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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
321b::/16
First address
321b::
Last address
321b: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
321b:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
b.1.2.3.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

321b::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1321b::/24321b:ff:ffff:ffff:ffff:ffff:ffff:ffff
2321b:100::/24321b:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3321b:200::/24321b:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4321b:300::/24321b:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5321b:400::/24321b:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6321b:500::/24321b:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7321b:600::/24321b:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8321b:700::/24321b:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9321b:800::/24321b:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10321b:900::/24321b:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11321b:a00::/24321b:aff:ffff:ffff:ffff:ffff:ffff:ffff
12321b:b00::/24321b:bff:ffff:ffff:ffff:ffff:ffff:ffff
13321b:c00::/24321b:cff:ffff:ffff:ffff:ffff:ffff:ffff
14321b:d00::/24321b:dff:ffff:ffff:ffff:ffff:ffff:ffff
15321b:e00::/24321b:eff:ffff:ffff:ffff:ffff:ffff:ffff
16321b:f00::/24321b:fff:ffff:ffff:ffff:ffff:ffff:ffff
17321b:1000::/24321b:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18321b:1100::/24321b:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19321b:1200::/24321b:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20321b:1300::/24321b:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21321b:1400::/24321b:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22321b:1500::/24321b:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23321b:1600::/24321b:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24321b:1700::/24321b:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25321b:1800::/24321b:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26321b:1900::/24321b:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27321b:1a00::/24321b:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28321b:1b00::/24321b:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29321b:1c00::/24321b:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30321b:1d00::/24321b:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31321b:1e00::/24321b:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32321b:1f00::/24321b:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33321b:2000::/24321b:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34321b:2100::/24321b:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35321b:2200::/24321b:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36321b:2300::/24321b:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37321b:2400::/24321b:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38321b:2500::/24321b:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39321b:2600::/24321b:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40321b:2700::/24321b:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41321b:2800::/24321b:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42321b:2900::/24321b:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43321b:2a00::/24321b:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44321b:2b00::/24321b:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45321b:2c00::/24321b:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46321b:2d00::/24321b:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47321b:2e00::/24321b:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48321b:2f00::/24321b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49321b:3000::/24321b:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50321b:3100::/24321b:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51321b:3200::/24321b:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52321b:3300::/24321b:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53321b:3400::/24321b:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54321b:3500::/24321b:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55321b:3600::/24321b:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56321b:3700::/24321b:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57321b:3800::/24321b:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58321b:3900::/24321b:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59321b:3a00::/24321b:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60321b:3b00::/24321b:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61321b:3c00::/24321b:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62321b:3d00::/24321b:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63321b:3e00::/24321b:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64321b:3f00::/24321b:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65321b:4000::/24321b:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66321b:4100::/24321b:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67321b:4200::/24321b:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68321b:4300::/24321b:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69321b:4400::/24321b:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70321b:4500::/24321b:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71321b:4600::/24321b:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72321b:4700::/24321b:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73321b:4800::/24321b:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74321b:4900::/24321b:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75321b:4a00::/24321b:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76321b:4b00::/24321b:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77321b:4c00::/24321b:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78321b:4d00::/24321b:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79321b:4e00::/24321b:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80321b:4f00::/24321b:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81321b:5000::/24321b:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82321b:5100::/24321b:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83321b:5200::/24321b:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84321b:5300::/24321b:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85321b:5400::/24321b:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86321b:5500::/24321b:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87321b:5600::/24321b:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88321b:5700::/24321b:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89321b:5800::/24321b:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90321b:5900::/24321b:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91321b:5a00::/24321b:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92321b:5b00::/24321b:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93321b:5c00::/24321b:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94321b:5d00::/24321b:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95321b:5e00::/24321b:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96321b:5f00::/24321b:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97321b:6000::/24321b:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98321b:6100::/24321b:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99321b:6200::/24321b:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100321b:6300::/24321b:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101321b:6400::/24321b:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102321b:6500::/24321b:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103321b:6600::/24321b:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104321b:6700::/24321b:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105321b:6800::/24321b:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106321b:6900::/24321b:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107321b:6a00::/24321b:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108321b:6b00::/24321b:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109321b:6c00::/24321b:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110321b:6d00::/24321b:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111321b:6e00::/24321b:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112321b:6f00::/24321b:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113321b:7000::/24321b:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114321b:7100::/24321b:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115321b:7200::/24321b:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116321b:7300::/24321b:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117321b:7400::/24321b:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118321b:7500::/24321b:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119321b:7600::/24321b:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120321b:7700::/24321b:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121321b:7800::/24321b:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122321b:7900::/24321b:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123321b:7a00::/24321b:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124321b:7b00::/24321b:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125321b:7c00::/24321b:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126321b:7d00::/24321b:