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.

Network50.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
50.0.0.0
Broadcast address
50.255.255.255
First usable
50.0.0.1
Last usable
50.255.255.254
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 32000000 · Integer 838860800 to 855638015
Reverse DNS zone
50.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00110010..00000000.00000000.0000000050.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00110010..00000000.00000000.0000000050.0.0.0
Broadcast00110010..11111111.11111111.1111111150.255.255.255
Split into smaller subnets/19
/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)

50.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
150.0.0.0/1950.0.0.1 to 50.0.31.25450.0.31.2558,190
250.0.32.0/1950.0.32.1 to 50.0.63.25450.0.63.2558,190
350.0.64.0/1950.0.64.1 to 50.0.95.25450.0.95.2558,190
450.0.96.0/1950.0.96.1 to 50.0.127.25450.0.127.2558,190
550.0.128.0/1950.0.128.1 to 50.0.159.25450.0.159.2558,190
650.0.160.0/1950.0.160.1 to 50.0.191.25450.0.191.2558,190
750.0.192.0/1950.0.192.1 to 50.0.223.25450.0.223.2558,190
850.0.224.0/1950.0.224.1 to 50.0.255.25450.0.255.2558,190
950.1.0.0/1950.1.0.1 to 50.1.31.25450.1.31.2558,190
1050.1.32.0/1950.1.32.1 to 50.1.63.25450.1.63.2558,190
1150.1.64.0/1950.1.64.1 to 50.1.95.25450.1.95.2558,190
1250.1.96.0/1950.1.96.1 to 50.1.127.25450.1.127.2558,190
1350.1.128.0/1950.1.128.1 to 50.1.159.25450.1.159.2558,190
1450.1.160.0/1950.1.160.1 to 50.1.191.25450.1.191.2558,190
1550.1.192.0/1950.1.192.1 to 50.1.223.25450.1.223.2558,190
1650.1.224.0/1950.1.224.1 to 50.1.255.25450.1.255.2558,190
1750.2.0.0/1950.2.0.1 to 50.2.31.25450.2.31.2558,190
1850.2.32.0/1950.2.32.1 to 50.2.63.25450.2.63.2558,190
1950.2.64.0/1950.2.64.1 to 50.2.95.25450.2.95.2558,190
2050.2.96.0/1950.2.96.1 to 50.2.127.25450.2.127.2558,190
2150.2.128.0/1950.2.128.1 to 50.2.159.25450.2.159.2558,190
2250.2.160.0/1950.2.160.1 to 50.2.191.25450.2.191.2558,190
2350.2.192.0/1950.2.192.1 to 50.2.223.25450.2.223.2558,190
2450.2.224.0/1950.2.224.1 to 50.2.255.25450.2.255.2558,190
2550.3.0.0/1950.3.0.1 to 50.3.31.25450.3.31.2558,190
2650.3.32.0/1950.3.32.1 to 50.3.63.25450.3.63.2558,190
2750.3.64.0/1950.3.64.1 to 50.3.95.25450.3.95.2558,190
2850.3.96.0/1950.3.96.1 to 50.3.127.25450.3.127.2558,190
2950.3.128.0/1950.3.128.1 to 50.3.159.25450.3.159.2558,190
3050.3.160.0/1950.3.160.1 to 50.3.191.25450.3.191.2558,190
3150.3.192.0/1950.3.192.1 to 50.3.223.25450.3.223.2558,190
3250.3.224.0/1950.3.224.1 to 50.3.255.25450.3.255.2558,190
3350.4.0.0/1950.4.0.1 to 50.4.31.25450.4.31.2558,190
3450.4.32.0/1950.4.32.1 to 50.4.63.25450.4.63.2558,190
3550.4.64.0/1950.4.64.1 to 50.4.95.25450.4.95.2558,190
