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.

Network60.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
60.0.0.0
Broadcast address
60.127.255.255
First usable
60.0.0.1
Last usable
60.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 3C000000 · Integer 1006632960 to 1015021567
Reverse DNS zones
0.60.in-addr.arpa
1.60.in-addr.arpa
2.60.in-addr.arpa
3.60.in-addr.arpa
4.60.in-addr.arpa
5.60.in-addr.arpa
6.60.in-addr.arpa
7.60.in-addr.arpa
8.60.in-addr.arpa
9.60.in-addr.arpa
10.60.in-addr.arpa
11.60.in-addr.arpa
12.60.in-addr.arpa
13.60.in-addr.arpa
14.60.in-addr.arpa
15.60.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00111100.00000000.00000000.0000000060.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00111100.00000000.00000000.0000000060.0.0.0
Broadcast00111100.01111111.11111111.1111111160.127.255.255
Split into smaller subnets/21
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

60.0.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
160.0.0.0/2160.0.0.1 to 60.0.7.25460.0.7.2552,046
260.0.8.0/2160.0.8.1 to 60.0.15.25460.0.15.2552,046
360.0.16.0/2160.0.16.1 to 60.0.23.25460.0.23.2552,046
460.0.24.0/2160.0.24.1 to 60.0.31.25460.0.31.2552,046
560.0.32.0/2160.0.32.1 to 60.0.39.25460.0.39.2552,046
660.0.40.0/2160.0.40.1 to 60.0.47.25460.0.47.2552,046
760.0.48.0/2160.0.48.1 to 60.0.55.25460.0.55.2552,046
860.0.56.0/2160.0.56.1 to 60.0.63.25460.0.63.2552,046
960.0.64.0/2160.0.64.1 to 60.0.71.25460.0.71.2552,046
1060.0.72.0/2160.0.72.1 to 60.0.79.25460.0.79.2552,046
1160.0.80.0/2160.0.80.1 to 60.0.87.25460.0.87.2552,046
1260.0.88.0/2160.0.88.1 to 60.0.95.25460.0.95.2552,046
1360.0.96.0/2160.0.96.1 to 60.0.103.25460.0.103.2552,046
1460.0.104.0/2160.0.104.1 to 60.0.111.25460.0.111.2552,046
1560.0.112.0/2160.0.112.1 to 60.0.119.25460.0.119.2552,046
1660.0.120.0/2160.0.120.1 to 60.0.127.25460.0.127.2552,046
1760.0.128.0/2160.0.128.1 to 60.0.135.25460.0.135.2552,046
1860.0.136.0/2160.0.136.1 to 60.0.143.25460.0.143.2552,046
1960.0.144.0/2160.0.144.1 to 60.0.151.25460.0.151.2552,046
2060.0.152.0/2160.0.152.1 to 60.0.159.25460.0.159.2552,046
2160.0.160.0/2160.0.160.1 to 60.0.167.25460.0.167.2552,046
2260.0.168.0/2160.0.168.1 to 60.0.175.25460.0.175.2552,046
2360.0.176.0/2160.0.176.1 to 60.0.183.25460.0.183.2552,046
2460.0.184.0/2160.0.184.1 to 60.0.191.25460.0.191.2552,046
2560.0.192.0/2160.0.192.1 to 60.0.199.25460.0.199.2552,046
2660.0.200.0/2160.0.200.1 to 60.0.207.25460.0.207.2552,046
2760.0.208.0/2160.0.208.1 to 60.0.215.25460.0.215.2552,046
2860.0.216.0/2160.0.216.1 to 60.0.223.25460.0.223.2552,046
2960.0.224.0/2160.0.224.1 to 60.0.231.25460.0.231.2552,046
