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.

Network16.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
16.0.0.0
Broadcast address
23.255.255.255
First usable
16.0.0.1
Last usable
23.255.255.254
Usable hosts
134,217,726 (134,217,728 less the network and broadcast addresses)
Subnet mask
248.0.0.0
Wildcard mask
7.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/5
Type
Public public
Old class
A (default /8)
As numbers
Hex 10000000 · Integer 268435456 to 402653183
Reverse DNS zones
16.in-addr.arpa
17.in-addr.arpa
18.in-addr.arpa
19.in-addr.arpa
20.in-addr.arpa
21.in-addr.arpa
22.in-addr.arpa
23.in-addr.arpa
/5 is not on a 8-bit boundary, so it takes 8 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010000.00000000.00000000.0000000016.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network00010000.00000000.00000000.0000000016.0.0.0
Broadcast00010111.11111111.11111111.1111111123.255.255.255
Split into smaller subnets/14
/6 (2)/7 (4)/8 (8)/9 (16)/10 (32)/11 (64)/12 (128)/13 (256)/14 (512)/15 (1,024)/16 (2,048)/17 (4,096)

16.0.0.0/5 makes 512 subnets of /14; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
116.0.0.0/1416.0.0.1 to 16.3.255.25416.3.255.255262,142
216.4.0.0/1416.4.0.1 to 16.7.255.25416.7.255.255262,142
316.8.0.0/1416.8.0.1 to 16.11.255.25416.11.255.255262,142
416.12.0.0/1416.12.0.1 to 16.15.255.25416.15.255.255262,142
516.16.0.0/1416.16.0.1 to 16.19.255.25416.19.255.255262,142
616.20.0.0/1416.20.0.1 to 16.23.255.25416.23.255.255262,142
716.24.0.0/1416.24.0.1 to 16.27.255.25416.27.255.255262,142
816.28.0.0/1416.28.0.1 to 16.31.255.25416.31.255.255262,142
916.32.0.0/1416.32.0.1 to 16.35.255.25416.35.255.255262,142
1016.36.0.0/1416.36.0.1 to 16.39.255.25416.39.255.255262,142
1116.40.0.0/1416.40.0.1 to 16.43.255.25416.43.255.255262,142
1216.44.0.0/1416.44.0.1 to 16.47.255.25416.47.255.255262,142
1316.48.0.0/1416.48.0.1 to 16.51.255.25416.51.255.255262,142
1416.52.0.0/1416.52.0.1 to 16.55.255.25416.55.255.255262,142
1516.56.0.0/1416.56.0.1 to 16.59.255.25416.59.255.255262,142
1616.60.0.0/1416.60.0.1 to 16.63.255.25416.63.255.255262,142
1716.64.0.0/1416.64.0.1 to 16.67.255.25416.67.255.255262,142
1816.68.0.0/1416.68.0.1 to 16.71.255.25416.71.255.255262,142
1916.72.0.0/1416.72.0.1 to 16.75.255.25416.75.255.255262,142
2016.76.0.0/1416.76.0.1 to 16.79.255.25416.79.255.255262,142
2116.80.0.0/1416.80.0.1 to 16.83.255.25416.83.255.255262,142
2216.84.0.0/1416.84.0.1 to 16.87.255.25416.87.255.255262,142
2316.88.0.0/1416.88.0.1 to 16.91.255.25416.91.255.255262,142
2416.92.0.0/1416.92.0.1 to 16.95.255.25416.95.255.255262,142
2516.96.0.0/1416.96.0.1 to 16.99.255.25416.99.255.255262,142
2616.100.0.0/1416.100.0.1 to 16.103.255.25416.103.255.255262,142
2716.104.0.0/1416.104.0.1 to 16.107.255.25416.107.255.255262,142
2816.108.0.0/1416.108.0.1 to 16.111.255.25416.111.255.255262,142
2916.112.0.0/1416.112.0.1 to 16.115.255.25416.115.255.255262,142
