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.

Network87.5.0.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
87.5.0.0
Broadcast address
87.5.31.255
First usable
87.5.0.1
Last usable
87.5.31.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 57050000 · Integer 1459945472 to 1459953663
Reverse DNS zones
0.5.87.in-addr.arpa
1.5.87.in-addr.arpa
2.5.87.in-addr.arpa
3.5.87.in-addr.arpa
4.5.87.in-addr.arpa
5.5.87.in-addr.arpa
6.5.87.in-addr.arpa
7.5.87.in-addr.arpa
8.5.87.in-addr.arpa
9.5.87.in-addr.arpa
10.5.87.in-addr.arpa
11.5.87.in-addr.arpa
12.5.87.in-addr.arpa
13.5.87.in-addr.arpa
14.5.87.in-addr.arpa
15.5.87.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010111.00000101.00000000.0000000087.5.0.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network01010111.00000101.00000000.0000000087.5.0.0
Broadcast01010111.00000101.00011111.1111111187.5.31.255
Split into smaller subnets/29
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

87.5.0.0/19 makes 1,024 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
187.5.0.0/2987.5.0.1 to 87.5.0.687.5.0.76
287.5.0.8/2987.5.0.9 to 87.5.0.1487.5.0.156
387.5.0.16/2987.5.0.17 to 87.5.0.2287.5.0.236
487.5.0.24/2987.5.0.25 to 87.5.0.3087.5.0.316
587.5.0.32/2987.5.0.33 to 87.5.0.3887.5.0.396
687.5.0.40/2987.5.0.41 to 87.5.0.4687.5.0.476
787.5.0.48/2987.5.0.49 to 87.5.0.5487.5.0.556
887.5.0.56/2987.5.0.57 to 87.5.0.6287.5.0.636
987.5.0.64/2987.5.0.65 to 87.5.0.7087.5.0.716
1087.5.0.72/2987.5.0.73 to 87.5.0.7887.5.0.796
1187.5.0.80/2987.5.0.81 to 87.5.0.8687.5.0.876
1287.5.0.88/2987.5.0.89 to 87.5.0.9487.5.0.956
1387.5.0.96/2987.5.0.97 to 87.5.0.10287.5.0.1036
1487.5.0.104/2987.5.0.105 to 87.5.0.11087.5.0.1116
1587.5.0.112/2987.5.0.113 to 87.5.0.11887.5.0.1196
1687.5.0.120/2987.5.0.121 to 87.5.0.12687.5.0.1276
1787.5.0.128/2987.5.0.129 to 87.5.0.13487.5.0.1356
1887.5.0.136/2987.5.0.137 to 87.5.0.14287.5.0.1436
1987.5.0.144/2987.5.0.145 to 87.5.0.15087.5.0.1516
2087.5.0.152/2987.5.0.153 to 87.5.0.15887.5.0.1596
2187.5.0.160/2987.5.0.161 to 87.5.0.16687.5.0.1676
2287.5.0.168/2987.5.0.169 to 87.5.0.17487.5.0.1756
2387.5.0.176/2987.5.0.177 to 87.5.0.18287.5.0.1836
2487.5.0.184/2987.5.0.185 to 87.5.0.19087.5.0.1916
2587.5.0.192/2987.5.0.193 to 87.5.0.19887.5.0.1996
2687.5.0.200/2987.5.0.201 to 87.5.0.20687.5.0.2076