3060.0.232.0/2160.0.232.1 to 60.0.239.25460.0.239.2552,046
3160.0.240.0/2160.0.240.1 to 60.0.247.25460.0.247.2552,046
3260.0.248.0/2160.0.248.1 to 60.0.255.25460.0.255.2552,046
3360.1.0.0/2160.1.0.1 to 60.1.7.25460.1.7.2552,046
3460.1.8.0/2160.1.8.1 to 60.1.15.25460.1.15.2552,046
3560.1.16.0/2160.1.16.1 to 60.1.23.25460.1.23.2552,046
3660.1.24.0/2160.1.24.1 to 60.1.31.25460.1.31.2552,046
3760.1.32.0/2160.1.32.1 to 60.1.39.25460.1.39.2552,046
3860.1.40.0/2160.1.40.1 to 60.1.47.25460.1.47.2552,046
3960.1.48.0/2160.1.48.1 to 60.1.55.25460.1.55.2552,046
4060.1.56.0/2160.1.56.1 to 60.1.63.25460.1.63.2552,046
4160.1.64.0/2160.1.64.1 to 60.1.71.25460.1.71.2552,046
4260.1.72.0/2160.1.72.1 to 60.1.79.25460.1.79.2552,046
4360.1.80.0/2160.1.80.1 to 60.1.87.25460.1.87.2552,046
4460.1.88.0/2160.1.88.1 to 60.1.95.25460.1.95.2552,046
4560.1.96.0/2160.1.96.1 to 60.1.103.25460.1.103.2552,046
4660.1.104.0/2160.1.104.1 to 60.1.111.25460.1.111.2552,046
4760.1.112.0/2160.1.112.1 to 60.1.119.25460.1.119.2552,046
4860.1.120.0/2160.1.120.1 to 60.1.127.25460.1.127.2552,046
4960.1.128.0/2160.1.128.1 to 60.1.135.25460.1.135.2552,046
5060.1.136.0/2160.1.136.1 to 60.1.143.25460.1.143.2552,046
5160.1.144.0/2160.1.144.1 to 60.1.151.25460.1.151.2552,046
5260.1.152.0/2160.1.152.1 to 60.1.159.25460.1.159.2552,046
5360.1.160.0/2160.1.160.1 to 60.1.167.25460.1.167.2552,046
5460.1.168.0/2160.1.168.1 to 60.1.175.25460.1.175.2552,046
5560.1.176.0/2160.1.176.1 to 60.1.183.25460.1.183.2552,046
5660.1.184.0/2160.1.184.1 to 60.1.191.25460.1.191.2552,046
5760.1.192.0/2160.1.192.1 to 60.1.199.25460.1.199.2552,046
5860.1.200.0/2160.1.200.1 to 60.1.207.25460.1.207.2552,046
5960.1.208.0/2160.1.208.1 to 60.1.215.25460.1.215.2552,046
6060.1.216.0/2160.1.216.1 to 60.1.223.25460.1.223.2552,046
6160.1.224.0/2160.1.224.1 to 60.1.231.25460.1.231.2552,046
6260.1.232.0/2160.1.232.1 to 60.1.239.25460.1.239.2552,046
6360.1.240.0/2160.1.240.1 to 60.1.247.25460.1.247.2552,046
6460.1.248.0/2160.1.248.1 to 60.1.255.25460.1.255.2552,046
6560.2.0.0/2160.2.0.1 to 60.2.7.25460.2.7.2552,046
6660.2.8.0/2160.2.8.1 to 60.2.15.25460.2.15.2552,046
6760.2.16.0/2160.2.16.1 to 60.2.23.25460.2.23.2552,046
6860.2.24.0/2160.2.24.1 to 60.2.31.25460.2.31.2552,046
6960.2.32.0/2160.2.32.1 to 60.2.39.25460.2.39.2552,046
7060.2.40.0/2160.2.40.1 to 60.2.47.25460.2.47.2552,046
7160.2.48.0/2160.2.48.1 to 60.2.55.25460.2.55.2552,046
7260.2.56.0/2160.2.56.1 to 60.2.63.25460.2.63.2552,046
7360.2.64.0/2160.2.64.1 to 60.2.71.25460.2.71.2552,046
7460.2.72.0/2160.2.72.1 to 60.2.79.25460.2.79.2552,046
7560.2.80.0/2160.2.80.1 to 60.2.87.25460.2.87.2552,046
7660.2.88.0/2160.2.88.1 to 60.2.95.25460.2.95.2552,046
