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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
fcd0::/16
First address
fcd0::
Last address
fcd0: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
fcd0:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
0.d.c.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fcd0::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fcd0::/24fcd0:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fcd0:100::/24fcd0:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fcd0:200::/24fcd0:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fcd0:300::/24fcd0:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fcd0:400::/24fcd0:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fcd0:500::/24fcd0:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fcd0:600::/24fcd0:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fcd0:700::/24fcd0:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fcd0:800::/24fcd0:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fcd0:900::/24fcd0:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fcd0:a00::/24fcd0:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fcd0:b00::/24fcd0:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fcd0:c00::/24fcd0:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fcd0:d00::/24fcd0:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fcd0:e00::/24fcd0:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fcd0:f00::/24fcd0:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fcd0:1000::/24fcd0:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fcd0:1100::/24fcd0:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fcd0:1200::/24fcd0:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fcd0:1300::/24fcd0:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fcd0:1400::/24fcd0:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fcd0:1500::/24fcd0:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fcd0:1600::/24fcd0:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fcd0:1700::/24fcd0:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fcd0:1800::/24fcd0:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fcd0:1900::/24fcd0:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fcd0:1a00::/24fcd0:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fcd0:1b00::/24fcd0:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fcd0:1c00::/24fcd0:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fcd0:1d00::/24fcd0:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fcd0:1e00::/24fcd0:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fcd0:1f00::/24fcd0:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fcd0:2000::/24fcd0:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fcd0:2100::/24fcd0:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fcd0:2200::/24fcd0:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fcd0:2300::/24fcd0:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fcd0:2400::/24fcd0:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fcd0:2500::/24fcd0:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fcd0:2600::/24fcd0:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fcd0:2700::/24fcd0:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fcd0:2800::/24fcd0:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fcd0:2900::/24fcd0:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fcd0:2a00::/24fcd0:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fcd0:2b00::/24fcd0:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fcd0:2c00::/24fcd0:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fcd0:2d00::/24fcd0:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fcd0:2e00::/24fcd0:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fcd0:2f00::/24fcd0:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fcd0:3000::/24fcd0:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fcd0:3100::/24fcd0:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fcd0:3200::/24fcd0:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fcd0:3300::/24fcd0:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fcd0:3400::/24fcd0:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fcd0:3500::/24fcd0:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fcd0:3600::/24fcd0:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fcd0:3700::/24fcd0:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fcd0:3800::/24fcd0:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fcd0:3900::/24fcd0:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fcd0:3a00::/24fcd0:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fcd0:3b00::/24fcd0:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fcd0:3c00::/24fcd0:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fcd0:3d00::/24fcd0:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fcd0:3e00::/24fcd0:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fcd0:3f00::/24fcd0:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fcd0:4000::/24fcd0:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fcd0:4100::/24fcd0:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fcd0:4200::/24fcd0:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fcd0:4300::/24fcd0:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fcd0:4400::/24fcd0:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fcd0:4500::/24fcd0:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fcd0:4600::/24fcd0:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fcd0:4700::/24fcd0:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fcd0:4800::/24fcd0:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fcd0:4900::/24fcd0:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fcd0:4a00::/24fcd0:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fcd0:4b00::/24fcd0:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fcd0:4c00::/24fcd0:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fcd0:4d00::/24fcd0:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fcd0:4e00::/24fcd0:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fcd0:4f00::/24fcd0:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fcd0:5000::/24fcd0:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fcd0:5100::/24fcd0:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fcd0:5200::/24fcd0:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fcd0:5300::/24fcd0:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fcd0:5400::/24fcd0:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fcd0:5500::/24fcd0:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fcd0:5600::/24fcd0:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fcd0:5700::/24fcd0:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fcd0:5800::/24fcd0:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fcd0:5900::/24fcd0:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fcd0:5a00::/24fcd0:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fcd0:5b00::/24fcd0:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fcd0:5c00::/24fcd0:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fcd0:5d00::/24fcd0:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fcd0:5e00::/24fcd0:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fcd0:5f00::/24fcd0:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fcd0:6000::/24fcd0:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fcd0:6100::/24fcd0:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fcd0:6200::/24fcd0:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fcd0:6300::/24fcd0:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fcd0:6400::/24fcd0:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fcd0:6500::/24fcd0:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fcd0:6600::/24fcd0:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fcd0:6700::/24fcd0:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fcd0:6800::/24fcd0:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fcd0:6900::/24fcd0:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fcd0:6a00::/24fcd0:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fcd0:6b00::/24fcd0:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fcd0:6c00::/24fcd0:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fcd0:6d00::/24fcd0:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fcd0:6e00::/24fcd0:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fcd0:6f00::/24fcd0:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fcd0:7000::/24fcd0:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fcd0:7100::/24fcd0:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fcd0:7200::/24fcd0:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fcd0:7300::/24fcd0:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fcd0:7400::/24fcd0:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fcd0:7500::/24fcd0:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fcd0:7600::/24fcd0:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fcd0:7700::/24fcd0:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fcd0:7800::/24fcd0:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fcd0:7900::/24fcd0:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fcd0:7a00::/24fcd0:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fcd0:7b00::/24fcd0:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fcd0:7c00::/24fcd0:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fcd0:7d00::/24fcd0:