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.

Network97.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
97.0.0.0
Broadcast address
97.255.255.255
First usable
97.0.0.1
Last usable
97.255.255.254
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 61000000 · Integer 1627389952 to 1644167167
Reverse DNS zone
97.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100001..00000000.00000000.0000000097.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01100001..00000000.00000000.0000000097.0.0.0
Broadcast01100001..11111111.11111111.1111111197.255.255.255
Split into smaller subnets/18
/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)

97.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
197.0.0.0/1897.0.0.1 to 97.0.63.25497.0.63.25516,382
297.0.64.0/1897.0.64.1 to 97.0.127.25497.0.127.25516,382
397.0.128.0/1897.0.128.1 to 97.0.191.25497.0.191.25516,382
497.0.192.0/1897.0.192.1 to 97.0.255.25497.0.255.25516,382
597.1.0.0/1897.1.0.1 to 97.1.63.25497.1.63.25516,382
697.1.64.0/1897.1.64.1 to 97.1.127.25497.1.127.25516,382
797.1.128.0/1897.1.128.1 to 97.1.191.25497.1.191.25516,382
897.1.192.0/1897.1.192.1 to 97.1.255.25497.1.255.25516,382
997.2.0.0/1897.2.0.1 to 97.2.63.25497.2.63.25516,382
1097.2.64.0/1897.2.64.1 to 97.2.127.25497.2.127.25516,382
1197.2.128.0/1897.2.128.1 to 97.2.191.25497.2.191.25516,382
1297.2.192.0/1897.2.192.1 to 97.2.255.25497.2.255.25516,382
1397.3.0.0/1897.3.0.1 to 97.3.63.25497.3.63.25516,382
1497.3.64.0/1897.3.64.1 to 97.3.127.25497.3.127.25516,382
1597.3.128.0/1897.3.128.1 to 97.3.191.25497.3.191.25516,382
1697.3.192.0/1897.3.192.1 to 97.3.255.25497.3.255.25516,382
1797.4.0.0/1897.4.0.1 to 97.4.63.25497.4.63.25516,382
1897.4.64.0/1897.4.64.1 to 97.4.127.25497.4.127.25516,382
1997.4.128.0/1897.4.128.1 to 97.4.191.25497.4.191.25516,382
2097.4.192.0/1897.4.192.1 to 97.4.255.25497.4.255.25516,382
2197.5.0.0/1897.5.0.1 to 97.5.63.25497.5.63.25516,382
2297.5.64.0/1897.5.64.1 to 97.5.127.25497.5.127.25516,382
2397.5.128.0/1897.5.128.1 to 97.5.191.25497.5.191.25516,382
2497.5.192.0/1897.5.192.1 to 97.5.255.25497.5.255.25516,382
2597.6.0.0/1897.6.0.1 to 97.6.63.25497.6.63.25516,382
2697.6.64.0/1897.6.64.1 to 97.6.127.25497.6.127.25516,382
2797.6.128.0/1897.6.128.1 to 97.6.191.25497.6.191.25516,382
2897.6.192.0/1897.6.192.1 to 97.6.255.25497.6.255.25516,382
2997.7.0.0/1897.7.0.1 to 97.7.63.25497.7.63.25516,382
3097.7.64.0/1897.7.64.1 to 97.7.127.25497.7.127.25516,382
3197.7.128.0/1897.7.128.1 to 97.7.191.25497.7.191.25516,382
3297.7.192.0/1897.7.192.1 to 97.7.255.25497.7.255.25516,382
3397.8.0.0/1897.8.0.1 to 97.8.63.25497.8.63.25516,382
3497.8.64.0/1897.8.64.1 to 97.8.127.25497.8.127.25516,382
3597.8.128.0/1897.8.128.1 to 97.8.191.25497.8.191.25516,382
3697.8.192.0/1897.8.192.1 to 97.8.255.25497.8.255.25516,382
