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.

Network33.36.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
33.36.0.0
Broadcast address
33.39.255.255
First usable
33.36.0.1
Last usable
33.39.255.254
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 21240000 · Integer 556007424 to 556269567
Reverse DNS zones
36.33.in-addr.arpa
37.33.in-addr.arpa
38.33.in-addr.arpa
39.33.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
Address00100001.00100100.00000000.0000000033.36.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network00100001.00100100.00000000.0000000033.36.0.0
Broadcast00100001.00100111.11111111.1111111133.39.255.255
Split into smaller subnets/23
/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)

33.36.0.0/14 makes 512 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
133.36.0.0/2333.36.0.1 to 33.36.1.25433.36.1.255510
233.36.2.0/2333.36.2.1 to 33.36.3.25433.36.3.255510
333.36.4.0/2333.36.4.1 to 33.36.5.25433.36.5.255510
433.36.6.0/2333.36.6.1 to 33.36.7.25433.36.7.255510
533.36.8.0/2333.36.8.1 to 33.36.9.25433.36.9.255510
633.36.10.0/2333.36.10.1 to 33.36.11.25433.36.11.255510
733.36.12.0/2333.36.12.1 to 33.36.13.25433.36.13.255510
833.36.14.0/2333.36.14.1 to 33.36.15.25433.36.15.255510
933.36.16.0/2333.36.16.1 to 33.36.17.25433.36.17.255510
1033.36.18.0/2333.36.18.1 to 33.36.19.25433.36.19.255510
1133.36.20.0/2333.36.20.1 to 33.36.21.25433.36.21.255510
1233.36.22.0/2333.36.22.1 to 33.36.23.25433.36.23.255510
1333.36.24.0/2333.36.24.1 to 33.36.25.25433.36.25.255510
1433.36.26.0/2333.36.26.1 to 33.36.27.25433.36.27.255510
1533.36.28.0/2333.36.28.1 to 33.36.29.25433.36.29.255510
1633.36.30.0/2333.36.30.1 to 33.36.31.25433.36.31.255510
1733.36.32.0/2333.36.32.1 to 33.36.33.25433.36.33.255510
1833.36.34.0/2333.36.34.1 to 33.36.35.25433.36.35.255510
1933.36.36.0/2333.36.36.1 to 33.36.37.25433.36.37.255510
2033.36.38.0/2333.36.38.1 to 33.36.39.25433.36.39.255510
2133.36.40.0/2333.36.40.1 to 33.36.41.25433.36.41.255510
2233.36.42.0/2333.36.42.1 to 33.36.43.25433.36.43.255510
2333.36.44.0/2333.36.44.1 to 33.36.45.25433.36.45.255510
2433.36.46.0/2333.36.46.1 to 33.36.47.25433.36.47.255510
2533.36.48.0/2333.36.48.1 to 33.36.49.25433.36.49.255510
2633.36.50.0/2333.36.50.1 to 33.36.51.25433.36.51.255510
2733.36.52.0/2333.36.52.1 to 33.36.53.25433.36.53.255510
2833.36.54.0/2333.36.54.1 to 33.36.55.25433.36.55.255510
2933.36.56.0/2333.36.56.1 to 33.36.57.25433.36.57.255510
3033.36.58.0/2333.36.58.1 to 33.36.59.25433.36.59.255510
3133.36.60.0/2333.36.60.1 to 33.36.61.25433.36.61.255510
3233.36.62.0/2333.36.62.1 to 33.36.63.25433.36.63.255510
3333.36.64.0/2333.36.64.1 to 33.36.65.25433.36.65.255510
