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.

Network35.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
35.0.0.0
Broadcast address
35.255.255.255
First usable
35.0.0.1
Last usable
35.255.255.254
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 23000000 · Integer 587202560 to 603979775
Reverse DNS zone
35.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00100011..00000000.00000000.0000000035.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00100011..00000000.00000000.0000000035.0.0.0
Broadcast00100011..11111111.11111111.1111111135.255.255.255
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)

35.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
135.0.0.0/2035.0.0.1 to 35.0.15.25435.0.15.2554,094
235.0.16.0/2035.0.16.1 to 35.0.31.25435.0.31.2554,094
335.0.32.0/2035.0.32.1 to 35.0.47.25435.0.47.2554,094
435.0.48.0/2035.0.48.1 to 35.0.63.25435.0.63.2554,094
535.0.64.0/2035.0.64.1 to 35.0.79.25435.0.79.2554,094
635.0.80.0/2035.0.80.1 to 35.0.95.25435.0.95.2554,094
735.0.96.0/2035.0.96.1 to 35.0.111.25435.0.111.2554,094
835.0.112.0/2035.0.112.1 to 35.0.127.25435.0.127.2554,094
935.0.128.0/2035.0.128.1 to 35.0.143.25435.0.143.2554,094
1035.0.144.0/2035.0.144.1 to 35.0.159.25435.0.159.2554,094
1135.0.160.0/2035.0.160.1 to 35.0.175.25435.0.175.2554,094
1235.0.176.0/2035.0.176.1 to 35.0.191.25435.0.191.2554,094
1335.0.192.0/2035.0.192.1 to 35.0.207.25435.0.207.2554,094
1435.0.208.0/2035.0.208.1 to 35.0.223.25435.0.223.2554,094
1535.0.224.0/2035.0.224.1 to 35.0.239.25435.0.239.2554,094
1635.0.240.0/2035.0.240.1 to 35.0.255.25435.0.255.2554,094
1735.1.0.0/2035.1.0.1 to 35.1.15.25435.1.15.2554,094
1835.1.16.0/2035.1.16.1 to 35.1.31.25435.1.31.2554,094
1935.1.32.0/2035.1.32.1 to 35.1.47.25435.1.47.2554,094
2035.1.48.0/2035.1.48.1 to 35.1.63.25435.1.63.2554,094
2135.1.64.0/2035.1.64.1 to 35.1.79.25435.1.79.2554,094
2235.1.80.0/2035.1.80.1 to 35.1.95.25435.1.95.2554,094
2335.1.96.0/2035.1.96.1 to 35.1.111.25435.1.111.2554,094
2435.1.112.0/2035.1.112.1 to 35.1.127.25435.1.127.2554,094
2535.1.128.0/2035.1.128.1 to 35.1.143.25435.1.143.2554,094
2635.1.144.0/2035.1.144.1 to 35.1.159.25435.1.159.2554,094
2735.1.160.0/2035.1.160.1 to 35.1.175.25435.1.175.2554,094
2835.1.176.0/2035.1.176.1 to 35.1.191.25435.1.191.2554,094
2935.1.192.0/2035.1.192.1 to 35.1.207.25435.1.207.2554,094
3035.1.208.0/2035.1.208.1 to 35.1.223.25435.1.223.2554,094
3135.1.224.0/2035.1.224.1 to 35.1.239.25435.1.239.2554,094
3235.1.240.0/2035.1.240.1 to 35.1.255.25435.1.255.2554,094
3335.2.0.0/2035.2.0.1 to 35.2.15.25435.2.15.2554,094
3435.2.16.0/2035.2.16.1 to 35.2.31.25435.2.31.2554,094
3535.2.32.0/2035.2.32.1 to 35.2.47.25435.2.47.2554,094
