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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
fca3::/16
First address
fca3::
Last address
fca3: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
fca3:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
3.a.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)

fca3::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1fca3::/32fca3:0:ffff:ffff:ffff:ffff:ffff:ffff
2fca3:1::/32fca3:1:ffff:ffff:ffff:ffff:ffff:ffff
3fca3:2::/32fca3:2:ffff:ffff:ffff:ffff:ffff:ffff
4fca3:3::/32fca3:3:ffff:ffff:ffff:ffff:ffff:ffff
5fca3:4::/32fca3:4:ffff:ffff:ffff:ffff:ffff:ffff
6fca3:5::/32fca3:5:ffff:ffff:ffff:ffff:ffff:ffff
7fca3:6::/32fca3:6:ffff:ffff:ffff:ffff:ffff:ffff
8fca3:7::/32fca3:7:ffff:ffff:ffff:ffff:ffff:ffff
9fca3:8::/32fca3:8:ffff:ffff:ffff:ffff:ffff:ffff
10fca3:9::/32fca3:9:ffff:ffff:ffff:ffff:ffff:ffff
11fca3:a::/32fca3:a:ffff:ffff:ffff:ffff:ffff:ffff
12fca3:b::/32fca3:b:ffff:ffff:ffff:ffff:ffff:ffff
13fca3:c::/32fca3:c:ffff:ffff:ffff:ffff:ffff:ffff
14fca3:d::/32fca3:d:ffff:ffff:ffff:ffff:ffff:ffff
15fca3:e::/32fca3:e:ffff:ffff:ffff:ffff:ffff:ffff
16fca3:f::/32fca3:f:ffff:ffff:ffff:ffff:ffff:ffff
17fca3:10::/32fca3:10:ffff:ffff:ffff:ffff:ffff:ffff
18fca3:11::/32fca3:11:ffff:ffff:ffff:ffff:ffff:ffff
19fca3:12::/32fca3:12:ffff:ffff:ffff:ffff:ffff:ffff
20fca3:13::/32fca3:13:ffff:ffff:ffff:ffff:ffff:ffff
21fca3:14::/32fca3:14:ffff:ffff:ffff:ffff:ffff:ffff
22fca3:15::/32fca3:15:ffff:ffff:ffff:ffff:ffff:ffff
23fca3:16::/32fca3:16:ffff:ffff:ffff:ffff:ffff:ffff
24fca3:17::/32fca3:17:ffff:ffff:ffff:ffff:ffff:ffff
25fca3:18::/32fca3:18:ffff:ffff:ffff:ffff:ffff:ffff
26fca3:19::/32fca3:19:ffff:ffff:ffff:ffff:ffff:ffff
27fca3:1a::/32fca3:1a:ffff:ffff:ffff:ffff:ffff:ffff
28fca3:1b::/32fca3:1b:ffff:ffff:ffff:ffff:ffff:ffff
29fca3:1c::/32fca3:1c:ffff:ffff:ffff:ffff:ffff:ffff
30fca3:1d::/32fca3:1d:ffff:ffff:ffff:ffff:ffff:ffff
31fca3:1e::/32fca3:1e:ffff:ffff:ffff:ffff:ffff:ffff
32fca3:1f::/32fca3:1f:ffff:ffff:ffff:ffff:ffff:ffff
33fca3:20::/32fca3:20:ffff:ffff:ffff:ffff:ffff:ffff
34fca3:21::/32fca3:21:ffff:ffff:ffff:ffff:ffff:ffff
35fca3:22::/32fca3:22:ffff:ffff:ffff:ffff:ffff:ffff
36fca3:23::/32fca3:23:ffff:ffff:ffff:ffff:ffff:ffff
37fca3:24::/32fca3:24:ffff:ffff:ffff:ffff:ffff:ffff
38fca3:25::/32fca3:25:ffff:ffff:ffff:ffff:ffff:ffff