3433.36.66.0/2333.36.66.1 to 33.36.67.25433.36.67.255510
3533.36.68.0/2333.36.68.1 to 33.36.69.25433.36.69.255510
3633.36.70.0/2333.36.70.1 to 33.36.71.25433.36.71.255510
3733.36.72.0/2333.36.72.1 to 33.36.73.25433.36.73.255510
3833.36.74.0/2333.36.74.1 to 33.36.75.25433.36.75.255510
3933.36.76.0/2333.36.76.1 to 33.36.77.25433.36.77.255510
4033.36.78.0/2333.36.78.1 to 33.36.79.25433.36.79.255510
4133.36.80.0/2333.36.80.1 to 33.36.81.25433.36.81.255510
4233.36.82.0/2333.36.82.1 to 33.36.83.25433.36.83.255510
4333.36.84.0/2333.36.84.1 to 33.36.85.25433.36.85.255510
4433.36.86.0/2333.36.86.1 to 33.36.87.25433.36.87.255510
4533.36.88.0/2333.36.88.1 to 33.36.89.25433.36.89.255510
4633.36.90.0/2333.36.90.1 to 33.36.91.25433.36.91.255510
4733.36.92.0/2333.36.92.1 to 33.36.93.25433.36.93.255510
4833.36.94.0/2333.36.94.1 to 33.36.95.25433.36.95.255510
4933.36.96.0/2333.36.96.1 to 33.36.97.25433.36.97.255510
5033.36.98.0/2333.36.98.1 to 33.36.99.25433.36.99.255510
5133.36.100.0/2333.36.100.1 to 33.36.101.25433.36.101.255510
5233.36.102.0/2333.36.102.1 to 33.36.103.25433.36.103.255510
5333.36.104.0/2333.36.104.1 to 33.36.105.25433.36.105.255510
5433.36.106.0/2333.36.106.1 to 33.36.107.25433.36.107.255510
5533.36.108.0/2333.36.108.1 to 33.36.109.25433.36.109.255510
5633.36.110.0/2333.36.110.1 to 33.36.111.25433.36.111.255510
5733.36.112.0/2333.36.112.1 to 33.36.113.25433.36.113.255510
5833.36.114.0/2333.36.114.1 to 33.36.115.25433.36.115.255510
5933.36.116.0/2333.36.116.1 to 33.36.117.25433.36.117.255510
6033.36.118.0/2333.36.118.1 to 33.36.119.25433.36.119.255510
6133.36.120.0/2333.36.120.1 to 33.36.121.25433.36.121.255510
6233.36.122.0/2333.36.122.1 to 33.36.123.25433.36.123.255510
6333.36.124.0/2333.36.124.1 to 33.36.125.25433.36.125.255510
6433.36.126.0/2333.36.126.1 to 33.36.127.25433.36.127.255510
6533.36.128.0/2333.36.128.1 to 33.36.129.25433.36.129.255510
6633.36.130.0/2333.36.130.1 to 33.36.131.25433.36.131.255510
6733.36.132.0/2333.36.132.1 to 33.36.133.25433.36.133.255510
6833.36.134.0/2333.36.134.1 to 33.36.135.25433.36.135.255510
6933.36.136.0/2333.36.136.1 to 33.36.137.25433.36.137.255510
7033.36.138.0/2333.36.138.1 to 33.36.139.25433.36.139.255510
7133.36.140.0/2333.36.140.1 to 33.36.141.25433.36.141.255510
7233.36.142.0/2333.36.142.1 to 33.36.143.25433.36.143.255510
7333.36.144.0/2333.36.144.1 to 33.36.145.25433.36.145.255510
7433.36.146.0/2333.36.146.1 to 33.36.147.25433.36.147.255510
7533.36.148.0/2333.36.148.1 to 33.36.149.25433.36.149.255510
7633.36.150.0/2333.36.150.1 to 33.36.151.25433.36.151.255510
7733.36.152.0/2333.36.152.1 to 33.36.153.25433.36.153.255510
7833.36.154.0/2333.36.154.1 to 33.36.155.25433.36.155.255510
7933.36.156.0/2333.36.156.1 to 33.36.157.25433.36.157.255510
