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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
ff91::/16
First address
ff91::
Last address
ff91: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
ff91:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
1.9.f.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ff91::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1ff91::/24ff91:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ff91:100::/24ff91:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ff91:200::/24ff91:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ff91:300::/24ff91:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ff91:400::/24ff91:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ff91:500::/24ff91:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ff91:600::/24ff91:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ff91:700::/24ff91:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ff91:800::/24ff91:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ff91:900::/24ff91:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ff91:a00::/24ff91:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ff91:b00::/24ff91:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ff91:c00::/24ff91:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ff91:d00::/24ff91:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ff91:e00::/24ff91:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ff91:f00::/24ff91:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ff91:1000::/24ff91:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ff91:1100::/24ff91:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ff91:1200::/24ff91:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ff91:1300::/24ff91:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ff91:1400::/24ff91:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ff91:1500::/24ff91:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ff91:1600::/24ff91:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ff91:1700::/24ff91:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ff91:1800::/24ff91:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ff91:1900::/24ff91:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ff91:1a00::/24ff91:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ff91:1b00::/24ff91:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ff91:1c00::/24ff91:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ff91:1d00::/24ff91:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ff91:1e00::/24ff91:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ff91:1f00::/24ff91:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ff91:2000::/24ff91:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ff91:2100::/24ff91:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ff91:2200::/24ff91:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ff91:2300::/24ff91:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ff91:2400::/24ff91:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ff91:2500::/24ff91:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ff91:2600::/24ff91:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ff91:2700::/24ff91:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ff91:2800::/24ff91:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ff91:2900::/24ff91:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ff91:2a00::/24ff91:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ff91:2b00::/24ff91:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ff91:2c00::/24ff91:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ff91:2d00::/24ff91:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ff91:2e00::/24ff91:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ff91:2f00::/24ff91:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ff91:3000::/24ff91:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ff91:3100::/24ff91:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ff91:3200::/24ff91:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ff91:3300::/24ff91:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ff91:3400::/24ff91:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ff91:3500::/24ff91:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ff91:3600::/24ff91:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ff91:3700::/24ff91:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ff91:3800::/24ff91:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ff91:3900::/24ff91:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ff91:3a00::/24ff91:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ff91:3b00::/24ff91:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ff91:3c00::/24ff91:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ff91:3d00::/24ff91:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ff91:3e00::/24ff91:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ff91:3f00::/24ff91:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ff91:4000::/24ff91:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ff91:4100::/24ff91:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ff91:4200::/24ff91:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ff91:4300::/24ff91:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ff91:4400::/24ff91:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ff91:4500::/24ff91:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ff91:4600::/24ff91:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ff91:4700::/24ff91:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ff91:4800::/24ff91:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ff91:4900::/24ff91:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ff91:4a00::/24ff91:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ff91:4b00::/24ff91:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ff91:4c00::/24ff91:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ff91:4d00::/24ff91:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ff91:4e00::/24ff91:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ff91:4f00::/24ff91:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ff91:5000::/24ff91:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ff91:5100::/24ff91:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ff91:5200::/24ff91:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ff91:5300::/24ff91:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ff91:5400::/24ff91:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ff91:5500::/24ff91:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ff91:5600::/24ff91:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ff91:5700::/24ff91:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ff91:5800::/24ff91:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ff91:5900::/24ff91:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ff91:5a00::/24ff91:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ff91:5b00::/24ff91:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ff91:5c00::/24ff91:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ff91:5d00::/24ff91:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ff91:5e00::/24ff91:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ff91:5f00::/24ff91:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ff91:6000::/24ff91:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ff91:6100::/24ff91:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ff91:6200::/24ff91:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ff91:6300::/24ff91:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ff91:6400::/24ff91:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ff91:6500::/24ff91:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ff91:6600::/24ff91:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ff91:6700::/24ff91:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ff91:6800::/24ff91:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ff91:6900::/24ff91:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ff91:6a00::/24ff91:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ff91:6b00::/24ff91:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ff91:6c00::/24ff91:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ff91:6d00::/24ff91:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ff91:6e00::/24ff91:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ff91:6f00::/24ff91:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ff91:7000::/24ff91:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ff91:7100::/24ff91:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ff91:7200::/24ff91:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ff91:7300::/24ff91:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ff91:7400::/24ff91:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ff91:7500::/24ff91:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ff91:7600::/24ff91:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ff91:7700::/24ff91:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ff91:7800::/24ff91:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ff91:7900::/24ff91:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ff91:7a00::/24ff91:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ff91:7b00::/24ff91:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ff91:7c00::/24ff91:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ff91:7d00::/24ff91:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ff91:7e00::/24ff91:