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.

Network58.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
58.0.0.0
Broadcast address
58.255.255.255
First usable
58.0.0.1
Last usable
58.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 3A000000 · Integer 973078528 to 989855743
Reverse DNS zone
58.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00111010..00000000.00000000.0000000058.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00111010..00000000.00000000.0000000058.0.0.0
Broadcast00111010..11111111.11111111.1111111158.255.255.255
Split into smaller subnets/20
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

58.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
158.0.0.0/2058.0.0.1 to 58.0.15.25458.0.15.2554,094
258.0.16.0/2058.0.16.1 to 58.0.31.25458.0.31.2554,094
358.0.32.0/2058.0.32.1 to 58.0.47.25458.0.47.2554,094
458.0.48.0/2058.0.48.1 to 58.0.63.25458.0.63.2554,094
558.0.64.0/2058.0.64.1 to 58.0.79.25458.0.79.2554,094
658.0.80.0/2058.0.80.1 to 58.0.95.25458.0.95.2554,094
758.0.96.0/2058.0.96.1 to 58.0.111.25458.0.111.2554,094
858.0.112.0/2058.0.112.1 to 58.0.127.25458.0.127.2554,094
958.0.128.0/2058.0.128.1 to 58.0.143.25458.0.143.2554,094
1058.0.144.0/2058.0.144.1 to 58.0.159.25458.0.159.2554,094
1158.0.160.0/2058.0.160.1 to 58.0.175.25458.0.175.2554,094
1258.0.176.0/2058.0.176.1 to 58.0.191.25458.0.191.2554,094
1358.0.192.0/2058.0.192.1 to 58.0.207.25458.0.207.2554,094
1458.0.208.0/2058.0.208.1 to 58.0.223.25458.0.223.2554,094
1558.0.224.0/2058.0.224.1 to 58.0.239.25458.0.239.2554,094
1658.0.240.0/2058.0.240.1 to 58.0.255.25458.0.255.2554,094
1758.1.0.0/2058.1.0.1 to 58.1.15.25458.1.15.2554,094
1858.1.16.0/2058.1.16.1 to 58.1.31.25458.1.31.2554,094
1958.1.32.0/2058.1.32.1 to 58.1.47.25458.1.47.2554,094
2058.1.48.0/2058.1.48.1 to 58.1.63.25458.1.63.2554,094
2158.1.64.0/2058.1.64.1 to 58.1.79.25458.1.79.2554,094
2258.1.80.0/2058.1.80.1 to 58.1.95.25458.1.95.2554,094
2358.1.96.0/2058.1.96.1 to 58.1.111.25458.1.111.2554,094
2458.1.112.0/2058.1.112.1 to 58.1.127.25458.1.127.2554,094
2558.1.128.0/2058.1.128.1 to 58.1.143.25458.1.143.2554,094
2658.1.144.0/2058.1.144.1 to 58.1.159.25458.1.159.2554,094
2758.1.160.0/2058.1.160.1 to 58.1.175.25458.1.175.2554,094
2858.1.176.0/2058.1.176.1 to 58.1.191.25458.1.191.2554,094
2958.1.192.0/2058.1.192.1 to 58.1.207.25458.1.207.2554,094
3058.1.208.0/2058.1.208.1 to 58.1.223.25458.1.223.2554,094
3158.1.224.0/2058.1.224.1 to 58.1.239.25458.1.239.2554,094
3258.1.240.0/2058.1.240.1 to 58.1.255.25458.1.255.2554,094
3358.2.0.0/2058.2.0.1 to 58.2.15.25458.2.15.2554,094
3458.2.16.0/2058.2.16.1 to 58.2.31.25458.2.31.2554,094