39fca3:26::/32fca3:26:ffff:ffff:ffff:ffff:ffff:ffff
40fca3:27::/32fca3:27:ffff:ffff:ffff:ffff:ffff:ffff
41fca3:28::/32fca3:28:ffff:ffff:ffff:ffff:ffff:ffff
42fca3:29::/32fca3:29:ffff:ffff:ffff:ffff:ffff:ffff
43fca3:2a::/32fca3:2a:ffff:ffff:ffff:ffff:ffff:ffff
44fca3:2b::/32fca3:2b:ffff:ffff:ffff:ffff:ffff:ffff
45fca3:2c::/32fca3:2c:ffff:ffff:ffff:ffff:ffff:ffff
46fca3:2d::/32fca3:2d:ffff:ffff:ffff:ffff:ffff:ffff
47fca3:2e::/32fca3:2e:ffff:ffff:ffff:ffff:ffff:ffff
48fca3:2f::/32fca3:2f:ffff:ffff:ffff:ffff:ffff:ffff
49fca3:30::/32fca3:30:ffff:ffff:ffff:ffff:ffff:ffff
50fca3:31::/32fca3:31:ffff:ffff:ffff:ffff:ffff:ffff
51fca3:32::/32fca3:32:ffff:ffff:ffff:ffff:ffff:ffff
52fca3:33::/32fca3:33:ffff:ffff:ffff:ffff:ffff:ffff
53fca3:34::/32fca3:34:ffff:ffff:ffff:ffff:ffff:ffff
54fca3:35::/32fca3:35:ffff:ffff:ffff:ffff:ffff:ffff
55fca3:36::/32fca3:36:ffff:ffff:ffff:ffff:ffff:ffff
56fca3:37::/32fca3:37:ffff:ffff:ffff:ffff:ffff:ffff
57fca3:38::/32fca3:38:ffff:ffff:ffff:ffff:ffff:ffff
58fca3:39::/32fca3:39:ffff:ffff:ffff:ffff:ffff:ffff
59fca3:3a::/32fca3:3a:ffff:ffff:ffff:ffff:ffff:ffff
60fca3:3b::/32fca3:3b:ffff:ffff:ffff:ffff:ffff:ffff
61fca3:3c::/32fca3:3c:ffff:ffff:ffff:ffff:ffff:ffff
62fca3:3d::/32fca3:3d:ffff:ffff:ffff:ffff:ffff:ffff
63fca3:3e::/32fca3:3e:ffff:ffff:ffff:ffff:ffff:ffff
64fca3:3f::/32fca3:3f:ffff:ffff:ffff:ffff:ffff:ffff
65fca3:40::/32fca3:40:ffff:ffff:ffff:ffff:ffff:ffff
66fca3:41::/32fca3:41:ffff:ffff:ffff:ffff:ffff:ffff
67fca3:42::/32fca3:42:ffff:ffff:ffff:ffff:ffff:ffff
68fca3:43::/32fca3:43:ffff:ffff:ffff:ffff:ffff:ffff
69fca3:44::/32fca3:44:ffff:ffff:ffff:ffff:ffff:ffff
70fca3:45::/32fca3:45:ffff:ffff:ffff:ffff:ffff:ffff
71fca3:46::/32fca3:46:ffff:ffff:ffff:ffff:ffff:ffff
72fca3:47::/32fca3:47:ffff:ffff:ffff:ffff:ffff:ffff
73fca3:48::/32fca3:48:ffff:ffff:ffff:ffff:ffff:ffff
74fca3:49::/32fca3:49:ffff:ffff:ffff:ffff:ffff:ffff
75fca3:4a::/32fca3:4a:ffff:ffff:ffff:ffff:ffff:ffff
76fca3:4b::/32fca3:4b:ffff:ffff:ffff:ffff:ffff:ffff
77fca3:4c::/32fca3:4c:ffff:ffff:ffff:ffff:ffff:ffff
78fca3:4d::/32fca3:4d:ffff:ffff:ffff:ffff:ffff:ffff
79fca3:4e::/32fca3:4e:ffff:ffff:ffff:ffff:ffff:ffff
80fca3:4f::/32fca3:4f:ffff:ffff:ffff:ffff:ffff:ffff
81fca3:50::/32fca3:50:ffff:ffff:ffff:ffff:ffff:ffff
82fca3:51::/32fca3:51:ffff:ffff:ffff:ffff:ffff:ffff
