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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
ff0c:2000::/20
First address
ff0c:2000::
Last address
ff0c: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
ff0c:2000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
2.c.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)

ff0c:2000::/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1ff0c:2000::/32ff0c:2000:ffff:ffff:ffff:ffff:ffff:ffff
2ff0c:2001::/32ff0c:2001:ffff:ffff:ffff:ffff:ffff:ffff
3ff0c:2002::/32ff0c:2002:ffff:ffff:ffff:ffff:ffff:ffff
4ff0c:2003::/32ff0c:2003:ffff:ffff:ffff:ffff:ffff:ffff
5ff0c:2004::/32ff0c:2004:ffff:ffff:ffff:ffff:ffff:ffff
6ff0c:2005::/32ff0c:2005:ffff:ffff:ffff:ffff:ffff:ffff
7ff0c:2006::/32ff0c:2006:ffff:ffff:ffff:ffff:ffff:ffff
8ff0c:2007::/32ff0c:2007:ffff:ffff:ffff:ffff:ffff:ffff
9ff0c:2008::/32ff0c:2008:ffff:ffff:ffff:ffff:ffff:ffff
10ff0c:2009::/32ff0c:2009:ffff:ffff:ffff:ffff:ffff:ffff
11ff0c:200a::/32ff0c:200a:ffff:ffff:ffff:ffff:ffff:ffff
12ff0c:200b::/32ff0c:200b:ffff:ffff:ffff:ffff:ffff:ffff
13ff0c:200c::/32ff0c:200c:ffff:ffff:ffff:ffff:ffff:ffff
14ff0c:200d::/32ff0c:200d:ffff:ffff:ffff:ffff:ffff:ffff
15ff0c:200e::/32ff0c:200e:ffff:ffff:ffff:ffff:ffff:ffff
16ff0c:200f::/32ff0c:200f:ffff:ffff:ffff:ffff:ffff:ffff
17ff0c:2010::/32ff0c:2010:ffff:ffff:ffff:ffff:ffff:ffff
18ff0c:2011::/32ff0c:2011:ffff:ffff:ffff:ffff:ffff:ffff
19ff0c:2012::/32ff0c:2012:ffff:ffff:ffff:ffff:ffff:ffff
20ff0c:2013::/32ff0c:2013:ffff:ffff:ffff:ffff:ffff:ffff
21ff0c:2014::/32ff0c:2014:ffff:ffff:ffff:ffff:ffff:ffff
22ff0c:2015::/32ff0c:2015:ffff:ffff:ffff:ffff:ffff:ffff
23ff0c:2016::/32ff0c:2016:ffff:ffff:ffff:ffff:ffff:ffff
24ff0c:2017::/32ff0c:2017:ffff:ffff:ffff:ffff:ffff:ffff
25ff0c:2018::/32ff0c:2018:ffff:ffff:ffff:ffff:ffff:ffff
26ff0c:2019::/32ff0c:2019:ffff:ffff:ffff:ffff:ffff:ffff
27ff0c:201a::/32ff0c:201a:ffff:ffff:ffff:ffff:ffff:ffff
28ff0c:201b::/32ff0c:201b:ffff:ffff:ffff:ffff:ffff:ffff
29ff0c:201c::/32ff0c:201c:ffff:ffff:ffff:ffff:ffff:ffff
30ff0c:201d::/32ff0c:201d:ffff:ffff:ffff:ffff:ffff:ffff
31ff0c:201e::/32ff0c:201e:ffff:ffff:ffff:ffff:ffff:ffff
