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.

Network13.112.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
13.112.0.0
Broadcast address
13.127.255.255
First usable
13.112.0.1
Last usable
13.127.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 0D700000 · Integer 225443840 to 226492415
Reverse DNS zones
112.13.in-addr.arpa
113.13.in-addr.arpa
114.13.in-addr.arpa
115.13.in-addr.arpa
116.13.in-addr.arpa
117.13.in-addr.arpa
118.13.in-addr.arpa
119.13.in-addr.arpa
120.13.in-addr.arpa
121.13.in-addr.arpa
122.13.in-addr.arpa
123.13.in-addr.arpa
124.13.in-addr.arpa
125.13.in-addr.arpa
126.13.in-addr.arpa
127.13.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001101.01110000.00000000.0000000013.112.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00001101.01110000.00000000.0000000013.112.0.0
Broadcast00001101.01111111.11111111.1111111113.127.255.255
Split into smaller subnets/24
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

13.112.0.0/12 makes 4,096 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
113.112.0.0/2413.112.0.1 to 13.112.0.25413.112.0.255254
213.112.1.0/2413.112.1.1 to 13.112.1.25413.112.1.255254
313.112.2.0/2413.112.2.1 to 13.112.2.25413.112.2.255254
413.112.3.0/2413.112.3.1 to 13.112.3.25413.112.3.255254
513.112.4.0/2413.112.4.1 to 13.112.4.25413.112.4.255254
613.112.5.0/2413.112.5.1 to 13.112.5.25413.112.5.255254
713.112.6.0/2413.112.6.1 to 13.112.6.25413.112.6.255254
813.112.7.0/2413.112.7.1 to 13.112.7.25413.112.7.255254
913.112.8.0/2413.112.8.1 to 13.112.8.25413.112.8.255254
1013.112.9.0/2413.112.9.1 to 13.112.9.25413.112.9.255254
1113.112.10.0/2413.112.10.1 to 13.112.10.25413.112.10.255254
1213.112.11.0/2413.112.11.1 to 13.112.11.25413.112.11.255254
1313.112.12.0/2413.112.12.1 to 13.112.12.25413.112.12.255254
1413.112.13.0/2413.112.13.1 to 13.112.13.25413.112.13.255254
1513.112.14.0/2413.112.14.1 to 13.112.14.25413.112.14.255254
1613.112.15.0/2413.112.15.1 to 13.112.15.25413.112.15.255254
1713.112.16.0/2413.112.16.1 to 13.112.16.25413.112.16.255254
1813.112.17.0/2413.112.17.1 to 13.112.17.25413.112.17.255254
1913.112.18.0/2413.112.18.1 to 13.112.18.25413.112.18.255254
2013.112.19.0/2413.112.19.1 to 13.112.19.25413.112.19.255254
2113.112.20.0/2413.112.20.1 to 13.112.20.25413.112.20.255254
2213.112.21.0/2413.112.21.1 to 13.112.21.25413.112.21.255254
2313.112.22.0/2413.112.22.1 to 13.112.22.25413.112.22.255254
2413.112.23.0/2413.112.23.1 to 13.112.23.25413.112.23.255254
2513.112.24.0/2413.112.24.1 to 13.112.24.25413.112.24.255254
2613.112.25.0/2413.112.25.1 to 13.112.25.25413.112.25.255254
2713.112.26.0/2413.112.26.1 to 13.112.26.25413.112.26.255254
2813.112.27.0/2413.112.27.1 to 13.112.27.25413.112.27.255254
2913.112.28.0/2413.112.28.1 to 13.112.28.25413.112.28.255254
3013.112.29.0/2413.112.29.1 to 13.112.29.25413.112.29.255254
3113.112.30.0/2413.112.30.1 to 13.112.30.25413.112.30.255254
