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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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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
ff2b::/16
First address
ff2b::
Last address
ff2b: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
ff2b:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
b.2.f.f.ip6.arpa
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ff2b::/16 makes 4,096 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
1ff2b::/28ff2b:f:ffff:ffff:ffff:ffff:ffff:ffff
2ff2b:10::/28ff2b:1f:ffff:ffff:ffff:ffff:ffff:ffff
3ff2b:20::/28ff2b:2f:ffff:ffff:ffff:ffff:ffff:ffff
4ff2b:30::/28ff2b:3f:ffff:ffff:ffff:ffff:ffff:ffff
5ff2b:40::/28ff2b:4f:ffff:ffff:ffff:ffff:ffff:ffff
6ff2b:50::/28ff2b:5f:ffff:ffff:ffff:ffff:ffff:ffff
7ff2b:60::/28ff2b:6f:ffff:ffff:ffff:ffff:ffff:ffff
8ff2b:70::/28ff2b:7f:ffff:ffff:ffff:ffff:ffff:ffff
9ff2b:80::/28ff2b:8f:ffff:ffff:ffff:ffff:ffff:ffff
10ff2b:90::/28ff2b:9f:ffff:ffff:ffff:ffff:ffff:ffff
11ff2b:a0::/28ff2b:af:ffff:ffff:ffff:ffff:ffff:ffff
12ff2b:b0::/28ff2b:bf:ffff:ffff:ffff:ffff:ffff:ffff
13ff2b:c0::/28ff2b:cf:ffff:ffff:ffff:ffff:ffff:ffff
14ff2b:d0::/28ff2b:df:ffff:ffff:ffff:ffff:ffff:ffff
15ff2b:e0::/28ff2b:ef:ffff:ffff:ffff:ffff:ffff:ffff
16ff2b:f0::/28ff2b:ff:ffff:ffff:ffff:ffff:ffff:ffff
17ff2b:100::/28ff2b:10f:ffff:ffff:ffff:ffff:ffff:ffff
18ff2b:110::/28ff2b:11f:ffff:ffff:ffff:ffff:ffff:ffff
19ff2b:120::/28ff2b:12f:ffff:ffff:ffff:ffff:ffff:ffff
20ff2b:130::/28ff2b:13f:ffff:ffff:ffff:ffff:ffff:ffff
21ff2b:140::/28ff2b:14f:ffff:ffff:ffff:ffff:ffff:ffff
22ff2b:150::/28ff2b:15f:ffff:ffff:ffff:ffff:ffff:ffff
23ff2b:160::/28ff2b:16f:ffff:ffff:ffff:ffff:ffff:ffff
24ff2b:170::/28ff2b:17f:ffff:ffff:ffff:ffff:ffff:ffff
25ff2b:180::/28ff2b:18f:ffff:ffff:ffff:ffff:ffff:ffff
26ff2b:190::/28ff2b:19f:ffff:ffff:ffff:ffff:ffff:ffff
27ff2b:1a0::/28ff2b:1af:ffff:ffff:ffff:ffff:ffff:ffff
28ff2b:1b0::/28ff2b:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29ff2b:1c0::/28ff2b:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30ff2b:1d0::/28ff2b:1df:ffff:ffff:ffff:ffff:ffff:ffff
31ff2b:1e0::/28ff2b:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32ff2b:1f0::/28ff2b:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33ff2b:200::/28ff2b:20f:ffff:ffff:ffff:ffff:ffff:ffff
34ff2b:210::/28ff2b:21f:ffff:ffff:ffff:ffff:ffff:ffff
35ff2b:220::/28ff2b:22f:ffff:ffff:ffff:ffff:ffff:ffff
36ff2b:230::/28ff2b:23f:ffff:ffff:ffff:ffff:ffff:ffff
37ff2b:240::/28ff2b:24f:ffff:ffff:ffff:ffff:ffff:ffff
38ff2b:250::/28ff2b:25f:ffff:ffff:ffff:ffff:ffff:ffff
39ff2b:260::/28ff2b:26f:ffff:ffff:ffff:ffff:ffff:ffff
40ff2b:270::/28ff2b:27f:ffff:ffff:ffff:ffff:ffff:ffff
41ff2b:280::/28ff2b:28f:ffff:ffff:ffff:ffff:ffff:ffff
42ff2b:290::/28ff2b:29f:ffff:ffff:ffff:ffff:ffff:ffff
43ff2b:2a0::/28ff2b:2af:ffff:ffff:ffff:ffff:ffff:ffff
44ff2b:2b0::/28ff2b:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45ff2b:2c0::/28ff2b:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46ff2b:2d0::/28ff2b:2df:ffff:ffff:ffff:ffff:ffff:ffff
47ff2b:2e0::/28ff2b:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48ff2b:2f0::/28ff2b:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49ff2b:300::/28ff2b:30f:ffff:ffff:ffff:ffff:ffff:ffff
50ff2b:310::/28ff2b:31f:ffff:ffff:ffff:ffff:ffff:ffff
