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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
fc01:c000::/20
First address
fc01:c000::
Last address
fc01:cfff: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
fc01:c000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
c.1.0.c.f.ip6.arpa
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

fc01:c000::/20 makes 256 subnets of /28.

Subnets
#SubnetLast address
1fc01:c000::/28fc01:c00f:ffff:ffff:ffff:ffff:ffff:ffff
2fc01:c010::/28fc01:c01f:ffff:ffff:ffff:ffff:ffff:ffff
3fc01:c020::/28fc01:c02f:ffff:ffff:ffff:ffff:ffff:ffff
4fc01:c030::/28fc01:c03f:ffff:ffff:ffff:ffff:ffff:ffff
5fc01:c040::/28fc01:c04f:ffff:ffff:ffff:ffff:ffff:ffff
6fc01:c050::/28fc01:c05f:ffff:ffff:ffff:ffff:ffff:ffff
7fc01:c060::/28fc01:c06f:ffff:ffff:ffff:ffff:ffff:ffff
8fc01:c070::/28fc01:c07f:ffff:ffff:ffff:ffff:ffff:ffff
9fc01:c080::/28fc01:c08f:ffff:ffff:ffff:ffff:ffff:ffff
10fc01:c090::/28fc01:c09f:ffff:ffff:ffff:ffff:ffff:ffff
11fc01:c0a0::/28fc01:c0af:ffff:ffff:ffff:ffff:ffff:ffff
12fc01:c0b0::/28fc01:c0bf:ffff:ffff:ffff:ffff:ffff:ffff
13fc01:c0c0::/28fc01:c0cf:ffff:ffff:ffff:ffff:ffff:ffff
14fc01:c0d0::/28fc01:c0df:ffff:ffff:ffff:ffff:ffff:ffff
15fc01:c0e0::/28fc01:c0ef:ffff:ffff:ffff:ffff:ffff:ffff
16fc01:c0f0::/28fc01:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
17fc01:c100::/28fc01:c10f:ffff:ffff:ffff:ffff:ffff:ffff
18fc01:c110::/28fc01:c11f:ffff:ffff:ffff:ffff:ffff:ffff
19fc01:c120::/28fc01:c12f:ffff:ffff:ffff:ffff:ffff:ffff
20fc01:c130::/28fc01:c13f:ffff:ffff:ffff:ffff:ffff:ffff
21fc01:c140::/28fc01:c14f:ffff:ffff:ffff:ffff:ffff:ffff
22fc01:c150::/28fc01:c15f:ffff:ffff:ffff:ffff:ffff:ffff
23fc01:c160::/28fc01:c16f:ffff:ffff:ffff:ffff:ffff:ffff
24fc01:c170::/28fc01:c17f:ffff:ffff:ffff:ffff:ffff:ffff
25fc01:c180::/28fc01:c18f:ffff:ffff:ffff:ffff:ffff:ffff
26fc01:c190::/28fc01:c19f:ffff:ffff:ffff:ffff:ffff:ffff
27fc01:c1a0::/28fc01:c1af:ffff:ffff:ffff:ffff:ffff:ffff
28fc01:c1b0::/28fc01:c1bf:ffff:ffff:ffff:ffff:ffff:ffff
29fc01:c1c0::/28fc01:c1cf:ffff:ffff:ffff:ffff:ffff:ffff
30fc01:c1d0::/28fc01:c1df:ffff:ffff:ffff:ffff:ffff:ffff
31fc01:c1e0::/28fc01:c1ef:ffff:ffff:ffff:ffff:ffff:ffff