3635.2.48.0/2035.2.48.1 to 35.2.63.25435.2.63.2554,094
3735.2.64.0/2035.2.64.1 to 35.2.79.25435.2.79.2554,094
3835.2.80.0/2035.2.80.1 to 35.2.95.25435.2.95.2554,094
3935.2.96.0/2035.2.96.1 to 35.2.111.25435.2.111.2554,094
4035.2.112.0/2035.2.112.1 to 35.2.127.25435.2.127.2554,094
4135.2.128.0/2035.2.128.1 to 35.2.143.25435.2.143.2554,094
4235.2.144.0/2035.2.144.1 to 35.2.159.25435.2.159.2554,094
4335.2.160.0/2035.2.160.1 to 35.2.175.25435.2.175.2554,094
4435.2.176.0/2035.2.176.1 to 35.2.191.25435.2.191.2554,094
4535.2.192.0/2035.2.192.1 to 35.2.207.25435.2.207.2554,094
4635.2.208.0/2035.2.208.1 to 35.2.223.25435.2.223.2554,094
4735.2.224.0/2035.2.224.1 to 35.2.239.25435.2.239.2554,094
4835.2.240.0/2035.2.240.1 to 35.2.255.25435.2.255.2554,094
4935.3.0.0/2035.3.0.1 to 35.3.15.25435.3.15.2554,094
5035.3.16.0/2035.3.16.1 to 35.3.31.25435.3.31.2554,094
5135.3.32.0/2035.3.32.1 to 35.3.47.25435.3.47.2554,094
5235.3.48.0/2035.3.48.1 to 35.3.63.25435.3.63.2554,094
5335.3.64.0/2035.3.64.1 to 35.3.79.25435.3.79.2554,094
5435.3.80.0/2035.3.80.1 to 35.3.95.25435.3.95.2554,094
5535.3.96.0/2035.3.96.1 to 35.3.111.25435.3.111.2554,094
5635.3.112.0/2035.3.112.1 to 35.3.127.25435.3.127.2554,094
5735.3.128.0/2035.3.128.1 to 35.3.143.25435.3.143.2554,094
5835.3.144.0/2035.3.144.1 to 35.3.159.25435.3.159.2554,094
5935.3.160.0/2035.3.160.1 to 35.3.175.25435.3.175.2554,094
6035.3.176.0/2035.3.176.1 to 35.3.191.25435.3.191.2554,094
6135.3.192.0/2035.3.192.1 to 35.3.207.25435.3.207.2554,094
6235.3.208.0/2035.3.208.1 to 35.3.223.25435.3.223.2554,094
6335.3.224.0/2035.3.224.1 to 35.3.239.25435.3.239.2554,094
6435.3.240.0/2035.3.240.1 to 35.3.255.25435.3.255.2554,094
6535.4.0.0/2035.4.0.1 to 35.4.15.25435.4.15.2554,094
6635.4.16.0/2035.4.16.1 to 35.4.31.25435.4.31.2554,094
6735.4.32.0/2035.4.32.1 to 35.4.47.25435.4.47.2554,094
6835.4.48.0/2035.4.48.1 to 35.4.63.25435.4.63.2554,094
6935.4.64.0/2035.4.64.1 to 35.4.79.25435.4.79.2554,094
7035.4.80.0/2035.4.80.1 to 35.4.95.25435.4.95.2554,094
7135.4.96.0/2035.4.96.1 to 35.4.111.25435.4.111.2554,094
7235.4.112.0/2035.4.112.1 to 35.4.127.25435.4.127.2554,094
7335.4.128.0/2035.4.128.1 to 35.4.143.25435.4.143.2554,094
7435.4.144.0/2035.4.144.1 to 35.4.159.25435.4.159.2554,094
7535.4.160.0/2035.4.160.1 to 35.4.175.25435.4.175.2554,094
7635.4.176.0/2035.4.176.1 to 35.4.191.25435.4.191.2554,094
7735.4.192.0/2035.4.192.1 to 35.4.207.25435.4.207.2554,094
7835.4.208.0/2035.4.208.1 to 35.4.223.25435.4.223.2554,094
7935.4.224.0/2035.4.224.1 to 35.4.239.25435.4.239.2554,094
8035.4.240.0/2035.4.240.1 to 35.4.255.25435.4.255.2554,094
8135.5.0.0/2035.5.0.1 to 35.5.15.25435.5.15.2554,094