3558.2.32.0/2058.2.32.1 to 58.2.47.25458.2.47.2554,094
3658.2.48.0/2058.2.48.1 to 58.2.63.25458.2.63.2554,094
3758.2.64.0/2058.2.64.1 to 58.2.79.25458.2.79.2554,094
3858.2.80.0/2058.2.80.1 to 58.2.95.25458.2.95.2554,094
3958.2.96.0/2058.2.96.1 to 58.2.111.25458.2.111.2554,094
4058.2.112.0/2058.2.112.1 to 58.2.127.25458.2.127.2554,094
4158.2.128.0/2058.2.128.1 to 58.2.143.25458.2.143.2554,094
4258.2.144.0/2058.2.144.1 to 58.2.159.25458.2.159.2554,094
4358.2.160.0/2058.2.160.1 to 58.2.175.25458.2.175.2554,094
4458.2.176.0/2058.2.176.1 to 58.2.191.25458.2.191.2554,094
4558.2.192.0/2058.2.192.1 to 58.2.207.25458.2.207.2554,094
4658.2.208.0/2058.2.208.1 to 58.2.223.25458.2.223.2554,094
4758.2.224.0/2058.2.224.1 to 58.2.239.25458.2.239.2554,094
4858.2.240.0/2058.2.240.1 to 58.2.255.25458.2.255.2554,094
4958.3.0.0/2058.3.0.1 to 58.3.15.25458.3.15.2554,094
5058.3.16.0/2058.3.16.1 to 58.3.31.25458.3.31.2554,094
5158.3.32.0/2058.3.32.1 to 58.3.47.25458.3.47.2554,094
5258.3.48.0/2058.3.48.1 to 58.3.63.25458.3.63.2554,094
5358.3.64.0/2058.3.64.1 to 58.3.79.25458.3.79.2554,094
5458.3.80.0/2058.3.80.1 to 58.3.95.25458.3.95.2554,094
5558.3.96.0/2058.3.96.1 to 58.3.111.25458.3.111.2554,094
5658.3.112.0/2058.3.112.1 to 58.3.127.25458.3.127.2554,094
5758.3.128.0/2058.3.128.1 to 58.3.143.25458.3.143.2554,094
5858.3.144.0/2058.3.144.1 to 58.3.159.25458.3.159.2554,094
5958.3.160.0/2058.3.160.1 to 58.3.175.25458.3.175.2554,094
6058.3.176.0/2058.3.176.1 to 58.3.191.25458.3.191.2554,094
6158.3.192.0/2058.3.192.1 to 58.3.207.25458.3.207.2554,094
6258.3.208.0/2058.3.208.1 to 58.3.223.25458.3.223.2554,094
6358.3.224.0/2058.3.224.1 to 58.3.239.25458.3.239.2554,094
6458.3.240.0/2058.3.240.1 to 58.3.255.25458.3.255.2554,094
6558.4.0.0/2058.4.0.1 to 58.4.15.25458.4.15.2554,094
6658.4.16.0/2058.4.16.1 to 58.4.31.25458.4.31.2554,094
6758.4.32.0/2058.4.32.1 to 58.4.47.25458.4.47.2554,094
6858.4.48.0/2058.4.48.1 to 58.4.63.25458.4.63.2554,094
6958.4.64.0/2058.4.64.1 to 58.4.79.25458.4.79.2554,094
7058.4.80.0/2058.4.80.1 to 58.4.95.25458.4.95.2554,094
7158.4.96.0/2058.4.96.1 to 58.4.111.25458.4.111.2554,094
7258.4.112.0/2058.4.112.1 to 58.4.127.25458.4.127.2554,094
7358.4.128.0/2058.4.128.1 to 58.4.143.25458.4.143.2554,094
7458.4.144.0/2058.4.144.1 to 58.4.159.25458.4.159.2554,094
7558.4.160.0/2058.4.160.1 to 58.4.175.25458.4.175.2554,094
7658.4.176.0/2058.4.176.1 to 58.4.191.25458.4.191.2554,094
7758.4.192.0/2058.4.192.1 to 58.4.207.25458.4.207.2554,094
7858.4.208.0/2058.4.208.1 to 58.4.223.25458.4.223.2554,094
7958.4.224.0/2058.4.224.1 to 58.4.239.25458.4.239.2554,094
8058.4.240.0/2058.4.240.1 to 58.4.255.25458.4.255.2554,094
8158.5.0.0/2058.5.0.1 to 58.5.15.25458.5.15.2554,094
