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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
ff2d::/16
First address
ff2d::
Last address
ff2d: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
ff2d:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
d.2.f.f.ip6.arpa
Split into smaller subnets/32
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ff2d::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1ff2d::/32ff2d:0:ffff:ffff:ffff:ffff:ffff:ffff
2ff2d:1::/32ff2d:1:ffff:ffff:ffff:ffff:ffff:ffff
3ff2d:2::/32ff2d:2:ffff:ffff:ffff:ffff:ffff:ffff
4ff2d:3::/32ff2d:3:ffff:ffff:ffff:ffff:ffff:ffff
5ff2d:4::/32ff2d:4:ffff:ffff:ffff:ffff:ffff:ffff
6ff2d:5::/32ff2d:5:ffff:ffff:ffff:ffff:ffff:ffff
7ff2d:6::/32ff2d:6:ffff:ffff:ffff:ffff:ffff:ffff
8ff2d:7::/32ff2d:7:ffff:ffff:ffff:ffff:ffff:ffff
9ff2d:8::/32ff2d:8:ffff:ffff:ffff:ffff:ffff:ffff
10ff2d:9::/32ff2d:9:ffff:ffff:ffff:ffff:ffff:ffff
11ff2d:a::/32ff2d:a:ffff:ffff:ffff:ffff:ffff:ffff
12ff2d:b::/32ff2d:b:ffff:ffff:ffff:ffff:ffff:ffff
13ff2d:c::/32ff2d:c:ffff:ffff:ffff:ffff:ffff:ffff
14ff2d:d::/32ff2d:d:ffff:ffff:ffff:ffff:ffff:ffff
15ff2d:e::/32ff2d:e:ffff:ffff:ffff:ffff:ffff:ffff
16ff2d:f::/32ff2d:f:ffff:ffff:ffff:ffff:ffff:ffff
17ff2d:10::/32ff2d:10:ffff:ffff:ffff:ffff:ffff:ffff
18ff2d:11::/32ff2d:11:ffff:ffff:ffff:ffff:ffff:ffff
19ff2d:12::/32ff2d:12:ffff:ffff:ffff:ffff:ffff:ffff
20ff2d:13::/32ff2d:13:ffff:ffff:ffff:ffff:ffff:ffff
21ff2d:14::/32ff2d:14:ffff:ffff:ffff:ffff:ffff:ffff
22ff2d:15::/32ff2d:15:ffff:ffff:ffff:ffff:ffff:ffff
23ff2d:16::/32ff2d:16:ffff:ffff:ffff:ffff:ffff:ffff
24ff2d:17::/32ff2d:17:ffff:ffff:ffff:ffff:ffff:ffff
25ff2d:18::/32ff2d:18:ffff:ffff:ffff:ffff:ffff:ffff
26ff2d:19::/32ff2d:19:ffff:ffff:ffff:ffff:ffff:ffff
27ff2d:1a::/32ff2d:1a:ffff:ffff:ffff:ffff:ffff:ffff
28ff2d:1b::/32ff2d:1b:ffff:ffff:ffff:ffff:ffff:ffff
29ff2d:1c::/32ff2d:1c:ffff:ffff:ffff:ffff:ffff:ffff
30ff2d:1d::/32ff2d:1d:ffff:ffff:ffff:ffff:ffff:ffff
31ff2d:1e::/32ff2d:1e:ffff:ffff:ffff:ffff:ffff:ffff
