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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
ff9b::/16
First address
ff9b::
Last address
ff9b: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
ff9b:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
b.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)

ff9b::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1ff9b::/24ff9b:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ff9b:100::/24ff9b:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ff9b:200::/24ff9b:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ff9b:300::/24ff9b:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ff9b:400::/24ff9b:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ff9b:500::/24ff9b:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ff9b:600::/24ff9b:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ff9b:700::/24ff9b:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ff9b:800::/24ff9b:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ff9b:900::/24ff9b:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ff9b:a00::/24ff9b:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ff9b:b00::/24ff9b:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ff9b:c00::/24ff9b:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ff9b:d00::/24ff9b:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ff9b:e00::/24ff9b:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ff9b:f00::/24ff9b:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ff9b:1000::/24ff9b:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ff9b:1100::/24ff9b:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ff9b:1200::/24ff9b:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ff9b:1300::/24ff9b:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ff9b:1400::/24ff9b:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ff9b:1500::/24ff9b:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ff9b:1600::/24ff9b:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ff9b:1700::/24ff9b:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ff9b:1800::/24ff9b:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ff9b:1900::/24ff9b:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ff9b:1a00::/24ff9b:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ff9b:1b00::/24ff9b:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ff9b:1c00::/24ff9b:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ff9b:1d00::/24ff9b:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ff9b:1e00::/24ff9b:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ff9b:1f00::/24ff9b:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ff9b:2000::/24ff9b:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ff9b:2100::/24ff9b:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ff9b:2200::/24ff9b:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ff9b:2300::/24ff9b:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ff9b:2400::/24ff9b:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ff9b:2500::/24ff9b:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ff9b:2600::/24ff9b:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ff9b:2700::/24ff9b:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ff9b:2800::/24ff9b:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ff9b:2900::/24ff9b:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ff9b:2a00::/24ff9b:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ff9b:2b00::/24ff9b:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ff9b:2c00::/24ff9b:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ff9b:2d00::/24ff9b:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ff9b:2e00::/24ff9b:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ff9b:2f00::/24ff9b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ff9b:3000::/24ff9b:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ff9b:3100::/24ff9b:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ff9b:3200::/24ff9b:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ff9b:3300::/24ff9b:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ff9b:3400::/24ff9b:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ff9b:3500::/24ff9b:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ff9b:3600::/24ff9b:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ff9b:3700::/24ff9b:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ff9b:3800::/24ff9b:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ff9b:3900::/24ff9b:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ff9b:3a00::/24ff9b:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ff9b:3b00::/24ff9b:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ff9b:3c00::/24ff9b:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ff9b:3d00::/24ff9b:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ff9b:3e00::/24ff9b:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ff9b:3f00::/24ff9b:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ff9b:4000::/24ff9b:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ff9b:4100::/24ff9b:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ff9b:4200::/24ff9b:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ff9b:4300::/24ff9b:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ff9b:4400::/24ff9b:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ff9b:4500::/24ff9b:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ff9b:4600::/24ff9b:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ff9b:4700::/24ff9b:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ff9b:4800::/24ff9b:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ff9b:4900::/24ff9b:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ff9b:4a00::/24ff9b:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ff9b:4b00::/24ff9b:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ff9b:4c00::/24ff9b:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ff9b:4d00::/24ff9b:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ff9b:4e00::/24ff9b:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ff9b:4f00::/24ff9b:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ff9b:5000::/24ff9b:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ff9b:5100::/24ff9b:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ff9b:5200::/24ff9b:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