32fc01:c1f0::/28fc01:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
33fc01:c200::/28fc01:c20f:ffff:ffff:ffff:ffff:ffff:ffff
34fc01:c210::/28fc01:c21f:ffff:ffff:ffff:ffff:ffff:ffff
35fc01:c220::/28fc01:c22f:ffff:ffff:ffff:ffff:ffff:ffff
36fc01:c230::/28fc01:c23f:ffff:ffff:ffff:ffff:ffff:ffff
37fc01:c240::/28fc01:c24f:ffff:ffff:ffff:ffff:ffff:ffff
38fc01:c250::/28fc01:c25f:ffff:ffff:ffff:ffff:ffff:ffff
39fc01:c260::/28fc01:c26f:ffff:ffff:ffff:ffff:ffff:ffff
40fc01:c270::/28fc01:c27f:ffff:ffff:ffff:ffff:ffff:ffff
41fc01:c280::/28fc01:c28f:ffff:ffff:ffff:ffff:ffff:ffff
42fc01:c290::/28fc01:c29f:ffff:ffff:ffff:ffff:ffff:ffff
43fc01:c2a0::/28fc01:c2af:ffff:ffff:ffff:ffff:ffff:ffff
44fc01:c2b0::/28fc01:c2bf:ffff:ffff:ffff:ffff:ffff:ffff
45fc01:c2c0::/28fc01:c2cf:ffff:ffff:ffff:ffff:ffff:ffff
46fc01:c2d0::/28fc01:c2df:ffff:ffff:ffff:ffff:ffff:ffff
47fc01:c2e0::/28fc01:c2ef:ffff:ffff:ffff:ffff:ffff:ffff
48fc01:c2f0::/28fc01:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
49fc01:c300::/28fc01:c30f:ffff:ffff:ffff:ffff:ffff:ffff
50fc01:c310::/28fc01:c31f:ffff:ffff:ffff:ffff:ffff:ffff
51fc01:c320::/28fc01:c32f:ffff:ffff:ffff:ffff:ffff:ffff
52fc01:c330::/28fc01:c33f:ffff:ffff:ffff:ffff:ffff:ffff
53fc01:c340::/28fc01:c34f:ffff:ffff:ffff:ffff:ffff:ffff
54fc01:c350::/28fc01:c35f:ffff:ffff:ffff:ffff:ffff:ffff
55fc01:c360::/28fc01:c36f:ffff:ffff:ffff:ffff:ffff:ffff
56fc01:c370::/28fc01:c37f:ffff:ffff:ffff:ffff:ffff:ffff
57fc01:c380::/28fc01:c38f:ffff:ffff:ffff:ffff:ffff:ffff
58fc01:c390::/28fc01:c39f:ffff:ffff:ffff:ffff:ffff:ffff
59fc01:c3a0::/28fc01:c3af:ffff:ffff:ffff:ffff:ffff:ffff
60fc01:c3b0::/28fc01:c3bf:ffff:ffff:ffff:ffff:ffff:ffff
61fc01:c3c0::/28fc01:c3cf:ffff:ffff:ffff:ffff:ffff:ffff
62fc01:c3d0::/28fc01:c3df:ffff:ffff:ffff:ffff:ffff:ffff
63fc01:c3e0::/28fc01:c3ef:ffff:ffff:ffff:ffff:ffff:ffff
64fc01:c3f0::/28fc01:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
65fc01:c400::/28fc01:c40f:ffff:ffff:ffff:ffff:ffff:ffff
66fc01:c410::/28fc01:c41f:ffff:ffff:ffff:ffff:ffff:ffff
67fc01:c420::/28fc01:c42f:ffff:ffff:ffff:ffff:ffff:ffff
68fc01:c430::/28fc01:c43f:ffff:ffff:ffff:ffff:ffff:ffff