3016.116.0.0/1416.116.0.1 to 16.119.255.25416.119.255.255262,142
3116.120.0.0/1416.120.0.1 to 16.123.255.25416.123.255.255262,142
3216.124.0.0/1416.124.0.1 to 16.127.255.25416.127.255.255262,142
3316.128.0.0/1416.128.0.1 to 16.131.255.25416.131.255.255262,142
3416.132.0.0/1416.132.0.1 to 16.135.255.25416.135.255.255262,142
3516.136.0.0/1416.136.0.1 to 16.139.255.25416.139.255.255262,142
3616.140.0.0/1416.140.0.1 to 16.143.255.25416.143.255.255262,142
3716.144.0.0/1416.144.0.1 to 16.147.255.25416.147.255.255262,142
3816.148.0.0/1416.148.0.1 to 16.151.255.25416.151.255.255262,142
3916.152.0.0/1416.152.0.1 to 16.155.255.25416.155.255.255262,142
4016.156.0.0/1416.156.0.1 to 16.159.255.25416.159.255.255262,142
4116.160.0.0/1416.160.0.1 to 16.163.255.25416.163.255.255262,142
4216.164.0.0/1416.164.0.1 to 16.167.255.25416.167.255.255262,142
4316.168.0.0/1416.168.0.1 to 16.171.255.25416.171.255.255262,142
4416.172.0.0/1416.172.0.1 to 16.175.255.25416.175.255.255262,142
4516.176.0.0/1416.176.0.1 to 16.179.255.25416.179.255.255262,142
4616.180.0.0/1416.180.0.1 to 16.183.255.25416.183.255.255262,142
4716.184.0.0/1416.184.0.1 to 16.187.255.25416.187.255.255262,142
4816.188.0.0/1416.188.0.1 to 16.191.255.25416.191.255.255262,142
4916.192.0.0/1416.192.0.1 to 16.195.255.25416.195.255.255262,142
5016.196.0.0/1416.196.0.1 to 16.199.255.25416.199.255.255262,142
5116.200.0.0/1416.200.0.1 to 16.203.255.25416.203.255.255262,142
5216.204.0.0/1416.204.0.1 to 16.207.255.25416.207.255.255262,142
5316.208.0.0/1416.208.0.1 to 16.211.255.25416.211.255.255262,142
5416.212.0.0/1416.212.0.1 to 16.215.255.25416.215.255.255262,142
5516.216.0.0/1416.216.0.1 to 16.219.255.25416.219.255.255262,142
5616.220.0.0/1416.220.0.1 to 16.223.255.25416.223.255.255262,142
5716.224.0.0/1416.224.0.1 to 16.227.255.25416.227.255.255262,142
5816.228.0.0/1416.228.0.1 to 16.231.255.25416.231.255.255262,142
5916.232.0.0/1416.232.0.1 to 16.235.255.25416.235.255.255262,142
6016.236.0.0/1416.236.0.1 to 16.239.255.25416.239.255.255262,142
6116.240.0.0/1416.240.0.1 to 16.243.255.25416.243.255.255262,142
6216.244.0.0/1416.244.0.1 to 16.247.255.25416.247.255.255262,142
6316.248.0.0/1416.248.0.1 to 16.251.255.25416.251.255.255262,142
6416.252.0.0/1416.252.0.1 to 16.255.255.25416.255.255.255262,142
6517.0.0.0/1417.0.0.1 to 17.3.255.25417.3.255.255262,142
6617.4.0.0/1417.4.0.1 to 17.7.255.25417.7.255.255262,142
6717.8.0.0/1417.8.0.1 to 17.11.255.25417.11.255.255262,142
6817.12.0.0/1417.12.0.1 to 17.15.255.25417.15.255.255262,142
6917.16.0.0/1417.16.0.1 to 17.19.255.25417.19.255.255262,142
7017.20.0.0/1417.20.0.1 to 17.23.255.25417.23.255.255262,142
7117.24.0.0/1417.24.0.1 to 17.27.255.25417.27.255.255262,142
7217.28.0.0/1417.28.0.1 to 17.31.255.25417.31.255.255262,142
7317.32.0.0/1417.32.0.1 to 17.35.255.25417.35.255.255262,142
7417.36.0.0/1417.36.0.1 to 17.39.255.25417.39.255.255262,142
7517.40.0.0/1417.40.0.1 to 17.43.255.25417.43.255.255262,142