3213.112.31.0/2413.112.31.1 to 13.112.31.25413.112.31.255254
3313.112.32.0/2413.112.32.1 to 13.112.32.25413.112.32.255254
3413.112.33.0/2413.112.33.1 to 13.112.33.25413.112.33.255254
3513.112.34.0/2413.112.34.1 to 13.112.34.25413.112.34.255254
3613.112.35.0/2413.112.35.1 to 13.112.35.25413.112.35.255254
3713.112.36.0/2413.112.36.1 to 13.112.36.25413.112.36.255254
3813.112.37.0/2413.112.37.1 to 13.112.37.25413.112.37.255254
3913.112.38.0/2413.112.38.1 to 13.112.38.25413.112.38.255254
4013.112.39.0/2413.112.39.1 to 13.112.39.25413.112.39.255254
4113.112.40.0/2413.112.40.1 to 13.112.40.25413.112.40.255254
4213.112.41.0/2413.112.41.1 to 13.112.41.25413.112.41.255254
4313.112.42.0/2413.112.42.1 to 13.112.42.25413.112.42.255254
4413.112.43.0/2413.112.43.1 to 13.112.43.25413.112.43.255254
4513.112.44.0/2413.112.44.1 to 13.112.44.25413.112.44.255254
4613.112.45.0/2413.112.45.1 to 13.112.45.25413.112.45.255254
4713.112.46.0/2413.112.46.1 to 13.112.46.25413.112.46.255254
4813.112.47.0/2413.112.47.1 to 13.112.47.25413.112.47.255254
4913.112.48.0/2413.112.48.1 to 13.112.48.25413.112.48.255254
5013.112.49.0/2413.112.49.1 to 13.112.49.25413.112.49.255254
5113.112.50.0/2413.112.50.1 to 13.112.50.25413.112.50.255254
5213.112.51.0/2413.112.51.1 to 13.112.51.25413.112.51.255254
5313.112.52.0/2413.112.52.1 to 13.112.52.25413.112.52.255254
5413.112.53.0/2413.112.53.1 to 13.112.53.25413.112.53.255254
5513.112.54.0/2413.112.54.1 to 13.112.54.25413.112.54.255254
5613.112.55.0/2413.112.55.1 to 13.112.55.25413.112.55.255254
5713.112.56.0/2413.112.56.1 to 13.112.56.25413.112.56.255254
5813.112.57.0/2413.112.57.1 to 13.112.57.25413.112.57.255254
5913.112.58.0/2413.112.58.1 to 13.112.58.25413.112.58.255254
6013.112.59.0/2413.112.59.1 to 13.112.59.25413.112.59.255254
6113.112.60.0/2413.112.60.1 to 13.112.60.25413.112.60.255254
6213.112.61.0/2413.112.61.1 to 13.112.61.25413.112.61.255254
6313.112.62.0/2413.112.62.1 to 13.112.62.25413.112.62.255254
6413.112.63.0/2413.112.63.1 to 13.112.63.25413.112.63.255254
6513.112.64.0/2413.112.64.1 to 13.112.64.25413.112.64.255254
6613.112.65.0/2413.112.65.1 to 13.112.65.25413.112.65.255254
6713.112.66.0/2413.112.66.1 to 13.112.66.25413.112.66.255254
6813.112.67.0/2413.112.67.1 to 13.112.67.25413.112.67.255254
6913.112.68.0/2413.112.68.1 to 13.112.68.25413.112.68.255254
7013.112.69.0/2413.112.69.1 to 13.112.69.25413.112.69.255254
7113.112.70.0/2413.112.70.1 to 13.112.70.25413.112.70.255254
7213.112.71.0/2413.112.71.1 to 13.112.71.25413.112.71.255254
7313.112.72.0/2413.112.72.1 to 13.112.72.25413.112.72.255254
7413.112.73.0/2413.112.73.1 to 13.112.73.25413.112.73.255254
7513.112.74.0/2413.112.74.1 to 13.112.74.25413.112.74.255254
7613.112.75.0/2413.112.75.1 to 13.112.75.25413.112.75.255254
7713.112.76.0/2413.112.76.1 to 13.112.76.25413.112.76.255254
7813.112.77.0/2413.112.77.1 to 13.112.77.25413.112.77.255254
7913.112.78.0/2413.112.78.1 to 13.112.78.25413.112.78.255254