32ff0c:201f::/32ff0c:201f:ffff:ffff:ffff:ffff:ffff:ffff
33ff0c:2020::/32ff0c:2020:ffff:ffff:ffff:ffff:ffff:ffff
34ff0c:2021::/32ff0c:2021:ffff:ffff:ffff:ffff:ffff:ffff
35ff0c:2022::/32ff0c:2022:ffff:ffff:ffff:ffff:ffff:ffff
36ff0c:2023::/32ff0c:2023:ffff:ffff:ffff:ffff:ffff:ffff
37ff0c:2024::/32ff0c:2024:ffff:ffff:ffff:ffff:ffff:ffff
38ff0c:2025::/32ff0c:2025:ffff:ffff:ffff:ffff:ffff:ffff
39ff0c:2026::/32ff0c:2026:ffff:ffff:ffff:ffff:ffff:ffff
40ff0c:2027::/32ff0c:2027:ffff:ffff:ffff:ffff:ffff:ffff
41ff0c:2028::/32ff0c:2028:ffff:ffff:ffff:ffff:ffff:ffff
42ff0c:2029::/32ff0c:2029:ffff:ffff:ffff:ffff:ffff:ffff
43ff0c:202a::/32ff0c:202a:ffff:ffff:ffff:ffff:ffff:ffff
44ff0c:202b::/32ff0c:202b:ffff:ffff:ffff:ffff:ffff:ffff
45ff0c:202c::/32ff0c:202c:ffff:ffff:ffff:ffff:ffff:ffff
46ff0c:202d::/32ff0c:202d:ffff:ffff:ffff:ffff:ffff:ffff
47ff0c:202e::/32ff0c:202e:ffff:ffff:ffff:ffff:ffff:ffff
48ff0c:202f::/32ff0c:202f:ffff:ffff:ffff:ffff:ffff:ffff
49ff0c:2030::/32ff0c:2030:ffff:ffff:ffff:ffff:ffff:ffff
50ff0c:2031::/32ff0c:2031:ffff:ffff:ffff:ffff:ffff:ffff
51ff0c:2032::/32ff0c:2032:ffff:ffff:ffff:ffff:ffff:ffff
52ff0c:2033::/32ff0c:2033:ffff:ffff:ffff:ffff:ffff:ffff
53ff0c:2034::/32ff0c:2034:ffff:ffff:ffff:ffff:ffff:ffff
54ff0c:2035::/32ff0c:2035:ffff:ffff:ffff:ffff:ffff:ffff
55ff0c:2036::/32ff0c:2036:ffff:ffff:ffff:ffff:ffff:ffff
56ff0c:2037::/32ff0c:2037:ffff:ffff:ffff:ffff:ffff:ffff
57ff0c:2038::/32ff0c:2038:ffff:ffff:ffff:ffff:ffff:ffff
58ff0c:2039::/32ff0c:2039:ffff:ffff:ffff:ffff:ffff:ffff
59ff0c:203a::/32ff0c:203a:ffff:ffff:ffff:ffff:ffff:ffff
60ff0c:203b::/32ff0c:203b:ffff:ffff:ffff:ffff:ffff:ffff
61ff0c:203c::/32ff0c:203c:ffff:ffff:ffff:ffff:ffff:ffff
62ff0c:203d::/32ff0c:203d:ffff:ffff:ffff:ffff:ffff:ffff
63ff0c:203e::/32ff0c:203e:ffff:ffff:ffff:ffff:ffff:ffff
64ff0c:203f::/32ff0c:203f:ffff:ffff:ffff:ffff:ffff:ffff
65ff0c:2040::/32ff0c:2040:ffff:ffff:ffff:ffff:ffff:ffff
66ff0c:2041::/32ff0c:2041:ffff:ffff:ffff:ffff:ffff:ffff
67ff0c:2042::/32ff0c:2042:ffff:ffff:ffff:ffff:ffff:ffff
68ff0c:2043::/32ff0c:2043:ffff:ffff:ffff:ffff:ffff:ffff
69ff0c:2044::/32ff0c:2044:ffff:ffff:ffff:ffff:ffff:ffff