8033.36.158.0/2333.36.158.1 to 33.36.159.25433.36.159.255510
8133.36.160.0/2333.36.160.1 to 33.36.161.25433.36.161.255510
8233.36.162.0/2333.36.162.1 to 33.36.163.25433.36.163.255510
8333.36.164.0/2333.36.164.1 to 33.36.165.25433.36.165.255510
8433.36.166.0/2333.36.166.1 to 33.36.167.25433.36.167.255510
8533.36.168.0/2333.36.168.1 to 33.36.169.25433.36.169.255510
8633.36.170.0/2333.36.170.1 to 33.36.171.25433.36.171.255510
8733.36.172.0/2333.36.172.1 to 33.36.173.25433.36.173.255510
8833.36.174.0/2333.36.174.1 to 33.36.175.25433.36.175.255510
8933.36.176.0/2333.36.176.1 to 33.36.177.25433.36.177.255510
9033.36.178.0/2333.36.178.1 to 33.36.179.25433.36.179.255510
9133.36.180.0/2333.36.180.1 to 33.36.181.25433.36.181.255510
9233.36.182.0/2333.36.182.1 to 33.36.183.25433.36.183.255510
9333.36.184.0/2333.36.184.1 to 33.36.185.25433.36.185.255510
9433.36.186.0/2333.36.186.1 to 33.36.187.25433.36.187.255510
9533.36.188.0/2333.36.188.1 to 33.36.189.25433.36.189.255510
9633.36.190.0/2333.36.190.1 to 33.36.191.25433.36.191.255510
9733.36.192.0/2333.36.192.1 to 33.36.193.25433.36.193.255510
9833.36.194.0/2333.36.194.1 to 33.36.195.25433.36.195.255510
9933.36.196.0/2333.36.196.1 to 33.36.197.25433.36.197.255510
10033.36.198.0/2333.36.198.1 to 33.36.199.25433.36.199.255510
10133.36.200.0/2333.36.200.1 to 33.36.201.25433.36.201.255510
10233.36.202.0/2333.36.202.1 to 33.36.203.25433.36.203.255510
10333.36.204.0/2333.36.204.1 to 33.36.205.25433.36.205.255510
10433.36.206.0/2333.36.206.1 to 33.36.207.25433.36.207.255510
10533.36.208.0/2333.36.208.1 to 33.36.209.25433.36.209.255510
10633.36.210.0/2333.36.210.1 to 33.36.211.25433.36.211.255510
10733.36.212.0/2333.36.212.1 to 33.36.213.25433.36.213.255510
10833.36.214.0/2333.36.214.1 to 33.36.215.25433.36.215.255510
10933.36.216.0/2333.36.216.1 to 33.36.217.25433.36.217.255510
11033.36.218.0/2333.36.218.1 to 33.36.219.25433.36.219.255510
11133.36.220.0/2333.36.220.1 to 33.36.221.25433.36.221.255510
11233.36.222.0/2333.36.222.1 to 33.36.223.25433.36.223.255510
11333.36.224.0/2333.36.224.1 to 33.36.225.25433.36.225.255510
11433.36.226.0/2333.36.226.1 to 33.36.227.25433.36.227.255510
11533.36.228.0/2333.36.228.1 to 33.36.229.25433.36.229.255510
11633.36.230.0/2333.36.230.1 to 33.36.231.25433.36.231.255510
11733.36.232.0/2333.36.232.1 to 33.36.233.25433.36.233.255510
11833.36.234.0/2333.36.234.1 to 33.36.235.25433.36.235.255510
11933.36.236.0/2333.36.236.1 to 33.36.237.25433.36.237.255510
12033.36.238.0/2333.36.238.1 to 33.36.239.25433.36.239.255510
12133.36.240.0/2333.36.240.1 to 33.36.241.25433.36.241.255510
12233.36.242.0/2333.36.242.1 to 33.36.243.25433.36.243.255510
12333.36.244.0/2333.36.244.1 to 33.36.245.25433.36.245.255510