2787.5.0.208/2987.5.0.209 to 87.5.0.21487.5.0.2156
2887.5.0.216/2987.5.0.217 to 87.5.0.22287.5.0.2236
2987.5.0.224/2987.5.0.225 to 87.5.0.23087.5.0.2316
3087.5.0.232/2987.5.0.233 to 87.5.0.23887.5.0.2396
3187.5.0.240/2987.5.0.241 to 87.5.0.24687.5.0.2476
3287.5.0.248/2987.5.0.249 to 87.5.0.25487.5.0.2556
3387.5.1.0/2987.5.1.1 to 87.5.1.687.5.1.76
3487.5.1.8/2987.5.1.9 to 87.5.1.1487.5.1.156
3587.5.1.16/2987.5.1.17 to 87.5.1.2287.5.1.236
3687.5.1.24/2987.5.1.25 to 87.5.1.3087.5.1.316
3787.5.1.32/2987.5.1.33 to 87.5.1.3887.5.1.396
3887.5.1.40/2987.5.1.41 to 87.5.1.4687.5.1.476
3987.5.1.48/2987.5.1.49 to 87.5.1.5487.5.1.556
4087.5.1.56/2987.5.1.57 to 87.5.1.6287.5.1.636
4187.5.1.64/2987.5.1.65 to 87.5.1.7087.5.1.716
4287.5.1.72/2987.5.1.73 to 87.5.1.7887.5.1.796
4387.5.1.80/2987.5.1.81 to 87.5.1.8687.5.1.876
4487.5.1.88/2987.5.1.89 to 87.5.1.9487.5.1.956
4587.5.1.96/2987.5.1.97 to 87.5.1.10287.5.1.1036
4687.5.1.104/2987.5.1.105 to 87.5.1.11087.5.1.1116
4787.5.1.112/2987.5.1.113 to 87.5.1.11887.5.1.1196
4887.5.1.120/2987.5.1.121 to 87.5.1.12687.5.1.1276
4987.5.1.128/2987.5.1.129 to 87.5.1.13487.5.1.1356
5087.5.1.136/2987.5.1.137 to 87.5.1.14287.5.1.1436
5187.5.1.144/2987.5.1.145 to 87.5.1.15087.5.1.1516
5287.5.1.152/2987.5.1.153 to 87.5.1.15887.5.1.1596
5387.5.1.160/2987.5.1.161 to 87.5.1.16687.5.1.1676
5487.5.1.168/2987.5.1.169 to 87.5.1.17487.5.1.1756
5587.5.1.176/2987.5.1.177 to 87.5.1.18287.5.1.1836
5687.5.1.184/2987.5.1.185 to 87.5.1.19087.5.1.1916
5787.5.1.192/2987.5.1.193 to 87.5.1.19887.5.1.1996
5887.5.1.200/2987.5.1.201 to 87.5.1.20687.5.1.2076
5987.5.1.208/2987.5.1.209 to 87.5.1.21487.5.1.2156
6087.5.1.216/2987.5.1.217 to 87.5.1.22287.5.1.2236
6187.5.1.224/2987.5.1.225 to 87.5.1.23087.5.1.2316
6287.5.1.232/2987.5.1.233 to 87.5.1.23887.5.1.2396
6387.5.1.240/2987.5.1.241 to 87.5.1.24687.5.1.2476
6487.5.1.248/2987.5.1.249 to 87.5.1.25487.5.1.2556
6587.5.2.0/2987.5.2.1 to 87.5.2.687.5.2.76
6687.5.2.8/2987.5.2.9 to 87.5.2.1487.5.2.156
6787.5.2.16/2987.5.2.17 to 87.5.2.2287.5.2.236
6887.5.2.24/2987.5.2.25 to 87.5.2.3087.5.2.316
6987.5.2.32/2987.5.2.33 to 87.5.2.3887.5.2.396
7087.5.2.40/2987.5.2.41 to 87.5.2.4687.5.2.476
7187.5.2.48/2987.5.2.49 to 87.5.2.5487.5.2.556
7287.5.2.56/2987.5.2.57 to 87.5.2.6287.5.2.636
7387.5.2.64/2987.5.2.65 to 87.5.2.7087.5.2.716
