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Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

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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
ffb1::/16
First address
ffb1::
Last address
ffb1: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
ffb1:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
1.b.f.f.ip6.arpa
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ffb1::/16 makes 4,096 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
1ffb1::/28ffb1:f:ffff:ffff:ffff:ffff:ffff:ffff
2ffb1:10::/28ffb1:1f:ffff:ffff:ffff:ffff:ffff:ffff
3ffb1:20::/28ffb1:2f:ffff:ffff:ffff:ffff:ffff:ffff
4ffb1:30::/28ffb1:3f:ffff:ffff:ffff:ffff:ffff:ffff
5ffb1:40::/28ffb1:4f:ffff:ffff:ffff:ffff:ffff:ffff
6ffb1:50::/28ffb1:5f:ffff:ffff:ffff:ffff:ffff:ffff
7ffb1:60::/28ffb1:6f:ffff:ffff:ffff:ffff:ffff:ffff
8ffb1:70::/28ffb1:7f:ffff:ffff:ffff:ffff:ffff:ffff
9ffb1:80::/28ffb1:8f:ffff:ffff:ffff:ffff:ffff:ffff
10ffb1:90::/28ffb1:9f:ffff:ffff:ffff:ffff:ffff:ffff
11ffb1:a0::/28ffb1:af:ffff:ffff:ffff:ffff:ffff:ffff
12ffb1:b0::/28ffb1:bf:ffff:ffff:ffff:ffff:ffff:ffff
13ffb1:c0::/28ffb1:cf:ffff:ffff:ffff:ffff:ffff:ffff
14ffb1:d0::/28ffb1:df:ffff:ffff:ffff:ffff:ffff:ffff
15ffb1:e0::/28ffb1:ef:ffff:ffff:ffff:ffff:ffff:ffff
16ffb1:f0::/28ffb1:ff:ffff:ffff:ffff:ffff:ffff:ffff
17ffb1:100::/28ffb1:10f:ffff:ffff:ffff:ffff:ffff:ffff
18ffb1:110::/28ffb1:11f:ffff:ffff:ffff:ffff:ffff:ffff
19ffb1:120::/28ffb1:12f:ffff:ffff:ffff:ffff:ffff:ffff
20ffb1:130::/28ffb1:13f:ffff:ffff:ffff:ffff:ffff:ffff
21ffb1:140::/28ffb1:14f:ffff:ffff:ffff:ffff:ffff:ffff
22ffb1:150::/28ffb1:15f:ffff:ffff:ffff:ffff:ffff:ffff
23ffb1:160::/28ffb1:16f:ffff:ffff:ffff:ffff:ffff:ffff
24ffb1:170::/28ffb1:17f:ffff:ffff:ffff:ffff:ffff:ffff
25ffb1:180::/28ffb1:18f:ffff:ffff:ffff:ffff:ffff:ffff
26ffb1:190::/28ffb1:19f:ffff:ffff:ffff:ffff:ffff:ffff
27ffb1:1a0::/28ffb1:1af:ffff:ffff:ffff:ffff:ffff:ffff
28ffb1:1b0::/28ffb1:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29ffb1:1c0::/28ffb1:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30ffb1:1d0::/28ffb1:1df:ffff:ffff:ffff:ffff:ffff:ffff
31ffb1:1e0::/28ffb1:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32ffb1:1f0::/28ffb1:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33ffb1:200::/28ffb1:20f:ffff:ffff:ffff:ffff:ffff:ffff
34ffb1:210::/28ffb1:21f:ffff:ffff:ffff:ffff:ffff:ffff
35ffb1:220::/28ffb1:22f:ffff:ffff:ffff:ffff:ffff:ffff
36ffb1:230::/28ffb1:23f:ffff:ffff:ffff:ffff:ffff:ffff
37ffb1:240::/28ffb1:24f:ffff:ffff:ffff:ffff:ffff:ffff
38ffb1:250::/28ffb1:25f:ffff:ffff:ffff:ffff:ffff:ffff
39ffb1:260::/28ffb1:26f:ffff:ffff:ffff:ffff:ffff:ffff
40ffb1:270::/28ffb1:27f:ffff:ffff:ffff:ffff:ffff:ffff
41ffb1:280::/28ffb1:28f:ffff:ffff:ffff:ffff:ffff:ffff
42ffb1:290::/28ffb1:29f:ffff:ffff:ffff:ffff:ffff:ffff
43ffb1:2a0::/28ffb1:2af:ffff:ffff:ffff:ffff:ffff:ffff
44ffb1:2b0::/28ffb1:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45ffb1:2c0::/28ffb1:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46ffb1:2d0::/28ffb1:2df:ffff:ffff:ffff:ffff:ffff:ffff
47ffb1:2e0::/28ffb1:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48ffb1:2f0::/28ffb1:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49ffb1:300::/28ffb1:30f:ffff:ffff:ffff:ffff:ffff:ffff
50ffb1:310::/28ffb1:31f:ffff:ffff:ffff:ffff:ffff:ffff
