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

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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Prefix/16
Addresses2^112
/64 networks2^48
Network
fcbb::/16
First address
fcbb::
Last address
fcbb:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
fcbb:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
b.b.c.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fcbb::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fcbb::/24fcbb:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fcbb:100::/24fcbb:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fcbb:200::/24fcbb:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fcbb:300::/24fcbb:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fcbb:400::/24fcbb:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fcbb:500::/24fcbb:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fcbb:600::/24fcbb:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fcbb:700::/24fcbb:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fcbb:800::/24fcbb:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fcbb:900::/24fcbb:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fcbb:a00::/24fcbb:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fcbb:b00::/24fcbb:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fcbb:c00::/24fcbb:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fcbb:d00::/24fcbb:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fcbb:e00::/24fcbb:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fcbb:f00::/24fcbb:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fcbb:1000::/24fcbb:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fcbb:1100::/24fcbb:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fcbb:1200::/24fcbb:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fcbb:1300::/24fcbb:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fcbb:1400::/24fcbb:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fcbb:1500::/24fcbb:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fcbb:1600::/24fcbb:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fcbb:1700::/24fcbb:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fcbb:1800::/24fcbb:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fcbb:1900::/24fcbb:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fcbb:1a00::/24fcbb:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fcbb:1b00::/24fcbb:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fcbb:1c00::/24fcbb:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fcbb:1d00::/24fcbb:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fcbb:1e00::/24fcbb:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fcbb:1f00::/24fcbb:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fcbb:2000::/24fcbb:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fcbb:2100::/24fcbb:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fcbb:2200::/24fcbb:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fcbb:2300::/24fcbb:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fcbb:2400::/24fcbb:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fcbb:2500::/24fcbb:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fcbb:2600::/24fcbb:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fcbb:2700::/24fcbb:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fcbb:2800::/24fcbb:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fcbb:2900::/24fcbb:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fcbb:2a00::/24fcbb:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fcbb:2b00::/24fcbb:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fcbb:2c00::/24fcbb:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fcbb:2d00::/24fcbb:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fcbb:2e00::/24fcbb:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fcbb:2f00::/24fcbb:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fcbb:3000::/24fcbb:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fcbb:3100::/24fcbb:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fcbb:3200::/24fcbb:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fcbb:3300::/24fcbb:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fcbb:3400::/24fcbb:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fcbb:3500::/24fcbb:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fcbb:3600::/24fcbb:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fcbb:3700::/24fcbb:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fcbb:3800::/24fcbb:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fcbb:3900::/24fcbb:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fcbb:3a00::/24fcbb:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fcbb:3b00::/24fcbb:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fcbb:3c00::/24fcbb:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fcbb:3d00::/24fcbb:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fcbb:3e00::/24fcbb:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fcbb:3f00::/24fcbb:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fcbb:4000::/24fcbb:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fcbb:4100::/24fcbb:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fcbb:4200::/24fcbb:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fcbb:4300::/24fcbb:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fcbb:4400::/24fcbb:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fcbb:4500::/24fcbb:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fcbb:4600::/24fcbb:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fcbb:4700::/24fcbb:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fcbb:4800::/24fcbb:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fcbb:4900::/24fcbb:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fcbb:4a00::/24fcbb:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fcbb:4b00::/24fcbb:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fcbb:4c00::/24fcbb:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fcbb:4d00::/24fcbb:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fcbb:4e00::/24fcbb:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fcbb:4f00::/24fcbb:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fcbb:5000::/24fcbb:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fcbb:5100::/24fcbb:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fcbb:5200::/24fcbb:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fcbb:5300::/24fcbb:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fcbb:5400::/24fcbb:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fcbb:5500::/24fcbb:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fcbb:5600::/24fcbb:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fcbb:5700::/24fcbb:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fcbb:5800::/24fcbb:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fcbb:5900::/24fcbb:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fcbb:5a00::/24fcbb:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fcbb:5b00::/24fcbb:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fcbb:5c00::/24fcbb:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fcbb:5d00::/24fcbb:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fcbb:5e00::/24fcbb:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fcbb:5f00::/24fcbb:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fcbb:6000::/24fcbb:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fcbb:6100::/24fcbb:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fcbb:6200::/24fcbb:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fcbb:6300::/24fcbb:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fcbb:6400::/24fcbb:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fcbb:6500::/24fcbb:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fcbb:6600::/24fcbb:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fcbb:6700::/24fcbb:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fcbb:6800::/24fcbb:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fcbb:6900::/24fcbb:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fcbb:6a00::/24fcbb:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fcbb:6b00::/24fcbb:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fcbb:6c00::/24fcbb:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fcbb:6d00::/24fcbb:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fcbb:6e00::/24fcbb:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fcbb:6f00::/24fcbb:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fcbb:7000::/24fcbb:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fcbb:7100::/24fcbb:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fcbb:7200::/24fcbb:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fcbb:7300::/24fcbb:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fcbb:7400::/24fcbb:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fcbb:7500::/24fcbb:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fcbb:7600::/24fcbb:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fcbb:7700::/24fcbb:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fcbb:7800::/24fcbb:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fcbb:7900::/24fcbb:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fcbb:7a00::/24fcbb:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fcbb:7b00::/24fcbb:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fcbb:7c00::/24fcbb:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