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.

Network13.224.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
13.224.0.0
Broadcast address
13.255.255.255
First usable
13.224.0.1
Last usable
13.255.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 0DE00000 · Integer 232783872 to 234881023
Reverse DNS zones
224.13.in-addr.arpa
225.13.in-addr.arpa
226.13.in-addr.arpa
227.13.in-addr.arpa
228.13.in-addr.arpa
229.13.in-addr.arpa
230.13.in-addr.arpa
231.13.in-addr.arpa
232.13.in-addr.arpa
233.13.in-addr.arpa
234.13.in-addr.arpa
235.13.in-addr.arpa
236.13.in-addr.arpa
237.13.in-addr.arpa
238.13.in-addr.arpa
239.13.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001101.11100000.00000000.0000000013.224.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00001101.11100000.00000000.0000000013.224.0.0
Broadcast00001101.11111111.11111111.1111111113.255.255.255
Split into smaller subnets/19
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

13.224.0.0/11 makes 256 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
113.224.0.0/1913.224.0.1 to 13.224.31.25413.224.31.2558,190
213.224.32.0/1913.224.32.1 to 13.224.63.25413.224.63.2558,190
313.224.64.0/1913.224.64.1 to 13.224.95.25413.224.95.2558,190
413.224.96.0/1913.224.96.1 to 13.224.127.25413.224.127.2558,190
513.224.128.0/1913.224.128.1 to 13.224.159.25413.224.159.2558,190
613.224.160.0/1913.224.160.1 to 13.224.191.25413.224.191.2558,190
713.224.192.0/1913.224.192.1 to 13.224.223.25413.224.223.2558,190
813.224.224.0/1913.224.224.1 to 13.224.255.25413.224.255.2558,190
913.225.0.0/1913.225.0.1 to 13.225.31.25413.225.31.2558,190
1013.225.32.0/1913.225.32.1 to 13.225.63.25413.225.63.2558,190
1113.225.64.0/1913.225.64.1 to 13.225.95.25413.225.95.2558,190
1213.225.96.0/1913.225.96.1 to 13.225.127.25413.225.127.2558,190
1313.225.128.0/1913.225.128.1 to 13.225.159.25413.225.159.2558,190
1413.225.160.0/1913.225.160.1 to 13.225.191.25413.225.191.2558,190
1513.225.192.0/1913.225.192.1 to 13.225.223.25413.225.223.2558,190
1613.225.224.0/1913.225.224.1 to 13.225.255.25413.225.255.2558,190
1713.226.0.0/1913.226.0.1 to 13.226.31.25413.226.31.2558,190
1813.226.32.0/1913.226.32.1 to 13.226.63.25413.226.63.2558,190
1913.226.64.0/1913.226.64.1 to 13.226.95.25413.226.95.2558,190
2013.226.96.0/1913.226.96.1 to 13.226.127.25413.226.127.2558,190
2113.226.128.0/1913.226.128.1 to 13.226.159.25413.226.159.2558,190
2213.226.160.0/1913.226.160.1 to 13.226.191.25413.226.191.2558,190
2313.226.192.0/1913.226.192.1 to 13.226.223.25413.226.223.2558,190
2413.226.224.0/1913.226.224.1 to 13.226.255.25413.226.255.2558,190
2513.227.0.0/1913.227.0.1 to 13.227.31.25413.227.31.2558,190
2613.227.32.0/1913.227.32.1 to 13.227.63.25413.227.63.2558,190
2713.227.64.0/1913.227.64.1 to 13.227.95.25413.227.95.2558,190
2813.227.96.0/1913.227.96.1 to 13.227.127.25413.227.127.2558,190
2913.227.128.0/1913.227.128.1 to 13.227.159.25413.227.159.2558,190
3013.227.160.0/1913.227.160.1 to 13.227.191.25413.227.191.2558,190