3650.4.96.0/1950.4.96.1 to 50.4.127.25450.4.127.2558,190
3750.4.128.0/1950.4.128.1 to 50.4.159.25450.4.159.2558,190
3850.4.160.0/1950.4.160.1 to 50.4.191.25450.4.191.2558,190
3950.4.192.0/1950.4.192.1 to 50.4.223.25450.4.223.2558,190
4050.4.224.0/1950.4.224.1 to 50.4.255.25450.4.255.2558,190
4150.5.0.0/1950.5.0.1 to 50.5.31.25450.5.31.2558,190
4250.5.32.0/1950.5.32.1 to 50.5.63.25450.5.63.2558,190
4350.5.64.0/1950.5.64.1 to 50.5.95.25450.5.95.2558,190
4450.5.96.0/1950.5.96.1 to 50.5.127.25450.5.127.2558,190
4550.5.128.0/1950.5.128.1 to 50.5.159.25450.5.159.2558,190
4650.5.160.0/1950.5.160.1 to 50.5.191.25450.5.191.2558,190
4750.5.192.0/1950.5.192.1 to 50.5.223.25450.5.223.2558,190
4850.5.224.0/1950.5.224.1 to 50.5.255.25450.5.255.2558,190
4950.6.0.0/1950.6.0.1 to 50.6.31.25450.6.31.2558,190
5050.6.32.0/1950.6.32.1 to 50.6.63.25450.6.63.2558,190
5150.6.64.0/1950.6.64.1 to 50.6.95.25450.6.95.2558,190
5250.6.96.0/1950.6.96.1 to 50.6.127.25450.6.127.2558,190
5350.6.128.0/1950.6.128.1 to 50.6.159.25450.6.159.2558,190
5450.6.160.0/1950.6.160.1 to 50.6.191.25450.6.191.2558,190
5550.6.192.0/1950.6.192.1 to 50.6.223.25450.6.223.2558,190
5650.6.224.0/1950.6.224.1 to 50.6.255.25450.6.255.2558,190
5750.7.0.0/1950.7.0.1 to 50.7.31.25450.7.31.2558,190
5850.7.32.0/1950.7.32.1 to 50.7.63.25450.7.63.2558,190
5950.7.64.0/1950.7.64.1 to 50.7.95.25450.7.95.2558,190
6050.7.96.0/1950.7.96.1 to 50.7.127.25450.7.127.2558,190
6150.7.128.0/1950.7.128.1 to 50.7.159.25450.7.159.2558,190
6250.7.160.0/1950.7.160.1 to 50.7.191.25450.7.191.2558,190
6350.7.192.0/1950.7.192.1 to 50.7.223.25450.7.223.2558,190
6450.7.224.0/1950.7.224.1 to 50.7.255.25450.7.255.2558,190
6550.8.0.0/1950.8.0.1 to 50.8.31.25450.8.31.2558,190
6650.8.32.0/1950.8.32.1 to 50.8.63.25450.8.63.2558,190
6750.8.64.0/1950.8.64.1 to 50.8.95.25450.8.95.2558,190
6850.8.96.0/1950.8.96.1 to 50.8.127.25450.8.127.2558,190
6950.8.128.0/1950.8.128.1 to 50.8.159.25450.8.159.2558,190
7050.8.160.0/1950.8.160.1 to 50.8.191.25450.8.191.2558,190
7150.8.192.0/1950.8.192.1 to 50.8.223.25450.8.223.2558,190
7250.8.224.0/1950.8.224.1 to 50.8.255.25450.8.255.2558,190
7350.9.0.0/1950.9.0.1 to 50.9.31.25450.9.31.2558,190
7450.9.32.0/1950.9.32.1 to 50.9.63.25450.9.63.2558,190
7550.9.64.0/1950.9.64.1 to 50.9.95.25450.9.95.2558,190
7650.9.96.0/1950.9.96.1 to 50.9.127.25450.9.127.2558,190
7750.9.128.0/1950.9.128.1 to 50.9.159.25450.9.159.2558,190
7850.9.160.0/1950.9.160.1 to 50.9.191.25450.9.191.2558,190
7950.9.192.0/1950.9.192.1 to 50.9.223.25450.9.223.2558,190
8050.9.224.0/1950.9.224.1 to 50.9.255.25450.9.255.2558,190
8150.10.0.0/1950.10.0.1 to 50.10.31.25450.10.31.2558,190
8250.10.32.0/1950.10.32.1 to 50.10.63.25450.10.63.2558,190
