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.

Network48.44.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
48.44.0.0
Broadcast address
48.45.255.255
First usable
48.44.0.1
Last usable
48.45.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 302C0000 · Integer 808189952 to 808321023
Reverse DNS zones
44.48.in-addr.arpa
45.48.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00110000.00101100.00000000.0000000048.44.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00110000.00101100.00000000.0000000048.44.0.0
Broadcast00110000.00101101.11111111.1111111148.45.255.255
Split into smaller subnets/27
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

48.44.0.0/15 makes 4,096 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
148.44.0.0/2748.44.0.1 to 48.44.0.3048.44.0.3130
248.44.0.32/2748.44.0.33 to 48.44.0.6248.44.0.6330
348.44.0.64/2748.44.0.65 to 48.44.0.9448.44.0.9530
448.44.0.96/2748.44.0.97 to 48.44.0.12648.44.0.12730
548.44.0.128/2748.44.0.129 to 48.44.0.15848.44.0.15930
648.44.0.160/2748.44.0.161 to 48.44.0.19048.44.0.19130
748.44.0.192/2748.44.0.193 to 48.44.0.22248.44.0.22330
848.44.0.224/2748.44.0.225 to 48.44.0.25448.44.0.25530
948.44.1.0/2748.44.1.1 to 48.44.1.3048.44.1.3130
1048.44.1.32/2748.44.1.33 to 48.44.1.6248.44.1.6330
1148.44.1.64/2748.44.1.65 to 48.44.1.9448.44.1.9530
1248.44.1.96/2748.44.1.97 to 48.44.1.12648.44.1.12730
1348.44.1.128/2748.44.1.129 to 48.44.1.15848.44.1.15930
1448.44.1.160/2748.44.1.161 to 48.44.1.19048.44.1.19130
1548.44.1.192/2748.44.1.193 to 48.44.1.22248.44.1.22330
1648.44.1.224/2748.44.1.225 to 48.44.1.25448.44.1.25530
1748.44.2.0/2748.44.2.1 to 48.44.2.3048.44.2.3130
1848.44.2.32/2748.44.2.33 to 48.44.2.6248.44.2.6330
1948.44.2.64/2748.44.2.65 to 48.44.2.9448.44.2.9530
2048.44.2.96/2748.44.2.97 to 48.44.2.12648.44.2.12730
2148.44.2.128/2748.44.2.129 to 48.44.2.15848.44.2.15930
2248.44.2.160/2748.44.2.161 to 48.44.2.19048.44.2.19130
2348.44.2.192/2748.44.2.193 to 48.44.2.22248.44.2.22330
2448.44.2.224/2748.44.2.225 to 48.44.2.25448.44.2.25530
2548.44.3.0/2748.44.3.1 to 48.44.3.3048.44.3.3130
2648.44.3.32/2748.44.3.33 to 48.44.3.6248.44.3.6330
2748.44.3.64/2748.44.3.65 to 48.44.3.9448.44.3.9530
2848.44.3.96/2748.44.3.97 to 48.44.3.12648.44.3.12730
2948.44.3.128/2748.44.3.129 to 48.44.3.15848.44.3.15930
3048.44.3.160/2748.44.3.161 to 48.44.3.19048.44.3.19130
3148.44.3.192/2748.44.3.193 to 48.44.3.22248.44.3.22330
3248.44.3.224/2748.44.3.225 to 48.44.3.25448.44.3.25530
3348.44.4.0/2748.44.4.1 to 48.44.4.3048.44.4.3130
3448.44.4.32/2748.44.4.33 to 48.44.4.6248.44.4.6330
