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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/32
Addresses2^96
/64 networks2^32
Network
261b:dd::/32
First address
261b:dd::
Last address
261b:dd:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
79,228,162,514,264,337,593,543,950,336 (2^96)
/64 networks (LANs)
4,294,967,296
Full form
261b:00dd:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
d.d.0.0.b.1.6.2.ip6.arpa
Split into smaller subnets/40
/33 (2)/34 (4)/35 (8)/36 (16)/40 (256)/44 (4,096)/48 (65,536)

261b:dd::/32 makes 256 subnets of /40.

Subnets
#SubnetLast address
1261b:dd::/40261b:dd:ff:ffff:ffff:ffff:ffff:ffff
2261b:dd:100::/40261b:dd:1ff:ffff:ffff:ffff:ffff:ffff
3261b:dd:200::/40261b:dd:2ff:ffff:ffff:ffff:ffff:ffff
4261b:dd:300::/40261b:dd:3ff:ffff:ffff:ffff:ffff:ffff
5261b:dd:400::/40261b:dd:4ff:ffff:ffff:ffff:ffff:ffff
6261b:dd:500::/40261b:dd:5ff:ffff:ffff:ffff:ffff:ffff
7261b:dd:600::/40261b:dd:6ff:ffff:ffff:ffff:ffff:ffff
8261b:dd:700::/40261b:dd:7ff:ffff:ffff:ffff:ffff:ffff
9261b:dd:800::/40261b:dd:8ff:ffff:ffff:ffff:ffff:ffff
10261b:dd:900::/40261b:dd:9ff:ffff:ffff:ffff:ffff:ffff
11261b:dd:a00::/40261b:dd:aff:ffff:ffff:ffff:ffff:ffff
12261b:dd:b00::/40261b:dd:bff:ffff:ffff:ffff:ffff:ffff
13261b:dd:c00::/40261b:dd:cff:ffff:ffff:ffff:ffff:ffff
14261b:dd:d00::/40261b:dd:dff:ffff:ffff:ffff:ffff:ffff
15261b:dd:e00::/40261b:dd:eff:ffff:ffff:ffff:ffff:ffff
16261b:dd:f00::/40261b:dd:fff:ffff:ffff:ffff:ffff:ffff
17261b:dd:1000::/40261b:dd:10ff:ffff:ffff:ffff:ffff:ffff
18261b:dd:1100::/40261b:dd:11ff:ffff:ffff:ffff:ffff:ffff
19261b:dd:1200::/40261b:dd:12ff:ffff:ffff:ffff:ffff:ffff
20261b:dd:1300::/40261b:dd:13ff:ffff:ffff:ffff:ffff:ffff
21261b:dd:1400::/40261b:dd:14ff:ffff:ffff:ffff:ffff:ffff
22261b:dd:1500::/40261b:dd:15ff:ffff:ffff:ffff:ffff:ffff
23261b:dd:1600::/40261b:dd:16ff:ffff:ffff:ffff:ffff:ffff
24261b:dd:1700::/40261b:dd:17ff:ffff:ffff:ffff:ffff:ffff
25261b:dd:1800::/40261b:dd:18ff:ffff:ffff:ffff:ffff:ffff
26261b:dd:1900::/40261b:dd:19ff:ffff:ffff:ffff:ffff:ffff
27261b:dd:1a00::/40261b:dd:1aff:ffff:ffff:ffff:ffff:ffff
28261b:dd:1b00::/40261b:dd:1bff:ffff:ffff:ffff:ffff:ffff
29261b:dd:1c00::/40261b:dd:1cff:ffff:ffff:ffff:ffff:ffff