70ff0c:2045::/32ff0c:2045:ffff:ffff:ffff:ffff:ffff:ffff
71ff0c:2046::/32ff0c:2046:ffff:ffff:ffff:ffff:ffff:ffff
72ff0c:2047::/32ff0c:2047:ffff:ffff:ffff:ffff:ffff:ffff
73ff0c:2048::/32ff0c:2048:ffff:ffff:ffff:ffff:ffff:ffff
74ff0c:2049::/32ff0c:2049:ffff:ffff:ffff:ffff:ffff:ffff
75ff0c:204a::/32ff0c:204a:ffff:ffff:ffff:ffff:ffff:ffff
76ff0c:204b::/32ff0c:204b:ffff:ffff:ffff:ffff:ffff:ffff
77ff0c:204c::/32ff0c:204c:ffff:ffff:ffff:ffff:ffff:ffff
78ff0c:204d::/32ff0c:204d:ffff:ffff:ffff:ffff:ffff:ffff
79ff0c:204e::/32ff0c:204e:ffff:ffff:ffff:ffff:ffff:ffff
80ff0c:204f::/32ff0c:204f:ffff:ffff:ffff:ffff:ffff:ffff
81ff0c:2050::/32ff0c:2050:ffff:ffff:ffff:ffff:ffff:ffff
82ff0c:2051::/32ff0c:2051:ffff:ffff:ffff:ffff:ffff:ffff
83ff0c:2052::/32ff0c:2052:ffff:ffff:ffff:ffff:ffff:ffff
84ff0c:2053::/32ff0c:2053:ffff:ffff:ffff:ffff:ffff:ffff
85ff0c:2054::/32ff0c:2054:ffff:ffff:ffff:ffff:ffff:ffff
86ff0c:2055::/32ff0c:2055:ffff:ffff:ffff:ffff:ffff:ffff
87ff0c:2056::/32ff0c:2056:ffff:ffff:ffff:ffff:ffff:ffff
88ff0c:2057::/32ff0c:2057:ffff:ffff:ffff:ffff:ffff:ffff
89ff0c:2058::/32ff0c:2058:ffff:ffff:ffff:ffff:ffff:ffff
90ff0c:2059::/32ff0c:2059:ffff:ffff:ffff:ffff:ffff:ffff
91ff0c:205a::/32ff0c:205a:ffff:ffff:ffff:ffff:ffff:ffff
92ff0c:205b::/32ff0c:205b:ffff:ffff:ffff:ffff:ffff:ffff
93ff0c:205c::/32ff0c:205c:ffff:ffff:ffff:ffff:ffff:ffff
94ff0c:205d::/32ff0c:205d:ffff:ffff:ffff:ffff:ffff:ffff
95ff0c:205e::/32ff0c:205e:ffff:ffff:ffff:ffff:ffff:ffff
96ff0c:205f::/32ff0c:205f:ffff:ffff:ffff:ffff:ffff:ffff
97ff0c:2060::/32ff0c:2060:ffff:ffff:ffff:ffff:ffff:ffff
98ff0c:2061::/32ff0c:2061:ffff:ffff:ffff:ffff:ffff:ffff
99ff0c:2062::/32ff0c:2062:ffff:ffff:ffff:ffff:ffff:ffff
100ff0c:2063::/32ff0c:2063:ffff:ffff:ffff:ffff:ffff:ffff
101ff0c:2064::/32ff0c:2064:ffff:ffff:ffff:ffff:ffff:ffff
102ff0c:2065::/32ff0c:2065:ffff:ffff:ffff:ffff:ffff:ffff
103ff0c:2066::/32ff0c:2066:ffff:ffff:ffff:ffff:ffff:ffff
104ff0c:2067::/32ff0c:2067:ffff:ffff:ffff:ffff:ffff:ffff
105ff0c:2068::/32ff0c:2068:ffff:ffff:ffff:ffff:ffff:ffff
106ff0c:2069::/32ff0c:2069:ffff:ffff:ffff:ffff:ffff:ffff
107ff0c:206a::/32ff0c:206a:ffff:ffff:ffff:ffff:ffff:ffff