8258.5.16.0/2058.5.16.1 to 58.5.31.25458.5.31.2554,094
8358.5.32.0/2058.5.32.1 to 58.5.47.25458.5.47.2554,094
8458.5.48.0/2058.5.48.1 to 58.5.63.25458.5.63.2554,094
8558.5.64.0/2058.5.64.1 to 58.5.79.25458.5.79.2554,094
8658.5.80.0/2058.5.80.1 to 58.5.95.25458.5.95.2554,094
8758.5.96.0/2058.5.96.1 to 58.5.111.25458.5.111.2554,094
8858.5.112.0/2058.5.112.1 to 58.5.127.25458.5.127.2554,094
8958.5.128.0/2058.5.128.1 to 58.5.143.25458.5.143.2554,094
9058.5.144.0/2058.5.144.1 to 58.5.159.25458.5.159.2554,094
9158.5.160.0/2058.5.160.1 to 58.5.175.25458.5.175.2554,094
9258.5.176.0/2058.5.176.1 to 58.5.191.25458.5.191.2554,094
9358.5.192.0/2058.5.192.1 to 58.5.207.25458.5.207.2554,094
9458.5.208.0/2058.5.208.1 to 58.5.223.25458.5.223.2554,094
9558.5.224.0/2058.5.224.1 to 58.5.239.25458.5.239.2554,094
9658.5.240.0/2058.5.240.1 to 58.5.255.25458.5.255.2554,094
9758.6.0.0/2058.6.0.1 to 58.6.15.25458.6.15.2554,094
9858.6.16.0/2058.6.16.1 to 58.6.31.25458.6.31.2554,094
9958.6.32.0/2058.6.32.1 to 58.6.47.25458.6.47.2554,094
10058.6.48.0/2058.6.48.1 to 58.6.63.25458.6.63.2554,094
10158.6.64.0/2058.6.64.1 to 58.6.79.25458.6.79.2554,094
10258.6.80.0/2058.6.80.1 to 58.6.95.25458.6.95.2554,094
10358.6.96.0/2058.6.96.1 to 58.6.111.25458.6.111.2554,094
10458.6.112.0/2058.6.112.1 to 58.6.127.25458.6.127.2554,094
10558.6.128.0/2058.6.128.1 to 58.6.143.25458.6.143.2554,094
10658.6.144.0/2058.6.144.1 to 58.6.159.25458.6.159.2554,094
10758.6.160.0/2058.6.160.1 to 58.6.175.25458.6.175.2554,094
10858.6.176.0/2058.6.176.1 to 58.6.191.25458.6.191.2554,094
10958.6.192.0/2058.6.192.1 to 58.6.207.25458.6.207.2554,094
11058.6.208.0/2058.6.208.1 to 58.6.223.25458.6.223.2554,094
11158.6.224.0/2058.6.224.1 to 58.6.239.25458.6.239.2554,094
11258.6.240.0/2058.6.240.1 to 58.6.255.25458.6.255.2554,094
11358.7.0.0/2058.7.0.1 to 58.7.15.25458.7.15.2554,094
11458.7.16.0/2058.7.16.1 to 58.7.31.25458.7.31.2554,094
11558.7.32.0/2058.7.32.1 to 58.7.47.25458.7.47.2554,094
11658.7.48.0/2058.7.48.1 to 58.7.63.25458.7.63.2554,094
11758.7.64.0/2058.7.64.1 to 58.7.79.25458.7.79.2554,094
11858.7.80.0/2058.7.80.1 to 58.7.95.25458.7.95.2554,094
11958.7.96.0/2058.7.96.1 to 58.7.111.25458.7.111.2554,094
12058.7.112.0/2058.7.112.1 to 58.7.127.25458.7.127.2554,094
12158.7.128.0/2058.7.128.1 to 58.7.143.25458.7.143.2554,094
12258.7.144.0/2058.7.144.1 to 58.7.159.25458.7.159.2554,094
12358.7.160.0/2058.7.160.1 to 58.7.175.25458.7.175.2554,094
12458.7.176.0/2058.7.176.1 to 58.7.191.25458.7.191.2554,094
12558.7.192.0/2058.7.192.1 to 58.7.207.25458.7.207.2554,094
12658.7.208.0/2058.7.208.1 to 58.7.223.25458.7.223.2554,094
12758.7.224.0/2058.7.224.1 to 58.7.239.25458.7.239.2554,094