30261b:dd:1d00::/40261b:dd:1dff:ffff:ffff:ffff:ffff:ffff
31261b:dd:1e00::/40261b:dd:1eff:ffff:ffff:ffff:ffff:ffff
32261b:dd:1f00::/40261b:dd:1fff:ffff:ffff:ffff:ffff:ffff
33261b:dd:2000::/40261b:dd:20ff:ffff:ffff:ffff:ffff:ffff
34261b:dd:2100::/40261b:dd:21ff:ffff:ffff:ffff:ffff:ffff
35261b:dd:2200::/40261b:dd:22ff:ffff:ffff:ffff:ffff:ffff
36261b:dd:2300::/40261b:dd:23ff:ffff:ffff:ffff:ffff:ffff
37261b:dd:2400::/40261b:dd:24ff:ffff:ffff:ffff:ffff:ffff
38261b:dd:2500::/40261b:dd:25ff:ffff:ffff:ffff:ffff:ffff
39261b:dd:2600::/40261b:dd:26ff:ffff:ffff:ffff:ffff:ffff
40261b:dd:2700::/40261b:dd:27ff:ffff:ffff:ffff:ffff:ffff
41261b:dd:2800::/40261b:dd:28ff:ffff:ffff:ffff:ffff:ffff
42261b:dd:2900::/40261b:dd:29ff:ffff:ffff:ffff:ffff:ffff
43261b:dd:2a00::/40261b:dd:2aff:ffff:ffff:ffff:ffff:ffff
44261b:dd:2b00::/40261b:dd:2bff:ffff:ffff:ffff:ffff:ffff
45261b:dd:2c00::/40261b:dd:2cff:ffff:ffff:ffff:ffff:ffff
46261b:dd:2d00::/40261b:dd:2dff:ffff:ffff:ffff:ffff:ffff
47261b:dd:2e00::/40261b:dd:2eff:ffff:ffff:ffff:ffff:ffff
48261b:dd:2f00::/40261b:dd:2fff:ffff:ffff:ffff:ffff:ffff
49261b:dd:3000::/40261b:dd:30ff:ffff:ffff:ffff:ffff:ffff
50261b:dd:3100::/40261b:dd:31ff:ffff:ffff:ffff:ffff:ffff
51261b:dd:3200::/40261b:dd:32ff:ffff:ffff:ffff:ffff:ffff
52261b:dd:3300::/40261b:dd:33ff:ffff:ffff:ffff:ffff:ffff
53261b:dd:3400::/40261b:dd:34ff:ffff:ffff:ffff:ffff:ffff
54261b:dd:3500::/40261b:dd:35ff:ffff:ffff:ffff:ffff:ffff
55261b:dd:3600::/40261b:dd:36ff:ffff:ffff:ffff:ffff:ffff
56261b:dd:3700::/40261b:dd:37ff:ffff:ffff:ffff:ffff:ffff
57261b:dd:3800::/40261b:dd:38ff:ffff:ffff:ffff:ffff:ffff
58261b:dd:3900::/40261b:dd:39ff:ffff:ffff:ffff:ffff:ffff
59261b:dd:3a00::/40261b:dd:3aff:ffff:ffff:ffff:ffff:ffff
60261b:dd:3b00::/40261b:dd:3bff:ffff:ffff:ffff:ffff:ffff
61261b:dd:3c00::/40261b:dd:3cff:ffff:ffff:ffff:ffff:ffff
62261b:dd:3d00::/40261b:dd:3dff:ffff:ffff:ffff:ffff:ffff
63261b:dd:3e00::/40261b:dd:3eff:ffff:ffff:ffff:ffff:ffff
64261b:dd:3f00::/40261b:dd:3fff:ffff:ffff:ffff:ffff:ffff
65261b:dd:4000::/40261b:dd:40ff:ffff:ffff:ffff:ffff:ffff
66261b:dd:4100::/40261b:dd:41ff:ffff:ffff:ffff:ffff:ffff
67261b:dd:4200::/40261b:dd:42ff:ffff:ffff:ffff:ffff:ffff