8235.5.16.0/2035.5.16.1 to 35.5.31.25435.5.31.2554,094
8335.5.32.0/2035.5.32.1 to 35.5.47.25435.5.47.2554,094
8435.5.48.0/2035.5.48.1 to 35.5.63.25435.5.63.2554,094
8535.5.64.0/2035.5.64.1 to 35.5.79.25435.5.79.2554,094
8635.5.80.0/2035.5.80.1 to 35.5.95.25435.5.95.2554,094
8735.5.96.0/2035.5.96.1 to 35.5.111.25435.5.111.2554,094
8835.5.112.0/2035.5.112.1 to 35.5.127.25435.5.127.2554,094
8935.5.128.0/2035.5.128.1 to 35.5.143.25435.5.143.2554,094
9035.5.144.0/2035.5.144.1 to 35.5.159.25435.5.159.2554,094
9135.5.160.0/2035.5.160.1 to 35.5.175.25435.5.175.2554,094
9235.5.176.0/2035.5.176.1 to 35.5.191.25435.5.191.2554,094
9335.5.192.0/2035.5.192.1 to 35.5.207.25435.5.207.2554,094
9435.5.208.0/2035.5.208.1 to 35.5.223.25435.5.223.2554,094
9535.5.224.0/2035.5.224.1 to 35.5.239.25435.5.239.2554,094
9635.5.240.0/2035.5.240.1 to 35.5.255.25435.5.255.2554,094
9735.6.0.0/2035.6.0.1 to 35.6.15.25435.6.15.2554,094
9835.6.16.0/2035.6.16.1 to 35.6.31.25435.6.31.2554,094
9935.6.32.0/2035.6.32.1 to 35.6.47.25435.6.47.2554,094
10035.6.48.0/2035.6.48.1 to 35.6.63.25435.6.63.2554,094
10135.6.64.0/2035.6.64.1 to 35.6.79.25435.6.79.2554,094
10235.6.80.0/2035.6.80.1 to 35.6.95.25435.6.95.2554,094
10335.6.96.0/2035.6.96.1 to 35.6.111.25435.6.111.2554,094
10435.6.112.0/2035.6.112.1 to 35.6.127.25435.6.127.2554,094
10535.6.128.0/2035.6.128.1 to 35.6.143.25435.6.143.2554,094
10635.6.144.0/2035.6.144.1 to 35.6.159.25435.6.159.2554,094
10735.6.160.0/2035.6.160.1 to 35.6.175.25435.6.175.2554,094
10835.6.176.0/2035.6.176.1 to 35.6.191.25435.6.191.2554,094
10935.6.192.0/2035.6.192.1 to 35.6.207.25435.6.207.2554,094
11035.6.208.0/2035.6.208.1 to 35.6.223.25435.6.223.2554,094
11135.6.224.0/2035.6.224.1 to 35.6.239.25435.6.239.2554,094
11235.6.240.0/2035.6.240.1 to 35.6.255.25435.6.255.2554,094
11335.7.0.0/2035.7.0.1 to 35.7.15.25435.7.15.2554,094
11435.7.16.0/2035.7.16.1 to 35.7.31.25435.7.31.2554,094
11535.7.32.0/2035.7.32.1 to 35.7.47.25435.7.47.2554,094
11635.7.48.0/2035.7.48.1 to 35.7.63.25435.7.63.2554,094
11735.7.64.0/2035.7.64.1 to 35.7.79.25435.7.79.2554,094
11835.7.80.0/2035.7.80.1 to 35.7.95.25435.7.95.2554,094
11935.7.96.0/2035.7.96.1 to 35.7.111.25435.7.111.2554,094
12035.7.112.0/2035.7.112.1 to 35.7.127.25435.7.127.2554,094
12135.7.128.0/2035.7.128.1 to 35.7.143.25435.7.143.2554,094
12235.7.144.0/2035.7.144.1 to 35.7.159.25435.7.159.2554,094
12335.7.160.0/2035.7.160.1 to 35.7.175.25435.7.175.2554,094
12435.7.176.0/2035.7.176.1 to 35.7.191.25435.7.191.2554,094
12535.7.192.0/2035.7.192.1 to 35.7.207.25435.7.207.2554,094
12635.7.208.0/2035.7.208.1 to 35.7.223.25435.7.223.2554,094
12735.7.224.0/2035.7.224.1 to 35.7.239.25435.7.239.2554,094