12858.7.240.0/2058.7.240.1 to 58.7.255.25458.7.255.2554,094
12958.8.0.0/2058.8.0.1 to 58.8.15.25458.8.15.2554,094
13058.8.16.0/2058.8.16.1 to 58.8.31.25458.8.31.2554,094
13158.8.32.0/2058.8.32.1 to 58.8.47.25458.8.47.2554,094
13258.8.48.0/2058.8.48.1 to 58.8.63.25458.8.63.2554,094
13358.8.64.0/2058.8.64.1 to 58.8.79.25458.8.79.2554,094
13458.8.80.0/2058.8.80.1 to 58.8.95.25458.8.95.2554,094
13558.8.96.0/2058.8.96.1 to 58.8.111.25458.8.111.2554,094
13658.8.112.0/2058.8.112.1 to 58.8.127.25458.8.127.2554,094
13758.8.128.0/2058.8.128.1 to 58.8.143.25458.8.143.2554,094
13858.8.144.0/2058.8.144.1 to 58.8.159.25458.8.159.2554,094
13958.8.160.0/2058.8.160.1 to 58.8.175.25458.8.175.2554,094
14058.8.176.0/2058.8.176.1 to 58.8.191.25458.8.191.2554,094
14158.8.192.0/2058.8.192.1 to 58.8.207.25458.8.207.2554,094
14258.8.208.0/2058.8.208.1 to 58.8.223.25458.8.223.2554,094
14358.8.224.0/2058.8.224.1 to 58.8.239.25458.8.239.2554,094
14458.8.240.0/2058.8.240.1 to 58.8.255.25458.8.255.2554,094
14558.9.0.0/2058.9.0.1 to 58.9.15.25458.9.15.2554,094
14658.9.16.0/2058.9.16.1 to 58.9.31.25458.9.31.2554,094
14758.9.32.0/2058.9.32.1 to 58.9.47.25458.9.47.2554,094
14858.9.48.0/2058.9.48.1 to 58.9.63.25458.9.63.2554,094
14958.9.64.0/2058.9.64.1 to 58.9.79.25458.9.79.2554,094
15058.9.80.0/2058.9.80.1 to 58.9.95.25458.9.95.2554,094
15158.9.96.0/2058.9.96.1 to 58.9.111.25458.9.111.2554,094
15258.9.112.0/2058.9.112.1 to 58.9.127.25458.9.127.2554,094
15358.9.128.0/2058.9.128.1 to 58.9.143.25458.9.143.2554,094
15458.9.144.0/2058.9.144.1 to 58.9.159.25458.9.159.2554,094
15558.9.160.0/2058.9.160.1 to 58.9.175.25458.9.175.2554,094
15658.9.176.0/2058.9.176.1 to 58.9.191.25458.9.191.2554,094
15758.9.192.0/2058.9.192.1 to 58.9.207.25458.9.207.2554,094
15858.9.208.0/2058.9.208.1 to 58.9.223.25458.9.223.2554,094
15958.9.224.0/2058.9.224.1 to 58.9.239.25458.9.239.2554,094
16058.9.240.0/2058.9.240.1 to 58.9.255.25458.9.255.2554,094
16158.10.0.0/2058.10.0.1 to 58.10.15.25458.10.15.2554,094
16258.10.16.0/2058.10.16.1 to 58.10.31.25458.10.31.2554,094
16358.10.32.0/2058.10.32.1 to 58.10.47.25458.10.47.2554,094
16458.10.48.0/2058.10.48.1 to 58.10.63.25458.10.63.2554,094
16558.10.64.0/2058.10.64.1 to 58.10.79.25458.10.79.2554,094
16658.10.80.0/2058.10.80.1 to 58.10.95.25458.10.95.2554,094
16758.10.96.0/2058.10.96.1 to 58.10.111.25458.10.111.2554,094
16858.10.112.0/2058.10.112.1 to 58.10.127.25458.10.127.2554,094
16958.10.128.0/2058.10.128.1 to 58.10.143.25458.10.143.2554,094
17058.10.144.0/2058.10.144.1 to 58.10.159.25458.10.159.2554,094
17158.10.160.0/2058.10.160.1 to 58.10.175.25458.10.175.2554,094
17258.10.176.0/2058.10.176.1 to 58.10.191.25458.10.191.2554,094