68261b:dd:4300::/40261b:dd:43ff:ffff:ffff:ffff:ffff:ffff
69261b:dd:4400::/40261b:dd:44ff:ffff:ffff:ffff:ffff:ffff
70261b:dd:4500::/40261b:dd:45ff:ffff:ffff:ffff:ffff:ffff
71261b:dd:4600::/40261b:dd:46ff:ffff:ffff:ffff:ffff:ffff
72261b:dd:4700::/40261b:dd:47ff:ffff:ffff:ffff:ffff:ffff
73261b:dd:4800::/40261b:dd:48ff:ffff:ffff:ffff:ffff:ffff
74261b:dd:4900::/40261b:dd:49ff:ffff:ffff:ffff:ffff:ffff
75261b:dd:4a00::/40261b:dd:4aff:ffff:ffff:ffff:ffff:ffff
76261b:dd:4b00::/40261b:dd:4bff:ffff:ffff:ffff:ffff:ffff
77261b:dd:4c00::/40261b:dd:4cff:ffff:ffff:ffff:ffff:ffff
78261b:dd:4d00::/40261b:dd:4dff:ffff:ffff:ffff:ffff:ffff
79261b:dd:4e00::/40261b:dd:4eff:ffff:ffff:ffff:ffff:ffff
80261b:dd:4f00::/40261b:dd:4fff:ffff:ffff:ffff:ffff:ffff
81261b:dd:5000::/40261b:dd:50ff:ffff:ffff:ffff:ffff:ffff
82261b:dd:5100::/40261b:dd:51ff:ffff:ffff:ffff:ffff:ffff
83261b:dd:5200::/40261b:dd:52ff:ffff:ffff:ffff:ffff:ffff
84261b:dd:5300::/40261b:dd:53ff:ffff:ffff:ffff:ffff:ffff
85261b:dd:5400::/40261b:dd:54ff:ffff:ffff:ffff:ffff:ffff
86261b:dd:5500::/40261b:dd:55ff:ffff:ffff:ffff:ffff:ffff
87261b:dd:5600::/40261b:dd:56ff:ffff:ffff:ffff:ffff:ffff
88261b:dd:5700::/40261b:dd:57ff:ffff:ffff:ffff:ffff:ffff
89261b:dd:5800::/40261b:dd:58ff:ffff:ffff:ffff:ffff:ffff
90261b:dd:5900::/40261b:dd:59ff:ffff:ffff:ffff:ffff:ffff
91261b:dd:5a00::/40261b:dd:5aff:ffff:ffff:ffff:ffff:ffff
92261b:dd:5b00::/40261b:dd:5bff:ffff:ffff:ffff:ffff:ffff
93261b:dd:5c00::/40261b:dd:5cff:ffff:ffff:ffff:ffff:ffff
94261b:dd:5d00::/40261b:dd:5dff:ffff:ffff:ffff:ffff:ffff
95261b:dd:5e00::/40261b:dd:5eff:ffff:ffff:ffff:ffff:ffff
96261b:dd:5f00::/40261b:dd:5fff:ffff:ffff:ffff:ffff:ffff
97261b:dd:6000::/40261b:dd:60ff:ffff:ffff:ffff:ffff:ffff
98261b:dd:6100::/40261b:dd:61ff:ffff:ffff:ffff:ffff:ffff
99261b:dd:6200::/40261b:dd:62ff:ffff:ffff:ffff:ffff:ffff
100261b:dd:6300::/40261b:dd:63ff:ffff:ffff:ffff:ffff:ffff
101261b:dd:6400::/40261b:dd:64ff:ffff:ffff:ffff:ffff:ffff
102261b:dd:6500::/40261b:dd:65ff:ffff:ffff:ffff:ffff:ffff
103261b:dd:6600::/40261b:dd:66ff:ffff:ffff:ffff:ffff:ffff
104261b:dd:6700::/40261b:dd:67ff:ffff:ffff:ffff:ffff:ffff
105261b:dd:6800::/40261b:dd:68ff:ffff:ffff:ffff:ffff:ffff