83fca3:52::/32fca3:52:ffff:ffff:ffff:ffff:ffff:ffff
84fca3:53::/32fca3:53:ffff:ffff:ffff:ffff:ffff:ffff
85fca3:54::/32fca3:54:ffff:ffff:ffff:ffff:ffff:ffff
86fca3:55::/32fca3:55:ffff:ffff:ffff:ffff:ffff:ffff
87fca3:56::/32fca3:56:ffff:ffff:ffff:ffff:ffff:ffff
88fca3:57::/32fca3:57:ffff:ffff:ffff:ffff:ffff:ffff
89fca3:58::/32fca3:58:ffff:ffff:ffff:ffff:ffff:ffff
90fca3:59::/32fca3:59:ffff:ffff:ffff:ffff:ffff:ffff
91fca3:5a::/32fca3:5a:ffff:ffff:ffff:ffff:ffff:ffff
92fca3:5b::/32fca3:5b:ffff:ffff:ffff:ffff:ffff:ffff
93fca3:5c::/32fca3:5c:ffff:ffff:ffff:ffff:ffff:ffff
94fca3:5d::/32fca3:5d:ffff:ffff:ffff:ffff:ffff:ffff
95fca3:5e::/32fca3:5e:ffff:ffff:ffff:ffff:ffff:ffff
96fca3:5f::/32fca3:5f:ffff:ffff:ffff:ffff:ffff:ffff
97fca3:60::/32fca3:60:ffff:ffff:ffff:ffff:ffff:ffff
98fca3:61::/32fca3:61:ffff:ffff:ffff:ffff:ffff:ffff
99fca3:62::/32fca3:62:ffff:ffff:ffff:ffff:ffff:ffff
100fca3:63::/32fca3:63:ffff:ffff:ffff:ffff:ffff:ffff
101fca3:64::/32fca3:64:ffff:ffff:ffff:ffff:ffff:ffff
102fca3:65::/32fca3:65:ffff:ffff:ffff:ffff:ffff:ffff
103fca3:66::/32fca3:66:ffff:ffff:ffff:ffff:ffff:ffff
104fca3:67::/32fca3:67:ffff:ffff:ffff:ffff:ffff:ffff
105fca3:68::/32fca3:68:ffff:ffff:ffff:ffff:ffff:ffff
106fca3:69::/32fca3:69:ffff:ffff:ffff:ffff:ffff:ffff
107fca3:6a::/32fca3:6a:ffff:ffff:ffff:ffff:ffff:ffff
108fca3:6b::/32fca3:6b:ffff:ffff:ffff:ffff:ffff:ffff
109fca3:6c::/32fca3:6c:ffff:ffff:ffff:ffff:ffff:ffff
110fca3:6d::/32fca3:6d:ffff:ffff:ffff:ffff:ffff:ffff
111fca3:6e::/32fca3:6e:ffff:ffff:ffff:ffff:ffff:ffff
112fca3:6f::/32fca3:6f:ffff:ffff:ffff:ffff:ffff:ffff
113fca3:70::/32fca3:70:ffff:ffff:ffff:ffff:ffff:ffff
114fca3:71::/32fca3:71:ffff:ffff:ffff:ffff:ffff:ffff
115fca3:72::/32fca3:72:ffff:ffff:ffff:ffff:ffff:ffff
116fca3:73::/32fca3:73:ffff:ffff:ffff:ffff:ffff:ffff
117fca3:74::/32fca3:74:ffff:ffff:ffff:ffff:ffff:ffff
118fca3:75::/32fca3:75:ffff:ffff:ffff:ffff:ffff:ffff
119fca3:76::/32fca3:76:ffff:ffff:ffff:ffff:ffff:ffff
120fca3:77::/32fca3:77:ffff:ffff:ffff:ffff:ffff:ffff
121fca3:78::/32fca3:78:ffff:ffff:ffff:ffff:ffff:ffff
122fca3:79::/32fca3:79:ffff:ffff:ffff:ffff:ffff:ffff
123fca3:7a::/32fca3:7a:ffff:ffff:ffff:ffff:ffff:ffff
124fca3:7b::/32fca3:7b:ffff:ffff:ffff:ffff:ffff:ffff
125fca3:7c::/32fca3:7c:ffff:ffff:ffff:ffff:ffff:ffff
126fca3:7d::/32fca3:7d:ffff:ffff:ffff:ffff:ffff:ffff
