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.

Network85.12.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
85.12.0.0
Broadcast address
85.15.255.255
First usable
85.12.0.1
Last usable
85.15.255.254
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 550C0000 · Integer 1426849792 to 1427111935
Reverse DNS zones
12.85.in-addr.arpa
13.85.in-addr.arpa
14.85.in-addr.arpa
15.85.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
Address01010101.00001100.00000000.0000000085.12.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network01010101.00001100.00000000.0000000085.12.0.0
Broadcast01010101.00001111.11111111.1111111185.15.255.255
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)

85.12.0.0/14 makes 512 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
185.12.0.0/2385.12.0.1 to 85.12.1.25485.12.1.255510
285.12.2.0/2385.12.2.1 to 85.12.3.25485.12.3.255510
385.12.4.0/2385.12.4.1 to 85.12.5.25485.12.5.255510
485.12.6.0/2385.12.6.1 to 85.12.7.25485.12.7.255510
585.12.8.0/2385.12.8.1 to 85.12.9.25485.12.9.255510
685.12.10.0/2385.12.10.1 to 85.12.11.25485.12.11.255510
785.12.12.0/2385.12.12.1 to 85.12.13.25485.12.13.255510
885.12.14.0/2385.12.14.1 to 85.12.15.25485.12.15.255510
985.12.16.0/2385.12.16.1 to 85.12.17.25485.12.17.255510
1085.12.18.0/2385.12.18.1 to 85.12.19.25485.12.19.255510
1185.12.20.0/2385.12.20.1 to 85.12.21.25485.12.21.255510
1285.12.22.0/2385.12.22.1 to 85.12.23.25485.12.23.255510
1385.12.24.0/2385.12.24.1 to 85.12.25.25485.12.25.255510
1485.12.26.0/2385.12.26.1 to 85.12.27.25485.12.27.255510
1585.12.28.0/2385.12.28.1 to 85.12.29.25485.12.29.255510
1685.12.30.0/2385.12.30.1 to 85.12.31.25485.12.31.255510
1785.12.32.0/2385.12.32.1 to 85.12.33.25485.12.33.255510
1885.12.34.0/2385.12.34.1 to 85.12.35.25485.12.35.255510
1985.12.36.0/2385.12.36.1 to 85.12.37.25485.12.37.255510
2085.12.38.0/2385.12.38.1 to 85.12.39.25485.12.39.255510
2185.12.40.0/2385.12.40.1 to 85.12.41.25485.12.41.255510
2285.12.42.0/2385.12.42.1 to 85.12.43.25485.12.43.255510
2385.12.44.0/2385.12.44.1 to 85.12.45.25485.12.45.255510
2485.12.46.0/2385.12.46.1 to 85.12.47.25485.12.47.255510
2585.12.48.0/2385.12.48.1 to 85.12.49.25485.12.49.255510
2685.12.50.0/2385.12.50.1 to 85.12.51.25485.12.51.255510
2785.12.52.0/2385.12.52.1 to 85.12.53.25485.12.53.255510
2885.12.54.0/2385.12.54.1 to 85.12.55.25485.12.55.255510
2985.12.56.0/2385.12.56.1 to 85.12.57.25485.12.57.255510
3085.12.58.0/2385.12.58.1 to 85.12.59.25485.12.59.255510
3185.12.60.0/2385.12.60.1 to 85.12.61.25485.12.61.255510
3285.12.62.0/2385.12.62.1 to 85.12.63.25485.12.63.255510
3385.12.64.0/2385.12.64.1 to 85.12.65.25485.12.65.255510
3485.12.66.0/2385.12.66.1 to 85.12.67.25485.12.67.255510