51ffb1:320::/28ffb1:32f:ffff:ffff:ffff:ffff:ffff:ffff
52ffb1:330::/28ffb1:33f:ffff:ffff:ffff:ffff:ffff:ffff
53ffb1:340::/28ffb1:34f:ffff:ffff:ffff:ffff:ffff:ffff
54ffb1:350::/28ffb1:35f:ffff:ffff:ffff:ffff:ffff:ffff
55ffb1:360::/28ffb1:36f:ffff:ffff:ffff:ffff:ffff:ffff
56ffb1:370::/28ffb1:37f:ffff:ffff:ffff:ffff:ffff:ffff
57ffb1:380::/28ffb1:38f:ffff:ffff:ffff:ffff:ffff:ffff
58ffb1:390::/28ffb1:39f:ffff:ffff:ffff:ffff:ffff:ffff
59ffb1:3a0::/28ffb1:3af:ffff:ffff:ffff:ffff:ffff:ffff
60ffb1:3b0::/28ffb1:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61ffb1:3c0::/28ffb1:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62ffb1:3d0::/28ffb1:3df:ffff:ffff:ffff:ffff:ffff:ffff
63ffb1:3e0::/28ffb1:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64ffb1:3f0::/28ffb1:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65ffb1:400::/28ffb1:40f:ffff:ffff:ffff:ffff:ffff:ffff
66ffb1:410::/28ffb1:41f:ffff:ffff:ffff:ffff:ffff:ffff
67ffb1:420::/28ffb1:42f:ffff:ffff:ffff:ffff:ffff:ffff
68ffb1:430::/28ffb1:43f:ffff:ffff:ffff:ffff:ffff:ffff
69ffb1:440::/28ffb1:44f:ffff:ffff:ffff:ffff:ffff:ffff
70ffb1:450::/28ffb1:45f:ffff:ffff:ffff:ffff:ffff:ffff
71ffb1:460::/28ffb1:46f:ffff:ffff:ffff:ffff:ffff:ffff
72ffb1:470::/28ffb1:47f:ffff:ffff:ffff:ffff:ffff:ffff
73ffb1:480::/28ffb1:48f:ffff:ffff:ffff:ffff:ffff:ffff
74ffb1:490::/28ffb1:49f:ffff:ffff:ffff:ffff:ffff:ffff
75ffb1:4a0::/28ffb1:4af:ffff:ffff:ffff:ffff:ffff:ffff
76ffb1:4b0::/28ffb1:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77ffb1:4c0::/28ffb1:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78ffb1:4d0::/28ffb1:4df:ffff:ffff:ffff:ffff:ffff:ffff
79ffb1:4e0::/28ffb1:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80ffb1:4f0::/28ffb1:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81ffb1:500::/28ffb1:50f:ffff:ffff:ffff:ffff:ffff:ffff
82ffb1:510::/28ffb1:51f:ffff:ffff:ffff:ffff:ffff:ffff
83ffb1:520::/28ffb1:52f:ffff:ffff:ffff:ffff:ffff:ffff
84ffb1:530::/28ffb1:53f:ffff:ffff:ffff:ffff:ffff:ffff
85ffb1:540::/28ffb1:54f:ffff:ffff:ffff:ffff:ffff:ffff
86ffb1:550::/28ffb1:55f:ffff:ffff:ffff:ffff:ffff:ffff
87ffb1:560::/28ffb1:56f:ffff:ffff:ffff:ffff:ffff:ffff
88ffb1:570::/28ffb1:57f:ffff:ffff:ffff:ffff:ffff:ffff
89ffb1:580::/28ffb1:58f:ffff:ffff:ffff:ffff:ffff:ffff
90ffb1:590::/28ffb1:59f:ffff:ffff:ffff:ffff:ffff:ffff
91ffb1:5a0::/28ffb1:5af:ffff:ffff:ffff:ffff:ffff:ffff
92ffb1:5b0::/28ffb1:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93ffb1:5c0::/28ffb1:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94ffb1:5d0::/28ffb1:5df:ffff:ffff:ffff:ffff:ffff:ffff
95ffb1:5e0::/28ffb1:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96ffb1:5f0::/28ffb1:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97ffb1:600::/28ffb1:60f:ffff:ffff:ffff:ffff:ffff:ffff
98ffb1:610::/28ffb1:61f:ffff:ffff:ffff:ffff:ffff:ffff
99ffb1:620::/28ffb1:62f:ffff:ffff:ffff:ffff:ffff:ffff
100ffb1:630::/28ffb1:63f:ffff:ffff:ffff:ffff:ffff:ffff
101ffb1:640::/28ffb1:64f:ffff:ffff:ffff:ffff:ffff:ffff
102ffb1:650::/28ffb1:65f:ffff:ffff:ffff:ffff:ffff:ffff
103ffb1:660::/28ffb1:66f:ffff:ffff:ffff:ffff:ffff:ffff
104ffb1:670::/28ffb1:67f:ffff:ffff:ffff:ffff:ffff:ffff
105ffb1:680::/28ffb1:68f:ffff:ffff:ffff:ffff:ffff:ffff
106ffb1:690::/28ffb1:69f:ffff:ffff:ffff:ffff:ffff:ffff
107ffb1:6a0::/28ffb1:6af:ffff:ffff:ffff:ffff:ffff:ffff
