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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/20
Addresses2^108
/64 networks2^44
Network
fc00::/20
First address
fc00::
Last address
fc00:fff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
324,518,553,658,426,726,783,156,020,576,256 (2^108)
/64 networks (LANs)
17,592,186,044,416 (2^44)
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 zone
0.0.0.c.f.ip6.arpa
Split into smaller subnets/32
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

fc00::/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1fc00::/32fc00:0:ffff:ffff:ffff:ffff:ffff:ffff
2fc00:1::/32fc00:1:ffff:ffff:ffff:ffff:ffff:ffff
3fc00:2::/32fc00:2:ffff:ffff:ffff:ffff:ffff:ffff
4fc00:3::/32fc00:3:ffff:ffff:ffff:ffff:ffff:ffff
5fc00:4::/32fc00:4:ffff:ffff:ffff:ffff:ffff:ffff
6fc00:5::/32fc00:5:ffff:ffff:ffff:ffff:ffff:ffff
7fc00:6::/32fc00:6:ffff:ffff:ffff:ffff:ffff:ffff
8fc00:7::/32fc00:7:ffff:ffff:ffff:ffff:ffff:ffff
9fc00:8::/32fc00:8:ffff:ffff:ffff:ffff:ffff:ffff
10fc00:9::/32fc00:9:ffff:ffff:ffff:ffff:ffff:ffff
11fc00:a::/32fc00:a:ffff:ffff:ffff:ffff:ffff:ffff
12fc00:b::/32fc00:b:ffff:ffff:ffff:ffff:ffff:ffff
13fc00:c::/32fc00:c:ffff:ffff:ffff:ffff:ffff:ffff
14fc00:d::/32fc00:d:ffff:ffff:ffff:ffff:ffff:ffff
15fc00:e::/32fc00:e:ffff:ffff:ffff:ffff:ffff:ffff
16fc00:f::/32fc00:f:ffff:ffff:ffff:ffff:ffff:ffff
17fc00:10::/32fc00:10:ffff:ffff:ffff:ffff:ffff:ffff
18fc00:11::/32fc00:11:ffff:ffff:ffff:ffff:ffff:ffff
19fc00:12::/32fc00:12:ffff:ffff:ffff:ffff:ffff:ffff
20fc00:13::/32fc00:13:ffff:ffff:ffff:ffff:ffff:ffff
21fc00:14::/32fc00:14:ffff:ffff:ffff:ffff:ffff:ffff
22fc00:15::/32fc00:15:ffff:ffff:ffff:ffff:ffff:ffff
23fc00:16::/32fc00:16:ffff:ffff:ffff:ffff:ffff:ffff
24fc00:17::/32fc00:17:ffff:ffff:ffff:ffff:ffff:ffff
25fc00:18::/32fc00:18:ffff:ffff:ffff:ffff:ffff:ffff
26fc00:19::/32fc00:19:ffff:ffff:ffff:ffff:ffff:ffff
27fc00:1a::/32fc00:1a:ffff:ffff:ffff:ffff:ffff:ffff
28fc00:1b::/32fc00:1b:ffff:ffff:ffff:ffff:ffff:ffff
29fc00:1c::/32fc00:1c:ffff:ffff:ffff:ffff:ffff:ffff
30fc00:1d::/32fc00:1d:ffff:ffff:ffff:ffff:ffff:ffff
31fc00:1e::/32fc00:1e:ffff:ffff:ffff:ffff:ffff:ffff
32fc00:1f::/32fc00:1f:ffff:ffff:ffff:ffff:ffff:ffff
33fc00:20::/32fc00:20:ffff:ffff:ffff:ffff:ffff:ffff
34fc00:21::/32fc00:21:ffff:ffff:ffff:ffff:ffff:ffff
35fc00:22::/32fc00:22:ffff:ffff:ffff:ffff:ffff:ffff