3585.12.68.0/2385.12.68.1 to 85.12.69.25485.12.69.255510
3685.12.70.0/2385.12.70.1 to 85.12.71.25485.12.71.255510
3785.12.72.0/2385.12.72.1 to 85.12.73.25485.12.73.255510
3885.12.74.0/2385.12.74.1 to 85.12.75.25485.12.75.255510
3985.12.76.0/2385.12.76.1 to 85.12.77.25485.12.77.255510
4085.12.78.0/2385.12.78.1 to 85.12.79.25485.12.79.255510
4185.12.80.0/2385.12.80.1 to 85.12.81.25485.12.81.255510
4285.12.82.0/2385.12.82.1 to 85.12.83.25485.12.83.255510
4385.12.84.0/2385.12.84.1 to 85.12.85.25485.12.85.255510
4485.12.86.0/2385.12.86.1 to 85.12.87.25485.12.87.255510
4585.12.88.0/2385.12.88.1 to 85.12.89.25485.12.89.255510
4685.12.90.0/2385.12.90.1 to 85.12.91.25485.12.91.255510
4785.12.92.0/2385.12.92.1 to 85.12.93.25485.12.93.255510
4885.12.94.0/2385.12.94.1 to 85.12.95.25485.12.95.255510
4985.12.96.0/2385.12.96.1 to 85.12.97.25485.12.97.255510
5085.12.98.0/2385.12.98.1 to 85.12.99.25485.12.99.255510
5185.12.100.0/2385.12.100.1 to 85.12.101.25485.12.101.255510
5285.12.102.0/2385.12.102.1 to 85.12.103.25485.12.103.255510
5385.12.104.0/2385.12.104.1 to 85.12.105.25485.12.105.255510
5485.12.106.0/2385.12.106.1 to 85.12.107.25485.12.107.255510
5585.12.108.0/2385.12.108.1 to 85.12.109.25485.12.109.255510
5685.12.110.0/2385.12.110.1 to 85.12.111.25485.12.111.255510
5785.12.112.0/2385.12.112.1 to 85.12.113.25485.12.113.255510
5885.12.114.0/2385.12.114.1 to 85.12.115.25485.12.115.255510
5985.12.116.0/2385.12.116.1 to 85.12.117.25485.12.117.255510
6085.12.118.0/2385.12.118.1 to 85.12.119.25485.12.119.255510
6185.12.120.0/2385.12.120.1 to 85.12.121.25485.12.121.255510
6285.12.122.0/2385.12.122.1 to 85.12.123.25485.12.123.255510
6385.12.124.0/2385.12.124.1 to 85.12.125.25485.12.125.255510
6485.12.126.0/2385.12.126.1 to 85.12.127.25485.12.127.255510
6585.12.128.0/2385.12.128.1 to 85.12.129.25485.12.129.255510
6685.12.130.0/2385.12.130.1 to 85.12.131.25485.12.131.255510
6785.12.132.0/2385.12.132.1 to 85.12.133.25485.12.133.255510
6885.12.134.0/2385.12.134.1 to 85.12.135.25485.12.135.255510
6985.12.136.0/2385.12.136.1 to 85.12.137.25485.12.137.255510
7085.12.138.0/2385.12.138.1 to 85.12.139.25485.12.139.255510
7185.12.140.0/2385.12.140.1 to 85.12.141.25485.12.141.255510
7285.12.142.0/2385.12.142.1 to 85.12.143.25485.12.143.255510
7385.12.144.0/2385.12.144.1 to 85.12.145.25485.12.145.255510
7485.12.146.0/2385.12.146.1 to 85.12.147.25485.12.147.255510
7585.12.148.0/2385.12.148.1 to 85.12.149.25485.12.149.255510
7685.12.150.0/2385.12.150.1 to 85.12.151.25485.12.151.255510
7785.12.152.0/2385.12.152.1 to 85.12.153.25485.12.153.255510
7885.12.154.0/2385.12.154.1 to 85.12.155.25485.12.155.255510
7985.12.156.0/2385.12.156.1 to 85.12.157.25485.12.157.255510
