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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/11
Addresses2^117
/64 networks2^53
Network
fca0::/11
First address
fca0::
Last address
fcbf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
166,153,499,473,114,484,112,975,882,535,043,072 (2^117)
/64 networks (LANs)
9,007,199,254,740,992 (2^53)
Full form
fca0:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zones
a.c.f.ip6.arpa
b.c.f.ip6.arpa
/11 is not on a 4-bit boundary, so it takes 2 /12 zones.
Split into smaller subnets/20
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/20 (512)/24 (8,192)

fca0::/11 makes 512 subnets of /20; the first 256 are listed.

Subnets
#SubnetLast address
1fca0::/20fca0:fff:ffff:ffff:ffff:ffff:ffff:ffff
2fca0:1000::/20fca0:1fff:ffff:ffff:ffff:ffff:ffff:ffff
3fca0:2000::/20fca0:2fff:ffff:ffff:ffff:ffff:ffff:ffff
4fca0:3000::/20fca0:3fff:ffff:ffff:ffff:ffff:ffff:ffff
5fca0:4000::/20fca0:4fff:ffff:ffff:ffff:ffff:ffff:ffff
6fca0:5000::/20fca0:5fff:ffff:ffff:ffff:ffff:ffff:ffff
7fca0:6000::/20fca0:6fff:ffff:ffff:ffff:ffff:ffff:ffff
8fca0:7000::/20fca0:7fff:ffff:ffff:ffff:ffff:ffff:ffff
9fca0:8000::/20fca0:8fff:ffff:ffff:ffff:ffff:ffff:ffff
10fca0:9000::/20fca0:9fff:ffff:ffff:ffff:ffff:ffff:ffff
11fca0:a000::/20fca0:afff:ffff:ffff:ffff:ffff:ffff:ffff
12fca0:b000::/20fca0:bfff:ffff:ffff:ffff:ffff:ffff:ffff
13fca0:c000::/20fca0:cfff:ffff:ffff:ffff:ffff:ffff:ffff
14fca0:d000::/20fca0:dfff:ffff:ffff:ffff:ffff:ffff:ffff
15fca0:e000::/20fca0:efff:ffff:ffff:ffff:ffff:ffff:ffff
16fca0:f000::/20fca0:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17fca1::/20fca1:fff:ffff:ffff:ffff:ffff:ffff:ffff
18fca1:1000::/20fca1:1fff:ffff:ffff:ffff:ffff:ffff:ffff
19fca1:2000::/20fca1:2fff:ffff:ffff:ffff:ffff:ffff:ffff
20fca1:3000::/20fca1:3fff:ffff:ffff:ffff:ffff:ffff:ffff
21fca1:4000::/20fca1:4fff:ffff:ffff:ffff:ffff:ffff:ffff
22fca1:5000::/20fca1:5fff:ffff:ffff:ffff:ffff:ffff:ffff
23fca1:6000::/20fca1:6fff:ffff:ffff:ffff:ffff:ffff:ffff
24fca1:7000::/20fca1:7fff:ffff:ffff:ffff:ffff:ffff:ffff
25fca1:8000::/20fca1:8fff:ffff:ffff:ffff:ffff:ffff:ffff
26fca1:9000::/20fca1:9fff:ffff:ffff:ffff:ffff:ffff:ffff