3113.227.192.0/1913.227.192.1 to 13.227.223.25413.227.223.2558,190
3213.227.224.0/1913.227.224.1 to 13.227.255.25413.227.255.2558,190
3313.228.0.0/1913.228.0.1 to 13.228.31.25413.228.31.2558,190
3413.228.32.0/1913.228.32.1 to 13.228.63.25413.228.63.2558,190
3513.228.64.0/1913.228.64.1 to 13.228.95.25413.228.95.2558,190
3613.228.96.0/1913.228.96.1 to 13.228.127.25413.228.127.2558,190
3713.228.128.0/1913.228.128.1 to 13.228.159.25413.228.159.2558,190
3813.228.160.0/1913.228.160.1 to 13.228.191.25413.228.191.2558,190
3913.228.192.0/1913.228.192.1 to 13.228.223.25413.228.223.2558,190
4013.228.224.0/1913.228.224.1 to 13.228.255.25413.228.255.2558,190
4113.229.0.0/1913.229.0.1 to 13.229.31.25413.229.31.2558,190
4213.229.32.0/1913.229.32.1 to 13.229.63.25413.229.63.2558,190
4313.229.64.0/1913.229.64.1 to 13.229.95.25413.229.95.2558,190
4413.229.96.0/1913.229.96.1 to 13.229.127.25413.229.127.2558,190
4513.229.128.0/1913.229.128.1 to 13.229.159.25413.229.159.2558,190
4613.229.160.0/1913.229.160.1 to 13.229.191.25413.229.191.2558,190
4713.229.192.0/1913.229.192.1 to 13.229.223.25413.229.223.2558,190
4813.229.224.0/1913.229.224.1 to 13.229.255.25413.229.255.2558,190
4913.230.0.0/1913.230.0.1 to 13.230.31.25413.230.31.2558,190
5013.230.32.0/1913.230.32.1 to 13.230.63.25413.230.63.2558,190
5113.230.64.0/1913.230.64.1 to 13.230.95.25413.230.95.2558,190
5213.230.96.0/1913.230.96.1 to 13.230.127.25413.230.127.2558,190
5313.230.128.0/1913.230.128.1 to 13.230.159.25413.230.159.2558,190
5413.230.160.0/1913.230.160.1 to 13.230.191.25413.230.191.2558,190
5513.230.192.0/1913.230.192.1 to 13.230.223.25413.230.223.2558,190
5613.230.224.0/1913.230.224.1 to 13.230.255.25413.230.255.2558,190
5713.231.0.0/1913.231.0.1 to 13.231.31.25413.231.31.2558,190
5813.231.32.0/1913.231.32.1 to 13.231.63.25413.231.63.2558,190
5913.231.64.0/1913.231.64.1 to 13.231.95.25413.231.95.2558,190
6013.231.96.0/1913.231.96.1 to 13.231.127.25413.231.127.2558,190
6113.231.128.0/1913.231.128.1 to 13.231.159.25413.231.159.2558,190
6213.231.160.0/1913.231.160.1 to 13.231.191.25413.231.191.2558,190
6313.231.192.0/1913.231.192.1 to 13.231.223.25413.231.223.2558,190
6413.231.224.0/1913.231.224.1 to 13.231.255.25413.231.255.2558,190
6513.232.0.0/1913.232.0.1 to 13.232.31.25413.232.31.2558,190
6613.232.32.0/1913.232.32.1 to 13.232.63.25413.232.63.2558,190
6713.232.64.0/1913.232.64.1 to 13.232.95.25413.232.95.2558,190
6813.232.96.0/1913.232.96.1 to 13.232.127.25413.232.127.2558,190
6913.232.128.0/1913.232.128.1 to 13.232.159.25413.232.159.2558,190
7013.232.160.0/1913.232.160.1 to 13.232.191.25413.232.191.2558,190
7113.232.192.0/1913.232.192.1 to 13.232.223.25413.232.223.2558,190
7213.232.224.0/1913.232.224.1 to 13.232.255.25413.232.255.2558,190
7313.233.0.0/1913.233.0.1 to 13.233.31.25413.233.31.2558,190
7413.233.32.0/1913.233.32.1 to 13.233.63.25413.233.63.2558,190
7513.233.64.0/1913.233.64.1 to 13.233.95.25413.233.95.2558,190
7613.233.96.0/1913.233.96.1 to 13.233.127.25413.233.127.2558,190
