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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/20
Addresses2^108
/64 networks2^44
Network
fc0f:1000::/20
First address
fc0f:1000::
Last address
fc0f:1fff: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
fc0f:1000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
1.f.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)

fc0f:1000::/20 makes 256 subnets of /28.

Subnets
#SubnetLast address
1fc0f:1000::/28fc0f:100f:ffff:ffff:ffff:ffff:ffff:ffff
2fc0f:1010::/28fc0f:101f:ffff:ffff:ffff:ffff:ffff:ffff
3fc0f:1020::/28fc0f:102f:ffff:ffff:ffff:ffff:ffff:ffff
4fc0f:1030::/28fc0f:103f:ffff:ffff:ffff:ffff:ffff:ffff
5fc0f:1040::/28fc0f:104f:ffff:ffff:ffff:ffff:ffff:ffff
6fc0f:1050::/28fc0f:105f:ffff:ffff:ffff:ffff:ffff:ffff
7fc0f:1060::/28fc0f:106f:ffff:ffff:ffff:ffff:ffff:ffff
8fc0f:1070::/28fc0f:107f:ffff:ffff:ffff:ffff:ffff:ffff
9fc0f:1080::/28fc0f:108f:ffff:ffff:ffff:ffff:ffff:ffff
10fc0f:1090::/28fc0f:109f:ffff:ffff:ffff:ffff:ffff:ffff
11fc0f:10a0::/28fc0f:10af:ffff:ffff:ffff:ffff:ffff:ffff
12fc0f:10b0::/28fc0f:10bf:ffff:ffff:ffff:ffff:ffff:ffff
13fc0f:10c0::/28fc0f:10cf:ffff:ffff:ffff:ffff:ffff:ffff
14fc0f:10d0::/28fc0f:10df:ffff:ffff:ffff:ffff:ffff:ffff
15fc0f:10e0::/28fc0f:10ef:ffff:ffff:ffff:ffff:ffff:ffff
16fc0f:10f0::/28fc0f:10ff:ffff:ffff:ffff:ffff:ffff:ffff
17fc0f:1100::/28fc0f:110f:ffff:ffff:ffff:ffff:ffff:ffff
18fc0f:1110::/28fc0f:111f:ffff:ffff:ffff:ffff:ffff:ffff
19fc0f:1120::/28fc0f:112f:ffff:ffff:ffff:ffff:ffff:ffff
20fc0f:1130::/28fc0f:113f:ffff:ffff:ffff:ffff:ffff:ffff
21fc0f:1140::/28fc0f:114f:ffff:ffff:ffff:ffff:ffff:ffff
22fc0f:1150::/28fc0f:115f:ffff:ffff:ffff:ffff:ffff:ffff
23fc0f:1160::/28fc0f:116f:ffff:ffff:ffff:ffff:ffff:ffff
24fc0f:1170::/28fc0f:117f:ffff:ffff:ffff:ffff:ffff:ffff
25fc0f:1180::/28fc0f:118f:ffff:ffff:ffff:ffff:ffff:ffff
26fc0f:1190::/28fc0f:119f:ffff:ffff:ffff:ffff:ffff:ffff
27fc0f:11a0::/28fc0f:11af:ffff:ffff:ffff:ffff:ffff:ffff
28fc0f:11b0::/28fc0f:11bf:ffff:ffff:ffff:ffff:ffff:ffff
29fc0f:11c0::/28fc0f:11cf:ffff:ffff:ffff:ffff:ffff:ffff
30fc0f:11d0::/28fc0f:11df:ffff:ffff:ffff:ffff:ffff:ffff
