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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/10
Addresses2^118
/64 networks2^54
Network
fc00::/10
First address
fc00::
Last address
fc3f:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
332,306,998,946,228,968,225,951,765,070,086,144 (2^118)
/64 networks (LANs)
18,014,398,509,481,984 (2^54)
Full form
fc00:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zones
0.c.f.ip6.arpa
1.c.f.ip6.arpa
2.c.f.ip6.arpa
3.c.f.ip6.arpa
/10 is not on a 4-bit boundary, so it takes 4 /12 zones.
Split into smaller subnets/20
/11 (2)/12 (4)/13 (8)/14 (16)/16 (64)/20 (1,024)/24 (16,384)

fc00::/10 makes 1,024 subnets of /20; the first 256 are listed.

Subnets
#SubnetLast address
1fc00::/20fc00:fff:ffff:ffff:ffff:ffff:ffff:ffff
2fc00:1000::/20fc00:1fff:ffff:ffff:ffff:ffff:ffff:ffff
3fc00:2000::/20fc00:2fff:ffff:ffff:ffff:ffff:ffff:ffff
4fc00:3000::/20fc00:3fff:ffff:ffff:ffff:ffff:ffff:ffff
5fc00:4000::/20fc00:4fff:ffff:ffff:ffff:ffff:ffff:ffff
6fc00:5000::/20fc00:5fff:ffff:ffff:ffff:ffff:ffff:ffff
7fc00:6000::/20fc00:6fff:ffff:ffff:ffff:ffff:ffff:ffff
8fc00:7000::/20fc00:7fff:ffff:ffff:ffff:ffff:ffff:ffff
9fc00:8000::/20fc00:8fff:ffff:ffff:ffff:ffff:ffff:ffff
10fc00:9000::/20fc00:9fff:ffff:ffff:ffff:ffff:ffff:ffff
11fc00:a000::/20fc00:afff:ffff:ffff:ffff:ffff:ffff:ffff
12fc00:b000::/20fc00:bfff:ffff:ffff:ffff:ffff:ffff:ffff
13fc00:c000::/20fc00:cfff:ffff:ffff:ffff:ffff:ffff:ffff
14fc00:d000::/20fc00:dfff:ffff:ffff:ffff:ffff:ffff:ffff
15fc00:e000::/20fc00:efff:ffff:ffff:ffff:ffff:ffff:ffff
16fc00:f000::/20fc00:ffff:ffff:ffff:ffff:ffff:ffff:ffff
17fc01::/20fc01:fff:ffff:ffff:ffff:ffff:ffff:ffff
18fc01:1000::/20fc01:1fff:ffff:ffff:ffff:ffff:ffff:ffff
19fc01:2000::/20fc01:2fff:ffff:ffff:ffff:ffff:ffff:ffff
20fc01:3000::/20fc01:3fff:ffff:ffff:ffff:ffff:ffff:ffff
21fc01:4000::/20fc01:4fff:ffff:ffff:ffff:ffff:ffff:ffff
22fc01:5000::/20fc01:5fff:ffff:ffff:ffff:ffff:ffff:ffff
23fc01:6000::/20fc01:6fff:ffff:ffff:ffff:ffff:ffff:ffff
24fc01:7000::/20fc01:7fff:ffff:ffff:ffff:ffff:ffff:ffff
25fc01:8000::/20fc01:8fff:ffff:ffff:ffff:ffff:ffff:ffff
26fc01:9000::/20fc01:9fff:ffff:ffff:ffff:ffff:ffff:ffff