7713.233.128.0/1913.233.128.1 to 13.233.159.25413.233.159.2558,190
7813.233.160.0/1913.233.160.1 to 13.233.191.25413.233.191.2558,190
7913.233.192.0/1913.233.192.1 to 13.233.223.25413.233.223.2558,190
8013.233.224.0/1913.233.224.1 to 13.233.255.25413.233.255.2558,190
8113.234.0.0/1913.234.0.1 to 13.234.31.25413.234.31.2558,190
8213.234.32.0/1913.234.32.1 to 13.234.63.25413.234.63.2558,190
8313.234.64.0/1913.234.64.1 to 13.234.95.25413.234.95.2558,190
8413.234.96.0/1913.234.96.1 to 13.234.127.25413.234.127.2558,190
8513.234.128.0/1913.234.128.1 to 13.234.159.25413.234.159.2558,190
8613.234.160.0/1913.234.160.1 to 13.234.191.25413.234.191.2558,190
8713.234.192.0/1913.234.192.1 to 13.234.223.25413.234.223.2558,190
8813.234.224.0/1913.234.224.1 to 13.234.255.25413.234.255.2558,190
8913.235.0.0/1913.235.0.1 to 13.235.31.25413.235.31.2558,190
9013.235.32.0/1913.235.32.1 to 13.235.63.25413.235.63.2558,190
9113.235.64.0/1913.235.64.1 to 13.235.95.25413.235.95.2558,190
9213.235.96.0/1913.235.96.1 to 13.235.127.25413.235.127.2558,190
9313.235.128.0/1913.235.128.1 to 13.235.159.25413.235.159.2558,190
9413.235.160.0/1913.235.160.1 to 13.235.191.25413.235.191.2558,190
9513.235.192.0/1913.235.192.1 to 13.235.223.25413.235.223.2558,190
9613.235.224.0/1913.235.224.1 to 13.235.255.25413.235.255.2558,190
9713.236.0.0/1913.236.0.1 to 13.236.31.25413.236.31.2558,190
9813.236.32.0/1913.236.32.1 to 13.236.63.25413.236.63.2558,190
9913.236.64.0/1913.236.64.1 to 13.236.95.25413.236.95.2558,190
10013.236.96.0/1913.236.96.1 to 13.236.127.25413.236.127.2558,190
10113.236.128.0/1913.236.128.1 to 13.236.159.25413.236.159.2558,190
10213.236.160.0/1913.236.160.1 to 13.236.191.25413.236.191.2558,190
10313.236.192.0/1913.236.192.1 to 13.236.223.25413.236.223.2558,190
10413.236.224.0/1913.236.224.1 to 13.236.255.25413.236.255.2558,190
10513.237.0.0/1913.237.0.1 to 13.237.31.25413.237.31.2558,190
10613.237.32.0/1913.237.32.1 to 13.237.63.25413.237.63.2558,190
10713.237.64.0/1913.237.64.1 to 13.237.95.25413.237.95.2558,190
10813.237.96.0/1913.237.96.1 to 13.237.127.25413.237.127.2558,190
10913.237.128.0/1913.237.128.1 to 13.237.159.25413.237.159.2558,190
11013.237.160.0/1913.237.160.1 to 13.237.191.25413.237.191.2558,190
11113.237.192.0/1913.237.192.1 to 13.237.223.25413.237.223.2558,190
11213.237.224.0/1913.237.224.1 to 13.237.255.25413.237.255.2558,190
11313.238.0.0/1913.238.0.1 to 13.238.31.25413.238.31.2558,190
11413.238.32.0/1913.238.32.1 to 13.238.63.25413.238.63.2558,190
11513.238.64.0/1913.238.64.1 to 13.238.95.25413.238.95.2558,190
11613.238.96.0/1913.238.96.1 to 13.238.127.25413.238.127.2558,190
11713.238.128.0/1913.238.128.1 to 13.238.159.25413.238.159.2558,190
11813.238.160.0/1913.238.160.1 to 13.238.191.25413.238.191.2558,190
11913.238.192.0/1913.238.192.1 to 13.238.223.25413.238.223.2558,190
12013.238.224.0/1913.238.224.1 to 13.238.255.25413.238.255.2558,190
12113.239.0.0/1913.239.0.1 to 13.239.31.25413.239.31.2558,190