31fc0f:11e0::/28fc0f:11ef:ffff:ffff:ffff:ffff:ffff:ffff
32fc0f:11f0::/28fc0f:11ff:ffff:ffff:ffff:ffff:ffff:ffff
33fc0f:1200::/28fc0f:120f:ffff:ffff:ffff:ffff:ffff:ffff
34fc0f:1210::/28fc0f:121f:ffff:ffff:ffff:ffff:ffff:ffff
35fc0f:1220::/28fc0f:122f:ffff:ffff:ffff:ffff:ffff:ffff
36fc0f:1230::/28fc0f:123f:ffff:ffff:ffff:ffff:ffff:ffff
37fc0f:1240::/28fc0f:124f:ffff:ffff:ffff:ffff:ffff:ffff
38fc0f:1250::/28fc0f:125f:ffff:ffff:ffff:ffff:ffff:ffff
39fc0f:1260::/28fc0f:126f:ffff:ffff:ffff:ffff:ffff:ffff
40fc0f:1270::/28fc0f:127f:ffff:ffff:ffff:ffff:ffff:ffff
41fc0f:1280::/28fc0f:128f:ffff:ffff:ffff:ffff:ffff:ffff
42fc0f:1290::/28fc0f:129f:ffff:ffff:ffff:ffff:ffff:ffff
43fc0f:12a0::/28fc0f:12af:ffff:ffff:ffff:ffff:ffff:ffff
44fc0f:12b0::/28fc0f:12bf:ffff:ffff:ffff:ffff:ffff:ffff
45fc0f:12c0::/28fc0f:12cf:ffff:ffff:ffff:ffff:ffff:ffff
46fc0f:12d0::/28fc0f:12df:ffff:ffff:ffff:ffff:ffff:ffff
47fc0f:12e0::/28fc0f:12ef:ffff:ffff:ffff:ffff:ffff:ffff
48fc0f:12f0::/28fc0f:12ff:ffff:ffff:ffff:ffff:ffff:ffff
49fc0f:1300::/28fc0f:130f:ffff:ffff:ffff:ffff:ffff:ffff
50fc0f:1310::/28fc0f:131f:ffff:ffff:ffff:ffff:ffff:ffff
51fc0f:1320::/28fc0f:132f:ffff:ffff:ffff:ffff:ffff:ffff
52fc0f:1330::/28fc0f:133f:ffff:ffff:ffff:ffff:ffff:ffff
53fc0f:1340::/28fc0f:134f:ffff:ffff:ffff:ffff:ffff:ffff
54fc0f:1350::/28fc0f:135f:ffff:ffff:ffff:ffff:ffff:ffff
55fc0f:1360::/28fc0f:136f:ffff:ffff:ffff:ffff:ffff:ffff
56fc0f:1370::/28fc0f:137f:ffff:ffff:ffff:ffff:ffff:ffff
57fc0f:1380::/28fc0f:138f:ffff:ffff:ffff:ffff:ffff:ffff
58fc0f:1390::/28fc0f:139f:ffff:ffff:ffff:ffff:ffff:ffff
59fc0f:13a0::/28fc0f:13af:ffff:ffff:ffff:ffff:ffff:ffff
60fc0f:13b0::/28fc0f:13bf:ffff:ffff:ffff:ffff:ffff:ffff
61fc0f:13c0::/28fc0f:13cf:ffff:ffff:ffff:ffff:ffff:ffff
62fc0f:13d0::/28fc0f:13df:ffff:ffff:ffff:ffff:ffff:ffff
63fc0f:13e0::/28fc0f:13ef:ffff:ffff:ffff:ffff:ffff:ffff
64fc0f:13f0::/28fc0f:13ff:ffff:ffff:ffff:ffff:ffff:ffff
65fc0f:1400::/28fc0f:140f:ffff:ffff:ffff:ffff:ffff:ffff
66fc0f:1410::/28fc0f:141f:ffff:ffff:ffff:ffff:ffff:ffff
67fc0f:1420::/28fc0f:142f:ffff:ffff:ffff:ffff:ffff:ffff
68fc0f:1430::/28fc0f:143f:ffff:ffff:ffff:ffff:ffff:ffff