27fc01:a000::/20fc01:afff:ffff:ffff:ffff:ffff:ffff:ffff
28fc01:b000::/20fc01:bfff:ffff:ffff:ffff:ffff:ffff:ffff
29fc01:c000::/20fc01:cfff:ffff:ffff:ffff:ffff:ffff:ffff
30fc01:d000::/20fc01:dfff:ffff:ffff:ffff:ffff:ffff:ffff
31fc01:e000::/20fc01:efff:ffff:ffff:ffff:ffff:ffff:ffff
32fc01:f000::/20fc01:ffff:ffff:ffff:ffff:ffff:ffff:ffff
33fc02::/20fc02:fff:ffff:ffff:ffff:ffff:ffff:ffff
34fc02:1000::/20fc02:1fff:ffff:ffff:ffff:ffff:ffff:ffff
35fc02:2000::/20fc02:2fff:ffff:ffff:ffff:ffff:ffff:ffff
36fc02:3000::/20fc02:3fff:ffff:ffff:ffff:ffff:ffff:ffff
37fc02:4000::/20fc02:4fff:ffff:ffff:ffff:ffff:ffff:ffff
38fc02:5000::/20fc02:5fff:ffff:ffff:ffff:ffff:ffff:ffff
39fc02:6000::/20fc02:6fff:ffff:ffff:ffff:ffff:ffff:ffff
40fc02:7000::/20fc02:7fff:ffff:ffff:ffff:ffff:ffff:ffff
41fc02:8000::/20fc02:8fff:ffff:ffff:ffff:ffff:ffff:ffff
42fc02:9000::/20fc02:9fff:ffff:ffff:ffff:ffff:ffff:ffff
43fc02:a000::/20fc02:afff:ffff:ffff:ffff:ffff:ffff:ffff
44fc02:b000::/20fc02:bfff:ffff:ffff:ffff:ffff:ffff:ffff
45fc02:c000::/20fc02:cfff:ffff:ffff:ffff:ffff:ffff:ffff
46fc02:d000::/20fc02:dfff:ffff:ffff:ffff:ffff:ffff:ffff
47fc02:e000::/20fc02:efff:ffff:ffff:ffff:ffff:ffff:ffff
48fc02:f000::/20fc02:ffff:ffff:ffff:ffff:ffff:ffff:ffff
49fc03::/20fc03:fff:ffff:ffff:ffff:ffff:ffff:ffff
50fc03:1000::/20fc03:1fff:ffff:ffff:ffff:ffff:ffff:ffff
51fc03:2000::/20fc03:2fff:ffff:ffff:ffff:ffff:ffff:ffff
52fc03:3000::/20fc03:3fff:ffff:ffff:ffff:ffff:ffff:ffff
53fc03:4000::/20fc03:4fff:ffff:ffff:ffff:ffff:ffff:ffff
54fc03:5000::/20fc03:5fff:ffff:ffff:ffff:ffff:ffff:ffff
55fc03:6000::/20fc03:6fff:ffff:ffff:ffff:ffff:ffff:ffff
56fc03:7000::/20fc03:7fff:ffff:ffff:ffff:ffff:ffff:ffff
57fc03:8000::/20fc03:8fff:ffff:ffff:ffff:ffff:ffff:ffff
58fc03:9000::/20fc03:9fff:ffff:ffff:ffff:ffff:ffff:ffff
59fc03:a000::/20fc03:afff:ffff:ffff:ffff:ffff:ffff:ffff
60fc03:b000::/20fc03:bfff:ffff:ffff:ffff:ffff:ffff:ffff
61fc03:c000::/20fc03:cfff:ffff:ffff:ffff:ffff:ffff:ffff
62fc03:d000::/20fc03:dfff:ffff:ffff:ffff:ffff:ffff:ffff
63fc03:e000::/20fc03:efff:ffff:ffff:ffff:ffff:ffff:ffff
64fc03:f000::/20fc03:ffff:ffff:ffff:ffff:ffff:ffff:ffff
65fc04::/20fc04:fff:ffff:ffff:ffff:ffff:ffff:ffff