51ff2b:320::/28ff2b:32f:ffff:ffff:ffff:ffff:ffff:ffff
52ff2b:330::/28ff2b:33f:ffff:ffff:ffff:ffff:ffff:ffff
53ff2b:340::/28ff2b:34f:ffff:ffff:ffff:ffff:ffff:ffff
54ff2b:350::/28ff2b:35f:ffff:ffff:ffff:ffff:ffff:ffff
55ff2b:360::/28ff2b:36f:ffff:ffff:ffff:ffff:ffff:ffff
56ff2b:370::/28ff2b:37f:ffff:ffff:ffff:ffff:ffff:ffff
57ff2b:380::/28ff2b:38f:ffff:ffff:ffff:ffff:ffff:ffff
58ff2b:390::/28ff2b:39f:ffff:ffff:ffff:ffff:ffff:ffff
59ff2b:3a0::/28ff2b:3af:ffff:ffff:ffff:ffff:ffff:ffff
60ff2b:3b0::/28ff2b:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61ff2b:3c0::/28ff2b:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62ff2b:3d0::/28ff2b:3df:ffff:ffff:ffff:ffff:ffff:ffff
63ff2b:3e0::/28ff2b:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64ff2b:3f0::/28ff2b:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65ff2b:400::/28ff2b:40f:ffff:ffff:ffff:ffff:ffff:ffff
66ff2b:410::/28ff2b:41f:ffff:ffff:ffff:ffff:ffff:ffff
67ff2b:420::/28ff2b:42f:ffff:ffff:ffff:ffff:ffff:ffff
68ff2b:430::/28ff2b:43f:ffff:ffff:ffff:ffff:ffff:ffff
69ff2b:440::/28ff2b:44f:ffff:ffff:ffff:ffff:ffff:ffff
70ff2b:450::/28ff2b:45f:ffff:ffff:ffff:ffff:ffff:ffff
71ff2b:460::/28ff2b:46f:ffff:ffff:ffff:ffff:ffff:ffff
72ff2b:470::/28ff2b:47f:ffff:ffff:ffff:ffff:ffff:ffff
73ff2b:480::/28ff2b:48f:ffff:ffff:ffff:ffff:ffff:ffff
74ff2b:490::/28ff2b:49f:ffff:ffff:ffff:ffff:ffff:ffff
75ff2b:4a0::/28ff2b:4af:ffff:ffff:ffff:ffff:ffff:ffff
76ff2b:4b0::/28ff2b:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77ff2b:4c0::/28ff2b:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78ff2b:4d0::/28ff2b:4df:ffff:ffff:ffff:ffff:ffff:ffff
79ff2b:4e0::/28ff2b:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80ff2b:4f0::/28ff2b:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81ff2b:500::/28ff2b:50f:ffff:ffff:ffff:ffff:ffff:ffff
82ff2b:510::/28ff2b:51f:ffff:ffff:ffff:ffff:ffff:ffff
83ff2b:520::/28ff2b:52f:ffff:ffff:ffff:ffff:ffff:ffff
84ff2b:530::/28ff2b:53f:ffff:ffff:ffff:ffff:ffff:ffff
85ff2b:540::/28ff2b:54f:ffff:ffff:ffff:ffff:ffff:ffff
86ff2b:550::/28ff2b:55f:ffff:ffff:ffff:ffff:ffff:ffff
87ff2b:560::/28ff2b:56f:ffff:ffff:ffff:ffff:ffff:ffff
88ff2b:570::/28ff2b:57f:ffff:ffff:ffff:ffff:ffff:ffff
89ff2b:580::/28ff2b:58f:ffff:ffff:ffff:ffff:ffff:ffff
90ff2b:590::/28ff2b:59f:ffff:ffff:ffff:ffff:ffff:ffff
91ff2b:5a0::/28ff2b:5af:ffff:ffff:ffff:ffff:ffff:ffff
92ff2b:5b0::/28ff2b:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93ff2b:5c0::/28ff2b:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94ff2b:5d0::/28ff2b:5df:ffff:ffff:ffff:ffff:ffff:ffff
95ff2b:5e0::/28ff2b:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96ff2b:5f0::/28ff2b:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97ff2b:600::/28ff2b:60f:ffff:ffff:ffff:ffff:ffff:ffff
98ff2b:610::/28ff2b:61f:ffff:ffff:ffff:ffff:ffff:ffff
99ff2b:620::/28ff2b:62f:ffff:ffff:ffff:ffff:ffff:ffff
100ff2b:630::/28ff2b:63f:ffff:ffff:ffff:ffff:ffff:ffff
101ff2b:640::/28ff2b:64f:ffff:ffff:ffff:ffff:ffff:ffff
102ff2b:650::/28ff2b:65f:ffff:ffff:ffff:ffff:ffff:ffff
103ff2b:660::/28ff2b:66f:ffff:ffff:ffff:ffff:ffff:ffff
104ff2b:670::/28ff2b:67f:ffff:ffff:ffff:ffff:ffff:ffff
105ff2b:680::/28ff2b:68f:ffff:ffff:ffff:ffff:ffff:ffff
106ff2b:690::/28ff2b:69f:ffff:ffff:ffff:ffff:ffff:ffff
107ff2b:6a0::/28ff2b:6af:ffff:ffff:ffff:ffff:ffff:ffff