32ff2d:1f::/32ff2d:1f:ffff:ffff:ffff:ffff:ffff:ffff
33ff2d:20::/32ff2d:20:ffff:ffff:ffff:ffff:ffff:ffff
34ff2d:21::/32ff2d:21:ffff:ffff:ffff:ffff:ffff:ffff
35ff2d:22::/32ff2d:22:ffff:ffff:ffff:ffff:ffff:ffff
36ff2d:23::/32ff2d:23:ffff:ffff:ffff:ffff:ffff:ffff
37ff2d:24::/32ff2d:24:ffff:ffff:ffff:ffff:ffff:ffff
38ff2d:25::/32ff2d:25:ffff:ffff:ffff:ffff:ffff:ffff
39ff2d:26::/32ff2d:26:ffff:ffff:ffff:ffff:ffff:ffff
40ff2d:27::/32ff2d:27:ffff:ffff:ffff:ffff:ffff:ffff
41ff2d:28::/32ff2d:28:ffff:ffff:ffff:ffff:ffff:ffff
42ff2d:29::/32ff2d:29:ffff:ffff:ffff:ffff:ffff:ffff
43ff2d:2a::/32ff2d:2a:ffff:ffff:ffff:ffff:ffff:ffff
44ff2d:2b::/32ff2d:2b:ffff:ffff:ffff:ffff:ffff:ffff
45ff2d:2c::/32ff2d:2c:ffff:ffff:ffff:ffff:ffff:ffff
46ff2d:2d::/32ff2d:2d:ffff:ffff:ffff:ffff:ffff:ffff
47ff2d:2e::/32ff2d:2e:ffff:ffff:ffff:ffff:ffff:ffff
48ff2d:2f::/32ff2d:2f:ffff:ffff:ffff:ffff:ffff:ffff
49ff2d:30::/32ff2d:30:ffff:ffff:ffff:ffff:ffff:ffff
50ff2d:31::/32ff2d:31:ffff:ffff:ffff:ffff:ffff:ffff
51ff2d:32::/32ff2d:32:ffff:ffff:ffff:ffff:ffff:ffff
52ff2d:33::/32ff2d:33:ffff:ffff:ffff:ffff:ffff:ffff
53ff2d:34::/32ff2d:34:ffff:ffff:ffff:ffff:ffff:ffff
54ff2d:35::/32ff2d:35:ffff:ffff:ffff:ffff:ffff:ffff
55ff2d:36::/32ff2d:36:ffff:ffff:ffff:ffff:ffff:ffff
56ff2d:37::/32ff2d:37:ffff:ffff:ffff:ffff:ffff:ffff
57ff2d:38::/32ff2d:38:ffff:ffff:ffff:ffff:ffff:ffff
58ff2d:39::/32ff2d:39:ffff:ffff:ffff:ffff:ffff:ffff
59ff2d:3a::/32ff2d:3a:ffff:ffff:ffff:ffff:ffff:ffff
60ff2d:3b::/32ff2d:3b:ffff:ffff:ffff:ffff:ffff:ffff
61ff2d:3c::/32ff2d:3c:ffff:ffff:ffff:ffff:ffff:ffff
62ff2d:3d::/32ff2d:3d:ffff:ffff:ffff:ffff:ffff:ffff
63ff2d:3e::/32ff2d:3e:ffff:ffff:ffff:ffff:ffff:ffff
64ff2d:3f::/32ff2d:3f:ffff:ffff:ffff:ffff:ffff:ffff
65ff2d:40::/32ff2d:40:ffff:ffff:ffff:ffff:ffff:ffff
66ff2d:41::/32ff2d:41:ffff:ffff:ffff:ffff:ffff:ffff
67ff2d:42::/32ff2d:42:ffff:ffff:ffff:ffff:ffff:ffff
68ff2d:43::/32ff2d:43:ffff:ffff:ffff:ffff:ffff:ffff
69ff2d:44::/32ff2d:44:ffff:ffff:ffff:ffff:ffff:ffff
