73.219.2551,022
1208.73.220.0/228.73.220.1 to 8.73.223.2548.73.223.2551,022
1218.73.224.0/228.73.224.1 to 8.73.227.2548.73.227.2551,022
1228.73.228.0/228.73.228.1 to 8.73.231.2548.73.231.2551,022
1238.73.232.0/228.73.232.1 to 8.73.235.2548.73.235.2551,022
1248.73.236.0/228.73.236.1 to 8.73.239.2548.73.239.2551,022
1258.73.240.0/228.73.240.1 to 8.73.243.2548.73.243.2551,022
1268.73.244.0/228.73.244.1 to 8.73.247.2548.73.247.2551,022
1278.73.248.0/228.73.248.1 to 8.73.251.2548.73.251.2551,022
1288.73.252.0/228.73.252.1 to 8.73.255.2548.73.255.2551,022
1298.74.0.0/228.74.0.1 to 8.74.3.2548.74.3.2551,022
1308.74.4.0/228.74.4.1 to 8.74.7.2548.74.7.2551,022
1318.74.8.0/228.74.8.1 to 8.74.11.2548.74.11.2551,022
1328.74.12.0/228.74.12.1 to 8.74.15.2548.74.15.2551,022
1338.74.16.0/228.74.16.1 to 8.74.19.2548.74.19.2551,022
1348.74.20.0/228.74.20.1 to 8.74.23.2548.74.23.2551,022
1358.74.24.0/228.74.24.1 to 8.74.27.2548.74.27.2551,022
1368.74.28.0/228.74.28.1 to 8.74.31.2548.74.31.2551,022
1378.74.32.0/228.74.32.1 to 8.74.35.2548.74.35.2551,022
1388.74.36.0/228.74.36.1 to 8.74.39.2548.74.39.2551,022
1398.74.40.0/228.74.40.1 to 8.74.43.2548.74.43.2551,022
1408.74.44.0/228.74.44.1 to 8.74.47.2548.74.47.2551,022
1418.74.48.0/228.74.48.1 to 8.74.51.2548.74.51.2551,022
1428.74.52.0/228.74.52.1 to 8.74.55.2548.74.55.2551,022
1438.74.56.0/228.74.56.1 to 8.74.59.2548.74.59.2551,022
1448.74.60.0/228.74.60.1 to 8.74.63.2548.74.63.2551,022
1458.74.64.0/228.74.64.1 to 8.74.67.2548.74.67.2551,022
1468.74.68.0/228.74.68.1 to 8.74.71.2548.74.71.2551,022
1478.74.72.0/228.74.72.1 to 8.74.75.2548.74.75.2551,022
1488.74.76.0/228.74.76.1 to 8.74.79.2548.74.79.2551,022
1498.74.80.0/228.74.80.1 to 8.74.83.2548.74.83.2551,022
1508.74.84.0/228.74.84.1 to 8.74.87.2548.74.87.2551,022
1518.74.88.0/228.74.88.1 to 8.74.91.2548.74.91.2551,022
1528.74.92.0/228.74.92.1 to 8.74.95.2548.74.95.2551,022
1538.74.96.0/228.74.96.1 to 8.74.99.2548.74.99.2551,022
1548.74.100.0/228.74.100.1 to 8.74.103.2548.74.103.2551,022
1558.74.104.0/228.74.104.1 to 8.74.107.2548.74.107.2551,022
1568.74.108.0/228.74.108.1 to 8.74.111.2548.74.111.2551,022
1578.74.112.0/228.74.112.1 to 8.74.115.2548.74.115.2551,022
1588.74.116.0/228.74.116.1 to 8.74.119.2548.74.119.2551,022
1598.74.120.0/228.74.120.1 to 8.74.123.2548.74.123.2551,022
1608.74.124.0/228.74.124.1 to 8.74.127.2548.74.127.2551,022
1618.74.128.0/228.74.128.1 to 8.74.131.2548.74.131.2551,022
1628.74.132.0/228.74.132.1 to 8.74.135.2548.74.135.2551,022
1638.74.136.0/228.74.136.1 to 8.74.139.2548.74.139.2551,022
1648.74.140.0/228.74.140.1 to 8.74.143.2548.74.143.2551,022
1658.74.144.0/228.74.144.1 to 8.74.147.2548.74.147.2551,022
