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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
fc05:2000::/20
First address
fc05:2000::
Last address
fc05:2fff: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
fc05:2000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
2.5.0.c.f.ip6.arpa
Split into smaller subnets/32
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

fc05:2000::/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1fc05:2000::/32fc05:2000:ffff:ffff:ffff:ffff:ffff:ffff
2fc05:2001::/32fc05:2001:ffff:ffff:ffff:ffff:ffff:ffff
3fc05:2002::/32fc05:2002:ffff:ffff:ffff:ffff:ffff:ffff
4fc05:2003::/32fc05:2003:ffff:ffff:ffff:ffff:ffff:ffff
5fc05:2004::/32fc05:2004:ffff:ffff:ffff:ffff:ffff:ffff
6fc05:2005::/32fc05:2005:ffff:ffff:ffff:ffff:ffff:ffff
7fc05:2006::/32fc05:2006:ffff:ffff:ffff:ffff:ffff:ffff
8fc05:2007::/32fc05:2007:ffff:ffff:ffff:ffff:ffff:ffff
9fc05:2008::/32fc05:2008:ffff:ffff:ffff:ffff:ffff:ffff
10fc05:2009::/32fc05:2009:ffff:ffff:ffff:ffff:ffff:ffff
11fc05:200a::/32fc05:200a:ffff:ffff:ffff:ffff:ffff:ffff
12fc05:200b::/32fc05:200b:ffff:ffff:ffff:ffff:ffff:ffff
13fc05:200c::/32fc05:200c:ffff:ffff:ffff:ffff:ffff:ffff
14fc05:200d::/32fc05:200d:ffff:ffff:ffff:ffff:ffff:ffff
15fc05:200e::/32fc05:200e:ffff:ffff:ffff:ffff:ffff:ffff
16fc05:200f::/32fc05:200f:ffff:ffff:ffff:ffff:ffff:ffff
17fc05:2010::/32fc05:2010:ffff:ffff:ffff:ffff:ffff:ffff
18fc05:2011::/32fc05:2011:ffff:ffff:ffff:ffff:ffff:ffff
19fc05:2012::/32fc05:2012:ffff:ffff:ffff:ffff:ffff:ffff
20fc05:2013::/32fc05:2013:ffff:ffff:ffff:ffff:ffff:ffff
21fc05:2014::/32fc05:2014:ffff:ffff:ffff:ffff:ffff:ffff
22fc05:2015::/32fc05:2015:ffff:ffff:ffff:ffff:ffff:ffff
23fc05:2016::/32fc05:2016:ffff:ffff:ffff:ffff:ffff:ffff
24fc05:2017::/32fc05:2017:ffff:ffff:ffff:ffff:ffff:ffff
25fc05:2018::/32fc05:2018:ffff:ffff:ffff:ffff:ffff:ffff
26fc05:2019::/32fc05:2019:ffff:ffff:ffff:ffff:ffff:ffff
27fc05:201a::/32fc05:201a:ffff:ffff:ffff:ffff:ffff:ffff
28fc05:201b::/32fc05:201b:ffff:ffff:ffff:ffff:ffff:ffff
29fc05:201c::/32fc05:201c:ffff:ffff:ffff:ffff:ffff:ffff
30fc05:201d::/32fc05:201d:ffff:ffff:ffff:ffff:ffff:ffff
31fc05:201e::/32fc05:201e:ffff:ffff:ffff:ffff:ffff:ffff
32fc05:201f::/32fc05:201f:ffff:ffff:ffff:ffff:ffff:ffff
33fc05:2020::/32fc05:2020:ffff:ffff:ffff:ffff:ffff:ffff
34fc05:2021::/32fc05:2021:ffff:ffff:ffff:ffff:ffff:ffff
35fc05:2022::/32fc05:2022:ffff:ffff:ffff:ffff:ffff:ffff
36fc05:2023::/32fc05:2023:ffff:ffff:ffff:ffff:ffff:ffff
37fc05:2024::/32fc05:2024:ffff:ffff:ffff:ffff:ffff:ffff
