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

fccc::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1fccc::/32fccc:0:ffff:ffff:ffff:ffff:ffff:ffff
2fccc:1::/32fccc:1:ffff:ffff:ffff:ffff:ffff:ffff
3fccc:2::/32fccc:2:ffff:ffff:ffff:ffff:ffff:ffff
4fccc:3::/32fccc:3:ffff:ffff:ffff:ffff:ffff:ffff
5fccc:4::/32fccc:4:ffff:ffff:ffff:ffff:ffff:ffff
6fccc:5::/32fccc:5:ffff:ffff:ffff:ffff:ffff:ffff
7fccc:6::/32fccc:6:ffff:ffff:ffff:ffff:ffff:ffff
8fccc:7::/32fccc:7:ffff:ffff:ffff:ffff:ffff:ffff
9fccc:8::/32fccc:8:ffff:ffff:ffff:ffff:ffff:ffff
10fccc:9::/32fccc:9:ffff:ffff:ffff:ffff:ffff:ffff
11fccc:a::/32fccc:a:ffff:ffff:ffff:ffff:ffff:ffff
12fccc:b::/32fccc:b:ffff:ffff:ffff:ffff:ffff:ffff
13fccc:c::/32fccc:c:ffff:ffff:ffff:ffff:ffff:ffff
14fccc:d::/32fccc:d:ffff:ffff:ffff:ffff:ffff:ffff
15fccc:e::/32fccc:e:ffff:ffff:ffff:ffff:ffff:ffff
16fccc:f::/32fccc:f:ffff:ffff:ffff:ffff:ffff:ffff
17fccc:10::/32fccc:10:ffff:ffff:ffff:ffff:ffff:ffff
18fccc:11::/32fccc:11:ffff:ffff:ffff:ffff:ffff:ffff
19fccc:12::/32fccc:12:ffff:ffff:ffff:ffff:ffff:ffff
20fccc:13::/32fccc:13:ffff:ffff:ffff:ffff:ffff:ffff
21fccc:14::/32fccc:14:ffff:ffff:ffff:ffff:ffff:ffff
22fccc:15::/32fccc:15:ffff:ffff:ffff:ffff:ffff:ffff
23fccc:16::/32fccc:16:ffff:ffff:ffff:ffff:ffff:ffff
24fccc:17::/32fccc:17:ffff:ffff:ffff:ffff:ffff:ffff
25fccc:18::/32fccc:18:ffff:ffff:ffff:ffff:ffff:ffff
26fccc:19::/32fccc:19:ffff:ffff:ffff:ffff:ffff:ffff
27fccc:1a::/32fccc:1a:ffff:ffff:ffff:ffff:ffff:ffff
28fccc:1b::/32fccc:1b:ffff:ffff:ffff:ffff:ffff:ffff
29fccc:1c::/32fccc:1c:ffff:ffff:ffff:ffff:ffff:ffff
30fccc:1d::/32fccc:1d:ffff:ffff:ffff:ffff:ffff:ffff
31fccc:1e::/32fccc:1e:ffff:ffff:ffff:ffff:ffff:ffff
32fccc:1f::/32fccc:1f:ffff:ffff:ffff:ffff:ffff:ffff
33fccc:20::/32fccc:20:ffff:ffff:ffff:ffff:ffff:ffff
34fccc:21::/32fccc:21:ffff:ffff:ffff:ffff:ffff:ffff
35fccc:22::/32fccc:22:ffff:ffff:ffff:ffff:ffff:ffff
36fccc:23::/32fccc:23:ffff:ffff:ffff:ffff:ffff:ffff
37fccc:24::/32fccc:24:ffff:ffff:ffff:ffff:ffff:ffff
38fccc:25::/32fccc:25:ffff:ffff:ffff:ffff:ffff:ffff
39fccc:26::/32fccc:26:ffff:ffff:ffff:ffff:ffff:ffff
40fccc:27::/32fccc:27:ffff:ffff:ffff:ffff:ffff:ffff
41fccc:28::/32fccc:28:ffff:ffff:ffff:ffff:ffff:ffff
42fccc:29::/32fccc:29:ffff:ffff:ffff:ffff:ffff:ffff