27fca1:a000::/20fca1:afff:ffff:ffff:ffff:ffff:ffff:ffff
28fca1:b000::/20fca1:bfff:ffff:ffff:ffff:ffff:ffff:ffff
29fca1:c000::/20fca1:cfff:ffff:ffff:ffff:ffff:ffff:ffff
30fca1:d000::/20fca1:dfff:ffff:ffff:ffff:ffff:ffff:ffff
31fca1:e000::/20fca1:efff:ffff:ffff:ffff:ffff:ffff:ffff
32fca1:f000::/20fca1:ffff:ffff:ffff:ffff:ffff:ffff:ffff
33fca2::/20fca2:fff:ffff:ffff:ffff:ffff:ffff:ffff
34fca2:1000::/20fca2:1fff:ffff:ffff:ffff:ffff:ffff:ffff
35fca2:2000::/20fca2:2fff:ffff:ffff:ffff:ffff:ffff:ffff
36fca2:3000::/20fca2:3fff:ffff:ffff:ffff:ffff:ffff:ffff
37fca2:4000::/20fca2:4fff:ffff:ffff:ffff:ffff:ffff:ffff
38fca2:5000::/20fca2:5fff:ffff:ffff:ffff:ffff:ffff:ffff
39fca2:6000::/20fca2:6fff:ffff:ffff:ffff:ffff:ffff:ffff
40fca2:7000::/20fca2:7fff:ffff:ffff:ffff:ffff:ffff:ffff
41fca2:8000::/20fca2:8fff:ffff:ffff:ffff:ffff:ffff:ffff
42fca2:9000::/20fca2:9fff:ffff:ffff:ffff:ffff:ffff:ffff
43fca2:a000::/20fca2:afff:ffff:ffff:ffff:ffff:ffff:ffff
44fca2:b000::/20fca2:bfff:ffff:ffff:ffff:ffff:ffff:ffff
45fca2:c000::/20fca2:cfff:ffff:ffff:ffff:ffff:ffff:ffff
46fca2:d000::/20fca2:dfff:ffff:ffff:ffff:ffff:ffff:ffff
47fca2:e000::/20fca2:efff:ffff:ffff:ffff:ffff:ffff:ffff
48fca2:f000::/20fca2:ffff:ffff:ffff:ffff:ffff:ffff:ffff
49fca3::/20fca3:fff:ffff:ffff:ffff:ffff:ffff:ffff
50fca3:1000::/20fca3:1fff:ffff:ffff:ffff:ffff:ffff:ffff
51fca3:2000::/20fca3:2fff:ffff:ffff:ffff:ffff:ffff:ffff
52fca3:3000::/20fca3:3fff:ffff:ffff:ffff:ffff:ffff:ffff
53fca3:4000::/20fca3:4fff:ffff:ffff:ffff:ffff:ffff:ffff
54fca3:5000::/20fca3:5fff:ffff:ffff:ffff:ffff:ffff:ffff
55fca3:6000::/20fca3:6fff:ffff:ffff:ffff:ffff:ffff:ffff
56fca3:7000::/20fca3:7fff:ffff:ffff:ffff:ffff:ffff:ffff
57fca3:8000::/20fca3:8fff:ffff:ffff:ffff:ffff:ffff:ffff
58fca3:9000::/20fca3:9fff:ffff:ffff:ffff:ffff:ffff:ffff
59fca3:a000::/20fca3:afff:ffff:ffff:ffff:ffff:ffff:ffff
60fca3:b000::/20fca3:bfff:ffff:ffff:ffff:ffff:ffff:ffff
61fca3:c000::/20fca3:cfff:ffff:ffff:ffff:ffff:ffff:ffff
62fca3:d000::/20fca3:dfff:ffff:ffff:ffff:ffff:ffff:ffff
63fca3:e000::/20fca3:efff:ffff:ffff:ffff:ffff:ffff:ffff
64fca3:f000::/20fca3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
65fca4::/20fca4:fff:ffff:ffff:ffff:ffff:ffff:ffff