38fc05:2025::/32fc05:2025:ffff:ffff:ffff:ffff:ffff:ffff
39fc05:2026::/32fc05:2026:ffff:ffff:ffff:ffff:ffff:ffff
40fc05:2027::/32fc05:2027:ffff:ffff:ffff:ffff:ffff:ffff
41fc05:2028::/32fc05:2028:ffff:ffff:ffff:ffff:ffff:ffff
42fc05:2029::/32fc05:2029:ffff:ffff:ffff:ffff:ffff:ffff
43fc05:202a::/32fc05:202a:ffff:ffff:ffff:ffff:ffff:ffff
44fc05:202b::/32fc05:202b:ffff:ffff:ffff:ffff:ffff:ffff
45fc05:202c::/32fc05:202c:ffff:ffff:ffff:ffff:ffff:ffff
46fc05:202d::/32fc05:202d:ffff:ffff:ffff:ffff:ffff:ffff
47fc05:202e::/32fc05:202e:ffff:ffff:ffff:ffff:ffff:ffff
48fc05:202f::/32fc05:202f:ffff:ffff:ffff:ffff:ffff:ffff
49fc05:2030::/32fc05:2030:ffff:ffff:ffff:ffff:ffff:ffff
50fc05:2031::/32fc05:2031:ffff:ffff:ffff:ffff:ffff:ffff
51fc05:2032::/32fc05:2032:ffff:ffff:ffff:ffff:ffff:ffff
52fc05:2033::/32fc05:2033:ffff:ffff:ffff:ffff:ffff:ffff
53fc05:2034::/32fc05:2034:ffff:ffff:ffff:ffff:ffff:ffff
54fc05:2035::/32fc05:2035:ffff:ffff:ffff:ffff:ffff:ffff
55fc05:2036::/32fc05:2036:ffff:ffff:ffff:ffff:ffff:ffff
56fc05:2037::/32fc05:2037:ffff:ffff:ffff:ffff:ffff:ffff
57fc05:2038::/32fc05:2038:ffff:ffff:ffff:ffff:ffff:ffff
58fc05:2039::/32fc05:2039:ffff:ffff:ffff:ffff:ffff:ffff
59fc05:203a::/32fc05:203a:ffff:ffff:ffff:ffff:ffff:ffff
60fc05:203b::/32fc05:203b:ffff:ffff:ffff:ffff:ffff:ffff
61fc05:203c::/32fc05:203c:ffff:ffff:ffff:ffff:ffff:ffff
62fc05:203d::/32fc05:203d:ffff:ffff:ffff:ffff:ffff:ffff
63fc05:203e::/32fc05:203e:ffff:ffff:ffff:ffff:ffff:ffff
64fc05:203f::/32fc05:203f:ffff:ffff:ffff:ffff:ffff:ffff
65fc05:2040::/32fc05:2040:ffff:ffff:ffff:ffff:ffff:ffff
66fc05:2041::/32fc05:2041:ffff:ffff:ffff:ffff:ffff:ffff
67fc05:2042::/32fc05:2042:ffff:ffff:ffff:ffff:ffff:ffff
68fc05:2043::/32fc05:2043:ffff:ffff:ffff:ffff:ffff:ffff
69fc05:2044::/32fc05:2044:ffff:ffff:ffff:ffff:ffff:ffff
70fc05:2045::/32fc05:2045:ffff:ffff:ffff:ffff:ffff:ffff
71fc05:2046::/32fc05:2046:ffff:ffff:ffff:ffff:ffff:ffff
72fc05:2047::/32fc05:2047:ffff:ffff:ffff:ffff:ffff:ffff
73fc05:2048::/32fc05:2048:ffff:ffff:ffff:ffff:ffff:ffff
74fc05:2049::/32fc05:2049:ffff:ffff:ffff:ffff:ffff:ffff
75fc05:204a::/32fc05:204a:ffff:ffff:ffff:ffff:ffff:ffff
76fc05:204b::/32fc05:204b:ffff:ffff:ffff:ffff:ffff:ffff
77fc05:204c::/32fc05:204c:ffff:ffff:ffff:ffff:ffff:ffff
78fc05:204d::/32fc05:204d:ffff:ffff:ffff:ffff:ffff:ffff
79fc05:204e::/32fc05:204e:ffff:ffff:ffff:ffff:ffff:ffff
80fc05:204f::/32fc05:204f:ffff:ffff:ffff:ffff:ffff:ffff
81fc05:2050::/32fc05:2050:ffff:ffff:ffff:ffff:ffff:ffff