7760.2.96.0/2160.2.96.1 to 60.2.103.25460.2.103.2552,046
7860.2.104.0/2160.2.104.1 to 60.2.111.25460.2.111.2552,046
7960.2.112.0/2160.2.112.1 to 60.2.119.25460.2.119.2552,046
8060.2.120.0/2160.2.120.1 to 60.2.127.25460.2.127.2552,046
8160.2.128.0/2160.2.128.1 to 60.2.135.25460.2.135.2552,046
8260.2.136.0/2160.2.136.1 to 60.2.143.25460.2.143.2552,046
8360.2.144.0/2160.2.144.1 to 60.2.151.25460.2.151.2552,046
8460.2.152.0/2160.2.152.1 to 60.2.159.25460.2.159.2552,046
8560.2.160.0/2160.2.160.1 to 60.2.167.25460.2.167.2552,046
8660.2.168.0/2160.2.168.1 to 60.2.175.25460.2.175.2552,046
8760.2.176.0/2160.2.176.1 to 60.2.183.25460.2.183.2552,046
8860.2.184.0/2160.2.184.1 to 60.2.191.25460.2.191.2552,046
8960.2.192.0/2160.2.192.1 to 60.2.199.25460.2.199.2552,046
9060.2.200.0/2160.2.200.1 to 60.2.207.25460.2.207.2552,046
9160.2.208.0/2160.2.208.1 to 60.2.215.25460.2.215.2552,046
9260.2.216.0/2160.2.216.1 to 60.2.223.25460.2.223.2552,046
9360.2.224.0/2160.2.224.1 to 60.2.231.25460.2.231.2552,046
9460.2.232.0/2160.2.232.1 to 60.2.239.25460.2.239.2552,046
9560.2.240.0/2160.2.240.1 to 60.2.247.25460.2.247.2552,046
9660.2.248.0/2160.2.248.1 to 60.2.255.25460.2.255.2552,046
9760.3.0.0/2160.3.0.1 to 60.3.7.25460.3.7.2552,046
9860.3.8.0/2160.3.8.1 to 60.3.15.25460.3.15.2552,046
9960.3.16.0/2160.3.16.1 to 60.3.23.25460.3.23.2552,046
10060.3.24.0/2160.3.24.1 to 60.3.31.25460.3.31.2552,046
10160.3.32.0/2160.3.32.1 to 60.3.39.25460.3.39.2552,046
10260.3.40.0/2160.3.40.1 to 60.3.47.25460.3.47.2552,046
10360.3.48.0/2160.3.48.1 to 60.3.55.25460.3.55.2552,046
10460.3.56.0/2160.3.56.1 to 60.3.63.25460.3.63.2552,046
10560.3.64.0/2160.3.64.1 to 60.3.71.25460.3.71.2552,046
10660.3.72.0/2160.3.72.1 to 60.3.79.25460.3.79.2552,046
10760.3.80.0/2160.3.80.1 to 60.3.87.25460.3.87.2552,046
10860.3.88.0/2160.3.88.1 to 60.3.95.25460.3.95.2552,046
10960.3.96.0/2160.3.96.1 to 60.3.103.25460.3.103.2552,046
11060.3.104.0/2160.3.104.1 to 60.3.111.25460.3.111.2552,046
11160.3.112.0/2160.3.112.1 to 60.3.119.25460.3.119.2552,046
11260.3.120.0/2160.3.120.1 to 60.3.127.25460.3.127.2552,046
11360.3.128.0/2160.3.128.1 to 60.3.135.25460.3.135.2552,046
11460.3.136.0/2160.3.136.1 to 60.3.143.25460.3.143.2552,046
11560.3.144.0/2160.3.144.1 to 60.3.151.25460.3.151.2552,046
11660.3.152.0/2160.3.152.1 to 60.3.159.25460.3.159.2552,046
11760.3.160.0/2160.3.160.1 to 60.3.167.25460.3.167.2552,046
11860.3.168.0/2160.3.168.1 to 60.3.175.25460.3.175.2552,046
11960.3.176.0/2160.3.176.1 to 60.3.183.25460.3.183.2552,046
12060.3.184.0/2160.3.184.1 to 60.3.191.25460.3.191.2552,046
12160.3.192.0/2160.3.192.1 to 60.3.199.25460.3.199.2552,046