3797.9.0.0/1897.9.0.1 to 97.9.63.25497.9.63.25516,382
3897.9.64.0/1897.9.64.1 to 97.9.127.25497.9.127.25516,382
3997.9.128.0/1897.9.128.1 to 97.9.191.25497.9.191.25516,382
4097.9.192.0/1897.9.192.1 to 97.9.255.25497.9.255.25516,382
4197.10.0.0/1897.10.0.1 to 97.10.63.25497.10.63.25516,382
4297.10.64.0/1897.10.64.1 to 97.10.127.25497.10.127.25516,382
4397.10.128.0/1897.10.128.1 to 97.10.191.25497.10.191.25516,382
4497.10.192.0/1897.10.192.1 to 97.10.255.25497.10.255.25516,382
4597.11.0.0/1897.11.0.1 to 97.11.63.25497.11.63.25516,382
4697.11.64.0/1897.11.64.1 to 97.11.127.25497.11.127.25516,382
4797.11.128.0/1897.11.128.1 to 97.11.191.25497.11.191.25516,382
4897.11.192.0/1897.11.192.1 to 97.11.255.25497.11.255.25516,382
4997.12.0.0/1897.12.0.1 to 97.12.63.25497.12.63.25516,382
5097.12.64.0/1897.12.64.1 to 97.12.127.25497.12.127.25516,382
5197.12.128.0/1897.12.128.1 to 97.12.191.25497.12.191.25516,382
5297.12.192.0/1897.12.192.1 to 97.12.255.25497.12.255.25516,382
5397.13.0.0/1897.13.0.1 to 97.13.63.25497.13.63.25516,382
5497.13.64.0/1897.13.64.1 to 97.13.127.25497.13.127.25516,382
5597.13.128.0/1897.13.128.1 to 97.13.191.25497.13.191.25516,382
5697.13.192.0/1897.13.192.1 to 97.13.255.25497.13.255.25516,382
5797.14.0.0/1897.14.0.1 to 97.14.63.25497.14.63.25516,382
5897.14.64.0/1897.14.64.1 to 97.14.127.25497.14.127.25516,382
5997.14.128.0/1897.14.128.1 to 97.14.191.25497.14.191.25516,382
6097.14.192.0/1897.14.192.1 to 97.14.255.25497.14.255.25516,382
6197.15.0.0/1897.15.0.1 to 97.15.63.25497.15.63.25516,382
6297.15.64.0/1897.15.64.1 to 97.15.127.25497.15.127.25516,382
6397.15.128.0/1897.15.128.1 to 97.15.191.25497.15.191.25516,382
6497.15.192.0/1897.15.192.1 to 97.15.255.25497.15.255.25516,382
6597.16.0.0/1897.16.0.1 to 97.16.63.25497.16.63.25516,382
6697.16.64.0/1897.16.64.1 to 97.16.127.25497.16.127.25516,382
6797.16.128.0/1897.16.128.1 to 97.16.191.25497.16.191.25516,382
6897.16.192.0/1897.16.192.1 to 97.16.255.25497.16.255.25516,382
6997.17.0.0/1897.17.0.1 to 97.17.63.25497.17.63.25516,382
7097.17.64.0/1897.17.64.1 to 97.17.127.25497.17.127.25516,382
7197.17.128.0/1897.17.128.1 to 97.17.191.25497.17.191.25516,382
7297.17.192.0/1897.17.192.1 to 97.17.255.25497.17.255.25516,382
7397.18.0.0/1897.18.0.1 to 97.18.63.25497.18.63.25516,382
7497.18.64.0/1897.18.64.1 to 97.18.127.25497.18.127.25516,382
7597.18.128.0/1897.18.128.1 to 97.18.191.25497.18.191.25516,382
7697.18.192.0/1897.18.192.1 to 97.18.255.25497.18.255.25516,382
7797.19.0.0/1897.19.0.1 to 97.19.63.25497.19.63.25516,382
7897.19.64.0/1897.19.64.1 to 97.19.127.25497.19.127.25516,382
7997.19.128.0/1897.19.128.1 to 97.19.191.25497.19.191.25516,382
8097.19.192.0/1897.19.192.1 to 97.19.255.25497.19.255.25516,382
8197.20.0.0/1897.20.0.1 to 97.20.63.25497.20.63.25516,382
