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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
fcd6::/16
First address
fcd6::
Last address
fcd6: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
fcd6:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
6.d.c.f.ip6.arpa
Split into smaller subnets/32
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fcd6::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1fcd6::/32fcd6:0:ffff:ffff:ffff:ffff:ffff:ffff
2fcd6:1::/32fcd6:1:ffff:ffff:ffff:ffff:ffff:ffff
3fcd6:2::/32fcd6:2:ffff:ffff:ffff:ffff:ffff:ffff
4fcd6:3::/32fcd6:3:ffff:ffff:ffff:ffff:ffff:ffff
5fcd6:4::/32fcd6:4:ffff:ffff:ffff:ffff:ffff:ffff
6fcd6:5::/32fcd6:5:ffff:ffff:ffff:ffff:ffff:ffff
7fcd6:6::/32fcd6:6:ffff:ffff:ffff:ffff:ffff:ffff
8fcd6:7::/32fcd6:7:ffff:ffff:ffff:ffff:ffff:ffff
9fcd6:8::/32fcd6:8:ffff:ffff:ffff:ffff:ffff:ffff
10fcd6:9::/32fcd6:9:ffff:ffff:ffff:ffff:ffff:ffff
11fcd6:a::/32fcd6:a:ffff:ffff:ffff:ffff:ffff:ffff
12fcd6:b::/32fcd6:b:ffff:ffff:ffff:ffff:ffff:ffff
13fcd6:c::/32fcd6:c:ffff:ffff:ffff:ffff:ffff:ffff
14fcd6:d::/32fcd6:d:ffff:ffff:ffff:ffff:ffff:ffff
15fcd6:e::/32fcd6:e:ffff:ffff:ffff:ffff:ffff:ffff
16fcd6:f::/32fcd6:f:ffff:ffff:ffff:ffff:ffff:ffff
17fcd6:10::/32fcd6:10:ffff:ffff:ffff:ffff:ffff:ffff
18fcd6:11::/32fcd6:11:ffff:ffff:ffff:ffff:ffff:ffff
19fcd6:12::/32fcd6:12:ffff:ffff:ffff:ffff:ffff:ffff
20fcd6:13::/32fcd6:13:ffff:ffff:ffff:ffff:ffff:ffff
21fcd6:14::/32fcd6:14:ffff:ffff:ffff:ffff:ffff:ffff
22fcd6:15::/32fcd6:15:ffff:ffff:ffff:ffff:ffff:ffff
23fcd6:16::/32fcd6:16:ffff:ffff:ffff:ffff:ffff:ffff
24fcd6:17::/32fcd6:17:ffff:ffff:ffff:ffff:ffff:ffff
25fcd6:18::/32fcd6:18:ffff:ffff:ffff:ffff:ffff:ffff
26fcd6:19::/32fcd6:19:ffff:ffff:ffff:ffff:ffff:ffff
27fcd6:1a::/32fcd6:1a:ffff:ffff:ffff:ffff:ffff:ffff
28fcd6:1b::/32fcd6:1b:ffff:ffff:ffff:ffff:ffff:ffff
29fcd6:1c::/32fcd6:1c:ffff:ffff:ffff:ffff:ffff:ffff
30fcd6:1d::/32fcd6:1d:ffff:ffff:ffff:ffff:ffff:ffff
31fcd6:1e::/32fcd6:1e:ffff:ffff:ffff:ffff:ffff:ffff