127fca3:7e::/32fca3:7e:ffff:ffff:ffff:ffff:ffff:ffff
128fca3:7f::/32fca3:7f:ffff:ffff:ffff:ffff:ffff:ffff
129fca3:80::/32fca3:80:ffff:ffff:ffff:ffff:ffff:ffff
130fca3:81::/32fca3:81:ffff:ffff:ffff:ffff:ffff:ffff
131fca3:82::/32fca3:82:ffff:ffff:ffff:ffff:ffff:ffff
132fca3:83::/32fca3:83:ffff:ffff:ffff:ffff:ffff:ffff
133fca3:84::/32fca3:84:ffff:ffff:ffff:ffff:ffff:ffff
134fca3:85::/32fca3:85:ffff:ffff:ffff:ffff:ffff:ffff
135fca3:86::/32fca3:86:ffff:ffff:ffff:ffff:ffff:ffff
136fca3:87::/32fca3:87:ffff:ffff:ffff:ffff:ffff:ffff
137fca3:88::/32fca3:88:ffff:ffff:ffff:ffff:ffff:ffff
138fca3:89::/32fca3:89:ffff:ffff:ffff:ffff:ffff:ffff
139fca3:8a::/32fca3:8a:ffff:ffff:ffff:ffff:ffff:ffff
140fca3:8b::/32fca3:8b:ffff:ffff:ffff:ffff:ffff:ffff
141fca3:8c::/32fca3:8c:ffff:ffff:ffff:ffff:ffff:ffff
142fca3:8d::/32fca3:8d:ffff:ffff:ffff:ffff:ffff:ffff
143fca3:8e::/32fca3:8e:ffff:ffff:ffff:ffff:ffff:ffff
144fca3:8f::/32fca3:8f:ffff:ffff:ffff:ffff:ffff:ffff
145fca3:90::/32fca3:90:ffff:ffff:ffff:ffff:ffff:ffff
146fca3:91::/32fca3:91:ffff:ffff:ffff:ffff:ffff:ffff
147fca3:92::/32fca3:92:ffff:ffff:ffff:ffff:ffff:ffff
148fca3:93::/32fca3:93:ffff:ffff:ffff:ffff:ffff:ffff
149fca3:94::/32fca3:94:ffff:ffff:ffff:ffff:ffff:ffff
150fca3:95::/32fca3:95:ffff:ffff:ffff:ffff:ffff:ffff
151fca3:96::/32fca3:96:ffff:ffff:ffff:ffff:ffff:ffff
152fca3:97::/32fca3:97:ffff:ffff:ffff:ffff:ffff:ffff
153fca3:98::/32fca3:98:ffff:ffff:ffff:ffff:ffff:ffff
154fca3:99::/32fca3:99:ffff:ffff:ffff:ffff:ffff:ffff
155fca3:9a::/32fca3:9a:ffff:ffff:ffff:ffff:ffff:ffff
156fca3:9b::/32fca3:9b:ffff:ffff:ffff:ffff:ffff:ffff
157fca3:9c::/32fca3:9c:ffff:ffff:ffff:ffff:ffff:ffff
158fca3:9d::/32fca3:9d:ffff:ffff:ffff:ffff:ffff:ffff
159fca3:9e::/32fca3:9e:ffff:ffff:ffff:ffff:ffff:ffff
160fca3:9f::/32fca3:9f:ffff:ffff:ffff:ffff:ffff:ffff
161fca3:a0::/32fca3:a0:ffff:ffff:ffff:ffff:ffff:ffff
162fca3:a1::/32fca3:a1:ffff:ffff:ffff:ffff:ffff:ffff
163fca3:a2::/32fca3:a2:ffff:ffff:ffff:ffff:ffff:ffff
164fca3:a3::/32fca3:a3:ffff:ffff:ffff:ffff:ffff:ffff
165fca3:a4::/32fca3:a4:ffff:ffff:ffff:ffff:ffff:ffff
166fca3:a5::/32fca3:a5:ffff:ffff:ffff:ffff:ffff:ffff
167fca3:a6::/32fca3:a6:ffff:ffff:ffff:ffff:ffff:ffff
168fca3:a7::/32fca3:a7:ffff:ffff:ffff:ffff:ffff:ffff
169fca3:a8::/32fca3:a8:ffff:ffff:ffff:ffff:ffff:ffff