8297.20.64.0/1897.20.64.1 to 97.20.127.25497.20.127.25516,382
8397.20.128.0/1897.20.128.1 to 97.20.191.25497.20.191.25516,382
8497.20.192.0/1897.20.192.1 to 97.20.255.25497.20.255.25516,382
8597.21.0.0/1897.21.0.1 to 97.21.63.25497.21.63.25516,382
8697.21.64.0/1897.21.64.1 to 97.21.127.25497.21.127.25516,382
8797.21.128.0/1897.21.128.1 to 97.21.191.25497.21.191.25516,382
8897.21.192.0/1897.21.192.1 to 97.21.255.25497.21.255.25516,382
8997.22.0.0/1897.22.0.1 to 97.22.63.25497.22.63.25516,382
9097.22.64.0/1897.22.64.1 to 97.22.127.25497.22.127.25516,382
9197.22.128.0/1897.22.128.1 to 97.22.191.25497.22.191.25516,382
9297.22.192.0/1897.22.192.1 to 97.22.255.25497.22.255.25516,382
9397.23.0.0/1897.23.0.1 to 97.23.63.25497.23.63.25516,382
9497.23.64.0/1897.23.64.1 to 97.23.127.25497.23.127.25516,382
9597.23.128.0/1897.23.128.1 to 97.23.191.25497.23.191.25516,382
9697.23.192.0/1897.23.192.1 to 97.23.255.25497.23.255.25516,382
9797.24.0.0/1897.24.0.1 to 97.24.63.25497.24.63.25516,382
9897.24.64.0/1897.24.64.1 to 97.24.127.25497.24.127.25516,382
9997.24.128.0/1897.24.128.1 to 97.24.191.25497.24.191.25516,382
10097.24.192.0/1897.24.192.1 to 97.24.255.25497.24.255.25516,382
10197.25.0.0/1897.25.0.1 to 97.25.63.25497.25.63.25516,382
10297.25.64.0/1897.25.64.1 to 97.25.127.25497.25.127.25516,382
10397.25.128.0/1897.25.128.1 to 97.25.191.25497.25.191.25516,382
10497.25.192.0/1897.25.192.1 to 97.25.255.25497.25.255.25516,382
10597.26.0.0/1897.26.0.1 to 97.26.63.25497.26.63.25516,382
10697.26.64.0/1897.26.64.1 to 97.26.127.25497.26.127.25516,382
10797.26.128.0/1897.26.128.1 to 97.26.191.25497.26.191.25516,382
10897.26.192.0/1897.26.192.1 to 97.26.255.25497.26.255.25516,382
10997.27.0.0/1897.27.0.1 to 97.27.63.25497.27.63.25516,382
11097.27.64.0/1897.27.64.1 to 97.27.127.25497.27.127.25516,382
11197.27.128.0/1897.27.128.1 to 97.27.191.25497.27.191.25516,382
11297.27.192.0/1897.27.192.1 to 97.27.255.25497.27.255.25516,382
11397.28.0.0/1897.28.0.1 to 97.28.63.25497.28.63.25516,382
11497.28.64.0/1897.28.64.1 to 97.28.127.25497.28.127.25516,382
11597.28.128.0/1897.28.128.1 to 97.28.191.25497.28.191.25516,382
11697.28.192.0/1897.28.192.1 to 97.28.255.25497.28.255.25516,382
11797.29.0.0/1897.29.0.1 to 97.29.63.25497.29.63.25516,382
11897.29.64.0/1897.29.64.1 to 97.29.127.25497.29.127.25516,382
11997.29.128.0/1897.29.128.1 to 97.29.191.25497.29.191.25516,382
12097.29.192.0/1897.29.192.1 to 97.29.255.25497.29.255.25516,382
12197.30.0.0/1897.30.0.1 to 97.30.63.25497.30.63.25516,382
12297.30.64.0/1897.30.64.1 to 97.30.127.25497.30.127.25516,382
12397.30.128.0/1897.30.128.1 to 97.30.191.25497.30.191.25516,382
12497.30.192.0/1897.30.192.1 to 97.30.255.25497.30.255.25516,382
12597.31.0.0/1897.31.0.1 to 97.31.63.25497.31.63.25516,382