106261b:dd:6900::/40261b:dd:69ff:ffff:ffff:ffff:ffff:ffff
107261b:dd:6a00::/40261b:dd:6aff:ffff:ffff:ffff:ffff:ffff
108261b:dd:6b00::/40261b:dd:6bff:ffff:ffff:ffff:ffff:ffff
109261b:dd:6c00::/40261b:dd:6cff:ffff:ffff:ffff:ffff:ffff
110261b:dd:6d00::/40261b:dd:6dff:ffff:ffff:ffff:ffff:ffff
111261b:dd:6e00::/40261b:dd:6eff:ffff:ffff:ffff:ffff:ffff
112261b:dd:6f00::/40261b:dd:6fff:ffff:ffff:ffff:ffff:ffff
113261b:dd:7000::/40261b:dd:70ff:ffff:ffff:ffff:ffff:ffff
114261b:dd:7100::/40261b:dd:71ff:ffff:ffff:ffff:ffff:ffff
115261b:dd:7200::/40261b:dd:72ff:ffff:ffff:ffff:ffff:ffff
116261b:dd:7300::/40261b:dd:73ff:ffff:ffff:ffff:ffff:ffff
117261b:dd:7400::/40261b:dd:74ff:ffff:ffff:ffff:ffff:ffff
118261b:dd:7500::/40261b:dd:75ff:ffff:ffff:ffff:ffff:ffff
119261b:dd:7600::/40261b:dd:76ff:ffff:ffff:ffff:ffff:ffff
120261b:dd:7700::/40261b:dd:77ff:ffff:ffff:ffff:ffff:ffff
121261b:dd:7800::/40261b:dd:78ff:ffff:ffff:ffff:ffff:ffff
122261b:dd:7900::/40261b:dd:79ff:ffff:ffff:ffff:ffff:ffff
123261b:dd:7a00::/40261b:dd:7aff:ffff:ffff:ffff:ffff:ffff
124261b:dd:7b00::/40261b:dd:7bff:ffff:ffff:ffff:ffff:ffff
125261b:dd:7c00::/40261b:dd:7cff:ffff:ffff:ffff:ffff:ffff
126261b:dd:7d00::/40261b:dd:7dff:ffff:ffff:ffff:ffff:ffff
127261b:dd:7e00::/40261b:dd:7eff:ffff:ffff:ffff:ffff:ffff
128261b:dd:7f00::/40261b:dd:7fff:ffff:ffff:ffff:ffff:ffff
129261b:dd:8000::/40261b:dd:80ff:ffff:ffff:ffff:ffff:ffff
130261b:dd:8100::/40261b:dd:81ff:ffff:ffff:ffff:ffff:ffff
131261b:dd:8200::/40261b:dd:82ff:ffff:ffff:ffff:ffff:ffff
132261b:dd:8300::/40261b:dd:83ff:ffff:ffff:ffff:ffff:ffff
133261b:dd:8400::/40261b:dd:84ff:ffff:ffff:ffff:ffff:ffff
134261b:dd:8500::/40261b:dd:85ff:ffff:ffff:ffff:ffff:ffff
135261b:dd:8600::/40261b:dd:86ff:ffff:ffff:ffff:ffff:ffff
136261b:dd:8700::/40261b:dd:87ff:ffff:ffff:ffff:ffff:ffff
137261b:dd:8800::/40261b:dd:88ff:ffff:ffff:ffff:ffff:ffff
138261b:dd:8900::/40261b:dd:89ff:ffff:ffff:ffff:ffff:ffff
139261b:dd:8a00::/40261b:dd:8aff:ffff:ffff:ffff:ffff:ffff
140261b:dd:8b00::/40261b:dd:8bff:ffff:ffff:ffff:ffff:ffff
141261b:dd:8c00::/40261b:dd:8cff:ffff:ffff:ffff:ffff:ffff
142261b:dd:8d00::/40261b:dd:8dff:ffff:ffff:ffff:ffff:ffff
143261b:dd:8e00::/40261b:dd:8eff:ffff:ffff:ffff:ffff:ffff