69fc01:c440::/28fc01:c44f:ffff:ffff:ffff:ffff:ffff:ffff
70fc01:c450::/28fc01:c45f:ffff:ffff:ffff:ffff:ffff:ffff
71fc01:c460::/28fc01:c46f:ffff:ffff:ffff:ffff:ffff:ffff
72fc01:c470::/28fc01:c47f:ffff:ffff:ffff:ffff:ffff:ffff
73fc01:c480::/28fc01:c48f:ffff:ffff:ffff:ffff:ffff:ffff
74fc01:c490::/28fc01:c49f:ffff:ffff:ffff:ffff:ffff:ffff
75fc01:c4a0::/28fc01:c4af:ffff:ffff:ffff:ffff:ffff:ffff
76fc01:c4b0::/28fc01:c4bf:ffff:ffff:ffff:ffff:ffff:ffff
77fc01:c4c0::/28fc01:c4cf:ffff:ffff:ffff:ffff:ffff:ffff
78fc01:c4d0::/28fc01:c4df:ffff:ffff:ffff:ffff:ffff:ffff
79fc01:c4e0::/28fc01:c4ef:ffff:ffff:ffff:ffff:ffff:ffff
80fc01:c4f0::/28fc01:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
81fc01:c500::/28fc01:c50f:ffff:ffff:ffff:ffff:ffff:ffff
82fc01:c510::/28fc01:c51f:ffff:ffff:ffff:ffff:ffff:ffff
83fc01:c520::/28fc01:c52f:ffff:ffff:ffff:ffff:ffff:ffff
84fc01:c530::/28fc01:c53f:ffff:ffff:ffff:ffff:ffff:ffff
85fc01:c540::/28fc01:c54f:ffff:ffff:ffff:ffff:ffff:ffff
86fc01:c550::/28fc01:c55f:ffff:ffff:ffff:ffff:ffff:ffff
87fc01:c560::/28fc01:c56f:ffff:ffff:ffff:ffff:ffff:ffff
88fc01:c570::/28fc01:c57f:ffff:ffff:ffff:ffff:ffff:ffff
89fc01:c580::/28fc01:c58f:ffff:ffff:ffff:ffff:ffff:ffff
90fc01:c590::/28fc01:c59f:ffff:ffff:ffff:ffff:ffff:ffff
91fc01:c5a0::/28fc01:c5af:ffff:ffff:ffff:ffff:ffff:ffff
92fc01:c5b0::/28fc01:c5bf:ffff:ffff:ffff:ffff:ffff:ffff
93fc01:c5c0::/28fc01:c5cf:ffff:ffff:ffff:ffff:ffff:ffff
94fc01:c5d0::/28fc01:c5df:ffff:ffff:ffff:ffff:ffff:ffff
95fc01:c5e0::/28fc01:c5ef:ffff:ffff:ffff:ffff:ffff:ffff
96fc01:c5f0::/28fc01:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
97fc01:c600::/28fc01:c60f:ffff:ffff:ffff:ffff:ffff:ffff
98fc01:c610::/28fc01:c61f:ffff:ffff:ffff:ffff:ffff:ffff
99fc01:c620::/28fc01:c62f:ffff:ffff:ffff:ffff:ffff:ffff
100fc01:c630::/28fc01:c63f:ffff:ffff:ffff:ffff:ffff:ffff
101fc01:c640::/28fc01:c64f:ffff:ffff:ffff:ffff:ffff:ffff
102fc01:c650::/28fc01:c65f:ffff:ffff:ffff:ffff:ffff:ffff
103fc01:c660::/28fc01:c66f:ffff:ffff:ffff:ffff:ffff:ffff
104fc01:c670::/28fc01:c67f:ffff:ffff:ffff:ffff:ffff:ffff
105fc01:c680::/28fc01:c68f:ffff:ffff:ffff:ffff:ffff:ffff
106fc01:c690::/28fc01:c69f:ffff:ffff:ffff:ffff:ffff:ffff