7617.44.0.0/1417.44.0.1 to 17.47.255.25417.47.255.255262,142
7717.48.0.0/1417.48.0.1 to 17.51.255.25417.51.255.255262,142
7817.52.0.0/1417.52.0.1 to 17.55.255.25417.55.255.255262,142
7917.56.0.0/1417.56.0.1 to 17.59.255.25417.59.255.255262,142
8017.60.0.0/1417.60.0.1 to 17.63.255.25417.63.255.255262,142
8117.64.0.0/1417.64.0.1 to 17.67.255.25417.67.255.255262,142
8217.68.0.0/1417.68.0.1 to 17.71.255.25417.71.255.255262,142
8317.72.0.0/1417.72.0.1 to 17.75.255.25417.75.255.255262,142
8417.76.0.0/1417.76.0.1 to 17.79.255.25417.79.255.255262,142
8517.80.0.0/1417.80.0.1 to 17.83.255.25417.83.255.255262,142
8617.84.0.0/1417.84.0.1 to 17.87.255.25417.87.255.255262,142
8717.88.0.0/1417.88.0.1 to 17.91.255.25417.91.255.255262,142
8817.92.0.0/1417.92.0.1 to 17.95.255.25417.95.255.255262,142
8917.96.0.0/1417.96.0.1 to 17.99.255.25417.99.255.255262,142
9017.100.0.0/1417.100.0.1 to 17.103.255.25417.103.255.255262,142
9117.104.0.0/1417.104.0.1 to 17.107.255.25417.107.255.255262,142
9217.108.0.0/1417.108.0.1 to 17.111.255.25417.111.255.255262,142
9317.112.0.0/1417.112.0.1 to 17.115.255.25417.115.255.255262,142
9417.116.0.0/1417.116.0.1 to 17.119.255.25417.119.255.255262,142
9517.120.0.0/1417.120.0.1 to 17.123.255.25417.123.255.255262,142
9617.124.0.0/1417.124.0.1 to 17.127.255.25417.127.255.255262,142
9717.128.0.0/1417.128.0.1 to 17.131.255.25417.131.255.255262,142
9817.132.0.0/1417.132.0.1 to 17.135.255.25417.135.255.255262,142
9917.136.0.0/1417.136.0.1 to 17.139.255.25417.139.255.255262,142
10017.140.0.0/1417.140.0.1 to 17.143.255.25417.143.255.255262,142
10117.144.0.0/1417.144.0.1 to 17.147.255.25417.147.255.255262,142
10217.148.0.0/1417.148.0.1 to 17.151.255.25417.151.255.255262,142
10317.152.0.0/1417.152.0.1 to 17.155.255.25417.155.255.255262,142
10417.156.0.0/1417.156.0.1 to 17.159.255.25417.159.255.255262,142
10517.160.0.0/1417.160.0.1 to 17.163.255.25417.163.255.255262,142
10617.164.0.0/1417.164.0.1 to 17.167.255.25417.167.255.255262,142
10717.168.0.0/1417.168.0.1 to 17.171.255.25417.171.255.255262,142
10817.172.0.0/1417.172.0.1 to 17.175.255.25417.175.255.255262,142
10917.176.0.0/1417.176.0.1 to 17.179.255.25417.179.255.255262,142
11017.180.0.0/1417.180.0.1 to 17.183.255.25417.183.255.255262,142
11117.184.0.0/1417.184.0.1 to 17.187.255.25417.187.255.255262,142
11217.188.0.0/1417.188.0.1 to 17.191.255.25417.191.255.255262,142
11317.192.0.0/1417.192.0.1 to 17.195.255.25417.195.255.255262,142
11417.196.0.0/1417.196.0.1 to 17.199.255.25417.199.255.255262,142
11517.200.0.0/1417.200.0.1 to 17.203.255.25417.203.255.255262,142
11617.204.0.0/1417.204.0.1 to 17.207.255.25417.207.255.255262,142
11717.208.0.0/1417.208.0.1 to 17.211.255.25417.211.255.255262,142
11817.212.0.0/1417.212.0.1 to 17.215.255.25417.215.255.255262,142
11917.216.0.0/1417.216.0.1 to 17.219.255.25417.219.255.255262,142
12017.220.0.0/1417.220.0.1 to 17.223.255.25417.223.255.255262,142
12117.224.0.0/1417.224.0.1 to 17.227.255.25417.227.255.255262,142