12213.239.32.0/1913.239.32.1 to 13.239.63.25413.239.63.2558,190
12313.239.64.0/1913.239.64.1 to 13.239.95.25413.239.95.2558,190
12413.239.96.0/1913.239.96.1 to 13.239.127.25413.239.127.2558,190
12513.239.128.0/1913.239.128.1 to 13.239.159.25413.239.159.2558,190
12613.239.160.0/1913.239.160.1 to 13.239.191.25413.239.191.2558,190
12713.239.192.0/1913.239.192.1 to 13.239.223.25413.239.223.2558,190
12813.239.224.0/1913.239.224.1 to 13.239.255.25413.239.255.2558,190
12913.240.0.0/1913.240.0.1 to 13.240.31.25413.240.31.2558,190
13013.240.32.0/1913.240.32.1 to 13.240.63.25413.240.63.2558,190
13113.240.64.0/1913.240.64.1 to 13.240.95.25413.240.95.2558,190
13213.240.96.0/1913.240.96.1 to 13.240.127.25413.240.127.2558,190
13313.240.128.0/1913.240.128.1 to 13.240.159.25413.240.159.2558,190
13413.240.160.0/1913.240.160.1 to 13.240.191.25413.240.191.2558,190
13513.240.192.0/1913.240.192.1 to 13.240.223.25413.240.223.2558,190
13613.240.224.0/1913.240.224.1 to 13.240.255.25413.240.255.2558,190
13713.241.0.0/1913.241.0.1 to 13.241.31.25413.241.31.2558,190
13813.241.32.0/1913.241.32.1 to 13.241.63.25413.241.63.2558,190
13913.241.64.0/1913.241.64.1 to 13.241.95.25413.241.95.2558,190
14013.241.96.0/1913.241.96.1 to 13.241.127.25413.241.127.2558,190
14113.241.128.0/1913.241.128.1 to 13.241.159.25413.241.159.2558,190
14213.241.160.0/1913.241.160.1 to 13.241.191.25413.241.191.2558,190
14313.241.192.0/1913.241.192.1 to 13.241.223.25413.241.223.2558,190
14413.241.224.0/1913.241.224.1 to 13.241.255.25413.241.255.2558,190
14513.242.0.0/1913.242.0.1 to 13.242.31.25413.242.31.2558,190
14613.242.32.0/1913.242.32.1 to 13.242.63.25413.242.63.2558,190
14713.242.64.0/1913.242.64.1 to 13.242.95.25413.242.95.2558,190
14813.242.96.0/1913.242.96.1 to 13.242.127.25413.242.127.2558,190
14913.242.128.0/1913.242.128.1 to 13.242.159.25413.242.159.2558,190
15013.242.160.0/1913.242.160.1 to 13.242.191.25413.242.191.2558,190
15113.242.192.0/1913.242.192.1 to 13.242.223.25413.242.223.2558,190
15213.242.224.0/1913.242.224.1 to 13.242.255.25413.242.255.2558,190
15313.243.0.0/1913.243.0.1 to 13.243.31.25413.243.31.2558,190
15413.243.32.0/1913.243.32.1 to 13.243.63.25413.243.63.2558,190
15513.243.64.0/1913.243.64.1 to 13.243.95.25413.243.95.2558,190
15613.243.96.0/1913.243.96.1 to 13.243.127.25413.243.127.2558,190
15713.243.128.0/1913.243.128.1 to 13.243.159.25413.243.159.2558,190
15813.243.160.0/1913.243.160.1 to 13.243.191.25413.243.191.2558,190
15913.243.192.0/1913.243.192.1 to 13.243.223.25413.243.223.2558,190
16013.243.224.0/1913.243.224.1 to 13.243.255.25413.243.255.2558,190
16113.244.0.0/1913.244.0.1 to 13.244.31.25413.244.31.2558,190
16213.244.32.0/1913.244.32.1 to 13.244.63.25413.244.63.2558,190
16313.244.64.0/1913.244.64.1 to 13.244.95.25413.244.95.2558,190
16413.244.96.0/1913.244.96.1 to 13.244.127.25413.244.127.2558,190
16513.244.128.0/1913.244.128.1 to 13.244.159.25413.244.159.2558,190
16613.244.160.0/1913.244.160.1 to 13.244.191.25413.244.191.2558,190
16713.244.192.0/1913.244.192.1 to 13.244.223.25413.244.223.2558,190