8350.10.64.0/1950.10.64.1 to 50.10.95.25450.10.95.2558,190
8450.10.96.0/1950.10.96.1 to 50.10.127.25450.10.127.2558,190
8550.10.128.0/1950.10.128.1 to 50.10.159.25450.10.159.2558,190
8650.10.160.0/1950.10.160.1 to 50.10.191.25450.10.191.2558,190
8750.10.192.0/1950.10.192.1 to 50.10.223.25450.10.223.2558,190
8850.10.224.0/1950.10.224.1 to 50.10.255.25450.10.255.2558,190
8950.11.0.0/1950.11.0.1 to 50.11.31.25450.11.31.2558,190
9050.11.32.0/1950.11.32.1 to 50.11.63.25450.11.63.2558,190
9150.11.64.0/1950.11.64.1 to 50.11.95.25450.11.95.2558,190
9250.11.96.0/1950.11.96.1 to 50.11.127.25450.11.127.2558,190
9350.11.128.0/1950.11.128.1 to 50.11.159.25450.11.159.2558,190
9450.11.160.0/1950.11.160.1 to 50.11.191.25450.11.191.2558,190
9550.11.192.0/1950.11.192.1 to 50.11.223.25450.11.223.2558,190
9650.11.224.0/1950.11.224.1 to 50.11.255.25450.11.255.2558,190
9750.12.0.0/1950.12.0.1 to 50.12.31.25450.12.31.2558,190
9850.12.32.0/1950.12.32.1 to 50.12.63.25450.12.63.2558,190
9950.12.64.0/1950.12.64.1 to 50.12.95.25450.12.95.2558,190
10050.12.96.0/1950.12.96.1 to 50.12.127.25450.12.127.2558,190
10150.12.128.0/1950.12.128.1 to 50.12.159.25450.12.159.2558,190
10250.12.160.0/1950.12.160.1 to 50.12.191.25450.12.191.2558,190
10350.12.192.0/1950.12.192.1 to 50.12.223.25450.12.223.2558,190
10450.12.224.0/1950.12.224.1 to 50.12.255.25450.12.255.2558,190
10550.13.0.0/1950.13.0.1 to 50.13.31.25450.13.31.2558,190
10650.13.32.0/1950.13.32.1 to 50.13.63.25450.13.63.2558,190
10750.13.64.0/1950.13.64.1 to 50.13.95.25450.13.95.2558,190
10850.13.96.0/1950.13.96.1 to 50.13.127.25450.13.127.2558,190
10950.13.128.0/1950.13.128.1 to 50.13.159.25450.13.159.2558,190
11050.13.160.0/1950.13.160.1 to 50.13.191.25450.13.191.2558,190
11150.13.192.0/1950.13.192.1 to 50.13.223.25450.13.223.2558,190
11250.13.224.0/1950.13.224.1 to 50.13.255.25450.13.255.2558,190
11350.14.0.0/1950.14.0.1 to 50.14.31.25450.14.31.2558,190
11450.14.32.0/1950.14.32.1 to 50.14.63.25450.14.63.2558,190
11550.14.64.0/1950.14.64.1 to 50.14.95.25450.14.95.2558,190
11650.14.96.0/1950.14.96.1 to 50.14.127.25450.14.127.2558,190
11750.14.128.0/1950.14.128.1 to 50.14.159.25450.14.159.2558,190
11850.14.160.0/1950.14.160.1 to 50.14.191.25450.14.191.2558,190
11950.14.192.0/1950.14.192.1 to 50.14.223.25450.14.223.2558,190
12050.14.224.0/1950.14.224.1 to 50.14.255.25450.14.255.2558,190
12150.15.0.0/1950.15.0.1 to 50.15.31.25450.15.31.2558,190
12250.15.32.0/1950.15.32.1 to 50.15.63.25450.15.63.2558,190
12350.15.64.0/1950.15.64.1 to 50.15.95.25450.15.95.2558,190
12450.15.96.0/1950.15.96.1 to 50.15.127.25450.15.127.2558,190
12550.15.128.0/1950.15.128.1 to 50.15.159.25450.15.159.2558,190
12650.15.160.0/1950.15.160.1 to 50.15.191.25450.15.191.2558,190