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fcd0:7e00::/24fcd0:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fcd0:7f00::/24fcd0:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fcd0:8000::/24fcd0:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fcd0:8100::/24fcd0:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fcd0:8200::/24fcd0:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fcd0:8300::/24fcd0:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fcd0:8400::/24fcd0:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fcd0:8500::/24fcd0:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fcd0:8600::/24fcd0:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fcd0:8700::/24fcd0:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fcd0:8800::/24fcd0:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fcd0:8900::/24fcd0:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fcd0:8a00::/24fcd0:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fcd0:8b00::/24fcd0:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fcd0:8c00::/24fcd0:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fcd0:8d00::/24fcd0:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fcd0:8e00::/24fcd0:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fcd0:8f00::/24fcd0:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fcd0:9000::/24fcd0:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fcd0:9100::/24fcd0:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fcd0:9200::/24fcd0:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fcd0:9300::/24fcd0:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fcd0:9400::/24fcd0:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fcd0:9500::/24fcd0:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fcd0:9600::/24fcd0:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fcd0:9700::/24fcd0:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fcd0:9800::/24fcd0:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fcd0:9900::/24fcd0:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fcd0:9a00::/24fcd0:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fcd0:9b00::/24fcd0:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fcd0:9c00::/24fcd0:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fcd0:9d00::/24fcd0:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fcd0:9e00::/24fcd0:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fcd0:9f00::/24fcd0:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fcd0:a000::/24fcd0:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fcd0:a100::/24fcd0:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fcd0:a200::/24fcd0:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fcd0:a300::/24fcd0:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fcd0:a400::/24fcd0:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fcd0:a500::/24fcd0:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fcd0:a600::/24fcd0:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fcd0:a700::/24fcd0:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fcd0:a800::/24fcd0:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fcd0:a900::/24fcd0:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fcd0:aa00::/24fcd0:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fcd0:ab00::/24fcd0:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fcd0:ac00::/24fcd0:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fcd0:ad00::/24fcd0:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fcd0:ae00::/24fcd0:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fcd0:af00::/24fcd0:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fcd0:b000::/24fcd0:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fcd0:b100::/24fcd0:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fcd0:b200::/24fcd0:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fcd0:b300::/24fcd0:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fcd0:b400::/24fcd0:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fcd0:b500::/24fcd0:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fcd0:b600::/24fcd0:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fcd0:b700::/24fcd0:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fcd0:b800::/24fcd0:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fcd0:b900::/24fcd0:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fcd0:ba00::/24fcd0:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fcd0:bb00::/24fcd0:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fcd0:bc00::/24fcd0:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fcd0:bd00::/24fcd0:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fcd0:be00::/24fcd0:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fcd0:bf00::/24fcd0:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fcd0:c000::/24fcd0:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fcd0:c100::/24fcd0:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fcd0:c200::/24fcd0:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fcd0:c300::/24fcd0:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fcd0:c400::/24fcd0:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fcd0:c500::/24fcd0:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fcd0:c600::/24fcd0:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fcd0:c700::/24fcd0:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fcd0:c800::/24fcd0:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fcd0:c900::/24fcd0:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fcd0:ca00::/24fcd0:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fcd0:cb00::/24fcd0:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fcd0:cc00::/24fcd0:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fcd0:cd00::/24fcd0:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fcd0:ce00::/24fcd0:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fcd0:cf00::/24fcd0:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fcd0:d000::/24fcd0:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fcd0:d100::/24fcd0:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fcd0:d200::/24fcd0:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fcd0:d300::/24fcd0:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fcd0:d400::/24fcd0:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fcd0:d500::/24fcd0:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fcd0:d600::/24fcd0:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fcd0:d700::/24fcd0:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fcd0:d800::/24fcd0:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fcd0:d900::/24fcd0:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fcd0:da00::/24fcd0:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fcd0:db00::/24fcd0:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fcd0:dc00::/24fcd0:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fcd0:dd00::/24fcd0:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fcd0:de00::/24fcd0:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fcd0:df00::/24fcd0:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fcd0:e000::/24fcd0:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fcd0:e100::/24fcd0:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fcd0:e200::/24fcd0:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fcd0:e300::/24fcd0:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fcd0:e400::/24fcd0:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fcd0:e500::/24fcd0:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fcd0:e600::/24fcd0:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fcd0:e700::/24fcd0:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fcd0:e800::/24fcd0:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fcd0:e900::/24fcd0:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fcd0:ea00::/24fcd0:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fcd0:eb00::/24fcd0:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fcd0:ec00::/24fcd0:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fcd0:ed00::/24fcd0:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fcd0:ee00::/24fcd0:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fcd0:ef00::/24fcd0:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fcd0:f000::/24fcd0:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fcd0:f100::/24fcd0:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fcd0:f200::/24fcd0:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fcd0:f300::/24fcd0:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fcd0:f400::/24fcd0:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fcd0:f500::/24fcd0:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fcd0:f600::/24fcd0:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fcd0:f700::/24fcd0:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fcd0:f800::/24fcd0:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fcd0:f900::/24fcd0:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fcd0:fa00::/24fcd0:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fcd0:fb00::/24fcd0:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fcd0:fc00::/24fcd0:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fcd0:fd00::/24fcd0:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fcd0:fe00::/24fcd0:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fcd0:ff00::/24fcd0: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.