8013.112.79.0/2413.112.79.1 to 13.112.79.25413.112.79.255254
8113.112.80.0/2413.112.80.1 to 13.112.80.25413.112.80.255254
8213.112.81.0/2413.112.81.1 to 13.112.81.25413.112.81.255254
8313.112.82.0/2413.112.82.1 to 13.112.82.25413.112.82.255254
8413.112.83.0/2413.112.83.1 to 13.112.83.25413.112.83.255254
8513.112.84.0/2413.112.84.1 to 13.112.84.25413.112.84.255254
8613.112.85.0/2413.112.85.1 to 13.112.85.25413.112.85.255254
8713.112.86.0/2413.112.86.1 to 13.112.86.25413.112.86.255254
8813.112.87.0/2413.112.87.1 to 13.112.87.25413.112.87.255254
8913.112.88.0/2413.112.88.1 to 13.112.88.25413.112.88.255254
9013.112.89.0/2413.112.89.1 to 13.112.89.25413.112.89.255254
9113.112.90.0/2413.112.90.1 to 13.112.90.25413.112.90.255254
9213.112.91.0/2413.112.91.1 to 13.112.91.25413.112.91.255254
9313.112.92.0/2413.112.92.1 to 13.112.92.25413.112.92.255254
9413.112.93.0/2413.112.93.1 to 13.112.93.25413.112.93.255254
9513.112.94.0/2413.112.94.1 to 13.112.94.25413.112.94.255254
9613.112.95.0/2413.112.95.1 to 13.112.95.25413.112.95.255254
9713.112.96.0/2413.112.96.1 to 13.112.96.25413.112.96.255254
9813.112.97.0/2413.112.97.1 to 13.112.97.25413.112.97.255254
9913.112.98.0/2413.112.98.1 to 13.112.98.25413.112.98.255254
10013.112.99.0/2413.112.99.1 to 13.112.99.25413.112.99.255254
10113.112.100.0/2413.112.100.1 to 13.112.100.25413.112.100.255254
10213.112.101.0/2413.112.101.1 to 13.112.101.25413.112.101.255254
10313.112.102.0/2413.112.102.1 to 13.112.102.25413.112.102.255254
10413.112.103.0/2413.112.103.1 to 13.112.103.25413.112.103.255254
10513.112.104.0/2413.112.104.1 to 13.112.104.25413.112.104.255254
10613.112.105.0/2413.112.105.1 to 13.112.105.25413.112.105.255254
10713.112.106.0/2413.112.106.1 to 13.112.106.25413.112.106.255254
10813.112.107.0/2413.112.107.1 to 13.112.107.25413.112.107.255254
10913.112.108.0/2413.112.108.1 to 13.112.108.25413.112.108.255254
11013.112.109.0/2413.112.109.1 to 13.112.109.25413.112.109.255254
11113.112.110.0/2413.112.110.1 to 13.112.110.25413.112.110.255254
11213.112.111.0/2413.112.111.1 to 13.112.111.25413.112.111.255254
11313.112.112.0/2413.112.112.1 to 13.112.112.25413.112.112.255254
11413.112.113.0/2413.112.113.1 to 13.112.113.25413.112.113.255254
11513.112.114.0/2413.112.114.1 to 13.112.114.25413.112.114.255254
11613.112.115.0/2413.112.115.1 to 13.112.115.25413.112.115.255254
11713.112.116.0/2413.112.116.1 to 13.112.116.25413.112.116.255254
11813.112.117.0/2413.112.117.1 to 13.112.117.25413.112.117.255254
11913.112.118.0/2413.112.118.1 to 13.112.118.25413.112.118.255254
12013.112.119.0/2413.112.119.1 to 13.112.119.25413.112.119.255254
12113.112.120.0/2413.112.120.1 to 13.112.120.25413.112.120.255254
12213.112.121.0/2413.112.121.1 to 13.112.121.25413.112.121.255254
12313.112.122.0/2413.112.122.1 to 13.112.122.25413.112.122.255254
12413.112.123.0/2413.112.123.1 to 13.112.123.25413.112.123.255254
12513.112.124.0/2413.112.124.1 to 13.112.124.25413.112.124.255254
