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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
fca9::/16
First address
fca9::
Last address
fca9: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
fca9:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
9.a.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)

fca9::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fca9::/24fca9:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fca9:100::/24fca9:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fca9:200::/24fca9:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fca9:300::/24fca9:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fca9:400::/24fca9:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fca9:500::/24fca9:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fca9:600::/24fca9:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fca9:700::/24fca9:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fca9:800::/24fca9:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fca9:900::/24fca9:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fca9:a00::/24fca9:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fca9:b00::/24fca9:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fca9:c00::/24fca9:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fca9:d00::/24fca9:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fca9:e00::/24fca9:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fca9:f00::/24fca9:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fca9:1000::/24fca9:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fca9:1100::/24fca9:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fca9:1200::/24fca9:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fca9:1300::/24fca9:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fca9:1400::/24fca9:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fca9:1500::/24fca9:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fca9:1600::/24fca9:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fca9:1700::/24fca9:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fca9:1800::/24fca9:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fca9:1900::/24fca9:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fca9:1a00::/24fca9:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fca9:1b00::/24fca9:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fca9:1c00::/24fca9:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fca9:1d00::/24fca9:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fca9:1e00::/24fca9:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fca9:1f00::/24fca9:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fca9:2000::/24fca9:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fca9:2100::/24fca9:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fca9:2200::/24fca9:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fca9:2300::/24fca9:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fca9:2400::/24fca9:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fca9:2500::/24fca9:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fca9:2600::/24fca9:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fca9:2700::/24fca9:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fca9:2800::/24fca9:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fca9:2900::/24fca9:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fca9:2a00::/24fca9:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fca9:2b00::/24fca9:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fca9:2c00::/24fca9:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fca9:2d00::/24fca9:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fca9:2e00::/24fca9:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fca9:2f00::/24fca9:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fca9:3000::/24fca9:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fca9:3100::/24fca9:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fca9:3200::/24fca9:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fca9:3300::/24fca9:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fca9:3400::/24fca9:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fca9:3500::/24fca9:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fca9:3600::/24fca9:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fca9:3700::/24fca9:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fca9:3800::/24fca9:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fca9:3900::/24fca9:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fca9:3a00::/24fca9:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fca9:3b00::/24fca9:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fca9:3c00::/24fca9:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fca9:3d00::/24fca9:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fca9:3e00::/24fca9:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fca9:3f00::/24fca9:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fca9:4000::/24fca9:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fca9:4100::/24fca9:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fca9:4200::/24fca9:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fca9:4300::/24fca9:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fca9:4400::/24fca9:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fca9:4500::/24fca9:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fca9:4600::/24fca9:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fca9:4700::/24fca9:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fca9:4800::/24fca9:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fca9:4900::/24fca9:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fca9:4a00::/24fca9:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fca9:4b00::/24fca9:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fca9:4c00::/24fca9:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fca9:4d00::/24fca9:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fca9:4e00::/24fca9:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fca9:4f00::/24fca9:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fca9:5000::/24fca9:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fca9:5100::/24fca9:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fca9:5200::/24fca9:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fca9:5300::/24fca9:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fca9:5400::/24fca9:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fca9:5500::/24fca9:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fca9:5600::/24fca9:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fca9:5700::/24fca9:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fca9:5800::/24fca9:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fca9:5900::/24fca9:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fca9:5a00::/24fca9:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fca9:5b00::/24fca9:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fca9:5c00::/24fca9:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fca9:5d00::/24fca9:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fca9:5e00::/24fca9:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fca9:5f00::/24fca9:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fca9:6000::/24fca9:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fca9:6100::/24fca9:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fca9:6200::/24fca9:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fca9:6300::/24fca9:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fca9:6400::/24fca9:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fca9:6500::/24fca9:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fca9:6600::/24fca9:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fca9:6700::/24fca9:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fca9:6800::/24fca9:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fca9:6900::/24fca9:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fca9:6a00::/24fca9:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fca9:6b00::/24fca9:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fca9:6c00::/24fca9:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fca9:6d00::/24fca9:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fca9:6e00::/24fca9:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fca9:6f00::/24fca9:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fca9:7000::/24fca9:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fca9:7100::/24fca9:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fca9:7200::/24fca9:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fca9:7300::/24fca9:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fca9:7400::/24fca9:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fca9:7500::/24fca9:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fca9:7600::/24fca9:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fca9:7700::/24fca9:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fca9:7800::/24fca9:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fca9:7900::/24fca9:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fca9:7a00::/24fca9:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fca9:7b00::/24fca9:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fca9:7c00::/24fca9:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fca9:7d00::/24fca9:