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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/16
Addresses2^112
/64 networks2^48
Network
fcff::/16
First address
fcff::
Last address
fcff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
fcff:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
f.f.c.f.ip6.arpa
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fcff::/16 makes 4,096 subnets of /28; the first 256 are listed.

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