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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/15
Addresses2^113
/64 networks2^49
Network
fc72::/15
First address
fc72::
Last address
fc73:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
10,384,593,717,069,655,257,060,992,658,440,192 (2^113)
/64 networks (LANs)
562,949,953,421,312 (2^49)
Full form
fc72:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zones
2.7.c.f.ip6.arpa
3.7.c.f.ip6.arpa
/15 is not on a 4-bit boundary, so it takes 2 /16 zones.
Split into smaller subnets/28
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/24 (512)/28 (8,192)

fc72::/15 makes 8,192 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
1fc72::/28fc72:f:ffff:ffff:ffff:ffff:ffff:ffff
2fc72:10::/28fc72:1f:ffff:ffff:ffff:ffff:ffff:ffff
3fc72:20::/28fc72:2f:ffff:ffff:ffff:ffff:ffff:ffff
4fc72:30::/28fc72:3f:ffff:ffff:ffff:ffff:ffff:ffff
5fc72:40::/28fc72:4f:ffff:ffff:ffff:ffff:ffff:ffff
6fc72:50::/28fc72:5f:ffff:ffff:ffff:ffff:ffff:ffff
7fc72:60::/28fc72:6f:ffff:ffff:ffff:ffff:ffff:ffff
8fc72:70::/28fc72:7f:ffff:ffff:ffff:ffff:ffff:ffff
9fc72:80::/28fc72:8f:ffff:ffff:ffff:ffff:ffff:ffff
10fc72:90::/28fc72:9f:ffff:ffff:ffff:ffff:ffff:ffff
11fc72:a0::/28fc72:af:ffff:ffff:ffff:ffff:ffff:ffff
12fc72:b0::/28fc72:bf:ffff:ffff:ffff:ffff:ffff:ffff
13fc72:c0::/28fc72:cf:ffff:ffff:ffff:ffff:ffff:ffff
14fc72:d0::/28fc72:df:ffff:ffff:ffff:ffff:ffff:ffff
15fc72:e0::/28fc72:ef:ffff:ffff:ffff:ffff:ffff:ffff
16fc72:f0::/28fc72:ff:ffff:ffff:ffff:ffff:ffff:ffff
17fc72:100::/28fc72:10f:ffff:ffff:ffff:ffff:ffff:ffff
18fc72:110::/28fc72:11f:ffff:ffff:ffff:ffff:ffff:ffff
19fc72:120::/28fc72:12f:ffff:ffff:ffff:ffff:ffff:ffff
20fc72:130::/28fc72:13f:ffff:ffff:ffff:ffff:ffff:ffff
21fc72:140::/28fc72:14f:ffff:ffff:ffff:ffff:ffff:ffff
22fc72:150::/28fc72:15f:ffff:ffff:ffff:ffff:ffff:ffff
23fc72:160::/28fc72:16f:ffff:ffff:ffff:ffff:ffff:ffff
24fc72:170::/28fc72:17f:ffff:ffff:ffff:ffff:ffff:ffff
25fc72:180::/28fc72:18f:ffff:ffff:ffff:ffff:ffff:ffff
26fc72:190::/28fc72:19f:ffff:ffff:ffff:ffff:ffff:ffff
27fc72:1a0::/28fc72:1af:ffff:ffff:ffff:ffff:ffff:ffff
28fc72:1b0::/28fc72:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29fc72:1c0::/28fc72:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30fc72:1d0::/28fc72:1df:ffff:ffff:ffff:ffff:ffff:ffff
31fc72:1e0::/28fc72:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32fc72:1f0::/28fc72:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33fc72:200::/28fc72:20f:ffff:ffff:ffff:ffff:ffff:ffff
34fc72:210::/28fc72:21f:ffff:ffff:ffff:ffff:ffff:ffff
35fc72:220::/28fc72:22f:ffff:ffff:ffff:ffff:ffff:ffff
36fc72:230::/28fc72:23f:ffff:ffff:ffff:ffff:ffff:ffff
37fc72:240::/28fc72:24f:ffff:ffff:ffff:ffff:ffff:ffff
38fc72:250::/28fc72:25f:ffff:ffff:ffff:ffff:ffff:ffff
39fc72:260::/28fc72:26f:ffff:ffff:ffff:ffff:ffff:ffff
40fc72:270::/28fc72:27f:ffff:ffff:ffff:ffff:ffff:ffff
41fc72:280::/28fc72:28f:ffff:ffff:ffff:ffff:ffff:ffff
42fc72:290::/28fc72:29f:ffff:ffff:ffff:ffff:ffff:ffff
43fc72:2a0::/28fc72:2af:ffff:ffff:ffff:ffff:ffff:ffff
44fc72:2b0::/28fc72:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45fc72:2c0::/28fc72:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46fc72:2d0::/28fc72:2df:ffff:ffff:ffff:ffff:ffff:ffff
47fc72:2e0::/28fc72:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48fc72:2f0::/28fc72:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49fc72:300::/28fc72:30f:ffff:ffff:ffff:ffff:ffff:ffff