12260.3.200.0/2160.3.200.1 to 60.3.207.25460.3.207.2552,046
12360.3.208.0/2160.3.208.1 to 60.3.215.25460.3.215.2552,046
12460.3.216.0/2160.3.216.1 to 60.3.223.25460.3.223.2552,046
12560.3.224.0/2160.3.224.1 to 60.3.231.25460.3.231.2552,046
12660.3.232.0/2160.3.232.1 to 60.3.239.25460.3.239.2552,046
12760.3.240.0/2160.3.240.1 to 60.3.247.25460.3.247.2552,046
12860.3.248.0/2160.3.248.1 to 60.3.255.25460.3.255.2552,046
12960.4.0.0/2160.4.0.1 to 60.4.7.25460.4.7.2552,046
13060.4.8.0/2160.4.8.1 to 60.4.15.25460.4.15.2552,046
13160.4.16.0/2160.4.16.1 to 60.4.23.25460.4.23.2552,046
13260.4.24.0/2160.4.24.1 to 60.4.31.25460.4.31.2552,046
13360.4.32.0/2160.4.32.1 to 60.4.39.25460.4.39.2552,046
13460.4.40.0/2160.4.40.1 to 60.4.47.25460.4.47.2552,046
13560.4.48.0/2160.4.48.1 to 60.4.55.25460.4.55.2552,046
13660.4.56.0/2160.4.56.1 to 60.4.63.25460.4.63.2552,046
13760.4.64.0/2160.4.64.1 to 60.4.71.25460.4.71.2552,046
13860.4.72.0/2160.4.72.1 to 60.4.79.25460.4.79.2552,046
13960.4.80.0/2160.4.80.1 to 60.4.87.25460.4.87.2552,046
14060.4.88.0/2160.4.88.1 to 60.4.95.25460.4.95.2552,046
14160.4.96.0/2160.4.96.1 to 60.4.103.25460.4.103.2552,046
14260.4.104.0/2160.4.104.1 to 60.4.111.25460.4.111.2552,046
14360.4.112.0/2160.4.112.1 to 60.4.119.25460.4.119.2552,046
14460.4.120.0/2160.4.120.1 to 60.4.127.25460.4.127.2552,046
14560.4.128.0/2160.4.128.1 to 60.4.135.25460.4.135.2552,046
14660.4.136.0/2160.4.136.1 to 60.4.143.25460.4.143.2552,046
14760.4.144.0/2160.4.144.1 to 60.4.151.25460.4.151.2552,046
14860.4.152.0/2160.4.152.1 to 60.4.159.25460.4.159.2552,046
14960.4.160.0/2160.4.160.1 to 60.4.167.25460.4.167.2552,046
15060.4.168.0/2160.4.168.1 to 60.4.175.25460.4.175.2552,046
15160.4.176.0/2160.4.176.1 to 60.4.183.25460.4.183.2552,046
15260.4.184.0/2160.4.184.1 to 60.4.191.25460.4.191.2552,046
15360.4.192.0/2160.4.192.1 to 60.4.199.25460.4.199.2552,046
15460.4.200.0/2160.4.200.1 to 60.4.207.25460.4.207.2552,046
15560.4.208.0/2160.4.208.1 to 60.4.215.25460.4.215.2552,046
15660.4.216.0/2160.4.216.1 to 60.4.223.25460.4.223.2552,046
15760.4.224.0/2160.4.224.1 to 60.4.231.25460.4.231.2552,046
15860.4.232.0/2160.4.232.1 to 60.4.239.25460.4.239.2552,046
15960.4.240.0/2160.4.240.1 to 60.4.247.25460.4.247.2552,046
16060.4.248.0/2160.4.248.1 to 60.4.255.25460.4.255.2552,046
16160.5.0.0/2160.5.0.1 to 60.5.7.25460.5.7.2552,046
16260.5.8.0/2160.5.8.1 to 60.5.15.25460.5.15.2552,046
16360.5.16.0/2160.5.16.1 to 60.5.23.25460.5.23.2552,046
16460.5.24.0/2160.5.24.1 to 60.5.31.25460.5.31.2552,046
16560.5.32.0/2160.5.32.1 to 60.5.39.25460.5.39.2552,046
16660.5.40.0/2160.5.40.1 to 60.5.47.25460.5.47.2552,046
16760.5.48.0/2160.5.48.1 to 60.5.55.25460.5.55.2552,046