69fc0f:1440::/28fc0f:144f:ffff:ffff:ffff:ffff:ffff:ffff
70fc0f:1450::/28fc0f:145f:ffff:ffff:ffff:ffff:ffff:ffff
71fc0f:1460::/28fc0f:146f:ffff:ffff:ffff:ffff:ffff:ffff
72fc0f:1470::/28fc0f:147f:ffff:ffff:ffff:ffff:ffff:ffff
73fc0f:1480::/28fc0f:148f:ffff:ffff:ffff:ffff:ffff:ffff
74fc0f:1490::/28fc0f:149f:ffff:ffff:ffff:ffff:ffff:ffff
75fc0f:14a0::/28fc0f:14af:ffff:ffff:ffff:ffff:ffff:ffff
76fc0f:14b0::/28fc0f:14bf:ffff:ffff:ffff:ffff:ffff:ffff
77fc0f:14c0::/28fc0f:14cf:ffff:ffff:ffff:ffff:ffff:ffff
78fc0f:14d0::/28fc0f:14df:ffff:ffff:ffff:ffff:ffff:ffff
79fc0f:14e0::/28fc0f:14ef:ffff:ffff:ffff:ffff:ffff:ffff
80fc0f:14f0::/28fc0f:14ff:ffff:ffff:ffff:ffff:ffff:ffff
81fc0f:1500::/28fc0f:150f:ffff:ffff:ffff:ffff:ffff:ffff
82fc0f:1510::/28fc0f:151f:ffff:ffff:ffff:ffff:ffff:ffff
83fc0f:1520::/28fc0f:152f:ffff:ffff:ffff:ffff:ffff:ffff
84fc0f:1530::/28fc0f:153f:ffff:ffff:ffff:ffff:ffff:ffff
85fc0f:1540::/28fc0f:154f:ffff:ffff:ffff:ffff:ffff:ffff
86fc0f:1550::/28fc0f:155f:ffff:ffff:ffff:ffff:ffff:ffff
87fc0f:1560::/28fc0f:156f:ffff:ffff:ffff:ffff:ffff:ffff
88fc0f:1570::/28fc0f:157f:ffff:ffff:ffff:ffff:ffff:ffff
89fc0f:1580::/28fc0f:158f:ffff:ffff:ffff:ffff:ffff:ffff
90fc0f:1590::/28fc0f:159f:ffff:ffff:ffff:ffff:ffff:ffff
91fc0f:15a0::/28fc0f:15af:ffff:ffff:ffff:ffff:ffff:ffff
92fc0f:15b0::/28fc0f:15bf:ffff:ffff:ffff:ffff:ffff:ffff
93fc0f:15c0::/28fc0f:15cf:ffff:ffff:ffff:ffff:ffff:ffff
94fc0f:15d0::/28fc0f:15df:ffff:ffff:ffff:ffff:ffff:ffff
95fc0f:15e0::/28fc0f:15ef:ffff:ffff:ffff:ffff:ffff:ffff
96fc0f:15f0::/28fc0f:15ff:ffff:ffff:ffff:ffff:ffff:ffff
97fc0f:1600::/28fc0f:160f:ffff:ffff:ffff:ffff:ffff:ffff
98fc0f:1610::/28fc0f:161f:ffff:ffff:ffff:ffff:ffff:ffff
99fc0f:1620::/28fc0f:162f:ffff:ffff:ffff:ffff:ffff:ffff
100fc0f:1630::/28fc0f:163f:ffff:ffff:ffff:ffff:ffff:ffff
101fc0f:1640::/28fc0f:164f:ffff:ffff:ffff:ffff:ffff:ffff
102fc0f:1650::/28fc0f:165f:ffff:ffff:ffff:ffff:ffff:ffff
103fc0f:1660::/28fc0f:166f:ffff:ffff:ffff:ffff:ffff:ffff
104fc0f:1670::/28fc0f:167f:ffff:ffff:ffff:ffff:ffff:ffff
105fc0f:1680::/28fc0f:168f:ffff:ffff:ffff:ffff:ffff:ffff
106fc0f:1690::/28fc0f:169f:ffff:ffff:ffff:ffff:ffff:ffff
