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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
fca4::/16
First address
fca4::
Last address
fca4: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
fca4:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
4.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)

fca4::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fca4::/24fca4:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fca4:100::/24fca4:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fca4:200::/24fca4:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fca4:300::/24fca4:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fca4:400::/24fca4:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fca4:500::/24fca4:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fca4:600::/24fca4:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fca4:700::/24fca4:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fca4:800::/24fca4:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fca4:900::/24fca4:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fca4:a00::/24fca4:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fca4:b00::/24fca4:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fca4:c00::/24fca4:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fca4:d00::/24fca4:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fca4:e00::/24fca4:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fca4:f00::/24fca4:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fca4:1000::/24fca4:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fca4:1100::/24fca4:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fca4:1200::/24fca4:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fca4:1300::/24fca4:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fca4:1400::/24fca4:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fca4:1500::/24fca4:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fca4:1600::/24fca4:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fca4:1700::/24fca4:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fca4:1800::/24fca4:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fca4:1900::/24fca4:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fca4:1a00::/24fca4:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fca4:1b00::/24fca4:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fca4:1c00::/24fca4:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fca4:1d00::/24fca4:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fca4:1e00::/24fca4:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fca4:1f00::/24fca4:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fca4:2000::/24fca4:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fca4:2100::/24fca4:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fca4:2200::/24fca4:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fca4:2300::/24fca4:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fca4:2400::/24fca4:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fca4:2500::/24fca4:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fca4:2600::/24fca4:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fca4:2700::/24fca4:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fca4:2800::/24fca4:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fca4:2900::/24fca4:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fca4:2a00::/24fca4:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fca4:2b00::/24fca4:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fca4:2c00::/24fca4:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fca4:2d00::/24fca4:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fca4:2e00::/24fca4:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fca4:2f00::/24fca4:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fca4:3000::/24fca4:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fca4:3100::/24fca4:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fca4:3200::/24fca4:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fca4:3300::/24fca4:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fca4:3400::/24fca4:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fca4:3500::/24fca4:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fca4:3600::/24fca4:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fca4:3700::/24fca4:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fca4:3800::/24fca4:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fca4:3900::/24fca4:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fca4:3a00::/24fca4:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fca4:3b00::/24fca4:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fca4:3c00::/24fca4:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fca4:3d00::/24fca4:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fca4:3e00::/24fca4:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fca4:3f00::/24fca4:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fca4:4000::/24fca4:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fca4:4100::/24fca4:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fca4:4200::/24fca4:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fca4:4300::/24fca4:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fca4:4400::/24fca4:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fca4:4500::/24fca4:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fca4:4600::/24fca4:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fca4:4700::/24fca4:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fca4:4800::/24fca4:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fca4:4900::/24fca4:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fca4:4a00::/24fca4:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fca4:4b00::/24fca4:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fca4:4c00::/24fca4:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fca4:4d00::/24fca4:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fca4:4e00::/24fca4:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fca4:4f00::/24fca4:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fca4:5000::/24fca4:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fca4:5100::/24fca4:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fca4:5200::/24fca4:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fca4:5300::/24fca4:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fca4:5400::/24fca4:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fca4:5500::/24fca4:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fca4:5600::/24fca4:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fca4:5700::/24fca4:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fca4:5800::/24fca4:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fca4:5900::/24fca4:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fca4:5a00::/24fca4:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fca4:5b00::/24fca4:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fca4:5c00::/24fca4:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fca4:5d00::/24fca4:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fca4:5e00::/24fca4:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fca4:5f00::/24fca4:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fca4:6000::/24fca4:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fca4:6100::/24fca4:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fca4:6200::/24fca4:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fca4:6300::/24fca4:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fca4:6400::/24fca4:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fca4:6500::/24fca4:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fca4:6600::/24fca4:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fca4:6700::/24fca4:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fca4:6800::/24fca4:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fca4:6900::/24fca4:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fca4:6a00::/24fca4:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fca4:6b00::/24fca4:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fca4:6c00::/24fca4:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fca4:6d00::/24fca4:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fca4:6e00::/24fca4:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fca4:6f00::/24fca4:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fca4:7000::/24fca4:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fca4:7100::/24fca4:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fca4:7200::/24fca4:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fca4:7300::/24fca4:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fca4:7400::/24fca4:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fca4:7500::/24fca4:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fca4:7600::/24fca4:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fca4:7700::/24fca4:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fca4:7800::/24fca4:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fca4:7900::/24fca4:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fca4:7a00::/24fca4:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fca4:7b00::/24fca4:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fca4:7c00::/24fca4:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fca4:7d00::/24fca4:