ff9b:5300::/24ff9b:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ff9b:5400::/24ff9b:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ff9b:5500::/24ff9b:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ff9b:5600::/24ff9b:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ff9b:5700::/24ff9b:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ff9b:5800::/24ff9b:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ff9b:5900::/24ff9b:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ff9b:5a00::/24ff9b:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ff9b:5b00::/24ff9b:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ff9b:5c00::/24ff9b:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ff9b:5d00::/24ff9b:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ff9b:5e00::/24ff9b:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ff9b:5f00::/24ff9b:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ff9b:6000::/24ff9b:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ff9b:6100::/24ff9b:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ff9b:6200::/24ff9b:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ff9b:6300::/24ff9b:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ff9b:6400::/24ff9b:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ff9b:6500::/24ff9b:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ff9b:6600::/24ff9b:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ff9b:6700::/24ff9b:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ff9b:6800::/24ff9b:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ff9b:6900::/24ff9b:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ff9b:6a00::/24ff9b:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ff9b:6b00::/24ff9b:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ff9b:6c00::/24ff9b:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ff9b:6d00::/24ff9b:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ff9b:6e00::/24ff9b:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ff9b:6f00::/24ff9b:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ff9b:7000::/24ff9b:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ff9b:7100::/24ff9b:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ff9b:7200::/24ff9b:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ff9b:7300::/24ff9b:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ff9b:7400::/24ff9b:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ff9b:7500::/24ff9b:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ff9b:7600::/24ff9b:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ff9b:7700::/24ff9b:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ff9b:7800::/24ff9b:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ff9b:7900::/24ff9b:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ff9b:7a00::/24ff9b:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ff9b:7b00::/24ff9b:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ff9b:7c00::/24ff9b:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ff9b:7d00::/24ff9b:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ff9b:7e00::/24ff9b:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ff9b:7f00::/24ff9b:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129ff9b:8000::/24ff9b:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130ff9b:8100::/24ff9b:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131ff9b:8200::/24ff9b:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132ff9b:8300::/24ff9b:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133ff9b:8400::/24ff9b:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134ff9b:8500::/24ff9b:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135ff9b:8600::/24ff9b:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136ff9b:8700::/24ff9b:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137ff9b:8800::/24ff9b:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138ff9b:8900::/24ff9b:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139ff9b:8a00::/24ff9b:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140ff9b:8b00::/24ff9b:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141ff9b:8c00::/24ff9b:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142ff9b:8d00::/24ff9b:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143ff9b:8e00::/24ff9b:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144ff9b:8f00::/24ff9b:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145ff9b:9000::/24ff9b:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146ff9b:9100::/24ff9b:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147ff9b:9200::/24ff9b:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148ff9b:9300::/24ff9b:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149ff9b:9400::/24ff9b:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150ff9b:9500::/24ff9b:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151ff9b:9600::/24ff9b:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152ff9b:9700::/24ff9b:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153ff9b:9800::/24ff9b:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154ff9b:9900::/24ff9b:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155ff9b:9a00::/24ff9b:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156ff9b:9b00::/24ff9b:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157ff9b:9c00::/24ff9b:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158ff9b:9d00::/24ff9b:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159ff9b:9e00::/24ff9b:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160ff9b:9f00::/24ff9b:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161ff9b:a000::/24ff9b:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162ff9b:a100::/24ff9b:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163ff9b:a200::/24ff9b:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164ff9b:a300::/24ff9b:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165ff9b:a400::/24ff9b:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166ff9b:a500::/24ff9b:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167ff9b:a600::/24ff9b:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168ff9b:a700::/24ff9b:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169ff9b:a800::/24ff9b:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170ff9b:a900::/24ff9b:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171ff9b:aa00::/24ff9b:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172ff9b:ab00::/24ff9b:abff:ffff:ffff:ffff:ffff:ffff:ffff