43fccc:2a::/32fccc:2a:ffff:ffff:ffff:ffff:ffff:ffff
44fccc:2b::/32fccc:2b:ffff:ffff:ffff:ffff:ffff:ffff
45fccc:2c::/32fccc:2c:ffff:ffff:ffff:ffff:ffff:ffff
46fccc:2d::/32fccc:2d:ffff:ffff:ffff:ffff:ffff:ffff
47fccc:2e::/32fccc:2e:ffff:ffff:ffff:ffff:ffff:ffff
48fccc:2f::/32fccc:2f:ffff:ffff:ffff:ffff:ffff:ffff
49fccc:30::/32fccc:30:ffff:ffff:ffff:ffff:ffff:ffff
50fccc:31::/32fccc:31:ffff:ffff:ffff:ffff:ffff:ffff
51fccc:32::/32fccc:32:ffff:ffff:ffff:ffff:ffff:ffff
52fccc:33::/32fccc:33:ffff:ffff:ffff:ffff:ffff:ffff
53fccc:34::/32fccc:34:ffff:ffff:ffff:ffff:ffff:ffff
54fccc:35::/32fccc:35:ffff:ffff:ffff:ffff:ffff:ffff
55fccc:36::/32fccc:36:ffff:ffff:ffff:ffff:ffff:ffff
56fccc:37::/32fccc:37:ffff:ffff:ffff:ffff:ffff:ffff
57fccc:38::/32fccc:38:ffff:ffff:ffff:ffff:ffff:ffff
58fccc:39::/32fccc:39:ffff:ffff:ffff:ffff:ffff:ffff
59fccc:3a::/32fccc:3a:ffff:ffff:ffff:ffff:ffff:ffff
60fccc:3b::/32fccc:3b:ffff:ffff:ffff:ffff:ffff:ffff
61fccc:3c::/32fccc:3c:ffff:ffff:ffff:ffff:ffff:ffff
62fccc:3d::/32fccc:3d:ffff:ffff:ffff:ffff:ffff:ffff
63fccc:3e::/32fccc:3e:ffff:ffff:ffff:ffff:ffff:ffff
64fccc:3f::/32fccc:3f:ffff:ffff:ffff:ffff:ffff:ffff
65fccc:40::/32fccc:40:ffff:ffff:ffff:ffff:ffff:ffff
66fccc:41::/32fccc:41:ffff:ffff:ffff:ffff:ffff:ffff
67fccc:42::/32fccc:42:ffff:ffff:ffff:ffff:ffff:ffff
68fccc:43::/32fccc:43:ffff:ffff:ffff:ffff:ffff:ffff
69fccc:44::/32fccc:44:ffff:ffff:ffff:ffff:ffff:ffff
70fccc:45::/32fccc:45:ffff:ffff:ffff:ffff:ffff:ffff
71fccc:46::/32fccc:46:ffff:ffff:ffff:ffff:ffff:ffff
72fccc:47::/32fccc:47:ffff:ffff:ffff:ffff:ffff:ffff
73fccc:48::/32fccc:48:ffff:ffff:ffff:ffff:ffff:ffff
74fccc:49::/32fccc:49:ffff:ffff:ffff:ffff:ffff:ffff
75fccc:4a::/32fccc:4a:ffff:ffff:ffff:ffff:ffff:ffff
76fccc:4b::/32fccc:4b:ffff:ffff:ffff:ffff:ffff:ffff
77fccc:4c::/32fccc:4c:ffff:ffff:ffff:ffff:ffff:ffff
78fccc:4d::/32fccc:4d:ffff:ffff:ffff:ffff:ffff:ffff
79fccc:4e::/32fccc:4e:ffff:ffff:ffff:ffff:ffff:ffff
80fccc:4f::/32fccc:4f:ffff:ffff:ffff:ffff:ffff:ffff
81fccc:50::/32fccc:50:ffff:ffff:ffff:ffff:ffff:ffff
82fccc:51::/32fccc:51:ffff:ffff:ffff:ffff:ffff:ffff
83fccc:52::/32fccc:52:ffff:ffff:ffff:ffff:ffff:ffff
84fccc:53::/32fccc:53:ffff:ffff:ffff:ffff:ffff:ffff
85fccc:54::/32fccc:54:ffff:ffff:ffff:ffff:ffff:ffff
86fccc:55::/32fccc:55:ffff:ffff:ffff:ffff:ffff:ffff