70ff2d:45::/32ff2d:45:ffff:ffff:ffff:ffff:ffff:ffff
71ff2d:46::/32ff2d:46:ffff:ffff:ffff:ffff:ffff:ffff
72ff2d:47::/32ff2d:47:ffff:ffff:ffff:ffff:ffff:ffff
73ff2d:48::/32ff2d:48:ffff:ffff:ffff:ffff:ffff:ffff
74ff2d:49::/32ff2d:49:ffff:ffff:ffff:ffff:ffff:ffff
75ff2d:4a::/32ff2d:4a:ffff:ffff:ffff:ffff:ffff:ffff
76ff2d:4b::/32ff2d:4b:ffff:ffff:ffff:ffff:ffff:ffff
77ff2d:4c::/32ff2d:4c:ffff:ffff:ffff:ffff:ffff:ffff
78ff2d:4d::/32ff2d:4d:ffff:ffff:ffff:ffff:ffff:ffff
79ff2d:4e::/32ff2d:4e:ffff:ffff:ffff:ffff:ffff:ffff
80ff2d:4f::/32ff2d:4f:ffff:ffff:ffff:ffff:ffff:ffff
81ff2d:50::/32ff2d:50:ffff:ffff:ffff:ffff:ffff:ffff
82ff2d:51::/32ff2d:51:ffff:ffff:ffff:ffff:ffff:ffff
83ff2d:52::/32ff2d:52:ffff:ffff:ffff:ffff:ffff:ffff
84ff2d:53::/32ff2d:53:ffff:ffff:ffff:ffff:ffff:ffff
85ff2d:54::/32ff2d:54:ffff:ffff:ffff:ffff:ffff:ffff
86ff2d:55::/32ff2d:55:ffff:ffff:ffff:ffff:ffff:ffff
87ff2d:56::/32ff2d:56:ffff:ffff:ffff:ffff:ffff:ffff
88ff2d:57::/32ff2d:57:ffff:ffff:ffff:ffff:ffff:ffff
89ff2d:58::/32ff2d:58:ffff:ffff:ffff:ffff:ffff:ffff
90ff2d:59::/32ff2d:59:ffff:ffff:ffff:ffff:ffff:ffff
91ff2d:5a::/32ff2d:5a:ffff:ffff:ffff:ffff:ffff:ffff
92ff2d:5b::/32ff2d:5b:ffff:ffff:ffff:ffff:ffff:ffff
93ff2d:5c::/32ff2d:5c:ffff:ffff:ffff:ffff:ffff:ffff
94ff2d:5d::/32ff2d:5d:ffff:ffff:ffff:ffff:ffff:ffff
95ff2d:5e::/32ff2d:5e:ffff:ffff:ffff:ffff:ffff:ffff
96ff2d:5f::/32ff2d:5f:ffff:ffff:ffff:ffff:ffff:ffff
97ff2d:60::/32ff2d:60:ffff:ffff:ffff:ffff:ffff:ffff
98ff2d:61::/32ff2d:61:ffff:ffff:ffff:ffff:ffff:ffff
99ff2d:62::/32ff2d:62:ffff:ffff:ffff:ffff:ffff:ffff
100ff2d:63::/32ff2d:63:ffff:ffff:ffff:ffff:ffff:ffff
101ff2d:64::/32ff2d:64:ffff:ffff:ffff:ffff:ffff:ffff
102ff2d:65::/32ff2d:65:ffff:ffff:ffff:ffff:ffff:ffff
103ff2d:66::/32ff2d:66:ffff:ffff:ffff:ffff:ffff:ffff
104ff2d:67::/32ff2d:67:ffff:ffff:ffff:ffff:ffff:ffff
105ff2d:68::/32ff2d:68:ffff:ffff:ffff:ffff:ffff:ffff
106ff2d:69::/32ff2d:69:ffff:ffff:ffff:ffff:ffff:ffff
107ff2d:6a::/32ff2d:6a:ffff:ffff:ffff:ffff:ffff:ffff