107fc01:c6a0::/28fc01:c6af:ffff:ffff:ffff:ffff:ffff:ffff
108fc01:c6b0::/28fc01:c6bf:ffff:ffff:ffff:ffff:ffff:ffff
109fc01:c6c0::/28fc01:c6cf:ffff:ffff:ffff:ffff:ffff:ffff
110fc01:c6d0::/28fc01:c6df:ffff:ffff:ffff:ffff:ffff:ffff
111fc01:c6e0::/28fc01:c6ef:ffff:ffff:ffff:ffff:ffff:ffff
112fc01:c6f0::/28fc01:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
113fc01:c700::/28fc01:c70f:ffff:ffff:ffff:ffff:ffff:ffff
114fc01:c710::/28fc01:c71f:ffff:ffff:ffff:ffff:ffff:ffff
115fc01:c720::/28fc01:c72f:ffff:ffff:ffff:ffff:ffff:ffff
116fc01:c730::/28fc01:c73f:ffff:ffff:ffff:ffff:ffff:ffff
117fc01:c740::/28fc01:c74f:ffff:ffff:ffff:ffff:ffff:ffff
118fc01:c750::/28fc01:c75f:ffff:ffff:ffff:ffff:ffff:ffff
119fc01:c760::/28fc01:c76f:ffff:ffff:ffff:ffff:ffff:ffff
120fc01:c770::/28fc01:c77f:ffff:ffff:ffff:ffff:ffff:ffff
121fc01:c780::/28fc01:c78f:ffff:ffff:ffff:ffff:ffff:ffff
122fc01:c790::/28fc01:c79f:ffff:ffff:ffff:ffff:ffff:ffff
123fc01:c7a0::/28fc01:c7af:ffff:ffff:ffff:ffff:ffff:ffff
124fc01:c7b0::/28fc01:c7bf:ffff:ffff:ffff:ffff:ffff:ffff
125fc01:c7c0::/28fc01:c7cf:ffff:ffff:ffff:ffff:ffff:ffff
126fc01:c7d0::/28fc01:c7df:ffff:ffff:ffff:ffff:ffff:ffff
127fc01:c7e0::/28fc01:c7ef:ffff:ffff:ffff:ffff:ffff:ffff
128fc01:c7f0::/28fc01:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
129fc01:c800::/28fc01:c80f:ffff:ffff:ffff:ffff:ffff:ffff
130fc01:c810::/28fc01:c81f:ffff:ffff:ffff:ffff:ffff:ffff
131fc01:c820::/28fc01:c82f:ffff:ffff:ffff:ffff:ffff:ffff
132fc01:c830::/28fc01:c83f:ffff:ffff:ffff:ffff:ffff:ffff
133fc01:c840::/28fc01:c84f:ffff:ffff:ffff:ffff:ffff:ffff
134fc01:c850::/28fc01:c85f:ffff:ffff:ffff:ffff:ffff:ffff
135fc01:c860::/28fc01:c86f:ffff:ffff:ffff:ffff:ffff:ffff
136fc01:c870::/28fc01:c87f:ffff:ffff:ffff:ffff:ffff:ffff
137fc01:c880::/28fc01:c88f:ffff:ffff:ffff:ffff:ffff:ffff
138fc01:c890::/28fc01:c89f:ffff:ffff:ffff:ffff:ffff:ffff
139fc01:c8a0::/28fc01:c8af:ffff:ffff:ffff:ffff:ffff:ffff
140fc01:c8b0::/28fc01:c8bf:ffff:ffff:ffff:ffff:ffff:ffff
141fc01:c8c0::/28fc01:c8cf:ffff:ffff:ffff:ffff:ffff:ffff
142fc01:c8d0::/28fc01:c8df:ffff:ffff:ffff:ffff:ffff:ffff
143fc01:c8e0::/28fc01:c8ef:ffff:ffff:ffff:ffff:ffff:ffff
