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.

Network1.204.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
1.204.0.0
Broadcast address
1.207.255.255
First usable
1.204.0.1
Last usable
1.207.255.254
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 01CC0000 · Integer 30146560 to 30408703
Reverse DNS zones
204.1.in-addr.arpa
205.1.in-addr.arpa
206.1.in-addr.arpa
207.1.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
Address00000001.11001100.00000000.000000001.204.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network00000001.11001100.00000000.000000001.204.0.0
Broadcast00000001.11001111.11111111.111111111.207.255.255
Split into smaller subnets/24
/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)

1.204.0.0/14 makes 1,024 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
11.204.0.0/241.204.0.1 to 1.204.0.2541.204.0.255254
21.204.1.0/241.204.1.1 to 1.204.1.2541.204.1.255254
31.204.2.0/241.204.2.1 to 1.204.2.2541.204.2.255254
41.204.3.0/241.204.3.1 to 1.204.3.2541.204.3.255254
51.204.4.0/241.204.4.1 to 1.204.4.2541.204.4.255254
61.204.5.0/241.204.5.1 to 1.204.5.2541.204.5.255254
71.204.6.0/241.204.6.1 to 1.204.6.2541.204.6.255254
81.204.7.0/241.204.7.1 to 1.204.7.2541.204.7.255254
91.204.8.0/241.204.8.1 to 1.204.8.2541.204.8.255254
101.204.9.0/241.204.9.1 to 1.204.9.2541.204.9.255254
111.204.10.0/241.204.10.1 to 1.204.10.2541.204.10.255254
121.204.11.0/241.204.11.1 to 1.204.11.2541.204.11.255254
131.204.12.0/241.204.12.1 to 1.204.12.2541.204.12.255254
141.204.13.0/241.204.13.1 to 1.204.13.2541.204.13.255254
151.204.14.0/241.204.14.1 to 1.204.14.2541.204.14.255254
161.204.15.0/241.204.15.1 to 1.204.15.2541.204.15.255254
171.204.16.0/241.204.16.1 to 1.204.16.2541.204.16.255254
181.204.17.0/241.204.17.1 to 1.204.17.2541.204.17.255254
191.204.18.0/241.204.18.1 to 1.204.18.2541.204.18.255254
201.204.19.0/241.204.19.1 to 1.204.19.2541.204.19.255254
211.204.20.0/241.204.20.1 to 1.204.20.2541.204.20.255254
221.204.21.0/241.204.21.1 to 1.204.21.2541.204.21.255254
231.204.22.0/241.204.22.1 to 1.204.22.2541.204.22.255254
241.204.23.0/241.204.23.1 to 1.204.23.2541.204.23.255254
251.204.24.0/241.204.24.1 to 1.204.24.2541.204.24.255254
261.204.25.0/241.204.25.1 to 1.204.25.2541.204.25.255254
271.204.26.0/241.204.26.1 to 1.204.26.2541.204.26.255254
281.204.27.0/241.204.27.1 to 1.204.27.2541.204.27.255254
291.204.28.0/241.204.28.1 to 1.204.28.2541.204.28.255254
301.204.29.0/241.204.29.1 to 1.204.29.2541.204.29.255254
311.204.30.0/241.204.30.1 to 1.204.30.2541.204.30.255254
321.204.31.0/241.204.31.1 to 1.204.31.2541.204.31.255254
331.204.32.0/241.204.32.1 to 1.204.32.2541.204.32.255254
341.204.33.0/241.204.33.1 to 1.204.33.2541.204.33.255254
351.204.34.0/241.204.34.1 to 1.204.34.2541.204.34.255254
361.204.35.0/241.204.35.1 to 1.204.35.2541.204.35.255254
371.204.36.0/241.204.36.1 to 1.204.36.2541.204.36.255254
381.204.37.0/241.204.37.1 to 1.204.37.2541.204.37.255254
391.204.38.0/241.204.38.1 to 1.204.38.2541.204.38.255254
401.204.39.0/241.204.39.1 to 1.204.39.2541.204.39.255254
411.204.40.0/241.204.40.1 to 1.204.40.2541.204.40.255254
421.204.41.0/241.204.41.1 to 1.204.41.2541.204.41.255254
431.204.42.0/241.204.42.1 to 1.204.42.2541.204.42.255254