50fc72:310::/28fc72:31f:ffff:ffff:ffff:ffff:ffff:ffff
51fc72:320::/28fc72:32f:ffff:ffff:ffff:ffff:ffff:ffff
52fc72:330::/28fc72:33f:ffff:ffff:ffff:ffff:ffff:ffff
53fc72:340::/28fc72:34f:ffff:ffff:ffff:ffff:ffff:ffff
54fc72:350::/28fc72:35f:ffff:ffff:ffff:ffff:ffff:ffff
55fc72:360::/28fc72:36f:ffff:ffff:ffff:ffff:ffff:ffff
56fc72:370::/28fc72:37f:ffff:ffff:ffff:ffff:ffff:ffff
57fc72:380::/28fc72:38f:ffff:ffff:ffff:ffff:ffff:ffff
58fc72:390::/28fc72:39f:ffff:ffff:ffff:ffff:ffff:ffff
59fc72:3a0::/28fc72:3af:ffff:ffff:ffff:ffff:ffff:ffff
60fc72:3b0::/28fc72:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61fc72:3c0::/28fc72:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62fc72:3d0::/28fc72:3df:ffff:ffff:ffff:ffff:ffff:ffff
63fc72:3e0::/28fc72:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64fc72:3f0::/28fc72:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65fc72:400::/28fc72:40f:ffff:ffff:ffff:ffff:ffff:ffff
66fc72:410::/28fc72:41f:ffff:ffff:ffff:ffff:ffff:ffff
67fc72:420::/28fc72:42f:ffff:ffff:ffff:ffff:ffff:ffff
68fc72:430::/28fc72:43f:ffff:ffff:ffff:ffff:ffff:ffff
69fc72:440::/28fc72:44f:ffff:ffff:ffff:ffff:ffff:ffff
70fc72:450::/28fc72:45f:ffff:ffff:ffff:ffff:ffff:ffff
71fc72:460::/28fc72:46f:ffff:ffff:ffff:ffff:ffff:ffff
72fc72:470::/28fc72:47f:ffff:ffff:ffff:ffff:ffff:ffff
73fc72:480::/28fc72:48f:ffff:ffff:ffff:ffff:ffff:ffff
74fc72:490::/28fc72:49f:ffff:ffff:ffff:ffff:ffff:ffff
75fc72:4a0::/28fc72:4af:ffff:ffff:ffff:ffff:ffff:ffff
76fc72:4b0::/28fc72:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77fc72:4c0::/28fc72:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78fc72:4d0::/28fc72:4df:ffff:ffff:ffff:ffff:ffff:ffff
79fc72:4e0::/28fc72:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80fc72:4f0::/28fc72:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81fc72:500::/28fc72:50f:ffff:ffff:ffff:ffff:ffff:ffff
82fc72:510::/28fc72:51f:ffff:ffff:ffff:ffff:ffff:ffff
83fc72:520::/28fc72:52f:ffff:ffff:ffff:ffff:ffff:ffff
84fc72:530::/28fc72:53f:ffff:ffff:ffff:ffff:ffff:ffff
85fc72:540::/28fc72:54f:ffff:ffff:ffff:ffff:ffff:ffff
86fc72:550::/28fc72:55f:ffff:ffff:ffff:ffff:ffff:ffff
87fc72:560::/28fc72:56f:ffff:ffff:ffff:ffff:ffff:ffff
88fc72:570::/28fc72:57f:ffff:ffff:ffff:ffff:ffff:ffff
89fc72:580::/28fc72:58f:ffff:ffff:ffff:ffff:ffff:ffff
90fc72:590::/28fc72:59f:ffff:ffff:ffff:ffff:ffff:ffff
91fc72:5a0::/28fc72:5af:ffff:ffff:ffff:ffff:ffff:ffff
92fc72:5b0::/28fc72:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93fc72:5c0::/28fc72:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94fc72:5d0::/28fc72:5df:ffff:ffff:ffff:ffff:ffff:ffff
95fc72:5e0::/28fc72:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96fc72:5f0::/28fc72:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97fc72:600::/28fc72:60f:ffff:ffff:ffff:ffff:ffff:ffff
98fc72:610::/28fc72:61f:ffff:ffff:ffff:ffff:ffff:ffff
99fc72:620::/28fc72:62f:ffff:ffff:ffff:ffff:ffff:ffff
100fc72:630::/28fc72:63f:ffff:ffff:ffff:ffff:ffff:ffff
101fc72:640::/28fc72:64f:ffff:ffff:ffff:ffff:ffff:ffff
102fc72:650::/28fc72:65f:ffff:ffff:ffff:ffff:ffff:ffff
103fc72:660::/28fc72:66f:ffff:ffff:ffff:ffff:ffff:ffff
104fc72:670::/28fc72:67f:ffff:ffff:ffff:ffff:ffff:ffff
105fc72:680::/28fc72:68f:ffff:ffff:ffff:ffff:ffff:ffff