108ff2d:6b::/32ff2d:6b:ffff:ffff:ffff:ffff:ffff:ffff
109ff2d:6c::/32ff2d:6c:ffff:ffff:ffff:ffff:ffff:ffff
110ff2d:6d::/32ff2d:6d:ffff:ffff:ffff:ffff:ffff:ffff
111ff2d:6e::/32ff2d:6e:ffff:ffff:ffff:ffff:ffff:ffff
112ff2d:6f::/32ff2d:6f:ffff:ffff:ffff:ffff:ffff:ffff
113ff2d:70::/32ff2d:70:ffff:ffff:ffff:ffff:ffff:ffff
114ff2d:71::/32ff2d:71:ffff:ffff:ffff:ffff:ffff:ffff
115ff2d:72::/32ff2d:72:ffff:ffff:ffff:ffff:ffff:ffff
116ff2d:73::/32ff2d:73:ffff:ffff:ffff:ffff:ffff:ffff
117ff2d:74::/32ff2d:74:ffff:ffff:ffff:ffff:ffff:ffff
118ff2d:75::/32ff2d:75:ffff:ffff:ffff:ffff:ffff:ffff
119ff2d:76::/32ff2d:76:ffff:ffff:ffff:ffff:ffff:ffff
120ff2d:77::/32ff2d:77:ffff:ffff:ffff:ffff:ffff:ffff
121ff2d:78::/32ff2d:78:ffff:ffff:ffff:ffff:ffff:ffff
122ff2d:79::/32ff2d:79:ffff:ffff:ffff:ffff:ffff:ffff
123ff2d:7a::/32ff2d:7a:ffff:ffff:ffff:ffff:ffff:ffff
124ff2d:7b::/32ff2d:7b:ffff:ffff:ffff:ffff:ffff:ffff
125ff2d:7c::/32ff2d:7c:ffff:ffff:ffff:ffff:ffff:ffff
126ff2d:7d::/32ff2d:7d:ffff:ffff:ffff:ffff:ffff:ffff
127ff2d:7e::/32ff2d:7e:ffff:ffff:ffff:ffff:ffff:ffff
128ff2d:7f::/32ff2d:7f:ffff:ffff:ffff:ffff:ffff:ffff
129ff2d:80::/32ff2d:80:ffff:ffff:ffff:ffff:ffff:ffff
130ff2d:81::/32ff2d:81:ffff:ffff:ffff:ffff:ffff:ffff
131ff2d:82::/32ff2d:82:ffff:ffff:ffff:ffff:ffff:ffff
132ff2d:83::/32ff2d:83:ffff:ffff:ffff:ffff:ffff:ffff
133ff2d:84::/32ff2d:84:ffff:ffff:ffff:ffff:ffff:ffff
134ff2d:85::/32ff2d:85:ffff:ffff:ffff:ffff:ffff:ffff
135ff2d:86::/32ff2d:86:ffff:ffff:ffff:ffff:ffff:ffff
136ff2d:87::/32ff2d:87:ffff:ffff:ffff:ffff:ffff:ffff
137ff2d:88::/32ff2d:88:ffff:ffff:ffff:ffff:ffff:ffff
138ff2d:89::/32ff2d:89:ffff:ffff:ffff:ffff:ffff:ffff
139ff2d:8a::/32ff2d:8a:ffff:ffff:ffff:ffff:ffff:ffff
140ff2d:8b::/32ff2d:8b:ffff:ffff:ffff:ffff:ffff:ffff
141ff2d:8c::/32ff2d:8c:ffff:ffff:ffff:ffff:ffff:ffff
142ff2d:8d::/32ff2d:8d:ffff:ffff:ffff:ffff:ffff:ffff
143ff2d:8e::/32ff2d:8e:ffff:ffff:ffff:ffff:ffff:ffff
144ff2d:8f::/32ff2d:8f:ffff:ffff:ffff:ffff:ffff:ffff