36fc00:23::/32fc00:23:ffff:ffff:ffff:ffff:ffff:ffff
37fc00:24::/32fc00:24:ffff:ffff:ffff:ffff:ffff:ffff
38fc00:25::/32fc00:25:ffff:ffff:ffff:ffff:ffff:ffff
39fc00:26::/32fc00:26:ffff:ffff:ffff:ffff:ffff:ffff
40fc00:27::/32fc00:27:ffff:ffff:ffff:ffff:ffff:ffff
41fc00:28::/32fc00:28:ffff:ffff:ffff:ffff:ffff:ffff
42fc00:29::/32fc00:29:ffff:ffff:ffff:ffff:ffff:ffff
43fc00:2a::/32fc00:2a:ffff:ffff:ffff:ffff:ffff:ffff
44fc00:2b::/32fc00:2b:ffff:ffff:ffff:ffff:ffff:ffff
45fc00:2c::/32fc00:2c:ffff:ffff:ffff:ffff:ffff:ffff
46fc00:2d::/32fc00:2d:ffff:ffff:ffff:ffff:ffff:ffff
47fc00:2e::/32fc00:2e:ffff:ffff:ffff:ffff:ffff:ffff
48fc00:2f::/32fc00:2f:ffff:ffff:ffff:ffff:ffff:ffff
49fc00:30::/32fc00:30:ffff:ffff:ffff:ffff:ffff:ffff
50fc00:31::/32fc00:31:ffff:ffff:ffff:ffff:ffff:ffff
51fc00:32::/32fc00:32:ffff:ffff:ffff:ffff:ffff:ffff
52fc00:33::/32fc00:33:ffff:ffff:ffff:ffff:ffff:ffff
53fc00:34::/32fc00:34:ffff:ffff:ffff:ffff:ffff:ffff
54fc00:35::/32fc00:35:ffff:ffff:ffff:ffff:ffff:ffff
55fc00:36::/32fc00:36:ffff:ffff:ffff:ffff:ffff:ffff
56fc00:37::/32fc00:37:ffff:ffff:ffff:ffff:ffff:ffff
57fc00:38::/32fc00:38:ffff:ffff:ffff:ffff:ffff:ffff
58fc00:39::/32fc00:39:ffff:ffff:ffff:ffff:ffff:ffff
59fc00:3a::/32fc00:3a:ffff:ffff:ffff:ffff:ffff:ffff
60fc00:3b::/32fc00:3b:ffff:ffff:ffff:ffff:ffff:ffff
61fc00:3c::/32fc00:3c:ffff:ffff:ffff:ffff:ffff:ffff
62fc00:3d::/32fc00:3d:ffff:ffff:ffff:ffff:ffff:ffff
63fc00:3e::/32fc00:3e:ffff:ffff:ffff:ffff:ffff:ffff
64fc00:3f::/32fc00:3f:ffff:ffff:ffff:ffff:ffff:ffff
65fc00:40::/32fc00:40:ffff:ffff:ffff:ffff:ffff:ffff
66fc00:41::/32fc00:41:ffff:ffff:ffff:ffff:ffff:ffff
67fc00:42::/32fc00:42:ffff:ffff:ffff:ffff:ffff:ffff
68fc00:43::/32fc00:43:ffff:ffff:ffff:ffff:ffff:ffff
69fc00:44::/32fc00:44:ffff:ffff:ffff:ffff:ffff:ffff
70fc00:45::/32fc00:45:ffff:ffff:ffff:ffff:ffff:ffff
71fc00:46::/32fc00:46:ffff:ffff:ffff:ffff:ffff:ffff
72fc00:47::/32fc00:47:ffff:ffff:ffff:ffff:ffff:ffff
73fc00:48::/32fc00:48:ffff:ffff:ffff:ffff:ffff:ffff
74fc00:49::/32fc00:49:ffff:ffff:ffff:ffff:ffff:ffff
75fc00:4a::/32fc00:4a:ffff:ffff:ffff:ffff:ffff:ffff
76fc00:4b::/32fc00:4b:ffff:ffff:ffff:ffff:ffff:ffff
77fc00:4c::/32fc00:4c:ffff:ffff:ffff:ffff:ffff:ffff
78fc00:4d::/32fc00:4d:ffff:ffff:ffff:ffff:ffff:ffff
79fc00:4e::/32fc00:4e:ffff:ffff:ffff:ffff:ffff:ffff
80fc00:4f::/32fc00:4f:ffff:ffff:ffff:ffff:ffff:ffff