7487.5.2.72/2987.5.2.73 to 87.5.2.7887.5.2.796
7587.5.2.80/2987.5.2.81 to 87.5.2.8687.5.2.876
7687.5.2.88/2987.5.2.89 to 87.5.2.9487.5.2.956
7787.5.2.96/2987.5.2.97 to 87.5.2.10287.5.2.1036
7887.5.2.104/2987.5.2.105 to 87.5.2.11087.5.2.1116
7987.5.2.112/2987.5.2.113 to 87.5.2.11887.5.2.1196
8087.5.2.120/2987.5.2.121 to 87.5.2.12687.5.2.1276
8187.5.2.128/2987.5.2.129 to 87.5.2.13487.5.2.1356
8287.5.2.136/2987.5.2.137 to 87.5.2.14287.5.2.1436
8387.5.2.144/2987.5.2.145 to 87.5.2.15087.5.2.1516
8487.5.2.152/2987.5.2.153 to 87.5.2.15887.5.2.1596
8587.5.2.160/2987.5.2.161 to 87.5.2.16687.5.2.1676
8687.5.2.168/2987.5.2.169 to 87.5.2.17487.5.2.1756
8787.5.2.176/2987.5.2.177 to 87.5.2.18287.5.2.1836
8887.5.2.184/2987.5.2.185 to 87.5.2.19087.5.2.1916
8987.5.2.192/2987.5.2.193 to 87.5.2.19887.5.2.1996
9087.5.2.200/2987.5.2.201 to 87.5.2.20687.5.2.2076
9187.5.2.208/2987.5.2.209 to 87.5.2.21487.5.2.2156
9287.5.2.216/2987.5.2.217 to 87.5.2.22287.5.2.2236
9387.5.2.224/2987.5.2.225 to 87.5.2.23087.5.2.2316
9487.5.2.232/2987.5.2.233 to 87.5.2.23887.5.2.2396
9587.5.2.240/2987.5.2.241 to 87.5.2.24687.5.2.2476
9687.5.2.248/2987.5.2.249 to 87.5.2.25487.5.2.2556
9787.5.3.0/2987.5.3.1 to 87.5.3.687.5.3.76
9887.5.3.8/2987.5.3.9 to 87.5.3.1487.5.3.156
9987.5.3.16/2987.5.3.17 to 87.5.3.2287.5.3.236
10087.5.3.24/2987.5.3.25 to 87.5.3.3087.5.3.316
10187.5.3.32/2987.5.3.33 to 87.5.3.3887.5.3.396
10287.5.3.40/2987.5.3.41 to 87.5.3.4687.5.3.476
10387.5.3.48/2987.5.3.49 to 87.5.3.5487.5.3.556
10487.5.3.56/2987.5.3.57 to 87.5.3.6287.5.3.636
10587.5.3.64/2987.5.3.65 to 87.5.3.7087.5.3.716
10687.5.3.72/2987.5.3.73 to 87.5.3.7887.5.3.796
10787.5.3.80/2987.5.3.81 to 87.5.3.8687.5.3.876
10887.5.3.88/2987.5.3.89 to 87.5.3.9487.5.3.956
10987.5.3.96/2987.5.3.97 to 87.5.3.10287.5.3.1036
11087.5.3.104/2987.5.3.105 to 87.5.3.11087.5.3.1116
11187.5.3.112/2987.5.3.113 to 87.5.3.11887.5.3.1196
11287.5.3.120/2987.5.3.121 to 87.5.3.12687.5.3.1276
11387.5.3.128/2987.5.3.129 to 87.5.3.13487.5.3.1356
11487.5.3.136/2987.5.3.137 to 87.5.3.14287.5.3.1436
11587.5.3.144/2987.5.3.145 to 87.5.3.15087.5.3.1516
11687.5.3.152/2987.5.3.153 to 87.5.3.15887.5.3.1596
11787.5.3.160/2987.5.3.161 to 87.5.3.16687.5.3.1676
11887.5.3.168/2987.5.3.169 to 87.5.3.17487.5.3.1756
11987.5.3.176/2987.5.3.177 to 87.5.3.18287.5.3.1836