108ff2b:6b0::/28ff2b:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109ff2b:6c0::/28ff2b:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110ff2b:6d0::/28ff2b:6df:ffff:ffff:ffff:ffff:ffff:ffff
111ff2b:6e0::/28ff2b:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112ff2b:6f0::/28ff2b:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113ff2b:700::/28ff2b:70f:ffff:ffff:ffff:ffff:ffff:ffff
114ff2b:710::/28ff2b:71f:ffff:ffff:ffff:ffff:ffff:ffff
115ff2b:720::/28ff2b:72f:ffff:ffff:ffff:ffff:ffff:ffff
116ff2b:730::/28ff2b:73f:ffff:ffff:ffff:ffff:ffff:ffff
117ff2b:740::/28ff2b:74f:ffff:ffff:ffff:ffff:ffff:ffff
118ff2b:750::/28ff2b:75f:ffff:ffff:ffff:ffff:ffff:ffff
119ff2b:760::/28ff2b:76f:ffff:ffff:ffff:ffff:ffff:ffff
120ff2b:770::/28ff2b:77f:ffff:ffff:ffff:ffff:ffff:ffff
121ff2b:780::/28ff2b:78f:ffff:ffff:ffff:ffff:ffff:ffff
122ff2b:790::/28ff2b:79f:ffff:ffff:ffff:ffff:ffff:ffff
123ff2b:7a0::/28ff2b:7af:ffff:ffff:ffff:ffff:ffff:ffff
124ff2b:7b0::/28ff2b:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125ff2b:7c0::/28ff2b:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126ff2b:7d0::/28ff2b:7df:ffff:ffff:ffff:ffff:ffff:ffff
127ff2b:7e0::/28ff2b:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128ff2b:7f0::/28ff2b:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129ff2b:800::/28ff2b:80f:ffff:ffff:ffff:ffff:ffff:ffff
130ff2b:810::/28ff2b:81f:ffff:ffff:ffff:ffff:ffff:ffff
131ff2b:820::/28ff2b:82f:ffff:ffff:ffff:ffff:ffff:ffff
132ff2b:830::/28ff2b:83f:ffff:ffff:ffff:ffff:ffff:ffff
133ff2b:840::/28ff2b:84f:ffff:ffff:ffff:ffff:ffff:ffff
134ff2b:850::/28ff2b:85f:ffff:ffff:ffff:ffff:ffff:ffff
135ff2b:860::/28ff2b:86f:ffff:ffff:ffff:ffff:ffff:ffff
136ff2b:870::/28ff2b:87f:ffff:ffff:ffff:ffff:ffff:ffff
137ff2b:880::/28ff2b:88f:ffff:ffff:ffff:ffff:ffff:ffff
138ff2b:890::/28ff2b:89f:ffff:ffff:ffff:ffff:ffff:ffff
139ff2b:8a0::/28ff2b:8af:ffff:ffff:ffff:ffff:ffff:ffff
140ff2b:8b0::/28ff2b:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141ff2b:8c0::/28ff2b:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142ff2b:8d0::/28ff2b:8df:ffff:ffff:ffff:ffff:ffff:ffff
143ff2b:8e0::/28ff2b:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144ff2b:8f0::/28ff2b:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145ff2b:900::/28ff2b:90f:ffff:ffff:ffff:ffff:ffff:ffff
146ff2b:910::/28ff2b:91f:ffff:ffff:ffff:ffff:ffff:ffff
147ff2b:920::/28ff2b:92f:ffff:ffff:ffff:ffff:ffff:ffff
148ff2b:930::/28ff2b:93f:ffff:ffff:ffff:ffff:ffff:ffff
149ff2b:940::/28ff2b:94f:ffff:ffff:ffff:ffff:ffff:ffff
150ff2b:950::/28ff2b:95f:ffff:ffff:ffff:ffff:ffff:ffff
151ff2b:960::/28ff2b:96f:ffff:ffff:ffff:ffff:ffff:ffff
152ff2b:970::/28ff2b:97f:ffff:ffff:ffff:ffff:ffff:ffff
153ff2b:980::/28ff2b:98f:ffff:ffff:ffff:ffff:ffff:ffff
154ff2b:990::/28ff2b:99f:ffff:ffff:ffff:ffff:ffff:ffff
155ff2b:9a0::/28ff2b:9af:ffff:ffff:ffff:ffff:ffff:ffff
156ff2b:9b0::/28ff2b:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157ff2b:9c0::/28ff2b:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158ff2b:9d0::/28ff2b:9df:ffff:ffff:ffff:ffff:ffff:ffff