8085.12.158.0/2385.12.158.1 to 85.12.159.25485.12.159.255510
8185.12.160.0/2385.12.160.1 to 85.12.161.25485.12.161.255510
8285.12.162.0/2385.12.162.1 to 85.12.163.25485.12.163.255510
8385.12.164.0/2385.12.164.1 to 85.12.165.25485.12.165.255510
8485.12.166.0/2385.12.166.1 to 85.12.167.25485.12.167.255510
8585.12.168.0/2385.12.168.1 to 85.12.169.25485.12.169.255510
8685.12.170.0/2385.12.170.1 to 85.12.171.25485.12.171.255510
8785.12.172.0/2385.12.172.1 to 85.12.173.25485.12.173.255510
8885.12.174.0/2385.12.174.1 to 85.12.175.25485.12.175.255510
8985.12.176.0/2385.12.176.1 to 85.12.177.25485.12.177.255510
9085.12.178.0/2385.12.178.1 to 85.12.179.25485.12.179.255510
9185.12.180.0/2385.12.180.1 to 85.12.181.25485.12.181.255510
9285.12.182.0/2385.12.182.1 to 85.12.183.25485.12.183.255510
9385.12.184.0/2385.12.184.1 to 85.12.185.25485.12.185.255510
9485.12.186.0/2385.12.186.1 to 85.12.187.25485.12.187.255510
9585.12.188.0/2385.12.188.1 to 85.12.189.25485.12.189.255510
9685.12.190.0/2385.12.190.1 to 85.12.191.25485.12.191.255510
9785.12.192.0/2385.12.192.1 to 85.12.193.25485.12.193.255510
9885.12.194.0/2385.12.194.1 to 85.12.195.25485.12.195.255510
9985.12.196.0/2385.12.196.1 to 85.12.197.25485.12.197.255510
10085.12.198.0/2385.12.198.1 to 85.12.199.25485.12.199.255510
10185.12.200.0/2385.12.200.1 to 85.12.201.25485.12.201.255510
10285.12.202.0/2385.12.202.1 to 85.12.203.25485.12.203.255510
10385.12.204.0/2385.12.204.1 to 85.12.205.25485.12.205.255510
10485.12.206.0/2385.12.206.1 to 85.12.207.25485.12.207.255510
10585.12.208.0/2385.12.208.1 to 85.12.209.25485.12.209.255510
10685.12.210.0/2385.12.210.1 to 85.12.211.25485.12.211.255510
10785.12.212.0/2385.12.212.1 to 85.12.213.25485.12.213.255510
10885.12.214.0/2385.12.214.1 to 85.12.215.25485.12.215.255510
10985.12.216.0/2385.12.216.1 to 85.12.217.25485.12.217.255510
11085.12.218.0/2385.12.218.1 to 85.12.219.25485.12.219.255510
11185.12.220.0/2385.12.220.1 to 85.12.221.25485.12.221.255510
11285.12.222.0/2385.12.222.1 to 85.12.223.25485.12.223.255510
11385.12.224.0/2385.12.224.1 to 85.12.225.25485.12.225.255510
11485.12.226.0/2385.12.226.1 to 85.12.227.25485.12.227.255510
11585.12.228.0/2385.12.228.1 to 85.12.229.25485.12.229.255510
11685.12.230.0/2385.12.230.1 to 85.12.231.25485.12.231.255510
11785.12.232.0/2385.12.232.1 to 85.12.233.25485.12.233.255510
11885.12.234.0/2385.12.234.1 to 85.12.235.25485.12.235.255510
11985.12.236.0/2385.12.236.1 to 85.12.237.25485.12.237.255510
12085.12.238.0/2385.12.238.1 to 85.12.239.25485.12.239.255510
12185.12.240.0/2385.12.240.1 to 85.12.241.25485.12.241.255510
12285.12.242.0/2385.12.242.1 to 85.12.243.25485.12.243.255510
12385.12.244.0/2385.12.244.1 to 85.12.245.25485.12.245.255510