66fca4:1000::/20fca4:1fff:ffff:ffff:ffff:ffff:ffff:ffff
67fca4:2000::/20fca4:2fff:ffff:ffff:ffff:ffff:ffff:ffff
68fca4:3000::/20fca4:3fff:ffff:ffff:ffff:ffff:ffff:ffff
69fca4:4000::/20fca4:4fff:ffff:ffff:ffff:ffff:ffff:ffff
70fca4:5000::/20fca4:5fff:ffff:ffff:ffff:ffff:ffff:ffff
71fca4:6000::/20fca4:6fff:ffff:ffff:ffff:ffff:ffff:ffff
72fca4:7000::/20fca4:7fff:ffff:ffff:ffff:ffff:ffff:ffff
73fca4:8000::/20fca4:8fff:ffff:ffff:ffff:ffff:ffff:ffff
74fca4:9000::/20fca4:9fff:ffff:ffff:ffff:ffff:ffff:ffff
75fca4:a000::/20fca4:afff:ffff:ffff:ffff:ffff:ffff:ffff
76fca4:b000::/20fca4:bfff:ffff:ffff:ffff:ffff:ffff:ffff
77fca4:c000::/20fca4:cfff:ffff:ffff:ffff:ffff:ffff:ffff
78fca4:d000::/20fca4:dfff:ffff:ffff:ffff:ffff:ffff:ffff
79fca4:e000::/20fca4:efff:ffff:ffff:ffff:ffff:ffff:ffff
80fca4:f000::/20fca4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
81fca5::/20fca5:fff:ffff:ffff:ffff:ffff:ffff:ffff
82fca5:1000::/20fca5:1fff:ffff:ffff:ffff:ffff:ffff:ffff
83fca5:2000::/20fca5:2fff:ffff:ffff:ffff:ffff:ffff:ffff
84fca5:3000::/20fca5:3fff:ffff:ffff:ffff:ffff:ffff:ffff
85fca5:4000::/20fca5:4fff:ffff:ffff:ffff:ffff:ffff:ffff
86fca5:5000::/20fca5:5fff:ffff:ffff:ffff:ffff:ffff:ffff
87fca5:6000::/20fca5:6fff:ffff:ffff:ffff:ffff:ffff:ffff
88fca5:7000::/20fca5:7fff:ffff:ffff:ffff:ffff:ffff:ffff
89fca5:8000::/20fca5:8fff:ffff:ffff:ffff:ffff:ffff:ffff
90fca5:9000::/20fca5:9fff:ffff:ffff:ffff:ffff:ffff:ffff
91fca5:a000::/20fca5:afff:ffff:ffff:ffff:ffff:ffff:ffff
92fca5:b000::/20fca5:bfff:ffff:ffff:ffff:ffff:ffff:ffff
93fca5:c000::/20fca5:cfff:ffff:ffff:ffff:ffff:ffff:ffff
94fca5:d000::/20fca5:dfff:ffff:ffff:ffff:ffff:ffff:ffff
95fca5:e000::/20fca5:efff:ffff:ffff:ffff:ffff:ffff:ffff
96fca5:f000::/20fca5:ffff:ffff:ffff:ffff:ffff:ffff:ffff
97fca6::/20fca6:fff:ffff:ffff:ffff:ffff:ffff:ffff
98fca6:1000::/20fca6:1fff:ffff:ffff:ffff:ffff:ffff:ffff
99fca6:2000::/20fca6:2fff:ffff:ffff:ffff:ffff:ffff:ffff
100fca6:3000::/20fca6:3fff:ffff:ffff:ffff:ffff:ffff:ffff
101fca6:4000::/20fca6:4fff:ffff:ffff:ffff:ffff:ffff:ffff
102fca6:5000::/20fca6:5fff:ffff:ffff:ffff:ffff:ffff:ffff
103fca6:6000::/20fca6:6fff:ffff:ffff:ffff:ffff:ffff:ffff
