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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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Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

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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
ff01:2000::/20
First address
ff01:2000::
Last address
ff01:2fff: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
ff01:2000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
2.1.0.f.f.ip6.arpa
Split into smaller subnets/32
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

ff01:2000::/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1ff01:2000::/32ff01:2000:ffff:ffff:ffff:ffff:ffff:ffff
2ff01:2001::/32ff01:2001:ffff:ffff:ffff:ffff:ffff:ffff
3ff01:2002::/32ff01:2002:ffff:ffff:ffff:ffff:ffff:ffff
4ff01:2003::/32ff01:2003:ffff:ffff:ffff:ffff:ffff:ffff
5ff01:2004::/32ff01:2004:ffff:ffff:ffff:ffff:ffff:ffff
6ff01:2005::/32ff01:2005:ffff:ffff:ffff:ffff:ffff:ffff
7ff01:2006::/32ff01:2006:ffff:ffff:ffff:ffff:ffff:ffff
8ff01:2007::/32ff01:2007:ffff:ffff:ffff:ffff:ffff:ffff
9ff01:2008::/32ff01:2008:ffff:ffff:ffff:ffff:ffff:ffff
10ff01:2009::/32ff01:2009:ffff:ffff:ffff:ffff:ffff:ffff
11ff01:200a::/32ff01:200a:ffff:ffff:ffff:ffff:ffff:ffff
12ff01:200b::/32ff01:200b:ffff:ffff:ffff:ffff:ffff:ffff
13ff01:200c::/32ff01:200c:ffff:ffff:ffff:ffff:ffff:ffff
14ff01:200d::/32ff01:200d:ffff:ffff:ffff:ffff:ffff:ffff
15ff01:200e::/32ff01:200e:ffff:ffff:ffff:ffff:ffff:ffff
16ff01:200f::/32ff01:200f:ffff:ffff:ffff:ffff:ffff:ffff
17ff01:2010::/32ff01:2010:ffff:ffff:ffff:ffff:ffff:ffff
18ff01:2011::/32ff01:2011:ffff:ffff:ffff:ffff:ffff:ffff
19ff01:2012::/32ff01:2012:ffff:ffff:ffff:ffff:ffff:ffff
20ff01:2013::/32ff01:2013:ffff:ffff:ffff:ffff:ffff:ffff
21ff01:2014::/32ff01:2014:ffff:ffff:ffff:ffff:ffff:ffff
22ff01:2015::/32ff01:2015:ffff:ffff:ffff:ffff:ffff:ffff
23ff01:2016::/32ff01:2016:ffff:ffff:ffff:ffff:ffff:ffff
24ff01:2017::/32ff01:2017:ffff:ffff:ffff:ffff:ffff:ffff
25ff01:2018::/32ff01:2018:ffff:ffff:ffff:ffff:ffff:ffff
26ff01:2019::/32ff01:2019:ffff:ffff:ffff:ffff:ffff:ffff
27ff01:201a::/32ff01:201a:ffff:ffff:ffff:ffff:ffff:ffff
28ff01:201b::/32ff01:201b:ffff:ffff:ffff:ffff:ffff:ffff
29ff01:201c::/32ff01:201c:ffff:ffff:ffff:ffff:ffff:ffff
30ff01:201d::/32ff01:201d:ffff:ffff:ffff:ffff:ffff:ffff
31ff01:201e::/32ff01:201e:ffff:ffff:ffff:ffff:ffff:ffff
32ff01:201f::/32ff01:201f:ffff:ffff:ffff:ffff:ffff:ffff
33ff01:2020::/32ff01:2020:ffff:ffff:ffff:ffff:ffff:ffff