173ff9b:ac00::/24ff9b:acff:ffff:ffff:ffff:ffff:ffff:ffff
174ff9b:ad00::/24ff9b:adff:ffff:ffff:ffff:ffff:ffff:ffff
175ff9b:ae00::/24ff9b:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176ff9b:af00::/24ff9b:afff:ffff:ffff:ffff:ffff:ffff:ffff
177ff9b:b000::/24ff9b:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178ff9b:b100::/24ff9b:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179ff9b:b200::/24ff9b:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180ff9b:b300::/24ff9b:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181ff9b:b400::/24ff9b:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182ff9b:b500::/24ff9b:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183ff9b:b600::/24ff9b:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184ff9b:b700::/24ff9b:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185ff9b:b800::/24ff9b:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186ff9b:b900::/24ff9b:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187ff9b:ba00::/24ff9b:baff:ffff:ffff:ffff:ffff:ffff:ffff
188ff9b:bb00::/24ff9b:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189ff9b:bc00::/24ff9b:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190ff9b:bd00::/24ff9b:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191ff9b:be00::/24ff9b:beff:ffff:ffff:ffff:ffff:ffff:ffff
192ff9b:bf00::/24ff9b:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193ff9b:c000::/24ff9b:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194ff9b:c100::/24ff9b:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195ff9b:c200::/24ff9b:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196ff9b:c300::/24ff9b:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197ff9b:c400::/24ff9b:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198ff9b:c500::/24ff9b:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199ff9b:c600::/24ff9b:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200ff9b:c700::/24ff9b:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201ff9b:c800::/24ff9b:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202ff9b:c900::/24ff9b:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203ff9b:ca00::/24ff9b:caff:ffff:ffff:ffff:ffff:ffff:ffff
204ff9b:cb00::/24ff9b:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205ff9b:cc00::/24ff9b:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206ff9b:cd00::/24ff9b:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207ff9b:ce00::/24ff9b:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208ff9b:cf00::/24ff9b:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209ff9b:d000::/24ff9b:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210ff9b:d100::/24ff9b:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211ff9b:d200::/24ff9b:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212ff9b:d300::/24ff9b:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213ff9b:d400::/24ff9b:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214ff9b:d500::/24ff9b:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215ff9b:d600::/24ff9b:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216ff9b:d700::/24ff9b:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217ff9b:d800::/24ff9b:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218ff9b:d900::/24ff9b:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219ff9b:da00::/24ff9b:daff:ffff:ffff:ffff:ffff:ffff:ffff
220ff9b:db00::/24ff9b:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221ff9b:dc00::/24ff9b:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222ff9b:dd00::/24ff9b:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223ff9b:de00::/24ff9b:deff:ffff:ffff:ffff:ffff:ffff:ffff
224ff9b:df00::/24ff9b:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225ff9b:e000::/24ff9b:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226ff9b:e100::/24ff9b:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227ff9b:e200::/24ff9b:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228ff9b:e300::/24ff9b:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229ff9b:e400::/24ff9b:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230ff9b:e500::/24ff9b:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231ff9b:e600::/24ff9b:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232ff9b:e700::/24ff9b:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233ff9b:e800::/24ff9b:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234ff9b:e900::/24ff9b:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235ff9b:ea00::/24ff9b:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236ff9b:eb00::/24ff9b:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237ff9b:ec00::/24ff9b:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238ff9b:ed00::/24ff9b:edff:ffff:ffff:ffff:ffff:ffff:ffff
239ff9b:ee00::/24ff9b:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240ff9b:ef00::/24ff9b:efff:ffff:ffff:ffff:ffff:ffff:ffff
241ff9b:f000::/24ff9b:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242ff9b:f100::/24ff9b:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243ff9b:f200::/24ff9b:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244ff9b:f300::/24ff9b:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245ff9b:f400::/24ff9b:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246ff9b:f500::/24ff9b:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247ff9b:f600::/24ff9b:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248ff9b:f700::/24ff9b:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249ff9b:f800::/24ff9b:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250ff9b:f900::/24ff9b:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251ff9b:fa00::/24ff9b:faff:ffff:ffff:ffff:ffff:ffff:ffff
252ff9b:fb00::/24ff9b:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253ff9b:fc00::/24ff9b:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254ff9b:fd00::/24ff9b:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255ff9b:fe00::/24ff9b:feff:ffff:ffff:ffff:ffff:ffff:ffff
256ff9b:ff00::/24ff9b: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.