159ff2b:9e0::/28ff2b:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160ff2b:9f0::/28ff2b:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161ff2b:a00::/28ff2b:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162ff2b:a10::/28ff2b:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163ff2b:a20::/28ff2b:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164ff2b:a30::/28ff2b:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165ff2b:a40::/28ff2b:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166ff2b:a50::/28ff2b:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167ff2b:a60::/28ff2b:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168ff2b:a70::/28ff2b:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169ff2b:a80::/28ff2b:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170ff2b:a90::/28ff2b:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171ff2b:aa0::/28ff2b:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172ff2b:ab0::/28ff2b:abf:ffff:ffff:ffff:ffff:ffff:ffff
173ff2b:ac0::/28ff2b:acf:ffff:ffff:ffff:ffff:ffff:ffff
174ff2b:ad0::/28ff2b:adf:ffff:ffff:ffff:ffff:ffff:ffff
175ff2b:ae0::/28ff2b:aef:ffff:ffff:ffff:ffff:ffff:ffff
176ff2b:af0::/28ff2b:aff:ffff:ffff:ffff:ffff:ffff:ffff
177ff2b:b00::/28ff2b:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178ff2b:b10::/28ff2b:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179ff2b:b20::/28ff2b:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180ff2b:b30::/28ff2b:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181ff2b:b40::/28ff2b:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182ff2b:b50::/28ff2b:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183ff2b:b60::/28ff2b:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184ff2b:b70::/28ff2b:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185ff2b:b80::/28ff2b:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186ff2b:b90::/28ff2b:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187ff2b:ba0::/28ff2b:baf:ffff:ffff:ffff:ffff:ffff:ffff
188ff2b:bb0::/28ff2b:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189ff2b:bc0::/28ff2b:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190ff2b:bd0::/28ff2b:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191ff2b:be0::/28ff2b:bef:ffff:ffff:ffff:ffff:ffff:ffff
192ff2b:bf0::/28ff2b:bff:ffff:ffff:ffff:ffff:ffff:ffff
193ff2b:c00::/28ff2b:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194ff2b:c10::/28ff2b:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195ff2b:c20::/28ff2b:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196ff2b:c30::/28ff2b:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197ff2b:c40::/28ff2b:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198ff2b:c50::/28ff2b:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199ff2b:c60::/28ff2b:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200ff2b:c70::/28ff2b:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201ff2b:c80::/28ff2b:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202ff2b:c90::/28ff2b:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203ff2b:ca0::/28ff2b:caf:ffff:ffff:ffff:ffff:ffff:ffff
204ff2b:cb0::/28ff2b:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205ff2b:cc0::/28ff2b:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206ff2b:cd0::/28ff2b:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207ff2b:ce0::/28ff2b:cef:ffff:ffff:ffff:ffff:ffff:ffff
208ff2b:cf0::/28ff2b:cff:ffff:ffff:ffff:ffff:ffff:ffff