441.204.43.0/241.204.43.1 to 1.204.43.2541.204.43.255254
451.204.44.0/241.204.44.1 to 1.204.44.2541.204.44.255254
461.204.45.0/241.204.45.1 to 1.204.45.2541.204.45.255254
471.204.46.0/241.204.46.1 to 1.204.46.2541.204.46.255254
481.204.47.0/241.204.47.1 to 1.204.47.2541.204.47.255254
491.204.48.0/241.204.48.1 to 1.204.48.2541.204.48.255254
501.204.49.0/241.204.49.1 to 1.204.49.2541.204.49.255254
511.204.50.0/241.204.50.1 to 1.204.50.2541.204.50.255254
521.204.51.0/241.204.51.1 to 1.204.51.2541.204.51.255254
531.204.52.0/241.204.52.1 to 1.204.52.2541.204.52.255254
541.204.53.0/241.204.53.1 to 1.204.53.2541.204.53.255254
551.204.54.0/241.204.54.1 to 1.204.54.2541.204.54.255254
561.204.55.0/241.204.55.1 to 1.204.55.2541.204.55.255254
571.204.56.0/241.204.56.1 to 1.204.56.2541.204.56.255254
581.204.57.0/241.204.57.1 to 1.204.57.2541.204.57.255254
591.204.58.0/241.204.58.1 to 1.204.58.2541.204.58.255254
601.204.59.0/241.204.59.1 to 1.204.59.2541.204.59.255254
611.204.60.0/241.204.60.1 to 1.204.60.2541.204.60.255254
621.204.61.0/241.204.61.1 to 1.204.61.2541.204.61.255254
631.204.62.0/241.204.62.1 to 1.204.62.2541.204.62.255254
641.204.63.0/241.204.63.1 to 1.204.63.2541.204.63.255254
651.204.64.0/241.204.64.1 to 1.204.64.2541.204.64.255254
661.204.65.0/241.204.65.1 to 1.204.65.2541.204.65.255254
671.204.66.0/241.204.66.1 to 1.204.66.2541.204.66.255254
681.204.67.0/241.204.67.1 to 1.204.67.2541.204.67.255254
691.204.68.0/241.204.68.1 to 1.204.68.2541.204.68.255254
701.204.69.0/241.204.69.1 to 1.204.69.2541.204.69.255254
711.204.70.0/241.204.70.1 to 1.204.70.2541.204.70.255254
721.204.71.0/241.204.71.1 to 1.204.71.2541.204.71.255254
731.204.72.0/241.204.72.1 to 1.204.72.2541.204.72.255254
741.204.73.0/241.204.73.1 to 1.204.73.2541.204.73.255254
751.204.74.0/241.204.74.1 to 1.204.74.2541.204.74.255254
761.204.75.0/241.204.75.1 to 1.204.75.2541.204.75.255254
771.204.76.0/241.204.76.1 to 1.204.76.2541.204.76.255254
781.204.77.0/241.204.77.1 to 1.204.77.2541.204.77.255254
791.204.78.0/241.204.78.1 to 1.204.78.2541.204.78.255254
801.204.79.0/241.204.79.1 to 1.204.79.2541.204.79.255254
811.204.80.0/241.204.80.1 to 1.204.80.2541.204.80.255254
821.204.81.0/241.204.81.1 to 1.204.81.2541.204.81.255254
831.204.82.0/241.204.82.1 to 1.204.82.2541.204.82.255254
841.204.83.0/241.204.83.1 to 1.204.83.2541.204.83.255254
851.204.84.0/241.204.84.1 to 1.204.84.2541.204.84.255254
861.204.85.0/241.204.85.1 to 1.204.85.2541.204.85.255254
871.204.86.0/241.204.86.1 to 1.204.86.2541.204.86.255254
881.204.87.0/241.204.87.1 to 1.204.87.2541.204.87.255254
891.204.88.0/241.204.88.1 to 1.204.88.2541.204.88.255254
901.204.89.0/241.204.89.1 to 1.204.89.2541.204.89.255254
911.204.90.0/241.204.90.1 to 1.204.90.2541.204.90.255254
921.204.91.0/241.204.91.1 to 1.204.91.2541.204.91.255254
931.204.92.0/241.204.92.1 to 1.204.92.2541.204.92.255254
941.204.93.0/241.204.93.1 to 1.204.93.2541.204.93.255254
951.204.94.0/241.204.94.1 to 1.204.94.2541.204.94.255254
961.204.95.0/241.204.95.1 to 1.204.95.2541.204.95.255254
971.204.96.0/241.204.96.1 to 1.204.96.2541.204.96.255254
981.204.97.0/241.204.97.1 to 1.204.97.2541.204.97.255254
991.204.98.0/241.204.98.1 to 1.204.98.2541.204.98.255254
1001.204.99.0/241.204.99.1 to 1.204.99.2541.204.99.255254