144261b:dd:8f00::/40261b:dd:8fff:ffff:ffff:ffff:ffff:ffff
145261b:dd:9000::/40261b:dd:90ff:ffff:ffff:ffff:ffff:ffff
146261b:dd:9100::/40261b:dd:91ff:ffff:ffff:ffff:ffff:ffff
147261b:dd:9200::/40261b:dd:92ff:ffff:ffff:ffff:ffff:ffff
148261b:dd:9300::/40261b:dd:93ff:ffff:ffff:ffff:ffff:ffff
149261b:dd:9400::/40261b:dd:94ff:ffff:ffff:ffff:ffff:ffff
150261b:dd:9500::/40261b:dd:95ff:ffff:ffff:ffff:ffff:ffff
151261b:dd:9600::/40261b:dd:96ff:ffff:ffff:ffff:ffff:ffff
152261b:dd:9700::/40261b:dd:97ff:ffff:ffff:ffff:ffff:ffff
153261b:dd:9800::/40261b:dd:98ff:ffff:ffff:ffff:ffff:ffff
154261b:dd:9900::/40261b:dd:99ff:ffff:ffff:ffff:ffff:ffff
155261b:dd:9a00::/40261b:dd:9aff:ffff:ffff:ffff:ffff:ffff
156261b:dd:9b00::/40261b:dd:9bff:ffff:ffff:ffff:ffff:ffff
157261b:dd:9c00::/40261b:dd:9cff:ffff:ffff:ffff:ffff:ffff
158261b:dd:9d00::/40261b:dd:9dff:ffff:ffff:ffff:ffff:ffff
159261b:dd:9e00::/40261b:dd:9eff:ffff:ffff:ffff:ffff:ffff
160261b:dd:9f00::/40261b:dd:9fff:ffff:ffff:ffff:ffff:ffff
161261b:dd:a000::/40261b:dd:a0ff:ffff:ffff:ffff:ffff:ffff
162261b:dd:a100::/40261b:dd:a1ff:ffff:ffff:ffff:ffff:ffff
163261b:dd:a200::/40261b:dd:a2ff:ffff:ffff:ffff:ffff:ffff
164261b:dd:a300::/40261b:dd:a3ff:ffff:ffff:ffff:ffff:ffff
165261b:dd:a400::/40261b:dd:a4ff:ffff:ffff:ffff:ffff:ffff
166261b:dd:a500::/40261b:dd:a5ff:ffff:ffff:ffff:ffff:ffff
167261b:dd:a600::/40261b:dd:a6ff:ffff:ffff:ffff:ffff:ffff
168261b:dd:a700::/40261b:dd:a7ff:ffff:ffff:ffff:ffff:ffff
169261b:dd:a800::/40261b:dd:a8ff:ffff:ffff:ffff:ffff:ffff
170261b:dd:a900::/40261b:dd:a9ff:ffff:ffff:ffff:ffff:ffff
171261b:dd:aa00::/40261b:dd:aaff:ffff:ffff:ffff:ffff:ffff
172261b:dd:ab00::/40261b:dd:abff:ffff:ffff:ffff:ffff:ffff
173261b:dd:ac00::/40261b:dd:acff:ffff:ffff:ffff:ffff:ffff
174261b:dd:ad00::/40261b:dd:adff:ffff:ffff:ffff:ffff:ffff
175261b:dd:ae00::/40261b:dd:aeff:ffff:ffff:ffff:ffff:ffff
176261b:dd:af00::/40261b:dd:afff:ffff:ffff:ffff:ffff:ffff
177261b:dd:b000::/40261b:dd:b0ff:ffff:ffff:ffff:ffff:ffff
178261b:dd:b100::/40261b:dd:b1ff:ffff:ffff:ffff:ffff:ffff
179261b:dd:b200::/40261b:dd:b2ff:ffff:ffff:ffff:ffff:ffff
180261b:dd:b300::/40261b:dd:b3ff:ffff:ffff:ffff:ffff:ffff
181261b:dd:b400::/40261b:dd:b4ff:ffff:ffff:ffff:ffff:ffff