87fccc:56::/32fccc:56:ffff:ffff:ffff:ffff:ffff:ffff
88fccc:57::/32fccc:57:ffff:ffff:ffff:ffff:ffff:ffff
89fccc:58::/32fccc:58:ffff:ffff:ffff:ffff:ffff:ffff
90fccc:59::/32fccc:59:ffff:ffff:ffff:ffff:ffff:ffff
91fccc:5a::/32fccc:5a:ffff:ffff:ffff:ffff:ffff:ffff
92fccc:5b::/32fccc:5b:ffff:ffff:ffff:ffff:ffff:ffff
93fccc:5c::/32fccc:5c:ffff:ffff:ffff:ffff:ffff:ffff
94fccc:5d::/32fccc:5d:ffff:ffff:ffff:ffff:ffff:ffff
95fccc:5e::/32fccc:5e:ffff:ffff:ffff:ffff:ffff:ffff
96fccc:5f::/32fccc:5f:ffff:ffff:ffff:ffff:ffff:ffff
97fccc:60::/32fccc:60:ffff:ffff:ffff:ffff:ffff:ffff
98fccc:61::/32fccc:61:ffff:ffff:ffff:ffff:ffff:ffff
99fccc:62::/32fccc:62:ffff:ffff:ffff:ffff:ffff:ffff
100fccc:63::/32fccc:63:ffff:ffff:ffff:ffff:ffff:ffff
101fccc:64::/32fccc:64:ffff:ffff:ffff:ffff:ffff:ffff
102fccc:65::/32fccc:65:ffff:ffff:ffff:ffff:ffff:ffff
103fccc:66::/32fccc:66:ffff:ffff:ffff:ffff:ffff:ffff
104fccc:67::/32fccc:67:ffff:ffff:ffff:ffff:ffff:ffff
105fccc:68::/32fccc:68:ffff:ffff:ffff:ffff:ffff:ffff
106fccc:69::/32fccc:69:ffff:ffff:ffff:ffff:ffff:ffff
107fccc:6a::/32fccc:6a:ffff:ffff:ffff:ffff:ffff:ffff
108fccc:6b::/32fccc:6b:ffff:ffff:ffff:ffff:ffff:ffff
109fccc:6c::/32fccc:6c:ffff:ffff:ffff:ffff:ffff:ffff
110fccc:6d::/32fccc:6d:ffff:ffff:ffff:ffff:ffff:ffff
111fccc:6e::/32fccc:6e:ffff:ffff:ffff:ffff:ffff:ffff
112fccc:6f::/32fccc:6f:ffff:ffff:ffff:ffff:ffff:ffff
113fccc:70::/32fccc:70:ffff:ffff:ffff:ffff:ffff:ffff
114fccc:71::/32fccc:71:ffff:ffff:ffff:ffff:ffff:ffff
115fccc:72::/32fccc:72:ffff:ffff:ffff:ffff:ffff:ffff
116fccc:73::/32fccc:73:ffff:ffff:ffff:ffff:ffff:ffff
117fccc:74::/32fccc:74:ffff:ffff:ffff:ffff:ffff:ffff
118fccc:75::/32fccc:75:ffff:ffff:ffff:ffff:ffff:ffff
119fccc:76::/32fccc:76:ffff:ffff:ffff:ffff:ffff:ffff
120fccc:77::/32fccc:77:ffff:ffff:ffff:ffff:ffff:ffff
121fccc:78::/32fccc:78:ffff:ffff:ffff:ffff:ffff:ffff
122fccc:79::/32fccc:79:ffff:ffff:ffff:ffff:ffff:ffff
123fccc:7a::/32fccc:7a:ffff:ffff:ffff:ffff:ffff:ffff
124fccc:7b::/32fccc:7b:ffff:ffff:ffff:ffff:ffff:ffff
125fccc:7c::/32fccc:7c:ffff:ffff:ffff:ffff:ffff:ffff
126fccc:7d::/32fccc:7d:ffff:ffff:ffff:ffff:ffff:ffff
127fccc:7e::/32fccc:7e:ffff:ffff:ffff:ffff:ffff:ffff
128fccc:7f::/32fccc:7f:ffff:ffff:ffff:ffff:ffff:ffff