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127321b:7e00::/24321b:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128321b:7f00::/24321b:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129321b:8000::/24321b:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130321b:8100::/24321b:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131321b:8200::/24321b:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132321b:8300::/24321b:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133321b:8400::/24321b:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134321b:8500::/24321b:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135321b:8600::/24321b:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136321b:8700::/24321b:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137321b:8800::/24321b:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138321b:8900::/24321b:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139321b:8a00::/24321b:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140321b:8b00::/24321b:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141321b:8c00::/24321b:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142321b:8d00::/24321b:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143321b:8e00::/24321b:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144321b:8f00::/24321b:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145321b:9000::/24321b:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146321b:9100::/24321b:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147321b:9200::/24321b:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148321b:9300::/24321b:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149321b:9400::/24321b:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150321b:9500::/24321b:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151321b:9600::/24321b:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152321b:9700::/24321b:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153321b:9800::/24321b:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154321b:9900::/24321b:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155321b:9a00::/24321b:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156321b:9b00::/24321b:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157321b:9c00::/24321b:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158321b:9d00::/24321b:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159321b:9e00::/24321b:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160321b:9f00::/24321b:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161321b:a000::/24321b:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162321b:a100::/24321b:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163321b:a200::/24321b:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164321b:a300::/24321b:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165321b:a400::/24321b:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166321b:a500::/24321b:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167321b:a600::/24321b:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168321b:a700::/24321b:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169321b:a800::/24321b:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170321b:a900::/24321b:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171321b:aa00::/24321b:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172321b:ab00::/24321b:abff:ffff:ffff:ffff:ffff:ffff:ffff
173321b:ac00::/24321b:acff:ffff:ffff:ffff:ffff:ffff:ffff
174321b:ad00::/24321b:adff:ffff:ffff:ffff:ffff:ffff:ffff
175321b:ae00::/24321b:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176321b:af00::/24321b:afff:ffff:ffff:ffff:ffff:ffff:ffff
177321b:b000::/24321b:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178321b:b100::/24321b:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179321b:b200::/24321b:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180321b:b300::/24321b:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181321b:b400::/24321b:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182321b:b500::/24321b:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183321b:b600::/24321b:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184321b:b700::/24321b:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185321b:b800::/24321b:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186321b:b900::/24321b:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187321b:ba00::/24321b:baff:ffff:ffff:ffff:ffff:ffff:ffff
188321b:bb00::/24321b:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189321b:bc00::/24321b:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190321b:bd00::/24321b:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191321b:be00::/24321b:beff:ffff:ffff:ffff:ffff:ffff:ffff
192321b:bf00::/24321b:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193321b:c000::/24321b:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194321b:c100::/24321b:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195321b:c200::/24321b:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196321b:c300::/24321b:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197321b:c400::/24321b:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198321b:c500::/24321b:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199321b:c600::/24321b:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200321b:c700::/24321b:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201321b:c800::/24321b:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202321b:c900::/24321b:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203321b:ca00::/24321b:caff:ffff:ffff:ffff:ffff:ffff:ffff
204321b:cb00::/24321b:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205321b:cc00::/24321b:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206321b:cd00::/24321b:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207321b:ce00::/24321b:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208321b:cf00::/24321b:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209321b:d000::/24321b:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210321b:d100::/24321b:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211321b:d200::/24321b:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212321b:d300::/24321b:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213321b:d400::/24321b:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214321b:d500::/24321b:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215321b:d600::/24321b:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216321b:d700::/24321b:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217321b:d800::/24321b:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218321b:d900::/24321b:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219321b:da00::/24321b:daff:ffff:ffff:ffff:ffff:ffff:ffff
220321b:db00::/24321b:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221321b:dc00::/24321b:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222321b:dd00::/24321b:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223321b:de00::/24321b:deff:ffff:ffff:ffff:ffff:ffff:ffff
224321b:df00::/24321b:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225321b:e000::/24321b:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226321b:e100::/24321b:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227321b:e200::/24321b:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228321b:e300::/24321b:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229321b:e400::/24321b:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230321b:e500::/24321b:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231321b:e600::/24321b:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232321b:e700::/24321b:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233321b:e800::/24321b:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234321b:e900::/24321b:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235321b:ea00::/24321b:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236321b:eb00::/24321b:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237321b:ec00::/24321b:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238321b:ed00::/24321b:edff:ffff:ffff:ffff:ffff:ffff:ffff
239321b:ee00::/24321b:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240321b:ef00::/24321b:efff:ffff:ffff:ffff:ffff:ffff:ffff
241321b:f000::/24321b:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242321b:f100::/24321b:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243321b:f200::/24321b:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244321b:f300::/24321b:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245321b:f400::/24321b:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246321b:f500::/24321b:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247321b:f600::/24321b:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248321b:f700::/24321b:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249321b:f800::/24321b:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250321b:f900::/24321b:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251321b:fa00::/24321b:faff:ffff:ffff:ffff:ffff:ffff:ffff
252321b:fb00::/24321b:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253321b:fc00::/24321b:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254321b:fd00::/24321b:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255321b:fe00::/24321b:feff:ffff:ffff:ffff:ffff:ffff:ffff
256321b:ff00::/24321b: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.