12217.228.0.0/1417.228.0.1 to 17.231.255.25417.231.255.255262,142
12317.232.0.0/1417.232.0.1 to 17.235.255.25417.235.255.255262,142
12417.236.0.0/1417.236.0.1 to 17.239.255.25417.239.255.255262,142
12517.240.0.0/1417.240.0.1 to 17.243.255.25417.243.255.255262,142
12617.244.0.0/1417.244.0.1 to 17.247.255.25417.247.255.255262,142
12717.248.0.0/1417.248.0.1 to 17.251.255.25417.251.255.255262,142
12817.252.0.0/1417.252.0.1 to 17.255.255.25417.255.255.255262,142
12918.0.0.0/1418.0.0.1 to 18.3.255.25418.3.255.255262,142
13018.4.0.0/1418.4.0.1 to 18.7.255.25418.7.255.255262,142
13118.8.0.0/1418.8.0.1 to 18.11.255.25418.11.255.255262,142
13218.12.0.0/1418.12.0.1 to 18.15.255.25418.15.255.255262,142
13318.16.0.0/1418.16.0.1 to 18.19.255.25418.19.255.255262,142
13418.20.0.0/1418.20.0.1 to 18.23.255.25418.23.255.255262,142
13518.24.0.0/1418.24.0.1 to 18.27.255.25418.27.255.255262,142
13618.28.0.0/1418.28.0.1 to 18.31.255.25418.31.255.255262,142
13718.32.0.0/1418.32.0.1 to 18.35.255.25418.35.255.255262,142
13818.36.0.0/1418.36.0.1 to 18.39.255.25418.39.255.255262,142
13918.40.0.0/1418.40.0.1 to 18.43.255.25418.43.255.255262,142
14018.44.0.0/1418.44.0.1 to 18.47.255.25418.47.255.255262,142
14118.48.0.0/1418.48.0.1 to 18.51.255.25418.51.255.255262,142
14218.52.0.0/1418.52.0.1 to 18.55.255.25418.55.255.255262,142
14318.56.0.0/1418.56.0.1 to 18.59.255.25418.59.255.255262,142
14418.60.0.0/1418.60.0.1 to 18.63.255.25418.63.255.255262,142
14518.64.0.0/1418.64.0.1 to 18.67.255.25418.67.255.255262,142
14618.68.0.0/1418.68.0.1 to 18.71.255.25418.71.255.255262,142
14718.72.0.0/1418.72.0.1 to 18.75.255.25418.75.255.255262,142
14818.76.0.0/1418.76.0.1 to 18.79.255.25418.79.255.255262,142
14918.80.0.0/1418.80.0.1 to 18.83.255.25418.83.255.255262,142
15018.84.0.0/1418.84.0.1 to 18.87.255.25418.87.255.255262,142
15118.88.0.0/1418.88.0.1 to 18.91.255.25418.91.255.255262,142
15218.92.0.0/1418.92.0.1 to 18.95.255.25418.95.255.255262,142
15318.96.0.0/1418.96.0.1 to 18.99.255.25418.99.255.255262,142
15418.100.0.0/1418.100.0.1 to 18.103.255.25418.103.255.255262,142
15518.104.0.0/1418.104.0.1 to 18.107.255.25418.107.255.255262,142
15618.108.0.0/1418.108.0.1 to 18.111.255.25418.111.255.255262,142
15718.112.0.0/1418.112.0.1 to 18.115.255.25418.115.255.255262,142
15818.116.0.0/1418.116.0.1 to 18.119.255.25418.119.255.255262,142
15918.120.0.0/1418.120.0.1 to 18.123.255.25418.123.255.255262,142
16018.124.0.0/1418.124.0.1 to 18.127.255.25418.127.255.255262,142
16118.128.0.0/1418.128.0.1 to 18.131.255.25418.131.255.255262,142
16218.132.0.0/1418.132.0.1 to 18.135.255.25418.135.255.255262,142
16318.136.0.0/1418.136.0.1 to 18.139.255.25418.139.255.255262,142
16418.140.0.0/1418.140.0.1 to 18.143.255.25418.143.255.255262,142
16518.144.0.0/1418.144.0.1 to 18.147.255.25418.147.255.255262,142
16618.148.0.0/1418.148.0.1 to 18.151.255.25418.151.255.255262,142
16718.152.0.0/1418.152.0.1 to 18.155.255.25418.155.255.255262,142