17358.10.192.0/2058.10.192.1 to 58.10.207.25458.10.207.2554,094
17458.10.208.0/2058.10.208.1 to 58.10.223.25458.10.223.2554,094
17558.10.224.0/2058.10.224.1 to 58.10.239.25458.10.239.2554,094
17658.10.240.0/2058.10.240.1 to 58.10.255.25458.10.255.2554,094
17758.11.0.0/2058.11.0.1 to 58.11.15.25458.11.15.2554,094
17858.11.16.0/2058.11.16.1 to 58.11.31.25458.11.31.2554,094
17958.11.32.0/2058.11.32.1 to 58.11.47.25458.11.47.2554,094
18058.11.48.0/2058.11.48.1 to 58.11.63.25458.11.63.2554,094
18158.11.64.0/2058.11.64.1 to 58.11.79.25458.11.79.2554,094
18258.11.80.0/2058.11.80.1 to 58.11.95.25458.11.95.2554,094
18358.11.96.0/2058.11.96.1 to 58.11.111.25458.11.111.2554,094
18458.11.112.0/2058.11.112.1 to 58.11.127.25458.11.127.2554,094
18558.11.128.0/2058.11.128.1 to 58.11.143.25458.11.143.2554,094
18658.11.144.0/2058.11.144.1 to 58.11.159.25458.11.159.2554,094
18758.11.160.0/2058.11.160.1 to 58.11.175.25458.11.175.2554,094
18858.11.176.0/2058.11.176.1 to 58.11.191.25458.11.191.2554,094
18958.11.192.0/2058.11.192.1 to 58.11.207.25458.11.207.2554,094
19058.11.208.0/2058.11.208.1 to 58.11.223.25458.11.223.2554,094
19158.11.224.0/2058.11.224.1 to 58.11.239.25458.11.239.2554,094
19258.11.240.0/2058.11.240.1 to 58.11.255.25458.11.255.2554,094
19358.12.0.0/2058.12.0.1 to 58.12.15.25458.12.15.2554,094
19458.12.16.0/2058.12.16.1 to 58.12.31.25458.12.31.2554,094
19558.12.32.0/2058.12.32.1 to 58.12.47.25458.12.47.2554,094
19658.12.48.0/2058.12.48.1 to 58.12.63.25458.12.63.2554,094
19758.12.64.0/2058.12.64.1 to 58.12.79.25458.12.79.2554,094
19858.12.80.0/2058.12.80.1 to 58.12.95.25458.12.95.2554,094
19958.12.96.0/2058.12.96.1 to 58.12.111.25458.12.111.2554,094
20058.12.112.0/2058.12.112.1 to 58.12.127.25458.12.127.2554,094
20158.12.128.0/2058.12.128.1 to 58.12.143.25458.12.143.2554,094
20258.12.144.0/2058.12.144.1 to 58.12.159.25458.12.159.2554,094
20358.12.160.0/2058.12.160.1 to 58.12.175.25458.12.175.2554,094
20458.12.176.0/2058.12.176.1 to 58.12.191.25458.12.191.2554,094
20558.12.192.0/2058.12.192.1 to 58.12.207.25458.12.207.2554,094
20658.12.208.0/2058.12.208.1 to 58.12.223.25458.12.223.2554,094
20758.12.224.0/2058.12.224.1 to 58.12.239.25458.12.239.2554,094
20858.12.240.0/2058.12.240.1 to 58.12.255.25458.12.255.2554,094
20958.13.0.0/2058.13.0.1 to 58.13.15.25458.13.15.2554,094
21058.13.16.0/2058.13.16.1 to 58.13.31.25458.13.31.2554,094
21158.13.32.0/2058.13.32.1 to 58.13.47.25458.13.47.2554,094
21258.13.48.0/2058.13.48.1 to 58.13.63.25458.13.63.2554,094
21358.13.64.0/2058.13.64.1 to 58.13.79.25458.13.79.2554,094
21458.13.80.0/2058.13.80.1 to 58.13.95.25458.13.95.2554,094