82fc05:2051::/32fc05:2051:ffff:ffff:ffff:ffff:ffff:ffff
83fc05:2052::/32fc05:2052:ffff:ffff:ffff:ffff:ffff:ffff
84fc05:2053::/32fc05:2053:ffff:ffff:ffff:ffff:ffff:ffff
85fc05:2054::/32fc05:2054:ffff:ffff:ffff:ffff:ffff:ffff
86fc05:2055::/32fc05:2055:ffff:ffff:ffff:ffff:ffff:ffff
87fc05:2056::/32fc05:2056:ffff:ffff:ffff:ffff:ffff:ffff
88fc05:2057::/32fc05:2057:ffff:ffff:ffff:ffff:ffff:ffff
89fc05:2058::/32fc05:2058:ffff:ffff:ffff:ffff:ffff:ffff
90fc05:2059::/32fc05:2059:ffff:ffff:ffff:ffff:ffff:ffff
91fc05:205a::/32fc05:205a:ffff:ffff:ffff:ffff:ffff:ffff
92fc05:205b::/32fc05:205b:ffff:ffff:ffff:ffff:ffff:ffff
93fc05:205c::/32fc05:205c:ffff:ffff:ffff:ffff:ffff:ffff
94fc05:205d::/32fc05:205d:ffff:ffff:ffff:ffff:ffff:ffff
95fc05:205e::/32fc05:205e:ffff:ffff:ffff:ffff:ffff:ffff
96fc05:205f::/32fc05:205f:ffff:ffff:ffff:ffff:ffff:ffff
97fc05:2060::/32fc05:2060:ffff:ffff:ffff:ffff:ffff:ffff
98fc05:2061::/32fc05:2061:ffff:ffff:ffff:ffff:ffff:ffff
99fc05:2062::/32fc05:2062:ffff:ffff:ffff:ffff:ffff:ffff
100fc05:2063::/32fc05:2063:ffff:ffff:ffff:ffff:ffff:ffff
101fc05:2064::/32fc05:2064:ffff:ffff:ffff:ffff:ffff:ffff
102fc05:2065::/32fc05:2065:ffff:ffff:ffff:ffff:ffff:ffff
103fc05:2066::/32fc05:2066:ffff:ffff:ffff:ffff:ffff:ffff
104fc05:2067::/32fc05:2067:ffff:ffff:ffff:ffff:ffff:ffff
105fc05:2068::/32fc05:2068:ffff:ffff:ffff:ffff:ffff:ffff
106fc05:2069::/32fc05:2069:ffff:ffff:ffff:ffff:ffff:ffff
107fc05:206a::/32fc05:206a:ffff:ffff:ffff:ffff:ffff:ffff
108fc05:206b::/32fc05:206b:ffff:ffff:ffff:ffff:ffff:ffff
109fc05:206c::/32fc05:206c:ffff:ffff:ffff:ffff:ffff:ffff
110fc05:206d::/32fc05:206d:ffff:ffff:ffff:ffff:ffff:ffff
111fc05:206e::/32fc05:206e:ffff:ffff:ffff:ffff:ffff:ffff
112fc05:206f::/32fc05:206f:ffff:ffff:ffff:ffff:ffff:ffff
113fc05:2070::/32fc05:2070:ffff:ffff:ffff:ffff:ffff:ffff
114fc05:2071::/32fc05:2071:ffff:ffff:ffff:ffff:ffff:ffff
115fc05:2072::/32fc05:2072:ffff:ffff:ffff:ffff:ffff:ffff
116fc05:2073::/32fc05:2073:ffff:ffff:ffff:ffff:ffff:ffff
117fc05:2074::/32fc05:2074:ffff:ffff:ffff:ffff:ffff:ffff
118fc05:2075::/32fc05:2075:ffff:ffff:ffff:ffff:ffff:ffff
119fc05:2076::/32fc05:2076:ffff:ffff:ffff:ffff:ffff:ffff
120fc05:2077::/32fc05:2077:ffff:ffff:ffff:ffff:ffff:ffff
121fc05:2078::/32fc05:2078:ffff:ffff:ffff:ffff:ffff:ffff
122fc05:2079::/32fc05:2079:ffff:ffff:ffff:ffff:ffff:ffff
123fc05:207a::/32fc05:207a:ffff:ffff:ffff:ffff:ffff:ffff
124fc05:207b::/32fc05:207b:ffff:ffff:ffff:ffff:ffff:ffff
125fc05:207c::/32fc05:207c:ffff:ffff:ffff:ffff:ffff:ffff