108ff0c:206b::/32ff0c:206b:ffff:ffff:ffff:ffff:ffff:ffff
109ff0c:206c::/32ff0c:206c:ffff:ffff:ffff:ffff:ffff:ffff
110ff0c:206d::/32ff0c:206d:ffff:ffff:ffff:ffff:ffff:ffff
111ff0c:206e::/32ff0c:206e:ffff:ffff:ffff:ffff:ffff:ffff
112ff0c:206f::/32ff0c:206f:ffff:ffff:ffff:ffff:ffff:ffff
113ff0c:2070::/32ff0c:2070:ffff:ffff:ffff:ffff:ffff:ffff
114ff0c:2071::/32ff0c:2071:ffff:ffff:ffff:ffff:ffff:ffff
115ff0c:2072::/32ff0c:2072:ffff:ffff:ffff:ffff:ffff:ffff
116ff0c:2073::/32ff0c:2073:ffff:ffff:ffff:ffff:ffff:ffff
117ff0c:2074::/32ff0c:2074:ffff:ffff:ffff:ffff:ffff:ffff
118ff0c:2075::/32ff0c:2075:ffff:ffff:ffff:ffff:ffff:ffff
119ff0c:2076::/32ff0c:2076:ffff:ffff:ffff:ffff:ffff:ffff
120ff0c:2077::/32ff0c:2077:ffff:ffff:ffff:ffff:ffff:ffff
121ff0c:2078::/32ff0c:2078:ffff:ffff:ffff:ffff:ffff:ffff
122ff0c:2079::/32ff0c:2079:ffff:ffff:ffff:ffff:ffff:ffff
123ff0c:207a::/32ff0c:207a:ffff:ffff:ffff:ffff:ffff:ffff
124ff0c:207b::/32ff0c:207b:ffff:ffff:ffff:ffff:ffff:ffff
125ff0c:207c::/32ff0c:207c:ffff:ffff:ffff:ffff:ffff:ffff
126ff0c:207d::/32ff0c:207d:ffff:ffff:ffff:ffff:ffff:ffff
127ff0c:207e::/32ff0c:207e:ffff:ffff:ffff:ffff:ffff:ffff
128ff0c:207f::/32ff0c:207f:ffff:ffff:ffff:ffff:ffff:ffff
129ff0c:2080::/32ff0c:2080:ffff:ffff:ffff:ffff:ffff:ffff
130ff0c:2081::/32ff0c:2081:ffff:ffff:ffff:ffff:ffff:ffff
131ff0c:2082::/32ff0c:2082:ffff:ffff:ffff:ffff:ffff:ffff
132ff0c:2083::/32ff0c:2083:ffff:ffff:ffff:ffff:ffff:ffff
133ff0c:2084::/32ff0c:2084:ffff:ffff:ffff:ffff:ffff:ffff
134ff0c:2085::/32ff0c:2085:ffff:ffff:ffff:ffff:ffff:ffff
135ff0c:2086::/32ff0c:2086:ffff:ffff:ffff:ffff:ffff:ffff
136ff0c:2087::/32ff0c:2087:ffff:ffff:ffff:ffff:ffff:ffff
137ff0c:2088::/32ff0c:2088:ffff:ffff:ffff:ffff:ffff:ffff
138ff0c:2089::/32ff0c:2089:ffff:ffff:ffff:ffff:ffff:ffff
139ff0c:208a::/32ff0c:208a:ffff:ffff:ffff:ffff:ffff:ffff
140ff0c:208b::/32ff0c:208b:ffff:ffff:ffff:ffff:ffff:ffff
141ff0c:208c::/32ff0c:208c:ffff:ffff:ffff:ffff:ffff:ffff
142ff0c:208d::/32ff0c:208d:ffff:ffff:ffff:ffff:ffff:ffff
143ff0c:208e::/32ff0c:208e:ffff:ffff:ffff:ffff:ffff:ffff
144ff0c:208f::/32ff0c:208f:ffff:ffff:ffff:ffff:ffff:ffff