16860.5.56.0/2160.5.56.1 to 60.5.63.25460.5.63.2552,046
16960.5.64.0/2160.5.64.1 to 60.5.71.25460.5.71.2552,046
17060.5.72.0/2160.5.72.1 to 60.5.79.25460.5.79.2552,046
17160.5.80.0/2160.5.80.1 to 60.5.87.25460.5.87.2552,046
17260.5.88.0/2160.5.88.1 to 60.5.95.25460.5.95.2552,046
17360.5.96.0/2160.5.96.1 to 60.5.103.25460.5.103.2552,046
17460.5.104.0/2160.5.104.1 to 60.5.111.25460.5.111.2552,046
17560.5.112.0/2160.5.112.1 to 60.5.119.25460.5.119.2552,046
17660.5.120.0/2160.5.120.1 to 60.5.127.25460.5.127.2552,046
17760.5.128.0/2160.5.128.1 to 60.5.135.25460.5.135.2552,046
17860.5.136.0/2160.5.136.1 to 60.5.143.25460.5.143.2552,046
17960.5.144.0/2160.5.144.1 to 60.5.151.25460.5.151.2552,046
18060.5.152.0/2160.5.152.1 to 60.5.159.25460.5.159.2552,046
18160.5.160.0/2160.5.160.1 to 60.5.167.25460.5.167.2552,046
18260.5.168.0/2160.5.168.1 to 60.5.175.25460.5.175.2552,046
18360.5.176.0/2160.5.176.1 to 60.5.183.25460.5.183.2552,046
18460.5.184.0/2160.5.184.1 to 60.5.191.25460.5.191.2552,046
18560.5.192.0/2160.5.192.1 to 60.5.199.25460.5.199.2552,046
18660.5.200.0/2160.5.200.1 to 60.5.207.25460.5.207.2552,046
18760.5.208.0/2160.5.208.1 to 60.5.215.25460.5.215.2552,046
18860.5.216.0/2160.5.216.1 to 60.5.223.25460.5.223.2552,046
18960.5.224.0/2160.5.224.1 to 60.5.231.25460.5.231.2552,046
19060.5.232.0/2160.5.232.1 to 60.5.239.25460.5.239.2552,046
19160.5.240.0/2160.5.240.1 to 60.5.247.25460.5.247.2552,046
19260.5.248.0/2160.5.248.1 to 60.5.255.25460.5.255.2552,046
19360.6.0.0/2160.6.0.1 to 60.6.7.25460.6.7.2552,046
19460.6.8.0/2160.6.8.1 to 60.6.15.25460.6.15.2552,046
19560.6.16.0/2160.6.16.1 to 60.6.23.25460.6.23.2552,046
19660.6.24.0/2160.6.24.1 to 60.6.31.25460.6.31.2552,046
19760.6.32.0/2160.6.32.1 to 60.6.39.25460.6.39.2552,046
19860.6.40.0/2160.6.40.1 to 60.6.47.25460.6.47.2552,046
19960.6.48.0/2160.6.48.1 to 60.6.55.25460.6.55.2552,046
20060.6.56.0/2160.6.56.1 to 60.6.63.25460.6.63.2552,046
20160.6.64.0/2160.6.64.1 to 60.6.71.25460.6.71.2552,046
20260.6.72.0/2160.6.72.1 to 60.6.79.25460.6.79.2552,046
20360.6.80.0/2160.6.80.1 to 60.6.87.25460.6.87.2552,046
20460.6.88.0/2160.6.88.1 to 60.6.95.25460.6.95.2552,046
20560.6.96.0/2160.6.96.1 to 60.6.103.25460.6.103.2552,046
20660.6.104.0/2160.6.104.1 to 60.6.111.25460.6.111.2552,046
20760.6.112.0/2160.6.112.1 to 60.6.119.25460.6.119.2552,046
20860.6.120.0/2160.6.120.1 to 60.6.127.25460.6.127.2552,046
20960.6.128.0/2160.6.128.1 to 60.6.135.25460.6.135.2552,046
21060.6.136.0/2160.6.136.1 to 60.6.143.25460.6.143.2552,046
21160.6.144.0/2160.6.144.1 to 60.6.151.25460.6.151.2552,046
21260.6.152.0/2160.6.152.1 to 60.6.159.25460.6.159.2552,046