21558.13.96.0/2058.13.96.1 to 58.13.111.25458.13.111.2554,094
21658.13.112.0/2058.13.112.1 to 58.13.127.25458.13.127.2554,094
21758.13.128.0/2058.13.128.1 to 58.13.143.25458.13.143.2554,094
21858.13.144.0/2058.13.144.1 to 58.13.159.25458.13.159.2554,094
21958.13.160.0/2058.13.160.1 to 58.13.175.25458.13.175.2554,094
22058.13.176.0/2058.13.176.1 to 58.13.191.25458.13.191.2554,094
22158.13.192.0/2058.13.192.1 to 58.13.207.25458.13.207.2554,094
22258.13.208.0/2058.13.208.1 to 58.13.223.25458.13.223.2554,094
22358.13.224.0/2058.13.224.1 to 58.13.239.25458.13.239.2554,094
22458.13.240.0/2058.13.240.1 to 58.13.255.25458.13.255.2554,094
22558.14.0.0/2058.14.0.1 to 58.14.15.25458.14.15.2554,094
22658.14.16.0/2058.14.16.1 to 58.14.31.25458.14.31.2554,094
22758.14.32.0/2058.14.32.1 to 58.14.47.25458.14.47.2554,094
22858.14.48.0/2058.14.48.1 to 58.14.63.25458.14.63.2554,094
22958.14.64.0/2058.14.64.1 to 58.14.79.25458.14.79.2554,094
23058.14.80.0/2058.14.80.1 to 58.14.95.25458.14.95.2554,094
23158.14.96.0/2058.14.96.1 to 58.14.111.25458.14.111.2554,094
23258.14.112.0/2058.14.112.1 to 58.14.127.25458.14.127.2554,094
23358.14.128.0/2058.14.128.1 to 58.14.143.25458.14.143.2554,094
23458.14.144.0/2058.14.144.1 to 58.14.159.25458.14.159.2554,094
23558.14.160.0/2058.14.160.1 to 58.14.175.25458.14.175.2554,094
23658.14.176.0/2058.14.176.1 to 58.14.191.25458.14.191.2554,094
23758.14.192.0/2058.14.192.1 to 58.14.207.25458.14.207.2554,094
23858.14.208.0/2058.14.208.1 to 58.14.223.25458.14.223.2554,094
23958.14.224.0/2058.14.224.1 to 58.14.239.25458.14.239.2554,094
24058.14.240.0/2058.14.240.1 to 58.14.255.25458.14.255.2554,094
24158.15.0.0/2058.15.0.1 to 58.15.15.25458.15.15.2554,094
24258.15.16.0/2058.15.16.1 to 58.15.31.25458.15.31.2554,094
24358.15.32.0/2058.15.32.1 to 58.15.47.25458.15.47.2554,094
24458.15.48.0/2058.15.48.1 to 58.15.63.25458.15.63.2554,094
24558.15.64.0/2058.15.64.1 to 58.15.79.25458.15.79.2554,094
24658.15.80.0/2058.15.80.1 to 58.15.95.25458.15.95.2554,094
24758.15.96.0/2058.15.96.1 to 58.15.111.25458.15.111.2554,094
24858.15.112.0/2058.15.112.1 to 58.15.127.25458.15.127.2554,094
24958.15.128.0/2058.15.128.1 to 58.15.143.25458.15.143.2554,094
25058.15.144.0/2058.15.144.1 to 58.15.159.25458.15.159.2554,094
25158.15.160.0/2058.15.160.1 to 58.15.175.25458.15.175.2554,094
25258.15.176.0/2058.15.176.1 to 58.15.191.25458.15.191.2554,094
25358.15.192.0/2058.15.192.1 to 58.15.207.25458.15.207.2554,094
25458.15.208.0/2058.15.208.1 to 58.15.223.25458.15.223.2554,094
25558.15.224.0/2058.15.224.1 to 58.15.239.25458.15.239.2554,094
25658.15.240.0/2058.15.240.1 to 58.15.255.25458.15.255.2554,094

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.