12087.5.3.184/2987.5.3.185 to 87.5.3.19087.5.3.1916
12187.5.3.192/2987.5.3.193 to 87.5.3.19887.5.3.1996
12287.5.3.200/2987.5.3.201 to 87.5.3.20687.5.3.2076
12387.5.3.208/2987.5.3.209 to 87.5.3.21487.5.3.2156
12487.5.3.216/2987.5.3.217 to 87.5.3.22287.5.3.2236
12587.5.3.224/2987.5.3.225 to 87.5.3.23087.5.3.2316
12687.5.3.232/2987.5.3.233 to 87.5.3.23887.5.3.2396
12787.5.3.240/2987.5.3.241 to 87.5.3.24687.5.3.2476
12887.5.3.248/2987.5.3.249 to 87.5.3.25487.5.3.2556
12987.5.4.0/2987.5.4.1 to 87.5.4.687.5.4.76
13087.5.4.8/2987.5.4.9 to 87.5.4.1487.5.4.156
13187.5.4.16/2987.5.4.17 to 87.5.4.2287.5.4.236
13287.5.4.24/2987.5.4.25 to 87.5.4.3087.5.4.316
13387.5.4.32/2987.5.4.33 to 87.5.4.3887.5.4.396
13487.5.4.40/2987.5.4.41 to 87.5.4.4687.5.4.476
13587.5.4.48/2987.5.4.49 to 87.5.4.5487.5.4.556
13687.5.4.56/2987.5.4.57 to 87.5.4.6287.5.4.636
13787.5.4.64/2987.5.4.65 to 87.5.4.7087.5.4.716
13887.5.4.72/2987.5.4.73 to 87.5.4.7887.5.4.796
13987.5.4.80/2987.5.4.81 to 87.5.4.8687.5.4.876
14087.5.4.88/2987.5.4.89 to 87.5.4.9487.5.4.956
14187.5.4.96/2987.5.4.97 to 87.5.4.10287.5.4.1036
14287.5.4.104/2987.5.4.105 to 87.5.4.11087.5.4.1116
14387.5.4.112/2987.5.4.113 to 87.5.4.11887.5.4.1196
14487.5.4.120/2987.5.4.121 to 87.5.4.12687.5.4.1276
14587.5.4.128/2987.5.4.129 to 87.5.4.13487.5.4.1356
14687.5.4.136/2987.5.4.137 to 87.5.4.14287.5.4.1436
14787.5.4.144/2987.5.4.145 to 87.5.4.15087.5.4.1516
14887.5.4.152/2987.5.4.153 to 87.5.4.15887.5.4.1596
14987.5.4.160/2987.5.4.161 to 87.5.4.16687.5.4.1676
15087.5.4.168/2987.5.4.169 to 87.5.4.17487.5.4.1756
15187.5.4.176/2987.5.4.177 to 87.5.4.18287.5.4.1836
15287.5.4.184/2987.5.4.185 to 87.5.4.19087.5.4.1916
15387.5.4.192/2987.5.4.193 to 87.5.4.19887.5.4.1996
15487.5.4.200/2987.5.4.201 to 87.5.4.20687.5.4.2076
15587.5.4.208/2987.5.4.209 to 87.5.4.21487.5.4.2156
15687.5.4.216/2987.5.4.217 to 87.5.4.22287.5.4.2236
15787.5.4.224/2987.5.4.225 to 87.5.4.23087.5.4.2316
15887.5.4.232/2987.5.4.233 to 87.5.4.23887.5.4.2396
15987.5.4.240/2987.5.4.241 to 87.5.4.24687.5.4.2476
16087.5.4.248/2987.5.4.249 to 87.5.4.25487.5.4.2556
16187.5.5.0/2987.5.5.1 to 87.5.5.687.5.5.76
16287.5.5.8/2987.5.5.9 to 87.5.5.1487.5.5.156
16387.5.5.16/2987.5.5.17 to 87.5.5.2287.5.5.236
16487.5.5.24/2987.5.5.25 to 87.5.5.3087.5.5.316
16587.5.5.32/2987.5.5.33 to 87.5.5.3887.5.5.396
16687.5.5.40/2987.5.5.41 to 87.5.5.4687.5.5.476