12750.15.192.0/1950.15.192.1 to 50.15.223.25450.15.223.2558,190
12850.15.224.0/1950.15.224.1 to 50.15.255.25450.15.255.2558,190
12950.16.0.0/1950.16.0.1 to 50.16.31.25450.16.31.2558,190
13050.16.32.0/1950.16.32.1 to 50.16.63.25450.16.63.2558,190
13150.16.64.0/1950.16.64.1 to 50.16.95.25450.16.95.2558,190
13250.16.96.0/1950.16.96.1 to 50.16.127.25450.16.127.2558,190
13350.16.128.0/1950.16.128.1 to 50.16.159.25450.16.159.2558,190
13450.16.160.0/1950.16.160.1 to 50.16.191.25450.16.191.2558,190
13550.16.192.0/1950.16.192.1 to 50.16.223.25450.16.223.2558,190
13650.16.224.0/1950.16.224.1 to 50.16.255.25450.16.255.2558,190
13750.17.0.0/1950.17.0.1 to 50.17.31.25450.17.31.2558,190
13850.17.32.0/1950.17.32.1 to 50.17.63.25450.17.63.2558,190
13950.17.64.0/1950.17.64.1 to 50.17.95.25450.17.95.2558,190
14050.17.96.0/1950.17.96.1 to 50.17.127.25450.17.127.2558,190
14150.17.128.0/1950.17.128.1 to 50.17.159.25450.17.159.2558,190
14250.17.160.0/1950.17.160.1 to 50.17.191.25450.17.191.2558,190
14350.17.192.0/1950.17.192.1 to 50.17.223.25450.17.223.2558,190
14450.17.224.0/1950.17.224.1 to 50.17.255.25450.17.255.2558,190
14550.18.0.0/1950.18.0.1 to 50.18.31.25450.18.31.2558,190
14650.18.32.0/1950.18.32.1 to 50.18.63.25450.18.63.2558,190
14750.18.64.0/1950.18.64.1 to 50.18.95.25450.18.95.2558,190
14850.18.96.0/1950.18.96.1 to 50.18.127.25450.18.127.2558,190
14950.18.128.0/1950.18.128.1 to 50.18.159.25450.18.159.2558,190
15050.18.160.0/1950.18.160.1 to 50.18.191.25450.18.191.2558,190
15150.18.192.0/1950.18.192.1 to 50.18.223.25450.18.223.2558,190
15250.18.224.0/1950.18.224.1 to 50.18.255.25450.18.255.2558,190
15350.19.0.0/1950.19.0.1 to 50.19.31.25450.19.31.2558,190
15450.19.32.0/1950.19.32.1 to 50.19.63.25450.19.63.2558,190
15550.19.64.0/1950.19.64.1 to 50.19.95.25450.19.95.2558,190
15650.19.96.0/1950.19.96.1 to 50.19.127.25450.19.127.2558,190
15750.19.128.0/1950.19.128.1 to 50.19.159.25450.19.159.2558,190
15850.19.160.0/1950.19.160.1 to 50.19.191.25450.19.191.2558,190
15950.19.192.0/1950.19.192.1 to 50.19.223.25450.19.223.2558,190
16050.19.224.0/1950.19.224.1 to 50.19.255.25450.19.255.2558,190
16150.20.0.0/1950.20.0.1 to 50.20.31.25450.20.31.2558,190
16250.20.32.0/1950.20.32.1 to 50.20.63.25450.20.63.2558,190
16350.20.64.0/1950.20.64.1 to 50.20.95.25450.20.95.2558,190
16450.20.96.0/1950.20.96.1 to 50.20.127.25450.20.127.2558,190
16550.20.128.0/1950.20.128.1 to 50.20.159.25450.20.159.2558,190
16650.20.160.0/1950.20.160.1 to 50.20.191.25450.20.191.2558,190
16750.20.192.0/1950.20.192.1 to 50.20.223.25450.20.223.2558,190
16850.20.224.0/1950.20.224.1 to 50.20.255.25450.20.255.2558,190
16950.21.0.0/1950.21.0.1 to 50.21.31.25450.21.31.2558,190
17050.21.32.0/1950.21.32.1 to 50.21.63.25450.21.63.2558,190
