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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
fcb6::/16
First address
fcb6::
Last address
fcb6: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
fcb6:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
6.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)

fcb6::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fcb6::/24fcb6:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fcb6:100::/24fcb6:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fcb6:200::/24fcb6:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fcb6:300::/24fcb6:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fcb6:400::/24fcb6:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fcb6:500::/24fcb6:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fcb6:600::/24fcb6:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fcb6:700::/24fcb6:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fcb6:800::/24fcb6:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fcb6:900::/24fcb6:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fcb6:a00::/24fcb6:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fcb6:b00::/24fcb6:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fcb6:c00::/24fcb6:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fcb6:d00::/24fcb6:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fcb6:e00::/24fcb6:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fcb6:f00::/24fcb6:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fcb6:1000::/24fcb6:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fcb6:1100::/24fcb6:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fcb6:1200::/24fcb6:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fcb6:1300::/24fcb6:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fcb6:1400::/24fcb6:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fcb6:1500::/24fcb6:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fcb6:1600::/24fcb6:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fcb6:1700::/24fcb6:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fcb6:1800::/24fcb6:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fcb6:1900::/24fcb6:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fcb6:1a00::/24fcb6:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fcb6:1b00::/24fcb6:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fcb6:1c00::/24fcb6:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fcb6:1d00::/24fcb6:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fcb6:1e00::/24fcb6:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fcb6:1f00::/24fcb6:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fcb6:2000::/24fcb6:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fcb6:2100::/24fcb6:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fcb6:2200::/24fcb6:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fcb6:2300::/24fcb6:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fcb6:2400::/24fcb6:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fcb6:2500::/24fcb6:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fcb6:2600::/24fcb6:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fcb6:2700::/24fcb6:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fcb6:2800::/24fcb6:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fcb6:2900::/24fcb6:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fcb6:2a00::/24fcb6:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fcb6:2b00::/24fcb6:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fcb6:2c00::/24fcb6:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fcb6:2d00::/24fcb6:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fcb6:2e00::/24fcb6:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fcb6:2f00::/24fcb6:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fcb6:3000::/24fcb6:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fcb6:3100::/24fcb6:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fcb6:3200::/24fcb6:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fcb6:3300::/24fcb6:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fcb6:3400::/24fcb6:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fcb6:3500::/24fcb6:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fcb6:3600::/24fcb6:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fcb6:3700::/24fcb6:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fcb6:3800::/24fcb6:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fcb6:3900::/24fcb6:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fcb6:3a00::/24fcb6:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fcb6:3b00::/24fcb6:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fcb6:3c00::/24fcb6:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fcb6:3d00::/24fcb6:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fcb6:3e00::/24fcb6:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fcb6:3f00::/24fcb6:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fcb6:4000::/24fcb6:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fcb6:4100::/24fcb6:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fcb6:4200::/24fcb6:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fcb6:4300::/24fcb6:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fcb6:4400::/24fcb6:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fcb6:4500::/24fcb6:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fcb6:4600::/24fcb6:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fcb6:4700::/24fcb6:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fcb6:4800::/24fcb6:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fcb6:4900::/24fcb6:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fcb6:4a00::/24fcb6:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fcb6:4b00::/24fcb6:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fcb6:4c00::/24fcb6:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fcb6:4d00::/24fcb6:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fcb6:4e00::/24fcb6:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fcb6:4f00::/24fcb6:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fcb6:5000::/24fcb6:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fcb6:5100::/24fcb6:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fcb6:5200::/24fcb6:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fcb6:5300::/24fcb6:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fcb6:5400::/24fcb6:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fcb6:5500::/24fcb6:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fcb6:5600::/24fcb6:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fcb6:5700::/24fcb6:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fcb6:5800::/24fcb6:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fcb6:5900::/24fcb6:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fcb6:5a00::/24fcb6:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fcb6:5b00::/24fcb6:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fcb6:5c00::/24fcb6:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fcb6:5d00::/24fcb6:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fcb6:5e00::/24fcb6:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fcb6:5f00::/24fcb6:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fcb6:6000::/24fcb6:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fcb6:6100::/24fcb6:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fcb6:6200::/24fcb6:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fcb6:6300::/24fcb6:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fcb6:6400::/24fcb6:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fcb6:6500::/24fcb6:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fcb6:6600::/24fcb6:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fcb6:6700::/24fcb6:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fcb6:6800::/24fcb6:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fcb6:6900::/24fcb6:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fcb6:6a00::/24fcb6:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fcb6:6b00::/24fcb6:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fcb6:6c00::/24fcb6:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fcb6:6d00::/24fcb6:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fcb6:6e00::/24fcb6:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fcb6:6f00::/24fcb6:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fcb6:7000::/24fcb6:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fcb6:7100::/24fcb6:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fcb6:7200::/24fcb6:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fcb6:7300::/24fcb6:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fcb6:7400::/24fcb6:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fcb6:7500::/24fcb6:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fcb6:7600::/24fcb6:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fcb6:7700::/24fcb6:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fcb6:7800::/24fcb6:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fcb6:7900::/24fcb6:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fcb6:7a00::/24fcb6:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fcb6:7b00::/24fcb6:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fcb6:7c00::/24fcb6:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fcb6:7d00::/24fcb6:