12485.12.246.0/2385.12.246.1 to 85.12.247.25485.12.247.255510
12585.12.248.0/2385.12.248.1 to 85.12.249.25485.12.249.255510
12685.12.250.0/2385.12.250.1 to 85.12.251.25485.12.251.255510
12785.12.252.0/2385.12.252.1 to 85.12.253.25485.12.253.255510
12885.12.254.0/2385.12.254.1 to 85.12.255.25485.12.255.255510
12985.13.0.0/2385.13.0.1 to 85.13.1.25485.13.1.255510
13085.13.2.0/2385.13.2.1 to 85.13.3.25485.13.3.255510
13185.13.4.0/2385.13.4.1 to 85.13.5.25485.13.5.255510
13285.13.6.0/2385.13.6.1 to 85.13.7.25485.13.7.255510
13385.13.8.0/2385.13.8.1 to 85.13.9.25485.13.9.255510
13485.13.10.0/2385.13.10.1 to 85.13.11.25485.13.11.255510
13585.13.12.0/2385.13.12.1 to 85.13.13.25485.13.13.255510
13685.13.14.0/2385.13.14.1 to 85.13.15.25485.13.15.255510
13785.13.16.0/2385.13.16.1 to 85.13.17.25485.13.17.255510
13885.13.18.0/2385.13.18.1 to 85.13.19.25485.13.19.255510
13985.13.20.0/2385.13.20.1 to 85.13.21.25485.13.21.255510
14085.13.22.0/2385.13.22.1 to 85.13.23.25485.13.23.255510
14185.13.24.0/2385.13.24.1 to 85.13.25.25485.13.25.255510
14285.13.26.0/2385.13.26.1 to 85.13.27.25485.13.27.255510
14385.13.28.0/2385.13.28.1 to 85.13.29.25485.13.29.255510
14485.13.30.0/2385.13.30.1 to 85.13.31.25485.13.31.255510
14585.13.32.0/2385.13.32.1 to 85.13.33.25485.13.33.255510
14685.13.34.0/2385.13.34.1 to 85.13.35.25485.13.35.255510
14785.13.36.0/2385.13.36.1 to 85.13.37.25485.13.37.255510
14885.13.38.0/2385.13.38.1 to 85.13.39.25485.13.39.255510
14985.13.40.0/2385.13.40.1 to 85.13.41.25485.13.41.255510
15085.13.42.0/2385.13.42.1 to 85.13.43.25485.13.43.255510
15185.13.44.0/2385.13.44.1 to 85.13.45.25485.13.45.255510
15285.13.46.0/2385.13.46.1 to 85.13.47.25485.13.47.255510
15385.13.48.0/2385.13.48.1 to 85.13.49.25485.13.49.255510
15485.13.50.0/2385.13.50.1 to 85.13.51.25485.13.51.255510
15585.13.52.0/2385.13.52.1 to 85.13.53.25485.13.53.255510
15685.13.54.0/2385.13.54.1 to 85.13.55.25485.13.55.255510
15785.13.56.0/2385.13.56.1 to 85.13.57.25485.13.57.255510
15885.13.58.0/2385.13.58.1 to 85.13.59.25485.13.59.255510
15985.13.60.0/2385.13.60.1 to 85.13.61.25485.13.61.255510
16085.13.62.0/2385.13.62.1 to 85.13.63.25485.13.63.255510
16185.13.64.0/2385.13.64.1 to 85.13.65.25485.13.65.255510
16285.13.66.0/2385.13.66.1 to 85.13.67.25485.13.67.255510
16385.13.68.0/2385.13.68.1 to 85.13.69.25485.13.69.255510
16485.13.70.0/2385.13.70.1 to 85.13.71.25485.13.71.255510
16585.13.72.0/2385.13.72.1 to 85.13.73.25485.13.73.255510
16685.13.74.0/2385.13.74.1 to 85.13.75.25485.13.75.255510
16785.13.76.0/2385.13.76.1 to 85.13.77.25485.13.77.255510
16885.13.78.0/2385.13.78.1 to 85.13.79.25485.13.79.255510
16985.13.80.0/2385.13.80.1 to 85.13.81.25485.13.81.255510