1011.204.100.0/241.204.100.1 to 1.204.100.2541.204.100.255254
1021.204.101.0/241.204.101.1 to 1.204.101.2541.204.101.255254
1031.204.102.0/241.204.102.1 to 1.204.102.2541.204.102.255254
1041.204.103.0/241.204.103.1 to 1.204.103.2541.204.103.255254
1051.204.104.0/241.204.104.1 to 1.204.104.2541.204.104.255254
1061.204.105.0/241.204.105.1 to 1.204.105.2541.204.105.255254
1071.204.106.0/241.204.106.1 to 1.204.106.2541.204.106.255254
1081.204.107.0/241.204.107.1 to 1.204.107.2541.204.107.255254
1091.204.108.0/241.204.108.1 to 1.204.108.2541.204.108.255254
1101.204.109.0/241.204.109.1 to 1.204.109.2541.204.109.255254
1111.204.110.0/241.204.110.1 to 1.204.110.2541.204.110.255254
1121.204.111.0/241.204.111.1 to 1.204.111.2541.204.111.255254
1131.204.112.0/241.204.112.1 to 1.204.112.2541.204.112.255254
1141.204.113.0/241.204.113.1 to 1.204.113.2541.204.113.255254
1151.204.114.0/241.204.114.1 to 1.204.114.2541.204.114.255254
1161.204.115.0/241.204.115.1 to 1.204.115.2541.204.115.255254
1171.204.116.0/241.204.116.1 to 1.204.116.2541.204.116.255254
1181.204.117.0/241.204.117.1 to 1.204.117.2541.204.117.255254
1191.204.118.0/241.204.118.1 to 1.204.118.2541.204.118.255254
1201.204.119.0/241.204.119.1 to 1.204.119.2541.204.119.255254
1211.204.120.0/241.204.120.1 to 1.204.120.2541.204.120.255254
1221.204.121.0/241.204.121.1 to 1.204.121.2541.204.121.255254
1231.204.122.0/241.204.122.1 to 1.204.122.2541.204.122.255254
1241.204.123.0/241.204.123.1 to 1.204.123.2541.204.123.255254
1251.204.124.0/241.204.124.1 to 1.204.124.2541.204.124.255254
1261.204.125.0/241.204.125.1 to 1.204.125.2541.204.125.255254
1271.204.126.0/241.204.126.1 to 1.204.126.2541.204.126.255254
1281.204.127.0/241.204.127.1 to 1.204.127.2541.204.127.255254
1291.204.128.0/241.204.128.1 to 1.204.128.2541.204.128.255254
1301.204.129.0/241.204.129.1 to 1.204.129.2541.204.129.255254
1311.204.130.0/241.204.130.1 to 1.204.130.2541.204.130.255254
1321.204.131.0/241.204.131.1 to 1.204.131.2541.204.131.255254
1331.204.132.0/241.204.132.1 to 1.204.132.2541.204.132.255254
1341.204.133.0/241.204.133.1 to 1.204.133.2541.204.133.255254
1351.204.134.0/241.204.134.1 to 1.204.134.2541.204.134.255254
1361.204.135.0/241.204.135.1 to 1.204.135.2541.204.135.255254
1371.204.136.0/241.204.136.1 to 1.204.136.2541.204.136.255254
1381.204.137.0/241.204.137.1 to 1.204.137.2541.204.137.255254
1391.204.138.0/241.204.138.1 to 1.204.138.2541.204.138.255254
1401.204.139.0/241.204.139.1 to 1.204.139.2541.204.139.255254
1411.204.140.0/241.204.140.1 to 1.204.140.2541.204.140.255254
1421.204.141.0/241.204.141.1 to 1.204.141.2541.204.141.255254
1431.204.142.0/241.204.142.1 to 1.204.142.2541.204.142.255254
1441.204.143.0/241.204.143.1 to 1.204.143.2541.204.143.255254
1451.204.144.0/241.204.144.1 to 1.204.144.2541.204.144.255254
1461.204.145.0/241.204.145.1 to 1.204.145.2541.204.145.255254
1471.204.146.0/241.204.146.1 to 1.204.146.2541.204.146.255254
1481.204.147.0/241.204.147.1 to 1.204.147.2541.204.147.255254
1491.204.148.0/241.204.148.1 to 1.204.148.2541.204.148.255254
1501.204.149.0/241.204.149.1 to 1.204.149.2541.204.149.255254
1511.204.150.0/241.204.150.1 to 1.204.150.2541.204.150.255254
1521.204.151.0/241.204.151.1 to 1.204.151.2541.204.151.255254
