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.

Network64.3.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
64.3.64.0
Broadcast address
64.3.127.255
First usable
64.3.64.1
Last usable
64.3.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
A (default /8)
As numbers
Hex 40034000 · Integer 1073954816 to 1073971199
Reverse DNS zones
64.3.64.in-addr.arpa
65.3.64.in-addr.arpa
66.3.64.in-addr.arpa
67.3.64.in-addr.arpa
68.3.64.in-addr.arpa
69.3.64.in-addr.arpa
70.3.64.in-addr.arpa
71.3.64.in-addr.arpa
72.3.64.in-addr.arpa
73.3.64.in-addr.arpa
74.3.64.in-addr.arpa
75.3.64.in-addr.arpa
76.3.64.in-addr.arpa
77.3.64.in-addr.arpa
78.3.64.in-addr.arpa
79.3.64.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000000.00000011.01000000.0000000064.3.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network01000000.00000011.01000000.0000000064.3.64.0
Broadcast01000000.00000011.01111111.1111111164.3.127.255
Split into smaller subnets/30
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

64.3.64.0/18 makes 4,096 subnets of /30; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.3.64.0/3064.3.64.1 to 64.3.64.264.3.64.32
264.3.64.4/3064.3.64.5 to 64.3.64.664.3.64.72
364.3.64.8/3064.3.64.9 to 64.3.64.1064.3.64.112
464.3.64.12/3064.3.64.13 to 64.3.64.1464.3.64.152
564.3.64.16/3064.3.64.17 to 64.3.64.1864.3.64.192
664.3.64.20/3064.3.64.21 to 64.3.64.2264.3.64.232
764.3.64.24/3064.3.64.25 to 64.3.64.2664.3.64.272
864.3.64.28/3064.3.64.29 to 64.3.64.3064.3.64.312
964.3.64.32/3064.3.64.33 to 64.3.64.3464.3.64.352
1064.3.64.36/3064.3.64.37 to 64.3.64.3864.3.64.392
1164.3.64.40/3064.3.64.41 to 64.3.64.4264.3.64.432
1264.3.64.44/3064.3.64.45 to 64.3.64.4664.3.64.472
1364.3.64.48/3064.3.64.49 to 64.3.64.5064.3.64.512
1464.3.64.52/3064.3.64.53 to 64.3.64.5464.3.64.552
1564.3.64.56/3064.3.64.57 to 64.3.64.5864.3.64.592
1664.3.64.60/3064.3.64.61 to 64.3.64.6264.3.64.632
1764.3.64.64/3064.3.64.65 to 64.3.64.6664.3.64.672
1864.3.64.68/3064.3.64.69 to 64.3.64.7064.3.64.712
1964.3.64.72/3064.3.64.73 to 64.3.64.7464.3.64.752
2064.3.64.76/3064.3.64.77 to 64.3.64.7864.3.64.792
2164.3.64.80/3064.3.64.81 to 64.3.64.8264.3.64.832
2264.3.64.84/3064.3.64.85 to 64.3.64.8664.3.64.872
2364.3.64.88/3064.3.64.89 to 64.3.64.9064.3.64.912
2464.3.64.92/3064.3.64.93 to 64.3.64.9464.3.64.952
2564.3.64.96/3064.3.64.97 to 64.3.64.9864.3.64.992
2664.3.64.100/3064.3.64.101 to 64.3.64.10264.3.64.1032
2764.3.64.104/3064.3.64.105 to 64.3.64.10664.3.64.1072