108ffb1:6b0::/28ffb1:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109ffb1:6c0::/28ffb1:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110ffb1:6d0::/28ffb1:6df:ffff:ffff:ffff:ffff:ffff:ffff
111ffb1:6e0::/28ffb1:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112ffb1:6f0::/28ffb1:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113ffb1:700::/28ffb1:70f:ffff:ffff:ffff:ffff:ffff:ffff
114ffb1:710::/28ffb1:71f:ffff:ffff:ffff:ffff:ffff:ffff
115ffb1:720::/28ffb1:72f:ffff:ffff:ffff:ffff:ffff:ffff
116ffb1:730::/28ffb1:73f:ffff:ffff:ffff:ffff:ffff:ffff
117ffb1:740::/28ffb1:74f:ffff:ffff:ffff:ffff:ffff:ffff
118ffb1:750::/28ffb1:75f:ffff:ffff:ffff:ffff:ffff:ffff
119ffb1:760::/28ffb1:76f:ffff:ffff:ffff:ffff:ffff:ffff
120ffb1:770::/28ffb1:77f:ffff:ffff:ffff:ffff:ffff:ffff
121ffb1:780::/28ffb1:78f:ffff:ffff:ffff:ffff:ffff:ffff
122ffb1:790::/28ffb1:79f:ffff:ffff:ffff:ffff:ffff:ffff
123ffb1:7a0::/28ffb1:7af:ffff:ffff:ffff:ffff:ffff:ffff
124ffb1:7b0::/28ffb1:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125ffb1:7c0::/28ffb1:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126ffb1:7d0::/28ffb1:7df:ffff:ffff:ffff:ffff:ffff:ffff
127ffb1:7e0::/28ffb1:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128ffb1:7f0::/28ffb1:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129ffb1:800::/28ffb1:80f:ffff:ffff:ffff:ffff:ffff:ffff
130ffb1:810::/28ffb1:81f:ffff:ffff:ffff:ffff:ffff:ffff
131ffb1:820::/28ffb1:82f:ffff:ffff:ffff:ffff:ffff:ffff
132ffb1:830::/28ffb1:83f:ffff:ffff:ffff:ffff:ffff:ffff
133ffb1:840::/28ffb1:84f:ffff:ffff:ffff:ffff:ffff:ffff
134ffb1:850::/28ffb1:85f:ffff:ffff:ffff:ffff:ffff:ffff
135ffb1:860::/28ffb1:86f:ffff:ffff:ffff:ffff:ffff:ffff
136ffb1:870::/28ffb1:87f:ffff:ffff:ffff:ffff:ffff:ffff
137ffb1:880::/28ffb1:88f:ffff:ffff:ffff:ffff:ffff:ffff
138ffb1:890::/28ffb1:89f:ffff:ffff:ffff:ffff:ffff:ffff
139ffb1:8a0::/28ffb1:8af:ffff:ffff:ffff:ffff:ffff:ffff
140ffb1:8b0::/28ffb1:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141ffb1:8c0::/28ffb1:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142ffb1:8d0::/28ffb1:8df:ffff:ffff:ffff:ffff:ffff:ffff
143ffb1:8e0::/28ffb1:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144ffb1:8f0::/28ffb1:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145ffb1:900::/28ffb1:90f:ffff:ffff:ffff:ffff:ffff:ffff
146ffb1:910::/28ffb1:91f:ffff:ffff:ffff:ffff:ffff:ffff
147ffb1:920::/28ffb1:92f:ffff:ffff:ffff:ffff:ffff:ffff
148ffb1:930::/28ffb1:93f:ffff:ffff:ffff:ffff:ffff:ffff
149ffb1:940::/28ffb1:94f:ffff:ffff:ffff:ffff:ffff:ffff
150ffb1:950::/28ffb1:95f:ffff:ffff:ffff:ffff:ffff:ffff
151ffb1:960::/28ffb1:96f:ffff:ffff:ffff:ffff:ffff:ffff
152ffb1:970::/28ffb1:97f:ffff:ffff:ffff:ffff:ffff:ffff
153ffb1:980::/28ffb1:98f:ffff:ffff:ffff:ffff:ffff:ffff
154ffb1:990::/28ffb1:99f:ffff:ffff:ffff:ffff:ffff:ffff
155ffb1:9a0::/28ffb1:9af:ffff:ffff:ffff:ffff:ffff:ffff
156ffb1:9b0::/28ffb1:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157ffb1:9c0::/28ffb1:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158ffb1:9d0::/28ffb1:9df:ffff:ffff:ffff:ffff:ffff:ffff
