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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.

Network201.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
201.0.0.0
Broadcast address
201.255.255.255
First usable
201.0.0.1
Last usable
201.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
C (default /24)
As numbers
Hex C9000000 · Integer 3372220416 to 3388997631
Reverse DNS zone
201.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001001..00000000.00000000.00000000201.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11001001..00000000.00000000.00000000201.0.0.0
Broadcast11001001..11111111.11111111.11111111201.255.255.255
Split into smaller subnets/20
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

201.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1201.0.0.0/20201.0.0.1 to 201.0.15.254201.0.15.2554,094
2201.0.16.0/20201.0.16.1 to 201.0.31.254201.0.31.2554,094
3201.0.32.0/20201.0.32.1 to 201.0.47.254201.0.47.2554,094
4201.0.48.0/20201.0.48.1 to 201.0.63.254201.0.63.2554,094
5201.0.64.0/20201.0.64.1 to 201.0.79.254201.0.79.2554,094
6201.0.80.0/20201.0.80.1 to 201.0.95.254201.0.95.2554,094
7201.0.96.0/20201.0.96.1 to 201.0.111.254201.0.111.2554,094
8201.0.112.0/20201.0.112.1 to 201.0.127.254201.0.127.2554,094
9201.0.128.0/20201.0.128.1 to 201.0.143.254201.0.143.2554,094
10201.0.144.0/20201.0.144.1 to 201.0.159.254201.0.159.2554,094
11201.0.160.0/20201.0.160.1 to 201.0.175.254201.0.175.2554,094
12201.0.176.0/20201.0.176.1 to 201.0.191.254201.0.191.2554,094
13201.0.192.0/20201.0.192.1 to 201.0.207.254201.0.207.2554,094
14201.0.208.0/20201.0.208.1 to 201.0.223.254201.0.223.2554,094
15201.0.224.0/20201.0.224.1 to 201.0.239.254201.0.239.2554,094
16201.0.240.0/20201.0.240.1 to 201.0.255.254201.0.255.2554,094
17201.1.0.0/20201.1.0.1 to 201.1.15.254201.1.15.2554,094
18201.1.16.0/20201.1.16.1 to 201.1.31.254201.1.31.2554,094
19201.1.32.0/20201.1.32.1 to 201.1.47.254201.1.47.2554,094
20201.1.48.0/20201.1.48.1 to 201.1.63.254201.1.63.2554,094
21201.1.64.0/20201.1.64.1 to 201.1.79.254201.1.79.2554,094
22201.1.80.0/20201.1.80.1 to 201.1.95.254201.1.95.2554,094
23201.1.96.0/20201.1.96.1 to 201.1.111.254201.1.111.2554,094
24201.1.112.0/20201.1.112.1 to 201.1.127.254201.1.127.2554,094
25201.1.128.0/20201.1.128.1 to 201.1.143.254201.1.143.2554,094
26201.1.144.0/20201.1.144.1 to 201.1.159.254201.1.159.2554,094
27201.1.160.0/20201.1.160.1 to 201.1.175.254201.1.175.2554,094
28201.1.176.0/20201.1.176.1 to 201.1.191.254201.1.191.2554,094
29201.1.192.0/20201.1.192.1 to 201.1.207.254201.1.207.2554,094
30201.1.208.0/20201.1.208.1 to 201.1.223.254201.1.223.2554,094
31201.1.224.0/20201.1.224.1 to 201.1.239.254201.1.239.2554,094
32201.1.240.0/20201.1.240.1 to 201.1.255.254201.1.255.2554,094
33201.2.0.0/20201.2.0.1 to 201.2.15.254201.2.15.2554,094
34201.2.16.0/20201.2.16.1 to 201.2.31.254201.2.31.2554,094
35201.2.32.0/20201.2.32.1 to 201.2.47.254201.2.47.2554,094
36201.2.48.0/20201.2.48.1 to 201.2.63.254201.2.63.2554,094
37201.2.64.0/20201.2.64.1 to 201.2.79.254201.2.79.2554,094
38201.2.80.0/20201.2.80.1 to 201.2.95.254201.2.95.2554,094
39201.2.96.0/20201.2.96.1 to 201.2.111.254201.2.111.2554,094
40201.2.112.0/20201.2.112.1 to 201.2.127.254201.2.127.2554,094
41201.2.128.0/20201.2.128.1 to 201.2.143.254201.2.143.2554,094
42201.2.144.0/20201.2.144.1 to 201.2.159.254201.2.159.2554,094
43201.2.160.0/20201.2.160.1 to 201.2.175.254201.2.175.2554,094
44201.2.176.0/20201.2.176.1 to 201.2.191.254201.2.191.2554,094
45201.2.192.0/20201.2.192.1 to 201.2.207.254201.2.207.2554,094
46201.2.208.0/20201.2.208.1 to 201.2.223.254201.2.223.2554,094
47201.2.224.0/20201.2.224.1 to 201.2.239.254201.2.239.2554,094
48201.2.240.0/20201.2.240.1 to 201.2.255.254201.2.255.2554,094
49201.3.0.0/20201.3.0.1 to 201.3.15.254201.3.15.2554,094