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ff91:7f00::/24ff91:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129ff91:8000::/24ff91:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130ff91:8100::/24ff91:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131ff91:8200::/24ff91:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132ff91:8300::/24ff91:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133ff91:8400::/24ff91:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134ff91:8500::/24ff91:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135ff91:8600::/24ff91:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136ff91:8700::/24ff91:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137ff91:8800::/24ff91:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138ff91:8900::/24ff91:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139ff91:8a00::/24ff91:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140ff91:8b00::/24ff91:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141ff91:8c00::/24ff91:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142ff91:8d00::/24ff91:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143ff91:8e00::/24ff91:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144ff91:8f00::/24ff91:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145ff91:9000::/24ff91:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146ff91:9100::/24ff91:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147ff91:9200::/24ff91:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148ff91:9300::/24ff91:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149ff91:9400::/24ff91:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150ff91:9500::/24ff91:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151ff91:9600::/24ff91:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152ff91:9700::/24ff91:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153ff91:9800::/24ff91:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154ff91:9900::/24ff91:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155ff91:9a00::/24ff91:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156ff91:9b00::/24ff91:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157ff91:9c00::/24ff91:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158ff91:9d00::/24ff91:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159ff91:9e00::/24ff91:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160ff91:9f00::/24ff91:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161ff91:a000::/24ff91:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162ff91:a100::/24ff91:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163ff91:a200::/24ff91:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164ff91:a300::/24ff91:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165ff91:a400::/24ff91:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166ff91:a500::/24ff91:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167ff91:a600::/24ff91:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168ff91:a700::/24ff91:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169ff91:a800::/24ff91:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170ff91:a900::/24ff91:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171ff91:aa00::/24ff91:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172ff91:ab00::/24ff91:abff:ffff:ffff:ffff:ffff:ffff:ffff
173ff91:ac00::/24ff91:acff:ffff:ffff:ffff:ffff:ffff:ffff
174ff91:ad00::/24ff91:adff:ffff:ffff:ffff:ffff:ffff:ffff
175ff91:ae00::/24ff91:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176ff91:af00::/24ff91:afff:ffff:ffff:ffff:ffff:ffff:ffff
177ff91:b000::/24ff91:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178ff91:b100::/24ff91:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179ff91:b200::/24ff91:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180ff91:b300::/24ff91:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181ff91:b400::/24ff91:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182ff91:b500::/24ff91:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183ff91:b600::/24ff91:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184ff91:b700::/24ff91:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185ff91:b800::/24ff91:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186ff91:b900::/24ff91:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187ff91:ba00::/24ff91:baff:ffff:ffff:ffff:ffff:ffff:ffff
188ff91:bb00::/24ff91:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189ff91:bc00::/24ff91:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190ff91:bd00::/24ff91:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191ff91:be00::/24ff91:beff:ffff:ffff:ffff:ffff:ffff:ffff
192ff91:bf00::/24ff91:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193ff91:c000::/24ff91:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194ff91:c100::/24ff91:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195ff91:c200::/24ff91:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196ff91:c300::/24ff91:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197ff91:c400::/24ff91:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198ff91:c500::/24ff91:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199ff91:c600::/24ff91:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200ff91:c700::/24ff91:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201ff91:c800::/24ff91:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202ff91:c900::/24ff91:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203ff91:ca00::/24ff91:caff:ffff:ffff:ffff:ffff:ffff:ffff
204ff91:cb00::/24ff91:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205ff91:cc00::/24ff91:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206ff91:cd00::/24ff91:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207ff91:ce00::/24ff91:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208ff91:cf00::/24ff91:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209ff91:d000::/24ff91:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210ff91:d100::/24ff91:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211ff91:d200::/24ff91:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212ff91:d300::/24ff91:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213ff91:d400::/24ff91:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214ff91:d500::/24ff91:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215ff91:d600::/24ff91:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216ff91:d700::/24ff91:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217ff91:d800::/24ff91:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218ff91:d900::/24ff91:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219ff91:da00::/24ff91:daff:ffff:ffff:ffff:ffff:ffff:ffff
220ff91:db00::/24ff91:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221ff91:dc00::/24ff91:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222ff91:dd00::/24ff91:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223ff91:de00::/24ff91:deff:ffff:ffff:ffff:ffff:ffff:ffff
224ff91:df00::/24ff91:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225ff91:e000::/24ff91:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226ff91:e100::/24ff91:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227ff91:e200::/24ff91:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228ff91:e300::/24ff91:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229ff91:e400::/24ff91:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230ff91:e500::/24ff91:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231ff91:e600::/24ff91:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232ff91:e700::/24ff91:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233ff91:e800::/24ff91:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234ff91:e900::/24ff91:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235ff91:ea00::/24ff91:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236ff91:eb00::/24ff91:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237ff91:ec00::/24ff91:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238ff91:ed00::/24ff91:edff:ffff:ffff:ffff:ffff:ffff:ffff
239ff91:ee00::/24ff91:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240ff91:ef00::/24ff91:efff:ffff:ffff:ffff:ffff:ffff:ffff
241ff91:f000::/24ff91:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242ff91:f100::/24ff91:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243ff91:f200::/24ff91:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244ff91:f300::/24ff91:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245ff91:f400::/24ff91:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246ff91:f500::/24ff91:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247ff91:f600::/24ff91:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248ff91:f700::/24ff91:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249ff91:f800::/24ff91:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250ff91:f900::/24ff91:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251ff91:fa00::/24ff91:faff:ffff:ffff:ffff:ffff:ffff:ffff
252ff91:fb00::/24ff91:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253ff91:fc00::/24ff91:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254ff91:fd00::/24ff91:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255ff91:fe00::/24ff91:feff:ffff:ffff:ffff:ffff:ffff:ffff
256ff91:ff00::/24ff91:ffff: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.