34ff01:2021::/32ff01:2021:ffff:ffff:ffff:ffff:ffff:ffff
35ff01:2022::/32ff01:2022:ffff:ffff:ffff:ffff:ffff:ffff
36ff01:2023::/32ff01:2023:ffff:ffff:ffff:ffff:ffff:ffff
37ff01:2024::/32ff01:2024:ffff:ffff:ffff:ffff:ffff:ffff
38ff01:2025::/32ff01:2025:ffff:ffff:ffff:ffff:ffff:ffff
39ff01:2026::/32ff01:2026:ffff:ffff:ffff:ffff:ffff:ffff
40ff01:2027::/32ff01:2027:ffff:ffff:ffff:ffff:ffff:ffff
41ff01:2028::/32ff01:2028:ffff:ffff:ffff:ffff:ffff:ffff
42ff01:2029::/32ff01:2029:ffff:ffff:ffff:ffff:ffff:ffff
43ff01:202a::/32ff01:202a:ffff:ffff:ffff:ffff:ffff:ffff
44ff01:202b::/32ff01:202b:ffff:ffff:ffff:ffff:ffff:ffff
45ff01:202c::/32ff01:202c:ffff:ffff:ffff:ffff:ffff:ffff
46ff01:202d::/32ff01:202d:ffff:ffff:ffff:ffff:ffff:ffff
47ff01:202e::/32ff01:202e:ffff:ffff:ffff:ffff:ffff:ffff
48ff01:202f::/32ff01:202f:ffff:ffff:ffff:ffff:ffff:ffff
49ff01:2030::/32ff01:2030:ffff:ffff:ffff:ffff:ffff:ffff
50ff01:2031::/32ff01:2031:ffff:ffff:ffff:ffff:ffff:ffff
51ff01:2032::/32ff01:2032:ffff:ffff:ffff:ffff:ffff:ffff
52ff01:2033::/32ff01:2033:ffff:ffff:ffff:ffff:ffff:ffff
53ff01:2034::/32ff01:2034:ffff:ffff:ffff:ffff:ffff:ffff
54ff01:2035::/32ff01:2035:ffff:ffff:ffff:ffff:ffff:ffff
55ff01:2036::/32ff01:2036:ffff:ffff:ffff:ffff:ffff:ffff
56ff01:2037::/32ff01:2037:ffff:ffff:ffff:ffff:ffff:ffff
57ff01:2038::/32ff01:2038:ffff:ffff:ffff:ffff:ffff:ffff
58ff01:2039::/32ff01:2039:ffff:ffff:ffff:ffff:ffff:ffff
59ff01:203a::/32ff01:203a:ffff:ffff:ffff:ffff:ffff:ffff
60ff01:203b::/32ff01:203b:ffff:ffff:ffff:ffff:ffff:ffff
61ff01:203c::/32ff01:203c:ffff:ffff:ffff:ffff:ffff:ffff
62ff01:203d::/32ff01:203d:ffff:ffff:ffff:ffff:ffff:ffff
63ff01:203e::/32ff01:203e:ffff:ffff:ffff:ffff:ffff:ffff
64ff01:203f::/32ff01:203f:ffff:ffff:ffff:ffff:ffff:ffff
65ff01:2040::/32ff01:2040:ffff:ffff:ffff:ffff:ffff:ffff
66ff01:2041::/32ff01:2041:ffff:ffff:ffff:ffff:ffff:ffff
67ff01:2042::/32ff01:2042:ffff:ffff:ffff:ffff:ffff:ffff
68ff01:2043::/32ff01:2043:ffff:ffff:ffff:ffff:ffff:ffff
69ff01:2044::/32ff01:2044:ffff:ffff:ffff:ffff:ffff:ffff
70ff01:2045::/32ff01:2045:ffff:ffff:ffff:ffff:ffff:ffff
71ff01:2046::/32ff01:2046:ffff:ffff:ffff:ffff:ffff:ffff
72ff01:2047::/32ff01:2047:ffff:ffff:ffff:ffff:ffff:ffff
73ff01:2048::/32ff01:2048:ffff:ffff:ffff:ffff:ffff:ffff
74ff01:2049::/32ff01:2049:ffff:ffff:ffff:ffff:ffff:ffff
75ff01:204a::/32ff01:204a:ffff:ffff:ffff:ffff:ffff:ffff
76ff01:204b::/32ff01:204b:ffff:ffff:ffff:ffff:ffff:ffff
77ff01:204c::/32ff01:204c:ffff:ffff:ffff:ffff:ffff:ffff
78ff01:204d::/32ff01:204d:ffff:ffff:ffff:ffff:ffff:ffff
79ff01:204e::/32ff01:204e:ffff:ffff:ffff:ffff:ffff:ffff