170fca3:a9::/32fca3:a9:ffff:ffff:ffff:ffff:ffff:ffff
171fca3:aa::/32fca3:aa:ffff:ffff:ffff:ffff:ffff:ffff
172fca3:ab::/32fca3:ab:ffff:ffff:ffff:ffff:ffff:ffff
173fca3:ac::/32fca3:ac:ffff:ffff:ffff:ffff:ffff:ffff
174fca3:ad::/32fca3:ad:ffff:ffff:ffff:ffff:ffff:ffff
175fca3:ae::/32fca3:ae:ffff:ffff:ffff:ffff:ffff:ffff
176fca3:af::/32fca3:af:ffff:ffff:ffff:ffff:ffff:ffff
177fca3:b0::/32fca3:b0:ffff:ffff:ffff:ffff:ffff:ffff
178fca3:b1::/32fca3:b1:ffff:ffff:ffff:ffff:ffff:ffff
179fca3:b2::/32fca3:b2:ffff:ffff:ffff:ffff:ffff:ffff
180fca3:b3::/32fca3:b3:ffff:ffff:ffff:ffff:ffff:ffff
181fca3:b4::/32fca3:b4:ffff:ffff:ffff:ffff:ffff:ffff
182fca3:b5::/32fca3:b5:ffff:ffff:ffff:ffff:ffff:ffff
183fca3:b6::/32fca3:b6:ffff:ffff:ffff:ffff:ffff:ffff
184fca3:b7::/32fca3:b7:ffff:ffff:ffff:ffff:ffff:ffff
185fca3:b8::/32fca3:b8:ffff:ffff:ffff:ffff:ffff:ffff
186fca3:b9::/32fca3:b9:ffff:ffff:ffff:ffff:ffff:ffff
187fca3:ba::/32fca3:ba:ffff:ffff:ffff:ffff:ffff:ffff
188fca3:bb::/32fca3:bb:ffff:ffff:ffff:ffff:ffff:ffff
189fca3:bc::/32fca3:bc:ffff:ffff:ffff:ffff:ffff:ffff
190fca3:bd::/32fca3:bd:ffff:ffff:ffff:ffff:ffff:ffff
191fca3:be::/32fca3:be:ffff:ffff:ffff:ffff:ffff:ffff
192fca3:bf::/32fca3:bf:ffff:ffff:ffff:ffff:ffff:ffff
193fca3:c0::/32fca3:c0:ffff:ffff:ffff:ffff:ffff:ffff
194fca3:c1::/32fca3:c1:ffff:ffff:ffff:ffff:ffff:ffff
195fca3:c2::/32fca3:c2:ffff:ffff:ffff:ffff:ffff:ffff
196fca3:c3::/32fca3:c3:ffff:ffff:ffff:ffff:ffff:ffff
197fca3:c4::/32fca3:c4:ffff:ffff:ffff:ffff:ffff:ffff
198fca3:c5::/32fca3:c5:ffff:ffff:ffff:ffff:ffff:ffff
199fca3:c6::/32fca3:c6:ffff:ffff:ffff:ffff:ffff:ffff
200fca3:c7::/32fca3:c7:ffff:ffff:ffff:ffff:ffff:ffff
201fca3:c8::/32fca3:c8:ffff:ffff:ffff:ffff:ffff:ffff
202fca3:c9::/32fca3:c9:ffff:ffff:ffff:ffff:ffff:ffff
203fca3:ca::/32fca3:ca:ffff:ffff:ffff:ffff:ffff:ffff
204fca3:cb::/32fca3:cb:ffff:ffff:ffff:ffff:ffff:ffff
205fca3:cc::/32fca3:cc:ffff:ffff:ffff:ffff:ffff:ffff
206fca3:cd::/32fca3:cd:ffff:ffff:ffff:ffff:ffff:ffff
207fca3:ce::/32fca3:ce:ffff:ffff:ffff:ffff:ffff:ffff
208fca3:cf::/32fca3:cf:ffff:ffff:ffff:ffff:ffff:ffff
209fca3:d0::/32fca3:d0:ffff:ffff:ffff:ffff:ffff:ffff
210fca3:d1::/32fca3:d1:ffff:ffff:ffff:ffff:ffff:ffff
211fca3:d2::/32fca3:d2:ffff:ffff:ffff:ffff:ffff:ffff
212fca3:d3::/32fca3:d3:ffff:ffff:ffff:ffff:ffff:ffff
213fca3:d4::/32fca3:d4:ffff:ffff:ffff:ffff:ffff:ffff