16818.156.0.0/1418.156.0.1 to 18.159.255.25418.159.255.255262,142
16918.160.0.0/1418.160.0.1 to 18.163.255.25418.163.255.255262,142
17018.164.0.0/1418.164.0.1 to 18.167.255.25418.167.255.255262,142
17118.168.0.0/1418.168.0.1 to 18.171.255.25418.171.255.255262,142
17218.172.0.0/1418.172.0.1 to 18.175.255.25418.175.255.255262,142
17318.176.0.0/1418.176.0.1 to 18.179.255.25418.179.255.255262,142
17418.180.0.0/1418.180.0.1 to 18.183.255.25418.183.255.255262,142
17518.184.0.0/1418.184.0.1 to 18.187.255.25418.187.255.255262,142
17618.188.0.0/1418.188.0.1 to 18.191.255.25418.191.255.255262,142
17718.192.0.0/1418.192.0.1 to 18.195.255.25418.195.255.255262,142
17818.196.0.0/1418.196.0.1 to 18.199.255.25418.199.255.255262,142
17918.200.0.0/1418.200.0.1 to 18.203.255.25418.203.255.255262,142
18018.204.0.0/1418.204.0.1 to 18.207.255.25418.207.255.255262,142
18118.208.0.0/1418.208.0.1 to 18.211.255.25418.211.255.255262,142
18218.212.0.0/1418.212.0.1 to 18.215.255.25418.215.255.255262,142
18318.216.0.0/1418.216.0.1 to 18.219.255.25418.219.255.255262,142
18418.220.0.0/1418.220.0.1 to 18.223.255.25418.223.255.255262,142
18518.224.0.0/1418.224.0.1 to 18.227.255.25418.227.255.255262,142
18618.228.0.0/1418.228.0.1 to 18.231.255.25418.231.255.255262,142
18718.232.0.0/1418.232.0.1 to 18.235.255.25418.235.255.255262,142
18818.236.0.0/1418.236.0.1 to 18.239.255.25418.239.255.255262,142
18918.240.0.0/1418.240.0.1 to 18.243.255.25418.243.255.255262,142
19018.244.0.0/1418.244.0.1 to 18.247.255.25418.247.255.255262,142
19118.248.0.0/1418.248.0.1 to 18.251.255.25418.251.255.255262,142
19218.252.0.0/1418.252.0.1 to 18.255.255.25418.255.255.255262,142
19319.0.0.0/1419.0.0.1 to 19.3.255.25419.3.255.255262,142
19419.4.0.0/1419.4.0.1 to 19.7.255.25419.7.255.255262,142
19519.8.0.0/1419.8.0.1 to 19.11.255.25419.11.255.255262,142
19619.12.0.0/1419.12.0.1 to 19.15.255.25419.15.255.255262,142
19719.16.0.0/1419.16.0.1 to 19.19.255.25419.19.255.255262,142
19819.20.0.0/1419.20.0.1 to 19.23.255.25419.23.255.255262,142
19919.24.0.0/1419.24.0.1 to 19.27.255.25419.27.255.255262,142
20019.28.0.0/1419.28.0.1 to 19.31.255.25419.31.255.255262,142
20119.32.0.0/1419.32.0.1 to 19.35.255.25419.35.255.255262,142
20219.36.0.0/1419.36.0.1 to 19.39.255.25419.39.255.255262,142
20319.40.0.0/1419.40.0.1 to 19.43.255.25419.43.255.255262,142
20419.44.0.0/1419.44.0.1 to 19.47.255.25419.47.255.255262,142
20519.48.0.0/1419.48.0.1 to 19.51.255.25419.51.255.255262,142
20619.52.0.0/1419.52.0.1 to 19.55.255.25419.55.255.255262,142
20719.56.0.0/1419.56.0.1 to 19.59.255.25419.59.255.255262,142
20819.60.0.0/1419.60.0.1 to 19.63.255.25419.63.255.255262,142
20919.64.0.0/1419.64.0.1 to 19.67.255.25419.67.255.255262,142
21019.68.0.0/1419.68.0.1 to 19.71.255.25419.71.255.255262,142
21119.72.0.0/1419.72.0.1 to 19.75.255.25419.75.255.255262,142
21219.76.0.0/1419.76.0.1 to 19.79.255.25419.79.255.255262,142