3548.44.4.64/2748.44.4.65 to 48.44.4.9448.44.4.9530
3648.44.4.96/2748.44.4.97 to 48.44.4.12648.44.4.12730
3748.44.4.128/2748.44.4.129 to 48.44.4.15848.44.4.15930
3848.44.4.160/2748.44.4.161 to 48.44.4.19048.44.4.19130
3948.44.4.192/2748.44.4.193 to 48.44.4.22248.44.4.22330
4048.44.4.224/2748.44.4.225 to 48.44.4.25448.44.4.25530
4148.44.5.0/2748.44.5.1 to 48.44.5.3048.44.5.3130
4248.44.5.32/2748.44.5.33 to 48.44.5.6248.44.5.6330
4348.44.5.64/2748.44.5.65 to 48.44.5.9448.44.5.9530
4448.44.5.96/2748.44.5.97 to 48.44.5.12648.44.5.12730
4548.44.5.128/2748.44.5.129 to 48.44.5.15848.44.5.15930
4648.44.5.160/2748.44.5.161 to 48.44.5.19048.44.5.19130
4748.44.5.192/2748.44.5.193 to 48.44.5.22248.44.5.22330
4848.44.5.224/2748.44.5.225 to 48.44.5.25448.44.5.25530
4948.44.6.0/2748.44.6.1 to 48.44.6.3048.44.6.3130
5048.44.6.32/2748.44.6.33 to 48.44.6.6248.44.6.6330
5148.44.6.64/2748.44.6.65 to 48.44.6.9448.44.6.9530
5248.44.6.96/2748.44.6.97 to 48.44.6.12648.44.6.12730
5348.44.6.128/2748.44.6.129 to 48.44.6.15848.44.6.15930
5448.44.6.160/2748.44.6.161 to 48.44.6.19048.44.6.19130
5548.44.6.192/2748.44.6.193 to 48.44.6.22248.44.6.22330
5648.44.6.224/2748.44.6.225 to 48.44.6.25448.44.6.25530
5748.44.7.0/2748.44.7.1 to 48.44.7.3048.44.7.3130
5848.44.7.32/2748.44.7.33 to 48.44.7.6248.44.7.6330
5948.44.7.64/2748.44.7.65 to 48.44.7.9448.44.7.9530
6048.44.7.96/2748.44.7.97 to 48.44.7.12648.44.7.12730
6148.44.7.128/2748.44.7.129 to 48.44.7.15848.44.7.15930
6248.44.7.160/2748.44.7.161 to 48.44.7.19048.44.7.19130
6348.44.7.192/2748.44.7.193 to 48.44.7.22248.44.7.22330
6448.44.7.224/2748.44.7.225 to 48.44.7.25448.44.7.25530
6548.44.8.0/2748.44.8.1 to 48.44.8.3048.44.8.3130
6648.44.8.32/2748.44.8.33 to 48.44.8.6248.44.8.6330
6748.44.8.64/2748.44.8.65 to 48.44.8.9448.44.8.9530
6848.44.8.96/2748.44.8.97 to 48.44.8.12648.44.8.12730
6948.44.8.128/2748.44.8.129 to 48.44.8.15848.44.8.15930
7048.44.8.160/2748.44.8.161 to 48.44.8.19048.44.8.19130
7148.44.8.192/2748.44.8.193 to 48.44.8.22248.44.8.22330
7248.44.8.224/2748.44.8.225 to 48.44.8.25448.44.8.25530
7348.44.9.0/2748.44.9.1 to 48.44.9.3048.44.9.3130
7448.44.9.32/2748.44.9.33 to 48.44.9.6248.44.9.6330
7548.44.9.64/2748.44.9.65 to 48.44.9.9448.44.9.9530
7648.44.9.96/2748.44.9.97 to 48.44.9.12648.44.9.12730
7748.44.9.128/2748.44.9.129 to 48.44.9.15848.44.9.15930
7848.44.9.160/2748.44.9.161 to 48.44.9.19048.44.9.19130
7948.44.9.192/2748.44.9.193 to 48.44.9.22248.44.9.22330
8048.44.9.224/2748.44.9.225 to 48.44.9.25448.44.9.25530
8148.44.10.0/2748.44.10.1 to 48.44.10.3048.44.10.3130
8248.44.10.32/2748.44.10.33 to 48.44.10.6248.44.10.6330