129fccc:80::/32fccc:80:ffff:ffff:ffff:ffff:ffff:ffff
130fccc:81::/32fccc:81:ffff:ffff:ffff:ffff:ffff:ffff
131fccc:82::/32fccc:82:ffff:ffff:ffff:ffff:ffff:ffff
132fccc:83::/32fccc:83:ffff:ffff:ffff:ffff:ffff:ffff
133fccc:84::/32fccc:84:ffff:ffff:ffff:ffff:ffff:ffff
134fccc:85::/32fccc:85:ffff:ffff:ffff:ffff:ffff:ffff
135fccc:86::/32fccc:86:ffff:ffff:ffff:ffff:ffff:ffff
136fccc:87::/32fccc:87:ffff:ffff:ffff:ffff:ffff:ffff
137fccc:88::/32fccc:88:ffff:ffff:ffff:ffff:ffff:ffff
138fccc:89::/32fccc:89:ffff:ffff:ffff:ffff:ffff:ffff
139fccc:8a::/32fccc:8a:ffff:ffff:ffff:ffff:ffff:ffff
140fccc:8b::/32fccc:8b:ffff:ffff:ffff:ffff:ffff:ffff
141fccc:8c::/32fccc:8c:ffff:ffff:ffff:ffff:ffff:ffff
142fccc:8d::/32fccc:8d:ffff:ffff:ffff:ffff:ffff:ffff
143fccc:8e::/32fccc:8e:ffff:ffff:ffff:ffff:ffff:ffff
144fccc:8f::/32fccc:8f:ffff:ffff:ffff:ffff:ffff:ffff
145fccc:90::/32fccc:90:ffff:ffff:ffff:ffff:ffff:ffff
146fccc:91::/32fccc:91:ffff:ffff:ffff:ffff:ffff:ffff
147fccc:92::/32fccc:92:ffff:ffff:ffff:ffff:ffff:ffff
148fccc:93::/32fccc:93:ffff:ffff:ffff:ffff:ffff:ffff
149fccc:94::/32fccc:94:ffff:ffff:ffff:ffff:ffff:ffff
150fccc:95::/32fccc:95:ffff:ffff:ffff:ffff:ffff:ffff
151fccc:96::/32fccc:96:ffff:ffff:ffff:ffff:ffff:ffff
152fccc:97::/32fccc:97:ffff:ffff:ffff:ffff:ffff:ffff
153fccc:98::/32fccc:98:ffff:ffff:ffff:ffff:ffff:ffff
154fccc:99::/32fccc:99:ffff:ffff:ffff:ffff:ffff:ffff
155fccc:9a::/32fccc:9a:ffff:ffff:ffff:ffff:ffff:ffff
156fccc:9b::/32fccc:9b:ffff:ffff:ffff:ffff:ffff:ffff
157fccc:9c::/32fccc:9c:ffff:ffff:ffff:ffff:ffff:ffff
158fccc:9d::/32fccc:9d:ffff:ffff:ffff:ffff:ffff:ffff
159fccc:9e::/32fccc:9e:ffff:ffff:ffff:ffff:ffff:ffff
160fccc:9f::/32fccc:9f:ffff:ffff:ffff:ffff:ffff:ffff
161fccc:a0::/32fccc:a0:ffff:ffff:ffff:ffff:ffff:ffff
162fccc:a1::/32fccc:a1:ffff:ffff:ffff:ffff:ffff:ffff
163fccc:a2::/32fccc:a2:ffff:ffff:ffff:ffff:ffff:ffff
164fccc:a3::/32fccc:a3:ffff:ffff:ffff:ffff:ffff:ffff
165fccc:a4::/32fccc:a4:ffff:ffff:ffff:ffff:ffff:ffff
166fccc:a5::/32fccc:a5:ffff:ffff:ffff:ffff:ffff:ffff
167fccc:a6::/32fccc:a6:ffff:ffff:ffff:ffff:ffff:ffff
168fccc:a7::/32fccc:a7:ffff:ffff:ffff:ffff:ffff:ffff
169fccc:a8::/32fccc:a8:ffff:ffff:ffff:ffff:ffff:ffff
170fccc:a9::/32fccc:a9:ffff:ffff:ffff:ffff:ffff:ffff
171fccc:aa::/32fccc:aa:ffff:ffff:ffff:ffff:ffff:ffff