159ffb1:9e0::/28ffb1:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160ffb1:9f0::/28ffb1:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161ffb1:a00::/28ffb1:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162ffb1:a10::/28ffb1:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163ffb1:a20::/28ffb1:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164ffb1:a30::/28ffb1:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165ffb1:a40::/28ffb1:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166ffb1:a50::/28ffb1:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167ffb1:a60::/28ffb1:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168ffb1:a70::/28ffb1:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169ffb1:a80::/28ffb1:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170ffb1:a90::/28ffb1:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171ffb1:aa0::/28ffb1:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172ffb1:ab0::/28ffb1:abf:ffff:ffff:ffff:ffff:ffff:ffff
173ffb1:ac0::/28ffb1:acf:ffff:ffff:ffff:ffff:ffff:ffff
174ffb1:ad0::/28ffb1:adf:ffff:ffff:ffff:ffff:ffff:ffff
175ffb1:ae0::/28ffb1:aef:ffff:ffff:ffff:ffff:ffff:ffff
176ffb1:af0::/28ffb1:aff:ffff:ffff:ffff:ffff:ffff:ffff
177ffb1:b00::/28ffb1:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178ffb1:b10::/28ffb1:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179ffb1:b20::/28ffb1:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180ffb1:b30::/28ffb1:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181ffb1:b40::/28ffb1:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182ffb1:b50::/28ffb1:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183ffb1:b60::/28ffb1:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184ffb1:b70::/28ffb1:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185ffb1:b80::/28ffb1:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186ffb1:b90::/28ffb1:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187ffb1:ba0::/28ffb1:baf:ffff:ffff:ffff:ffff:ffff:ffff
188ffb1:bb0::/28ffb1:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189ffb1:bc0::/28ffb1:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190ffb1:bd0::/28ffb1:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191ffb1:be0::/28ffb1:bef:ffff:ffff:ffff:ffff:ffff:ffff
192ffb1:bf0::/28ffb1:bff:ffff:ffff:ffff:ffff:ffff:ffff
193ffb1:c00::/28ffb1:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194ffb1:c10::/28ffb1:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195ffb1:c20::/28ffb1:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196ffb1:c30::/28ffb1:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197ffb1:c40::/28ffb1:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198ffb1:c50::/28ffb1:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199ffb1:c60::/28ffb1:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200ffb1:c70::/28ffb1:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201ffb1:c80::/28ffb1:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202ffb1:c90::/28ffb1:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203ffb1:ca0::/28ffb1:caf:ffff:ffff:ffff:ffff:ffff:ffff
204ffb1:cb0::/28ffb1:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205ffb1:cc0::/28ffb1:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206ffb1:cd0::/28ffb1:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207ffb1:ce0::/28ffb1:cef:ffff:ffff:ffff:ffff:ffff:ffff
208ffb1:cf0::/28ffb1:cff:ffff:ffff:ffff:ffff:ffff:ffff