104fca6:7000::/20fca6:7fff:ffff:ffff:ffff:ffff:ffff:ffff
105fca6:8000::/20fca6:8fff:ffff:ffff:ffff:ffff:ffff:ffff
106fca6:9000::/20fca6:9fff:ffff:ffff:ffff:ffff:ffff:ffff
107fca6:a000::/20fca6:afff:ffff:ffff:ffff:ffff:ffff:ffff
108fca6:b000::/20fca6:bfff:ffff:ffff:ffff:ffff:ffff:ffff
109fca6:c000::/20fca6:cfff:ffff:ffff:ffff:ffff:ffff:ffff
110fca6:d000::/20fca6:dfff:ffff:ffff:ffff:ffff:ffff:ffff
111fca6:e000::/20fca6:efff:ffff:ffff:ffff:ffff:ffff:ffff
112fca6:f000::/20fca6:ffff:ffff:ffff:ffff:ffff:ffff:ffff
113fca7::/20fca7:fff:ffff:ffff:ffff:ffff:ffff:ffff
114fca7:1000::/20fca7:1fff:ffff:ffff:ffff:ffff:ffff:ffff
115fca7:2000::/20fca7:2fff:ffff:ffff:ffff:ffff:ffff:ffff
116fca7:3000::/20fca7:3fff:ffff:ffff:ffff:ffff:ffff:ffff
117fca7:4000::/20fca7:4fff:ffff:ffff:ffff:ffff:ffff:ffff
118fca7:5000::/20fca7:5fff:ffff:ffff:ffff:ffff:ffff:ffff
119fca7:6000::/20fca7:6fff:ffff:ffff:ffff:ffff:ffff:ffff
120fca7:7000::/20fca7:7fff:ffff:ffff:ffff:ffff:ffff:ffff
121fca7:8000::/20fca7:8fff:ffff:ffff:ffff:ffff:ffff:ffff
122fca7:9000::/20fca7:9fff:ffff:ffff:ffff:ffff:ffff:ffff
123fca7:a000::/20fca7:afff:ffff:ffff:ffff:ffff:ffff:ffff
124fca7:b000::/20fca7:bfff:ffff:ffff:ffff:ffff:ffff:ffff
125fca7:c000::/20fca7:cfff:ffff:ffff:ffff:ffff:ffff:ffff
126fca7:d000::/20fca7:dfff:ffff:ffff:ffff:ffff:ffff:ffff
127fca7:e000::/20fca7:efff:ffff:ffff:ffff:ffff:ffff:ffff
128fca7:f000::/20fca7:ffff:ffff:ffff:ffff:ffff:ffff:ffff
129fca8::/20fca8:fff:ffff:ffff:ffff:ffff:ffff:ffff
130fca8:1000::/20fca8:1fff:ffff:ffff:ffff:ffff:ffff:ffff
131fca8:2000::/20fca8:2fff:ffff:ffff:ffff:ffff:ffff:ffff
132fca8:3000::/20fca8:3fff:ffff:ffff:ffff:ffff:ffff:ffff
133fca8:4000::/20fca8:4fff:ffff:ffff:ffff:ffff:ffff:ffff
134fca8:5000::/20fca8:5fff:ffff:ffff:ffff:ffff:ffff:ffff
135fca8:6000::/20fca8:6fff:ffff:ffff:ffff:ffff:ffff:ffff
136fca8:7000::/20fca8:7fff:ffff:ffff:ffff:ffff:ffff:ffff
137fca8:8000::/20fca8:8fff:ffff:ffff:ffff:ffff:ffff:ffff
138fca8:9000::/20fca8:9fff:ffff:ffff:ffff:ffff:ffff:ffff
139fca8:a000::/20fca8:afff:ffff:ffff:ffff:ffff:ffff:ffff
140fca8:b000::/20fca8:bfff:ffff:ffff:ffff:ffff:ffff:ffff
141fca8:c000::/20fca8:cfff:ffff:ffff:ffff:ffff:ffff:ffff
142fca8:d000::/20fca8:dfff:ffff:ffff:ffff:ffff:ffff:ffff
