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
fcda::/16
First address
fcda::
Last address
fcda: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
fcda:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
a.d.c.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

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

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