17150.21.64.0/1950.21.64.1 to 50.21.95.25450.21.95.2558,190
17250.21.96.0/1950.21.96.1 to 50.21.127.25450.21.127.2558,190
17350.21.128.0/1950.21.128.1 to 50.21.159.25450.21.159.2558,190
17450.21.160.0/1950.21.160.1 to 50.21.191.25450.21.191.2558,190
17550.21.192.0/1950.21.192.1 to 50.21.223.25450.21.223.2558,190
17650.21.224.0/1950.21.224.1 to 50.21.255.25450.21.255.2558,190
17750.22.0.0/1950.22.0.1 to 50.22.31.25450.22.31.2558,190
17850.22.32.0/1950.22.32.1 to 50.22.63.25450.22.63.2558,190
17950.22.64.0/1950.22.64.1 to 50.22.95.25450.22.95.2558,190
18050.22.96.0/1950.22.96.1 to 50.22.127.25450.22.127.2558,190
18150.22.128.0/1950.22.128.1 to 50.22.159.25450.22.159.2558,190
18250.22.160.0/1950.22.160.1 to 50.22.191.25450.22.191.2558,190
18350.22.192.0/1950.22.192.1 to 50.22.223.25450.22.223.2558,190
18450.22.224.0/1950.22.224.1 to 50.22.255.25450.22.255.2558,190
18550.23.0.0/1950.23.0.1 to 50.23.31.25450.23.31.2558,190
18650.23.32.0/1950.23.32.1 to 50.23.63.25450.23.63.2558,190
18750.23.64.0/1950.23.64.1 to 50.23.95.25450.23.95.2558,190
18850.23.96.0/1950.23.96.1 to 50.23.127.25450.23.127.2558,190
18950.23.128.0/1950.23.128.1 to 50.23.159.25450.23.159.2558,190
19050.23.160.0/1950.23.160.1 to 50.23.191.25450.23.191.2558,190
19150.23.192.0/1950.23.192.1 to 50.23.223.25450.23.223.2558,190
19250.23.224.0/1950.23.224.1 to 50.23.255.25450.23.255.2558,190
19350.24.0.0/1950.24.0.1 to 50.24.31.25450.24.31.2558,190
19450.24.32.0/1950.24.32.1 to 50.24.63.25450.24.63.2558,190
19550.24.64.0/1950.24.64.1 to 50.24.95.25450.24.95.2558,190
19650.24.96.0/1950.24.96.1 to 50.24.127.25450.24.127.2558,190
19750.24.128.0/1950.24.128.1 to 50.24.159.25450.24.159.2558,190
19850.24.160.0/1950.24.160.1 to 50.24.191.25450.24.191.2558,190
19950.24.192.0/1950.24.192.1 to 50.24.223.25450.24.223.2558,190
20050.24.224.0/1950.24.224.1 to 50.24.255.25450.24.255.2558,190
20150.25.0.0/1950.25.0.1 to 50.25.31.25450.25.31.2558,190
20250.25.32.0/1950.25.32.1 to 50.25.63.25450.25.63.2558,190
20350.25.64.0/1950.25.64.1 to 50.25.95.25450.25.95.2558,190
20450.25.96.0/1950.25.96.1 to 50.25.127.25450.25.127.2558,190
20550.25.128.0/1950.25.128.1 to 50.25.159.25450.25.159.2558,190
20650.25.160.0/1950.25.160.1 to 50.25.191.25450.25.191.2558,190
20750.25.192.0/1950.25.192.1 to 50.25.223.25450.25.223.2558,190
20850.25.224.0/1950.25.224.1 to 50.25.255.25450.25.255.2558,190
20950.26.0.0/1950.26.0.1 to 50.26.31.25450.26.31.2558,190
21050.26.32.0/1950.26.32.1 to 50.26.63.25450.26.63.2558,190
21150.26.64.0/1950.26.64.1 to 50.26.95.25450.26.95.2558,190
21250.26.96.0/1950.26.96.1 to 50.26.127.25450.26.127.2558,190
21350.26.128.0/1950.26.128.1 to 50.26.159.25450.26.159.2558,190