143fca8:e000::/20fca8:efff:ffff:ffff:ffff:ffff:ffff:ffff
144fca8:f000::/20fca8:ffff:ffff:ffff:ffff:ffff:ffff:ffff
145fca9::/20fca9:fff:ffff:ffff:ffff:ffff:ffff:ffff
146fca9:1000::/20fca9:1fff:ffff:ffff:ffff:ffff:ffff:ffff
147fca9:2000::/20fca9:2fff:ffff:ffff:ffff:ffff:ffff:ffff
148fca9:3000::/20fca9:3fff:ffff:ffff:ffff:ffff:ffff:ffff
149fca9:4000::/20fca9:4fff:ffff:ffff:ffff:ffff:ffff:ffff
150fca9:5000::/20fca9:5fff:ffff:ffff:ffff:ffff:ffff:ffff
151fca9:6000::/20fca9:6fff:ffff:ffff:ffff:ffff:ffff:ffff
152fca9:7000::/20fca9:7fff:ffff:ffff:ffff:ffff:ffff:ffff
153fca9:8000::/20fca9:8fff:ffff:ffff:ffff:ffff:ffff:ffff
154fca9:9000::/20fca9:9fff:ffff:ffff:ffff:ffff:ffff:ffff
155fca9:a000::/20fca9:afff:ffff:ffff:ffff:ffff:ffff:ffff
156fca9:b000::/20fca9:bfff:ffff:ffff:ffff:ffff:ffff:ffff
157fca9:c000::/20fca9:cfff:ffff:ffff:ffff:ffff:ffff:ffff
158fca9:d000::/20fca9:dfff:ffff:ffff:ffff:ffff:ffff:ffff
159fca9:e000::/20fca9:efff:ffff:ffff:ffff:ffff:ffff:ffff
160fca9:f000::/20fca9:ffff:ffff:ffff:ffff:ffff:ffff:ffff
161fcaa::/20fcaa:fff:ffff:ffff:ffff:ffff:ffff:ffff
162fcaa:1000::/20fcaa:1fff:ffff:ffff:ffff:ffff:ffff:ffff
163fcaa:2000::/20fcaa:2fff:ffff:ffff:ffff:ffff:ffff:ffff
164fcaa:3000::/20fcaa:3fff:ffff:ffff:ffff:ffff:ffff:ffff
165fcaa:4000::/20fcaa:4fff:ffff:ffff:ffff:ffff:ffff:ffff
166fcaa:5000::/20fcaa:5fff:ffff:ffff:ffff:ffff:ffff:ffff
167fcaa:6000::/20fcaa:6fff:ffff:ffff:ffff:ffff:ffff:ffff
168fcaa:7000::/20fcaa:7fff:ffff:ffff:ffff:ffff:ffff:ffff
169fcaa:8000::/20fcaa:8fff:ffff:ffff:ffff:ffff:ffff:ffff
170fcaa:9000::/20fcaa:9fff:ffff:ffff:ffff:ffff:ffff:ffff
171fcaa:a000::/20fcaa:afff:ffff:ffff:ffff:ffff:ffff:ffff
172fcaa:b000::/20fcaa:bfff:ffff:ffff:ffff:ffff:ffff:ffff
173fcaa:c000::/20fcaa:cfff:ffff:ffff:ffff:ffff:ffff:ffff
174fcaa:d000::/20fcaa:dfff:ffff:ffff:ffff:ffff:ffff:ffff
175fcaa:e000::/20fcaa:efff:ffff:ffff:ffff:ffff:ffff:ffff
176fcaa:f000::/20fcaa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
177fcab::/20fcab:fff:ffff:ffff:ffff:ffff:ffff:ffff
178fcab:1000::/20fcab:1fff:ffff:ffff:ffff:ffff:ffff:ffff
179fcab:2000::/20fcab:2fff:ffff:ffff:ffff:ffff:ffff:ffff
180fcab:3000::/20fcab:3fff:ffff:ffff:ffff:ffff:ffff:ffff