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fca4:7e00::/24fca4:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fca4:7f00::/24fca4:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fca4:8000::/24fca4:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fca4:8100::/24fca4:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fca4:8200::/24fca4:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fca4:8300::/24fca4:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fca4:8400::/24fca4:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fca4:8500::/24fca4:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fca4:8600::/24fca4:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fca4:8700::/24fca4:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fca4:8800::/24fca4:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fca4:8900::/24fca4:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fca4:8a00::/24fca4:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fca4:8b00::/24fca4:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fca4:8c00::/24fca4:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fca4:8d00::/24fca4:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fca4:8e00::/24fca4:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fca4:8f00::/24fca4:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fca4:9000::/24fca4:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fca4:9100::/24fca4:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fca4:9200::/24fca4:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fca4:9300::/24fca4:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fca4:9400::/24fca4:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fca4:9500::/24fca4:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fca4:9600::/24fca4:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fca4:9700::/24fca4:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fca4:9800::/24fca4:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fca4:9900::/24fca4:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fca4:9a00::/24fca4:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fca4:9b00::/24fca4:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fca4:9c00::/24fca4:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fca4:9d00::/24fca4:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fca4:9e00::/24fca4:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fca4:9f00::/24fca4:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fca4:a000::/24fca4:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fca4:a100::/24fca4:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fca4:a200::/24fca4:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fca4:a300::/24fca4:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fca4:a400::/24fca4:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fca4:a500::/24fca4:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fca4:a600::/24fca4:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fca4:a700::/24fca4:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fca4:a800::/24fca4:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fca4:a900::/24fca4:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fca4:aa00::/24fca4:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fca4:ab00::/24fca4:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fca4:ac00::/24fca4:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fca4:ad00::/24fca4:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fca4:ae00::/24fca4:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fca4:af00::/24fca4:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fca4:b000::/24fca4:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fca4:b100::/24fca4:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fca4:b200::/24fca4:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fca4:b300::/24fca4:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fca4:b400::/24fca4:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fca4:b500::/24fca4:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fca4:b600::/24fca4:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fca4:b700::/24fca4:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fca4:b800::/24fca4:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fca4:b900::/24fca4:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fca4:ba00::/24fca4:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fca4:bb00::/24fca4:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fca4:bc00::/24fca4:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fca4:bd00::/24fca4:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fca4:be00::/24fca4:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fca4:bf00::/24fca4:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fca4:c000::/24fca4:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fca4:c100::/24fca4:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fca4:c200::/24fca4:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fca4:c300::/24fca4:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fca4:c400::/24fca4:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fca4:c500::/24fca4:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fca4:c600::/24fca4:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fca4:c700::/24fca4:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fca4:c800::/24fca4:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fca4:c900::/24fca4:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fca4:ca00::/24fca4:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fca4:cb00::/24fca4:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fca4:cc00::/24fca4:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fca4:cd00::/24fca4:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fca4:ce00::/24fca4:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fca4:cf00::/24fca4:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fca4:d000::/24fca4:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fca4:d100::/24fca4:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fca4:d200::/24fca4:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fca4:d300::/24fca4:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fca4:d400::/24fca4:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fca4:d500::/24fca4:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fca4:d600::/24fca4:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fca4:d700::/24fca4:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fca4:d800::/24fca4:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fca4:d900::/24fca4:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fca4:da00::/24fca4:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fca4:db00::/24fca4:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fca4:dc00::/24fca4:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fca4:dd00::/24fca4:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fca4:de00::/24fca4:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fca4:df00::/24fca4:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fca4:e000::/24fca4:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fca4:e100::/24fca4:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fca4:e200::/24fca4:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fca4:e300::/24fca4:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fca4:e400::/24fca4:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fca4:e500::/24fca4:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fca4:e600::/24fca4:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fca4:e700::/24fca4:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fca4:e800::/24fca4:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fca4:e900::/24fca4:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fca4:ea00::/24fca4:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fca4:eb00::/24fca4:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fca4:ec00::/24fca4:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fca4:ed00::/24fca4:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fca4:ee00::/24fca4:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fca4:ef00::/24fca4:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fca4:f000::/24fca4:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fca4:f100::/24fca4:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fca4:f200::/24fca4:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fca4:f300::/24fca4:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fca4:f400::/24fca4:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fca4:f500::/24fca4:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fca4:f600::/24fca4:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fca4:f700::/24fca4:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fca4:f800::/24fca4:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fca4:f900::/24fca4:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fca4:fa00::/24fca4:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fca4:fb00::/24fca4:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fca4:fc00::/24fca4:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fca4:fd00::/24fca4:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fca4:fe00::/24fca4:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fca4:ff00::/24fca4: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.