12697.31.64.0/1897.31.64.1 to 97.31.127.25497.31.127.25516,382
12797.31.128.0/1897.31.128.1 to 97.31.191.25497.31.191.25516,382
12897.31.192.0/1897.31.192.1 to 97.31.255.25497.31.255.25516,382
12997.32.0.0/1897.32.0.1 to 97.32.63.25497.32.63.25516,382
13097.32.64.0/1897.32.64.1 to 97.32.127.25497.32.127.25516,382
13197.32.128.0/1897.32.128.1 to 97.32.191.25497.32.191.25516,382
13297.32.192.0/1897.32.192.1 to 97.32.255.25497.32.255.25516,382
13397.33.0.0/1897.33.0.1 to 97.33.63.25497.33.63.25516,382
13497.33.64.0/1897.33.64.1 to 97.33.127.25497.33.127.25516,382
13597.33.128.0/1897.33.128.1 to 97.33.191.25497.33.191.25516,382
13697.33.192.0/1897.33.192.1 to 97.33.255.25497.33.255.25516,382
13797.34.0.0/1897.34.0.1 to 97.34.63.25497.34.63.25516,382
13897.34.64.0/1897.34.64.1 to 97.34.127.25497.34.127.25516,382
13997.34.128.0/1897.34.128.1 to 97.34.191.25497.34.191.25516,382
14097.34.192.0/1897.34.192.1 to 97.34.255.25497.34.255.25516,382
14197.35.0.0/1897.35.0.1 to 97.35.63.25497.35.63.25516,382
14297.35.64.0/1897.35.64.1 to 97.35.127.25497.35.127.25516,382
14397.35.128.0/1897.35.128.1 to 97.35.191.25497.35.191.25516,382
14497.35.192.0/1897.35.192.1 to 97.35.255.25497.35.255.25516,382
14597.36.0.0/1897.36.0.1 to 97.36.63.25497.36.63.25516,382
14697.36.64.0/1897.36.64.1 to 97.36.127.25497.36.127.25516,382
14797.36.128.0/1897.36.128.1 to 97.36.191.25497.36.191.25516,382
14897.36.192.0/1897.36.192.1 to 97.36.255.25497.36.255.25516,382
14997.37.0.0/1897.37.0.1 to 97.37.63.25497.37.63.25516,382
15097.37.64.0/1897.37.64.1 to 97.37.127.25497.37.127.25516,382
15197.37.128.0/1897.37.128.1 to 97.37.191.25497.37.191.25516,382
15297.37.192.0/1897.37.192.1 to 97.37.255.25497.37.255.25516,382
15397.38.0.0/1897.38.0.1 to 97.38.63.25497.38.63.25516,382
15497.38.64.0/1897.38.64.1 to 97.38.127.25497.38.127.25516,382
15597.38.128.0/1897.38.128.1 to 97.38.191.25497.38.191.25516,382
15697.38.192.0/1897.38.192.1 to 97.38.255.25497.38.255.25516,382
15797.39.0.0/1897.39.0.1 to 97.39.63.25497.39.63.25516,382
15897.39.64.0/1897.39.64.1 to 97.39.127.25497.39.127.25516,382
15997.39.128.0/1897.39.128.1 to 97.39.191.25497.39.191.25516,382
16097.39.192.0/1897.39.192.1 to 97.39.255.25497.39.255.25516,382
16197.40.0.0/1897.40.0.1 to 97.40.63.25497.40.63.25516,382
16297.40.64.0/1897.40.64.1 to 97.40.127.25497.40.127.25516,382
16397.40.128.0/1897.40.128.1 to 97.40.191.25497.40.191.25516,382
16497.40.192.0/1897.40.192.1 to 97.40.255.25497.40.255.25516,382
16597.41.0.0/1897.41.0.1 to 97.41.63.25497.41.63.25516,382
16697.41.64.0/1897.41.64.1 to 97.41.127.25497.41.127.25516,382
16797.41.128.0/1897.41.128.1 to 97.41.191.25497.41.191.25516,382
16897.41.192.0/1897.41.192.1 to 97.41.255.25497.41.255.25516,382
16997.42.0.0/1897.42.0.1 to 97.42.63.25497.42.63.25516,382