21319.80.0.0/1419.80.0.1 to 19.83.255.25419.83.255.255262,142
21419.84.0.0/1419.84.0.1 to 19.87.255.25419.87.255.255262,142
21519.88.0.0/1419.88.0.1 to 19.91.255.25419.91.255.255262,142
21619.92.0.0/1419.92.0.1 to 19.95.255.25419.95.255.255262,142
21719.96.0.0/1419.96.0.1 to 19.99.255.25419.99.255.255262,142
21819.100.0.0/1419.100.0.1 to 19.103.255.25419.103.255.255262,142
21919.104.0.0/1419.104.0.1 to 19.107.255.25419.107.255.255262,142
22019.108.0.0/1419.108.0.1 to 19.111.255.25419.111.255.255262,142
22119.112.0.0/1419.112.0.1 to 19.115.255.25419.115.255.255262,142
22219.116.0.0/1419.116.0.1 to 19.119.255.25419.119.255.255262,142
22319.120.0.0/1419.120.0.1 to 19.123.255.25419.123.255.255262,142
22419.124.0.0/1419.124.0.1 to 19.127.255.25419.127.255.255262,142
22519.128.0.0/1419.128.0.1 to 19.131.255.25419.131.255.255262,142
22619.132.0.0/1419.132.0.1 to 19.135.255.25419.135.255.255262,142
22719.136.0.0/1419.136.0.1 to 19.139.255.25419.139.255.255262,142
22819.140.0.0/1419.140.0.1 to 19.143.255.25419.143.255.255262,142
22919.144.0.0/1419.144.0.1 to 19.147.255.25419.147.255.255262,142
23019.148.0.0/1419.148.0.1 to 19.151.255.25419.151.255.255262,142
23119.152.0.0/1419.152.0.1 to 19.155.255.25419.155.255.255262,142
23219.156.0.0/1419.156.0.1 to 19.159.255.25419.159.255.255262,142
23319.160.0.0/1419.160.0.1 to 19.163.255.25419.163.255.255262,142
23419.164.0.0/1419.164.0.1 to 19.167.255.25419.167.255.255262,142
23519.168.0.0/1419.168.0.1 to 19.171.255.25419.171.255.255262,142
23619.172.0.0/1419.172.0.1 to 19.175.255.25419.175.255.255262,142
23719.176.0.0/1419.176.0.1 to 19.179.255.25419.179.255.255262,142
23819.180.0.0/1419.180.0.1 to 19.183.255.25419.183.255.255262,142
23919.184.0.0/1419.184.0.1 to 19.187.255.25419.187.255.255262,142
24019.188.0.0/1419.188.0.1 to 19.191.255.25419.191.255.255262,142
24119.192.0.0/1419.192.0.1 to 19.195.255.25419.195.255.255262,142
24219.196.0.0/1419.196.0.1 to 19.199.255.25419.199.255.255262,142
24319.200.0.0/1419.200.0.1 to 19.203.255.25419.203.255.255262,142
24419.204.0.0/1419.204.0.1 to 19.207.255.25419.207.255.255262,142
24519.208.0.0/1419.208.0.1 to 19.211.255.25419.211.255.255262,142
24619.212.0.0/1419.212.0.1 to 19.215.255.25419.215.255.255262,142
24719.216.0.0/1419.216.0.1 to 19.219.255.25419.219.255.255262,142
24819.220.0.0/1419.220.0.1 to 19.223.255.25419.223.255.255262,142
24919.224.0.0/1419.224.0.1 to 19.227.255.25419.227.255.255262,142
25019.228.0.0/1419.228.0.1 to 19.231.255.25419.231.255.255262,142
25119.232.0.0/1419.232.0.1 to 19.235.255.25419.235.255.255262,142
25219.236.0.0/1419.236.0.1 to 19.239.255.25419.239.255.255262,142
25319.240.0.0/1419.240.0.1 to 19.243.255.25419.243.255.255262,142
25419.244.0.0/1419.244.0.1 to 19.247.255.25419.247.255.255262,142
25519.248.0.0/1419.248.0.1 to 19.251.255.25419.251.255.255262,142
25619.252.0.0/1419.252.0.1 to 19.255.255.25419.255.255.255262,142

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.