12613.112.125.0/2413.112.125.1 to 13.112.125.25413.112.125.255254
12713.112.126.0/2413.112.126.1 to 13.112.126.25413.112.126.255254
12813.112.127.0/2413.112.127.1 to 13.112.127.25413.112.127.255254
12913.112.128.0/2413.112.128.1 to 13.112.128.25413.112.128.255254
13013.112.129.0/2413.112.129.1 to 13.112.129.25413.112.129.255254
13113.112.130.0/2413.112.130.1 to 13.112.130.25413.112.130.255254
13213.112.131.0/2413.112.131.1 to 13.112.131.25413.112.131.255254
13313.112.132.0/2413.112.132.1 to 13.112.132.25413.112.132.255254
13413.112.133.0/2413.112.133.1 to 13.112.133.25413.112.133.255254
13513.112.134.0/2413.112.134.1 to 13.112.134.25413.112.134.255254
13613.112.135.0/2413.112.135.1 to 13.112.135.25413.112.135.255254
13713.112.136.0/2413.112.136.1 to 13.112.136.25413.112.136.255254
13813.112.137.0/2413.112.137.1 to 13.112.137.25413.112.137.255254
13913.112.138.0/2413.112.138.1 to 13.112.138.25413.112.138.255254
14013.112.139.0/2413.112.139.1 to 13.112.139.25413.112.139.255254
14113.112.140.0/2413.112.140.1 to 13.112.140.25413.112.140.255254
14213.112.141.0/2413.112.141.1 to 13.112.141.25413.112.141.255254
14313.112.142.0/2413.112.142.1 to 13.112.142.25413.112.142.255254
14413.112.143.0/2413.112.143.1 to 13.112.143.25413.112.143.255254
14513.112.144.0/2413.112.144.1 to 13.112.144.25413.112.144.255254
14613.112.145.0/2413.112.145.1 to 13.112.145.25413.112.145.255254
14713.112.146.0/2413.112.146.1 to 13.112.146.25413.112.146.255254
14813.112.147.0/2413.112.147.1 to 13.112.147.25413.112.147.255254
14913.112.148.0/2413.112.148.1 to 13.112.148.25413.112.148.255254
15013.112.149.0/2413.112.149.1 to 13.112.149.25413.112.149.255254
15113.112.150.0/2413.112.150.1 to 13.112.150.25413.112.150.255254
15213.112.151.0/2413.112.151.1 to 13.112.151.25413.112.151.255254
15313.112.152.0/2413.112.152.1 to 13.112.152.25413.112.152.255254
15413.112.153.0/2413.112.153.1 to 13.112.153.25413.112.153.255254
15513.112.154.0/2413.112.154.1 to 13.112.154.25413.112.154.255254
15613.112.155.0/2413.112.155.1 to 13.112.155.25413.112.155.255254
15713.112.156.0/2413.112.156.1 to 13.112.156.25413.112.156.255254
15813.112.157.0/2413.112.157.1 to 13.112.157.25413.112.157.255254
15913.112.158.0/2413.112.158.1 to 13.112.158.25413.112.158.255254
16013.112.159.0/2413.112.159.1 to 13.112.159.25413.112.159.255254
16113.112.160.0/2413.112.160.1 to 13.112.160.25413.112.160.255254
16213.112.161.0/2413.112.161.1 to 13.112.161.25413.112.161.255254
16313.112.162.0/2413.112.162.1 to 13.112.162.25413.112.162.255254
16413.112.163.0/2413.112.163.1 to 13.112.163.25413.112.163.255254
16513.112.164.0/2413.112.164.1 to 13.112.164.25413.112.164.255254
16613.112.165.0/2413.112.165.1 to 13.112.165.25413.112.165.255254
16713.112.166.0/2413.112.166.1 to 13.112.166.25413.112.166.255254
16813.112.167.0/2413.112.167.1 to 13.112.167.25413.112.167.255254
16913.112.168.0/2413.112.168.1 to 13.112.168.25413.112.168.255254