66fc04:1000::/20fc04:1fff:ffff:ffff:ffff:ffff:ffff:ffff
67fc04:2000::/20fc04:2fff:ffff:ffff:ffff:ffff:ffff:ffff
68fc04:3000::/20fc04:3fff:ffff:ffff:ffff:ffff:ffff:ffff
69fc04:4000::/20fc04:4fff:ffff:ffff:ffff:ffff:ffff:ffff
70fc04:5000::/20fc04:5fff:ffff:ffff:ffff:ffff:ffff:ffff
71fc04:6000::/20fc04:6fff:ffff:ffff:ffff:ffff:ffff:ffff
72fc04:7000::/20fc04:7fff:ffff:ffff:ffff:ffff:ffff:ffff
73fc04:8000::/20fc04:8fff:ffff:ffff:ffff:ffff:ffff:ffff
74fc04:9000::/20fc04:9fff:ffff:ffff:ffff:ffff:ffff:ffff
75fc04:a000::/20fc04:afff:ffff:ffff:ffff:ffff:ffff:ffff
76fc04:b000::/20fc04:bfff:ffff:ffff:ffff:ffff:ffff:ffff
77fc04:c000::/20fc04:cfff:ffff:ffff:ffff:ffff:ffff:ffff
78fc04:d000::/20fc04:dfff:ffff:ffff:ffff:ffff:ffff:ffff
79fc04:e000::/20fc04:efff:ffff:ffff:ffff:ffff:ffff:ffff
80fc04:f000::/20fc04:ffff:ffff:ffff:ffff:ffff:ffff:ffff
81fc05::/20fc05:fff:ffff:ffff:ffff:ffff:ffff:ffff
82fc05:1000::/20fc05:1fff:ffff:ffff:ffff:ffff:ffff:ffff
83fc05:2000::/20fc05:2fff:ffff:ffff:ffff:ffff:ffff:ffff
84fc05:3000::/20fc05:3fff:ffff:ffff:ffff:ffff:ffff:ffff
85fc05:4000::/20fc05:4fff:ffff:ffff:ffff:ffff:ffff:ffff
86fc05:5000::/20fc05:5fff:ffff:ffff:ffff:ffff:ffff:ffff
87fc05:6000::/20fc05:6fff:ffff:ffff:ffff:ffff:ffff:ffff
88fc05:7000::/20fc05:7fff:ffff:ffff:ffff:ffff:ffff:ffff
89fc05:8000::/20fc05:8fff:ffff:ffff:ffff:ffff:ffff:ffff
90fc05:9000::/20fc05:9fff:ffff:ffff:ffff:ffff:ffff:ffff
91fc05:a000::/20fc05:afff:ffff:ffff:ffff:ffff:ffff:ffff
92fc05:b000::/20fc05:bfff:ffff:ffff:ffff:ffff:ffff:ffff
93fc05:c000::/20fc05:cfff:ffff:ffff:ffff:ffff:ffff:ffff
94fc05:d000::/20fc05:dfff:ffff:ffff:ffff:ffff:ffff:ffff
95fc05:e000::/20fc05:efff:ffff:ffff:ffff:ffff:ffff:ffff
96fc05:f000::/20fc05:ffff:ffff:ffff:ffff:ffff:ffff:ffff
97fc06::/20fc06:fff:ffff:ffff:ffff:ffff:ffff:ffff
98fc06:1000::/20fc06:1fff:ffff:ffff:ffff:ffff:ffff:ffff
99fc06:2000::/20fc06:2fff:ffff:ffff:ffff:ffff:ffff:ffff
100fc06:3000::/20fc06:3fff:ffff:ffff:ffff:ffff:ffff:ffff
101fc06:4000::/20fc06:4fff:ffff:ffff:ffff:ffff:ffff:ffff
102fc06:5000::/20fc06:5fff:ffff:ffff:ffff:ffff:ffff:ffff
103fc06:6000::/20fc06:6fff:ffff:ffff:ffff:ffff:ffff:ffff
104fc06:7000::/20fc06:7fff:ffff:ffff:ffff:ffff:ffff:ffff