1668.74.148.0/228.74.148.1 to 8.74.151.2548.74.151.2551,022
1678.74.152.0/228.74.152.1 to 8.74.155.2548.74.155.2551,022
1688.74.156.0/228.74.156.1 to 8.74.159.2548.74.159.2551,022
1698.74.160.0/228.74.160.1 to 8.74.163.2548.74.163.2551,022
1708.74.164.0/228.74.164.1 to 8.74.167.2548.74.167.2551,022
1718.74.168.0/228.74.168.1 to 8.74.171.2548.74.171.2551,022
1728.74.172.0/228.74.172.1 to 8.74.175.2548.74.175.2551,022
1738.74.176.0/228.74.176.1 to 8.74.179.2548.74.179.2551,022
1748.74.180.0/228.74.180.1 to 8.74.183.2548.74.183.2551,022
1758.74.184.0/228.74.184.1 to 8.74.187.2548.74.187.2551,022
1768.74.188.0/228.74.188.1 to 8.74.191.2548.74.191.2551,022
1778.74.192.0/228.74.192.1 to 8.74.195.2548.74.195.2551,022
1788.74.196.0/228.74.196.1 to 8.74.199.2548.74.199.2551,022
1798.74.200.0/228.74.200.1 to 8.74.203.2548.74.203.2551,022
1808.74.204.0/228.74.204.1 to 8.74.207.2548.74.207.2551,022
1818.74.208.0/228.74.208.1 to 8.74.211.2548.74.211.2551,022
1828.74.212.0/228.74.212.1 to 8.74.215.2548.74.215.2551,022
1838.74.216.0/228.74.216.1 to 8.74.219.2548.74.219.2551,022
1848.74.220.0/228.74.220.1 to 8.74.223.2548.74.223.2551,022
1858.74.224.0/228.74.224.1 to 8.74.227.2548.74.227.2551,022
1868.74.228.0/228.74.228.1 to 8.74.231.2548.74.231.2551,022
1878.74.232.0/228.74.232.1 to 8.74.235.2548.74.235.2551,022
1888.74.236.0/228.74.236.1 to 8.74.239.2548.74.239.2551,022
1898.74.240.0/228.74.240.1 to 8.74.243.2548.74.243.2551,022
1908.74.244.0/228.74.244.1 to 8.74.247.2548.74.247.2551,022
1918.74.248.0/228.74.248.1 to 8.74.251.2548.74.251.2551,022
1928.74.252.0/228.74.252.1 to 8.74.255.2548.74.255.2551,022
1938.75.0.0/228.75.0.1 to 8.75.3.2548.75.3.2551,022
1948.75.4.0/228.75.4.1 to 8.75.7.2548.75.7.2551,022
1958.75.8.0/228.75.8.1 to 8.75.11.2548.75.11.2551,022
1968.75.12.0/228.75.12.1 to 8.75.15.2548.75.15.2551,022
1978.75.16.0/228.75.16.1 to 8.75.19.2548.75.19.2551,022
1988.75.20.0/228.75.20.1 to 8.75.23.2548.75.23.2551,022
1998.75.24.0/228.75.24.1 to 8.75.27.2548.75.27.2551,022
2008.75.28.0/228.75.28.1 to 8.75.31.2548.75.31.2551,022
2018.75.32.0/228.75.32.1 to 8.75.35.2548.75.35.2551,022
2028.75.36.0/228.75.36.1 to 8.75.39.2548.75.39.2551,022
2038.75.40.0/228.75.40.1 to 8.75.43.2548.75.43.2551,022
2048.75.44.0/228.75.44.1 to 8.75.47.2548.75.47.2551,022
2058.75.48.0/228.75.48.1 to 8.75.51.2548.75.51.2551,022
2068.75.52.0/228.75.52.1 to 8.75.55.2548.75.55.2551,022
2078.75.56.0/228.75.56.1 to 8.75.59.2548.75.59.2551,022
2088.75.60.0/228.75.60.1 to 8.75.63.2548.75.63.2551,022
2098.75.64.0/228.75.64.1 to 8.75.67.2548.75.67.2551,022
2108.75.68.0/228.75.68.1 to 8.75.71.2548.75.71.2551,022
2118.75.72.0/228.75.72.1 to 8.75.75.2548.75.75.2551,022
2128.75.76.0/228.75.76.1 to 8.75.79.2548.75.79.2551,022