181fcab:4000::/20fcab:4fff:ffff:ffff:ffff:ffff:ffff:ffff
182fcab:5000::/20fcab:5fff:ffff:ffff:ffff:ffff:ffff:ffff
183fcab:6000::/20fcab:6fff:ffff:ffff:ffff:ffff:ffff:ffff
184fcab:7000::/20fcab:7fff:ffff:ffff:ffff:ffff:ffff:ffff
185fcab:8000::/20fcab:8fff:ffff:ffff:ffff:ffff:ffff:ffff
186fcab:9000::/20fcab:9fff:ffff:ffff:ffff:ffff:ffff:ffff
187fcab:a000::/20fcab:afff:ffff:ffff:ffff:ffff:ffff:ffff
188fcab:b000::/20fcab:bfff:ffff:ffff:ffff:ffff:ffff:ffff
189fcab:c000::/20fcab:cfff:ffff:ffff:ffff:ffff:ffff:ffff
190fcab:d000::/20fcab:dfff:ffff:ffff:ffff:ffff:ffff:ffff
191fcab:e000::/20fcab:efff:ffff:ffff:ffff:ffff:ffff:ffff
192fcab:f000::/20fcab:ffff:ffff:ffff:ffff:ffff:ffff:ffff
193fcac::/20fcac:fff:ffff:ffff:ffff:ffff:ffff:ffff
194fcac:1000::/20fcac:1fff:ffff:ffff:ffff:ffff:ffff:ffff
195fcac:2000::/20fcac:2fff:ffff:ffff:ffff:ffff:ffff:ffff
196fcac:3000::/20fcac:3fff:ffff:ffff:ffff:ffff:ffff:ffff
197fcac:4000::/20fcac:4fff:ffff:ffff:ffff:ffff:ffff:ffff
198fcac:5000::/20fcac:5fff:ffff:ffff:ffff:ffff:ffff:ffff
199fcac:6000::/20fcac:6fff:ffff:ffff:ffff:ffff:ffff:ffff
200fcac:7000::/20fcac:7fff:ffff:ffff:ffff:ffff:ffff:ffff
201fcac:8000::/20fcac:8fff:ffff:ffff:ffff:ffff:ffff:ffff
202fcac:9000::/20fcac:9fff:ffff:ffff:ffff:ffff:ffff:ffff
203fcac:a000::/20fcac:afff:ffff:ffff:ffff:ffff:ffff:ffff
204fcac:b000::/20fcac:bfff:ffff:ffff:ffff:ffff:ffff:ffff
205fcac:c000::/20fcac:cfff:ffff:ffff:ffff:ffff:ffff:ffff
206fcac:d000::/20fcac:dfff:ffff:ffff:ffff:ffff:ffff:ffff
207fcac:e000::/20fcac:efff:ffff:ffff:ffff:ffff:ffff:ffff
208fcac:f000::/20fcac:ffff:ffff:ffff:ffff:ffff:ffff:ffff
209fcad::/20fcad:fff:ffff:ffff:ffff:ffff:ffff:ffff
210fcad:1000::/20fcad:1fff:ffff:ffff:ffff:ffff:ffff:ffff
211fcad:2000::/20fcad:2fff:ffff:ffff:ffff:ffff:ffff:ffff
212fcad:3000::/20fcad:3fff:ffff:ffff:ffff:ffff:ffff:ffff
213fcad:4000::/20fcad:4fff:ffff:ffff:ffff:ffff:ffff:ffff
214fcad:5000::/20fcad:5fff:ffff:ffff:ffff:ffff:ffff:ffff
215fcad:6000::/20fcad:6fff:ffff:ffff:ffff:ffff:ffff:ffff
216fcad:7000::/20fcad:7fff:ffff:ffff:ffff:ffff:ffff:ffff
217fcad:8000::/20fcad:8fff:ffff:ffff:ffff:ffff:ffff:ffff
218fcad:9000::/20fcad:9fff:ffff:ffff:ffff:ffff:ffff:ffff