81fc00:50::/32fc00:50:ffff:ffff:ffff:ffff:ffff:ffff
82fc00:51::/32fc00:51:ffff:ffff:ffff:ffff:ffff:ffff
83fc00:52::/32fc00:52:ffff:ffff:ffff:ffff:ffff:ffff
84fc00:53::/32fc00:53:ffff:ffff:ffff:ffff:ffff:ffff
85fc00:54::/32fc00:54:ffff:ffff:ffff:ffff:ffff:ffff
86fc00:55::/32fc00:55:ffff:ffff:ffff:ffff:ffff:ffff
87fc00:56::/32fc00:56:ffff:ffff:ffff:ffff:ffff:ffff
88fc00:57::/32fc00:57:ffff:ffff:ffff:ffff:ffff:ffff
89fc00:58::/32fc00:58:ffff:ffff:ffff:ffff:ffff:ffff
90fc00:59::/32fc00:59:ffff:ffff:ffff:ffff:ffff:ffff
91fc00:5a::/32fc00:5a:ffff:ffff:ffff:ffff:ffff:ffff
92fc00:5b::/32fc00:5b:ffff:ffff:ffff:ffff:ffff:ffff
93fc00:5c::/32fc00:5c:ffff:ffff:ffff:ffff:ffff:ffff
94fc00:5d::/32fc00:5d:ffff:ffff:ffff:ffff:ffff:ffff
95fc00:5e::/32fc00:5e:ffff:ffff:ffff:ffff:ffff:ffff
96fc00:5f::/32fc00:5f:ffff:ffff:ffff:ffff:ffff:ffff
97fc00:60::/32fc00:60:ffff:ffff:ffff:ffff:ffff:ffff
98fc00:61::/32fc00:61:ffff:ffff:ffff:ffff:ffff:ffff
99fc00:62::/32fc00:62:ffff:ffff:ffff:ffff:ffff:ffff
100fc00:63::/32fc00:63:ffff:ffff:ffff:ffff:ffff:ffff
101fc00:64::/32fc00:64:ffff:ffff:ffff:ffff:ffff:ffff
102fc00:65::/32fc00:65:ffff:ffff:ffff:ffff:ffff:ffff
103fc00:66::/32fc00:66:ffff:ffff:ffff:ffff:ffff:ffff
104fc00:67::/32fc00:67:ffff:ffff:ffff:ffff:ffff:ffff
105fc00:68::/32fc00:68:ffff:ffff:ffff:ffff:ffff:ffff
106fc00:69::/32fc00:69:ffff:ffff:ffff:ffff:ffff:ffff
107fc00:6a::/32fc00:6a:ffff:ffff:ffff:ffff:ffff:ffff
108fc00:6b::/32fc00:6b:ffff:ffff:ffff:ffff:ffff:ffff
109fc00:6c::/32fc00:6c:ffff:ffff:ffff:ffff:ffff:ffff
110fc00:6d::/32fc00:6d:ffff:ffff:ffff:ffff:ffff:ffff
111fc00:6e::/32fc00:6e:ffff:ffff:ffff:ffff:ffff:ffff
112fc00:6f::/32fc00:6f:ffff:ffff:ffff:ffff:ffff:ffff
113fc00:70::/32fc00:70:ffff:ffff:ffff:ffff:ffff:ffff
114fc00:71::/32fc00:71:ffff:ffff:ffff:ffff:ffff:ffff
115fc00:72::/32fc00:72:ffff:ffff:ffff:ffff:ffff:ffff
116fc00:73::/32fc00:73:ffff:ffff:ffff:ffff:ffff:ffff
117fc00:74::/32fc00:74:ffff:ffff:ffff:ffff:ffff:ffff
118fc00:75::/32fc00:75:ffff:ffff:ffff:ffff:ffff:ffff
119fc00:76::/32fc00:76:ffff:ffff:ffff:ffff:ffff:ffff
120fc00:77::/32fc00:77:ffff:ffff:ffff:ffff:ffff:ffff
121fc00:78::/32fc00:78:ffff:ffff:ffff:ffff:ffff:ffff
122fc00:79::/32fc00:79:ffff:ffff:ffff:ffff:ffff:ffff
123fc00:7a::/32fc00:7a:ffff:ffff:ffff:ffff:ffff:ffff
124fc00:7b::/32fc00:7b:ffff:ffff:ffff:ffff:ffff:ffff