2864.3.64.108/3064.3.64.109 to 64.3.64.11064.3.64.1112
2964.3.64.112/3064.3.64.113 to 64.3.64.11464.3.64.1152
3064.3.64.116/3064.3.64.117 to 64.3.64.11864.3.64.1192
3164.3.64.120/3064.3.64.121 to 64.3.64.12264.3.64.1232
3264.3.64.124/3064.3.64.125 to 64.3.64.12664.3.64.1272
3364.3.64.128/3064.3.64.129 to 64.3.64.13064.3.64.1312
3464.3.64.132/3064.3.64.133 to 64.3.64.13464.3.64.1352
3564.3.64.136/3064.3.64.137 to 64.3.64.13864.3.64.1392
3664.3.64.140/3064.3.64.141 to 64.3.64.14264.3.64.1432
3764.3.64.144/3064.3.64.145 to 64.3.64.14664.3.64.1472
3864.3.64.148/3064.3.64.149 to 64.3.64.15064.3.64.1512
3964.3.64.152/3064.3.64.153 to 64.3.64.15464.3.64.1552
4064.3.64.156/3064.3.64.157 to 64.3.64.15864.3.64.1592
4164.3.64.160/3064.3.64.161 to 64.3.64.16264.3.64.1632
4264.3.64.164/3064.3.64.165 to 64.3.64.16664.3.64.1672
4364.3.64.168/3064.3.64.169 to 64.3.64.17064.3.64.1712
4464.3.64.172/3064.3.64.173 to 64.3.64.17464.3.64.1752
4564.3.64.176/3064.3.64.177 to 64.3.64.17864.3.64.1792
4664.3.64.180/3064.3.64.181 to 64.3.64.18264.3.64.1832
4764.3.64.184/3064.3.64.185 to 64.3.64.18664.3.64.1872
4864.3.64.188/3064.3.64.189 to 64.3.64.19064.3.64.1912
4964.3.64.192/3064.3.64.193 to 64.3.64.19464.3.64.1952
5064.3.64.196/3064.3.64.197 to 64.3.64.19864.3.64.1992
5164.3.64.200/3064.3.64.201 to 64.3.64.20264.3.64.2032
5264.3.64.204/3064.3.64.205 to 64.3.64.20664.3.64.2072
5364.3.64.208/3064.3.64.209 to 64.3.64.21064.3.64.2112
5464.3.64.212/3064.3.64.213 to 64.3.64.21464.3.64.2152
5564.3.64.216/3064.3.64.217 to 64.3.64.21864.3.64.2192
5664.3.64.220/3064.3.64.221 to 64.3.64.22264.3.64.2232
5764.3.64.224/3064.3.64.225 to 64.3.64.22664.3.64.2272
5864.3.64.228/3064.3.64.229 to 64.3.64.23064.3.64.2312
5964.3.64.232/3064.3.64.233 to 64.3.64.23464.3.64.2352
6064.3.64.236/3064.3.64.237 to 64.3.64.23864.3.64.2392
6164.3.64.240/3064.3.64.241 to 64.3.64.24264.3.64.2432
6264.3.64.244/3064.3.64.245 to 64.3.64.24664.3.64.2472
6364.3.64.248/3064.3.64.249 to 64.3.64.25064.3.64.2512
6464.3.64.252/3064.3.64.253 to 64.3.64.25464.3.64.2552
6564.3.65.0/3064.3.65.1 to 64.3.65.264.3.65.32
6664.3.65.4/3064.3.65.5 to 64.3.65.664.3.65.72
6764.3.65.8/3064.3.65.9 to 64.3.65.1064.3.65.112
6864.3.65.12/3064.3.65.13 to 64.3.65.1464.3.65.152
6964.3.65.16/3064.3.65.17 to 64.3.65.1864.3.65.192
7064.3.65.20/3064.3.65.21 to 64.3.65.2264.3.65.232
7164.3.65.24/3064.3.65.25 to 64.3.65.2664.3.65.272
7264.3.65.28/3064.3.65.29 to 64.3.65.3064.3.65.312
7364.3.65.32/3064.3.65.33 to 64.3.65.3464.3.65.352
7464.3.65.36/3064.3.65.37 to 64.3.65.3864.3.65.392