17085.13.82.0/2385.13.82.1 to 85.13.83.25485.13.83.255510
17185.13.84.0/2385.13.84.1 to 85.13.85.25485.13.85.255510
17285.13.86.0/2385.13.86.1 to 85.13.87.25485.13.87.255510
17385.13.88.0/2385.13.88.1 to 85.13.89.25485.13.89.255510
17485.13.90.0/2385.13.90.1 to 85.13.91.25485.13.91.255510
17585.13.92.0/2385.13.92.1 to 85.13.93.25485.13.93.255510
17685.13.94.0/2385.13.94.1 to 85.13.95.25485.13.95.255510
17785.13.96.0/2385.13.96.1 to 85.13.97.25485.13.97.255510
17885.13.98.0/2385.13.98.1 to 85.13.99.25485.13.99.255510
17985.13.100.0/2385.13.100.1 to 85.13.101.25485.13.101.255510
18085.13.102.0/2385.13.102.1 to 85.13.103.25485.13.103.255510
18185.13.104.0/2385.13.104.1 to 85.13.105.25485.13.105.255510
18285.13.106.0/2385.13.106.1 to 85.13.107.25485.13.107.255510
18385.13.108.0/2385.13.108.1 to 85.13.109.25485.13.109.255510
18485.13.110.0/2385.13.110.1 to 85.13.111.25485.13.111.255510
18585.13.112.0/2385.13.112.1 to 85.13.113.25485.13.113.255510
18685.13.114.0/2385.13.114.1 to 85.13.115.25485.13.115.255510
18785.13.116.0/2385.13.116.1 to 85.13.117.25485.13.117.255510
18885.13.118.0/2385.13.118.1 to 85.13.119.25485.13.119.255510
18985.13.120.0/2385.13.120.1 to 85.13.121.25485.13.121.255510
19085.13.122.0/2385.13.122.1 to 85.13.123.25485.13.123.255510
19185.13.124.0/2385.13.124.1 to 85.13.125.25485.13.125.255510
19285.13.126.0/2385.13.126.1 to 85.13.127.25485.13.127.255510
19385.13.128.0/2385.13.128.1 to 85.13.129.25485.13.129.255510
19485.13.130.0/2385.13.130.1 to 85.13.131.25485.13.131.255510
19585.13.132.0/2385.13.132.1 to 85.13.133.25485.13.133.255510
19685.13.134.0/2385.13.134.1 to 85.13.135.25485.13.135.255510
19785.13.136.0/2385.13.136.1 to 85.13.137.25485.13.137.255510
19885.13.138.0/2385.13.138.1 to 85.13.139.25485.13.139.255510
19985.13.140.0/2385.13.140.1 to 85.13.141.25485.13.141.255510
20085.13.142.0/2385.13.142.1 to 85.13.143.25485.13.143.255510
20185.13.144.0/2385.13.144.1 to 85.13.145.25485.13.145.255510
20285.13.146.0/2385.13.146.1 to 85.13.147.25485.13.147.255510
20385.13.148.0/2385.13.148.1 to 85.13.149.25485.13.149.255510
20485.13.150.0/2385.13.150.1 to 85.13.151.25485.13.151.255510
20585.13.152.0/2385.13.152.1 to 85.13.153.25485.13.153.255510
20685.13.154.0/2385.13.154.1 to 85.13.155.25485.13.155.255510
20785.13.156.0/2385.13.156.1 to 85.13.157.25485.13.157.255510
20885.13.158.0/2385.13.158.1 to 85.13.159.25485.13.159.255510
20985.13.160.0/2385.13.160.1 to 85.13.161.25485.13.161.255510
21085.13.162.0/2385.13.162.1 to 85.13.163.25485.13.163.255510
21185.13.164.0/2385.13.164.1 to 85.13.165.25485.13.165.255510
21285.13.166.0/2385.13.166.1 to 85.13.167.25485.13.167.255510
21385.13.168.0/2385.13.168.1 to 85.13.169.25485.13.169.255510