144fc01:c8f0::/28fc01:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
145fc01:c900::/28fc01:c90f:ffff:ffff:ffff:ffff:ffff:ffff
146fc01:c910::/28fc01:c91f:ffff:ffff:ffff:ffff:ffff:ffff
147fc01:c920::/28fc01:c92f:ffff:ffff:ffff:ffff:ffff:ffff
148fc01:c930::/28fc01:c93f:ffff:ffff:ffff:ffff:ffff:ffff
149fc01:c940::/28fc01:c94f:ffff:ffff:ffff:ffff:ffff:ffff
150fc01:c950::/28fc01:c95f:ffff:ffff:ffff:ffff:ffff:ffff
151fc01:c960::/28fc01:c96f:ffff:ffff:ffff:ffff:ffff:ffff
152fc01:c970::/28fc01:c97f:ffff:ffff:ffff:ffff:ffff:ffff
153fc01:c980::/28fc01:c98f:ffff:ffff:ffff:ffff:ffff:ffff
154fc01:c990::/28fc01:c99f:ffff:ffff:ffff:ffff:ffff:ffff
155fc01:c9a0::/28fc01:c9af:ffff:ffff:ffff:ffff:ffff:ffff
156fc01:c9b0::/28fc01:c9bf:ffff:ffff:ffff:ffff:ffff:ffff
157fc01:c9c0::/28fc01:c9cf:ffff:ffff:ffff:ffff:ffff:ffff
158fc01:c9d0::/28fc01:c9df:ffff:ffff:ffff:ffff:ffff:ffff
159fc01:c9e0::/28fc01:c9ef:ffff:ffff:ffff:ffff:ffff:ffff
160fc01:c9f0::/28fc01:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
161fc01:ca00::/28fc01:ca0f:ffff:ffff:ffff:ffff:ffff:ffff
162fc01:ca10::/28fc01:ca1f:ffff:ffff:ffff:ffff:ffff:ffff
163fc01:ca20::/28fc01:ca2f:ffff:ffff:ffff:ffff:ffff:ffff
164fc01:ca30::/28fc01:ca3f:ffff:ffff:ffff:ffff:ffff:ffff
165fc01:ca40::/28fc01:ca4f:ffff:ffff:ffff:ffff:ffff:ffff
166fc01:ca50::/28fc01:ca5f:ffff:ffff:ffff:ffff:ffff:ffff
167fc01:ca60::/28fc01:ca6f:ffff:ffff:ffff:ffff:ffff:ffff
168fc01:ca70::/28fc01:ca7f:ffff:ffff:ffff:ffff:ffff:ffff
169fc01:ca80::/28fc01:ca8f:ffff:ffff:ffff:ffff:ffff:ffff
170fc01:ca90::/28fc01:ca9f:ffff:ffff:ffff:ffff:ffff:ffff
171fc01:caa0::/28fc01:caaf:ffff:ffff:ffff:ffff:ffff:ffff
172fc01:cab0::/28fc01:cabf:ffff:ffff:ffff:ffff:ffff:ffff
173fc01:cac0::/28fc01:cacf:ffff:ffff:ffff:ffff:ffff:ffff
174fc01:cad0::/28fc01:cadf:ffff:ffff:ffff:ffff:ffff:ffff
175fc01:cae0::/28fc01:caef:ffff:ffff:ffff:ffff:ffff:ffff
176fc01:caf0::/28fc01:caff:ffff:ffff:ffff:ffff:ffff:ffff
177fc01:cb00::/28fc01:cb0f:ffff:ffff:ffff:ffff:ffff:ffff
178fc01:cb10::/28fc01:cb1f:ffff:ffff:ffff:ffff:ffff:ffff
179fc01:cb20::/28fc01:cb2f:ffff:ffff:ffff:ffff:ffff:ffff
180fc01:cb30::/28fc01:cb3f:ffff:ffff:ffff:ffff:ffff:ffff
181fc01:cb40::/28fc01:cb4f:ffff:ffff:ffff:ffff:ffff:ffff