2138.75.80.0/228.75.80.1 to 8.75.83.2548.75.83.2551,022
2148.75.84.0/228.75.84.1 to 8.75.87.2548.75.87.2551,022
2158.75.88.0/228.75.88.1 to 8.75.91.2548.75.91.2551,022
2168.75.92.0/228.75.92.1 to 8.75.95.2548.75.95.2551,022
2178.75.96.0/228.75.96.1 to 8.75.99.2548.75.99.2551,022
2188.75.100.0/228.75.100.1 to 8.75.103.2548.75.103.2551,022
2198.75.104.0/228.75.104.1 to 8.75.107.2548.75.107.2551,022
2208.75.108.0/228.75.108.1 to 8.75.111.2548.75.111.2551,022
2218.75.112.0/228.75.112.1 to 8.75.115.2548.75.115.2551,022
2228.75.116.0/228.75.116.1 to 8.75.119.2548.75.119.2551,022
2238.75.120.0/228.75.120.1 to 8.75.123.2548.75.123.2551,022
2248.75.124.0/228.75.124.1 to 8.75.127.2548.75.127.2551,022
2258.75.128.0/228.75.128.1 to 8.75.131.2548.75.131.2551,022
2268.75.132.0/228.75.132.1 to 8.75.135.2548.75.135.2551,022
2278.75.136.0/228.75.136.1 to 8.75.139.2548.75.139.2551,022
2288.75.140.0/228.75.140.1 to 8.75.143.2548.75.143.2551,022
2298.75.144.0/228.75.144.1 to 8.75.147.2548.75.147.2551,022
2308.75.148.0/228.75.148.1 to 8.75.151.2548.75.151.2551,022
2318.75.152.0/228.75.152.1 to 8.75.155.2548.75.155.2551,022
2328.75.156.0/228.75.156.1 to 8.75.159.2548.75.159.2551,022
2338.75.160.0/228.75.160.1 to 8.75.163.2548.75.163.2551,022
2348.75.164.0/228.75.164.1 to 8.75.167.2548.75.167.2551,022
2358.75.168.0/228.75.168.1 to 8.75.171.2548.75.171.2551,022
2368.75.172.0/228.75.172.1 to 8.75.175.2548.75.175.2551,022
2378.75.176.0/228.75.176.1 to 8.75.179.2548.75.179.2551,022
2388.75.180.0/228.75.180.1 to 8.75.183.2548.75.183.2551,022
2398.75.184.0/228.75.184.1 to 8.75.187.2548.75.187.2551,022
2408.75.188.0/228.75.188.1 to 8.75.191.2548.75.191.2551,022
2418.75.192.0/228.75.192.1 to 8.75.195.2548.75.195.2551,022
2428.75.196.0/228.75.196.1 to 8.75.199.2548.75.199.2551,022
2438.75.200.0/228.75.200.1 to 8.75.203.2548.75.203.2551,022
2448.75.204.0/228.75.204.1 to 8.75.207.2548.75.207.2551,022
2458.75.208.0/228.75.208.1 to 8.75.211.2548.75.211.2551,022
2468.75.212.0/228.75.212.1 to 8.75.215.2548.75.215.2551,022
2478.75.216.0/228.75.216.1 to 8.75.219.2548.75.219.2551,022
2488.75.220.0/228.75.220.1 to 8.75.223.2548.75.223.2551,022
2498.75.224.0/228.75.224.1 to 8.75.227.2548.75.227.2551,022
2508.75.228.0/228.75.228.1 to 8.75.231.2548.75.231.2551,022
2518.75.232.0/228.75.232.1 to 8.75.235.2548.75.235.2551,022
2528.75.236.0/228.75.236.1 to 8.75.239.2548.75.239.2551,022
2538.75.240.0/228.75.240.1 to 8.75.243.2548.75.243.2551,022
2548.75.244.0/228.75.244.1 to 8.75.247.2548.75.247.2551,022
2558.75.248.0/228.75.248.1 to 8.75.251.2548.75.251.2551,022
2568.75.252.0/228.75.252.1 to 8.75.255.2548.75.255.2551,022

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.