8348.44.10.64/2748.44.10.65 to 48.44.10.9448.44.10.9530
8448.44.10.96/2748.44.10.97 to 48.44.10.12648.44.10.12730
8548.44.10.128/2748.44.10.129 to 48.44.10.15848.44.10.15930
8648.44.10.160/2748.44.10.161 to 48.44.10.19048.44.10.19130
8748.44.10.192/2748.44.10.193 to 48.44.10.22248.44.10.22330
8848.44.10.224/2748.44.10.225 to 48.44.10.25448.44.10.25530
8948.44.11.0/2748.44.11.1 to 48.44.11.3048.44.11.3130
9048.44.11.32/2748.44.11.33 to 48.44.11.6248.44.11.6330
9148.44.11.64/2748.44.11.65 to 48.44.11.9448.44.11.9530
9248.44.11.96/2748.44.11.97 to 48.44.11.12648.44.11.12730
9348.44.11.128/2748.44.11.129 to 48.44.11.15848.44.11.15930
9448.44.11.160/2748.44.11.161 to 48.44.11.19048.44.11.19130
9548.44.11.192/2748.44.11.193 to 48.44.11.22248.44.11.22330
9648.44.11.224/2748.44.11.225 to 48.44.11.25448.44.11.25530
9748.44.12.0/2748.44.12.1 to 48.44.12.3048.44.12.3130
9848.44.12.32/2748.44.12.33 to 48.44.12.6248.44.12.6330
9948.44.12.64/2748.44.12.65 to 48.44.12.9448.44.12.9530
10048.44.12.96/2748.44.12.97 to 48.44.12.12648.44.12.12730
10148.44.12.128/2748.44.12.129 to 48.44.12.15848.44.12.15930
10248.44.12.160/2748.44.12.161 to 48.44.12.19048.44.12.19130
10348.44.12.192/2748.44.12.193 to 48.44.12.22248.44.12.22330
10448.44.12.224/2748.44.12.225 to 48.44.12.25448.44.12.25530
10548.44.13.0/2748.44.13.1 to 48.44.13.3048.44.13.3130
10648.44.13.32/2748.44.13.33 to 48.44.13.6248.44.13.6330
10748.44.13.64/2748.44.13.65 to 48.44.13.9448.44.13.9530
10848.44.13.96/2748.44.13.97 to 48.44.13.12648.44.13.12730
10948.44.13.128/2748.44.13.129 to 48.44.13.15848.44.13.15930
11048.44.13.160/2748.44.13.161 to 48.44.13.19048.44.13.19130
11148.44.13.192/2748.44.13.193 to 48.44.13.22248.44.13.22330
11248.44.13.224/2748.44.13.225 to 48.44.13.25448.44.13.25530
11348.44.14.0/2748.44.14.1 to 48.44.14.3048.44.14.3130
11448.44.14.32/2748.44.14.33 to 48.44.14.6248.44.14.6330
11548.44.14.64/2748.44.14.65 to 48.44.14.9448.44.14.9530
11648.44.14.96/2748.44.14.97 to 48.44.14.12648.44.14.12730
11748.44.14.128/2748.44.14.129 to 48.44.14.15848.44.14.15930
11848.44.14.160/2748.44.14.161 to 48.44.14.19048.44.14.19130
11948.44.14.192/2748.44.14.193 to 48.44.14.22248.44.14.22330
12048.44.14.224/2748.44.14.225 to 48.44.14.25448.44.14.25530
12148.44.15.0/2748.44.15.1 to 48.44.15.3048.44.15.3130
12248.44.15.32/2748.44.15.33 to 48.44.15.6248.44.15.6330
12348.44.15.64/2748.44.15.65 to 48.44.15.9448.44.15.9530
12448.44.15.96/2748.44.15.97 to 48.44.15.12648.44.15.12730
12548.44.15.128/2748.44.15.129 to 48.44.15.15848.44.15.15930
12648.44.15.160/2748.44.15.161 to 48.44.15.19048.44.15.19130