126fc05:207d::/32fc05:207d:ffff:ffff:ffff:ffff:ffff:ffff
127fc05:207e::/32fc05:207e:ffff:ffff:ffff:ffff:ffff:ffff
128fc05:207f::/32fc05:207f:ffff:ffff:ffff:ffff:ffff:ffff
129fc05:2080::/32fc05:2080:ffff:ffff:ffff:ffff:ffff:ffff
130fc05:2081::/32fc05:2081:ffff:ffff:ffff:ffff:ffff:ffff
131fc05:2082::/32fc05:2082:ffff:ffff:ffff:ffff:ffff:ffff
132fc05:2083::/32fc05:2083:ffff:ffff:ffff:ffff:ffff:ffff
133fc05:2084::/32fc05:2084:ffff:ffff:ffff:ffff:ffff:ffff
134fc05:2085::/32fc05:2085:ffff:ffff:ffff:ffff:ffff:ffff
135fc05:2086::/32fc05:2086:ffff:ffff:ffff:ffff:ffff:ffff
136fc05:2087::/32fc05:2087:ffff:ffff:ffff:ffff:ffff:ffff
137fc05:2088::/32fc05:2088:ffff:ffff:ffff:ffff:ffff:ffff
138fc05:2089::/32fc05:2089:ffff:ffff:ffff:ffff:ffff:ffff
139fc05:208a::/32fc05:208a:ffff:ffff:ffff:ffff:ffff:ffff
140fc05:208b::/32fc05:208b:ffff:ffff:ffff:ffff:ffff:ffff
141fc05:208c::/32fc05:208c:ffff:ffff:ffff:ffff:ffff:ffff
142fc05:208d::/32fc05:208d:ffff:ffff:ffff:ffff:ffff:ffff
143fc05:208e::/32fc05:208e:ffff:ffff:ffff:ffff:ffff:ffff
144fc05:208f::/32fc05:208f:ffff:ffff:ffff:ffff:ffff:ffff
145fc05:2090::/32fc05:2090:ffff:ffff:ffff:ffff:ffff:ffff
146fc05:2091::/32fc05:2091:ffff:ffff:ffff:ffff:ffff:ffff
147fc05:2092::/32fc05:2092:ffff:ffff:ffff:ffff:ffff:ffff
148fc05:2093::/32fc05:2093:ffff:ffff:ffff:ffff:ffff:ffff
149fc05:2094::/32fc05:2094:ffff:ffff:ffff:ffff:ffff:ffff
150fc05:2095::/32fc05:2095:ffff:ffff:ffff:ffff:ffff:ffff
151fc05:2096::/32fc05:2096:ffff:ffff:ffff:ffff:ffff:ffff
152fc05:2097::/32fc05:2097:ffff:ffff:ffff:ffff:ffff:ffff
153fc05:2098::/32fc05:2098:ffff:ffff:ffff:ffff:ffff:ffff
154fc05:2099::/32fc05:2099:ffff:ffff:ffff:ffff:ffff:ffff
155fc05:209a::/32fc05:209a:ffff:ffff:ffff:ffff:ffff:ffff
156fc05:209b::/32fc05:209b:ffff:ffff:ffff:ffff:ffff:ffff
157fc05:209c::/32fc05:209c:ffff:ffff:ffff:ffff:ffff:ffff
158fc05:209d::/32fc05:209d:ffff:ffff:ffff:ffff:ffff:ffff
159fc05:209e::/32fc05:209e:ffff:ffff:ffff:ffff:ffff:ffff
160fc05:209f::/32fc05:209f:ffff:ffff:ffff:ffff:ffff:ffff
161fc05:20a0::/32fc05:20a0:ffff:ffff:ffff:ffff:ffff:ffff
162fc05:20a1::/32fc05:20a1:ffff:ffff:ffff:ffff:ffff:ffff
163fc05:20a2::/32fc05:20a2:ffff:ffff:ffff:ffff:ffff:ffff
164fc05:20a3::/32fc05:20a3:ffff:ffff:ffff:ffff:ffff:ffff
165fc05:20a4::/32fc05:20a4:ffff:ffff:ffff:ffff:ffff:ffff
166fc05:20a5::/32fc05:20a5:ffff:ffff:ffff:ffff:ffff:ffff
167fc05:20a6::/32fc05:20a6:ffff:ffff:ffff:ffff:ffff:ffff
168fc05:20a7::/32fc05:20a7:ffff:ffff:ffff:ffff:ffff:ffff
169fc05:20a8::/32fc05:20a8:ffff:ffff:ffff:ffff:ffff:ffff