182fc01:cb50::/28fc01:cb5f:ffff:ffff:ffff:ffff:ffff:ffff
183fc01:cb60::/28fc01:cb6f:ffff:ffff:ffff:ffff:ffff:ffff
184fc01:cb70::/28fc01:cb7f:ffff:ffff:ffff:ffff:ffff:ffff
185fc01:cb80::/28fc01:cb8f:ffff:ffff:ffff:ffff:ffff:ffff
186fc01:cb90::/28fc01:cb9f:ffff:ffff:ffff:ffff:ffff:ffff
187fc01:cba0::/28fc01:cbaf:ffff:ffff:ffff:ffff:ffff:ffff
188fc01:cbb0::/28fc01:cbbf:ffff:ffff:ffff:ffff:ffff:ffff
189fc01:cbc0::/28fc01:cbcf:ffff:ffff:ffff:ffff:ffff:ffff
190fc01:cbd0::/28fc01:cbdf:ffff:ffff:ffff:ffff:ffff:ffff
191fc01:cbe0::/28fc01:cbef:ffff:ffff:ffff:ffff:ffff:ffff
192fc01:cbf0::/28fc01:cbff:ffff:ffff:ffff:ffff:ffff:ffff
193fc01:cc00::/28fc01:cc0f:ffff:ffff:ffff:ffff:ffff:ffff
194fc01:cc10::/28fc01:cc1f:ffff:ffff:ffff:ffff:ffff:ffff
195fc01:cc20::/28fc01:cc2f:ffff:ffff:ffff:ffff:ffff:ffff
196fc01:cc30::/28fc01:cc3f:ffff:ffff:ffff:ffff:ffff:ffff
197fc01:cc40::/28fc01:cc4f:ffff:ffff:ffff:ffff:ffff:ffff
198fc01:cc50::/28fc01:cc5f:ffff:ffff:ffff:ffff:ffff:ffff
199fc01:cc60::/28fc01:cc6f:ffff:ffff:ffff:ffff:ffff:ffff
200fc01:cc70::/28fc01:cc7f:ffff:ffff:ffff:ffff:ffff:ffff
201fc01:cc80::/28fc01:cc8f:ffff:ffff:ffff:ffff:ffff:ffff
202fc01:cc90::/28fc01:cc9f:ffff:ffff:ffff:ffff:ffff:ffff
203fc01:cca0::/28fc01:ccaf:ffff:ffff:ffff:ffff:ffff:ffff
204fc01:ccb0::/28fc01:ccbf:ffff:ffff:ffff:ffff:ffff:ffff
205fc01:ccc0::/28fc01:cccf:ffff:ffff:ffff:ffff:ffff:ffff
206fc01:ccd0::/28fc01:ccdf:ffff:ffff:ffff:ffff:ffff:ffff
207fc01:cce0::/28fc01:ccef:ffff:ffff:ffff:ffff:ffff:ffff
208fc01:ccf0::/28fc01:ccff:ffff:ffff:ffff:ffff:ffff:ffff
209fc01:cd00::/28fc01:cd0f:ffff:ffff:ffff:ffff:ffff:ffff
210fc01:cd10::/28fc01:cd1f:ffff:ffff:ffff:ffff:ffff:ffff
211fc01:cd20::/28fc01:cd2f:ffff:ffff:ffff:ffff:ffff:ffff
212fc01:cd30::/28fc01:cd3f:ffff:ffff:ffff:ffff:ffff:ffff
213fc01:cd40::/28fc01:cd4f:ffff:ffff:ffff:ffff:ffff:ffff
214fc01:cd50::/28fc01:cd5f:ffff:ffff:ffff:ffff:ffff:ffff
215fc01:cd60::/28fc01:cd6f:ffff:ffff:ffff:ffff:ffff:ffff
216fc01:cd70::/28fc01:cd7f:ffff:ffff:ffff:ffff:ffff:ffff
217fc01:cd80::/28fc01:cd8f:ffff:ffff:ffff:ffff:ffff:ffff
218fc01:cd90::/28fc01:cd9f:ffff:ffff:ffff:ffff:ffff:ffff
219fc01:cda0::/28fc01:cdaf:ffff:ffff:ffff:ffff:ffff:ffff