12748.44.15.192/2748.44.15.193 to 48.44.15.22248.44.15.22330
12848.44.15.224/2748.44.15.225 to 48.44.15.25448.44.15.25530
12948.44.16.0/2748.44.16.1 to 48.44.16.3048.44.16.3130
13048.44.16.32/2748.44.16.33 to 48.44.16.6248.44.16.6330
13148.44.16.64/2748.44.16.65 to 48.44.16.9448.44.16.9530
13248.44.16.96/2748.44.16.97 to 48.44.16.12648.44.16.12730
13348.44.16.128/2748.44.16.129 to 48.44.16.15848.44.16.15930
13448.44.16.160/2748.44.16.161 to 48.44.16.19048.44.16.19130
13548.44.16.192/2748.44.16.193 to 48.44.16.22248.44.16.22330
13648.44.16.224/2748.44.16.225 to 48.44.16.25448.44.16.25530
13748.44.17.0/2748.44.17.1 to 48.44.17.3048.44.17.3130
13848.44.17.32/2748.44.17.33 to 48.44.17.6248.44.17.6330
13948.44.17.64/2748.44.17.65 to 48.44.17.9448.44.17.9530
14048.44.17.96/2748.44.17.97 to 48.44.17.12648.44.17.12730
14148.44.17.128/2748.44.17.129 to 48.44.17.15848.44.17.15930
14248.44.17.160/2748.44.17.161 to 48.44.17.19048.44.17.19130
14348.44.17.192/2748.44.17.193 to 48.44.17.22248.44.17.22330
14448.44.17.224/2748.44.17.225 to 48.44.17.25448.44.17.25530
14548.44.18.0/2748.44.18.1 to 48.44.18.3048.44.18.3130
14648.44.18.32/2748.44.18.33 to 48.44.18.6248.44.18.6330
14748.44.18.64/2748.44.18.65 to 48.44.18.9448.44.18.9530
14848.44.18.96/2748.44.18.97 to 48.44.18.12648.44.18.12730
14948.44.18.128/2748.44.18.129 to 48.44.18.15848.44.18.15930
15048.44.18.160/2748.44.18.161 to 48.44.18.19048.44.18.19130
15148.44.18.192/2748.44.18.193 to 48.44.18.22248.44.18.22330
15248.44.18.224/2748.44.18.225 to 48.44.18.25448.44.18.25530
15348.44.19.0/2748.44.19.1 to 48.44.19.3048.44.19.3130
15448.44.19.32/2748.44.19.33 to 48.44.19.6248.44.19.6330
15548.44.19.64/2748.44.19.65 to 48.44.19.9448.44.19.9530
15648.44.19.96/2748.44.19.97 to 48.44.19.12648.44.19.12730
15748.44.19.128/2748.44.19.129 to 48.44.19.15848.44.19.15930
15848.44.19.160/2748.44.19.161 to 48.44.19.19048.44.19.19130
15948.44.19.192/2748.44.19.193 to 48.44.19.22248.44.19.22330
16048.44.19.224/2748.44.19.225 to 48.44.19.25448.44.19.25530
16148.44.20.0/2748.44.20.1 to 48.44.20.3048.44.20.3130
16248.44.20.32/2748.44.20.33 to 48.44.20.6248.44.20.6330
16348.44.20.64/2748.44.20.65 to 48.44.20.9448.44.20.9530
16448.44.20.96/2748.44.20.97 to 48.44.20.12648.44.20.12730
16548.44.20.128/2748.44.20.129 to 48.44.20.15848.44.20.15930
16648.44.20.160/2748.44.20.161 to 48.44.20.19048.44.20.19130
16748.44.20.192/2748.44.20.193 to 48.44.20.22248.44.20.22330
16848.44.20.224/2748.44.20.225 to 48.44.20.25448.44.20.25530
16948.44.21.0/2748.44.21.1 to 48.44.21.3048.44.21.3130
17048.44.21.32/2748.44.21.33 to 48.44.21.6248.44.21.6330