12433.36.246.0/2333.36.246.1 to 33.36.247.25433.36.247.255510
12533.36.248.0/2333.36.248.1 to 33.36.249.25433.36.249.255510
12633.36.250.0/2333.36.250.1 to 33.36.251.25433.36.251.255510
12733.36.252.0/2333.36.252.1 to 33.36.253.25433.36.253.255510
12833.36.254.0/2333.36.254.1 to 33.36.255.25433.36.255.255510
12933.37.0.0/2333.37.0.1 to 33.37.1.25433.37.1.255510
13033.37.2.0/2333.37.2.1 to 33.37.3.25433.37.3.255510
13133.37.4.0/2333.37.4.1 to 33.37.5.25433.37.5.255510
13233.37.6.0/2333.37.6.1 to 33.37.7.25433.37.7.255510
13333.37.8.0/2333.37.8.1 to 33.37.9.25433.37.9.255510
13433.37.10.0/2333.37.10.1 to 33.37.11.25433.37.11.255510
13533.37.12.0/2333.37.12.1 to 33.37.13.25433.37.13.255510
13633.37.14.0/2333.37.14.1 to 33.37.15.25433.37.15.255510
13733.37.16.0/2333.37.16.1 to 33.37.17.25433.37.17.255510
13833.37.18.0/2333.37.18.1 to 33.37.19.25433.37.19.255510
13933.37.20.0/2333.37.20.1 to 33.37.21.25433.37.21.255510
14033.37.22.0/2333.37.22.1 to 33.37.23.25433.37.23.255510
14133.37.24.0/2333.37.24.1 to 33.37.25.25433.37.25.255510
14233.37.26.0/2333.37.26.1 to 33.37.27.25433.37.27.255510
14333.37.28.0/2333.37.28.1 to 33.37.29.25433.37.29.255510
14433.37.30.0/2333.37.30.1 to 33.37.31.25433.37.31.255510
14533.37.32.0/2333.37.32.1 to 33.37.33.25433.37.33.255510
14633.37.34.0/2333.37.34.1 to 33.37.35.25433.37.35.255510
14733.37.36.0/2333.37.36.1 to 33.37.37.25433.37.37.255510
14833.37.38.0/2333.37.38.1 to 33.37.39.25433.37.39.255510
14933.37.40.0/2333.37.40.1 to 33.37.41.25433.37.41.255510
15033.37.42.0/2333.37.42.1 to 33.37.43.25433.37.43.255510
15133.37.44.0/2333.37.44.1 to 33.37.45.25433.37.45.255510
15233.37.46.0/2333.37.46.1 to 33.37.47.25433.37.47.255510
15333.37.48.0/2333.37.48.1 to 33.37.49.25433.37.49.255510
15433.37.50.0/2333.37.50.1 to 33.37.51.25433.37.51.255510
15533.37.52.0/2333.37.52.1 to 33.37.53.25433.37.53.255510
15633.37.54.0/2333.37.54.1 to 33.37.55.25433.37.55.255510
15733.37.56.0/2333.37.56.1 to 33.37.57.25433.37.57.255510
15833.37.58.0/2333.37.58.1 to 33.37.59.25433.37.59.255510
15933.37.60.0/2333.37.60.1 to 33.37.61.25433.37.61.255510
16033.37.62.0/2333.37.62.1 to 33.37.63.25433.37.63.255510
16133.37.64.0/2333.37.64.1 to 33.37.65.25433.37.65.255510
16233.37.66.0/2333.37.66.1 to 33.37.67.25433.37.67.255510
16333.37.68.0/2333.37.68.1 to 33.37.69.25433.37.69.255510
16433.37.70.0/2333.37.70.1 to 33.37.71.25433.37.71.255510
16533.37.72.0/2333.37.72.1 to 33.37.73.25433.37.73.255510
16633.37.74.0/2333.37.74.1 to 33.37.75.25433.37.75.255510
16733.37.76.0/2333.37.76.1 to 33.37.77.25433.37.77.255510
16833.37.78.0/2333.37.78.1 to 33.37.79.25433.37.79.255510
16933.37.80.0/2333.37.80.1 to 33.37.81.25433.37.81.255510