7564.3.65.40/3064.3.65.41 to 64.3.65.4264.3.65.432
7664.3.65.44/3064.3.65.45 to 64.3.65.4664.3.65.472
7764.3.65.48/3064.3.65.49 to 64.3.65.5064.3.65.512
7864.3.65.52/3064.3.65.53 to 64.3.65.5464.3.65.552
7964.3.65.56/3064.3.65.57 to 64.3.65.5864.3.65.592
8064.3.65.60/3064.3.65.61 to 64.3.65.6264.3.65.632
8164.3.65.64/3064.3.65.65 to 64.3.65.6664.3.65.672
8264.3.65.68/3064.3.65.69 to 64.3.65.7064.3.65.712
8364.3.65.72/3064.3.65.73 to 64.3.65.7464.3.65.752
8464.3.65.76/3064.3.65.77 to 64.3.65.7864.3.65.792
8564.3.65.80/3064.3.65.81 to 64.3.65.8264.3.65.832
8664.3.65.84/3064.3.65.85 to 64.3.65.8664.3.65.872
8764.3.65.88/3064.3.65.89 to 64.3.65.9064.3.65.912
8864.3.65.92/3064.3.65.93 to 64.3.65.9464.3.65.952
8964.3.65.96/3064.3.65.97 to 64.3.65.9864.3.65.992
9064.3.65.100/3064.3.65.101 to 64.3.65.10264.3.65.1032
9164.3.65.104/3064.3.65.105 to 64.3.65.10664.3.65.1072
9264.3.65.108/3064.3.65.109 to 64.3.65.11064.3.65.1112
9364.3.65.112/3064.3.65.113 to 64.3.65.11464.3.65.1152
9464.3.65.116/3064.3.65.117 to 64.3.65.11864.3.65.1192
9564.3.65.120/3064.3.65.121 to 64.3.65.12264.3.65.1232
9664.3.65.124/3064.3.65.125 to 64.3.65.12664.3.65.1272
9764.3.65.128/3064.3.65.129 to 64.3.65.13064.3.65.1312
9864.3.65.132/3064.3.65.133 to 64.3.65.13464.3.65.1352
9964.3.65.136/3064.3.65.137 to 64.3.65.13864.3.65.1392
10064.3.65.140/3064.3.65.141 to 64.3.65.14264.3.65.1432
10164.3.65.144/3064.3.65.145 to 64.3.65.14664.3.65.1472
10264.3.65.148/3064.3.65.149 to 64.3.65.15064.3.65.1512
10364.3.65.152/3064.3.65.153 to 64.3.65.15464.3.65.1552
10464.3.65.156/3064.3.65.157 to 64.3.65.15864.3.65.1592
10564.3.65.160/3064.3.65.161 to 64.3.65.16264.3.65.1632
10664.3.65.164/3064.3.65.165 to 64.3.65.16664.3.65.1672
10764.3.65.168/3064.3.65.169 to 64.3.65.17064.3.65.1712
10864.3.65.172/3064.3.65.173 to 64.3.65.17464.3.65.1752
10964.3.65.176/3064.3.65.177 to 64.3.65.17864.3.65.1792
11064.3.65.180/3064.3.65.181 to 64.3.65.18264.3.65.1832
11164.3.65.184/3064.3.65.185 to 64.3.65.18664.3.65.1872
11264.3.65.188/3064.3.65.189 to 64.3.65.19064.3.65.1912
11364.3.65.192/3064.3.65.193 to 64.3.65.19464.3.65.1952
11464.3.65.196/3064.3.65.197 to 64.3.65.19864.3.65.1992
11564.3.65.200/3064.3.65.201 to 64.3.65.20264.3.65.2032
11664.3.65.204/3064.3.65.205 to 64.3.65.20664.3.65.2072
11764.3.65.208/3064.3.65.209 to 64.3.65.21064.3.65.2112
11864.3.65.212/3064.3.65.213 to 64.3.65.21464.3.65.2152
11964.3.65.216/3064.3.65.217 to 64.3.65.21864.3.65.2192
12064.3.65.220/3064.3.65.221 to 64.3.65.22264.3.65.2232