12835.7.240.0/2035.7.240.1 to 35.7.255.25435.7.255.2554,094
12935.8.0.0/2035.8.0.1 to 35.8.15.25435.8.15.2554,094
13035.8.16.0/2035.8.16.1 to 35.8.31.25435.8.31.2554,094
13135.8.32.0/2035.8.32.1 to 35.8.47.25435.8.47.2554,094
13235.8.48.0/2035.8.48.1 to 35.8.63.25435.8.63.2554,094
13335.8.64.0/2035.8.64.1 to 35.8.79.25435.8.79.2554,094
13435.8.80.0/2035.8.80.1 to 35.8.95.25435.8.95.2554,094
13535.8.96.0/2035.8.96.1 to 35.8.111.25435.8.111.2554,094
13635.8.112.0/2035.8.112.1 to 35.8.127.25435.8.127.2554,094
13735.8.128.0/2035.8.128.1 to 35.8.143.25435.8.143.2554,094
13835.8.144.0/2035.8.144.1 to 35.8.159.25435.8.159.2554,094
13935.8.160.0/2035.8.160.1 to 35.8.175.25435.8.175.2554,094
14035.8.176.0/2035.8.176.1 to 35.8.191.25435.8.191.2554,094
14135.8.192.0/2035.8.192.1 to 35.8.207.25435.8.207.2554,094
14235.8.208.0/2035.8.208.1 to 35.8.223.25435.8.223.2554,094
14335.8.224.0/2035.8.224.1 to 35.8.239.25435.8.239.2554,094
14435.8.240.0/2035.8.240.1 to 35.8.255.25435.8.255.2554,094
14535.9.0.0/2035.9.0.1 to 35.9.15.25435.9.15.2554,094
14635.9.16.0/2035.9.16.1 to 35.9.31.25435.9.31.2554,094
14735.9.32.0/2035.9.32.1 to 35.9.47.25435.9.47.2554,094
14835.9.48.0/2035.9.48.1 to 35.9.63.25435.9.63.2554,094
14935.9.64.0/2035.9.64.1 to 35.9.79.25435.9.79.2554,094
15035.9.80.0/2035.9.80.1 to 35.9.95.25435.9.95.2554,094
15135.9.96.0/2035.9.96.1 to 35.9.111.25435.9.111.2554,094
15235.9.112.0/2035.9.112.1 to 35.9.127.25435.9.127.2554,094
15335.9.128.0/2035.9.128.1 to 35.9.143.25435.9.143.2554,094
15435.9.144.0/2035.9.144.1 to 35.9.159.25435.9.159.2554,094
15535.9.160.0/2035.9.160.1 to 35.9.175.25435.9.175.2554,094
15635.9.176.0/2035.9.176.1 to 35.9.191.25435.9.191.2554,094
15735.9.192.0/2035.9.192.1 to 35.9.207.25435.9.207.2554,094
15835.9.208.0/2035.9.208.1 to 35.9.223.25435.9.223.2554,094
15935.9.224.0/2035.9.224.1 to 35.9.239.25435.9.239.2554,094
16035.9.240.0/2035.9.240.1 to 35.9.255.25435.9.255.2554,094
16135.10.0.0/2035.10.0.1 to 35.10.15.25435.10.15.2554,094
16235.10.16.0/2035.10.16.1 to 35.10.31.25435.10.31.2554,094
16335.10.32.0/2035.10.32.1 to 35.10.47.25435.10.47.2554,094
16435.10.48.0/2035.10.48.1 to 35.10.63.25435.10.63.2554,094
16535.10.64.0/2035.10.64.1 to 35.10.79.25435.10.79.2554,094
16635.10.80.0/2035.10.80.1 to 35.10.95.25435.10.95.2554,094
16735.10.96.0/2035.10.96.1 to 35.10.111.25435.10.111.2554,094
16835.10.112.0/2035.10.112.1 to 35.10.127.25435.10.127.2554,094
16935.10.128.0/2035.10.128.1 to 35.10.143.25435.10.143.2554,094
17035.10.144.0/2035.10.144.1 to 35.10.159.25435.10.159.2554,094
17135.10.160.0/2035.10.160.1 to 35.10.175.25435.10.175.2554,094
17235.10.176.0/2035.10.176.1 to 35.10.191.25435.10.191.2554,094