17148.44.21.64/2748.44.21.65 to 48.44.21.9448.44.21.9530
17248.44.21.96/2748.44.21.97 to 48.44.21.12648.44.21.12730
17348.44.21.128/2748.44.21.129 to 48.44.21.15848.44.21.15930
17448.44.21.160/2748.44.21.161 to 48.44.21.19048.44.21.19130
17548.44.21.192/2748.44.21.193 to 48.44.21.22248.44.21.22330
17648.44.21.224/2748.44.21.225 to 48.44.21.25448.44.21.25530
17748.44.22.0/2748.44.22.1 to 48.44.22.3048.44.22.3130
17848.44.22.32/2748.44.22.33 to 48.44.22.6248.44.22.6330
17948.44.22.64/2748.44.22.65 to 48.44.22.9448.44.22.9530
18048.44.22.96/2748.44.22.97 to 48.44.22.12648.44.22.12730
18148.44.22.128/2748.44.22.129 to 48.44.22.15848.44.22.15930
18248.44.22.160/2748.44.22.161 to 48.44.22.19048.44.22.19130
18348.44.22.192/2748.44.22.193 to 48.44.22.22248.44.22.22330
18448.44.22.224/2748.44.22.225 to 48.44.22.25448.44.22.25530
18548.44.23.0/2748.44.23.1 to 48.44.23.3048.44.23.3130
18648.44.23.32/2748.44.23.33 to 48.44.23.6248.44.23.6330
18748.44.23.64/2748.44.23.65 to 48.44.23.9448.44.23.9530
18848.44.23.96/2748.44.23.97 to 48.44.23.12648.44.23.12730
18948.44.23.128/2748.44.23.129 to 48.44.23.15848.44.23.15930
19048.44.23.160/2748.44.23.161 to 48.44.23.19048.44.23.19130
19148.44.23.192/2748.44.23.193 to 48.44.23.22248.44.23.22330
19248.44.23.224/2748.44.23.225 to 48.44.23.25448.44.23.25530
19348.44.24.0/2748.44.24.1 to 48.44.24.3048.44.24.3130
19448.44.24.32/2748.44.24.33 to 48.44.24.6248.44.24.6330
19548.44.24.64/2748.44.24.65 to 48.44.24.9448.44.24.9530
19648.44.24.96/2748.44.24.97 to 48.44.24.12648.44.24.12730
19748.44.24.128/2748.44.24.129 to 48.44.24.15848.44.24.15930
19848.44.24.160/2748.44.24.161 to 48.44.24.19048.44.24.19130
19948.44.24.192/2748.44.24.193 to 48.44.24.22248.44.24.22330
20048.44.24.224/2748.44.24.225 to 48.44.24.25448.44.24.25530
20148.44.25.0/2748.44.25.1 to 48.44.25.3048.44.25.3130
20248.44.25.32/2748.44.25.33 to 48.44.25.6248.44.25.6330
20348.44.25.64/2748.44.25.65 to 48.44.25.9448.44.25.9530
20448.44.25.96/2748.44.25.97 to 48.44.25.12648.44.25.12730
20548.44.25.128/2748.44.25.129 to 48.44.25.15848.44.25.15930
20648.44.25.160/2748.44.25.161 to 48.44.25.19048.44.25.19130
20748.44.25.192/2748.44.25.193 to 48.44.25.22248.44.25.22330
20848.44.25.224/2748.44.25.225 to 48.44.25.25448.44.25.25530
20948.44.26.0/2748.44.26.1 to 48.44.26.3048.44.26.3130
21048.44.26.32/2748.44.26.33 to 48.44.26.6248.44.26.6330
21148.44.26.64/2748.44.26.65 to 48.44.26.9448.44.26.9530
21248.44.26.96/2748.44.26.97 to 48.44.26.12648.44.26.12730
21348.44.26.128/2748.44.26.129 to 48.44.26.15848.44.26.15930