12164.3.65.224/3064.3.65.225 to 64.3.65.22664.3.65.2272
12264.3.65.228/3064.3.65.229 to 64.3.65.23064.3.65.2312
12364.3.65.232/3064.3.65.233 to 64.3.65.23464.3.65.2352
12464.3.65.236/3064.3.65.237 to 64.3.65.23864.3.65.2392
12564.3.65.240/3064.3.65.241 to 64.3.65.24264.3.65.2432
12664.3.65.244/3064.3.65.245 to 64.3.65.24664.3.65.2472
12764.3.65.248/3064.3.65.249 to 64.3.65.25064.3.65.2512
12864.3.65.252/3064.3.65.253 to 64.3.65.25464.3.65.2552
12964.3.66.0/3064.3.66.1 to 64.3.66.264.3.66.32
13064.3.66.4/3064.3.66.5 to 64.3.66.664.3.66.72
13164.3.66.8/3064.3.66.9 to 64.3.66.1064.3.66.112
13264.3.66.12/3064.3.66.13 to 64.3.66.1464.3.66.152
13364.3.66.16/3064.3.66.17 to 64.3.66.1864.3.66.192
13464.3.66.20/3064.3.66.21 to 64.3.66.2264.3.66.232
13564.3.66.24/3064.3.66.25 to 64.3.66.2664.3.66.272
13664.3.66.28/3064.3.66.29 to 64.3.66.3064.3.66.312
13764.3.66.32/3064.3.66.33 to 64.3.66.3464.3.66.352
13864.3.66.36/3064.3.66.37 to 64.3.66.3864.3.66.392
13964.3.66.40/3064.3.66.41 to 64.3.66.4264.3.66.432
14064.3.66.44/3064.3.66.45 to 64.3.66.4664.3.66.472
14164.3.66.48/3064.3.66.49 to 64.3.66.5064.3.66.512
14264.3.66.52/3064.3.66.53 to 64.3.66.5464.3.66.552
14364.3.66.56/3064.3.66.57 to 64.3.66.5864.3.66.592
14464.3.66.60/3064.3.66.61 to 64.3.66.6264.3.66.632
14564.3.66.64/3064.3.66.65 to 64.3.66.6664.3.66.672
14664.3.66.68/3064.3.66.69 to 64.3.66.7064.3.66.712
14764.3.66.72/3064.3.66.73 to 64.3.66.7464.3.66.752
14864.3.66.76/3064.3.66.77 to 64.3.66.7864.3.66.792
14964.3.66.80/3064.3.66.81 to 64.3.66.8264.3.66.832
15064.3.66.84/3064.3.66.85 to 64.3.66.8664.3.66.872
15164.3.66.88/3064.3.66.89 to 64.3.66.9064.3.66.912
15264.3.66.92/3064.3.66.93 to 64.3.66.9464.3.66.952
15364.3.66.96/3064.3.66.97 to 64.3.66.9864.3.66.992
15464.3.66.100/3064.3.66.101 to 64.3.66.10264.3.66.1032
15564.3.66.104/3064.3.66.105 to 64.3.66.10664.3.66.1072
15664.3.66.108/3064.3.66.109 to 64.3.66.11064.3.66.1112
15764.3.66.112/3064.3.66.113 to 64.3.66.11464.3.66.1152
15864.3.66.116/3064.3.66.117 to 64.3.66.11864.3.66.1192
15964.3.66.120/3064.3.66.121 to 64.3.66.12264.3.66.1232
16064.3.66.124/3064.3.66.125 to 64.3.66.12664.3.66.1272
16164.3.66.128/3064.3.66.129 to 64.3.66.13064.3.66.1312
16264.3.66.132/3064.3.66.133 to 64.3.66.13464.3.66.1352
16364.3.66.136/3064.3.66.137 to 64.3.66.13864.3.66.1392
16464.3.66.140/3064.3.66.141 to 64.3.66.14264.3.66.1432
16564.3.66.144/3064.3.66.145 to 64.3.66.14664.3.66.1472
16664.3.66.148/3064.3.66.149 to 64.3.66.15064.3.66.1512