125fc00:7c::/32fc00:7c:ffff:ffff:ffff:ffff:ffff:ffff
126fc00:7d::/32fc00:7d:ffff:ffff:ffff:ffff:ffff:ffff
127fc00:7e::/32fc00:7e:ffff:ffff:ffff:ffff:ffff:ffff
128fc00:7f::/32fc00:7f:ffff:ffff:ffff:ffff:ffff:ffff
129fc00:80::/32fc00:80:ffff:ffff:ffff:ffff:ffff:ffff
130fc00:81::/32fc00:81:ffff:ffff:ffff:ffff:ffff:ffff
131fc00:82::/32fc00:82:ffff:ffff:ffff:ffff:ffff:ffff
132fc00:83::/32fc00:83:ffff:ffff:ffff:ffff:ffff:ffff
133fc00:84::/32fc00:84:ffff:ffff:ffff:ffff:ffff:ffff
134fc00:85::/32fc00:85:ffff:ffff:ffff:ffff:ffff:ffff
135fc00:86::/32fc00:86:ffff:ffff:ffff:ffff:ffff:ffff
136fc00:87::/32fc00:87:ffff:ffff:ffff:ffff:ffff:ffff
137fc00:88::/32fc00:88:ffff:ffff:ffff:ffff:ffff:ffff
138fc00:89::/32fc00:89:ffff:ffff:ffff:ffff:ffff:ffff
139fc00:8a::/32fc00:8a:ffff:ffff:ffff:ffff:ffff:ffff
140fc00:8b::/32fc00:8b:ffff:ffff:ffff:ffff:ffff:ffff
141fc00:8c::/32fc00:8c:ffff:ffff:ffff:ffff:ffff:ffff
142fc00:8d::/32fc00:8d:ffff:ffff:ffff:ffff:ffff:ffff
143fc00:8e::/32fc00:8e:ffff:ffff:ffff:ffff:ffff:ffff
144fc00:8f::/32fc00:8f:ffff:ffff:ffff:ffff:ffff:ffff
145fc00:90::/32fc00:90:ffff:ffff:ffff:ffff:ffff:ffff
146fc00:91::/32fc00:91:ffff:ffff:ffff:ffff:ffff:ffff
147fc00:92::/32fc00:92:ffff:ffff:ffff:ffff:ffff:ffff
148fc00:93::/32fc00:93:ffff:ffff:ffff:ffff:ffff:ffff
149fc00:94::/32fc00:94:ffff:ffff:ffff:ffff:ffff:ffff
150fc00:95::/32fc00:95:ffff:ffff:ffff:ffff:ffff:ffff
151fc00:96::/32fc00:96:ffff:ffff:ffff:ffff:ffff:ffff
152fc00:97::/32fc00:97:ffff:ffff:ffff:ffff:ffff:ffff
153fc00:98::/32fc00:98:ffff:ffff:ffff:ffff:ffff:ffff
154fc00:99::/32fc00:99:ffff:ffff:ffff:ffff:ffff:ffff
155fc00:9a::/32fc00:9a:ffff:ffff:ffff:ffff:ffff:ffff
156fc00:9b::/32fc00:9b:ffff:ffff:ffff:ffff:ffff:ffff
157fc00:9c::/32fc00:9c:ffff:ffff:ffff:ffff:ffff:ffff
158fc00:9d::/32fc00:9d:ffff:ffff:ffff:ffff:ffff:ffff
159fc00:9e::/32fc00:9e:ffff:ffff:ffff:ffff:ffff:ffff
160fc00:9f::/32fc00:9f:ffff:ffff:ffff:ffff:ffff:ffff
161fc00:a0::/32fc00:a0:ffff:ffff:ffff:ffff:ffff:ffff
162fc00:a1::/32fc00:a1:ffff:ffff:ffff:ffff:ffff:ffff
163fc00:a2::/32fc00:a2:ffff:ffff:ffff:ffff:ffff:ffff
164fc00:a3::/32fc00:a3:ffff:ffff:ffff:ffff:ffff:ffff
165fc00:a4::/32fc00:a4:ffff:ffff:ffff:ffff:ffff:ffff
166fc00:a5::/32fc00:a5:ffff:ffff:ffff:ffff:ffff:ffff
167fc00:a6::/32fc00:a6:ffff:ffff:ffff:ffff:ffff:ffff
168fc00:a7::/32fc00:a7:ffff:ffff:ffff:ffff:ffff:ffff