21448.44.26.160/2748.44.26.161 to 48.44.26.19048.44.26.19130
21548.44.26.192/2748.44.26.193 to 48.44.26.22248.44.26.22330
21648.44.26.224/2748.44.26.225 to 48.44.26.25448.44.26.25530
21748.44.27.0/2748.44.27.1 to 48.44.27.3048.44.27.3130
21848.44.27.32/2748.44.27.33 to 48.44.27.6248.44.27.6330
21948.44.27.64/2748.44.27.65 to 48.44.27.9448.44.27.9530
22048.44.27.96/2748.44.27.97 to 48.44.27.12648.44.27.12730
22148.44.27.128/2748.44.27.129 to 48.44.27.15848.44.27.15930
22248.44.27.160/2748.44.27.161 to 48.44.27.19048.44.27.19130
22348.44.27.192/2748.44.27.193 to 48.44.27.22248.44.27.22330
22448.44.27.224/2748.44.27.225 to 48.44.27.25448.44.27.25530
22548.44.28.0/2748.44.28.1 to 48.44.28.3048.44.28.3130
22648.44.28.32/2748.44.28.33 to 48.44.28.6248.44.28.6330
22748.44.28.64/2748.44.28.65 to 48.44.28.9448.44.28.9530
22848.44.28.96/2748.44.28.97 to 48.44.28.12648.44.28.12730
22948.44.28.128/2748.44.28.129 to 48.44.28.15848.44.28.15930
23048.44.28.160/2748.44.28.161 to 48.44.28.19048.44.28.19130
23148.44.28.192/2748.44.28.193 to 48.44.28.22248.44.28.22330
23248.44.28.224/2748.44.28.225 to 48.44.28.25448.44.28.25530
23348.44.29.0/2748.44.29.1 to 48.44.29.3048.44.29.3130
23448.44.29.32/2748.44.29.33 to 48.44.29.6248.44.29.6330
23548.44.29.64/2748.44.29.65 to 48.44.29.9448.44.29.9530
23648.44.29.96/2748.44.29.97 to 48.44.29.12648.44.29.12730
23748.44.29.128/2748.44.29.129 to 48.44.29.15848.44.29.15930
23848.44.29.160/2748.44.29.161 to 48.44.29.19048.44.29.19130
23948.44.29.192/2748.44.29.193 to 48.44.29.22248.44.29.22330
24048.44.29.224/2748.44.29.225 to 48.44.29.25448.44.29.25530
24148.44.30.0/2748.44.30.1 to 48.44.30.3048.44.30.3130
24248.44.30.32/2748.44.30.33 to 48.44.30.6248.44.30.6330
24348.44.30.64/2748.44.30.65 to 48.44.30.9448.44.30.9530
24448.44.30.96/2748.44.30.97 to 48.44.30.12648.44.30.12730
24548.44.30.128/2748.44.30.129 to 48.44.30.15848.44.30.15930
24648.44.30.160/2748.44.30.161 to 48.44.30.19048.44.30.19130
24748.44.30.192/2748.44.30.193 to 48.44.30.22248.44.30.22330
24848.44.30.224/2748.44.30.225 to 48.44.30.25448.44.30.25530
24948.44.31.0/2748.44.31.1 to 48.44.31.3048.44.31.3130
25048.44.31.32/2748.44.31.33 to 48.44.31.6248.44.31.6330
25148.44.31.64/2748.44.31.65 to 48.44.31.9448.44.31.9530
25248.44.31.96/2748.44.31.97 to 48.44.31.12648.44.31.12730
25348.44.31.128/2748.44.31.129 to 48.44.31.15848.44.31.15930
25448.44.31.160/2748.44.31.161 to 48.44.31.19048.44.31.19130
25548.44.31.192/2748.44.31.193 to 48.44.31.22248.44.31.22330
25648.44.31.224/2748.44.31.225 to 48.44.31.25448.44.31.25530

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.