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fcb6:7e00::/24fcb6:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fcb6:7f00::/24fcb6:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fcb6:8000::/24fcb6:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fcb6:8100::/24fcb6:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fcb6:8200::/24fcb6:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fcb6:8300::/24fcb6:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fcb6:8400::/24fcb6:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fcb6:8500::/24fcb6:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fcb6:8600::/24fcb6:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fcb6:8700::/24fcb6:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fcb6:8800::/24fcb6:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fcb6:8900::/24fcb6:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fcb6:8a00::/24fcb6:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fcb6:8b00::/24fcb6:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fcb6:8c00::/24fcb6:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fcb6:8d00::/24fcb6:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fcb6:8e00::/24fcb6:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fcb6:8f00::/24fcb6:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fcb6:9000::/24fcb6:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fcb6:9100::/24fcb6:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fcb6:9200::/24fcb6:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fcb6:9300::/24fcb6:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fcb6:9400::/24fcb6:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fcb6:9500::/24fcb6:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fcb6:9600::/24fcb6:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fcb6:9700::/24fcb6:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fcb6:9800::/24fcb6:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fcb6:9900::/24fcb6:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fcb6:9a00::/24fcb6:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fcb6:9b00::/24fcb6:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fcb6:9c00::/24fcb6:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fcb6:9d00::/24fcb6:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fcb6:9e00::/24fcb6:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fcb6:9f00::/24fcb6:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fcb6:a000::/24fcb6:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fcb6:a100::/24fcb6:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fcb6:a200::/24fcb6:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fcb6:a300::/24fcb6:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fcb6:a400::/24fcb6:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fcb6:a500::/24fcb6:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fcb6:a600::/24fcb6:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fcb6:a700::/24fcb6:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fcb6:a800::/24fcb6:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fcb6:a900::/24fcb6:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fcb6:aa00::/24fcb6:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fcb6:ab00::/24fcb6:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fcb6:ac00::/24fcb6:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fcb6:ad00::/24fcb6:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fcb6:ae00::/24fcb6:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fcb6:af00::/24fcb6:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fcb6:b000::/24fcb6:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fcb6:b100::/24fcb6:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fcb6:b200::/24fcb6:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fcb6:b300::/24fcb6:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fcb6:b400::/24fcb6:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fcb6:b500::/24fcb6:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fcb6:b600::/24fcb6:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fcb6:b700::/24fcb6:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fcb6:b800::/24fcb6:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fcb6:b900::/24fcb6:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fcb6:ba00::/24fcb6:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fcb6:bb00::/24fcb6:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fcb6:bc00::/24fcb6:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fcb6:bd00::/24fcb6:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fcb6:be00::/24fcb6:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fcb6:bf00::/24fcb6:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fcb6:c000::/24fcb6:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fcb6:c100::/24fcb6:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fcb6:c200::/24fcb6:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fcb6:c300::/24fcb6:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fcb6:c400::/24fcb6:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fcb6:c500::/24fcb6:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fcb6:c600::/24fcb6:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fcb6:c700::/24fcb6:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fcb6:c800::/24fcb6:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fcb6:c900::/24fcb6:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fcb6:ca00::/24fcb6:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fcb6:cb00::/24fcb6:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fcb6:cc00::/24fcb6:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fcb6:cd00::/24fcb6:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fcb6:ce00::/24fcb6:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fcb6:cf00::/24fcb6:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fcb6:d000::/24fcb6:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fcb6:d100::/24fcb6:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fcb6:d200::/24fcb6:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fcb6:d300::/24fcb6:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fcb6:d400::/24fcb6:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fcb6:d500::/24fcb6:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fcb6:d600::/24fcb6:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fcb6:d700::/24fcb6:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fcb6:d800::/24fcb6:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fcb6:d900::/24fcb6:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fcb6:da00::/24fcb6:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fcb6:db00::/24fcb6:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fcb6:dc00::/24fcb6:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fcb6:dd00::/24fcb6:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fcb6:de00::/24fcb6:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fcb6:df00::/24fcb6:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fcb6:e000::/24fcb6:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fcb6:e100::/24fcb6:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fcb6:e200::/24fcb6:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fcb6:e300::/24fcb6:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fcb6:e400::/24fcb6:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fcb6:e500::/24fcb6:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fcb6:e600::/24fcb6:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fcb6:e700::/24fcb6:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fcb6:e800::/24fcb6:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fcb6:e900::/24fcb6:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fcb6:ea00::/24fcb6:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fcb6:eb00::/24fcb6:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fcb6:ec00::/24fcb6:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fcb6:ed00::/24fcb6:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fcb6:ee00::/24fcb6:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fcb6:ef00::/24fcb6:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fcb6:f000::/24fcb6:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fcb6:f100::/24fcb6:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fcb6:f200::/24fcb6:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fcb6:f300::/24fcb6:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fcb6:f400::/24fcb6:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fcb6:f500::/24fcb6:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fcb6:f600::/24fcb6:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fcb6:f700::/24fcb6:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fcb6:f800::/24fcb6:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fcb6:f900::/24fcb6:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fcb6:fa00::/24fcb6:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fcb6:fb00::/24fcb6:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fcb6:fc00::/24fcb6:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fcb6:fd00::/24fcb6:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fcb6:fe00::/24fcb6:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fcb6:ff00::/24fcb6: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.