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fca9:7e00::/24fca9:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fca9:7f00::/24fca9:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fca9:8000::/24fca9:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fca9:8100::/24fca9:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fca9:8200::/24fca9:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fca9:8300::/24fca9:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fca9:8400::/24fca9:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fca9:8500::/24fca9:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fca9:8600::/24fca9:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fca9:8700::/24fca9:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fca9:8800::/24fca9:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fca9:8900::/24fca9:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fca9:8a00::/24fca9:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fca9:8b00::/24fca9:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fca9:8c00::/24fca9:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fca9:8d00::/24fca9:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fca9:8e00::/24fca9:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fca9:8f00::/24fca9:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fca9:9000::/24fca9:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fca9:9100::/24fca9:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fca9:9200::/24fca9:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fca9:9300::/24fca9:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fca9:9400::/24fca9:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fca9:9500::/24fca9:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fca9:9600::/24fca9:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fca9:9700::/24fca9:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fca9:9800::/24fca9:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fca9:9900::/24fca9:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fca9:9a00::/24fca9:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fca9:9b00::/24fca9:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fca9:9c00::/24fca9:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fca9:9d00::/24fca9:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fca9:9e00::/24fca9:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fca9:9f00::/24fca9:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fca9:a000::/24fca9:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fca9:a100::/24fca9:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fca9:a200::/24fca9:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fca9:a300::/24fca9:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fca9:a400::/24fca9:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fca9:a500::/24fca9:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fca9:a600::/24fca9:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fca9:a700::/24fca9:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fca9:a800::/24fca9:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fca9:a900::/24fca9:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fca9:aa00::/24fca9:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fca9:ab00::/24fca9:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fca9:ac00::/24fca9:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fca9:ad00::/24fca9:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fca9:ae00::/24fca9:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fca9:af00::/24fca9:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fca9:b000::/24fca9:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fca9:b100::/24fca9:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fca9:b200::/24fca9:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fca9:b300::/24fca9:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fca9:b400::/24fca9:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fca9:b500::/24fca9:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fca9:b600::/24fca9:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fca9:b700::/24fca9:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fca9:b800::/24fca9:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fca9:b900::/24fca9:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fca9:ba00::/24fca9:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fca9:bb00::/24fca9:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fca9:bc00::/24fca9:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fca9:bd00::/24fca9:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fca9:be00::/24fca9:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fca9:bf00::/24fca9:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fca9:c000::/24fca9:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fca9:c100::/24fca9:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fca9:c200::/24fca9:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fca9:c300::/24fca9:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fca9:c400::/24fca9:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fca9:c500::/24fca9:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fca9:c600::/24fca9:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fca9:c700::/24fca9:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fca9:c800::/24fca9:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fca9:c900::/24fca9:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fca9:ca00::/24fca9:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fca9:cb00::/24fca9:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fca9:cc00::/24fca9:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fca9:cd00::/24fca9:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fca9:ce00::/24fca9:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fca9:cf00::/24fca9:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fca9:d000::/24fca9:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fca9:d100::/24fca9:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fca9:d200::/24fca9:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fca9:d300::/24fca9:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fca9:d400::/24fca9:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fca9:d500::/24fca9:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fca9:d600::/24fca9:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fca9:d700::/24fca9:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fca9:d800::/24fca9:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fca9:d900::/24fca9:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fca9:da00::/24fca9:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fca9:db00::/24fca9:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fca9:dc00::/24fca9:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fca9:dd00::/24fca9:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fca9:de00::/24fca9:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fca9:df00::/24fca9:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fca9:e000::/24fca9:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fca9:e100::/24fca9:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fca9:e200::/24fca9:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fca9:e300::/24fca9:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fca9:e400::/24fca9:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fca9:e500::/24fca9:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fca9:e600::/24fca9:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fca9:e700::/24fca9:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fca9:e800::/24fca9:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fca9:e900::/24fca9:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fca9:ea00::/24fca9:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fca9:eb00::/24fca9:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fca9:ec00::/24fca9:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fca9:ed00::/24fca9:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fca9:ee00::/24fca9:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fca9:ef00::/24fca9:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fca9:f000::/24fca9:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fca9:f100::/24fca9:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fca9:f200::/24fca9:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fca9:f300::/24fca9:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fca9:f400::/24fca9:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fca9:f500::/24fca9:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fca9:f600::/24fca9:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fca9:f700::/24fca9:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fca9:f800::/24fca9:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fca9:f900::/24fca9:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fca9:fa00::/24fca9:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fca9:fb00::/24fca9:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fca9:fc00::/24fca9:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fca9:fd00::/24fca9:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fca9:fe00::/24fca9:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fca9:ff00::/24fca9: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.