182261b:dd:b500::/40261b:dd:b5ff:ffff:ffff:ffff:ffff:ffff
183261b:dd:b600::/40261b:dd:b6ff:ffff:ffff:ffff:ffff:ffff
184261b:dd:b700::/40261b:dd:b7ff:ffff:ffff:ffff:ffff:ffff
185261b:dd:b800::/40261b:dd:b8ff:ffff:ffff:ffff:ffff:ffff
186261b:dd:b900::/40261b:dd:b9ff:ffff:ffff:ffff:ffff:ffff
187261b:dd:ba00::/40261b:dd:baff:ffff:ffff:ffff:ffff:ffff
188261b:dd:bb00::/40261b:dd:bbff:ffff:ffff:ffff:ffff:ffff
189261b:dd:bc00::/40261b:dd:bcff:ffff:ffff:ffff:ffff:ffff
190261b:dd:bd00::/40261b:dd:bdff:ffff:ffff:ffff:ffff:ffff
191261b:dd:be00::/40261b:dd:beff:ffff:ffff:ffff:ffff:ffff
192261b:dd:bf00::/40261b:dd:bfff:ffff:ffff:ffff:ffff:ffff
193261b:dd:c000::/40261b:dd:c0ff:ffff:ffff:ffff:ffff:ffff
194261b:dd:c100::/40261b:dd:c1ff:ffff:ffff:ffff:ffff:ffff
195261b:dd:c200::/40261b:dd:c2ff:ffff:ffff:ffff:ffff:ffff
196261b:dd:c300::/40261b:dd:c3ff:ffff:ffff:ffff:ffff:ffff
197261b:dd:c400::/40261b:dd:c4ff:ffff:ffff:ffff:ffff:ffff
198261b:dd:c500::/40261b:dd:c5ff:ffff:ffff:ffff:ffff:ffff
199261b:dd:c600::/40261b:dd:c6ff:ffff:ffff:ffff:ffff:ffff
200261b:dd:c700::/40261b:dd:c7ff:ffff:ffff:ffff:ffff:ffff
201261b:dd:c800::/40261b:dd:c8ff:ffff:ffff:ffff:ffff:ffff
202261b:dd:c900::/40261b:dd:c9ff:ffff:ffff:ffff:ffff:ffff
203261b:dd:ca00::/40261b:dd:caff:ffff:ffff:ffff:ffff:ffff
204261b:dd:cb00::/40261b:dd:cbff:ffff:ffff:ffff:ffff:ffff
205261b:dd:cc00::/40261b:dd:ccff:ffff:ffff:ffff:ffff:ffff
206261b:dd:cd00::/40261b:dd:cdff:ffff:ffff:ffff:ffff:ffff
207261b:dd:ce00::/40261b:dd:ceff:ffff:ffff:ffff:ffff:ffff
208261b:dd:cf00::/40261b:dd:cfff:ffff:ffff:ffff:ffff:ffff
209261b:dd:d000::/40261b:dd:d0ff:ffff:ffff:ffff:ffff:ffff
210261b:dd:d100::/40261b:dd:d1ff:ffff:ffff:ffff:ffff:ffff
211261b:dd:d200::/40261b:dd:d2ff:ffff:ffff:ffff:ffff:ffff
212261b:dd:d300::/40261b:dd:d3ff:ffff:ffff:ffff:ffff:ffff
213261b:dd:d400::/40261b:dd:d4ff:ffff:ffff:ffff:ffff:ffff
214261b:dd:d500::/40261b:dd:d5ff:ffff:ffff:ffff:ffff:ffff
215261b:dd:d600::/40261b:dd:d6ff:ffff:ffff:ffff:ffff:ffff
216261b:dd:d700::/40261b:dd:d7ff:ffff:ffff:ffff:ffff:ffff
217261b:dd:d800::/40261b:dd:d8ff:ffff:ffff:ffff:ffff:ffff
218261b:dd:d900::/40261b:dd:d9ff:ffff:ffff:ffff:ffff:ffff
219261b:dd:da00::/40261b:dd:daff:ffff:ffff:ffff:ffff:ffff