17033.37.82.0/2333.37.82.1 to 33.37.83.25433.37.83.255510
17133.37.84.0/2333.37.84.1 to 33.37.85.25433.37.85.255510
17233.37.86.0/2333.37.86.1 to 33.37.87.25433.37.87.255510
17333.37.88.0/2333.37.88.1 to 33.37.89.25433.37.89.255510
17433.37.90.0/2333.37.90.1 to 33.37.91.25433.37.91.255510
17533.37.92.0/2333.37.92.1 to 33.37.93.25433.37.93.255510
17633.37.94.0/2333.37.94.1 to 33.37.95.25433.37.95.255510
17733.37.96.0/2333.37.96.1 to 33.37.97.25433.37.97.255510
17833.37.98.0/2333.37.98.1 to 33.37.99.25433.37.99.255510
17933.37.100.0/2333.37.100.1 to 33.37.101.25433.37.101.255510
18033.37.102.0/2333.37.102.1 to 33.37.103.25433.37.103.255510
18133.37.104.0/2333.37.104.1 to 33.37.105.25433.37.105.255510
18233.37.106.0/2333.37.106.1 to 33.37.107.25433.37.107.255510
18333.37.108.0/2333.37.108.1 to 33.37.109.25433.37.109.255510
18433.37.110.0/2333.37.110.1 to 33.37.111.25433.37.111.255510
18533.37.112.0/2333.37.112.1 to 33.37.113.25433.37.113.255510
18633.37.114.0/2333.37.114.1 to 33.37.115.25433.37.115.255510
18733.37.116.0/2333.37.116.1 to 33.37.117.25433.37.117.255510
18833.37.118.0/2333.37.118.1 to 33.37.119.25433.37.119.255510
18933.37.120.0/2333.37.120.1 to 33.37.121.25433.37.121.255510
19033.37.122.0/2333.37.122.1 to 33.37.123.25433.37.123.255510
19133.37.124.0/2333.37.124.1 to 33.37.125.25433.37.125.255510
19233.37.126.0/2333.37.126.1 to 33.37.127.25433.37.127.255510
19333.37.128.0/2333.37.128.1 to 33.37.129.25433.37.129.255510
19433.37.130.0/2333.37.130.1 to 33.37.131.25433.37.131.255510
19533.37.132.0/2333.37.132.1 to 33.37.133.25433.37.133.255510
19633.37.134.0/2333.37.134.1 to 33.37.135.25433.37.135.255510
19733.37.136.0/2333.37.136.1 to 33.37.137.25433.37.137.255510
19833.37.138.0/2333.37.138.1 to 33.37.139.25433.37.139.255510
19933.37.140.0/2333.37.140.1 to 33.37.141.25433.37.141.255510
20033.37.142.0/2333.37.142.1 to 33.37.143.25433.37.143.255510
20133.37.144.0/2333.37.144.1 to 33.37.145.25433.37.145.255510
20233.37.146.0/2333.37.146.1 to 33.37.147.25433.37.147.255510
20333.37.148.0/2333.37.148.1 to 33.37.149.25433.37.149.255510
20433.37.150.0/2333.37.150.1 to 33.37.151.25433.37.151.255510
20533.37.152.0/2333.37.152.1 to 33.37.153.25433.37.153.255510
20633.37.154.0/2333.37.154.1 to 33.37.155.25433.37.155.255510
20733.37.156.0/2333.37.156.1 to 33.37.157.25433.37.157.255510
20833.37.158.0/2333.37.158.1 to 33.37.159.25433.37.159.255510
20933.37.160.0/2333.37.160.1 to 33.37.161.25433.37.161.255510
21033.37.162.0/2333.37.162.1 to 33.37.163.25433.37.163.255510
21133.37.164.0/2333.37.164.1 to 33.37.165.25433.37.165.255510
21233.37.166.0/2333.37.166.1 to 33.37.167.25433.37.167.255510
21333.37.168.0/2333.37.168.1 to 33.37.169.25433.37.169.255510