16764.3.66.152/3064.3.66.153 to 64.3.66.15464.3.66.1552
16864.3.66.156/3064.3.66.157 to 64.3.66.15864.3.66.1592
16964.3.66.160/3064.3.66.161 to 64.3.66.16264.3.66.1632
17064.3.66.164/3064.3.66.165 to 64.3.66.16664.3.66.1672
17164.3.66.168/3064.3.66.169 to 64.3.66.17064.3.66.1712
17264.3.66.172/3064.3.66.173 to 64.3.66.17464.3.66.1752
17364.3.66.176/3064.3.66.177 to 64.3.66.17864.3.66.1792
17464.3.66.180/3064.3.66.181 to 64.3.66.18264.3.66.1832
17564.3.66.184/3064.3.66.185 to 64.3.66.18664.3.66.1872
17664.3.66.188/3064.3.66.189 to 64.3.66.19064.3.66.1912
17764.3.66.192/3064.3.66.193 to 64.3.66.19464.3.66.1952
17864.3.66.196/3064.3.66.197 to 64.3.66.19864.3.66.1992
17964.3.66.200/3064.3.66.201 to 64.3.66.20264.3.66.2032
18064.3.66.204/3064.3.66.205 to 64.3.66.20664.3.66.2072
18164.3.66.208/3064.3.66.209 to 64.3.66.21064.3.66.2112
18264.3.66.212/3064.3.66.213 to 64.3.66.21464.3.66.2152
18364.3.66.216/3064.3.66.217 to 64.3.66.21864.3.66.2192
18464.3.66.220/3064.3.66.221 to 64.3.66.22264.3.66.2232
18564.3.66.224/3064.3.66.225 to 64.3.66.22664.3.66.2272
18664.3.66.228/3064.3.66.229 to 64.3.66.23064.3.66.2312
18764.3.66.232/3064.3.66.233 to 64.3.66.23464.3.66.2352
18864.3.66.236/3064.3.66.237 to 64.3.66.23864.3.66.2392
18964.3.66.240/3064.3.66.241 to 64.3.66.24264.3.66.2432
19064.3.66.244/3064.3.66.245 to 64.3.66.24664.3.66.2472
19164.3.66.248/3064.3.66.249 to 64.3.66.25064.3.66.2512
19264.3.66.252/3064.3.66.253 to 64.3.66.25464.3.66.2552
19364.3.67.0/3064.3.67.1 to 64.3.67.264.3.67.32
19464.3.67.4/3064.3.67.5 to 64.3.67.664.3.67.72
19564.3.67.8/3064.3.67.9 to 64.3.67.1064.3.67.112
19664.3.67.12/3064.3.67.13 to 64.3.67.1464.3.67.152
19764.3.67.16/3064.3.67.17 to 64.3.67.1864.3.67.192
19864.3.67.20/3064.3.67.21 to 64.3.67.2264.3.67.232
19964.3.67.24/3064.3.67.25 to 64.3.67.2664.3.67.272
20064.3.67.28/3064.3.67.29 to 64.3.67.3064.3.67.312
20164.3.67.32/3064.3.67.33 to 64.3.67.3464.3.67.352
20264.3.67.36/3064.3.67.37 to 64.3.67.3864.3.67.392
20364.3.67.40/3064.3.67.41 to 64.3.67.4264.3.67.432
20464.3.67.44/3064.3.67.45 to 64.3.67.4664.3.67.472
20564.3.67.48/3064.3.67.49 to 64.3.67.5064.3.67.512
20664.3.67.52/3064.3.67.53 to 64.3.67.5464.3.67.552
20764.3.67.56/3064.3.67.57 to 64.3.67.5864.3.67.592
20864.3.67.60/3064.3.67.61 to 64.3.67.6264.3.67.632
20964.3.67.64/3064.3.67.65 to 64.3.67.6664.3.67.672
21064.3.67.68/3064.3.67.69 to 64.3.67.7064.3.67.712
21164.3.67.72/3064.3.67.73 to 64.3.67.7464.3.67.752
21264.3.67.76/3064.3.67.77 to 64.3.67.7864.3.67.792