21485.13.170.0/2385.13.170.1 to 85.13.171.25485.13.171.255510
21585.13.172.0/2385.13.172.1 to 85.13.173.25485.13.173.255510
21685.13.174.0/2385.13.174.1 to 85.13.175.25485.13.175.255510
21785.13.176.0/2385.13.176.1 to 85.13.177.25485.13.177.255510
21885.13.178.0/2385.13.178.1 to 85.13.179.25485.13.179.255510
21985.13.180.0/2385.13.180.1 to 85.13.181.25485.13.181.255510
22085.13.182.0/2385.13.182.1 to 85.13.183.25485.13.183.255510
22185.13.184.0/2385.13.184.1 to 85.13.185.25485.13.185.255510
22285.13.186.0/2385.13.186.1 to 85.13.187.25485.13.187.255510
22385.13.188.0/2385.13.188.1 to 85.13.189.25485.13.189.255510
22485.13.190.0/2385.13.190.1 to 85.13.191.25485.13.191.255510
22585.13.192.0/2385.13.192.1 to 85.13.193.25485.13.193.255510
22685.13.194.0/2385.13.194.1 to 85.13.195.25485.13.195.255510
22785.13.196.0/2385.13.196.1 to 85.13.197.25485.13.197.255510
22885.13.198.0/2385.13.198.1 to 85.13.199.25485.13.199.255510
22985.13.200.0/2385.13.200.1 to 85.13.201.25485.13.201.255510
23085.13.202.0/2385.13.202.1 to 85.13.203.25485.13.203.255510
23185.13.204.0/2385.13.204.1 to 85.13.205.25485.13.205.255510
23285.13.206.0/2385.13.206.1 to 85.13.207.25485.13.207.255510
23385.13.208.0/2385.13.208.1 to 85.13.209.25485.13.209.255510
23485.13.210.0/2385.13.210.1 to 85.13.211.25485.13.211.255510
23585.13.212.0/2385.13.212.1 to 85.13.213.25485.13.213.255510
23685.13.214.0/2385.13.214.1 to 85.13.215.25485.13.215.255510
23785.13.216.0/2385.13.216.1 to 85.13.217.25485.13.217.255510
23885.13.218.0/2385.13.218.1 to 85.13.219.25485.13.219.255510
23985.13.220.0/2385.13.220.1 to 85.13.221.25485.13.221.255510
24085.13.222.0/2385.13.222.1 to 85.13.223.25485.13.223.255510
24185.13.224.0/2385.13.224.1 to 85.13.225.25485.13.225.255510
24285.13.226.0/2385.13.226.1 to 85.13.227.25485.13.227.255510
24385.13.228.0/2385.13.228.1 to 85.13.229.25485.13.229.255510
24485.13.230.0/2385.13.230.1 to 85.13.231.25485.13.231.255510
24585.13.232.0/2385.13.232.1 to 85.13.233.25485.13.233.255510
24685.13.234.0/2385.13.234.1 to 85.13.235.25485.13.235.255510
24785.13.236.0/2385.13.236.1 to 85.13.237.25485.13.237.255510
24885.13.238.0/2385.13.238.1 to 85.13.239.25485.13.239.255510
24985.13.240.0/2385.13.240.1 to 85.13.241.25485.13.241.255510
25085.13.242.0/2385.13.242.1 to 85.13.243.25485.13.243.255510
25185.13.244.0/2385.13.244.1 to 85.13.245.25485.13.245.255510
25285.13.246.0/2385.13.246.1 to 85.13.247.25485.13.247.255510
25385.13.248.0/2385.13.248.1 to 85.13.249.25485.13.249.255510
25485.13.250.0/2385.13.250.1 to 85.13.251.25485.13.251.255510
25585.13.252.0/2385.13.252.1 to 85.13.253.25485.13.253.255510
25685.13.254.0/2385.13.254.1 to 85.13.255.25485.13.255.255510

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.