80ff01:204f::/32ff01:204f:ffff:ffff:ffff:ffff:ffff:ffff
81ff01:2050::/32ff01:2050:ffff:ffff:ffff:ffff:ffff:ffff
82ff01:2051::/32ff01:2051:ffff:ffff:ffff:ffff:ffff:ffff
83ff01:2052::/32ff01:2052:ffff:ffff:ffff:ffff:ffff:ffff
84ff01:2053::/32ff01:2053:ffff:ffff:ffff:ffff:ffff:ffff
85ff01:2054::/32ff01:2054:ffff:ffff:ffff:ffff:ffff:ffff
86ff01:2055::/32ff01:2055:ffff:ffff:ffff:ffff:ffff:ffff
87ff01:2056::/32ff01:2056:ffff:ffff:ffff:ffff:ffff:ffff
88ff01:2057::/32ff01:2057:ffff:ffff:ffff:ffff:ffff:ffff
89ff01:2058::/32ff01:2058:ffff:ffff:ffff:ffff:ffff:ffff
90ff01:2059::/32ff01:2059:ffff:ffff:ffff:ffff:ffff:ffff
91ff01:205a::/32ff01:205a:ffff:ffff:ffff:ffff:ffff:ffff
92ff01:205b::/32ff01:205b:ffff:ffff:ffff:ffff:ffff:ffff
93ff01:205c::/32ff01:205c:ffff:ffff:ffff:ffff:ffff:ffff
94ff01:205d::/32ff01:205d:ffff:ffff:ffff:ffff:ffff:ffff
95ff01:205e::/32ff01:205e:ffff:ffff:ffff:ffff:ffff:ffff
96ff01:205f::/32ff01:205f:ffff:ffff:ffff:ffff:ffff:ffff
97ff01:2060::/32ff01:2060:ffff:ffff:ffff:ffff:ffff:ffff
98ff01:2061::/32ff01:2061:ffff:ffff:ffff:ffff:ffff:ffff
99ff01:2062::/32ff01:2062:ffff:ffff:ffff:ffff:ffff:ffff
100ff01:2063::/32ff01:2063:ffff:ffff:ffff:ffff:ffff:ffff
101ff01:2064::/32ff01:2064:ffff:ffff:ffff:ffff:ffff:ffff
102ff01:2065::/32ff01:2065:ffff:ffff:ffff:ffff:ffff:ffff
103ff01:2066::/32ff01:2066:ffff:ffff:ffff:ffff:ffff:ffff
104ff01:2067::/32ff01:2067:ffff:ffff:ffff:ffff:ffff:ffff
105ff01:2068::/32ff01:2068:ffff:ffff:ffff:ffff:ffff:ffff
106ff01:2069::/32ff01:2069:ffff:ffff:ffff:ffff:ffff:ffff
107ff01:206a::/32ff01:206a:ffff:ffff:ffff:ffff:ffff:ffff
108ff01:206b::/32ff01:206b:ffff:ffff:ffff:ffff:ffff:ffff
109ff01:206c::/32ff01:206c:ffff:ffff:ffff:ffff:ffff:ffff
110ff01:206d::/32ff01:206d:ffff:ffff:ffff:ffff:ffff:ffff
111ff01:206e::/32ff01:206e:ffff:ffff:ffff:ffff:ffff:ffff
112ff01:206f::/32ff01:206f:ffff:ffff:ffff:ffff:ffff:ffff
113ff01:2070::/32ff01:2070:ffff:ffff:ffff:ffff:ffff:ffff
114ff01:2071::/32ff01:2071:ffff:ffff:ffff:ffff:ffff:ffff
115ff01:2072::/32ff01:2072:ffff:ffff:ffff:ffff:ffff:ffff
116ff01:2073::/32ff01:2073:ffff:ffff:ffff:ffff:ffff:ffff
117ff01:2074::/32ff01:2074:ffff:ffff:ffff:ffff:ffff:ffff
118ff01:2075::/32ff01:2075:ffff:ffff:ffff:ffff:ffff:ffff
119ff01:2076::/32ff01:2076:ffff:ffff:ffff:ffff:ffff:ffff
120ff01:2077::/32ff01:2077:ffff:ffff:ffff:ffff:ffff:ffff
121ff01:2078::/32ff01:2078:ffff:ffff:ffff:ffff:ffff:ffff
122ff01:2079::/32ff01:2079:ffff:ffff:ffff:ffff:ffff:ffff
123ff01:207a::/32ff01:207a:ffff:ffff:ffff:ffff:ffff:ffff