16813.244.224.0/1913.244.224.1 to 13.244.255.25413.244.255.2558,190
16913.245.0.0/1913.245.0.1 to 13.245.31.25413.245.31.2558,190
17013.245.32.0/1913.245.32.1 to 13.245.63.25413.245.63.2558,190
17113.245.64.0/1913.245.64.1 to 13.245.95.25413.245.95.2558,190
17213.245.96.0/1913.245.96.1 to 13.245.127.25413.245.127.2558,190
17313.245.128.0/1913.245.128.1 to 13.245.159.25413.245.159.2558,190
17413.245.160.0/1913.245.160.1 to 13.245.191.25413.245.191.2558,190
17513.245.192.0/1913.245.192.1 to 13.245.223.25413.245.223.2558,190
17613.245.224.0/1913.245.224.1 to 13.245.255.25413.245.255.2558,190
17713.246.0.0/1913.246.0.1 to 13.246.31.25413.246.31.2558,190
17813.246.32.0/1913.246.32.1 to 13.246.63.25413.246.63.2558,190
17913.246.64.0/1913.246.64.1 to 13.246.95.25413.246.95.2558,190
18013.246.96.0/1913.246.96.1 to 13.246.127.25413.246.127.2558,190
18113.246.128.0/1913.246.128.1 to 13.246.159.25413.246.159.2558,190
18213.246.160.0/1913.246.160.1 to 13.246.191.25413.246.191.2558,190
18313.246.192.0/1913.246.192.1 to 13.246.223.25413.246.223.2558,190
18413.246.224.0/1913.246.224.1 to 13.246.255.25413.246.255.2558,190
18513.247.0.0/1913.247.0.1 to 13.247.31.25413.247.31.2558,190
18613.247.32.0/1913.247.32.1 to 13.247.63.25413.247.63.2558,190
18713.247.64.0/1913.247.64.1 to 13.247.95.25413.247.95.2558,190
18813.247.96.0/1913.247.96.1 to 13.247.127.25413.247.127.2558,190
18913.247.128.0/1913.247.128.1 to 13.247.159.25413.247.159.2558,190
19013.247.160.0/1913.247.160.1 to 13.247.191.25413.247.191.2558,190
19113.247.192.0/1913.247.192.1 to 13.247.223.25413.247.223.2558,190
19213.247.224.0/1913.247.224.1 to 13.247.255.25413.247.255.2558,190
19313.248.0.0/1913.248.0.1 to 13.248.31.25413.248.31.2558,190
19413.248.32.0/1913.248.32.1 to 13.248.63.25413.248.63.2558,190
19513.248.64.0/1913.248.64.1 to 13.248.95.25413.248.95.2558,190
19613.248.96.0/1913.248.96.1 to 13.248.127.25413.248.127.2558,190
19713.248.128.0/1913.248.128.1 to 13.248.159.25413.248.159.2558,190
19813.248.160.0/1913.248.160.1 to 13.248.191.25413.248.191.2558,190
19913.248.192.0/1913.248.192.1 to 13.248.223.25413.248.223.2558,190
20013.248.224.0/1913.248.224.1 to 13.248.255.25413.248.255.2558,190
20113.249.0.0/1913.249.0.1 to 13.249.31.25413.249.31.2558,190
20213.249.32.0/1913.249.32.1 to 13.249.63.25413.249.63.2558,190
20313.249.64.0/1913.249.64.1 to 13.249.95.25413.249.95.2558,190
20413.249.96.0/1913.249.96.1 to 13.249.127.25413.249.127.2558,190
20513.249.128.0/1913.249.128.1 to 13.249.159.25413.249.159.2558,190
20613.249.160.0/1913.249.160.1 to 13.249.191.25413.249.191.2558,190
20713.249.192.0/1913.249.192.1 to 13.249.223.25413.249.223.2558,190
20813.249.224.0/1913.249.224.1 to 13.249.255.25413.249.255.2558,190
20913.250.0.0/1913.250.0.1 to 13.250.31.25413.250.31.2558,190
21013.250.32.0/1913.250.32.1 to 13.250.63.25413.250.63.2558,190
21113.250.64.0/1913.250.64.1 to 13.250.95.25413.250.95.2558,190
21213.250.96.0/1913.250.96.1 to 13.250.127.25413.250.127.2558,190