107fc0f:16a0::/28fc0f:16af:ffff:ffff:ffff:ffff:ffff:ffff
108fc0f:16b0::/28fc0f:16bf:ffff:ffff:ffff:ffff:ffff:ffff
109fc0f:16c0::/28fc0f:16cf:ffff:ffff:ffff:ffff:ffff:ffff
110fc0f:16d0::/28fc0f:16df:ffff:ffff:ffff:ffff:ffff:ffff
111fc0f:16e0::/28fc0f:16ef:ffff:ffff:ffff:ffff:ffff:ffff
112fc0f:16f0::/28fc0f:16ff:ffff:ffff:ffff:ffff:ffff:ffff
113fc0f:1700::/28fc0f:170f:ffff:ffff:ffff:ffff:ffff:ffff
114fc0f:1710::/28fc0f:171f:ffff:ffff:ffff:ffff:ffff:ffff
115fc0f:1720::/28fc0f:172f:ffff:ffff:ffff:ffff:ffff:ffff
116fc0f:1730::/28fc0f:173f:ffff:ffff:ffff:ffff:ffff:ffff
117fc0f:1740::/28fc0f:174f:ffff:ffff:ffff:ffff:ffff:ffff
118fc0f:1750::/28fc0f:175f:ffff:ffff:ffff:ffff:ffff:ffff
119fc0f:1760::/28fc0f:176f:ffff:ffff:ffff:ffff:ffff:ffff
120fc0f:1770::/28fc0f:177f:ffff:ffff:ffff:ffff:ffff:ffff
121fc0f:1780::/28fc0f:178f:ffff:ffff:ffff:ffff:ffff:ffff
122fc0f:1790::/28fc0f:179f:ffff:ffff:ffff:ffff:ffff:ffff
123fc0f:17a0::/28fc0f:17af:ffff:ffff:ffff:ffff:ffff:ffff
124fc0f:17b0::/28fc0f:17bf:ffff:ffff:ffff:ffff:ffff:ffff
125fc0f:17c0::/28fc0f:17cf:ffff:ffff:ffff:ffff:ffff:ffff
126fc0f:17d0::/28fc0f:17df:ffff:ffff:ffff:ffff:ffff:ffff
127fc0f:17e0::/28fc0f:17ef:ffff:ffff:ffff:ffff:ffff:ffff
128fc0f:17f0::/28fc0f:17ff:ffff:ffff:ffff:ffff:ffff:ffff
129fc0f:1800::/28fc0f:180f:ffff:ffff:ffff:ffff:ffff:ffff
130fc0f:1810::/28fc0f:181f:ffff:ffff:ffff:ffff:ffff:ffff
131fc0f:1820::/28fc0f:182f:ffff:ffff:ffff:ffff:ffff:ffff
132fc0f:1830::/28fc0f:183f:ffff:ffff:ffff:ffff:ffff:ffff
133fc0f:1840::/28fc0f:184f:ffff:ffff:ffff:ffff:ffff:ffff
134fc0f:1850::/28fc0f:185f:ffff:ffff:ffff:ffff:ffff:ffff
135fc0f:1860::/28fc0f:186f:ffff:ffff:ffff:ffff:ffff:ffff
136fc0f:1870::/28fc0f:187f:ffff:ffff:ffff:ffff:ffff:ffff
137fc0f:1880::/28fc0f:188f:ffff:ffff:ffff:ffff:ffff:ffff
138fc0f:1890::/28fc0f:189f:ffff:ffff:ffff:ffff:ffff:ffff
139fc0f:18a0::/28fc0f:18af:ffff:ffff:ffff:ffff:ffff:ffff
140fc0f:18b0::/28fc0f:18bf:ffff:ffff:ffff:ffff:ffff:ffff
141fc0f:18c0::/28fc0f:18cf:ffff:ffff:ffff:ffff:ffff:ffff
142fc0f:18d0::/28fc0f:18df:ffff:ffff:ffff:ffff:ffff:ffff
143fc0f:18e0::/28fc0f:18ef:ffff:ffff:ffff:ffff:ffff:ffff
144fc0f:18f0::/28fc0f:18ff:ffff:ffff:ffff:ffff:ffff:ffff