170fc05:20a9::/32fc05:20a9:ffff:ffff:ffff:ffff:ffff:ffff
171fc05:20aa::/32fc05:20aa:ffff:ffff:ffff:ffff:ffff:ffff
172fc05:20ab::/32fc05:20ab:ffff:ffff:ffff:ffff:ffff:ffff
173fc05:20ac::/32fc05:20ac:ffff:ffff:ffff:ffff:ffff:ffff
174fc05:20ad::/32fc05:20ad:ffff:ffff:ffff:ffff:ffff:ffff
175fc05:20ae::/32fc05:20ae:ffff:ffff:ffff:ffff:ffff:ffff
176fc05:20af::/32fc05:20af:ffff:ffff:ffff:ffff:ffff:ffff
177fc05:20b0::/32fc05:20b0:ffff:ffff:ffff:ffff:ffff:ffff
178fc05:20b1::/32fc05:20b1:ffff:ffff:ffff:ffff:ffff:ffff
179fc05:20b2::/32fc05:20b2:ffff:ffff:ffff:ffff:ffff:ffff
180fc05:20b3::/32fc05:20b3:ffff:ffff:ffff:ffff:ffff:ffff
181fc05:20b4::/32fc05:20b4:ffff:ffff:ffff:ffff:ffff:ffff
182fc05:20b5::/32fc05:20b5:ffff:ffff:ffff:ffff:ffff:ffff
183fc05:20b6::/32fc05:20b6:ffff:ffff:ffff:ffff:ffff:ffff
184fc05:20b7::/32fc05:20b7:ffff:ffff:ffff:ffff:ffff:ffff
185fc05:20b8::/32fc05:20b8:ffff:ffff:ffff:ffff:ffff:ffff
186fc05:20b9::/32fc05:20b9:ffff:ffff:ffff:ffff:ffff:ffff
187fc05:20ba::/32fc05:20ba:ffff:ffff:ffff:ffff:ffff:ffff
188fc05:20bb::/32fc05:20bb:ffff:ffff:ffff:ffff:ffff:ffff
189fc05:20bc::/32fc05:20bc:ffff:ffff:ffff:ffff:ffff:ffff
190fc05:20bd::/32fc05:20bd:ffff:ffff:ffff:ffff:ffff:ffff
191fc05:20be::/32fc05:20be:ffff:ffff:ffff:ffff:ffff:ffff
192fc05:20bf::/32fc05:20bf:ffff:ffff:ffff:ffff:ffff:ffff
193fc05:20c0::/32fc05:20c0:ffff:ffff:ffff:ffff:ffff:ffff
194fc05:20c1::/32fc05:20c1:ffff:ffff:ffff:ffff:ffff:ffff
195fc05:20c2::/32fc05:20c2:ffff:ffff:ffff:ffff:ffff:ffff
196fc05:20c3::/32fc05:20c3:ffff:ffff:ffff:ffff:ffff:ffff
197fc05:20c4::/32fc05:20c4:ffff:ffff:ffff:ffff:ffff:ffff
198fc05:20c5::/32fc05:20c5:ffff:ffff:ffff:ffff:ffff:ffff
199fc05:20c6::/32fc05:20c6:ffff:ffff:ffff:ffff:ffff:ffff
200fc05:20c7::/32fc05:20c7:ffff:ffff:ffff:ffff:ffff:ffff
201fc05:20c8::/32fc05:20c8:ffff:ffff:ffff:ffff:ffff:ffff
202fc05:20c9::/32fc05:20c9:ffff:ffff:ffff:ffff:ffff:ffff
203fc05:20ca::/32fc05:20ca:ffff:ffff:ffff:ffff:ffff:ffff
204fc05:20cb::/32fc05:20cb:ffff:ffff:ffff:ffff:ffff:ffff
205fc05:20cc::/32fc05:20cc:ffff:ffff:ffff:ffff:ffff:ffff
206fc05:20cd::/32fc05:20cd:ffff:ffff:ffff:ffff:ffff:ffff
207fc05:20ce::/32fc05:20ce:ffff:ffff:ffff:ffff:ffff:ffff
208fc05:20cf::/32fc05:20cf:ffff:ffff:ffff:ffff:ffff:ffff
209fc05:20d0::/32fc05:20d0:ffff:ffff:ffff:ffff:ffff:ffff
210fc05:20d1::/32fc05:20d1:ffff:ffff:ffff:ffff:ffff:ffff
211fc05:20d2::/32fc05:20d2:ffff:ffff:ffff:ffff:ffff:ffff
212fc05:20d3::/32fc05:20d3:ffff:ffff:ffff:ffff:ffff:ffff
213fc05:20d4::/32fc05:20d4:ffff:ffff:ffff:ffff:ffff:ffff
