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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/20
Addresses2^108
/64 networks2^44
Network
ff0f::/20
First address
ff0f::
Last address
ff0f:fff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
324,518,553,658,426,726,783,156,020,576,256 (2^108)
/64 networks (LANs)
17,592,186,044,416 (2^44)
Full form
ff0f:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
0.f.0.f.f.ip6.arpa
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

ff0f::/20 makes 256 subnets of /28.

Subnets
#SubnetLast address
1ff0f::/28ff0f:f:ffff:ffff:ffff:ffff:ffff:ffff
2ff0f:10::/28ff0f:1f:ffff:ffff:ffff:ffff:ffff:ffff
3ff0f:20::/28ff0f:2f:ffff:ffff:ffff:ffff:ffff:ffff
4ff0f:30::/28ff0f:3f:ffff:ffff:ffff:ffff:ffff:ffff
5ff0f:40::/28ff0f:4f:ffff:ffff:ffff:ffff:ffff:ffff
6ff0f:50::/28ff0f:5f:ffff:ffff:ffff:ffff:ffff:ffff
7ff0f:60::/28ff0f:6f:ffff:ffff:ffff:ffff:ffff:ffff
8ff0f:70::/28ff0f:7f:ffff:ffff:ffff:ffff:ffff:ffff
9ff0f:80::/28ff0f:8f:ffff:ffff:ffff:ffff:ffff:ffff
10ff0f:90::/28ff0f:9f:ffff:ffff:ffff:ffff:ffff:ffff
11ff0f:a0::/28ff0f:af:ffff:ffff:ffff:ffff:ffff:ffff
12ff0f:b0::/28ff0f:bf:ffff:ffff:ffff:ffff:ffff:ffff
13ff0f:c0::/28ff0f:cf:ffff:ffff:ffff:ffff:ffff:ffff
14ff0f:d0::/28ff0f:df:ffff:ffff:ffff:ffff:ffff:ffff
15ff0f:e0::/28ff0f:ef:ffff:ffff:ffff:ffff:ffff:ffff
16ff0f:f0::/28ff0f:ff:ffff:ffff:ffff:ffff:ffff:ffff
17ff0f:100::/28ff0f:10f:ffff:ffff:ffff:ffff:ffff:ffff
18ff0f:110::/28ff0f:11f:ffff:ffff:ffff:ffff:ffff:ffff
19ff0f:120::/28ff0f:12f:ffff:ffff:ffff:ffff:ffff:ffff
20ff0f:130::/28ff0f:13f:ffff:ffff:ffff:ffff:ffff:ffff
21ff0f:140::/28ff0f:14f:ffff:ffff:ffff:ffff:ffff:ffff
22ff0f:150::/28ff0f:15f:ffff:ffff:ffff:ffff:ffff:ffff
23ff0f:160::/28ff0f:16f:ffff:ffff:ffff:ffff:ffff:ffff
24ff0f:170::/28ff0f:17f:ffff:ffff:ffff:ffff:ffff:ffff
25ff0f:180::/28ff0f:18f:ffff:ffff:ffff:ffff:ffff:ffff
26ff0f:190::/28ff0f:19f:ffff:ffff:ffff:ffff:ffff:ffff
27ff0f:1a0::/28ff0f:1af:ffff:ffff:ffff:ffff:ffff:ffff
28ff0f:1b0::/28ff0f:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29ff0f:1c0::/28ff0f:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30ff0f:1d0::/28ff0f:1df:ffff:ffff:ffff:ffff:ffff:ffff
31ff0f:1e0::/28ff0f:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32ff0f:1f0::/28ff0f:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33ff0f:200::/28ff0f:20f:ffff:ffff:ffff:ffff:ffff:ffff
34ff0f:210::/28ff0f:21f:ffff:ffff:ffff:ffff:ffff:ffff
35ff0f:220::/28ff0f:22f:ffff:ffff:ffff:ffff:ffff:ffff
36ff0f:230::/28ff0f:23f:ffff:ffff:ffff:ffff:ffff:ffff
37ff0f:240::/28ff0f:24f:ffff:ffff:ffff:ffff:ffff:ffff
38ff0f:250::/28ff0f:25f:ffff:ffff:ffff:ffff:ffff:ffff
39ff0f:260::/28ff0f:26f:ffff:ffff:ffff:ffff:ffff:ffff
40ff0f:270::/28ff0f:27f:ffff:ffff:ffff:ffff:ffff:ffff
41ff0f:280::/28ff0f:28f:ffff:ffff:ffff:ffff:ffff:ffff
42ff0f:290::/28ff0f:29f:ffff:ffff:ffff:ffff:ffff:ffff
43ff0f:2a0::/28ff0f:2af:ffff:ffff:ffff:ffff:ffff:ffff
44ff0f:2b0::/28ff0f:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45ff0f:2c0::/28ff0f:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46ff0f:2d0::/28ff0f:2df:ffff:ffff:ffff:ffff:ffff:ffff
47ff0f:2e0::/28ff0f:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48ff0f:2f0::/28ff0f:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49ff0f:300::/28ff0f:30f:ffff:ffff:ffff:ffff:ffff:ffff