21433.37.170.0/2333.37.170.1 to 33.37.171.25433.37.171.255510
21533.37.172.0/2333.37.172.1 to 33.37.173.25433.37.173.255510
21633.37.174.0/2333.37.174.1 to 33.37.175.25433.37.175.255510
21733.37.176.0/2333.37.176.1 to 33.37.177.25433.37.177.255510
21833.37.178.0/2333.37.178.1 to 33.37.179.25433.37.179.255510
21933.37.180.0/2333.37.180.1 to 33.37.181.25433.37.181.255510
22033.37.182.0/2333.37.182.1 to 33.37.183.25433.37.183.255510
22133.37.184.0/2333.37.184.1 to 33.37.185.25433.37.185.255510
22233.37.186.0/2333.37.186.1 to 33.37.187.25433.37.187.255510
22333.37.188.0/2333.37.188.1 to 33.37.189.25433.37.189.255510
22433.37.190.0/2333.37.190.1 to 33.37.191.25433.37.191.255510
22533.37.192.0/2333.37.192.1 to 33.37.193.25433.37.193.255510
22633.37.194.0/2333.37.194.1 to 33.37.195.25433.37.195.255510
22733.37.196.0/2333.37.196.1 to 33.37.197.25433.37.197.255510
22833.37.198.0/2333.37.198.1 to 33.37.199.25433.37.199.255510
22933.37.200.0/2333.37.200.1 to 33.37.201.25433.37.201.255510
23033.37.202.0/2333.37.202.1 to 33.37.203.25433.37.203.255510
23133.37.204.0/2333.37.204.1 to 33.37.205.25433.37.205.255510
23233.37.206.0/2333.37.206.1 to 33.37.207.25433.37.207.255510
23333.37.208.0/2333.37.208.1 to 33.37.209.25433.37.209.255510
23433.37.210.0/2333.37.210.1 to 33.37.211.25433.37.211.255510
23533.37.212.0/2333.37.212.1 to 33.37.213.25433.37.213.255510
23633.37.214.0/2333.37.214.1 to 33.37.215.25433.37.215.255510
23733.37.216.0/2333.37.216.1 to 33.37.217.25433.37.217.255510
23833.37.218.0/2333.37.218.1 to 33.37.219.25433.37.219.255510
23933.37.220.0/2333.37.220.1 to 33.37.221.25433.37.221.255510
24033.37.222.0/2333.37.222.1 to 33.37.223.25433.37.223.255510
24133.37.224.0/2333.37.224.1 to 33.37.225.25433.37.225.255510
24233.37.226.0/2333.37.226.1 to 33.37.227.25433.37.227.255510
24333.37.228.0/2333.37.228.1 to 33.37.229.25433.37.229.255510
24433.37.230.0/2333.37.230.1 to 33.37.231.25433.37.231.255510
24533.37.232.0/2333.37.232.1 to 33.37.233.25433.37.233.255510
24633.37.234.0/2333.37.234.1 to 33.37.235.25433.37.235.255510
24733.37.236.0/2333.37.236.1 to 33.37.237.25433.37.237.255510
24833.37.238.0/2333.37.238.1 to 33.37.239.25433.37.239.255510
24933.37.240.0/2333.37.240.1 to 33.37.241.25433.37.241.255510
25033.37.242.0/2333.37.242.1 to 33.37.243.25433.37.243.255510
25133.37.244.0/2333.37.244.1 to 33.37.245.25433.37.245.255510
25233.37.246.0/2333.37.246.1 to 33.37.247.25433.37.247.255510
25333.37.248.0/2333.37.248.1 to 33.37.249.25433.37.249.255510
25433.37.250.0/2333.37.250.1 to 33.37.251.25433.37.251.255510
25533.37.252.0/2333.37.252.1 to 33.37.253.25433.37.253.255510
25633.37.254.0/2333.37.254.1 to 33.37.255.25433.37.255.255510

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.