32fcd6:1f::/32fcd6:1f:ffff:ffff:ffff:ffff:ffff:ffff
33fcd6:20::/32fcd6:20:ffff:ffff:ffff:ffff:ffff:ffff
34fcd6:21::/32fcd6:21:ffff:ffff:ffff:ffff:ffff:ffff
35fcd6:22::/32fcd6:22:ffff:ffff:ffff:ffff:ffff:ffff
36fcd6:23::/32fcd6:23:ffff:ffff:ffff:ffff:ffff:ffff
37fcd6:24::/32fcd6:24:ffff:ffff:ffff:ffff:ffff:ffff
38fcd6:25::/32fcd6:25:ffff:ffff:ffff:ffff:ffff:ffff
39fcd6:26::/32fcd6:26:ffff:ffff:ffff:ffff:ffff:ffff
40fcd6:27::/32fcd6:27:ffff:ffff:ffff:ffff:ffff:ffff
41fcd6:28::/32fcd6:28:ffff:ffff:ffff:ffff:ffff:ffff
42fcd6:29::/32fcd6:29:ffff:ffff:ffff:ffff:ffff:ffff
43fcd6:2a::/32fcd6:2a:ffff:ffff:ffff:ffff:ffff:ffff
44fcd6:2b::/32fcd6:2b:ffff:ffff:ffff:ffff:ffff:ffff
45fcd6:2c::/32fcd6:2c:ffff:ffff:ffff:ffff:ffff:ffff
46fcd6:2d::/32fcd6:2d:ffff:ffff:ffff:ffff:ffff:ffff
47fcd6:2e::/32fcd6:2e:ffff:ffff:ffff:ffff:ffff:ffff
48fcd6:2f::/32fcd6:2f:ffff:ffff:ffff:ffff:ffff:ffff
49fcd6:30::/32fcd6:30:ffff:ffff:ffff:ffff:ffff:ffff
50fcd6:31::/32fcd6:31:ffff:ffff:ffff:ffff:ffff:ffff
51fcd6:32::/32fcd6:32:ffff:ffff:ffff:ffff:ffff:ffff
52fcd6:33::/32fcd6:33:ffff:ffff:ffff:ffff:ffff:ffff
53fcd6:34::/32fcd6:34:ffff:ffff:ffff:ffff:ffff:ffff
54fcd6:35::/32fcd6:35:ffff:ffff:ffff:ffff:ffff:ffff
55fcd6:36::/32fcd6:36:ffff:ffff:ffff:ffff:ffff:ffff
56fcd6:37::/32fcd6:37:ffff:ffff:ffff:ffff:ffff:ffff
57fcd6:38::/32fcd6:38:ffff:ffff:ffff:ffff:ffff:ffff
58fcd6:39::/32fcd6:39:ffff:ffff:ffff:ffff:ffff:ffff
59fcd6:3a::/32fcd6:3a:ffff:ffff:ffff:ffff:ffff:ffff
60fcd6:3b::/32fcd6:3b:ffff:ffff:ffff:ffff:ffff:ffff
61fcd6:3c::/32fcd6:3c:ffff:ffff:ffff:ffff:ffff:ffff
62fcd6:3d::/32fcd6:3d:ffff:ffff:ffff:ffff:ffff:ffff
63fcd6:3e::/32fcd6:3e:ffff:ffff:ffff:ffff:ffff:ffff
64fcd6:3f::/32fcd6:3f:ffff:ffff:ffff:ffff:ffff:ffff
65fcd6:40::/32fcd6:40:ffff:ffff:ffff:ffff:ffff:ffff
66fcd6:41::/32fcd6:41:ffff:ffff:ffff:ffff:ffff:ffff
67fcd6:42::/32fcd6:42:ffff:ffff:ffff:ffff:ffff:ffff
68fcd6:43::/32fcd6:43:ffff:ffff:ffff:ffff:ffff:ffff
69fcd6:44::/32fcd6:44:ffff:ffff:ffff:ffff:ffff:ffff