50ff0f:310::/28ff0f:31f:ffff:ffff:ffff:ffff:ffff:ffff
51ff0f:320::/28ff0f:32f:ffff:ffff:ffff:ffff:ffff:ffff
52ff0f:330::/28ff0f:33f:ffff:ffff:ffff:ffff:ffff:ffff
53ff0f:340::/28ff0f:34f:ffff:ffff:ffff:ffff:ffff:ffff
54ff0f:350::/28ff0f:35f:ffff:ffff:ffff:ffff:ffff:ffff
55ff0f:360::/28ff0f:36f:ffff:ffff:ffff:ffff:ffff:ffff
56ff0f:370::/28ff0f:37f:ffff:ffff:ffff:ffff:ffff:ffff
57ff0f:380::/28ff0f:38f:ffff:ffff:ffff:ffff:ffff:ffff
58ff0f:390::/28ff0f:39f:ffff:ffff:ffff:ffff:ffff:ffff
59ff0f:3a0::/28ff0f:3af:ffff:ffff:ffff:ffff:ffff:ffff
60ff0f:3b0::/28ff0f:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61ff0f:3c0::/28ff0f:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62ff0f:3d0::/28ff0f:3df:ffff:ffff:ffff:ffff:ffff:ffff
63ff0f:3e0::/28ff0f:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64ff0f:3f0::/28ff0f:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65ff0f:400::/28ff0f:40f:ffff:ffff:ffff:ffff:ffff:ffff
66ff0f:410::/28ff0f:41f:ffff:ffff:ffff:ffff:ffff:ffff
67ff0f:420::/28ff0f:42f:ffff:ffff:ffff:ffff:ffff:ffff
68ff0f:430::/28ff0f:43f:ffff:ffff:ffff:ffff:ffff:ffff
69ff0f:440::/28ff0f:44f:ffff:ffff:ffff:ffff:ffff:ffff
70ff0f:450::/28ff0f:45f:ffff:ffff:ffff:ffff:ffff:ffff
71ff0f:460::/28ff0f:46f:ffff:ffff:ffff:ffff:ffff:ffff
72ff0f:470::/28ff0f:47f:ffff:ffff:ffff:ffff:ffff:ffff
73ff0f:480::/28ff0f:48f:ffff:ffff:ffff:ffff:ffff:ffff
74ff0f:490::/28ff0f:49f:ffff:ffff:ffff:ffff:ffff:ffff
75ff0f:4a0::/28ff0f:4af:ffff:ffff:ffff:ffff:ffff:ffff
76ff0f:4b0::/28ff0f:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77ff0f:4c0::/28ff0f:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78ff0f:4d0::/28ff0f:4df:ffff:ffff:ffff:ffff:ffff:ffff
79ff0f:4e0::/28ff0f:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80ff0f:4f0::/28ff0f:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81ff0f:500::/28ff0f:50f:ffff:ffff:ffff:ffff:ffff:ffff
82ff0f:510::/28ff0f:51f:ffff:ffff:ffff:ffff:ffff:ffff
83ff0f:520::/28ff0f:52f:ffff:ffff:ffff:ffff:ffff:ffff
84ff0f:530::/28ff0f:53f:ffff:ffff:ffff:ffff:ffff:ffff
85ff0f:540::/28ff0f:54f:ffff:ffff:ffff:ffff:ffff:ffff
86ff0f:550::/28ff0f:55f:ffff:ffff:ffff:ffff:ffff:ffff
87ff0f:560::/28ff0f:56f:ffff:ffff:ffff:ffff:ffff:ffff
88ff0f:570::/28ff0f:57f:ffff:ffff:ffff:ffff:ffff:ffff
89ff0f:580::/28ff0f:58f:ffff:ffff:ffff:ffff:ffff:ffff
90ff0f:590::/28ff0f:59f:ffff:ffff:ffff:ffff:ffff:ffff
91ff0f:5a0::/28ff0f:5af:ffff:ffff:ffff:ffff:ffff:ffff
92ff0f:5b0::/28ff0f:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93ff0f:5c0::/28ff0f:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94ff0f:5d0::/28ff0f:5df:ffff:ffff:ffff:ffff:ffff:ffff
95ff0f:5e0::/28ff0f:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96ff0f:5f0::/28ff0f:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97ff0f:600::/28ff0f:60f:ffff:ffff:ffff:ffff:ffff:ffff
98ff0f:610::/28ff0f:61f:ffff:ffff:ffff:ffff:ffff:ffff
99ff0f:620::/28ff0f:62f:ffff:ffff:ffff:ffff:ffff:ffff
100ff0f:630::/28ff0f:63f:ffff:ffff:ffff:ffff:ffff:ffff
101ff0f:640::/28ff0f:64f:ffff:ffff:ffff:ffff:ffff:ffff
102ff0f:650::/28ff0f:65f:ffff:ffff:ffff:ffff:ffff:ffff
103ff0f:660::/28ff0f:66f:ffff:ffff:ffff:ffff:ffff:ffff
104ff0f:670::/28ff0f:67f:ffff:ffff:ffff:ffff:ffff:ffff
105ff0f:680::/28ff0f:68f:ffff:ffff:ffff:ffff:ffff:ffff
106ff0f:690::/28ff0f:69f:ffff:ffff:ffff:ffff:ffff:ffff
107ff0f:6a0::/28ff0f:6af:ffff:ffff:ffff:ffff:ffff:ffff