124ff01:207b::/32ff01:207b:ffff:ffff:ffff:ffff:ffff:ffff
125ff01:207c::/32ff01:207c:ffff:ffff:ffff:ffff:ffff:ffff
126ff01:207d::/32ff01:207d:ffff:ffff:ffff:ffff:ffff:ffff
127ff01:207e::/32ff01:207e:ffff:ffff:ffff:ffff:ffff:ffff
128ff01:207f::/32ff01:207f:ffff:ffff:ffff:ffff:ffff:ffff
129ff01:2080::/32ff01:2080:ffff:ffff:ffff:ffff:ffff:ffff
130ff01:2081::/32ff01:2081:ffff:ffff:ffff:ffff:ffff:ffff
131ff01:2082::/32ff01:2082:ffff:ffff:ffff:ffff:ffff:ffff
132ff01:2083::/32ff01:2083:ffff:ffff:ffff:ffff:ffff:ffff
133ff01:2084::/32ff01:2084:ffff:ffff:ffff:ffff:ffff:ffff
134ff01:2085::/32ff01:2085:ffff:ffff:ffff:ffff:ffff:ffff
135ff01:2086::/32ff01:2086:ffff:ffff:ffff:ffff:ffff:ffff
136ff01:2087::/32ff01:2087:ffff:ffff:ffff:ffff:ffff:ffff
137ff01:2088::/32ff01:2088:ffff:ffff:ffff:ffff:ffff:ffff
138ff01:2089::/32ff01:2089:ffff:ffff:ffff:ffff:ffff:ffff
139ff01:208a::/32ff01:208a:ffff:ffff:ffff:ffff:ffff:ffff
140ff01:208b::/32ff01:208b:ffff:ffff:ffff:ffff:ffff:ffff
141ff01:208c::/32ff01:208c:ffff:ffff:ffff:ffff:ffff:ffff
142ff01:208d::/32ff01:208d:ffff:ffff:ffff:ffff:ffff:ffff
143ff01:208e::/32ff01:208e:ffff:ffff:ffff:ffff:ffff:ffff
144ff01:208f::/32ff01:208f:ffff:ffff:ffff:ffff:ffff:ffff
145ff01:2090::/32ff01:2090:ffff:ffff:ffff:ffff:ffff:ffff
146ff01:2091::/32ff01:2091:ffff:ffff:ffff:ffff:ffff:ffff
147ff01:2092::/32ff01:2092:ffff:ffff:ffff:ffff:ffff:ffff
148ff01:2093::/32ff01:2093:ffff:ffff:ffff:ffff:ffff:ffff
149ff01:2094::/32ff01:2094:ffff:ffff:ffff:ffff:ffff:ffff
150ff01:2095::/32ff01:2095:ffff:ffff:ffff:ffff:ffff:ffff
151ff01:2096::/32ff01:2096:ffff:ffff:ffff:ffff:ffff:ffff
152ff01:2097::/32ff01:2097:ffff:ffff:ffff:ffff:ffff:ffff
153ff01:2098::/32ff01:2098:ffff:ffff:ffff:ffff:ffff:ffff
154ff01:2099::/32ff01:2099:ffff:ffff:ffff:ffff:ffff:ffff
155ff01:209a::/32ff01:209a:ffff:ffff:ffff:ffff:ffff:ffff
156ff01:209b::/32ff01:209b:ffff:ffff:ffff:ffff:ffff:ffff
157ff01:209c::/32ff01:209c:ffff:ffff:ffff:ffff:ffff:ffff
158ff01:209d::/32ff01:209d:ffff:ffff:ffff:ffff:ffff:ffff
159ff01:209e::/32ff01:209e:ffff:ffff:ffff:ffff:ffff:ffff
160ff01:209f::/32ff01:209f:ffff:ffff:ffff:ffff:ffff:ffff
161ff01:20a0::/32ff01:20a0:ffff:ffff:ffff:ffff:ffff:ffff
162ff01:20a1::/32ff01:20a1:ffff:ffff:ffff:ffff:ffff:ffff
163ff01:20a2::/32ff01:20a2:ffff:ffff:ffff:ffff:ffff:ffff
164ff01:20a3::/32ff01:20a3:ffff:ffff:ffff:ffff:ffff:ffff
165ff01:20a4::/32ff01:20a4:ffff:ffff:ffff:ffff:ffff:ffff
166ff01:20a5::/32ff01:20a5:ffff:ffff:ffff:ffff:ffff:ffff
167ff01:20a6::/32ff01:20a6:ffff:ffff:ffff:ffff:ffff:ffff
168ff01:20a7::/32ff01:20a7:ffff:ffff:ffff:ffff:ffff:ffff