21313.250.128.0/1913.250.128.1 to 13.250.159.25413.250.159.2558,190
21413.250.160.0/1913.250.160.1 to 13.250.191.25413.250.191.2558,190
21513.250.192.0/1913.250.192.1 to 13.250.223.25413.250.223.2558,190
21613.250.224.0/1913.250.224.1 to 13.250.255.25413.250.255.2558,190
21713.251.0.0/1913.251.0.1 to 13.251.31.25413.251.31.2558,190
21813.251.32.0/1913.251.32.1 to 13.251.63.25413.251.63.2558,190
21913.251.64.0/1913.251.64.1 to 13.251.95.25413.251.95.2558,190
22013.251.96.0/1913.251.96.1 to 13.251.127.25413.251.127.2558,190
22113.251.128.0/1913.251.128.1 to 13.251.159.25413.251.159.2558,190
22213.251.160.0/1913.251.160.1 to 13.251.191.25413.251.191.2558,190
22313.251.192.0/1913.251.192.1 to 13.251.223.25413.251.223.2558,190
22413.251.224.0/1913.251.224.1 to 13.251.255.25413.251.255.2558,190
22513.252.0.0/1913.252.0.1 to 13.252.31.25413.252.31.2558,190
22613.252.32.0/1913.252.32.1 to 13.252.63.25413.252.63.2558,190
22713.252.64.0/1913.252.64.1 to 13.252.95.25413.252.95.2558,190
22813.252.96.0/1913.252.96.1 to 13.252.127.25413.252.127.2558,190
22913.252.128.0/1913.252.128.1 to 13.252.159.25413.252.159.2558,190
23013.252.160.0/1913.252.160.1 to 13.252.191.25413.252.191.2558,190
23113.252.192.0/1913.252.192.1 to 13.252.223.25413.252.223.2558,190
23213.252.224.0/1913.252.224.1 to 13.252.255.25413.252.255.2558,190
23313.253.0.0/1913.253.0.1 to 13.253.31.25413.253.31.2558,190
23413.253.32.0/1913.253.32.1 to 13.253.63.25413.253.63.2558,190
23513.253.64.0/1913.253.64.1 to 13.253.95.25413.253.95.2558,190
23613.253.96.0/1913.253.96.1 to 13.253.127.25413.253.127.2558,190
23713.253.128.0/1913.253.128.1 to 13.253.159.25413.253.159.2558,190
23813.253.160.0/1913.253.160.1 to 13.253.191.25413.253.191.2558,190
23913.253.192.0/1913.253.192.1 to 13.253.223.25413.253.223.2558,190
24013.253.224.0/1913.253.224.1 to 13.253.255.25413.253.255.2558,190
24113.254.0.0/1913.254.0.1 to 13.254.31.25413.254.31.2558,190
24213.254.32.0/1913.254.32.1 to 13.254.63.25413.254.63.2558,190
24313.254.64.0/1913.254.64.1 to 13.254.95.25413.254.95.2558,190
24413.254.96.0/1913.254.96.1 to 13.254.127.25413.254.127.2558,190
24513.254.128.0/1913.254.128.1 to 13.254.159.25413.254.159.2558,190
24613.254.160.0/1913.254.160.1 to 13.254.191.25413.254.191.2558,190
24713.254.192.0/1913.254.192.1 to 13.254.223.25413.254.223.2558,190
24813.254.224.0/1913.254.224.1 to 13.254.255.25413.254.255.2558,190
24913.255.0.0/1913.255.0.1 to 13.255.31.25413.255.31.2558,190
25013.255.32.0/1913.255.32.1 to 13.255.63.25413.255.63.2558,190
25113.255.64.0/1913.255.64.1 to 13.255.95.25413.255.95.2558,190
25213.255.96.0/1913.255.96.1 to 13.255.127.25413.255.127.2558,190
25313.255.128.0/1913.255.128.1 to 13.255.159.25413.255.159.2558,190
25413.255.160.0/1913.255.160.1 to 13.255.191.25413.255.191.2558,190
25513.255.192.0/1913.255.192.1 to 13.255.223.25413.255.223.2558,190
25613.255.224.0/1913.255.224.1 to 13.255.255.25413.255.255.2558,190

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.