21364.3.67.80/3064.3.67.81 to 64.3.67.8264.3.67.832
21464.3.67.84/3064.3.67.85 to 64.3.67.8664.3.67.872
21564.3.67.88/3064.3.67.89 to 64.3.67.9064.3.67.912
21664.3.67.92/3064.3.67.93 to 64.3.67.9464.3.67.952
21764.3.67.96/3064.3.67.97 to 64.3.67.9864.3.67.992
21864.3.67.100/3064.3.67.101 to 64.3.67.10264.3.67.1032
21964.3.67.104/3064.3.67.105 to 64.3.67.10664.3.67.1072
22064.3.67.108/3064.3.67.109 to 64.3.67.11064.3.67.1112
22164.3.67.112/3064.3.67.113 to 64.3.67.11464.3.67.1152
22264.3.67.116/3064.3.67.117 to 64.3.67.11864.3.67.1192
22364.3.67.120/3064.3.67.121 to 64.3.67.12264.3.67.1232
22464.3.67.124/3064.3.67.125 to 64.3.67.12664.3.67.1272
22564.3.67.128/3064.3.67.129 to 64.3.67.13064.3.67.1312
22664.3.67.132/3064.3.67.133 to 64.3.67.13464.3.67.1352
22764.3.67.136/3064.3.67.137 to 64.3.67.13864.3.67.1392
22864.3.67.140/3064.3.67.141 to 64.3.67.14264.3.67.1432
22964.3.67.144/3064.3.67.145 to 64.3.67.14664.3.67.1472
23064.3.67.148/3064.3.67.149 to 64.3.67.15064.3.67.1512
23164.3.67.152/3064.3.67.153 to 64.3.67.15464.3.67.1552
23264.3.67.156/3064.3.67.157 to 64.3.67.15864.3.67.1592
23364.3.67.160/3064.3.67.161 to 64.3.67.16264.3.67.1632
23464.3.67.164/3064.3.67.165 to 64.3.67.16664.3.67.1672
23564.3.67.168/3064.3.67.169 to 64.3.67.17064.3.67.1712
23664.3.67.172/3064.3.67.173 to 64.3.67.17464.3.67.1752
23764.3.67.176/3064.3.67.177 to 64.3.67.17864.3.67.1792
23864.3.67.180/3064.3.67.181 to 64.3.67.18264.3.67.1832
23964.3.67.184/3064.3.67.185 to 64.3.67.18664.3.67.1872
24064.3.67.188/3064.3.67.189 to 64.3.67.19064.3.67.1912
24164.3.67.192/3064.3.67.193 to 64.3.67.19464.3.67.1952
24264.3.67.196/3064.3.67.197 to 64.3.67.19864.3.67.1992
24364.3.67.200/3064.3.67.201 to 64.3.67.20264.3.67.2032
24464.3.67.204/3064.3.67.205 to 64.3.67.20664.3.67.2072
24564.3.67.208/3064.3.67.209 to 64.3.67.21064.3.67.2112
24664.3.67.212/3064.3.67.213 to 64.3.67.21464.3.67.2152
24764.3.67.216/3064.3.67.217 to 64.3.67.21864.3.67.2192
24864.3.67.220/3064.3.67.221 to 64.3.67.22264.3.67.2232
24964.3.67.224/3064.3.67.225 to 64.3.67.22664.3.67.2272
25064.3.67.228/3064.3.67.229 to 64.3.67.23064.3.67.2312
25164.3.67.232/3064.3.67.233 to 64.3.67.23464.3.67.2352
25264.3.67.236/3064.3.67.237 to 64.3.67.23864.3.67.2392
25364.3.67.240/3064.3.67.241 to 64.3.67.24264.3.67.2432
25464.3.67.244/3064.3.67.245 to 64.3.67.24664.3.67.2472
25564.3.67.248/3064.3.67.249 to 64.3.67.25064.3.67.2512
25664.3.67.252/3064.3.67.253 to 64.3.67.25464.3.67.2552

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.