17013.112.169.0/2413.112.169.1 to 13.112.169.25413.112.169.255254
17113.112.170.0/2413.112.170.1 to 13.112.170.25413.112.170.255254
17213.112.171.0/2413.112.171.1 to 13.112.171.25413.112.171.255254
17313.112.172.0/2413.112.172.1 to 13.112.172.25413.112.172.255254
17413.112.173.0/2413.112.173.1 to 13.112.173.25413.112.173.255254
17513.112.174.0/2413.112.174.1 to 13.112.174.25413.112.174.255254
17613.112.175.0/2413.112.175.1 to 13.112.175.25413.112.175.255254
17713.112.176.0/2413.112.176.1 to 13.112.176.25413.112.176.255254
17813.112.177.0/2413.112.177.1 to 13.112.177.25413.112.177.255254
17913.112.178.0/2413.112.178.1 to 13.112.178.25413.112.178.255254
18013.112.179.0/2413.112.179.1 to 13.112.179.25413.112.179.255254
18113.112.180.0/2413.112.180.1 to 13.112.180.25413.112.180.255254
18213.112.181.0/2413.112.181.1 to 13.112.181.25413.112.181.255254
18313.112.182.0/2413.112.182.1 to 13.112.182.25413.112.182.255254
18413.112.183.0/2413.112.183.1 to 13.112.183.25413.112.183.255254
18513.112.184.0/2413.112.184.1 to 13.112.184.25413.112.184.255254
18613.112.185.0/2413.112.185.1 to 13.112.185.25413.112.185.255254
18713.112.186.0/2413.112.186.1 to 13.112.186.25413.112.186.255254
18813.112.187.0/2413.112.187.1 to 13.112.187.25413.112.187.255254
18913.112.188.0/2413.112.188.1 to 13.112.188.25413.112.188.255254
19013.112.189.0/2413.112.189.1 to 13.112.189.25413.112.189.255254
19113.112.190.0/2413.112.190.1 to 13.112.190.25413.112.190.255254
19213.112.191.0/2413.112.191.1 to 13.112.191.25413.112.191.255254
19313.112.192.0/2413.112.192.1 to 13.112.192.25413.112.192.255254
19413.112.193.0/2413.112.193.1 to 13.112.193.25413.112.193.255254
19513.112.194.0/2413.112.194.1 to 13.112.194.25413.112.194.255254
19613.112.195.0/2413.112.195.1 to 13.112.195.25413.112.195.255254
19713.112.196.0/2413.112.196.1 to 13.112.196.25413.112.196.255254
19813.112.197.0/2413.112.197.1 to 13.112.197.25413.112.197.255254
19913.112.198.0/2413.112.198.1 to 13.112.198.25413.112.198.255254
20013.112.199.0/2413.112.199.1 to 13.112.199.25413.112.199.255254
20113.112.200.0/2413.112.200.1 to 13.112.200.25413.112.200.255254
20213.112.201.0/2413.112.201.1 to 13.112.201.25413.112.201.255254
20313.112.202.0/2413.112.202.1 to 13.112.202.25413.112.202.255254
20413.112.203.0/2413.112.203.1 to 13.112.203.25413.112.203.255254
20513.112.204.0/2413.112.204.1 to 13.112.204.25413.112.204.255254
20613.112.205.0/2413.112.205.1 to 13.112.205.25413.112.205.255254
20713.112.206.0/2413.112.206.1 to 13.112.206.25413.112.206.255254
20813.112.207.0/2413.112.207.1 to 13.112.207.25413.112.207.255254
20913.112.208.0/2413.112.208.1 to 13.112.208.25413.112.208.255254
21013.112.209.0/2413.112.209.1 to 13.112.209.25413.112.209.255254
21113.112.210.0/2413.112.210.1 to 13.112.210.25413.112.210.255254
21213.112.211.0/2413.112.211.1 to 13.112.211.25413.112.211.255254
21313.112.212.0/2413.112.212.1 to 13.112.212.25413.112.212.255254