145ff0c:2090::/32ff0c:2090:ffff:ffff:ffff:ffff:ffff:ffff
146ff0c:2091::/32ff0c:2091:ffff:ffff:ffff:ffff:ffff:ffff
147ff0c:2092::/32ff0c:2092:ffff:ffff:ffff:ffff:ffff:ffff
148ff0c:2093::/32ff0c:2093:ffff:ffff:ffff:ffff:ffff:ffff
149ff0c:2094::/32ff0c:2094:ffff:ffff:ffff:ffff:ffff:ffff
150ff0c:2095::/32ff0c:2095:ffff:ffff:ffff:ffff:ffff:ffff
151ff0c:2096::/32ff0c:2096:ffff:ffff:ffff:ffff:ffff:ffff
152ff0c:2097::/32ff0c:2097:ffff:ffff:ffff:ffff:ffff:ffff
153ff0c:2098::/32ff0c:2098:ffff:ffff:ffff:ffff:ffff:ffff
154ff0c:2099::/32ff0c:2099:ffff:ffff:ffff:ffff:ffff:ffff
155ff0c:209a::/32ff0c:209a:ffff:ffff:ffff:ffff:ffff:ffff
156ff0c:209b::/32ff0c:209b:ffff:ffff:ffff:ffff:ffff:ffff
157ff0c:209c::/32ff0c:209c:ffff:ffff:ffff:ffff:ffff:ffff
158ff0c:209d::/32ff0c:209d:ffff:ffff:ffff:ffff:ffff:ffff
159ff0c:209e::/32ff0c:209e:ffff:ffff:ffff:ffff:ffff:ffff
160ff0c:209f::/32ff0c:209f:ffff:ffff:ffff:ffff:ffff:ffff
161ff0c:20a0::/32ff0c:20a0:ffff:ffff:ffff:ffff:ffff:ffff
162ff0c:20a1::/32ff0c:20a1:ffff:ffff:ffff:ffff:ffff:ffff
163ff0c:20a2::/32ff0c:20a2:ffff:ffff:ffff:ffff:ffff:ffff
164ff0c:20a3::/32ff0c:20a3:ffff:ffff:ffff:ffff:ffff:ffff
165ff0c:20a4::/32ff0c:20a4:ffff:ffff:ffff:ffff:ffff:ffff
166ff0c:20a5::/32ff0c:20a5:ffff:ffff:ffff:ffff:ffff:ffff
167ff0c:20a6::/32ff0c:20a6:ffff:ffff:ffff:ffff:ffff:ffff
168ff0c:20a7::/32ff0c:20a7:ffff:ffff:ffff:ffff:ffff:ffff
169ff0c:20a8::/32ff0c:20a8:ffff:ffff:ffff:ffff:ffff:ffff
170ff0c:20a9::/32ff0c:20a9:ffff:ffff:ffff:ffff:ffff:ffff
171ff0c:20aa::/32ff0c:20aa:ffff:ffff:ffff:ffff:ffff:ffff
172ff0c:20ab::/32ff0c:20ab:ffff:ffff:ffff:ffff:ffff:ffff
173ff0c:20ac::/32ff0c:20ac:ffff:ffff:ffff:ffff:ffff:ffff
174ff0c:20ad::/32ff0c:20ad:ffff:ffff:ffff:ffff:ffff:ffff
175ff0c:20ae::/32ff0c:20ae:ffff:ffff:ffff:ffff:ffff:ffff
176ff0c:20af::/32ff0c:20af:ffff:ffff:ffff:ffff:ffff:ffff
177ff0c:20b0::/32ff0c:20b0:ffff:ffff:ffff:ffff:ffff:ffff
178ff0c:20b1::/32ff0c:20b1:ffff:ffff:ffff:ffff:ffff:ffff
179ff0c:20b2::/32ff0c:20b2:ffff:ffff:ffff:ffff:ffff:ffff
180ff0c:20b3::/32ff0c:20b3:ffff:ffff:ffff:ffff:ffff:ffff
181ff0c:20b4::/32ff0c:20b4:ffff:ffff:ffff:ffff:ffff:ffff
182ff0c:20b5::/32ff0c:20b5:ffff:ffff:ffff:ffff:ffff:ffff
