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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
fcb9::/16
First address
fcb9::
Last address
fcb9: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
fcb9:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
9.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)

fcb9::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fcb9::/24fcb9:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fcb9:100::/24fcb9:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fcb9:200::/24fcb9:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fcb9:300::/24fcb9:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fcb9:400::/24fcb9:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fcb9:500::/24fcb9:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fcb9:600::/24fcb9:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fcb9:700::/24fcb9:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fcb9:800::/24fcb9:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fcb9:900::/24fcb9:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fcb9:a00::/24fcb9:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fcb9:b00::/24fcb9:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fcb9:c00::/24fcb9:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fcb9:d00::/24fcb9:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fcb9:e00::/24fcb9:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fcb9:f00::/24fcb9:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fcb9:1000::/24fcb9:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fcb9:1100::/24fcb9:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fcb9:1200::/24fcb9:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fcb9:1300::/24fcb9:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fcb9:1400::/24fcb9:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fcb9:1500::/24fcb9:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fcb9:1600::/24fcb9:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fcb9:1700::/24fcb9:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fcb9:1800::/24fcb9:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fcb9:1900::/24fcb9:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fcb9:1a00::/24fcb9:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fcb9:1b00::/24fcb9:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fcb9:1c00::/24fcb9:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fcb9:1d00::/24fcb9:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fcb9:1e00::/24fcb9:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fcb9:1f00::/24fcb9:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fcb9:2000::/24fcb9:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fcb9:2100::/24fcb9:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fcb9:2200::/24fcb9:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fcb9:2300::/24fcb9:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fcb9:2400::/24fcb9:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fcb9:2500::/24fcb9:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fcb9:2600::/24fcb9:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fcb9:2700::/24fcb9:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fcb9:2800::/24fcb9:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fcb9:2900::/24fcb9:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fcb9:2a00::/24fcb9:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fcb9:2b00::/24fcb9:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fcb9:2c00::/24fcb9:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fcb9:2d00::/24fcb9:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fcb9:2e00::/24fcb9:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fcb9:2f00::/24fcb9:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fcb9:3000::/24fcb9:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fcb9:3100::/24fcb9:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fcb9:3200::/24fcb9:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fcb9:3300::/24fcb9:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fcb9:3400::/24fcb9:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fcb9:3500::/24fcb9:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fcb9:3600::/24fcb9:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fcb9:3700::/24fcb9:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fcb9:3800::/24fcb9:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fcb9:3900::/24fcb9:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fcb9:3a00::/24fcb9:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fcb9:3b00::/24fcb9:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fcb9:3c00::/24fcb9:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fcb9:3d00::/24fcb9:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fcb9:3e00::/24fcb9:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fcb9:3f00::/24fcb9:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fcb9:4000::/24fcb9:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fcb9:4100::/24fcb9:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fcb9:4200::/24fcb9:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fcb9:4300::/24fcb9:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fcb9:4400::/24fcb9:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fcb9:4500::/24fcb9:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fcb9:4600::/24fcb9:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fcb9:4700::/24fcb9:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fcb9:4800::/24fcb9:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fcb9:4900::/24fcb9:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fcb9:4a00::/24fcb9:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fcb9:4b00::/24fcb9:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fcb9:4c00::/24fcb9:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fcb9:4d00::/24fcb9:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fcb9:4e00::/24fcb9:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fcb9:4f00::/24fcb9:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fcb9:5000::/24fcb9:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fcb9:5100::/24fcb9:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fcb9:5200::/24fcb9:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fcb9:5300::/24fcb9:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fcb9:5400::/24fcb9:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fcb9:5500::/24fcb9:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fcb9:5600::/24fcb9:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fcb9:5700::/24fcb9:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fcb9:5800::/24fcb9:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fcb9:5900::/24fcb9:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fcb9:5a00::/24fcb9:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fcb9:5b00::/24fcb9:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fcb9:5c00::/24fcb9:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fcb9:5d00::/24fcb9:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fcb9:5e00::/24fcb9:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fcb9:5f00::/24fcb9:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fcb9:6000::/24fcb9:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fcb9:6100::/24fcb9:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fcb9:6200::/24fcb9:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fcb9:6300::/24fcb9:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fcb9:6400::/24fcb9:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fcb9:6500::/24fcb9:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fcb9:6600::/24fcb9:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fcb9:6700::/24fcb9:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fcb9:6800::/24fcb9:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fcb9:6900::/24fcb9:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fcb9:6a00::/24fcb9:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fcb9:6b00::/24fcb9:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fcb9:6c00::/24fcb9:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fcb9:6d00::/24fcb9:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fcb9:6e00::/24fcb9:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fcb9:6f00::/24fcb9:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fcb9:7000::/24fcb9:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fcb9:7100::/24fcb9:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fcb9:7200::/24fcb9:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fcb9:7300::/24fcb9:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fcb9:7400::/24fcb9:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fcb9:7500::/24fcb9:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fcb9:7600::/24fcb9:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fcb9:7700::/24fcb9:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fcb9:7800::/24fcb9:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fcb9:7900::/24fcb9:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fcb9:7a00::/24fcb9:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fcb9:7b00::/24fcb9:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fcb9:7c00::/24fcb9:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fcb9:7d00::/24fcb9:