21360.6.160.0/2160.6.160.1 to 60.6.167.25460.6.167.2552,046
21460.6.168.0/2160.6.168.1 to 60.6.175.25460.6.175.2552,046
21560.6.176.0/2160.6.176.1 to 60.6.183.25460.6.183.2552,046
21660.6.184.0/2160.6.184.1 to 60.6.191.25460.6.191.2552,046
21760.6.192.0/2160.6.192.1 to 60.6.199.25460.6.199.2552,046
21860.6.200.0/2160.6.200.1 to 60.6.207.25460.6.207.2552,046
21960.6.208.0/2160.6.208.1 to 60.6.215.25460.6.215.2552,046
22060.6.216.0/2160.6.216.1 to 60.6.223.25460.6.223.2552,046
22160.6.224.0/2160.6.224.1 to 60.6.231.25460.6.231.2552,046
22260.6.232.0/2160.6.232.1 to 60.6.239.25460.6.239.2552,046
22360.6.240.0/2160.6.240.1 to 60.6.247.25460.6.247.2552,046
22460.6.248.0/2160.6.248.1 to 60.6.255.25460.6.255.2552,046
22560.7.0.0/2160.7.0.1 to 60.7.7.25460.7.7.2552,046
22660.7.8.0/2160.7.8.1 to 60.7.15.25460.7.15.2552,046
22760.7.16.0/2160.7.16.1 to 60.7.23.25460.7.23.2552,046
22860.7.24.0/2160.7.24.1 to 60.7.31.25460.7.31.2552,046
22960.7.32.0/2160.7.32.1 to 60.7.39.25460.7.39.2552,046
23060.7.40.0/2160.7.40.1 to 60.7.47.25460.7.47.2552,046
23160.7.48.0/2160.7.48.1 to 60.7.55.25460.7.55.2552,046
23260.7.56.0/2160.7.56.1 to 60.7.63.25460.7.63.2552,046
23360.7.64.0/2160.7.64.1 to 60.7.71.25460.7.71.2552,046
23460.7.72.0/2160.7.72.1 to 60.7.79.25460.7.79.2552,046
23560.7.80.0/2160.7.80.1 to 60.7.87.25460.7.87.2552,046
23660.7.88.0/2160.7.88.1 to 60.7.95.25460.7.95.2552,046
23760.7.96.0/2160.7.96.1 to 60.7.103.25460.7.103.2552,046
23860.7.104.0/2160.7.104.1 to 60.7.111.25460.7.111.2552,046
23960.7.112.0/2160.7.112.1 to 60.7.119.25460.7.119.2552,046
24060.7.120.0/2160.7.120.1 to 60.7.127.25460.7.127.2552,046
24160.7.128.0/2160.7.128.1 to 60.7.135.25460.7.135.2552,046
24260.7.136.0/2160.7.136.1 to 60.7.143.25460.7.143.2552,046
24360.7.144.0/2160.7.144.1 to 60.7.151.25460.7.151.2552,046
24460.7.152.0/2160.7.152.1 to 60.7.159.25460.7.159.2552,046
24560.7.160.0/2160.7.160.1 to 60.7.167.25460.7.167.2552,046
24660.7.168.0/2160.7.168.1 to 60.7.175.25460.7.175.2552,046
24760.7.176.0/2160.7.176.1 to 60.7.183.25460.7.183.2552,046
24860.7.184.0/2160.7.184.1 to 60.7.191.25460.7.191.2552,046
24960.7.192.0/2160.7.192.1 to 60.7.199.25460.7.199.2552,046
25060.7.200.0/2160.7.200.1 to 60.7.207.25460.7.207.2552,046
25160.7.208.0/2160.7.208.1 to 60.7.215.25460.7.215.2552,046
25260.7.216.0/2160.7.216.1 to 60.7.223.25460.7.223.2552,046
25360.7.224.0/2160.7.224.1 to 60.7.231.25460.7.231.2552,046
25460.7.232.0/2160.7.232.1 to 60.7.239.25460.7.239.2552,046
25560.7.240.0/2160.7.240.1 to 60.7.247.25460.7.247.2552,046
25660.7.248.0/2160.7.248.1 to 60.7.255.25460.7.255.2552,046

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.