145fc0f:1900::/28fc0f:190f:ffff:ffff:ffff:ffff:ffff:ffff
146fc0f:1910::/28fc0f:191f:ffff:ffff:ffff:ffff:ffff:ffff
147fc0f:1920::/28fc0f:192f:ffff:ffff:ffff:ffff:ffff:ffff
148fc0f:1930::/28fc0f:193f:ffff:ffff:ffff:ffff:ffff:ffff
149fc0f:1940::/28fc0f:194f:ffff:ffff:ffff:ffff:ffff:ffff
150fc0f:1950::/28fc0f:195f:ffff:ffff:ffff:ffff:ffff:ffff
151fc0f:1960::/28fc0f:196f:ffff:ffff:ffff:ffff:ffff:ffff
152fc0f:1970::/28fc0f:197f:ffff:ffff:ffff:ffff:ffff:ffff
153fc0f:1980::/28fc0f:198f:ffff:ffff:ffff:ffff:ffff:ffff
154fc0f:1990::/28fc0f:199f:ffff:ffff:ffff:ffff:ffff:ffff
155fc0f:19a0::/28fc0f:19af:ffff:ffff:ffff:ffff:ffff:ffff
156fc0f:19b0::/28fc0f:19bf:ffff:ffff:ffff:ffff:ffff:ffff
157fc0f:19c0::/28fc0f:19cf:ffff:ffff:ffff:ffff:ffff:ffff
158fc0f:19d0::/28fc0f:19df:ffff:ffff:ffff:ffff:ffff:ffff
159fc0f:19e0::/28fc0f:19ef:ffff:ffff:ffff:ffff:ffff:ffff
160fc0f:19f0::/28fc0f:19ff:ffff:ffff:ffff:ffff:ffff:ffff
161fc0f:1a00::/28fc0f:1a0f:ffff:ffff:ffff:ffff:ffff:ffff
162fc0f:1a10::/28fc0f:1a1f:ffff:ffff:ffff:ffff:ffff:ffff
163fc0f:1a20::/28fc0f:1a2f:ffff:ffff:ffff:ffff:ffff:ffff
164fc0f:1a30::/28fc0f:1a3f:ffff:ffff:ffff:ffff:ffff:ffff
165fc0f:1a40::/28fc0f:1a4f:ffff:ffff:ffff:ffff:ffff:ffff
166fc0f:1a50::/28fc0f:1a5f:ffff:ffff:ffff:ffff:ffff:ffff
167fc0f:1a60::/28fc0f:1a6f:ffff:ffff:ffff:ffff:ffff:ffff
168fc0f:1a70::/28fc0f:1a7f:ffff:ffff:ffff:ffff:ffff:ffff
169fc0f:1a80::/28fc0f:1a8f:ffff:ffff:ffff:ffff:ffff:ffff
170fc0f:1a90::/28fc0f:1a9f:ffff:ffff:ffff:ffff:ffff:ffff
171fc0f:1aa0::/28fc0f:1aaf:ffff:ffff:ffff:ffff:ffff:ffff
172fc0f:1ab0::/28fc0f:1abf:ffff:ffff:ffff:ffff:ffff:ffff
173fc0f:1ac0::/28fc0f:1acf:ffff:ffff:ffff:ffff:ffff:ffff
174fc0f:1ad0::/28fc0f:1adf:ffff:ffff:ffff:ffff:ffff:ffff
175fc0f:1ae0::/28fc0f:1aef:ffff:ffff:ffff:ffff:ffff:ffff
176fc0f:1af0::/28fc0f:1aff:ffff:ffff:ffff:ffff:ffff:ffff
177fc0f:1b00::/28fc0f:1b0f:ffff:ffff:ffff:ffff:ffff:ffff
178fc0f:1b10::/28fc0f:1b1f:ffff:ffff:ffff:ffff:ffff:ffff
179fc0f:1b20::/28fc0f:1b2f:ffff:ffff:ffff:ffff:ffff:ffff
180fc0f:1b30::/28fc0f:1b3f:ffff:ffff:ffff:ffff:ffff:ffff
181fc0f:1b40::/28fc0f:1b4f:ffff:ffff:ffff:ffff:ffff:ffff