70fcd6:45::/32fcd6:45:ffff:ffff:ffff:ffff:ffff:ffff
71fcd6:46::/32fcd6:46:ffff:ffff:ffff:ffff:ffff:ffff
72fcd6:47::/32fcd6:47:ffff:ffff:ffff:ffff:ffff:ffff
73fcd6:48::/32fcd6:48:ffff:ffff:ffff:ffff:ffff:ffff
74fcd6:49::/32fcd6:49:ffff:ffff:ffff:ffff:ffff:ffff
75fcd6:4a::/32fcd6:4a:ffff:ffff:ffff:ffff:ffff:ffff
76fcd6:4b::/32fcd6:4b:ffff:ffff:ffff:ffff:ffff:ffff
77fcd6:4c::/32fcd6:4c:ffff:ffff:ffff:ffff:ffff:ffff
78fcd6:4d::/32fcd6:4d:ffff:ffff:ffff:ffff:ffff:ffff
79fcd6:4e::/32fcd6:4e:ffff:ffff:ffff:ffff:ffff:ffff
80fcd6:4f::/32fcd6:4f:ffff:ffff:ffff:ffff:ffff:ffff
81fcd6:50::/32fcd6:50:ffff:ffff:ffff:ffff:ffff:ffff
82fcd6:51::/32fcd6:51:ffff:ffff:ffff:ffff:ffff:ffff
83fcd6:52::/32fcd6:52:ffff:ffff:ffff:ffff:ffff:ffff
84fcd6:53::/32fcd6:53:ffff:ffff:ffff:ffff:ffff:ffff
85fcd6:54::/32fcd6:54:ffff:ffff:ffff:ffff:ffff:ffff
86fcd6:55::/32fcd6:55:ffff:ffff:ffff:ffff:ffff:ffff
87fcd6:56::/32fcd6:56:ffff:ffff:ffff:ffff:ffff:ffff
88fcd6:57::/32fcd6:57:ffff:ffff:ffff:ffff:ffff:ffff
89fcd6:58::/32fcd6:58:ffff:ffff:ffff:ffff:ffff:ffff
90fcd6:59::/32fcd6:59:ffff:ffff:ffff:ffff:ffff:ffff
91fcd6:5a::/32fcd6:5a:ffff:ffff:ffff:ffff:ffff:ffff
92fcd6:5b::/32fcd6:5b:ffff:ffff:ffff:ffff:ffff:ffff
93fcd6:5c::/32fcd6:5c:ffff:ffff:ffff:ffff:ffff:ffff
94fcd6:5d::/32fcd6:5d:ffff:ffff:ffff:ffff:ffff:ffff
95fcd6:5e::/32fcd6:5e:ffff:ffff:ffff:ffff:ffff:ffff
96fcd6:5f::/32fcd6:5f:ffff:ffff:ffff:ffff:ffff:ffff
97fcd6:60::/32fcd6:60:ffff:ffff:ffff:ffff:ffff:ffff
98fcd6:61::/32fcd6:61:ffff:ffff:ffff:ffff:ffff:ffff
99fcd6:62::/32fcd6:62:ffff:ffff:ffff:ffff:ffff:ffff
100fcd6:63::/32fcd6:63:ffff:ffff:ffff:ffff:ffff:ffff
101fcd6:64::/32fcd6:64:ffff:ffff:ffff:ffff:ffff:ffff
102fcd6:65::/32fcd6:65:ffff:ffff:ffff:ffff:ffff:ffff
103fcd6:66::/32fcd6:66:ffff:ffff:ffff:ffff:ffff:ffff
104fcd6:67::/32fcd6:67:ffff:ffff:ffff:ffff:ffff:ffff
105fcd6:68::/32fcd6:68:ffff:ffff:ffff:ffff:ffff:ffff
106fcd6:69::/32fcd6:69:ffff:ffff:ffff:ffff:ffff:ffff
107fcd6:6a::/32fcd6:6a:ffff:ffff:ffff:ffff:ffff:ffff