16787.5.5.48/2987.5.5.49 to 87.5.5.5487.5.5.556
16887.5.5.56/2987.5.5.57 to 87.5.5.6287.5.5.636
16987.5.5.64/2987.5.5.65 to 87.5.5.7087.5.5.716
17087.5.5.72/2987.5.5.73 to 87.5.5.7887.5.5.796
17187.5.5.80/2987.5.5.81 to 87.5.5.8687.5.5.876
17287.5.5.88/2987.5.5.89 to 87.5.5.9487.5.5.956
17387.5.5.96/2987.5.5.97 to 87.5.5.10287.5.5.1036
17487.5.5.104/2987.5.5.105 to 87.5.5.11087.5.5.1116
17587.5.5.112/2987.5.5.113 to 87.5.5.11887.5.5.1196
17687.5.5.120/2987.5.5.121 to 87.5.5.12687.5.5.1276
17787.5.5.128/2987.5.5.129 to 87.5.5.13487.5.5.1356
17887.5.5.136/2987.5.5.137 to 87.5.5.14287.5.5.1436
17987.5.5.144/2987.5.5.145 to 87.5.5.15087.5.5.1516
18087.5.5.152/2987.5.5.153 to 87.5.5.15887.5.5.1596
18187.5.5.160/2987.5.5.161 to 87.5.5.16687.5.5.1676
18287.5.5.168/2987.5.5.169 to 87.5.5.17487.5.5.1756
18387.5.5.176/2987.5.5.177 to 87.5.5.18287.5.5.1836
18487.5.5.184/2987.5.5.185 to 87.5.5.19087.5.5.1916
18587.5.5.192/2987.5.5.193 to 87.5.5.19887.5.5.1996
18687.5.5.200/2987.5.5.201 to 87.5.5.20687.5.5.2076
18787.5.5.208/2987.5.5.209 to 87.5.5.21487.5.5.2156
18887.5.5.216/2987.5.5.217 to 87.5.5.22287.5.5.2236
18987.5.5.224/2987.5.5.225 to 87.5.5.23087.5.5.2316
19087.5.5.232/2987.5.5.233 to 87.5.5.23887.5.5.2396
19187.5.5.240/2987.5.5.241 to 87.5.5.24687.5.5.2476
19287.5.5.248/2987.5.5.249 to 87.5.5.25487.5.5.2556
19387.5.6.0/2987.5.6.1 to 87.5.6.687.5.6.76
19487.5.6.8/2987.5.6.9 to 87.5.6.1487.5.6.156
19587.5.6.16/2987.5.6.17 to 87.5.6.2287.5.6.236
19687.5.6.24/2987.5.6.25 to 87.5.6.3087.5.6.316
19787.5.6.32/2987.5.6.33 to 87.5.6.3887.5.6.396
19887.5.6.40/2987.5.6.41 to 87.5.6.4687.5.6.476
19987.5.6.48/2987.5.6.49 to 87.5.6.5487.5.6.556
20087.5.6.56/2987.5.6.57 to 87.5.6.6287.5.6.636
20187.5.6.64/2987.5.6.65 to 87.5.6.7087.5.6.716
20287.5.6.72/2987.5.6.73 to 87.5.6.7887.5.6.796
20387.5.6.80/2987.5.6.81 to 87.5.6.8687.5.6.876
20487.5.6.88/2987.5.6.89 to 87.5.6.9487.5.6.956
20587.5.6.96/2987.5.6.97 to 87.5.6.10287.5.6.1036
20687.5.6.104/2987.5.6.105 to 87.5.6.11087.5.6.1116
20787.5.6.112/2987.5.6.113 to 87.5.6.11887.5.6.1196
20887.5.6.120/2987.5.6.121 to 87.5.6.12687.5.6.1276
20987.5.6.128/2987.5.6.129 to 87.5.6.13487.5.6.1356
21087.5.6.136/2987.5.6.137 to 87.5.6.14287.5.6.1436
21187.5.6.144/2987.5.6.145 to 87.5.6.15087.5.6.1516
21287.5.6.152/2987.5.6.153 to 87.5.6.15887.5.6.1596