182fc0f:1b50::/28fc0f:1b5f:ffff:ffff:ffff:ffff:ffff:ffff
183fc0f:1b60::/28fc0f:1b6f:ffff:ffff:ffff:ffff:ffff:ffff
184fc0f:1b70::/28fc0f:1b7f:ffff:ffff:ffff:ffff:ffff:ffff
185fc0f:1b80::/28fc0f:1b8f:ffff:ffff:ffff:ffff:ffff:ffff
186fc0f:1b90::/28fc0f:1b9f:ffff:ffff:ffff:ffff:ffff:ffff
187fc0f:1ba0::/28fc0f:1baf:ffff:ffff:ffff:ffff:ffff:ffff
188fc0f:1bb0::/28fc0f:1bbf:ffff:ffff:ffff:ffff:ffff:ffff
189fc0f:1bc0::/28fc0f:1bcf:ffff:ffff:ffff:ffff:ffff:ffff
190fc0f:1bd0::/28fc0f:1bdf:ffff:ffff:ffff:ffff:ffff:ffff
191fc0f:1be0::/28fc0f:1bef:ffff:ffff:ffff:ffff:ffff:ffff
192fc0f:1bf0::/28fc0f:1bff:ffff:ffff:ffff:ffff:ffff:ffff
193fc0f:1c00::/28fc0f:1c0f:ffff:ffff:ffff:ffff:ffff:ffff
194fc0f:1c10::/28fc0f:1c1f:ffff:ffff:ffff:ffff:ffff:ffff
195fc0f:1c20::/28fc0f:1c2f:ffff:ffff:ffff:ffff:ffff:ffff
196fc0f:1c30::/28fc0f:1c3f:ffff:ffff:ffff:ffff:ffff:ffff
197fc0f:1c40::/28fc0f:1c4f:ffff:ffff:ffff:ffff:ffff:ffff
198fc0f:1c50::/28fc0f:1c5f:ffff:ffff:ffff:ffff:ffff:ffff
199fc0f:1c60::/28fc0f:1c6f:ffff:ffff:ffff:ffff:ffff:ffff
200fc0f:1c70::/28fc0f:1c7f:ffff:ffff:ffff:ffff:ffff:ffff
201fc0f:1c80::/28fc0f:1c8f:ffff:ffff:ffff:ffff:ffff:ffff
202fc0f:1c90::/28fc0f:1c9f:ffff:ffff:ffff:ffff:ffff:ffff
203fc0f:1ca0::/28fc0f:1caf:ffff:ffff:ffff:ffff:ffff:ffff
204fc0f:1cb0::/28fc0f:1cbf:ffff:ffff:ffff:ffff:ffff:ffff
205fc0f:1cc0::/28fc0f:1ccf:ffff:ffff:ffff:ffff:ffff:ffff
206fc0f:1cd0::/28fc0f:1cdf:ffff:ffff:ffff:ffff:ffff:ffff
207fc0f:1ce0::/28fc0f:1cef:ffff:ffff:ffff:ffff:ffff:ffff
208fc0f:1cf0::/28fc0f:1cff:ffff:ffff:ffff:ffff:ffff:ffff
209fc0f:1d00::/28fc0f:1d0f:ffff:ffff:ffff:ffff:ffff:ffff
210fc0f:1d10::/28fc0f:1d1f:ffff:ffff:ffff:ffff:ffff:ffff
211fc0f:1d20::/28fc0f:1d2f:ffff:ffff:ffff:ffff:ffff:ffff
212fc0f:1d30::/28fc0f:1d3f:ffff:ffff:ffff:ffff:ffff:ffff
213fc0f:1d40::/28fc0f:1d4f:ffff:ffff:ffff:ffff:ffff:ffff
214fc0f:1d50::/28fc0f:1d5f:ffff:ffff:ffff:ffff:ffff:ffff
215fc0f:1d60::/28fc0f:1d6f:ffff:ffff:ffff:ffff:ffff:ffff
216fc0f:1d70::/28fc0f:1d7f:ffff:ffff:ffff:ffff:ffff:ffff
217fc0f:1d80::/28fc0f:1d8f:ffff:ffff:ffff:ffff:ffff:ffff
218fc0f:1d90::/28fc0f:1d9f:ffff:ffff:ffff:ffff:ffff:ffff
219fc0f:1da0::/28fc0f:1daf:ffff:ffff:ffff:ffff:ffff:ffff
