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.

Prefix/16
Addresses2^112
/64 networks2^48
Network
ffec::/16
First address
ffec::
Last address
ffec:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
ffec:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
c.e.f.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ffec::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1ffec::/24ffec:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ffec:100::/24ffec:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ffec:200::/24ffec:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ffec:300::/24ffec:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ffec:400::/24ffec:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ffec:500::/24ffec:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ffec:600::/24ffec:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ffec:700::/24ffec:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ffec:800::/24ffec:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ffec:900::/24ffec:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ffec:a00::/24ffec:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ffec:b00::/24ffec:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ffec:c00::/24ffec:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ffec:d00::/24ffec:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ffec:e00::/24ffec:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ffec:f00::/24ffec:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ffec:1000::/24ffec:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ffec:1100::/24ffec:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ffec:1200::/24ffec:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ffec:1300::/24ffec:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ffec:1400::/24ffec:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ffec:1500::/24ffec:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ffec:1600::/24ffec:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ffec:1700::/24ffec:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ffec:1800::/24ffec:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ffec:1900::/24ffec:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ffec:1a00::/24ffec:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ffec:1b00::/24ffec:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ffec:1c00::/24ffec:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ffec:1d00::/24ffec:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ffec:1e00::/24ffec:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ffec:1f00::/24ffec:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ffec:2000::/24ffec:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ffec:2100::/24ffec:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ffec:2200::/24ffec:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ffec:2300::/24ffec:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ffec:2400::/24ffec:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ffec:2500::/24ffec:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ffec:2600::/24ffec:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ffec:2700::/24ffec:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ffec:2800::/24ffec:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ffec:2900::/24ffec:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ffec:2a00::/24ffec:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ffec:2b00::/24ffec:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ffec:2c00::/24ffec:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ffec:2d00::/24ffec:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ffec:2e00::/24ffec:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ffec:2f00::/24ffec:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ffec:3000::/24ffec:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ffec:3100::/24ffec:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ffec:3200::/24ffec:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ffec:3300::/24ffec:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ffec:3400::/24ffec:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ffec:3500::/24ffec:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ffec:3600::/24ffec:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ffec:3700::/24ffec:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ffec:3800::/24ffec:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ffec:3900::/24ffec:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ffec:3a00::/24ffec:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ffec:3b00::/24ffec:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ffec:3c00::/24ffec:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ffec:3d00::/24ffec:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ffec:3e00::/24ffec:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ffec:3f00::/24ffec:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ffec:4000::/24ffec:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ffec:4100::/24ffec:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ffec:4200::/24ffec:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ffec:4300::/24ffec:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ffec:4400::/24ffec:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ffec:4500::/24ffec:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ffec:4600::/24ffec:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ffec:4700::/24ffec:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ffec:4800::/24ffec:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ffec:4900::/24ffec:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ffec:4a00::/24ffec:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ffec:4b00::/24ffec:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ffec:4c00::/24ffec:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ffec:4d00::/24ffec:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ffec:4e00::/24ffec:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ffec:4f00::/24ffec:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ffec:5000::/24ffec:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ffec:5100::/24ffec:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ffec:5200::/24ffec:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ffec:5300::/24ffec:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ffec:5400::/24ffec:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ffec:5500::/24ffec:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ffec:5600::/24ffec:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ffec:5700::/24ffec:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ffec:5800::/24ffec:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ffec:5900::/24ffec:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ffec:5a00::/24ffec:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ffec:5b00::/24ffec:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ffec:5c00::/24ffec:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ffec:5d00::/24ffec:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ffec:5e00::/24ffec:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ffec:5f00::/24ffec:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ffec:6000::/24ffec:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ffec:6100::/24ffec:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ffec:6200::/24ffec:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ffec:6300::/24ffec:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ffec:6400::/24ffec:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ffec:6500::/24ffec:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ffec:6600::/24ffec:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ffec:6700::/24ffec:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ffec:6800::/24ffec:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ffec:6900::/24ffec:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ffec:6a00::/24ffec:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ffec:6b00::/24ffec:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ffec:6c00::/24ffec:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ffec:6d00::/24ffec:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ffec:6e00::/24ffec:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ffec:6f00::/24ffec:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ffec:7000::/24ffec:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ffec:7100::/24ffec:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ffec:7200::/24ffec:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ffec:7300::/24ffec:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ffec:7400::/24ffec:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ffec:7500::/24ffec:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ffec:7600::/24ffec:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ffec:7700::/24ffec:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ffec:7800::/24ffec:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ffec:7900::/24ffec:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ffec:7a00::/24ffec:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ffec:7b00::/24ffec:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ffec:7c00::/24ffec:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ffec:7d00::/24ffec:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ffec:7e00::/24ffec:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