21450.26.160.0/1950.26.160.1 to 50.26.191.25450.26.191.2558,190
21550.26.192.0/1950.26.192.1 to 50.26.223.25450.26.223.2558,190
21650.26.224.0/1950.26.224.1 to 50.26.255.25450.26.255.2558,190
21750.27.0.0/1950.27.0.1 to 50.27.31.25450.27.31.2558,190
21850.27.32.0/1950.27.32.1 to 50.27.63.25450.27.63.2558,190
21950.27.64.0/1950.27.64.1 to 50.27.95.25450.27.95.2558,190
22050.27.96.0/1950.27.96.1 to 50.27.127.25450.27.127.2558,190
22150.27.128.0/1950.27.128.1 to 50.27.159.25450.27.159.2558,190
22250.27.160.0/1950.27.160.1 to 50.27.191.25450.27.191.2558,190
22350.27.192.0/1950.27.192.1 to 50.27.223.25450.27.223.2558,190
22450.27.224.0/1950.27.224.1 to 50.27.255.25450.27.255.2558,190
22550.28.0.0/1950.28.0.1 to 50.28.31.25450.28.31.2558,190
22650.28.32.0/1950.28.32.1 to 50.28.63.25450.28.63.2558,190
22750.28.64.0/1950.28.64.1 to 50.28.95.25450.28.95.2558,190
22850.28.96.0/1950.28.96.1 to 50.28.127.25450.28.127.2558,190
22950.28.128.0/1950.28.128.1 to 50.28.159.25450.28.159.2558,190
23050.28.160.0/1950.28.160.1 to 50.28.191.25450.28.191.2558,190
23150.28.192.0/1950.28.192.1 to 50.28.223.25450.28.223.2558,190
23250.28.224.0/1950.28.224.1 to 50.28.255.25450.28.255.2558,190
23350.29.0.0/1950.29.0.1 to 50.29.31.25450.29.31.2558,190
23450.29.32.0/1950.29.32.1 to 50.29.63.25450.29.63.2558,190
23550.29.64.0/1950.29.64.1 to 50.29.95.25450.29.95.2558,190
23650.29.96.0/1950.29.96.1 to 50.29.127.25450.29.127.2558,190
23750.29.128.0/1950.29.128.1 to 50.29.159.25450.29.159.2558,190
23850.29.160.0/1950.29.160.1 to 50.29.191.25450.29.191.2558,190
23950.29.192.0/1950.29.192.1 to 50.29.223.25450.29.223.2558,190
24050.29.224.0/1950.29.224.1 to 50.29.255.25450.29.255.2558,190
24150.30.0.0/1950.30.0.1 to 50.30.31.25450.30.31.2558,190
24250.30.32.0/1950.30.32.1 to 50.30.63.25450.30.63.2558,190
24350.30.64.0/1950.30.64.1 to 50.30.95.25450.30.95.2558,190
24450.30.96.0/1950.30.96.1 to 50.30.127.25450.30.127.2558,190
24550.30.128.0/1950.30.128.1 to 50.30.159.25450.30.159.2558,190
24650.30.160.0/1950.30.160.1 to 50.30.191.25450.30.191.2558,190
24750.30.192.0/1950.30.192.1 to 50.30.223.25450.30.223.2558,190
24850.30.224.0/1950.30.224.1 to 50.30.255.25450.30.255.2558,190
24950.31.0.0/1950.31.0.1 to 50.31.31.25450.31.31.2558,190
25050.31.32.0/1950.31.32.1 to 50.31.63.25450.31.63.2558,190
25150.31.64.0/1950.31.64.1 to 50.31.95.25450.31.95.2558,190
25250.31.96.0/1950.31.96.1 to 50.31.127.25450.31.127.2558,190
25350.31.128.0/1950.31.128.1 to 50.31.159.25450.31.159.2558,190
25450.31.160.0/1950.31.160.1 to 50.31.191.25450.31.191.2558,190
25550.31.192.0/1950.31.192.1 to 50.31.223.25450.31.223.2558,190
25650.31.224.0/1950.31.224.1 to 50.31.255.25450.31.255.2558,190

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.