220fc0f:1db0::/28fc0f:1dbf:ffff:ffff:ffff:ffff:ffff:ffff
221fc0f:1dc0::/28fc0f:1dcf:ffff:ffff:ffff:ffff:ffff:ffff
222fc0f:1dd0::/28fc0f:1ddf:ffff:ffff:ffff:ffff:ffff:ffff
223fc0f:1de0::/28fc0f:1def:ffff:ffff:ffff:ffff:ffff:ffff
224fc0f:1df0::/28fc0f:1dff:ffff:ffff:ffff:ffff:ffff:ffff
225fc0f:1e00::/28fc0f:1e0f:ffff:ffff:ffff:ffff:ffff:ffff
226fc0f:1e10::/28fc0f:1e1f:ffff:ffff:ffff:ffff:ffff:ffff
227fc0f:1e20::/28fc0f:1e2f:ffff:ffff:ffff:ffff:ffff:ffff
228fc0f:1e30::/28fc0f:1e3f:ffff:ffff:ffff:ffff:ffff:ffff
229fc0f:1e40::/28fc0f:1e4f:ffff:ffff:ffff:ffff:ffff:ffff
230fc0f:1e50::/28fc0f:1e5f:ffff:ffff:ffff:ffff:ffff:ffff
231fc0f:1e60::/28fc0f:1e6f:ffff:ffff:ffff:ffff:ffff:ffff
232fc0f:1e70::/28fc0f:1e7f:ffff:ffff:ffff:ffff:ffff:ffff
233fc0f:1e80::/28fc0f:1e8f:ffff:ffff:ffff:ffff:ffff:ffff
234fc0f:1e90::/28fc0f:1e9f:ffff:ffff:ffff:ffff:ffff:ffff
235fc0f:1ea0::/28fc0f:1eaf:ffff:ffff:ffff:ffff:ffff:ffff
236fc0f:1eb0::/28fc0f:1ebf:ffff:ffff:ffff:ffff:ffff:ffff
237fc0f:1ec0::/28fc0f:1ecf:ffff:ffff:ffff:ffff:ffff:ffff
238fc0f:1ed0::/28fc0f:1edf:ffff:ffff:ffff:ffff:ffff:ffff
239fc0f:1ee0::/28fc0f:1eef:ffff:ffff:ffff:ffff:ffff:ffff
240fc0f:1ef0::/28fc0f:1eff:ffff:ffff:ffff:ffff:ffff:ffff
241fc0f:1f00::/28fc0f:1f0f:ffff:ffff:ffff:ffff:ffff:ffff
242fc0f:1f10::/28fc0f:1f1f:ffff:ffff:ffff:ffff:ffff:ffff
243fc0f:1f20::/28fc0f:1f2f:ffff:ffff:ffff:ffff:ffff:ffff
244fc0f:1f30::/28fc0f:1f3f:ffff:ffff:ffff:ffff:ffff:ffff
245fc0f:1f40::/28fc0f:1f4f:ffff:ffff:ffff:ffff:ffff:ffff
246fc0f:1f50::/28fc0f:1f5f:ffff:ffff:ffff:ffff:ffff:ffff
247fc0f:1f60::/28fc0f:1f6f:ffff:ffff:ffff:ffff:ffff:ffff
248fc0f:1f70::/28fc0f:1f7f:ffff:ffff:ffff:ffff:ffff:ffff
249fc0f:1f80::/28fc0f:1f8f:ffff:ffff:ffff:ffff:ffff:ffff
250fc0f:1f90::/28fc0f:1f9f:ffff:ffff:ffff:ffff:ffff:ffff
251fc0f:1fa0::/28fc0f:1faf:ffff:ffff:ffff:ffff:ffff:ffff
252fc0f:1fb0::/28fc0f:1fbf:ffff:ffff:ffff:ffff:ffff:ffff
253fc0f:1fc0::/28fc0f:1fcf:ffff:ffff:ffff:ffff:ffff:ffff
254fc0f:1fd0::/28fc0f:1fdf:ffff:ffff:ffff:ffff:ffff:ffff
255fc0f:1fe0::/28fc0f:1fef:ffff:ffff:ffff:ffff:ffff:ffff
256fc0f:1ff0::/28fc0f:1fff: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.