17097.42.64.0/1897.42.64.1 to 97.42.127.25497.42.127.25516,382
17197.42.128.0/1897.42.128.1 to 97.42.191.25497.42.191.25516,382
17297.42.192.0/1897.42.192.1 to 97.42.255.25497.42.255.25516,382
17397.43.0.0/1897.43.0.1 to 97.43.63.25497.43.63.25516,382
17497.43.64.0/1897.43.64.1 to 97.43.127.25497.43.127.25516,382
17597.43.128.0/1897.43.128.1 to 97.43.191.25497.43.191.25516,382
17697.43.192.0/1897.43.192.1 to 97.43.255.25497.43.255.25516,382
17797.44.0.0/1897.44.0.1 to 97.44.63.25497.44.63.25516,382
17897.44.64.0/1897.44.64.1 to 97.44.127.25497.44.127.25516,382
17997.44.128.0/1897.44.128.1 to 97.44.191.25497.44.191.25516,382
18097.44.192.0/1897.44.192.1 to 97.44.255.25497.44.255.25516,382
18197.45.0.0/1897.45.0.1 to 97.45.63.25497.45.63.25516,382
18297.45.64.0/1897.45.64.1 to 97.45.127.25497.45.127.25516,382
18397.45.128.0/1897.45.128.1 to 97.45.191.25497.45.191.25516,382
18497.45.192.0/1897.45.192.1 to 97.45.255.25497.45.255.25516,382
18597.46.0.0/1897.46.0.1 to 97.46.63.25497.46.63.25516,382
18697.46.64.0/1897.46.64.1 to 97.46.127.25497.46.127.25516,382
18797.46.128.0/1897.46.128.1 to 97.46.191.25497.46.191.25516,382
18897.46.192.0/1897.46.192.1 to 97.46.255.25497.46.255.25516,382
18997.47.0.0/1897.47.0.1 to 97.47.63.25497.47.63.25516,382
19097.47.64.0/1897.47.64.1 to 97.47.127.25497.47.127.25516,382
19197.47.128.0/1897.47.128.1 to 97.47.191.25497.47.191.25516,382
19297.47.192.0/1897.47.192.1 to 97.47.255.25497.47.255.25516,382
19397.48.0.0/1897.48.0.1 to 97.48.63.25497.48.63.25516,382
19497.48.64.0/1897.48.64.1 to 97.48.127.25497.48.127.25516,382
19597.48.128.0/1897.48.128.1 to 97.48.191.25497.48.191.25516,382
19697.48.192.0/1897.48.192.1 to 97.48.255.25497.48.255.25516,382
19797.49.0.0/1897.49.0.1 to 97.49.63.25497.49.63.25516,382
19897.49.64.0/1897.49.64.1 to 97.49.127.25497.49.127.25516,382
19997.49.128.0/1897.49.128.1 to 97.49.191.25497.49.191.25516,382
20097.49.192.0/1897.49.192.1 to 97.49.255.25497.49.255.25516,382
20197.50.0.0/1897.50.0.1 to 97.50.63.25497.50.63.25516,382
20297.50.64.0/1897.50.64.1 to 97.50.127.25497.50.127.25516,382
20397.50.128.0/1897.50.128.1 to 97.50.191.25497.50.191.25516,382
20497.50.192.0/1897.50.192.1 to 97.50.255.25497.50.255.25516,382
20597.51.0.0/1897.51.0.1 to 97.51.63.25497.51.63.25516,382
20697.51.64.0/1897.51.64.1 to 97.51.127.25497.51.127.25516,382
20797.51.128.0/1897.51.128.1 to 97.51.191.25497.51.191.25516,382
20897.51.192.0/1897.51.192.1 to 97.51.255.25497.51.255.25516,382
20997.52.0.0/1897.52.0.1 to 97.52.63.25497.52.63.25516,382
21097.52.64.0/1897.52.64.1 to 97.52.127.25497.52.127.25516,382
21197.52.128.0/1897.52.128.1 to 97.52.191.25497.52.191.25516,382
21297.52.192.0/1897.52.192.1 to 97.52.255.25497.52.255.25516,382
21397.53.0.0/1897.53.0.1 to 97.53.63.25497.53.63.25516,382