ffec:7f00::/24ffec:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129ffec:8000::/24ffec:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130ffec:8100::/24ffec:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131ffec:8200::/24ffec:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132ffec:8300::/24ffec:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133ffec:8400::/24ffec:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134ffec:8500::/24ffec:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135ffec:8600::/24ffec:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136ffec:8700::/24ffec:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137ffec:8800::/24ffec:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138ffec:8900::/24ffec:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139ffec:8a00::/24ffec:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140ffec:8b00::/24ffec:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141ffec:8c00::/24ffec:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142ffec:8d00::/24ffec:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143ffec:8e00::/24ffec:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144ffec:8f00::/24ffec:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145ffec:9000::/24ffec:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146ffec:9100::/24ffec:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147ffec:9200::/24ffec:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148ffec:9300::/24ffec:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149ffec:9400::/24ffec:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150ffec:9500::/24ffec:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151ffec:9600::/24ffec:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152ffec:9700::/24ffec:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153ffec:9800::/24ffec:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154ffec:9900::/24ffec:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155ffec:9a00::/24ffec:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156ffec:9b00::/24ffec:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157ffec:9c00::/24ffec:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158ffec:9d00::/24ffec:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159ffec:9e00::/24ffec:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160ffec:9f00::/24ffec:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161ffec:a000::/24ffec:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162ffec:a100::/24ffec:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163ffec:a200::/24ffec:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164ffec:a300::/24ffec:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165ffec:a400::/24ffec:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166ffec:a500::/24ffec:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167ffec:a600::/24ffec:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168ffec:a700::/24ffec:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169ffec:a800::/24ffec:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170ffec:a900::/24ffec:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171ffec:aa00::/24ffec:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172ffec:ab00::/24ffec:abff:ffff:ffff:ffff:ffff:ffff:ffff
173ffec:ac00::/24ffec:acff:ffff:ffff:ffff:ffff:ffff:ffff
174ffec:ad00::/24ffec:adff:ffff:ffff:ffff:ffff:ffff:ffff
175ffec:ae00::/24ffec:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176ffec:af00::/24ffec:afff:ffff:ffff:ffff:ffff:ffff:ffff
177ffec:b000::/24ffec:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178ffec:b100::/24ffec:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179ffec:b200::/24ffec:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180ffec:b300::/24ffec:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181ffec:b400::/24ffec:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182ffec:b500::/24ffec:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183ffec:b600::/24ffec:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184ffec:b700::/24ffec:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185ffec:b800::/24ffec:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186ffec:b900::/24ffec:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187ffec:ba00::/24ffec:baff:ffff:ffff:ffff:ffff:ffff:ffff
188ffec:bb00::/24ffec:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189ffec:bc00::/24ffec:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190ffec:bd00::/24ffec:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191ffec:be00::/24ffec:beff:ffff:ffff:ffff:ffff:ffff:ffff
192ffec:bf00::/24ffec:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193ffec:c000::/24ffec:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194ffec:c100::/24ffec:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195ffec:c200::/24ffec:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196ffec:c300::/24ffec:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197ffec:c400::/24ffec:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198ffec:c500::/24ffec:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199ffec:c600::/24ffec:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200ffec:c700::/24ffec:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201ffec:c800::/24ffec:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202ffec:c900::/24ffec:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203ffec:ca00::/24ffec:caff:ffff:ffff:ffff:ffff:ffff:ffff
204ffec:cb00::/24ffec:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205ffec:cc00::/24ffec:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206ffec:cd00::/24ffec:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207ffec:ce00::/24ffec:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208ffec:cf00::/24ffec:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209ffec:d000::/24ffec:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210ffec:d100::/24ffec:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211ffec:d200::/24ffec:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212ffec:d300::/24ffec:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213ffec:d400::/24ffec:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214ffec:d500::/24ffec:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215ffec:d600::/24ffec:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216ffec:d700::/24ffec:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217ffec:d800::/24ffec:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218ffec:d900::/24ffec:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219ffec:da00::/24ffec:daff:ffff:ffff:ffff:ffff:ffff:ffff
220ffec:db00::/24ffec:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221ffec:dc00::/24ffec:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222ffec:dd00::/24ffec:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223ffec:de00::/24ffec:deff:ffff:ffff:ffff:ffff:ffff:ffff
224ffec:df00::/24ffec:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225ffec:e000::/24ffec:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226ffec:e100::/24ffec:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227ffec:e200::/24ffec:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228ffec:e300::/24ffec:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229ffec:e400::/24ffec:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230ffec:e500::/24ffec:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231ffec:e600::/24ffec:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232ffec:e700::/24ffec:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233ffec:e800::/24ffec:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234ffec:e900::/24ffec:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235ffec:ea00::/24ffec:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236ffec:eb00::/24ffec:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237ffec:ec00::/24ffec:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238ffec:ed00::/24ffec:edff:ffff:ffff:ffff:ffff:ffff:ffff
239ffec:ee00::/24ffec:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240ffec:ef00::/24ffec:efff:ffff:ffff:ffff:ffff:ffff:ffff
241ffec:f000::/24ffec:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242ffec:f100::/24ffec:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243ffec:f200::/24ffec:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244ffec:f300::/24ffec:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245ffec:f400::/24ffec:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246ffec:f500::/24ffec:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247ffec:f600::/24ffec:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248ffec:f700::/24ffec:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249ffec:f800::/24ffec:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250ffec:f900::/24ffec:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251ffec:fa00::/24ffec:faff:ffff:ffff:ffff:ffff:ffff:ffff
252ffec:fb00::/24ffec:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253ffec:fc00::/24ffec:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254ffec:fd00::/24ffec:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255ffec:fe00::/24ffec:feff:ffff:ffff:ffff:ffff:ffff:ffff
256ffec:ff00::/24ffec:ffff:ffff:ffff:ffff:ffff:ffff:ffff

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.