145ff2d:90::/32ff2d:90:ffff:ffff:ffff:ffff:ffff:ffff
146ff2d:91::/32ff2d:91:ffff:ffff:ffff:ffff:ffff:ffff
147ff2d:92::/32ff2d:92:ffff:ffff:ffff:ffff:ffff:ffff
148ff2d:93::/32ff2d:93:ffff:ffff:ffff:ffff:ffff:ffff
149ff2d:94::/32ff2d:94:ffff:ffff:ffff:ffff:ffff:ffff
150ff2d:95::/32ff2d:95:ffff:ffff:ffff:ffff:ffff:ffff
151ff2d:96::/32ff2d:96:ffff:ffff:ffff:ffff:ffff:ffff
152ff2d:97::/32ff2d:97:ffff:ffff:ffff:ffff:ffff:ffff
153ff2d:98::/32ff2d:98:ffff:ffff:ffff:ffff:ffff:ffff
154ff2d:99::/32ff2d:99:ffff:ffff:ffff:ffff:ffff:ffff
155ff2d:9a::/32ff2d:9a:ffff:ffff:ffff:ffff:ffff:ffff
156ff2d:9b::/32ff2d:9b:ffff:ffff:ffff:ffff:ffff:ffff
157ff2d:9c::/32ff2d:9c:ffff:ffff:ffff:ffff:ffff:ffff
158ff2d:9d::/32ff2d:9d:ffff:ffff:ffff:ffff:ffff:ffff
159ff2d:9e::/32ff2d:9e:ffff:ffff:ffff:ffff:ffff:ffff
160ff2d:9f::/32ff2d:9f:ffff:ffff:ffff:ffff:ffff:ffff
161ff2d:a0::/32ff2d:a0:ffff:ffff:ffff:ffff:ffff:ffff
162ff2d:a1::/32ff2d:a1:ffff:ffff:ffff:ffff:ffff:ffff
163ff2d:a2::/32ff2d:a2:ffff:ffff:ffff:ffff:ffff:ffff
164ff2d:a3::/32ff2d:a3:ffff:ffff:ffff:ffff:ffff:ffff
165ff2d:a4::/32ff2d:a4:ffff:ffff:ffff:ffff:ffff:ffff
166ff2d:a5::/32ff2d:a5:ffff:ffff:ffff:ffff:ffff:ffff
167ff2d:a6::/32ff2d:a6:ffff:ffff:ffff:ffff:ffff:ffff
168ff2d:a7::/32ff2d:a7:ffff:ffff:ffff:ffff:ffff:ffff
169ff2d:a8::/32ff2d:a8:ffff:ffff:ffff:ffff:ffff:ffff
170ff2d:a9::/32ff2d:a9:ffff:ffff:ffff:ffff:ffff:ffff
171ff2d:aa::/32ff2d:aa:ffff:ffff:ffff:ffff:ffff:ffff
172ff2d:ab::/32ff2d:ab:ffff:ffff:ffff:ffff:ffff:ffff
173ff2d:ac::/32ff2d:ac:ffff:ffff:ffff:ffff:ffff:ffff
174ff2d:ad::/32ff2d:ad:ffff:ffff:ffff:ffff:ffff:ffff
175ff2d:ae::/32ff2d:ae:ffff:ffff:ffff:ffff:ffff:ffff
176ff2d:af::/32ff2d:af:ffff:ffff:ffff:ffff:ffff:ffff
177ff2d:b0::/32ff2d:b0:ffff:ffff:ffff:ffff:ffff:ffff
178ff2d:b1::/32ff2d:b1:ffff:ffff:ffff:ffff:ffff:ffff
179ff2d:b2::/32ff2d:b2:ffff:ffff:ffff:ffff:ffff:ffff
180ff2d:b3::/32ff2d:b3:ffff:ffff:ffff:ffff:ffff:ffff
181ff2d:b4::/32ff2d:b4:ffff:ffff:ffff:ffff:ffff:ffff
182ff2d:b5::/32ff2d:b5:ffff:ffff:ffff:ffff:ffff:ffff