21497.53.64.0/1897.53.64.1 to 97.53.127.25497.53.127.25516,382
21597.53.128.0/1897.53.128.1 to 97.53.191.25497.53.191.25516,382
21697.53.192.0/1897.53.192.1 to 97.53.255.25497.53.255.25516,382
21797.54.0.0/1897.54.0.1 to 97.54.63.25497.54.63.25516,382
21897.54.64.0/1897.54.64.1 to 97.54.127.25497.54.127.25516,382
21997.54.128.0/1897.54.128.1 to 97.54.191.25497.54.191.25516,382
22097.54.192.0/1897.54.192.1 to 97.54.255.25497.54.255.25516,382
22197.55.0.0/1897.55.0.1 to 97.55.63.25497.55.63.25516,382
22297.55.64.0/1897.55.64.1 to 97.55.127.25497.55.127.25516,382
22397.55.128.0/1897.55.128.1 to 97.55.191.25497.55.191.25516,382
22497.55.192.0/1897.55.192.1 to 97.55.255.25497.55.255.25516,382
22597.56.0.0/1897.56.0.1 to 97.56.63.25497.56.63.25516,382
22697.56.64.0/1897.56.64.1 to 97.56.127.25497.56.127.25516,382
22797.56.128.0/1897.56.128.1 to 97.56.191.25497.56.191.25516,382
22897.56.192.0/1897.56.192.1 to 97.56.255.25497.56.255.25516,382
22997.57.0.0/1897.57.0.1 to 97.57.63.25497.57.63.25516,382
23097.57.64.0/1897.57.64.1 to 97.57.127.25497.57.127.25516,382
23197.57.128.0/1897.57.128.1 to 97.57.191.25497.57.191.25516,382
23297.57.192.0/1897.57.192.1 to 97.57.255.25497.57.255.25516,382
23397.58.0.0/1897.58.0.1 to 97.58.63.25497.58.63.25516,382
23497.58.64.0/1897.58.64.1 to 97.58.127.25497.58.127.25516,382
23597.58.128.0/1897.58.128.1 to 97.58.191.25497.58.191.25516,382
23697.58.192.0/1897.58.192.1 to 97.58.255.25497.58.255.25516,382
23797.59.0.0/1897.59.0.1 to 97.59.63.25497.59.63.25516,382
23897.59.64.0/1897.59.64.1 to 97.59.127.25497.59.127.25516,382
23997.59.128.0/1897.59.128.1 to 97.59.191.25497.59.191.25516,382
24097.59.192.0/1897.59.192.1 to 97.59.255.25497.59.255.25516,382
24197.60.0.0/1897.60.0.1 to 97.60.63.25497.60.63.25516,382
24297.60.64.0/1897.60.64.1 to 97.60.127.25497.60.127.25516,382
24397.60.128.0/1897.60.128.1 to 97.60.191.25497.60.191.25516,382
24497.60.192.0/1897.60.192.1 to 97.60.255.25497.60.255.25516,382
24597.61.0.0/1897.61.0.1 to 97.61.63.25497.61.63.25516,382
24697.61.64.0/1897.61.64.1 to 97.61.127.25497.61.127.25516,382
24797.61.128.0/1897.61.128.1 to 97.61.191.25497.61.191.25516,382
24897.61.192.0/1897.61.192.1 to 97.61.255.25497.61.255.25516,382
24997.62.0.0/1897.62.0.1 to 97.62.63.25497.62.63.25516,382
25097.62.64.0/1897.62.64.1 to 97.62.127.25497.62.127.25516,382
25197.62.128.0/1897.62.128.1 to 97.62.191.25497.62.191.25516,382
25297.62.192.0/1897.62.192.1 to 97.62.255.25497.62.255.25516,382
25397.63.0.0/1897.63.0.1 to 97.63.63.25497.63.63.25516,382
25497.63.64.0/1897.63.64.1 to 97.63.127.25497.63.127.25516,382
25597.63.128.0/1897.63.128.1 to 97.63.191.25497.63.191.25516,382
25697.63.192.0/1897.63.192.1 to 97.63.255.25497.63.255.25516,382

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.