108ff0f:6b0::/28ff0f:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109ff0f:6c0::/28ff0f:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110ff0f:6d0::/28ff0f:6df:ffff:ffff:ffff:ffff:ffff:ffff
111ff0f:6e0::/28ff0f:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112ff0f:6f0::/28ff0f:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113ff0f:700::/28ff0f:70f:ffff:ffff:ffff:ffff:ffff:ffff
114ff0f:710::/28ff0f:71f:ffff:ffff:ffff:ffff:ffff:ffff
115ff0f:720::/28ff0f:72f:ffff:ffff:ffff:ffff:ffff:ffff
116ff0f:730::/28ff0f:73f:ffff:ffff:ffff:ffff:ffff:ffff
117ff0f:740::/28ff0f:74f:ffff:ffff:ffff:ffff:ffff:ffff
118ff0f:750::/28ff0f:75f:ffff:ffff:ffff:ffff:ffff:ffff
119ff0f:760::/28ff0f:76f:ffff:ffff:ffff:ffff:ffff:ffff
120ff0f:770::/28ff0f:77f:ffff:ffff:ffff:ffff:ffff:ffff
121ff0f:780::/28ff0f:78f:ffff:ffff:ffff:ffff:ffff:ffff
122ff0f:790::/28ff0f:79f:ffff:ffff:ffff:ffff:ffff:ffff
123ff0f:7a0::/28ff0f:7af:ffff:ffff:ffff:ffff:ffff:ffff
124ff0f:7b0::/28ff0f:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125ff0f:7c0::/28ff0f:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126ff0f:7d0::/28ff0f:7df:ffff:ffff:ffff:ffff:ffff:ffff
127ff0f:7e0::/28ff0f:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128ff0f:7f0::/28ff0f:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129ff0f:800::/28ff0f:80f:ffff:ffff:ffff:ffff:ffff:ffff
130ff0f:810::/28ff0f:81f:ffff:ffff:ffff:ffff:ffff:ffff
131ff0f:820::/28ff0f:82f:ffff:ffff:ffff:ffff:ffff:ffff
132ff0f:830::/28ff0f:83f:ffff:ffff:ffff:ffff:ffff:ffff
133ff0f:840::/28ff0f:84f:ffff:ffff:ffff:ffff:ffff:ffff
134ff0f:850::/28ff0f:85f:ffff:ffff:ffff:ffff:ffff:ffff
135ff0f:860::/28ff0f:86f:ffff:ffff:ffff:ffff:ffff:ffff
136ff0f:870::/28ff0f:87f:ffff:ffff:ffff:ffff:ffff:ffff
137ff0f:880::/28ff0f:88f:ffff:ffff:ffff:ffff:ffff:ffff
138ff0f:890::/28ff0f:89f:ffff:ffff:ffff:ffff:ffff:ffff
139ff0f:8a0::/28ff0f:8af:ffff:ffff:ffff:ffff:ffff:ffff
140ff0f:8b0::/28ff0f:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141ff0f:8c0::/28ff0f:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142ff0f:8d0::/28ff0f:8df:ffff:ffff:ffff:ffff:ffff:ffff
143ff0f:8e0::/28ff0f:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144ff0f:8f0::/28ff0f:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145ff0f:900::/28ff0f:90f:ffff:ffff:ffff:ffff:ffff:ffff
146ff0f:910::/28ff0f:91f:ffff:ffff:ffff:ffff:ffff:ffff
147ff0f:920::/28ff0f:92f:ffff:ffff:ffff:ffff:ffff:ffff
148ff0f:930::/28ff0f:93f:ffff:ffff:ffff:ffff:ffff:ffff
149ff0f:940::/28ff0f:94f:ffff:ffff:ffff:ffff:ffff:ffff
150ff0f:950::/28ff0f:95f:ffff:ffff:ffff:ffff:ffff:ffff
151ff0f:960::/28ff0f:96f:ffff:ffff:ffff:ffff:ffff:ffff
152ff0f:970::/28ff0f:97f:ffff:ffff:ffff:ffff:ffff:ffff
153ff0f:980::/28ff0f:98f:ffff:ffff:ffff:ffff:ffff:ffff
154ff0f:990::/28ff0f:99f:ffff:ffff:ffff:ffff:ffff:ffff
155ff0f:9a0::/28ff0f:9af:ffff:ffff:ffff:ffff:ffff:ffff
156ff0f:9b0::/28ff0f:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157ff0f:9c0::/28ff0f:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158ff0f:9d0::/28ff0f:9df:ffff:ffff:ffff:ffff:ffff:ffff