105fc06:8000::/20fc06:8fff:ffff:ffff:ffff:ffff:ffff:ffff
106fc06:9000::/20fc06:9fff:ffff:ffff:ffff:ffff:ffff:ffff
107fc06:a000::/20fc06:afff:ffff:ffff:ffff:ffff:ffff:ffff
108fc06:b000::/20fc06:bfff:ffff:ffff:ffff:ffff:ffff:ffff
109fc06:c000::/20fc06:cfff:ffff:ffff:ffff:ffff:ffff:ffff
110fc06:d000::/20fc06:dfff:ffff:ffff:ffff:ffff:ffff:ffff
111fc06:e000::/20fc06:efff:ffff:ffff:ffff:ffff:ffff:ffff
112fc06:f000::/20fc06:ffff:ffff:ffff:ffff:ffff:ffff:ffff
113fc07::/20fc07:fff:ffff:ffff:ffff:ffff:ffff:ffff
114fc07:1000::/20fc07:1fff:ffff:ffff:ffff:ffff:ffff:ffff
115fc07:2000::/20fc07:2fff:ffff:ffff:ffff:ffff:ffff:ffff
116fc07:3000::/20fc07:3fff:ffff:ffff:ffff:ffff:ffff:ffff
117fc07:4000::/20fc07:4fff:ffff:ffff:ffff:ffff:ffff:ffff
118fc07:5000::/20fc07:5fff:ffff:ffff:ffff:ffff:ffff:ffff
119fc07:6000::/20fc07:6fff:ffff:ffff:ffff:ffff:ffff:ffff
120fc07:7000::/20fc07:7fff:ffff:ffff:ffff:ffff:ffff:ffff
121fc07:8000::/20fc07:8fff:ffff:ffff:ffff:ffff:ffff:ffff
122fc07:9000::/20fc07:9fff:ffff:ffff:ffff:ffff:ffff:ffff
123fc07:a000::/20fc07:afff:ffff:ffff:ffff:ffff:ffff:ffff
124fc07:b000::/20fc07:bfff:ffff:ffff:ffff:ffff:ffff:ffff
125fc07:c000::/20fc07:cfff:ffff:ffff:ffff:ffff:ffff:ffff
126fc07:d000::/20fc07:dfff:ffff:ffff:ffff:ffff:ffff:ffff
127fc07:e000::/20fc07:efff:ffff:ffff:ffff:ffff:ffff:ffff
128fc07:f000::/20fc07:ffff:ffff:ffff:ffff:ffff:ffff:ffff
129fc08::/20fc08:fff:ffff:ffff:ffff:ffff:ffff:ffff
130fc08:1000::/20fc08:1fff:ffff:ffff:ffff:ffff:ffff:ffff
131fc08:2000::/20fc08:2fff:ffff:ffff:ffff:ffff:ffff:ffff
132fc08:3000::/20fc08:3fff:ffff:ffff:ffff:ffff:ffff:ffff
133fc08:4000::/20fc08:4fff:ffff:ffff:ffff:ffff:ffff:ffff
134fc08:5000::/20fc08:5fff:ffff:ffff:ffff:ffff:ffff:ffff
135fc08:6000::/20fc08:6fff:ffff:ffff:ffff:ffff:ffff:ffff
136fc08:7000::/20fc08:7fff:ffff:ffff:ffff:ffff:ffff:ffff
137fc08:8000::/20fc08:8fff:ffff:ffff:ffff:ffff:ffff:ffff
138fc08:9000::/20fc08:9fff:ffff:ffff:ffff:ffff:ffff:ffff
139fc08:a000::/20fc08:afff:ffff:ffff:ffff:ffff:ffff:ffff
140fc08:b000::/20fc08:bfff:ffff:ffff:ffff:ffff:ffff:ffff
141fc08:c000::/20fc08:cfff:ffff:ffff:ffff:ffff:ffff:ffff
142fc08:d000::/20fc08:dfff:ffff:ffff:ffff:ffff:ffff:ffff
143fc08:e000::/20fc08:efff:ffff:ffff:ffff:ffff:ffff:ffff