183ff0c:20b6::/32ff0c:20b6:ffff:ffff:ffff:ffff:ffff:ffff
184ff0c:20b7::/32ff0c:20b7:ffff:ffff:ffff:ffff:ffff:ffff
185ff0c:20b8::/32ff0c:20b8:ffff:ffff:ffff:ffff:ffff:ffff
186ff0c:20b9::/32ff0c:20b9:ffff:ffff:ffff:ffff:ffff:ffff
187ff0c:20ba::/32ff0c:20ba:ffff:ffff:ffff:ffff:ffff:ffff
188ff0c:20bb::/32ff0c:20bb:ffff:ffff:ffff:ffff:ffff:ffff
189ff0c:20bc::/32ff0c:20bc:ffff:ffff:ffff:ffff:ffff:ffff
190ff0c:20bd::/32ff0c:20bd:ffff:ffff:ffff:ffff:ffff:ffff
191ff0c:20be::/32ff0c:20be:ffff:ffff:ffff:ffff:ffff:ffff
192ff0c:20bf::/32ff0c:20bf:ffff:ffff:ffff:ffff:ffff:ffff
193ff0c:20c0::/32ff0c:20c0:ffff:ffff:ffff:ffff:ffff:ffff
194ff0c:20c1::/32ff0c:20c1:ffff:ffff:ffff:ffff:ffff:ffff
195ff0c:20c2::/32ff0c:20c2:ffff:ffff:ffff:ffff:ffff:ffff
196ff0c:20c3::/32ff0c:20c3:ffff:ffff:ffff:ffff:ffff:ffff
197ff0c:20c4::/32ff0c:20c4:ffff:ffff:ffff:ffff:ffff:ffff
198ff0c:20c5::/32ff0c:20c5:ffff:ffff:ffff:ffff:ffff:ffff
199ff0c:20c6::/32ff0c:20c6:ffff:ffff:ffff:ffff:ffff:ffff
200ff0c:20c7::/32ff0c:20c7:ffff:ffff:ffff:ffff:ffff:ffff
201ff0c:20c8::/32ff0c:20c8:ffff:ffff:ffff:ffff:ffff:ffff
202ff0c:20c9::/32ff0c:20c9:ffff:ffff:ffff:ffff:ffff:ffff
203ff0c:20ca::/32ff0c:20ca:ffff:ffff:ffff:ffff:ffff:ffff
204ff0c:20cb::/32ff0c:20cb:ffff:ffff:ffff:ffff:ffff:ffff
205ff0c:20cc::/32ff0c:20cc:ffff:ffff:ffff:ffff:ffff:ffff
206ff0c:20cd::/32ff0c:20cd:ffff:ffff:ffff:ffff:ffff:ffff
207ff0c:20ce::/32ff0c:20ce:ffff:ffff:ffff:ffff:ffff:ffff
208ff0c:20cf::/32ff0c:20cf:ffff:ffff:ffff:ffff:ffff:ffff
209ff0c:20d0::/32ff0c:20d0:ffff:ffff:ffff:ffff:ffff:ffff
210ff0c:20d1::/32ff0c:20d1:ffff:ffff:ffff:ffff:ffff:ffff
211ff0c:20d2::/32ff0c:20d2:ffff:ffff:ffff:ffff:ffff:ffff
212ff0c:20d3::/32ff0c:20d3:ffff:ffff:ffff:ffff:ffff:ffff
213ff0c:20d4::/32ff0c:20d4:ffff:ffff:ffff:ffff:ffff:ffff
214ff0c:20d5::/32ff0c:20d5:ffff:ffff:ffff:ffff:ffff:ffff
215ff0c:20d6::/32ff0c:20d6:ffff:ffff:ffff:ffff:ffff:ffff
216ff0c:20d7::/32ff0c:20d7:ffff:ffff:ffff:ffff:ffff:ffff
217ff0c:20d8::/32ff0c:20d8:ffff:ffff:ffff:ffff:ffff:ffff
218ff0c:20d9::/32ff0c:20d9:ffff:ffff:ffff:ffff:ffff:ffff
219ff0c:20da::/32ff0c:20da:ffff:ffff:ffff:ffff:ffff:ffff