183ff2d:b6::/32ff2d:b6:ffff:ffff:ffff:ffff:ffff:ffff
184ff2d:b7::/32ff2d:b7:ffff:ffff:ffff:ffff:ffff:ffff
185ff2d:b8::/32ff2d:b8:ffff:ffff:ffff:ffff:ffff:ffff
186ff2d:b9::/32ff2d:b9:ffff:ffff:ffff:ffff:ffff:ffff
187ff2d:ba::/32ff2d:ba:ffff:ffff:ffff:ffff:ffff:ffff
188ff2d:bb::/32ff2d:bb:ffff:ffff:ffff:ffff:ffff:ffff
189ff2d:bc::/32ff2d:bc:ffff:ffff:ffff:ffff:ffff:ffff
190ff2d:bd::/32ff2d:bd:ffff:ffff:ffff:ffff:ffff:ffff
191ff2d:be::/32ff2d:be:ffff:ffff:ffff:ffff:ffff:ffff
192ff2d:bf::/32ff2d:bf:ffff:ffff:ffff:ffff:ffff:ffff
193ff2d:c0::/32ff2d:c0:ffff:ffff:ffff:ffff:ffff:ffff
194ff2d:c1::/32ff2d:c1:ffff:ffff:ffff:ffff:ffff:ffff
195ff2d:c2::/32ff2d:c2:ffff:ffff:ffff:ffff:ffff:ffff
196ff2d:c3::/32ff2d:c3:ffff:ffff:ffff:ffff:ffff:ffff
197ff2d:c4::/32ff2d:c4:ffff:ffff:ffff:ffff:ffff:ffff
198ff2d:c5::/32ff2d:c5:ffff:ffff:ffff:ffff:ffff:ffff
199ff2d:c6::/32ff2d:c6:ffff:ffff:ffff:ffff:ffff:ffff
200ff2d:c7::/32ff2d:c7:ffff:ffff:ffff:ffff:ffff:ffff
201ff2d:c8::/32ff2d:c8:ffff:ffff:ffff:ffff:ffff:ffff
202ff2d:c9::/32ff2d:c9:ffff:ffff:ffff:ffff:ffff:ffff
203ff2d:ca::/32ff2d:ca:ffff:ffff:ffff:ffff:ffff:ffff
204ff2d:cb::/32ff2d:cb:ffff:ffff:ffff:ffff:ffff:ffff
205ff2d:cc::/32ff2d:cc:ffff:ffff:ffff:ffff:ffff:ffff
206ff2d:cd::/32ff2d:cd:ffff:ffff:ffff:ffff:ffff:ffff
207ff2d:ce::/32ff2d:ce:ffff:ffff:ffff:ffff:ffff:ffff
208ff2d:cf::/32ff2d:cf:ffff:ffff:ffff:ffff:ffff:ffff
209ff2d:d0::/32ff2d:d0:ffff:ffff:ffff:ffff:ffff:ffff
210ff2d:d1::/32ff2d:d1:ffff:ffff:ffff:ffff:ffff:ffff
211ff2d:d2::/32ff2d:d2:ffff:ffff:ffff:ffff:ffff:ffff
212ff2d:d3::/32ff2d:d3:ffff:ffff:ffff:ffff:ffff:ffff
213ff2d:d4::/32ff2d:d4:ffff:ffff:ffff:ffff:ffff:ffff
214ff2d:d5::/32ff2d:d5:ffff:ffff:ffff:ffff:ffff:ffff
215ff2d:d6::/32ff2d:d6:ffff:ffff:ffff:ffff:ffff:ffff
216ff2d:d7::/32ff2d:d7:ffff:ffff:ffff:ffff:ffff:ffff
217ff2d:d8::/32ff2d:d8:ffff:ffff:ffff:ffff:ffff:ffff
218ff2d:d9::/32ff2d:d9:ffff:ffff:ffff:ffff:ffff:ffff
219ff2d:da::/32ff2d:da:ffff:ffff:ffff:ffff:ffff:ffff