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fcb9:7e00::/24fcb9:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fcb9:7f00::/24fcb9:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fcb9:8000::/24fcb9:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fcb9:8100::/24fcb9:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fcb9:8200::/24fcb9:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fcb9:8300::/24fcb9:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fcb9:8400::/24fcb9:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fcb9:8500::/24fcb9:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fcb9:8600::/24fcb9:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fcb9:8700::/24fcb9:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fcb9:8800::/24fcb9:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fcb9:8900::/24fcb9:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fcb9:8a00::/24fcb9:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fcb9:8b00::/24fcb9:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fcb9:8c00::/24fcb9:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fcb9:8d00::/24fcb9:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fcb9:8e00::/24fcb9:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fcb9:8f00::/24fcb9:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fcb9:9000::/24fcb9:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fcb9:9100::/24fcb9:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fcb9:9200::/24fcb9:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fcb9:9300::/24fcb9:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fcb9:9400::/24fcb9:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fcb9:9500::/24fcb9:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fcb9:9600::/24fcb9:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fcb9:9700::/24fcb9:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fcb9:9800::/24fcb9:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fcb9:9900::/24fcb9:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fcb9:9a00::/24fcb9:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fcb9:9b00::/24fcb9:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fcb9:9c00::/24fcb9:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fcb9:9d00::/24fcb9:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fcb9:9e00::/24fcb9:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fcb9:9f00::/24fcb9:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fcb9:a000::/24fcb9:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fcb9:a100::/24fcb9:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fcb9:a200::/24fcb9:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fcb9:a300::/24fcb9:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fcb9:a400::/24fcb9:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fcb9:a500::/24fcb9:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fcb9:a600::/24fcb9:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fcb9:a700::/24fcb9:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fcb9:a800::/24fcb9:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fcb9:a900::/24fcb9:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fcb9:aa00::/24fcb9:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fcb9:ab00::/24fcb9:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fcb9:ac00::/24fcb9:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fcb9:ad00::/24fcb9:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fcb9:ae00::/24fcb9:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fcb9:af00::/24fcb9:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fcb9:b000::/24fcb9:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fcb9:b100::/24fcb9:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fcb9:b200::/24fcb9:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fcb9:b300::/24fcb9:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fcb9:b400::/24fcb9:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fcb9:b500::/24fcb9:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fcb9:b600::/24fcb9:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fcb9:b700::/24fcb9:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fcb9:b800::/24fcb9:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fcb9:b900::/24fcb9:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fcb9:ba00::/24fcb9:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fcb9:bb00::/24fcb9:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fcb9:bc00::/24fcb9:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fcb9:bd00::/24fcb9:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fcb9:be00::/24fcb9:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fcb9:bf00::/24fcb9:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fcb9:c000::/24fcb9:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fcb9:c100::/24fcb9:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fcb9:c200::/24fcb9:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fcb9:c300::/24fcb9:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fcb9:c400::/24fcb9:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fcb9:c500::/24fcb9:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fcb9:c600::/24fcb9:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fcb9:c700::/24fcb9:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fcb9:c800::/24fcb9:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fcb9:c900::/24fcb9:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fcb9:ca00::/24fcb9:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fcb9:cb00::/24fcb9:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fcb9:cc00::/24fcb9:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fcb9:cd00::/24fcb9:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fcb9:ce00::/24fcb9:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fcb9:cf00::/24fcb9:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fcb9:d000::/24fcb9:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fcb9:d100::/24fcb9:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fcb9:d200::/24fcb9:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fcb9:d300::/24fcb9:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fcb9:d400::/24fcb9:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fcb9:d500::/24fcb9:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fcb9:d600::/24fcb9:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fcb9:d700::/24fcb9:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fcb9:d800::/24fcb9:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fcb9:d900::/24fcb9:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fcb9:da00::/24fcb9:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fcb9:db00::/24fcb9:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fcb9:dc00::/24fcb9:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fcb9:dd00::/24fcb9:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fcb9:de00::/24fcb9:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fcb9:df00::/24fcb9:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fcb9:e000::/24fcb9:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fcb9:e100::/24fcb9:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fcb9:e200::/24fcb9:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fcb9:e300::/24fcb9:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fcb9:e400::/24fcb9:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fcb9:e500::/24fcb9:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fcb9:e600::/24fcb9:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fcb9:e700::/24fcb9:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fcb9:e800::/24fcb9:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fcb9:e900::/24fcb9:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fcb9:ea00::/24fcb9:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fcb9:eb00::/24fcb9:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fcb9:ec00::/24fcb9:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fcb9:ed00::/24fcb9:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fcb9:ee00::/24fcb9:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fcb9:ef00::/24fcb9:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fcb9:f000::/24fcb9:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fcb9:f100::/24fcb9:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fcb9:f200::/24fcb9:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fcb9:f300::/24fcb9:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fcb9:f400::/24fcb9:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fcb9:f500::/24fcb9:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fcb9:f600::/24fcb9:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fcb9:f700::/24fcb9:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fcb9:f800::/24fcb9:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fcb9:f900::/24fcb9:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fcb9:fa00::/24fcb9:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fcb9:fb00::/24fcb9:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fcb9:fc00::/24fcb9:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fcb9:fd00::/24fcb9:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fcb9:fe00::/24fcb9:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fcb9:ff00::/24fcb9: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.