21413.112.213.0/2413.112.213.1 to 13.112.213.25413.112.213.255254
21513.112.214.0/2413.112.214.1 to 13.112.214.25413.112.214.255254
21613.112.215.0/2413.112.215.1 to 13.112.215.25413.112.215.255254
21713.112.216.0/2413.112.216.1 to 13.112.216.25413.112.216.255254
21813.112.217.0/2413.112.217.1 to 13.112.217.25413.112.217.255254
21913.112.218.0/2413.112.218.1 to 13.112.218.25413.112.218.255254
22013.112.219.0/2413.112.219.1 to 13.112.219.25413.112.219.255254
22113.112.220.0/2413.112.220.1 to 13.112.220.25413.112.220.255254
22213.112.221.0/2413.112.221.1 to 13.112.221.25413.112.221.255254
22313.112.222.0/2413.112.222.1 to 13.112.222.25413.112.222.255254
22413.112.223.0/2413.112.223.1 to 13.112.223.25413.112.223.255254
22513.112.224.0/2413.112.224.1 to 13.112.224.25413.112.224.255254
22613.112.225.0/2413.112.225.1 to 13.112.225.25413.112.225.255254
22713.112.226.0/2413.112.226.1 to 13.112.226.25413.112.226.255254
22813.112.227.0/2413.112.227.1 to 13.112.227.25413.112.227.255254
22913.112.228.0/2413.112.228.1 to 13.112.228.25413.112.228.255254
23013.112.229.0/2413.112.229.1 to 13.112.229.25413.112.229.255254
23113.112.230.0/2413.112.230.1 to 13.112.230.25413.112.230.255254
23213.112.231.0/2413.112.231.1 to 13.112.231.25413.112.231.255254
23313.112.232.0/2413.112.232.1 to 13.112.232.25413.112.232.255254
23413.112.233.0/2413.112.233.1 to 13.112.233.25413.112.233.255254
23513.112.234.0/2413.112.234.1 to 13.112.234.25413.112.234.255254
23613.112.235.0/2413.112.235.1 to 13.112.235.25413.112.235.255254
23713.112.236.0/2413.112.236.1 to 13.112.236.25413.112.236.255254
23813.112.237.0/2413.112.237.1 to 13.112.237.25413.112.237.255254
23913.112.238.0/2413.112.238.1 to 13.112.238.25413.112.238.255254
24013.112.239.0/2413.112.239.1 to 13.112.239.25413.112.239.255254
24113.112.240.0/2413.112.240.1 to 13.112.240.25413.112.240.255254
24213.112.241.0/2413.112.241.1 to 13.112.241.25413.112.241.255254
24313.112.242.0/2413.112.242.1 to 13.112.242.25413.112.242.255254
24413.112.243.0/2413.112.243.1 to 13.112.243.25413.112.243.255254
24513.112.244.0/2413.112.244.1 to 13.112.244.25413.112.244.255254
24613.112.245.0/2413.112.245.1 to 13.112.245.25413.112.245.255254
24713.112.246.0/2413.112.246.1 to 13.112.246.25413.112.246.255254
24813.112.247.0/2413.112.247.1 to 13.112.247.25413.112.247.255254
24913.112.248.0/2413.112.248.1 to 13.112.248.25413.112.248.255254
25013.112.249.0/2413.112.249.1 to 13.112.249.25413.112.249.255254
25113.112.250.0/2413.112.250.1 to 13.112.250.25413.112.250.255254
25213.112.251.0/2413.112.251.1 to 13.112.251.25413.112.251.255254
25313.112.252.0/2413.112.252.1 to 13.112.252.25413.112.252.255254
25413.112.253.0/2413.112.253.1 to 13.112.253.25413.112.253.255254
25513.112.254.0/2413.112.254.1 to 13.112.254.25413.112.254.255254
25613.112.255.0/2413.112.255.1 to 13.112.255.25413.112.255.255254

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.