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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.

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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.

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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
fccf::/16
First address
fccf::
Last address
fccf: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
fccf:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
f.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)

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

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