220261b:dd:db00::/40261b:dd:dbff:ffff:ffff:ffff:ffff:ffff
221261b:dd:dc00::/40261b:dd:dcff:ffff:ffff:ffff:ffff:ffff
222261b:dd:dd00::/40261b:dd:ddff:ffff:ffff:ffff:ffff:ffff
223261b:dd:de00::/40261b:dd:deff:ffff:ffff:ffff:ffff:ffff
224261b:dd:df00::/40261b:dd:dfff:ffff:ffff:ffff:ffff:ffff
225261b:dd:e000::/40261b:dd:e0ff:ffff:ffff:ffff:ffff:ffff
226261b:dd:e100::/40261b:dd:e1ff:ffff:ffff:ffff:ffff:ffff
227261b:dd:e200::/40261b:dd:e2ff:ffff:ffff:ffff:ffff:ffff
228261b:dd:e300::/40261b:dd:e3ff:ffff:ffff:ffff:ffff:ffff
229261b:dd:e400::/40261b:dd:e4ff:ffff:ffff:ffff:ffff:ffff
230261b:dd:e500::/40261b:dd:e5ff:ffff:ffff:ffff:ffff:ffff
231261b:dd:e600::/40261b:dd:e6ff:ffff:ffff:ffff:ffff:ffff
232261b:dd:e700::/40261b:dd:e7ff:ffff:ffff:ffff:ffff:ffff
233261b:dd:e800::/40261b:dd:e8ff:ffff:ffff:ffff:ffff:ffff
234261b:dd:e900::/40261b:dd:e9ff:ffff:ffff:ffff:ffff:ffff
235261b:dd:ea00::/40261b:dd:eaff:ffff:ffff:ffff:ffff:ffff
236261b:dd:eb00::/40261b:dd:ebff:ffff:ffff:ffff:ffff:ffff
237261b:dd:ec00::/40261b:dd:ecff:ffff:ffff:ffff:ffff:ffff
238261b:dd:ed00::/40261b:dd:edff:ffff:ffff:ffff:ffff:ffff
239261b:dd:ee00::/40261b:dd:eeff:ffff:ffff:ffff:ffff:ffff
240261b:dd:ef00::/40261b:dd:efff:ffff:ffff:ffff:ffff:ffff
241261b:dd:f000::/40261b:dd:f0ff:ffff:ffff:ffff:ffff:ffff
242261b:dd:f100::/40261b:dd:f1ff:ffff:ffff:ffff:ffff:ffff
243261b:dd:f200::/40261b:dd:f2ff:ffff:ffff:ffff:ffff:ffff
244261b:dd:f300::/40261b:dd:f3ff:ffff:ffff:ffff:ffff:ffff
245261b:dd:f400::/40261b:dd:f4ff:ffff:ffff:ffff:ffff:ffff
246261b:dd:f500::/40261b:dd:f5ff:ffff:ffff:ffff:ffff:ffff
247261b:dd:f600::/40261b:dd:f6ff:ffff:ffff:ffff:ffff:ffff
248261b:dd:f700::/40261b:dd:f7ff:ffff:ffff:ffff:ffff:ffff
249261b:dd:f800::/40261b:dd:f8ff:ffff:ffff:ffff:ffff:ffff
250261b:dd:f900::/40261b:dd:f9ff:ffff:ffff:ffff:ffff:ffff
251261b:dd:fa00::/40261b:dd:faff:ffff:ffff:ffff:ffff:ffff
252261b:dd:fb00::/40261b:dd:fbff:ffff:ffff:ffff:ffff:ffff
253261b:dd:fc00::/40261b:dd:fcff:ffff:ffff:ffff:ffff:ffff
254261b:dd:fd00::/40261b:dd:fdff:ffff:ffff:ffff:ffff:ffff
255261b:dd:fe00::/40261b:dd:feff:ffff:ffff:ffff:ffff:ffff
256261b:dd:ff00::/40261b:dd: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.