214fca3:d5::/32fca3:d5:ffff:ffff:ffff:ffff:ffff:ffff
215fca3:d6::/32fca3:d6:ffff:ffff:ffff:ffff:ffff:ffff
216fca3:d7::/32fca3:d7:ffff:ffff:ffff:ffff:ffff:ffff
217fca3:d8::/32fca3:d8:ffff:ffff:ffff:ffff:ffff:ffff
218fca3:d9::/32fca3:d9:ffff:ffff:ffff:ffff:ffff:ffff
219fca3:da::/32fca3:da:ffff:ffff:ffff:ffff:ffff:ffff
220fca3:db::/32fca3:db:ffff:ffff:ffff:ffff:ffff:ffff
221fca3:dc::/32fca3:dc:ffff:ffff:ffff:ffff:ffff:ffff
222fca3:dd::/32fca3:dd:ffff:ffff:ffff:ffff:ffff:ffff
223fca3:de::/32fca3:de:ffff:ffff:ffff:ffff:ffff:ffff
224fca3:df::/32fca3:df:ffff:ffff:ffff:ffff:ffff:ffff
225fca3:e0::/32fca3:e0:ffff:ffff:ffff:ffff:ffff:ffff
226fca3:e1::/32fca3:e1:ffff:ffff:ffff:ffff:ffff:ffff
227fca3:e2::/32fca3:e2:ffff:ffff:ffff:ffff:ffff:ffff
228fca3:e3::/32fca3:e3:ffff:ffff:ffff:ffff:ffff:ffff
229fca3:e4::/32fca3:e4:ffff:ffff:ffff:ffff:ffff:ffff
230fca3:e5::/32fca3:e5:ffff:ffff:ffff:ffff:ffff:ffff
231fca3:e6::/32fca3:e6:ffff:ffff:ffff:ffff:ffff:ffff
232fca3:e7::/32fca3:e7:ffff:ffff:ffff:ffff:ffff:ffff
233fca3:e8::/32fca3:e8:ffff:ffff:ffff:ffff:ffff:ffff
234fca3:e9::/32fca3:e9:ffff:ffff:ffff:ffff:ffff:ffff
235fca3:ea::/32fca3:ea:ffff:ffff:ffff:ffff:ffff:ffff
236fca3:eb::/32fca3:eb:ffff:ffff:ffff:ffff:ffff:ffff
237fca3:ec::/32fca3:ec:ffff:ffff:ffff:ffff:ffff:ffff
238fca3:ed::/32fca3:ed:ffff:ffff:ffff:ffff:ffff:ffff
239fca3:ee::/32fca3:ee:ffff:ffff:ffff:ffff:ffff:ffff
240fca3:ef::/32fca3:ef:ffff:ffff:ffff:ffff:ffff:ffff
241fca3:f0::/32fca3:f0:ffff:ffff:ffff:ffff:ffff:ffff
242fca3:f1::/32fca3:f1:ffff:ffff:ffff:ffff:ffff:ffff
243fca3:f2::/32fca3:f2:ffff:ffff:ffff:ffff:ffff:ffff
244fca3:f3::/32fca3:f3:ffff:ffff:ffff:ffff:ffff:ffff
245fca3:f4::/32fca3:f4:ffff:ffff:ffff:ffff:ffff:ffff
246fca3:f5::/32fca3:f5:ffff:ffff:ffff:ffff:ffff:ffff
247fca3:f6::/32fca3:f6:ffff:ffff:ffff:ffff:ffff:ffff
248fca3:f7::/32fca3:f7:ffff:ffff:ffff:ffff:ffff:ffff
249fca3:f8::/32fca3:f8:ffff:ffff:ffff:ffff:ffff:ffff
250fca3:f9::/32fca3:f9:ffff:ffff:ffff:ffff:ffff:ffff
251fca3:fa::/32fca3:fa:ffff:ffff:ffff:ffff:ffff:ffff
252fca3:fb::/32fca3:fb:ffff:ffff:ffff:ffff:ffff:ffff
253fca3:fc::/32fca3:fc:ffff:ffff:ffff:ffff:ffff:ffff
254fca3:fd::/32fca3:fd:ffff:ffff:ffff:ffff:ffff:ffff
255fca3:fe::/32fca3:fe:ffff:ffff:ffff:ffff:ffff:ffff
256fca3:ff::/32fca3: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.