17335.10.192.0/2035.10.192.1 to 35.10.207.25435.10.207.2554,094
17435.10.208.0/2035.10.208.1 to 35.10.223.25435.10.223.2554,094
17535.10.224.0/2035.10.224.1 to 35.10.239.25435.10.239.2554,094
17635.10.240.0/2035.10.240.1 to 35.10.255.25435.10.255.2554,094
17735.11.0.0/2035.11.0.1 to 35.11.15.25435.11.15.2554,094
17835.11.16.0/2035.11.16.1 to 35.11.31.25435.11.31.2554,094
17935.11.32.0/2035.11.32.1 to 35.11.47.25435.11.47.2554,094
18035.11.48.0/2035.11.48.1 to 35.11.63.25435.11.63.2554,094
18135.11.64.0/2035.11.64.1 to 35.11.79.25435.11.79.2554,094
18235.11.80.0/2035.11.80.1 to 35.11.95.25435.11.95.2554,094
18335.11.96.0/2035.11.96.1 to 35.11.111.25435.11.111.2554,094
18435.11.112.0/2035.11.112.1 to 35.11.127.25435.11.127.2554,094
18535.11.128.0/2035.11.128.1 to 35.11.143.25435.11.143.2554,094
18635.11.144.0/2035.11.144.1 to 35.11.159.25435.11.159.2554,094
18735.11.160.0/2035.11.160.1 to 35.11.175.25435.11.175.2554,094
18835.11.176.0/2035.11.176.1 to 35.11.191.25435.11.191.2554,094
18935.11.192.0/2035.11.192.1 to 35.11.207.25435.11.207.2554,094
19035.11.208.0/2035.11.208.1 to 35.11.223.25435.11.223.2554,094
19135.11.224.0/2035.11.224.1 to 35.11.239.25435.11.239.2554,094
19235.11.240.0/2035.11.240.1 to 35.11.255.25435.11.255.2554,094
19335.12.0.0/2035.12.0.1 to 35.12.15.25435.12.15.2554,094
19435.12.16.0/2035.12.16.1 to 35.12.31.25435.12.31.2554,094
19535.12.32.0/2035.12.32.1 to 35.12.47.25435.12.47.2554,094
19635.12.48.0/2035.12.48.1 to 35.12.63.25435.12.63.2554,094
19735.12.64.0/2035.12.64.1 to 35.12.79.25435.12.79.2554,094
19835.12.80.0/2035.12.80.1 to 35.12.95.25435.12.95.2554,094
19935.12.96.0/2035.12.96.1 to 35.12.111.25435.12.111.2554,094
20035.12.112.0/2035.12.112.1 to 35.12.127.25435.12.127.2554,094
20135.12.128.0/2035.12.128.1 to 35.12.143.25435.12.143.2554,094
20235.12.144.0/2035.12.144.1 to 35.12.159.25435.12.159.2554,094
20335.12.160.0/2035.12.160.1 to 35.12.175.25435.12.175.2554,094
20435.12.176.0/2035.12.176.1 to 35.12.191.25435.12.191.2554,094
20535.12.192.0/2035.12.192.1 to 35.12.207.25435.12.207.2554,094
20635.12.208.0/2035.12.208.1 to 35.12.223.25435.12.223.2554,094
20735.12.224.0/2035.12.224.1 to 35.12.239.25435.12.239.2554,094
20835.12.240.0/2035.12.240.1 to 35.12.255.25435.12.255.2554,094
20935.13.0.0/2035.13.0.1 to 35.13.15.25435.13.15.2554,094
21035.13.16.0/2035.13.16.1 to 35.13.31.25435.13.31.2554,094
21135.13.32.0/2035.13.32.1 to 35.13.47.25435.13.47.2554,094
21235.13.48.0/2035.13.48.1 to 35.13.63.25435.13.63.2554,094
21335.13.64.0/2035.13.64.1 to 35.13.79.25435.13.79.2554,094
21435.13.80.0/2035.13.80.1 to 35.13.95.25435.13.95.2554,094