159ff0f:9e0::/28ff0f:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160ff0f:9f0::/28ff0f:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161ff0f:a00::/28ff0f:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162ff0f:a10::/28ff0f:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163ff0f:a20::/28ff0f:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164ff0f:a30::/28ff0f:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165ff0f:a40::/28ff0f:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166ff0f:a50::/28ff0f:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167ff0f:a60::/28ff0f:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168ff0f:a70::/28ff0f:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169ff0f:a80::/28ff0f:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170ff0f:a90::/28ff0f:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171ff0f:aa0::/28ff0f:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172ff0f:ab0::/28ff0f:abf:ffff:ffff:ffff:ffff:ffff:ffff
173ff0f:ac0::/28ff0f:acf:ffff:ffff:ffff:ffff:ffff:ffff
174ff0f:ad0::/28ff0f:adf:ffff:ffff:ffff:ffff:ffff:ffff
175ff0f:ae0::/28ff0f:aef:ffff:ffff:ffff:ffff:ffff:ffff
176ff0f:af0::/28ff0f:aff:ffff:ffff:ffff:ffff:ffff:ffff
177ff0f:b00::/28ff0f:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178ff0f:b10::/28ff0f:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179ff0f:b20::/28ff0f:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180ff0f:b30::/28ff0f:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181ff0f:b40::/28ff0f:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182ff0f:b50::/28ff0f:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183ff0f:b60::/28ff0f:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184ff0f:b70::/28ff0f:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185ff0f:b80::/28ff0f:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186ff0f:b90::/28ff0f:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187ff0f:ba0::/28ff0f:baf:ffff:ffff:ffff:ffff:ffff:ffff
188ff0f:bb0::/28ff0f:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189ff0f:bc0::/28ff0f:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190ff0f:bd0::/28ff0f:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191ff0f:be0::/28ff0f:bef:ffff:ffff:ffff:ffff:ffff:ffff
192ff0f:bf0::/28ff0f:bff:ffff:ffff:ffff:ffff:ffff:ffff
193ff0f:c00::/28ff0f:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194ff0f:c10::/28ff0f:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195ff0f:c20::/28ff0f:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196ff0f:c30::/28ff0f:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197ff0f:c40::/28ff0f:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198ff0f:c50::/28ff0f:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199ff0f:c60::/28ff0f:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200ff0f:c70::/28ff0f:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201ff0f:c80::/28ff0f:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202ff0f:c90::/28ff0f:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203ff0f:ca0::/28ff0f:caf:ffff:ffff:ffff:ffff:ffff:ffff
204ff0f:cb0::/28ff0f:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205ff0f:cc0::/28ff0f:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206ff0f:cd0::/28ff0f:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207ff0f:ce0::/28ff0f:cef:ffff:ffff:ffff:ffff:ffff:ffff
208ff0f:cf0::/28ff0f:cff:ffff:ffff:ffff:ffff:ffff:ffff