144fc08:f000::/20fc08:ffff:ffff:ffff:ffff:ffff:ffff:ffff
145fc09::/20fc09:fff:ffff:ffff:ffff:ffff:ffff:ffff
146fc09:1000::/20fc09:1fff:ffff:ffff:ffff:ffff:ffff:ffff
147fc09:2000::/20fc09:2fff:ffff:ffff:ffff:ffff:ffff:ffff
148fc09:3000::/20fc09:3fff:ffff:ffff:ffff:ffff:ffff:ffff
149fc09:4000::/20fc09:4fff:ffff:ffff:ffff:ffff:ffff:ffff
150fc09:5000::/20fc09:5fff:ffff:ffff:ffff:ffff:ffff:ffff
151fc09:6000::/20fc09:6fff:ffff:ffff:ffff:ffff:ffff:ffff
152fc09:7000::/20fc09:7fff:ffff:ffff:ffff:ffff:ffff:ffff
153fc09:8000::/20fc09:8fff:ffff:ffff:ffff:ffff:ffff:ffff
154fc09:9000::/20fc09:9fff:ffff:ffff:ffff:ffff:ffff:ffff
155fc09:a000::/20fc09:afff:ffff:ffff:ffff:ffff:ffff:ffff
156fc09:b000::/20fc09:bfff:ffff:ffff:ffff:ffff:ffff:ffff
157fc09:c000::/20fc09:cfff:ffff:ffff:ffff:ffff:ffff:ffff
158fc09:d000::/20fc09:dfff:ffff:ffff:ffff:ffff:ffff:ffff
159fc09:e000::/20fc09:efff:ffff:ffff:ffff:ffff:ffff:ffff
160fc09:f000::/20fc09:ffff:ffff:ffff:ffff:ffff:ffff:ffff
161fc0a::/20fc0a:fff:ffff:ffff:ffff:ffff:ffff:ffff
162fc0a:1000::/20fc0a:1fff:ffff:ffff:ffff:ffff:ffff:ffff
163fc0a:2000::/20fc0a:2fff:ffff:ffff:ffff:ffff:ffff:ffff
164fc0a:3000::/20fc0a:3fff:ffff:ffff:ffff:ffff:ffff:ffff
165fc0a:4000::/20fc0a:4fff:ffff:ffff:ffff:ffff:ffff:ffff
166fc0a:5000::/20fc0a:5fff:ffff:ffff:ffff:ffff:ffff:ffff
167fc0a:6000::/20fc0a:6fff:ffff:ffff:ffff:ffff:ffff:ffff
168fc0a:7000::/20fc0a:7fff:ffff:ffff:ffff:ffff:ffff:ffff
169fc0a:8000::/20fc0a:8fff:ffff:ffff:ffff:ffff:ffff:ffff
170fc0a:9000::/20fc0a:9fff:ffff:ffff:ffff:ffff:ffff:ffff
171fc0a:a000::/20fc0a:afff:ffff:ffff:ffff:ffff:ffff:ffff
172fc0a:b000::/20fc0a:bfff:ffff:ffff:ffff:ffff:ffff:ffff
173fc0a:c000::/20fc0a:cfff:ffff:ffff:ffff:ffff:ffff:ffff
174fc0a:d000::/20fc0a:dfff:ffff:ffff:ffff:ffff:ffff:ffff
175fc0a:e000::/20fc0a:efff:ffff:ffff:ffff:ffff:ffff:ffff
176fc0a:f000::/20fc0a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
177fc0b::/20fc0b:fff:ffff:ffff:ffff:ffff:ffff:ffff
178fc0b:1000::/20fc0b:1fff:ffff:ffff:ffff:ffff:ffff:ffff
179fc0b:2000::/20fc0b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
180fc0b:3000::/20fc0b:3fff:ffff:ffff:ffff:ffff:ffff:ffff
181fc0b:4000::/20fc0b:4fff:ffff:ffff:ffff:ffff:ffff:ffff