172fccc:ab::/32fccc:ab:ffff:ffff:ffff:ffff:ffff:ffff
173fccc:ac::/32fccc:ac:ffff:ffff:ffff:ffff:ffff:ffff
174fccc:ad::/32fccc:ad:ffff:ffff:ffff:ffff:ffff:ffff
175fccc:ae::/32fccc:ae:ffff:ffff:ffff:ffff:ffff:ffff
176fccc:af::/32fccc:af:ffff:ffff:ffff:ffff:ffff:ffff
177fccc:b0::/32fccc:b0:ffff:ffff:ffff:ffff:ffff:ffff
178fccc:b1::/32fccc:b1:ffff:ffff:ffff:ffff:ffff:ffff
179fccc:b2::/32fccc:b2:ffff:ffff:ffff:ffff:ffff:ffff
180fccc:b3::/32fccc:b3:ffff:ffff:ffff:ffff:ffff:ffff
181fccc:b4::/32fccc:b4:ffff:ffff:ffff:ffff:ffff:ffff
182fccc:b5::/32fccc:b5:ffff:ffff:ffff:ffff:ffff:ffff
183fccc:b6::/32fccc:b6:ffff:ffff:ffff:ffff:ffff:ffff
184fccc:b7::/32fccc:b7:ffff:ffff:ffff:ffff:ffff:ffff
185fccc:b8::/32fccc:b8:ffff:ffff:ffff:ffff:ffff:ffff
186fccc:b9::/32fccc:b9:ffff:ffff:ffff:ffff:ffff:ffff
187fccc:ba::/32fccc:ba:ffff:ffff:ffff:ffff:ffff:ffff
188fccc:bb::/32fccc:bb:ffff:ffff:ffff:ffff:ffff:ffff
189fccc:bc::/32fccc:bc:ffff:ffff:ffff:ffff:ffff:ffff
190fccc:bd::/32fccc:bd:ffff:ffff:ffff:ffff:ffff:ffff
191fccc:be::/32fccc:be:ffff:ffff:ffff:ffff:ffff:ffff
192fccc:bf::/32fccc:bf:ffff:ffff:ffff:ffff:ffff:ffff
193fccc:c0::/32fccc:c0:ffff:ffff:ffff:ffff:ffff:ffff
194fccc:c1::/32fccc:c1:ffff:ffff:ffff:ffff:ffff:ffff
195fccc:c2::/32fccc:c2:ffff:ffff:ffff:ffff:ffff:ffff
196fccc:c3::/32fccc:c3:ffff:ffff:ffff:ffff:ffff:ffff
197fccc:c4::/32fccc:c4:ffff:ffff:ffff:ffff:ffff:ffff
198fccc:c5::/32fccc:c5:ffff:ffff:ffff:ffff:ffff:ffff
199fccc:c6::/32fccc:c6:ffff:ffff:ffff:ffff:ffff:ffff
200fccc:c7::/32fccc:c7:ffff:ffff:ffff:ffff:ffff:ffff
201fccc:c8::/32fccc:c8:ffff:ffff:ffff:ffff:ffff:ffff
202fccc:c9::/32fccc:c9:ffff:ffff:ffff:ffff:ffff:ffff
203fccc:ca::/32fccc:ca:ffff:ffff:ffff:ffff:ffff:ffff
204fccc:cb::/32fccc:cb:ffff:ffff:ffff:ffff:ffff:ffff
205fccc:cc::/32fccc:cc:ffff:ffff:ffff:ffff:ffff:ffff
206fccc:cd::/32fccc:cd:ffff:ffff:ffff:ffff:ffff:ffff
207fccc:ce::/32fccc:ce:ffff:ffff:ffff:ffff:ffff:ffff
208fccc:cf::/32fccc:cf:ffff:ffff:ffff:ffff:ffff:ffff
209fccc:d0::/32fccc:d0:ffff:ffff:ffff:ffff:ffff:ffff
210fccc:d1::/32fccc:d1:ffff:ffff:ffff:ffff:ffff:ffff
211fccc:d2::/32fccc:d2:ffff:ffff:ffff:ffff:ffff:ffff
212fccc:d3::/32fccc:d3:ffff:ffff:ffff:ffff:ffff:ffff
213fccc:d4::/32fccc:d4:ffff:ffff:ffff:ffff:ffff:ffff
214fccc:d5::/32fccc:d5:ffff:ffff:ffff:ffff:ffff:ffff