220fc01:cdb0::/28fc01:cdbf:ffff:ffff:ffff:ffff:ffff:ffff
221fc01:cdc0::/28fc01:cdcf:ffff:ffff:ffff:ffff:ffff:ffff
222fc01:cdd0::/28fc01:cddf:ffff:ffff:ffff:ffff:ffff:ffff
223fc01:cde0::/28fc01:cdef:ffff:ffff:ffff:ffff:ffff:ffff
224fc01:cdf0::/28fc01:cdff:ffff:ffff:ffff:ffff:ffff:ffff
225fc01:ce00::/28fc01:ce0f:ffff:ffff:ffff:ffff:ffff:ffff
226fc01:ce10::/28fc01:ce1f:ffff:ffff:ffff:ffff:ffff:ffff
227fc01:ce20::/28fc01:ce2f:ffff:ffff:ffff:ffff:ffff:ffff
228fc01:ce30::/28fc01:ce3f:ffff:ffff:ffff:ffff:ffff:ffff
229fc01:ce40::/28fc01:ce4f:ffff:ffff:ffff:ffff:ffff:ffff
230fc01:ce50::/28fc01:ce5f:ffff:ffff:ffff:ffff:ffff:ffff
231fc01:ce60::/28fc01:ce6f:ffff:ffff:ffff:ffff:ffff:ffff
232fc01:ce70::/28fc01:ce7f:ffff:ffff:ffff:ffff:ffff:ffff
233fc01:ce80::/28fc01:ce8f:ffff:ffff:ffff:ffff:ffff:ffff
234fc01:ce90::/28fc01:ce9f:ffff:ffff:ffff:ffff:ffff:ffff
235fc01:cea0::/28fc01:ceaf:ffff:ffff:ffff:ffff:ffff:ffff
236fc01:ceb0::/28fc01:cebf:ffff:ffff:ffff:ffff:ffff:ffff
237fc01:cec0::/28fc01:cecf:ffff:ffff:ffff:ffff:ffff:ffff
238fc01:ced0::/28fc01:cedf:ffff:ffff:ffff:ffff:ffff:ffff
239fc01:cee0::/28fc01:ceef:ffff:ffff:ffff:ffff:ffff:ffff
240fc01:cef0::/28fc01:ceff:ffff:ffff:ffff:ffff:ffff:ffff
241fc01:cf00::/28fc01:cf0f:ffff:ffff:ffff:ffff:ffff:ffff
242fc01:cf10::/28fc01:cf1f:ffff:ffff:ffff:ffff:ffff:ffff
243fc01:cf20::/28fc01:cf2f:ffff:ffff:ffff:ffff:ffff:ffff
244fc01:cf30::/28fc01:cf3f:ffff:ffff:ffff:ffff:ffff:ffff
245fc01:cf40::/28fc01:cf4f:ffff:ffff:ffff:ffff:ffff:ffff
246fc01:cf50::/28fc01:cf5f:ffff:ffff:ffff:ffff:ffff:ffff
247fc01:cf60::/28fc01:cf6f:ffff:ffff:ffff:ffff:ffff:ffff
248fc01:cf70::/28fc01:cf7f:ffff:ffff:ffff:ffff:ffff:ffff
249fc01:cf80::/28fc01:cf8f:ffff:ffff:ffff:ffff:ffff:ffff
250fc01:cf90::/28fc01:cf9f:ffff:ffff:ffff:ffff:ffff:ffff
251fc01:cfa0::/28fc01:cfaf:ffff:ffff:ffff:ffff:ffff:ffff
252fc01:cfb0::/28fc01:cfbf:ffff:ffff:ffff:ffff:ffff:ffff
253fc01:cfc0::/28fc01:cfcf:ffff:ffff:ffff:ffff:ffff:ffff
254fc01:cfd0::/28fc01:cfdf:ffff:ffff:ffff:ffff:ffff:ffff
255fc01:cfe0::/28fc01:cfef:ffff:ffff:ffff:ffff:ffff:ffff
256fc01:cff0::/28fc01:cfff: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.