220ff0c:20db::/32ff0c:20db:ffff:ffff:ffff:ffff:ffff:ffff
221ff0c:20dc::/32ff0c:20dc:ffff:ffff:ffff:ffff:ffff:ffff
222ff0c:20dd::/32ff0c:20dd:ffff:ffff:ffff:ffff:ffff:ffff
223ff0c:20de::/32ff0c:20de:ffff:ffff:ffff:ffff:ffff:ffff
224ff0c:20df::/32ff0c:20df:ffff:ffff:ffff:ffff:ffff:ffff
225ff0c:20e0::/32ff0c:20e0:ffff:ffff:ffff:ffff:ffff:ffff
226ff0c:20e1::/32ff0c:20e1:ffff:ffff:ffff:ffff:ffff:ffff
227ff0c:20e2::/32ff0c:20e2:ffff:ffff:ffff:ffff:ffff:ffff
228ff0c:20e3::/32ff0c:20e3:ffff:ffff:ffff:ffff:ffff:ffff
229ff0c:20e4::/32ff0c:20e4:ffff:ffff:ffff:ffff:ffff:ffff
230ff0c:20e5::/32ff0c:20e5:ffff:ffff:ffff:ffff:ffff:ffff
231ff0c:20e6::/32ff0c:20e6:ffff:ffff:ffff:ffff:ffff:ffff
232ff0c:20e7::/32ff0c:20e7:ffff:ffff:ffff:ffff:ffff:ffff
233ff0c:20e8::/32ff0c:20e8:ffff:ffff:ffff:ffff:ffff:ffff
234ff0c:20e9::/32ff0c:20e9:ffff:ffff:ffff:ffff:ffff:ffff
235ff0c:20ea::/32ff0c:20ea:ffff:ffff:ffff:ffff:ffff:ffff
236ff0c:20eb::/32ff0c:20eb:ffff:ffff:ffff:ffff:ffff:ffff
237ff0c:20ec::/32ff0c:20ec:ffff:ffff:ffff:ffff:ffff:ffff
238ff0c:20ed::/32ff0c:20ed:ffff:ffff:ffff:ffff:ffff:ffff
239ff0c:20ee::/32ff0c:20ee:ffff:ffff:ffff:ffff:ffff:ffff
240ff0c:20ef::/32ff0c:20ef:ffff:ffff:ffff:ffff:ffff:ffff
241ff0c:20f0::/32ff0c:20f0:ffff:ffff:ffff:ffff:ffff:ffff
242ff0c:20f1::/32ff0c:20f1:ffff:ffff:ffff:ffff:ffff:ffff
243ff0c:20f2::/32ff0c:20f2:ffff:ffff:ffff:ffff:ffff:ffff
244ff0c:20f3::/32ff0c:20f3:ffff:ffff:ffff:ffff:ffff:ffff
245ff0c:20f4::/32ff0c:20f4:ffff:ffff:ffff:ffff:ffff:ffff
246ff0c:20f5::/32ff0c:20f5:ffff:ffff:ffff:ffff:ffff:ffff
247ff0c:20f6::/32ff0c:20f6:ffff:ffff:ffff:ffff:ffff:ffff
248ff0c:20f7::/32ff0c:20f7:ffff:ffff:ffff:ffff:ffff:ffff
249ff0c:20f8::/32ff0c:20f8:ffff:ffff:ffff:ffff:ffff:ffff
250ff0c:20f9::/32ff0c:20f9:ffff:ffff:ffff:ffff:ffff:ffff
251ff0c:20fa::/32ff0c:20fa:ffff:ffff:ffff:ffff:ffff:ffff
252ff0c:20fb::/32ff0c:20fb:ffff:ffff:ffff:ffff:ffff:ffff
253ff0c:20fc::/32ff0c:20fc:ffff:ffff:ffff:ffff:ffff:ffff
254ff0c:20fd::/32ff0c:20fd:ffff:ffff:ffff:ffff:ffff:ffff
255ff0c:20fe::/32ff0c:20fe:ffff:ffff:ffff:ffff:ffff:ffff
256ff0c:20ff::/32ff0c: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.