182fc0b:5000::/20fc0b:5fff:ffff:ffff:ffff:ffff:ffff:ffff
183fc0b:6000::/20fc0b:6fff:ffff:ffff:ffff:ffff:ffff:ffff
184fc0b:7000::/20fc0b:7fff:ffff:ffff:ffff:ffff:ffff:ffff
185fc0b:8000::/20fc0b:8fff:ffff:ffff:ffff:ffff:ffff:ffff
186fc0b:9000::/20fc0b:9fff:ffff:ffff:ffff:ffff:ffff:ffff
187fc0b:a000::/20fc0b:afff:ffff:ffff:ffff:ffff:ffff:ffff
188fc0b:b000::/20fc0b:bfff:ffff:ffff:ffff:ffff:ffff:ffff
189fc0b:c000::/20fc0b:cfff:ffff:ffff:ffff:ffff:ffff:ffff
190fc0b:d000::/20fc0b:dfff:ffff:ffff:ffff:ffff:ffff:ffff
191fc0b:e000::/20fc0b:efff:ffff:ffff:ffff:ffff:ffff:ffff
192fc0b:f000::/20fc0b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
193fc0c::/20fc0c:fff:ffff:ffff:ffff:ffff:ffff:ffff
194fc0c:1000::/20fc0c:1fff:ffff:ffff:ffff:ffff:ffff:ffff
195fc0c:2000::/20fc0c:2fff:ffff:ffff:ffff:ffff:ffff:ffff
196fc0c:3000::/20fc0c:3fff:ffff:ffff:ffff:ffff:ffff:ffff
197fc0c:4000::/20fc0c:4fff:ffff:ffff:ffff:ffff:ffff:ffff
198fc0c:5000::/20fc0c:5fff:ffff:ffff:ffff:ffff:ffff:ffff
199fc0c:6000::/20fc0c:6fff:ffff:ffff:ffff:ffff:ffff:ffff
200fc0c:7000::/20fc0c:7fff:ffff:ffff:ffff:ffff:ffff:ffff
201fc0c:8000::/20fc0c:8fff:ffff:ffff:ffff:ffff:ffff:ffff
202fc0c:9000::/20fc0c:9fff:ffff:ffff:ffff:ffff:ffff:ffff
203fc0c:a000::/20fc0c:afff:ffff:ffff:ffff:ffff:ffff:ffff
204fc0c:b000::/20fc0c:bfff:ffff:ffff:ffff:ffff:ffff:ffff
205fc0c:c000::/20fc0c:cfff:ffff:ffff:ffff:ffff:ffff:ffff
206fc0c:d000::/20fc0c:dfff:ffff:ffff:ffff:ffff:ffff:ffff
207fc0c:e000::/20fc0c:efff:ffff:ffff:ffff:ffff:ffff:ffff
208fc0c:f000::/20fc0c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
209fc0d::/20fc0d:fff:ffff:ffff:ffff:ffff:ffff:ffff
210fc0d:1000::/20fc0d:1fff:ffff:ffff:ffff:ffff:ffff:ffff
211fc0d:2000::/20fc0d:2fff:ffff:ffff:ffff:ffff:ffff:ffff
212fc0d:3000::/20fc0d:3fff:ffff:ffff:ffff:ffff:ffff:ffff
213fc0d:4000::/20fc0d:4fff:ffff:ffff:ffff:ffff:ffff:ffff
214fc0d:5000::/20fc0d:5fff:ffff:ffff:ffff:ffff:ffff:ffff
215fc0d:6000::/20fc0d:6fff:ffff:ffff:ffff:ffff:ffff:ffff
216fc0d:7000::/20fc0d:7fff:ffff:ffff:ffff:ffff:ffff:ffff
217fc0d:8000::/20fc0d:8fff:ffff:ffff:ffff:ffff:ffff:ffff
218fc0d:9000::/20fc0d:9fff:ffff:ffff:ffff:ffff:ffff:ffff
219fc0d:a000::/20fc0d:afff:ffff:ffff:ffff:ffff:ffff:ffff