169fc00:a8::/32fc00:a8:ffff:ffff:ffff:ffff:ffff:ffff
170fc00:a9::/32fc00:a9:ffff:ffff:ffff:ffff:ffff:ffff
171fc00:aa::/32fc00:aa:ffff:ffff:ffff:ffff:ffff:ffff
172fc00:ab::/32fc00:ab:ffff:ffff:ffff:ffff:ffff:ffff
173fc00:ac::/32fc00:ac:ffff:ffff:ffff:ffff:ffff:ffff
174fc00:ad::/32fc00:ad:ffff:ffff:ffff:ffff:ffff:ffff
175fc00:ae::/32fc00:ae:ffff:ffff:ffff:ffff:ffff:ffff
176fc00:af::/32fc00:af:ffff:ffff:ffff:ffff:ffff:ffff
177fc00:b0::/32fc00:b0:ffff:ffff:ffff:ffff:ffff:ffff
178fc00:b1::/32fc00:b1:ffff:ffff:ffff:ffff:ffff:ffff
179fc00:b2::/32fc00:b2:ffff:ffff:ffff:ffff:ffff:ffff
180fc00:b3::/32fc00:b3:ffff:ffff:ffff:ffff:ffff:ffff
181fc00:b4::/32fc00:b4:ffff:ffff:ffff:ffff:ffff:ffff
182fc00:b5::/32fc00:b5:ffff:ffff:ffff:ffff:ffff:ffff
183fc00:b6::/32fc00:b6:ffff:ffff:ffff:ffff:ffff:ffff
184fc00:b7::/32fc00:b7:ffff:ffff:ffff:ffff:ffff:ffff
185fc00:b8::/32fc00:b8:ffff:ffff:ffff:ffff:ffff:ffff
186fc00:b9::/32fc00:b9:ffff:ffff:ffff:ffff:ffff:ffff
187fc00:ba::/32fc00:ba:ffff:ffff:ffff:ffff:ffff:ffff
188fc00:bb::/32fc00:bb:ffff:ffff:ffff:ffff:ffff:ffff
189fc00:bc::/32fc00:bc:ffff:ffff:ffff:ffff:ffff:ffff
190fc00:bd::/32fc00:bd:ffff:ffff:ffff:ffff:ffff:ffff
191fc00:be::/32fc00:be:ffff:ffff:ffff:ffff:ffff:ffff
192fc00:bf::/32fc00:bf:ffff:ffff:ffff:ffff:ffff:ffff
193fc00:c0::/32fc00:c0:ffff:ffff:ffff:ffff:ffff:ffff
194fc00:c1::/32fc00:c1:ffff:ffff:ffff:ffff:ffff:ffff
195fc00:c2::/32fc00:c2:ffff:ffff:ffff:ffff:ffff:ffff
196fc00:c3::/32fc00:c3:ffff:ffff:ffff:ffff:ffff:ffff
197fc00:c4::/32fc00:c4:ffff:ffff:ffff:ffff:ffff:ffff
198fc00:c5::/32fc00:c5:ffff:ffff:ffff:ffff:ffff:ffff
199fc00:c6::/32fc00:c6:ffff:ffff:ffff:ffff:ffff:ffff
200fc00:c7::/32fc00:c7:ffff:ffff:ffff:ffff:ffff:ffff
201fc00:c8::/32fc00:c8:ffff:ffff:ffff:ffff:ffff:ffff
202fc00:c9::/32fc00:c9:ffff:ffff:ffff:ffff:ffff:ffff
203fc00:ca::/32fc00:ca:ffff:ffff:ffff:ffff:ffff:ffff
204fc00:cb::/32fc00:cb:ffff:ffff:ffff:ffff:ffff:ffff
205fc00:cc::/32fc00:cc:ffff:ffff:ffff:ffff:ffff:ffff
206fc00:cd::/32fc00:cd:ffff:ffff:ffff:ffff:ffff:ffff
207fc00:ce::/32fc00:ce:ffff:ffff:ffff:ffff:ffff:ffff
208fc00:cf::/32fc00:cf:ffff:ffff:ffff:ffff:ffff:ffff
209fc00:d0::/32fc00:d0:ffff:ffff:ffff:ffff:ffff:ffff
210fc00:d1::/32fc00:d1:ffff:ffff:ffff:ffff:ffff:ffff
211fc00:d2::/32fc00:d2:ffff:ffff:ffff:ffff:ffff:ffff
212fc00:d3::/32fc00:d3:ffff:ffff:ffff:ffff:ffff:ffff