108fcd6:6b::/32fcd6:6b:ffff:ffff:ffff:ffff:ffff:ffff
109fcd6:6c::/32fcd6:6c:ffff:ffff:ffff:ffff:ffff:ffff
110fcd6:6d::/32fcd6:6d:ffff:ffff:ffff:ffff:ffff:ffff
111fcd6:6e::/32fcd6:6e:ffff:ffff:ffff:ffff:ffff:ffff
112fcd6:6f::/32fcd6:6f:ffff:ffff:ffff:ffff:ffff:ffff
113fcd6:70::/32fcd6:70:ffff:ffff:ffff:ffff:ffff:ffff
114fcd6:71::/32fcd6:71:ffff:ffff:ffff:ffff:ffff:ffff
115fcd6:72::/32fcd6:72:ffff:ffff:ffff:ffff:ffff:ffff
116fcd6:73::/32fcd6:73:ffff:ffff:ffff:ffff:ffff:ffff
117fcd6:74::/32fcd6:74:ffff:ffff:ffff:ffff:ffff:ffff
118fcd6:75::/32fcd6:75:ffff:ffff:ffff:ffff:ffff:ffff
119fcd6:76::/32fcd6:76:ffff:ffff:ffff:ffff:ffff:ffff
120fcd6:77::/32fcd6:77:ffff:ffff:ffff:ffff:ffff:ffff
121fcd6:78::/32fcd6:78:ffff:ffff:ffff:ffff:ffff:ffff
122fcd6:79::/32fcd6:79:ffff:ffff:ffff:ffff:ffff:ffff
123fcd6:7a::/32fcd6:7a:ffff:ffff:ffff:ffff:ffff:ffff
124fcd6:7b::/32fcd6:7b:ffff:ffff:ffff:ffff:ffff:ffff
125fcd6:7c::/32fcd6:7c:ffff:ffff:ffff:ffff:ffff:ffff
126fcd6:7d::/32fcd6:7d:ffff:ffff:ffff:ffff:ffff:ffff
127fcd6:7e::/32fcd6:7e:ffff:ffff:ffff:ffff:ffff:ffff
128fcd6:7f::/32fcd6:7f:ffff:ffff:ffff:ffff:ffff:ffff
129fcd6:80::/32fcd6:80:ffff:ffff:ffff:ffff:ffff:ffff
130fcd6:81::/32fcd6:81:ffff:ffff:ffff:ffff:ffff:ffff
131fcd6:82::/32fcd6:82:ffff:ffff:ffff:ffff:ffff:ffff
132fcd6:83::/32fcd6:83:ffff:ffff:ffff:ffff:ffff:ffff
133fcd6:84::/32fcd6:84:ffff:ffff:ffff:ffff:ffff:ffff
134fcd6:85::/32fcd6:85:ffff:ffff:ffff:ffff:ffff:ffff
135fcd6:86::/32fcd6:86:ffff:ffff:ffff:ffff:ffff:ffff
136fcd6:87::/32fcd6:87:ffff:ffff:ffff:ffff:ffff:ffff
137fcd6:88::/32fcd6:88:ffff:ffff:ffff:ffff:ffff:ffff
138fcd6:89::/32fcd6:89:ffff:ffff:ffff:ffff:ffff:ffff
139fcd6:8a::/32fcd6:8a:ffff:ffff:ffff:ffff:ffff:ffff
140fcd6:8b::/32fcd6:8b:ffff:ffff:ffff:ffff:ffff:ffff
141fcd6:8c::/32fcd6:8c:ffff:ffff:ffff:ffff:ffff:ffff
142fcd6:8d::/32fcd6:8d:ffff:ffff:ffff:ffff:ffff:ffff
143fcd6:8e::/32fcd6:8e:ffff:ffff:ffff:ffff:ffff:ffff
144fcd6:8f::/32fcd6:8f:ffff:ffff:ffff:ffff:ffff:ffff