209ff2b:d00::/28ff2b:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210ff2b:d10::/28ff2b:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211ff2b:d20::/28ff2b:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212ff2b:d30::/28ff2b:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213ff2b:d40::/28ff2b:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214ff2b:d50::/28ff2b:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215ff2b:d60::/28ff2b:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216ff2b:d70::/28ff2b:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217ff2b:d80::/28ff2b:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218ff2b:d90::/28ff2b:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219ff2b:da0::/28ff2b:daf:ffff:ffff:ffff:ffff:ffff:ffff
220ff2b:db0::/28ff2b:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221ff2b:dc0::/28ff2b:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222ff2b:dd0::/28ff2b:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223ff2b:de0::/28ff2b:def:ffff:ffff:ffff:ffff:ffff:ffff
224ff2b:df0::/28ff2b:dff:ffff:ffff:ffff:ffff:ffff:ffff
225ff2b:e00::/28ff2b:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226ff2b:e10::/28ff2b:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227ff2b:e20::/28ff2b:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228ff2b:e30::/28ff2b:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229ff2b:e40::/28ff2b:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230ff2b:e50::/28ff2b:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231ff2b:e60::/28ff2b:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232ff2b:e70::/28ff2b:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233ff2b:e80::/28ff2b:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234ff2b:e90::/28ff2b:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235ff2b:ea0::/28ff2b:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236ff2b:eb0::/28ff2b:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237ff2b:ec0::/28ff2b:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238ff2b:ed0::/28ff2b:edf:ffff:ffff:ffff:ffff:ffff:ffff
239ff2b:ee0::/28ff2b:eef:ffff:ffff:ffff:ffff:ffff:ffff
240ff2b:ef0::/28ff2b:eff:ffff:ffff:ffff:ffff:ffff:ffff
241ff2b:f00::/28ff2b:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242ff2b:f10::/28ff2b:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243ff2b:f20::/28ff2b:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244ff2b:f30::/28ff2b:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245ff2b:f40::/28ff2b:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246ff2b:f50::/28ff2b:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247ff2b:f60::/28ff2b:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248ff2b:f70::/28ff2b:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249ff2b:f80::/28ff2b:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250ff2b:f90::/28ff2b:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251ff2b:fa0::/28ff2b:faf:ffff:ffff:ffff:ffff:ffff:ffff
252ff2b:fb0::/28ff2b:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253ff2b:fc0::/28ff2b:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254ff2b:fd0::/28ff2b:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255ff2b:fe0::/28ff2b:fef:ffff:ffff:ffff:ffff:ffff:ffff
256ff2b:ff0::/28ff2b: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.