106fc72:690::/28fc72:69f:ffff:ffff:ffff:ffff:ffff:ffff
107fc72:6a0::/28fc72:6af:ffff:ffff:ffff:ffff:ffff:ffff
108fc72:6b0::/28fc72:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109fc72:6c0::/28fc72:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110fc72:6d0::/28fc72:6df:ffff:ffff:ffff:ffff:ffff:ffff
111fc72:6e0::/28fc72:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112fc72:6f0::/28fc72:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113fc72:700::/28fc72:70f:ffff:ffff:ffff:ffff:ffff:ffff
114fc72:710::/28fc72:71f:ffff:ffff:ffff:ffff:ffff:ffff
115fc72:720::/28fc72:72f:ffff:ffff:ffff:ffff:ffff:ffff
116fc72:730::/28fc72:73f:ffff:ffff:ffff:ffff:ffff:ffff
117fc72:740::/28fc72:74f:ffff:ffff:ffff:ffff:ffff:ffff
118fc72:750::/28fc72:75f:ffff:ffff:ffff:ffff:ffff:ffff
119fc72:760::/28fc72:76f:ffff:ffff:ffff:ffff:ffff:ffff
120fc72:770::/28fc72:77f:ffff:ffff:ffff:ffff:ffff:ffff
121fc72:780::/28fc72:78f:ffff:ffff:ffff:ffff:ffff:ffff
122fc72:790::/28fc72:79f:ffff:ffff:ffff:ffff:ffff:ffff
123fc72:7a0::/28fc72:7af:ffff:ffff:ffff:ffff:ffff:ffff
124fc72:7b0::/28fc72:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125fc72:7c0::/28fc72:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126fc72:7d0::/28fc72:7df:ffff:ffff:ffff:ffff:ffff:ffff
127fc72:7e0::/28fc72:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128fc72:7f0::/28fc72:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129fc72:800::/28fc72:80f:ffff:ffff:ffff:ffff:ffff:ffff
130fc72:810::/28fc72:81f:ffff:ffff:ffff:ffff:ffff:ffff
131fc72:820::/28fc72:82f:ffff:ffff:ffff:ffff:ffff:ffff
132fc72:830::/28fc72:83f:ffff:ffff:ffff:ffff:ffff:ffff
133fc72:840::/28fc72:84f:ffff:ffff:ffff:ffff:ffff:ffff
134fc72:850::/28fc72:85f:ffff:ffff:ffff:ffff:ffff:ffff
135fc72:860::/28fc72:86f:ffff:ffff:ffff:ffff:ffff:ffff
136fc72:870::/28fc72:87f:ffff:ffff:ffff:ffff:ffff:ffff
137fc72:880::/28fc72:88f:ffff:ffff:ffff:ffff:ffff:ffff
138fc72:890::/28fc72:89f:ffff:ffff:ffff:ffff:ffff:ffff
139fc72:8a0::/28fc72:8af:ffff:ffff:ffff:ffff:ffff:ffff
140fc72:8b0::/28fc72:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141fc72:8c0::/28fc72:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142fc72:8d0::/28fc72:8df:ffff:ffff:ffff:ffff:ffff:ffff
143fc72:8e0::/28fc72:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144fc72:8f0::/28fc72:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145fc72:900::/28fc72:90f:ffff:ffff:ffff:ffff:ffff:ffff
146fc72:910::/28fc72:91f:ffff:ffff:ffff:ffff:ffff:ffff
147fc72:920::/28fc72:92f:ffff:ffff:ffff:ffff:ffff:ffff
148fc72:930::/28fc72:93f:ffff:ffff:ffff:ffff:ffff:ffff
149fc72:940::/28fc72:94f:ffff:ffff:ffff:ffff:ffff:ffff
150fc72:950::/28fc72:95f:ffff:ffff:ffff:ffff:ffff:ffff
151fc72:960::/28fc72:96f:ffff:ffff:ffff:ffff:ffff:ffff
152fc72:970::/28fc72:97f:ffff:ffff:ffff:ffff:ffff:ffff
153fc72:980::/28fc72:98f:ffff:ffff:ffff:ffff:ffff:ffff
154fc72:990::/28fc72:99f:ffff:ffff:ffff:ffff:ffff:ffff
155fc72:9a0::/28fc72:9af:ffff:ffff:ffff:ffff:ffff:ffff
156fc72:9b0::/28fc72:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157fc72:9c0::/28fc72:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158fc72:9d0::/28fc72:9df:ffff:ffff:ffff:ffff:ffff:ffff