1531.204.152.0/241.204.152.1 to 1.204.152.2541.204.152.255254
1541.204.153.0/241.204.153.1 to 1.204.153.2541.204.153.255254
1551.204.154.0/241.204.154.1 to 1.204.154.2541.204.154.255254
1561.204.155.0/241.204.155.1 to 1.204.155.2541.204.155.255254
1571.204.156.0/241.204.156.1 to 1.204.156.2541.204.156.255254
1581.204.157.0/241.204.157.1 to 1.204.157.2541.204.157.255254
1591.204.158.0/241.204.158.1 to 1.204.158.2541.204.158.255254
1601.204.159.0/241.204.159.1 to 1.204.159.2541.204.159.255254
1611.204.160.0/241.204.160.1 to 1.204.160.2541.204.160.255254
1621.204.161.0/241.204.161.1 to 1.204.161.2541.204.161.255254
1631.204.162.0/241.204.162.1 to 1.204.162.2541.204.162.255254
1641.204.163.0/241.204.163.1 to 1.204.163.2541.204.163.255254
1651.204.164.0/241.204.164.1 to 1.204.164.2541.204.164.255254
1661.204.165.0/241.204.165.1 to 1.204.165.2541.204.165.255254
1671.204.166.0/241.204.166.1 to 1.204.166.2541.204.166.255254
1681.204.167.0/241.204.167.1 to 1.204.167.2541.204.167.255254
1691.204.168.0/241.204.168.1 to 1.204.168.2541.204.168.255254
1701.204.169.0/241.204.169.1 to 1.204.169.2541.204.169.255254
1711.204.170.0/241.204.170.1 to 1.204.170.2541.204.170.255254
1721.204.171.0/241.204.171.1 to 1.204.171.2541.204.171.255254
1731.204.172.0/241.204.172.1 to 1.204.172.2541.204.172.255254
1741.204.173.0/241.204.173.1 to 1.204.173.2541.204.173.255254
1751.204.174.0/241.204.174.1 to 1.204.174.2541.204.174.255254
1761.204.175.0/241.204.175.1 to 1.204.175.2541.204.175.255254
1771.204.176.0/241.204.176.1 to 1.204.176.2541.204.176.255254
1781.204.177.0/241.204.177.1 to 1.204.177.2541.204.177.255254
1791.204.178.0/241.204.178.1 to 1.204.178.2541.204.178.255254
1801.204.179.0/241.204.179.1 to 1.204.179.2541.204.179.255254
1811.204.180.0/241.204.180.1 to 1.204.180.2541.204.180.255254
1821.204.181.0/241.204.181.1 to 1.204.181.2541.204.181.255254
1831.204.182.0/241.204.182.1 to 1.204.182.2541.204.182.255254
1841.204.183.0/241.204.183.1 to 1.204.183.2541.204.183.255254
1851.204.184.0/241.204.184.1 to 1.204.184.2541.204.184.255254
1861.204.185.0/241.204.185.1 to 1.204.185.2541.204.185.255254
1871.204.186.0/241.204.186.1 to 1.204.186.2541.204.186.255254
1881.204.187.0/241.204.187.1 to 1.204.187.2541.204.187.255254
1891.204.188.0/241.204.188.1 to 1.204.188.2541.204.188.255254
1901.204.189.0/241.204.189.1 to 1.204.189.2541.204.189.255254
1911.204.190.0/241.204.190.1 to 1.204.190.2541.204.190.255254
1921.204.191.0/241.204.191.1 to 1.204.191.2541.204.191.255254
1931.204.192.0/241.204.192.1 to 1.204.192.2541.204.192.255254
1941.204.193.0/241.204.193.1 to 1.204.193.2541.204.193.255254
1951.204.194.0/241.204.194.1 to 1.204.194.2541.204.194.255254
1961.204.195.0/241.204.195.1 to 1.204.195.2541.204.195.255254
1971.204.196.0/241.204.196.1 to 1.204.196.2541.204.196.255254
1981.204.197.0/241.204.197.1 to 1.204.197.2541.204.197.255254
1991.204.198.0/241.204.198.1 to 1.204.198.2541.204.198.255254
2001.204.199.0/241.204.199.1 to 1.204.199.2541.204.199.255254
2011.204.200.0/241.204.200.1 to 1.204.200.2541.204.200.255254
2021.204.201.0/241.204.201.1 to 1.204.201.2541.204.201.255254
2031.204.202.0/241.204.202.1 to 1.204.202.2541.204.202.255254
2041.204.203.0/241.204.203.1 to 1.204.203.2541.204.203.255254
2051.204.204.0/241.204.204.1 to 1.204.204.2541.204.204.255254