209ffb1:d00::/28ffb1:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210ffb1:d10::/28ffb1:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211ffb1:d20::/28ffb1:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212ffb1:d30::/28ffb1:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213ffb1:d40::/28ffb1:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214ffb1:d50::/28ffb1:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215ffb1:d60::/28ffb1:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216ffb1:d70::/28ffb1:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217ffb1:d80::/28ffb1:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218ffb1:d90::/28ffb1:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219ffb1:da0::/28ffb1:daf:ffff:ffff:ffff:ffff:ffff:ffff
220ffb1:db0::/28ffb1:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221ffb1:dc0::/28ffb1:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222ffb1:dd0::/28ffb1:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223ffb1:de0::/28ffb1:def:ffff:ffff:ffff:ffff:ffff:ffff
224ffb1:df0::/28ffb1:dff:ffff:ffff:ffff:ffff:ffff:ffff
225ffb1:e00::/28ffb1:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226ffb1:e10::/28ffb1:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227ffb1:e20::/28ffb1:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228ffb1:e30::/28ffb1:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229ffb1:e40::/28ffb1:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230ffb1:e50::/28ffb1:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231ffb1:e60::/28ffb1:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232ffb1:e70::/28ffb1:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233ffb1:e80::/28ffb1:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234ffb1:e90::/28ffb1:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235ffb1:ea0::/28ffb1:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236ffb1:eb0::/28ffb1:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237ffb1:ec0::/28ffb1:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238ffb1:ed0::/28ffb1:edf:ffff:ffff:ffff:ffff:ffff:ffff
239ffb1:ee0::/28ffb1:eef:ffff:ffff:ffff:ffff:ffff:ffff
240ffb1:ef0::/28ffb1:eff:ffff:ffff:ffff:ffff:ffff:ffff
241ffb1:f00::/28ffb1:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242ffb1:f10::/28ffb1:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243ffb1:f20::/28ffb1:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244ffb1:f30::/28ffb1:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245ffb1:f40::/28ffb1:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246ffb1:f50::/28ffb1:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247ffb1:f60::/28ffb1:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248ffb1:f70::/28ffb1:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249ffb1:f80::/28ffb1:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250ffb1:f90::/28ffb1:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251ffb1:fa0::/28ffb1:faf:ffff:ffff:ffff:ffff:ffff:ffff
252ffb1:fb0::/28ffb1:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253ffb1:fc0::/28ffb1:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254ffb1:fd0::/28ffb1:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255ffb1:fe0::/28ffb1:fef:ffff:ffff:ffff:ffff:ffff:ffff
256ffb1:ff0::/28ffb1: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.