21387.5.6.160/2987.5.6.161 to 87.5.6.16687.5.6.1676
21487.5.6.168/2987.5.6.169 to 87.5.6.17487.5.6.1756
21587.5.6.176/2987.5.6.177 to 87.5.6.18287.5.6.1836
21687.5.6.184/2987.5.6.185 to 87.5.6.19087.5.6.1916
21787.5.6.192/2987.5.6.193 to 87.5.6.19887.5.6.1996
21887.5.6.200/2987.5.6.201 to 87.5.6.20687.5.6.2076
21987.5.6.208/2987.5.6.209 to 87.5.6.21487.5.6.2156
22087.5.6.216/2987.5.6.217 to 87.5.6.22287.5.6.2236
22187.5.6.224/2987.5.6.225 to 87.5.6.23087.5.6.2316
22287.5.6.232/2987.5.6.233 to 87.5.6.23887.5.6.2396
22387.5.6.240/2987.5.6.241 to 87.5.6.24687.5.6.2476
22487.5.6.248/2987.5.6.249 to 87.5.6.25487.5.6.2556
22587.5.7.0/2987.5.7.1 to 87.5.7.687.5.7.76
22687.5.7.8/2987.5.7.9 to 87.5.7.1487.5.7.156
22787.5.7.16/2987.5.7.17 to 87.5.7.2287.5.7.236
22887.5.7.24/2987.5.7.25 to 87.5.7.3087.5.7.316
22987.5.7.32/2987.5.7.33 to 87.5.7.3887.5.7.396
23087.5.7.40/2987.5.7.41 to 87.5.7.4687.5.7.476
23187.5.7.48/2987.5.7.49 to 87.5.7.5487.5.7.556
23287.5.7.56/2987.5.7.57 to 87.5.7.6287.5.7.636
23387.5.7.64/2987.5.7.65 to 87.5.7.7087.5.7.716
23487.5.7.72/2987.5.7.73 to 87.5.7.7887.5.7.796
23587.5.7.80/2987.5.7.81 to 87.5.7.8687.5.7.876
23687.5.7.88/2987.5.7.89 to 87.5.7.9487.5.7.956
23787.5.7.96/2987.5.7.97 to 87.5.7.10287.5.7.1036
23887.5.7.104/2987.5.7.105 to 87.5.7.11087.5.7.1116
23987.5.7.112/2987.5.7.113 to 87.5.7.11887.5.7.1196
24087.5.7.120/2987.5.7.121 to 87.5.7.12687.5.7.1276
24187.5.7.128/2987.5.7.129 to 87.5.7.13487.5.7.1356
24287.5.7.136/2987.5.7.137 to 87.5.7.14287.5.7.1436
24387.5.7.144/2987.5.7.145 to 87.5.7.15087.5.7.1516
24487.5.7.152/2987.5.7.153 to 87.5.7.15887.5.7.1596
24587.5.7.160/2987.5.7.161 to 87.5.7.16687.5.7.1676
24687.5.7.168/2987.5.7.169 to 87.5.7.17487.5.7.1756
24787.5.7.176/2987.5.7.177 to 87.5.7.18287.5.7.1836
24887.5.7.184/2987.5.7.185 to 87.5.7.19087.5.7.1916
24987.5.7.192/2987.5.7.193 to 87.5.7.19887.5.7.1996
25087.5.7.200/2987.5.7.201 to 87.5.7.20687.5.7.2076
25187.5.7.208/2987.5.7.209 to 87.5.7.21487.5.7.2156
25287.5.7.216/2987.5.7.217 to 87.5.7.22287.5.7.2236
25387.5.7.224/2987.5.7.225 to 87.5.7.23087.5.7.2316
25487.5.7.232/2987.5.7.233 to 87.5.7.23887.5.7.2396
25587.5.7.240/2987.5.7.241 to 87.5.7.24687.5.7.2476
25687.5.7.248/2987.5.7.249 to 87.5.7.25487.5.7.2556

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.