219fcad:a000::/20fcad:afff:ffff:ffff:ffff:ffff:ffff:ffff
220fcad:b000::/20fcad:bfff:ffff:ffff:ffff:ffff:ffff:ffff
221fcad:c000::/20fcad:cfff:ffff:ffff:ffff:ffff:ffff:ffff
222fcad:d000::/20fcad:dfff:ffff:ffff:ffff:ffff:ffff:ffff
223fcad:e000::/20fcad:efff:ffff:ffff:ffff:ffff:ffff:ffff
224fcad:f000::/20fcad:ffff:ffff:ffff:ffff:ffff:ffff:ffff
225fcae::/20fcae:fff:ffff:ffff:ffff:ffff:ffff:ffff
226fcae:1000::/20fcae:1fff:ffff:ffff:ffff:ffff:ffff:ffff
227fcae:2000::/20fcae:2fff:ffff:ffff:ffff:ffff:ffff:ffff
228fcae:3000::/20fcae:3fff:ffff:ffff:ffff:ffff:ffff:ffff
229fcae:4000::/20fcae:4fff:ffff:ffff:ffff:ffff:ffff:ffff
230fcae:5000::/20fcae:5fff:ffff:ffff:ffff:ffff:ffff:ffff
231fcae:6000::/20fcae:6fff:ffff:ffff:ffff:ffff:ffff:ffff
232fcae:7000::/20fcae:7fff:ffff:ffff:ffff:ffff:ffff:ffff
233fcae:8000::/20fcae:8fff:ffff:ffff:ffff:ffff:ffff:ffff
234fcae:9000::/20fcae:9fff:ffff:ffff:ffff:ffff:ffff:ffff
235fcae:a000::/20fcae:afff:ffff:ffff:ffff:ffff:ffff:ffff
236fcae:b000::/20fcae:bfff:ffff:ffff:ffff:ffff:ffff:ffff
237fcae:c000::/20fcae:cfff:ffff:ffff:ffff:ffff:ffff:ffff
238fcae:d000::/20fcae:dfff:ffff:ffff:ffff:ffff:ffff:ffff
239fcae:e000::/20fcae:efff:ffff:ffff:ffff:ffff:ffff:ffff
240fcae:f000::/20fcae:ffff:ffff:ffff:ffff:ffff:ffff:ffff
241fcaf::/20fcaf:fff:ffff:ffff:ffff:ffff:ffff:ffff
242fcaf:1000::/20fcaf:1fff:ffff:ffff:ffff:ffff:ffff:ffff
243fcaf:2000::/20fcaf:2fff:ffff:ffff:ffff:ffff:ffff:ffff
244fcaf:3000::/20fcaf:3fff:ffff:ffff:ffff:ffff:ffff:ffff
245fcaf:4000::/20fcaf:4fff:ffff:ffff:ffff:ffff:ffff:ffff
246fcaf:5000::/20fcaf:5fff:ffff:ffff:ffff:ffff:ffff:ffff
247fcaf:6000::/20fcaf:6fff:ffff:ffff:ffff:ffff:ffff:ffff
248fcaf:7000::/20fcaf:7fff:ffff:ffff:ffff:ffff:ffff:ffff
249fcaf:8000::/20fcaf:8fff:ffff:ffff:ffff:ffff:ffff:ffff
250fcaf:9000::/20fcaf:9fff:ffff:ffff:ffff:ffff:ffff:ffff
251fcaf:a000::/20fcaf:afff:ffff:ffff:ffff:ffff:ffff:ffff
252fcaf:b000::/20fcaf:bfff:ffff:ffff:ffff:ffff:ffff:ffff
253fcaf:c000::/20fcaf:cfff:ffff:ffff:ffff:ffff:ffff:ffff
254fcaf:d000::/20fcaf:dfff:ffff:ffff:ffff:ffff:ffff:ffff
255fcaf:e000::/20fcaf:efff:ffff:ffff:ffff:ffff:ffff:ffff
256fcaf:f000::/20fcaf: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.