2061.204.205.0/241.204.205.1 to 1.204.205.2541.204.205.255254
2071.204.206.0/241.204.206.1 to 1.204.206.2541.204.206.255254
2081.204.207.0/241.204.207.1 to 1.204.207.2541.204.207.255254
2091.204.208.0/241.204.208.1 to 1.204.208.2541.204.208.255254
2101.204.209.0/241.204.209.1 to 1.204.209.2541.204.209.255254
2111.204.210.0/241.204.210.1 to 1.204.210.2541.204.210.255254
2121.204.211.0/241.204.211.1 to 1.204.211.2541.204.211.255254
2131.204.212.0/241.204.212.1 to 1.204.212.2541.204.212.255254
2141.204.213.0/241.204.213.1 to 1.204.213.2541.204.213.255254
2151.204.214.0/241.204.214.1 to 1.204.214.2541.204.214.255254
2161.204.215.0/241.204.215.1 to 1.204.215.2541.204.215.255254
2171.204.216.0/241.204.216.1 to 1.204.216.2541.204.216.255254
2181.204.217.0/241.204.217.1 to 1.204.217.2541.204.217.255254
2191.204.218.0/241.204.218.1 to 1.204.218.2541.204.218.255254
2201.204.219.0/241.204.219.1 to 1.204.219.2541.204.219.255254
2211.204.220.0/241.204.220.1 to 1.204.220.2541.204.220.255254
2221.204.221.0/241.204.221.1 to 1.204.221.2541.204.221.255254
2231.204.222.0/241.204.222.1 to 1.204.222.2541.204.222.255254
2241.204.223.0/241.204.223.1 to 1.204.223.2541.204.223.255254
2251.204.224.0/241.204.224.1 to 1.204.224.2541.204.224.255254
2261.204.225.0/241.204.225.1 to 1.204.225.2541.204.225.255254
2271.204.226.0/241.204.226.1 to 1.204.226.2541.204.226.255254
2281.204.227.0/241.204.227.1 to 1.204.227.2541.204.227.255254
2291.204.228.0/241.204.228.1 to 1.204.228.2541.204.228.255254
2301.204.229.0/241.204.229.1 to 1.204.229.2541.204.229.255254
2311.204.230.0/241.204.230.1 to 1.204.230.2541.204.230.255254
2321.204.231.0/241.204.231.1 to 1.204.231.2541.204.231.255254
2331.204.232.0/241.204.232.1 to 1.204.232.2541.204.232.255254
2341.204.233.0/241.204.233.1 to 1.204.233.2541.204.233.255254
2351.204.234.0/241.204.234.1 to 1.204.234.2541.204.234.255254
2361.204.235.0/241.204.235.1 to 1.204.235.2541.204.235.255254
2371.204.236.0/241.204.236.1 to 1.204.236.2541.204.236.255254
2381.204.237.0/241.204.237.1 to 1.204.237.2541.204.237.255254
2391.204.238.0/241.204.238.1 to 1.204.238.2541.204.238.255254
2401.204.239.0/241.204.239.1 to 1.204.239.2541.204.239.255254
2411.204.240.0/241.204.240.1 to 1.204.240.2541.204.240.255254
2421.204.241.0/241.204.241.1 to 1.204.241.2541.204.241.255254
2431.204.242.0/241.204.242.1 to 1.204.242.2541.204.242.255254
2441.204.243.0/241.204.243.1 to 1.204.243.2541.204.243.255254
2451.204.244.0/241.204.244.1 to 1.204.244.2541.204.244.255254
2461.204.245.0/241.204.245.1 to 1.204.245.2541.204.245.255254
2471.204.246.0/241.204.246.1 to 1.204.246.2541.204.246.255254
2481.204.247.0/241.204.247.1 to 1.204.247.2541.204.247.255254
2491.204.248.0/241.204.248.1 to 1.204.248.2541.204.248.255254
2501.204.249.0/241.204.249.1 to 1.204.249.2541.204.249.255254
2511.204.250.0/241.204.250.1 to 1.204.250.2541.204.250.255254
2521.204.251.0/241.204.251.1 to 1.204.251.2541.204.251.255254
2531.204.252.0/241.204.252.1 to 1.204.252.2541.204.252.255254
2541.204.253.0/241.204.253.1 to 1.204.253.2541.204.253.255254
2551.204.254.0/241.204.254.1 to 1.204.254.2541.204.254.255254
2561.204.255.0/241.204.255.1 to 1.204.255.2541.204.255.255254

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.