fcbb:7d00::/24fcbb:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fcbb:7e00::/24fcbb:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fcbb:7f00::/24fcbb:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fcbb:8000::/24fcbb:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fcbb:8100::/24fcbb:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fcbb:8200::/24fcbb:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fcbb:8300::/24fcbb:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fcbb:8400::/24fcbb:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fcbb:8500::/24fcbb:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fcbb:8600::/24fcbb:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fcbb:8700::/24fcbb:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fcbb:8800::/24fcbb:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fcbb:8900::/24fcbb:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fcbb:8a00::/24fcbb:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fcbb:8b00::/24fcbb:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fcbb:8c00::/24fcbb:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fcbb:8d00::/24fcbb:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fcbb:8e00::/24fcbb:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fcbb:8f00::/24fcbb:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fcbb:9000::/24fcbb:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fcbb:9100::/24fcbb:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fcbb:9200::/24fcbb:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fcbb:9300::/24fcbb:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fcbb:9400::/24fcbb:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fcbb:9500::/24fcbb:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fcbb:9600::/24fcbb:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fcbb:9700::/24fcbb:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fcbb:9800::/24fcbb:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fcbb:9900::/24fcbb:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fcbb:9a00::/24fcbb:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fcbb:9b00::/24fcbb:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fcbb:9c00::/24fcbb:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fcbb:9d00::/24fcbb:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fcbb:9e00::/24fcbb:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fcbb:9f00::/24fcbb:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fcbb:a000::/24fcbb:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fcbb:a100::/24fcbb:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fcbb:a200::/24fcbb:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fcbb:a300::/24fcbb:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fcbb:a400::/24fcbb:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fcbb:a500::/24fcbb:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fcbb:a600::/24fcbb:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fcbb:a700::/24fcbb:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fcbb:a800::/24fcbb:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fcbb:a900::/24fcbb:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fcbb:aa00::/24fcbb:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fcbb:ab00::/24fcbb:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fcbb:ac00::/24fcbb:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fcbb:ad00::/24fcbb:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fcbb:ae00::/24fcbb:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fcbb:af00::/24fcbb:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fcbb:b000::/24fcbb:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fcbb:b100::/24fcbb:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fcbb:b200::/24fcbb:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fcbb:b300::/24fcbb:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fcbb:b400::/24fcbb:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fcbb:b500::/24fcbb:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fcbb:b600::/24fcbb:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fcbb:b700::/24fcbb:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fcbb:b800::/24fcbb:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fcbb:b900::/24fcbb:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fcbb:ba00::/24fcbb:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fcbb:bb00::/24fcbb:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fcbb:bc00::/24fcbb:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fcbb:bd00::/24fcbb:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fcbb:be00::/24fcbb:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fcbb:bf00::/24fcbb:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fcbb:c000::/24fcbb:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fcbb:c100::/24fcbb:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fcbb:c200::/24fcbb:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fcbb:c300::/24fcbb:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fcbb:c400::/24fcbb:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fcbb:c500::/24fcbb:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fcbb:c600::/24fcbb:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fcbb:c700::/24fcbb:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fcbb:c800::/24fcbb:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fcbb:c900::/24fcbb:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fcbb:ca00::/24fcbb:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fcbb:cb00::/24fcbb:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fcbb:cc00::/24fcbb:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fcbb:cd00::/24fcbb:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fcbb:ce00::/24fcbb:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fcbb:cf00::/24fcbb:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fcbb:d000::/24fcbb:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fcbb:d100::/24fcbb:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fcbb:d200::/24fcbb:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fcbb:d300::/24fcbb:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fcbb:d400::/24fcbb:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fcbb:d500::/24fcbb:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fcbb:d600::/24fcbb:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fcbb:d700::/24fcbb:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fcbb:d800::/24fcbb:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fcbb:d900::/24fcbb:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fcbb:da00::/24fcbb:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fcbb:db00::/24fcbb:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fcbb:dc00::/24fcbb:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fcbb:dd00::/24fcbb:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fcbb:de00::/24fcbb:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fcbb:df00::/24fcbb:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fcbb:e000::/24fcbb:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fcbb:e100::/24fcbb:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fcbb:e200::/24fcbb:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fcbb:e300::/24fcbb:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fcbb:e400::/24fcbb:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fcbb:e500::/24fcbb:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fcbb:e600::/24fcbb:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fcbb:e700::/24fcbb:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fcbb:e800::/24fcbb:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fcbb:e900::/24fcbb:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fcbb:ea00::/24fcbb:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fcbb:eb00::/24fcbb:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fcbb:ec00::/24fcbb:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fcbb:ed00::/24fcbb:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fcbb:ee00::/24fcbb:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fcbb:ef00::/24fcbb:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fcbb:f000::/24fcbb:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fcbb:f100::/24fcbb:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fcbb:f200::/24fcbb:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fcbb:f300::/24fcbb:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fcbb:f400::/24fcbb:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fcbb:f500::/24fcbb:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fcbb:f600::/24fcbb:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fcbb:f700::/24fcbb:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fcbb:f800::/24fcbb:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fcbb:f900::/24fcbb:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fcbb:fa00::/24fcbb:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fcbb:fb00::/24fcbb:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fcbb:fc00::/24fcbb:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fcbb:fd00::/24fcbb:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fcbb:fe00::/24fcbb:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fcbb:ff00::/24fcbb:ffff: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.