213fc00:d4::/32fc00:d4:ffff:ffff:ffff:ffff:ffff:ffff
214fc00:d5::/32fc00:d5:ffff:ffff:ffff:ffff:ffff:ffff
215fc00:d6::/32fc00:d6:ffff:ffff:ffff:ffff:ffff:ffff
216fc00:d7::/32fc00:d7:ffff:ffff:ffff:ffff:ffff:ffff
217fc00:d8::/32fc00:d8:ffff:ffff:ffff:ffff:ffff:ffff
218fc00:d9::/32fc00:d9:ffff:ffff:ffff:ffff:ffff:ffff
219fc00:da::/32fc00:da:ffff:ffff:ffff:ffff:ffff:ffff
220fc00:db::/32fc00:db:ffff:ffff:ffff:ffff:ffff:ffff
221fc00:dc::/32fc00:dc:ffff:ffff:ffff:ffff:ffff:ffff
222fc00:dd::/32fc00:dd:ffff:ffff:ffff:ffff:ffff:ffff
223fc00:de::/32fc00:de:ffff:ffff:ffff:ffff:ffff:ffff
224fc00:df::/32fc00:df:ffff:ffff:ffff:ffff:ffff:ffff
225fc00:e0::/32fc00:e0:ffff:ffff:ffff:ffff:ffff:ffff
226fc00:e1::/32fc00:e1:ffff:ffff:ffff:ffff:ffff:ffff
227fc00:e2::/32fc00:e2:ffff:ffff:ffff:ffff:ffff:ffff
228fc00:e3::/32fc00:e3:ffff:ffff:ffff:ffff:ffff:ffff
229fc00:e4::/32fc00:e4:ffff:ffff:ffff:ffff:ffff:ffff
230fc00:e5::/32fc00:e5:ffff:ffff:ffff:ffff:ffff:ffff
231fc00:e6::/32fc00:e6:ffff:ffff:ffff:ffff:ffff:ffff
232fc00:e7::/32fc00:e7:ffff:ffff:ffff:ffff:ffff:ffff
233fc00:e8::/32fc00:e8:ffff:ffff:ffff:ffff:ffff:ffff
234fc00:e9::/32fc00:e9:ffff:ffff:ffff:ffff:ffff:ffff
235fc00:ea::/32fc00:ea:ffff:ffff:ffff:ffff:ffff:ffff
236fc00:eb::/32fc00:eb:ffff:ffff:ffff:ffff:ffff:ffff
237fc00:ec::/32fc00:ec:ffff:ffff:ffff:ffff:ffff:ffff
238fc00:ed::/32fc00:ed:ffff:ffff:ffff:ffff:ffff:ffff
239fc00:ee::/32fc00:ee:ffff:ffff:ffff:ffff:ffff:ffff
240fc00:ef::/32fc00:ef:ffff:ffff:ffff:ffff:ffff:ffff
241fc00:f0::/32fc00:f0:ffff:ffff:ffff:ffff:ffff:ffff
242fc00:f1::/32fc00:f1:ffff:ffff:ffff:ffff:ffff:ffff
243fc00:f2::/32fc00:f2:ffff:ffff:ffff:ffff:ffff:ffff
244fc00:f3::/32fc00:f3:ffff:ffff:ffff:ffff:ffff:ffff
245fc00:f4::/32fc00:f4:ffff:ffff:ffff:ffff:ffff:ffff
246fc00:f5::/32fc00:f5:ffff:ffff:ffff:ffff:ffff:ffff
247fc00:f6::/32fc00:f6:ffff:ffff:ffff:ffff:ffff:ffff
248fc00:f7::/32fc00:f7:ffff:ffff:ffff:ffff:ffff:ffff
249fc00:f8::/32fc00:f8:ffff:ffff:ffff:ffff:ffff:ffff
250fc00:f9::/32fc00:f9:ffff:ffff:ffff:ffff:ffff:ffff
251fc00:fa::/32fc00:fa:ffff:ffff:ffff:ffff:ffff:ffff
252fc00:fb::/32fc00:fb:ffff:ffff:ffff:ffff:ffff:ffff
253fc00:fc::/32fc00:fc:ffff:ffff:ffff:ffff:ffff:ffff
254fc00:fd::/32fc00:fd:ffff:ffff:ffff:ffff:ffff:ffff
255fc00:fe::/32fc00:fe:ffff:ffff:ffff:ffff:ffff:ffff
256fc00:ff::/32fc00: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.