21535.13.96.0/2035.13.96.1 to 35.13.111.25435.13.111.2554,094
21635.13.112.0/2035.13.112.1 to 35.13.127.25435.13.127.2554,094
21735.13.128.0/2035.13.128.1 to 35.13.143.25435.13.143.2554,094
21835.13.144.0/2035.13.144.1 to 35.13.159.25435.13.159.2554,094
21935.13.160.0/2035.13.160.1 to 35.13.175.25435.13.175.2554,094
22035.13.176.0/2035.13.176.1 to 35.13.191.25435.13.191.2554,094
22135.13.192.0/2035.13.192.1 to 35.13.207.25435.13.207.2554,094
22235.13.208.0/2035.13.208.1 to 35.13.223.25435.13.223.2554,094
22335.13.224.0/2035.13.224.1 to 35.13.239.25435.13.239.2554,094
22435.13.240.0/2035.13.240.1 to 35.13.255.25435.13.255.2554,094
22535.14.0.0/2035.14.0.1 to 35.14.15.25435.14.15.2554,094
22635.14.16.0/2035.14.16.1 to 35.14.31.25435.14.31.2554,094
22735.14.32.0/2035.14.32.1 to 35.14.47.25435.14.47.2554,094
22835.14.48.0/2035.14.48.1 to 35.14.63.25435.14.63.2554,094
22935.14.64.0/2035.14.64.1 to 35.14.79.25435.14.79.2554,094
23035.14.80.0/2035.14.80.1 to 35.14.95.25435.14.95.2554,094
23135.14.96.0/2035.14.96.1 to 35.14.111.25435.14.111.2554,094
23235.14.112.0/2035.14.112.1 to 35.14.127.25435.14.127.2554,094
23335.14.128.0/2035.14.128.1 to 35.14.143.25435.14.143.2554,094
23435.14.144.0/2035.14.144.1 to 35.14.159.25435.14.159.2554,094
23535.14.160.0/2035.14.160.1 to 35.14.175.25435.14.175.2554,094
23635.14.176.0/2035.14.176.1 to 35.14.191.25435.14.191.2554,094
23735.14.192.0/2035.14.192.1 to 35.14.207.25435.14.207.2554,094
23835.14.208.0/2035.14.208.1 to 35.14.223.25435.14.223.2554,094
23935.14.224.0/2035.14.224.1 to 35.14.239.25435.14.239.2554,094
24035.14.240.0/2035.14.240.1 to 35.14.255.25435.14.255.2554,094
24135.15.0.0/2035.15.0.1 to 35.15.15.25435.15.15.2554,094
24235.15.16.0/2035.15.16.1 to 35.15.31.25435.15.31.2554,094
24335.15.32.0/2035.15.32.1 to 35.15.47.25435.15.47.2554,094
24435.15.48.0/2035.15.48.1 to 35.15.63.25435.15.63.2554,094
24535.15.64.0/2035.15.64.1 to 35.15.79.25435.15.79.2554,094
24635.15.80.0/2035.15.80.1 to 35.15.95.25435.15.95.2554,094
24735.15.96.0/2035.15.96.1 to 35.15.111.25435.15.111.2554,094
24835.15.112.0/2035.15.112.1 to 35.15.127.25435.15.127.2554,094
24935.15.128.0/2035.15.128.1 to 35.15.143.25435.15.143.2554,094
25035.15.144.0/2035.15.144.1 to 35.15.159.25435.15.159.2554,094
25135.15.160.0/2035.15.160.1 to 35.15.175.25435.15.175.2554,094
25235.15.176.0/2035.15.176.1 to 35.15.191.25435.15.191.2554,094
25335.15.192.0/2035.15.192.1 to 35.15.207.25435.15.207.2554,094
25435.15.208.0/2035.15.208.1 to 35.15.223.25435.15.223.2554,094
25535.15.224.0/2035.15.224.1 to 35.15.239.25435.15.239.2554,094
25635.15.240.0/2035.15.240.1 to 35.15.255.25435.15.255.2554,094

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.