214fc05:20d5::/32fc05:20d5:ffff:ffff:ffff:ffff:ffff:ffff
215fc05:20d6::/32fc05:20d6:ffff:ffff:ffff:ffff:ffff:ffff
216fc05:20d7::/32fc05:20d7:ffff:ffff:ffff:ffff:ffff:ffff
217fc05:20d8::/32fc05:20d8:ffff:ffff:ffff:ffff:ffff:ffff
218fc05:20d9::/32fc05:20d9:ffff:ffff:ffff:ffff:ffff:ffff
219fc05:20da::/32fc05:20da:ffff:ffff:ffff:ffff:ffff:ffff
220fc05:20db::/32fc05:20db:ffff:ffff:ffff:ffff:ffff:ffff
221fc05:20dc::/32fc05:20dc:ffff:ffff:ffff:ffff:ffff:ffff
222fc05:20dd::/32fc05:20dd:ffff:ffff:ffff:ffff:ffff:ffff
223fc05:20de::/32fc05:20de:ffff:ffff:ffff:ffff:ffff:ffff
224fc05:20df::/32fc05:20df:ffff:ffff:ffff:ffff:ffff:ffff
225fc05:20e0::/32fc05:20e0:ffff:ffff:ffff:ffff:ffff:ffff
226fc05:20e1::/32fc05:20e1:ffff:ffff:ffff:ffff:ffff:ffff
227fc05:20e2::/32fc05:20e2:ffff:ffff:ffff:ffff:ffff:ffff
228fc05:20e3::/32fc05:20e3:ffff:ffff:ffff:ffff:ffff:ffff
229fc05:20e4::/32fc05:20e4:ffff:ffff:ffff:ffff:ffff:ffff
230fc05:20e5::/32fc05:20e5:ffff:ffff:ffff:ffff:ffff:ffff
231fc05:20e6::/32fc05:20e6:ffff:ffff:ffff:ffff:ffff:ffff
232fc05:20e7::/32fc05:20e7:ffff:ffff:ffff:ffff:ffff:ffff
233fc05:20e8::/32fc05:20e8:ffff:ffff:ffff:ffff:ffff:ffff
234fc05:20e9::/32fc05:20e9:ffff:ffff:ffff:ffff:ffff:ffff
235fc05:20ea::/32fc05:20ea:ffff:ffff:ffff:ffff:ffff:ffff
236fc05:20eb::/32fc05:20eb:ffff:ffff:ffff:ffff:ffff:ffff
237fc05:20ec::/32fc05:20ec:ffff:ffff:ffff:ffff:ffff:ffff
238fc05:20ed::/32fc05:20ed:ffff:ffff:ffff:ffff:ffff:ffff
239fc05:20ee::/32fc05:20ee:ffff:ffff:ffff:ffff:ffff:ffff
240fc05:20ef::/32fc05:20ef:ffff:ffff:ffff:ffff:ffff:ffff
241fc05:20f0::/32fc05:20f0:ffff:ffff:ffff:ffff:ffff:ffff
242fc05:20f1::/32fc05:20f1:ffff:ffff:ffff:ffff:ffff:ffff
243fc05:20f2::/32fc05:20f2:ffff:ffff:ffff:ffff:ffff:ffff
244fc05:20f3::/32fc05:20f3:ffff:ffff:ffff:ffff:ffff:ffff
245fc05:20f4::/32fc05:20f4:ffff:ffff:ffff:ffff:ffff:ffff
246fc05:20f5::/32fc05:20f5:ffff:ffff:ffff:ffff:ffff:ffff
247fc05:20f6::/32fc05:20f6:ffff:ffff:ffff:ffff:ffff:ffff
248fc05:20f7::/32fc05:20f7:ffff:ffff:ffff:ffff:ffff:ffff
249fc05:20f8::/32fc05:20f8:ffff:ffff:ffff:ffff:ffff:ffff
250fc05:20f9::/32fc05:20f9:ffff:ffff:ffff:ffff:ffff:ffff
251fc05:20fa::/32fc05:20fa:ffff:ffff:ffff:ffff:ffff:ffff
252fc05:20fb::/32fc05:20fb:ffff:ffff:ffff:ffff:ffff:ffff
253fc05:20fc::/32fc05:20fc:ffff:ffff:ffff:ffff:ffff:ffff
254fc05:20fd::/32fc05:20fd:ffff:ffff:ffff:ffff:ffff:ffff
255fc05:20fe::/32fc05:20fe:ffff:ffff:ffff:ffff:ffff:ffff
256fc05:20ff::/32fc05:20ff: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.