169ff01:20a8::/32ff01:20a8:ffff:ffff:ffff:ffff:ffff:ffff
170ff01:20a9::/32ff01:20a9:ffff:ffff:ffff:ffff:ffff:ffff
171ff01:20aa::/32ff01:20aa:ffff:ffff:ffff:ffff:ffff:ffff
172ff01:20ab::/32ff01:20ab:ffff:ffff:ffff:ffff:ffff:ffff
173ff01:20ac::/32ff01:20ac:ffff:ffff:ffff:ffff:ffff:ffff
174ff01:20ad::/32ff01:20ad:ffff:ffff:ffff:ffff:ffff:ffff
175ff01:20ae::/32ff01:20ae:ffff:ffff:ffff:ffff:ffff:ffff
176ff01:20af::/32ff01:20af:ffff:ffff:ffff:ffff:ffff:ffff
177ff01:20b0::/32ff01:20b0:ffff:ffff:ffff:ffff:ffff:ffff
178ff01:20b1::/32ff01:20b1:ffff:ffff:ffff:ffff:ffff:ffff
179ff01:20b2::/32ff01:20b2:ffff:ffff:ffff:ffff:ffff:ffff
180ff01:20b3::/32ff01:20b3:ffff:ffff:ffff:ffff:ffff:ffff
181ff01:20b4::/32ff01:20b4:ffff:ffff:ffff:ffff:ffff:ffff
182ff01:20b5::/32ff01:20b5:ffff:ffff:ffff:ffff:ffff:ffff
183ff01:20b6::/32ff01:20b6:ffff:ffff:ffff:ffff:ffff:ffff
184ff01:20b7::/32ff01:20b7:ffff:ffff:ffff:ffff:ffff:ffff
185ff01:20b8::/32ff01:20b8:ffff:ffff:ffff:ffff:ffff:ffff
186ff01:20b9::/32ff01:20b9:ffff:ffff:ffff:ffff:ffff:ffff
187ff01:20ba::/32ff01:20ba:ffff:ffff:ffff:ffff:ffff:ffff
188ff01:20bb::/32ff01:20bb:ffff:ffff:ffff:ffff:ffff:ffff
189ff01:20bc::/32ff01:20bc:ffff:ffff:ffff:ffff:ffff:ffff
190ff01:20bd::/32ff01:20bd:ffff:ffff:ffff:ffff:ffff:ffff
191ff01:20be::/32ff01:20be:ffff:ffff:ffff:ffff:ffff:ffff
192ff01:20bf::/32ff01:20bf:ffff:ffff:ffff:ffff:ffff:ffff
193ff01:20c0::/32ff01:20c0:ffff:ffff:ffff:ffff:ffff:ffff
194ff01:20c1::/32ff01:20c1:ffff:ffff:ffff:ffff:ffff:ffff
195ff01:20c2::/32ff01:20c2:ffff:ffff:ffff:ffff:ffff:ffff
196ff01:20c3::/32ff01:20c3:ffff:ffff:ffff:ffff:ffff:ffff
197ff01:20c4::/32ff01:20c4:ffff:ffff:ffff:ffff:ffff:ffff
198ff01:20c5::/32ff01:20c5:ffff:ffff:ffff:ffff:ffff:ffff
199ff01:20c6::/32ff01:20c6:ffff:ffff:ffff:ffff:ffff:ffff
200ff01:20c7::/32ff01:20c7:ffff:ffff:ffff:ffff:ffff:ffff
201ff01:20c8::/32ff01:20c8:ffff:ffff:ffff:ffff:ffff:ffff
202ff01:20c9::/32ff01:20c9:ffff:ffff:ffff:ffff:ffff:ffff
203ff01:20ca::/32ff01:20ca:ffff:ffff:ffff:ffff:ffff:ffff
204ff01:20cb::/32ff01:20cb:ffff:ffff:ffff:ffff:ffff:ffff
205ff01:20cc::/32ff01:20cc:ffff:ffff:ffff:ffff:ffff:ffff
206ff01:20cd::/32ff01:20cd:ffff:ffff:ffff:ffff:ffff:ffff
207ff01:20ce::/32ff01:20ce:ffff:ffff:ffff:ffff:ffff:ffff
208ff01:20cf::/32ff01:20cf:ffff:ffff:ffff:ffff:ffff:ffff
209ff01:20d0::/32ff01:20d0:ffff:ffff:ffff:ffff:ffff:ffff
210ff01:20d1::/32ff01:20d1:ffff:ffff:ffff:ffff:ffff:ffff
211ff01:20d2::/32ff01:20d2:ffff:ffff:ffff:ffff:ffff:ffff
212ff01:20d3::/32ff01:20d3:ffff:ffff:ffff:ffff:ffff:ffff