159fc72:9e0::/28fc72:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160fc72:9f0::/28fc72:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161fc72:a00::/28fc72:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162fc72:a10::/28fc72:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163fc72:a20::/28fc72:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164fc72:a30::/28fc72:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165fc72:a40::/28fc72:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166fc72:a50::/28fc72:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167fc72:a60::/28fc72:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168fc72:a70::/28fc72:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169fc72:a80::/28fc72:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170fc72:a90::/28fc72:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171fc72:aa0::/28fc72:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172fc72:ab0::/28fc72:abf:ffff:ffff:ffff:ffff:ffff:ffff
173fc72:ac0::/28fc72:acf:ffff:ffff:ffff:ffff:ffff:ffff
174fc72:ad0::/28fc72:adf:ffff:ffff:ffff:ffff:ffff:ffff
175fc72:ae0::/28fc72:aef:ffff:ffff:ffff:ffff:ffff:ffff
176fc72:af0::/28fc72:aff:ffff:ffff:ffff:ffff:ffff:ffff
177fc72:b00::/28fc72:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178fc72:b10::/28fc72:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179fc72:b20::/28fc72:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180fc72:b30::/28fc72:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181fc72:b40::/28fc72:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182fc72:b50::/28fc72:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183fc72:b60::/28fc72:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184fc72:b70::/28fc72:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185fc72:b80::/28fc72:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186fc72:b90::/28fc72:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187fc72:ba0::/28fc72:baf:ffff:ffff:ffff:ffff:ffff:ffff
188fc72:bb0::/28fc72:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189fc72:bc0::/28fc72:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190fc72:bd0::/28fc72:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191fc72:be0::/28fc72:bef:ffff:ffff:ffff:ffff:ffff:ffff
192fc72:bf0::/28fc72:bff:ffff:ffff:ffff:ffff:ffff:ffff
193fc72:c00::/28fc72:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194fc72:c10::/28fc72:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195fc72:c20::/28fc72:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196fc72:c30::/28fc72:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197fc72:c40::/28fc72:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198fc72:c50::/28fc72:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199fc72:c60::/28fc72:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200fc72:c70::/28fc72:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201fc72:c80::/28fc72:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202fc72:c90::/28fc72:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203fc72:ca0::/28fc72:caf:ffff:ffff:ffff:ffff:ffff:ffff
204fc72:cb0::/28fc72:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205fc72:cc0::/28fc72:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206fc72:cd0::/28fc72:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207fc72:ce0::/28fc72:cef:ffff:ffff:ffff:ffff:ffff:ffff
208fc72:cf0::/28fc72:cff:ffff:ffff:ffff:ffff:ffff:ffff