209ff0f:d00::/28ff0f:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210ff0f:d10::/28ff0f:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211ff0f:d20::/28ff0f:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212ff0f:d30::/28ff0f:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213ff0f:d40::/28ff0f:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214ff0f:d50::/28ff0f:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215ff0f:d60::/28ff0f:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216ff0f:d70::/28ff0f:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217ff0f:d80::/28ff0f:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218ff0f:d90::/28ff0f:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219ff0f:da0::/28ff0f:daf:ffff:ffff:ffff:ffff:ffff:ffff
220ff0f:db0::/28ff0f:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221ff0f:dc0::/28ff0f:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222ff0f:dd0::/28ff0f:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223ff0f:de0::/28ff0f:def:ffff:ffff:ffff:ffff:ffff:ffff
224ff0f:df0::/28ff0f:dff:ffff:ffff:ffff:ffff:ffff:ffff
225ff0f:e00::/28ff0f:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226ff0f:e10::/28ff0f:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227ff0f:e20::/28ff0f:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228ff0f:e30::/28ff0f:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229ff0f:e40::/28ff0f:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230ff0f:e50::/28ff0f:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231ff0f:e60::/28ff0f:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232ff0f:e70::/28ff0f:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233ff0f:e80::/28ff0f:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234ff0f:e90::/28ff0f:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235ff0f:ea0::/28ff0f:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236ff0f:eb0::/28ff0f:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237ff0f:ec0::/28ff0f:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238ff0f:ed0::/28ff0f:edf:ffff:ffff:ffff:ffff:ffff:ffff
239ff0f:ee0::/28ff0f:eef:ffff:ffff:ffff:ffff:ffff:ffff
240ff0f:ef0::/28ff0f:eff:ffff:ffff:ffff:ffff:ffff:ffff
241ff0f:f00::/28ff0f:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242ff0f:f10::/28ff0f:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243ff0f:f20::/28ff0f:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244ff0f:f30::/28ff0f:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245ff0f:f40::/28ff0f:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246ff0f:f50::/28ff0f:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247ff0f:f60::/28ff0f:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248ff0f:f70::/28ff0f:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249ff0f:f80::/28ff0f:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250ff0f:f90::/28ff0f:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251ff0f:fa0::/28ff0f:faf:ffff:ffff:ffff:ffff:ffff:ffff
252ff0f:fb0::/28ff0f:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253ff0f:fc0::/28ff0f:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254ff0f:fd0::/28ff0f:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255ff0f:fe0::/28ff0f:fef:ffff:ffff:ffff:ffff:ffff:ffff
256ff0f:ff0::/28ff0f:fff: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.