145fcd6:90::/32fcd6:90:ffff:ffff:ffff:ffff:ffff:ffff
146fcd6:91::/32fcd6:91:ffff:ffff:ffff:ffff:ffff:ffff
147fcd6:92::/32fcd6:92:ffff:ffff:ffff:ffff:ffff:ffff
148fcd6:93::/32fcd6:93:ffff:ffff:ffff:ffff:ffff:ffff
149fcd6:94::/32fcd6:94:ffff:ffff:ffff:ffff:ffff:ffff
150fcd6:95::/32fcd6:95:ffff:ffff:ffff:ffff:ffff:ffff
151fcd6:96::/32fcd6:96:ffff:ffff:ffff:ffff:ffff:ffff
152fcd6:97::/32fcd6:97:ffff:ffff:ffff:ffff:ffff:ffff
153fcd6:98::/32fcd6:98:ffff:ffff:ffff:ffff:ffff:ffff
154fcd6:99::/32fcd6:99:ffff:ffff:ffff:ffff:ffff:ffff
155fcd6:9a::/32fcd6:9a:ffff:ffff:ffff:ffff:ffff:ffff
156fcd6:9b::/32fcd6:9b:ffff:ffff:ffff:ffff:ffff:ffff
157fcd6:9c::/32fcd6:9c:ffff:ffff:ffff:ffff:ffff:ffff
158fcd6:9d::/32fcd6:9d:ffff:ffff:ffff:ffff:ffff:ffff
159fcd6:9e::/32fcd6:9e:ffff:ffff:ffff:ffff:ffff:ffff
160fcd6:9f::/32fcd6:9f:ffff:ffff:ffff:ffff:ffff:ffff
161fcd6:a0::/32fcd6:a0:ffff:ffff:ffff:ffff:ffff:ffff
162fcd6:a1::/32fcd6:a1:ffff:ffff:ffff:ffff:ffff:ffff
163fcd6:a2::/32fcd6:a2:ffff:ffff:ffff:ffff:ffff:ffff
164fcd6:a3::/32fcd6:a3:ffff:ffff:ffff:ffff:ffff:ffff
165fcd6:a4::/32fcd6:a4:ffff:ffff:ffff:ffff:ffff:ffff
166fcd6:a5::/32fcd6:a5:ffff:ffff:ffff:ffff:ffff:ffff
167fcd6:a6::/32fcd6:a6:ffff:ffff:ffff:ffff:ffff:ffff
168fcd6:a7::/32fcd6:a7:ffff:ffff:ffff:ffff:ffff:ffff
169fcd6:a8::/32fcd6:a8:ffff:ffff:ffff:ffff:ffff:ffff
170fcd6:a9::/32fcd6:a9:ffff:ffff:ffff:ffff:ffff:ffff
171fcd6:aa::/32fcd6:aa:ffff:ffff:ffff:ffff:ffff:ffff
172fcd6:ab::/32fcd6:ab:ffff:ffff:ffff:ffff:ffff:ffff
173fcd6:ac::/32fcd6:ac:ffff:ffff:ffff:ffff:ffff:ffff
174fcd6:ad::/32fcd6:ad:ffff:ffff:ffff:ffff:ffff:ffff
175fcd6:ae::/32fcd6:ae:ffff:ffff:ffff:ffff:ffff:ffff
176fcd6:af::/32fcd6:af:ffff:ffff:ffff:ffff:ffff:ffff
177fcd6:b0::/32fcd6:b0:ffff:ffff:ffff:ffff:ffff:ffff
178fcd6:b1::/32fcd6:b1:ffff:ffff:ffff:ffff:ffff:ffff
179fcd6:b2::/32fcd6:b2:ffff:ffff:ffff:ffff:ffff:ffff
180fcd6:b3::/32fcd6:b3:ffff:ffff:ffff:ffff:ffff:ffff
181fcd6:b4::/32fcd6:b4:ffff:ffff:ffff:ffff:ffff:ffff
182fcd6:b5::/32fcd6:b5:ffff:ffff:ffff:ffff:ffff:ffff