220fc0d:b000::/20fc0d:bfff:ffff:ffff:ffff:ffff:ffff:ffff
221fc0d:c000::/20fc0d:cfff:ffff:ffff:ffff:ffff:ffff:ffff
222fc0d:d000::/20fc0d:dfff:ffff:ffff:ffff:ffff:ffff:ffff
223fc0d:e000::/20fc0d:efff:ffff:ffff:ffff:ffff:ffff:ffff
224fc0d:f000::/20fc0d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
225fc0e::/20fc0e:fff:ffff:ffff:ffff:ffff:ffff:ffff
226fc0e:1000::/20fc0e:1fff:ffff:ffff:ffff:ffff:ffff:ffff
227fc0e:2000::/20fc0e:2fff:ffff:ffff:ffff:ffff:ffff:ffff
228fc0e:3000::/20fc0e:3fff:ffff:ffff:ffff:ffff:ffff:ffff
229fc0e:4000::/20fc0e:4fff:ffff:ffff:ffff:ffff:ffff:ffff
230fc0e:5000::/20fc0e:5fff:ffff:ffff:ffff:ffff:ffff:ffff
231fc0e:6000::/20fc0e:6fff:ffff:ffff:ffff:ffff:ffff:ffff
232fc0e:7000::/20fc0e:7fff:ffff:ffff:ffff:ffff:ffff:ffff
233fc0e:8000::/20fc0e:8fff:ffff:ffff:ffff:ffff:ffff:ffff
234fc0e:9000::/20fc0e:9fff:ffff:ffff:ffff:ffff:ffff:ffff
235fc0e:a000::/20fc0e:afff:ffff:ffff:ffff:ffff:ffff:ffff
236fc0e:b000::/20fc0e:bfff:ffff:ffff:ffff:ffff:ffff:ffff
237fc0e:c000::/20fc0e:cfff:ffff:ffff:ffff:ffff:ffff:ffff
238fc0e:d000::/20fc0e:dfff:ffff:ffff:ffff:ffff:ffff:ffff
239fc0e:e000::/20fc0e:efff:ffff:ffff:ffff:ffff:ffff:ffff
240fc0e:f000::/20fc0e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
241fc0f::/20fc0f:fff:ffff:ffff:ffff:ffff:ffff:ffff
242fc0f:1000::/20fc0f:1fff:ffff:ffff:ffff:ffff:ffff:ffff
243fc0f:2000::/20fc0f:2fff:ffff:ffff:ffff:ffff:ffff:ffff
244fc0f:3000::/20fc0f:3fff:ffff:ffff:ffff:ffff:ffff:ffff
245fc0f:4000::/20fc0f:4fff:ffff:ffff:ffff:ffff:ffff:ffff
246fc0f:5000::/20fc0f:5fff:ffff:ffff:ffff:ffff:ffff:ffff
247fc0f:6000::/20fc0f:6fff:ffff:ffff:ffff:ffff:ffff:ffff
248fc0f:7000::/20fc0f:7fff:ffff:ffff:ffff:ffff:ffff:ffff
249fc0f:8000::/20fc0f:8fff:ffff:ffff:ffff:ffff:ffff:ffff
250fc0f:9000::/20fc0f:9fff:ffff:ffff:ffff:ffff:ffff:ffff
251fc0f:a000::/20fc0f:afff:ffff:ffff:ffff:ffff:ffff:ffff
252fc0f:b000::/20fc0f:bfff:ffff:ffff:ffff:ffff:ffff:ffff
253fc0f:c000::/20fc0f:cfff:ffff:ffff:ffff:ffff:ffff:ffff
254fc0f:d000::/20fc0f:dfff:ffff:ffff:ffff:ffff:ffff:ffff
255fc0f:e000::/20fc0f:efff:ffff:ffff:ffff:ffff:ffff:ffff
256fc0f:f000::/20fc0f: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.