220ff2d:db::/32ff2d:db:ffff:ffff:ffff:ffff:ffff:ffff
221ff2d:dc::/32ff2d:dc:ffff:ffff:ffff:ffff:ffff:ffff
222ff2d:dd::/32ff2d:dd:ffff:ffff:ffff:ffff:ffff:ffff
223ff2d:de::/32ff2d:de:ffff:ffff:ffff:ffff:ffff:ffff
224ff2d:df::/32ff2d:df:ffff:ffff:ffff:ffff:ffff:ffff
225ff2d:e0::/32ff2d:e0:ffff:ffff:ffff:ffff:ffff:ffff
226ff2d:e1::/32ff2d:e1:ffff:ffff:ffff:ffff:ffff:ffff
227ff2d:e2::/32ff2d:e2:ffff:ffff:ffff:ffff:ffff:ffff
228ff2d:e3::/32ff2d:e3:ffff:ffff:ffff:ffff:ffff:ffff
229ff2d:e4::/32ff2d:e4:ffff:ffff:ffff:ffff:ffff:ffff
230ff2d:e5::/32ff2d:e5:ffff:ffff:ffff:ffff:ffff:ffff
231ff2d:e6::/32ff2d:e6:ffff:ffff:ffff:ffff:ffff:ffff
232ff2d:e7::/32ff2d:e7:ffff:ffff:ffff:ffff:ffff:ffff
233ff2d:e8::/32ff2d:e8:ffff:ffff:ffff:ffff:ffff:ffff
234ff2d:e9::/32ff2d:e9:ffff:ffff:ffff:ffff:ffff:ffff
235ff2d:ea::/32ff2d:ea:ffff:ffff:ffff:ffff:ffff:ffff
236ff2d:eb::/32ff2d:eb:ffff:ffff:ffff:ffff:ffff:ffff
237ff2d:ec::/32ff2d:ec:ffff:ffff:ffff:ffff:ffff:ffff
238ff2d:ed::/32ff2d:ed:ffff:ffff:ffff:ffff:ffff:ffff
239ff2d:ee::/32ff2d:ee:ffff:ffff:ffff:ffff:ffff:ffff
240ff2d:ef::/32ff2d:ef:ffff:ffff:ffff:ffff:ffff:ffff
241ff2d:f0::/32ff2d:f0:ffff:ffff:ffff:ffff:ffff:ffff
242ff2d:f1::/32ff2d:f1:ffff:ffff:ffff:ffff:ffff:ffff
243ff2d:f2::/32ff2d:f2:ffff:ffff:ffff:ffff:ffff:ffff
244ff2d:f3::/32ff2d:f3:ffff:ffff:ffff:ffff:ffff:ffff
245ff2d:f4::/32ff2d:f4:ffff:ffff:ffff:ffff:ffff:ffff
246ff2d:f5::/32ff2d:f5:ffff:ffff:ffff:ffff:ffff:ffff
247ff2d:f6::/32ff2d:f6:ffff:ffff:ffff:ffff:ffff:ffff
248ff2d:f7::/32ff2d:f7:ffff:ffff:ffff:ffff:ffff:ffff
249ff2d:f8::/32ff2d:f8:ffff:ffff:ffff:ffff:ffff:ffff
250ff2d:f9::/32ff2d:f9:ffff:ffff:ffff:ffff:ffff:ffff
251ff2d:fa::/32ff2d:fa:ffff:ffff:ffff:ffff:ffff:ffff
252ff2d:fb::/32ff2d:fb:ffff:ffff:ffff:ffff:ffff:ffff
253ff2d:fc::/32ff2d:fc:ffff:ffff:ffff:ffff:ffff:ffff
254ff2d:fd::/32ff2d:fd:ffff:ffff:ffff:ffff:ffff:ffff
255ff2d:fe::/32ff2d:fe:ffff:ffff:ffff:ffff:ffff:ffff
256ff2d:ff::/32ff2d: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.