183fcd6:b6::/32fcd6:b6:ffff:ffff:ffff:ffff:ffff:ffff
184fcd6:b7::/32fcd6:b7:ffff:ffff:ffff:ffff:ffff:ffff
185fcd6:b8::/32fcd6:b8:ffff:ffff:ffff:ffff:ffff:ffff
186fcd6:b9::/32fcd6:b9:ffff:ffff:ffff:ffff:ffff:ffff
187fcd6:ba::/32fcd6:ba:ffff:ffff:ffff:ffff:ffff:ffff
188fcd6:bb::/32fcd6:bb:ffff:ffff:ffff:ffff:ffff:ffff
189fcd6:bc::/32fcd6:bc:ffff:ffff:ffff:ffff:ffff:ffff
190fcd6:bd::/32fcd6:bd:ffff:ffff:ffff:ffff:ffff:ffff
191fcd6:be::/32fcd6:be:ffff:ffff:ffff:ffff:ffff:ffff
192fcd6:bf::/32fcd6:bf:ffff:ffff:ffff:ffff:ffff:ffff
193fcd6:c0::/32fcd6:c0:ffff:ffff:ffff:ffff:ffff:ffff
194fcd6:c1::/32fcd6:c1:ffff:ffff:ffff:ffff:ffff:ffff
195fcd6:c2::/32fcd6:c2:ffff:ffff:ffff:ffff:ffff:ffff
196fcd6:c3::/32fcd6:c3:ffff:ffff:ffff:ffff:ffff:ffff
197fcd6:c4::/32fcd6:c4:ffff:ffff:ffff:ffff:ffff:ffff
198fcd6:c5::/32fcd6:c5:ffff:ffff:ffff:ffff:ffff:ffff
199fcd6:c6::/32fcd6:c6:ffff:ffff:ffff:ffff:ffff:ffff
200fcd6:c7::/32fcd6:c7:ffff:ffff:ffff:ffff:ffff:ffff
201fcd6:c8::/32fcd6:c8:ffff:ffff:ffff:ffff:ffff:ffff
202fcd6:c9::/32fcd6:c9:ffff:ffff:ffff:ffff:ffff:ffff
203fcd6:ca::/32fcd6:ca:ffff:ffff:ffff:ffff:ffff:ffff
204fcd6:cb::/32fcd6:cb:ffff:ffff:ffff:ffff:ffff:ffff
205fcd6:cc::/32fcd6:cc:ffff:ffff:ffff:ffff:ffff:ffff
206fcd6:cd::/32fcd6:cd:ffff:ffff:ffff:ffff:ffff:ffff
207fcd6:ce::/32fcd6:ce:ffff:ffff:ffff:ffff:ffff:ffff
208fcd6:cf::/32fcd6:cf:ffff:ffff:ffff:ffff:ffff:ffff
209fcd6:d0::/32fcd6:d0:ffff:ffff:ffff:ffff:ffff:ffff
210fcd6:d1::/32fcd6:d1:ffff:ffff:ffff:ffff:ffff:ffff
211fcd6:d2::/32fcd6:d2:ffff:ffff:ffff:ffff:ffff:ffff
212fcd6:d3::/32fcd6:d3:ffff:ffff:ffff:ffff:ffff:ffff
213fcd6:d4::/32fcd6:d4:ffff:ffff:ffff:ffff:ffff:ffff
214fcd6:d5::/32fcd6:d5:ffff:ffff:ffff:ffff:ffff:ffff
215fcd6:d6::/32fcd6:d6:ffff:ffff:ffff:ffff:ffff:ffff
216fcd6:d7::/32fcd6:d7:ffff:ffff:ffff:ffff:ffff:ffff
217fcd6:d8::/32fcd6:d8:ffff:ffff:ffff:ffff:ffff:ffff
218fcd6:d9::/32fcd6:d9:ffff:ffff:ffff:ffff:ffff:ffff
219fcd6:da::/32fcd6:da:ffff:ffff:ffff:ffff:ffff:ffff