209fc72:d00::/28fc72:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210fc72:d10::/28fc72:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211fc72:d20::/28fc72:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212fc72:d30::/28fc72:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213fc72:d40::/28fc72:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214fc72:d50::/28fc72:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215fc72:d60::/28fc72:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216fc72:d70::/28fc72:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217fc72:d80::/28fc72:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218fc72:d90::/28fc72:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219fc72:da0::/28fc72:daf:ffff:ffff:ffff:ffff:ffff:ffff
220fc72:db0::/28fc72:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221fc72:dc0::/28fc72:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222fc72:dd0::/28fc72:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223fc72:de0::/28fc72:def:ffff:ffff:ffff:ffff:ffff:ffff
224fc72:df0::/28fc72:dff:ffff:ffff:ffff:ffff:ffff:ffff
225fc72:e00::/28fc72:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226fc72:e10::/28fc72:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227fc72:e20::/28fc72:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228fc72:e30::/28fc72:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229fc72:e40::/28fc72:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230fc72:e50::/28fc72:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231fc72:e60::/28fc72:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232fc72:e70::/28fc72:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233fc72:e80::/28fc72:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234fc72:e90::/28fc72:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235fc72:ea0::/28fc72:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236fc72:eb0::/28fc72:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237fc72:ec0::/28fc72:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238fc72:ed0::/28fc72:edf:ffff:ffff:ffff:ffff:ffff:ffff
239fc72:ee0::/28fc72:eef:ffff:ffff:ffff:ffff:ffff:ffff
240fc72:ef0::/28fc72:eff:ffff:ffff:ffff:ffff:ffff:ffff
241fc72:f00::/28fc72:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242fc72:f10::/28fc72:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243fc72:f20::/28fc72:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244fc72:f30::/28fc72:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245fc72:f40::/28fc72:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246fc72:f50::/28fc72:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247fc72:f60::/28fc72:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248fc72:f70::/28fc72:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249fc72:f80::/28fc72:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250fc72:f90::/28fc72:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251fc72:fa0::/28fc72:faf:ffff:ffff:ffff:ffff:ffff:ffff
252fc72:fb0::/28fc72:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253fc72:fc0::/28fc72:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254fc72:fd0::/28fc72:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255fc72:fe0::/28fc72:fef:ffff:ffff:ffff:ffff:ffff:ffff
256fc72:ff0::/28fc72:fff: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.