213ff01:20d4::/32ff01:20d4:ffff:ffff:ffff:ffff:ffff:ffff
214ff01:20d5::/32ff01:20d5:ffff:ffff:ffff:ffff:ffff:ffff
215ff01:20d6::/32ff01:20d6:ffff:ffff:ffff:ffff:ffff:ffff
216ff01:20d7::/32ff01:20d7:ffff:ffff:ffff:ffff:ffff:ffff
217ff01:20d8::/32ff01:20d8:ffff:ffff:ffff:ffff:ffff:ffff
218ff01:20d9::/32ff01:20d9:ffff:ffff:ffff:ffff:ffff:ffff
219ff01:20da::/32ff01:20da:ffff:ffff:ffff:ffff:ffff:ffff
220ff01:20db::/32ff01:20db:ffff:ffff:ffff:ffff:ffff:ffff
221ff01:20dc::/32ff01:20dc:ffff:ffff:ffff:ffff:ffff:ffff
222ff01:20dd::/32ff01:20dd:ffff:ffff:ffff:ffff:ffff:ffff
223ff01:20de::/32ff01:20de:ffff:ffff:ffff:ffff:ffff:ffff
224ff01:20df::/32ff01:20df:ffff:ffff:ffff:ffff:ffff:ffff
225ff01:20e0::/32ff01:20e0:ffff:ffff:ffff:ffff:ffff:ffff
226ff01:20e1::/32ff01:20e1:ffff:ffff:ffff:ffff:ffff:ffff
227ff01:20e2::/32ff01:20e2:ffff:ffff:ffff:ffff:ffff:ffff
228ff01:20e3::/32ff01:20e3:ffff:ffff:ffff:ffff:ffff:ffff
229ff01:20e4::/32ff01:20e4:ffff:ffff:ffff:ffff:ffff:ffff
230ff01:20e5::/32ff01:20e5:ffff:ffff:ffff:ffff:ffff:ffff
231ff01:20e6::/32ff01:20e6:ffff:ffff:ffff:ffff:ffff:ffff
232ff01:20e7::/32ff01:20e7:ffff:ffff:ffff:ffff:ffff:ffff
233ff01:20e8::/32ff01:20e8:ffff:ffff:ffff:ffff:ffff:ffff
234ff01:20e9::/32ff01:20e9:ffff:ffff:ffff:ffff:ffff:ffff
235ff01:20ea::/32ff01:20ea:ffff:ffff:ffff:ffff:ffff:ffff
236ff01:20eb::/32ff01:20eb:ffff:ffff:ffff:ffff:ffff:ffff
237ff01:20ec::/32ff01:20ec:ffff:ffff:ffff:ffff:ffff:ffff
238ff01:20ed::/32ff01:20ed:ffff:ffff:ffff:ffff:ffff:ffff
239ff01:20ee::/32ff01:20ee:ffff:ffff:ffff:ffff:ffff:ffff
240ff01:20ef::/32ff01:20ef:ffff:ffff:ffff:ffff:ffff:ffff
241ff01:20f0::/32ff01:20f0:ffff:ffff:ffff:ffff:ffff:ffff
242ff01:20f1::/32ff01:20f1:ffff:ffff:ffff:ffff:ffff:ffff
243ff01:20f2::/32ff01:20f2:ffff:ffff:ffff:ffff:ffff:ffff
244ff01:20f3::/32ff01:20f3:ffff:ffff:ffff:ffff:ffff:ffff
245ff01:20f4::/32ff01:20f4:ffff:ffff:ffff:ffff:ffff:ffff
246ff01:20f5::/32ff01:20f5:ffff:ffff:ffff:ffff:ffff:ffff
247ff01:20f6::/32ff01:20f6:ffff:ffff:ffff:ffff:ffff:ffff
248ff01:20f7::/32ff01:20f7:ffff:ffff:ffff:ffff:ffff:ffff
249ff01:20f8::/32ff01:20f8:ffff:ffff:ffff:ffff:ffff:ffff
250ff01:20f9::/32ff01:20f9:ffff:ffff:ffff:ffff:ffff:ffff
251ff01:20fa::/32ff01:20fa:ffff:ffff:ffff:ffff:ffff:ffff
252ff01:20fb::/32ff01:20fb:ffff:ffff:ffff:ffff:ffff:ffff
253ff01:20fc::/32ff01:20fc:ffff:ffff:ffff:ffff:ffff:ffff
254ff01:20fd::/32ff01:20fd:ffff:ffff:ffff:ffff:ffff:ffff
255ff01:20fe::/32ff01:20fe:ffff:ffff:ffff:ffff:ffff:ffff
256ff01:20ff::/32ff01:20ff: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.