220fcd6:db::/32fcd6:db:ffff:ffff:ffff:ffff:ffff:ffff
221fcd6:dc::/32fcd6:dc:ffff:ffff:ffff:ffff:ffff:ffff
222fcd6:dd::/32fcd6:dd:ffff:ffff:ffff:ffff:ffff:ffff
223fcd6:de::/32fcd6:de:ffff:ffff:ffff:ffff:ffff:ffff
224fcd6:df::/32fcd6:df:ffff:ffff:ffff:ffff:ffff:ffff
225fcd6:e0::/32fcd6:e0:ffff:ffff:ffff:ffff:ffff:ffff
226fcd6:e1::/32fcd6:e1:ffff:ffff:ffff:ffff:ffff:ffff
227fcd6:e2::/32fcd6:e2:ffff:ffff:ffff:ffff:ffff:ffff
228fcd6:e3::/32fcd6:e3:ffff:ffff:ffff:ffff:ffff:ffff
229fcd6:e4::/32fcd6:e4:ffff:ffff:ffff:ffff:ffff:ffff
230fcd6:e5::/32fcd6:e5:ffff:ffff:ffff:ffff:ffff:ffff
231fcd6:e6::/32fcd6:e6:ffff:ffff:ffff:ffff:ffff:ffff
232fcd6:e7::/32fcd6:e7:ffff:ffff:ffff:ffff:ffff:ffff
233fcd6:e8::/32fcd6:e8:ffff:ffff:ffff:ffff:ffff:ffff
234fcd6:e9::/32fcd6:e9:ffff:ffff:ffff:ffff:ffff:ffff
235fcd6:ea::/32fcd6:ea:ffff:ffff:ffff:ffff:ffff:ffff
236fcd6:eb::/32fcd6:eb:ffff:ffff:ffff:ffff:ffff:ffff
237fcd6:ec::/32fcd6:ec:ffff:ffff:ffff:ffff:ffff:ffff
238fcd6:ed::/32fcd6:ed:ffff:ffff:ffff:ffff:ffff:ffff
239fcd6:ee::/32fcd6:ee:ffff:ffff:ffff:ffff:ffff:ffff
240fcd6:ef::/32fcd6:ef:ffff:ffff:ffff:ffff:ffff:ffff
241fcd6:f0::/32fcd6:f0:ffff:ffff:ffff:ffff:ffff:ffff
242fcd6:f1::/32fcd6:f1:ffff:ffff:ffff:ffff:ffff:ffff
243fcd6:f2::/32fcd6:f2:ffff:ffff:ffff:ffff:ffff:ffff
244fcd6:f3::/32fcd6:f3:ffff:ffff:ffff:ffff:ffff:ffff
245fcd6:f4::/32fcd6:f4:ffff:ffff:ffff:ffff:ffff:ffff
246fcd6:f5::/32fcd6:f5:ffff:ffff:ffff:ffff:ffff:ffff
247fcd6:f6::/32fcd6:f6:ffff:ffff:ffff:ffff:ffff:ffff
248fcd6:f7::/32fcd6:f7:ffff:ffff:ffff:ffff:ffff:ffff
249fcd6:f8::/32fcd6:f8:ffff:ffff:ffff:ffff:ffff:ffff
250fcd6:f9::/32fcd6:f9:ffff:ffff:ffff:ffff:ffff:ffff
251fcd6:fa::/32fcd6:fa:ffff:ffff:ffff:ffff:ffff:ffff
252fcd6:fb::/32fcd6:fb:ffff:ffff:ffff:ffff:ffff:ffff
253fcd6:fc::/32fcd6:fc:ffff:ffff:ffff:ffff:ffff:ffff
254fcd6:fd::/32fcd6:fd:ffff:ffff:ffff:ffff:ffff:ffff
255fcd6:fe::/32fcd6:fe:ffff:ffff:ffff:ffff:ffff:ffff
256fcd6:ff::/32fcd6:ff: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.