215fccc:d6::/32fccc:d6:ffff:ffff:ffff:ffff:ffff:ffff
216fccc:d7::/32fccc:d7:ffff:ffff:ffff:ffff:ffff:ffff
217fccc:d8::/32fccc:d8:ffff:ffff:ffff:ffff:ffff:ffff
218fccc:d9::/32fccc:d9:ffff:ffff:ffff:ffff:ffff:ffff
219fccc:da::/32fccc:da:ffff:ffff:ffff:ffff:ffff:ffff
220fccc:db::/32fccc:db:ffff:ffff:ffff:ffff:ffff:ffff
221fccc:dc::/32fccc:dc:ffff:ffff:ffff:ffff:ffff:ffff
222fccc:dd::/32fccc:dd:ffff:ffff:ffff:ffff:ffff:ffff
223fccc:de::/32fccc:de:ffff:ffff:ffff:ffff:ffff:ffff
224fccc:df::/32fccc:df:ffff:ffff:ffff:ffff:ffff:ffff
225fccc:e0::/32fccc:e0:ffff:ffff:ffff:ffff:ffff:ffff
226fccc:e1::/32fccc:e1:ffff:ffff:ffff:ffff:ffff:ffff
227fccc:e2::/32fccc:e2:ffff:ffff:ffff:ffff:ffff:ffff
228fccc:e3::/32fccc:e3:ffff:ffff:ffff:ffff:ffff:ffff
229fccc:e4::/32fccc:e4:ffff:ffff:ffff:ffff:ffff:ffff
230fccc:e5::/32fccc:e5:ffff:ffff:ffff:ffff:ffff:ffff
231fccc:e6::/32fccc:e6:ffff:ffff:ffff:ffff:ffff:ffff
232fccc:e7::/32fccc:e7:ffff:ffff:ffff:ffff:ffff:ffff
233fccc:e8::/32fccc:e8:ffff:ffff:ffff:ffff:ffff:ffff
234fccc:e9::/32fccc:e9:ffff:ffff:ffff:ffff:ffff:ffff
235fccc:ea::/32fccc:ea:ffff:ffff:ffff:ffff:ffff:ffff
236fccc:eb::/32fccc:eb:ffff:ffff:ffff:ffff:ffff:ffff
237fccc:ec::/32fccc:ec:ffff:ffff:ffff:ffff:ffff:ffff
238fccc:ed::/32fccc:ed:ffff:ffff:ffff:ffff:ffff:ffff
239fccc:ee::/32fccc:ee:ffff:ffff:ffff:ffff:ffff:ffff
240fccc:ef::/32fccc:ef:ffff:ffff:ffff:ffff:ffff:ffff
241fccc:f0::/32fccc:f0:ffff:ffff:ffff:ffff:ffff:ffff
242fccc:f1::/32fccc:f1:ffff:ffff:ffff:ffff:ffff:ffff
243fccc:f2::/32fccc:f2:ffff:ffff:ffff:ffff:ffff:ffff
244fccc:f3::/32fccc:f3:ffff:ffff:ffff:ffff:ffff:ffff
245fccc:f4::/32fccc:f4:ffff:ffff:ffff:ffff:ffff:ffff
246fccc:f5::/32fccc:f5:ffff:ffff:ffff:ffff:ffff:ffff
247fccc:f6::/32fccc:f6:ffff:ffff:ffff:ffff:ffff:ffff
248fccc:f7::/32fccc:f7:ffff:ffff:ffff:ffff:ffff:ffff
249fccc:f8::/32fccc:f8:ffff:ffff:ffff:ffff:ffff:ffff
250fccc:f9::/32fccc:f9:ffff:ffff:ffff:ffff:ffff:ffff
251fccc:fa::/32fccc:fa:ffff:ffff:ffff:ffff:ffff:ffff
252fccc:fb::/32fccc:fb:ffff:ffff:ffff:ffff:ffff:ffff
253fccc:fc::/32fccc:fc:ffff:ffff:ffff:ffff:ffff:ffff
254fccc:fd::/32fccc:fd:ffff:ffff:ffff:ffff:ffff:ffff
255fccc:fe::/32fccc:fe:ffff:ffff:ffff:ffff:ffff:ffff
256fccc:ff::/32fccc:ff: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.