50201.3.16.0/20201.3.16.1 to 201.3.31.254201.3.31.2554,094
51201.3.32.0/20201.3.32.1 to 201.3.47.254201.3.47.2554,094
52201.3.48.0/20201.3.48.1 to 201.3.63.254201.3.63.2554,094
53201.3.64.0/20201.3.64.1 to 201.3.79.254201.3.79.2554,094
54201.3.80.0/20201.3.80.1 to 201.3.95.254201.3.95.2554,094
55201.3.96.0/20201.3.96.1 to 201.3.111.254201.3.111.2554,094
56201.3.112.0/20201.3.112.1 to 201.3.127.254201.3.127.2554,094
57201.3.128.0/20201.3.128.1 to 201.3.143.254201.3.143.2554,094
58201.3.144.0/20201.3.144.1 to 201.3.159.254201.3.159.2554,094
59201.3.160.0/20201.3.160.1 to 201.3.175.254201.3.175.2554,094
60201.3.176.0/20201.3.176.1 to 201.3.191.254201.3.191.2554,094
61201.3.192.0/20201.3.192.1 to 201.3.207.254201.3.207.2554,094
62201.3.208.0/20201.3.208.1 to 201.3.223.254201.3.223.2554,094
63201.3.224.0/20201.3.224.1 to 201.3.239.254201.3.239.2554,094
64201.3.240.0/20201.3.240.1 to 201.3.255.254201.3.255.2554,094
65201.4.0.0/20201.4.0.1 to 201.4.15.254201.4.15.2554,094
66201.4.16.0/20201.4.16.1 to 201.4.31.254201.4.31.2554,094
67201.4.32.0/20201.4.32.1 to 201.4.47.254201.4.47.2554,094
68201.4.48.0/20201.4.48.1 to 201.4.63.254201.4.63.2554,094
69201.4.64.0/20201.4.64.1 to 201.4.79.254201.4.79.2554,094
70201.4.80.0/20201.4.80.1 to 201.4.95.254201.4.95.2554,094
71201.4.96.0/20201.4.96.1 to 201.4.111.254201.4.111.2554,094
72201.4.112.0/20201.4.112.1 to 201.4.127.254201.4.127.2554,094
73201.4.128.0/20201.4.128.1 to 201.4.143.254201.4.143.2554,094
74201.4.144.0/20201.4.144.1 to 201.4.159.254201.4.159.2554,094
75201.4.160.0/20201.4.160.1 to 201.4.175.254201.4.175.2554,094
76201.4.176.0/20201.4.176.1 to 201.4.191.254201.4.191.2554,094
77201.4.192.0/20201.4.192.1 to 201.4.207.254201.4.207.2554,094
78201.4.208.0/20201.4.208.1 to 201.4.223.254201.4.223.2554,094
79201.4.224.0/20201.4.224.1 to 201.4.239.254201.4.239.2554,094
80201.4.240.0/20201.4.240.1 to 201.4.255.254201.4.255.2554,094
81201.5.0.0/20201.5.0.1 to 201.5.15.254201.5.15.2554,094
82201.5.16.0/20201.5.16.1 to 201.5.31.254201.5.31.2554,094
83201.5.32.0/20201.5.32.1 to 201.5.47.254201.5.47.2554,094
84201.5.48.0/20201.5.48.1 to 201.5.63.254201.5.63.2554,094
85201.5.64.0/20201.5.64.1 to 201.5.79.254201.5.79.2554,094
86201.5.80.0/20201.5.80.1 to 201.5.95.254201.5.95.2554,094
87201.5.96.0/20201.5.96.1 to 201.5.111.254201.5.111.2554,094
88201.5.112.0/20201.5.112.1 to 201.5.127.254201.5.127.2554,094
89201.5.128.0/20201.5.128.1 to 201.5.143.254201.5.143.2554,094
90201.5.144.0/20201.5.144.1 to 201.5.159.254201.5.159.2554,094
91201.5.160.0/20201.5.160.1 to 201.5.175.254201.5.175.2554,094
92201.5.176.0/20201.5.176.1 to 201.5.191.254201.5.191.2554,094
93201.5.192.0/20201.5.192.1 to 201.5.207.254201.5.207.2554,094
94201.5.208.0/20201.5.208.1 to 201.5.223.254201.5.223.2554,094
95201.5.224.0/20201.5.224.1 to 201.5.239.254201.5.239.2554,094
96201.5.240.0/20201.5.240.1 to 201.5.255.254201.5.255.2554,094
97201.6.0.0/20201.6.0.1 to 201.6.15.254201.6.15.2554,094
98201.6.16.0/20201.6.16.1 to 201.6.31.254201.6.31.2554,094
99201.6.32.0/20201.6.32.1 to 201.6.47.254201.6.47.2554,094
100201.6.48.0/20201.6.48.1 to 201.6.63.254201.6.63.2554,094
101201.6.64.0/20201.6.64.1 to 201.6.79.254201.6.79.2554,094
102201.6.80.0/20201.6.80.1 to 201.6.95.254201.6.95.2554,094
103201.6.96.0/20201.6.96.1 to 201.6.111.254201.6.111.2554,094
104201.6.112.0/20201.6.112.1 to 201.6.127.254201.6.127.2554,094
105201.6.128.0/20201.6.128.1 to 201.6.143.254201.6.143.2554,094
106201.6.144.0/20201.6.144.1 to 201.6.159.254201.6.159.2554,094
107201.6.160.0/20201.6.160.1 to 201.6.175.254201.6.175.2554,094
108201.6.176.0/20201.6.176.1 to 201.6.191.254201.6.191.2554,094
109201.6.192.0/20201.6.192.1 to 201.6.207.254201.6.207.2554,094
110201.6.208.0/20201.6.208.1 to 201.6.223.254201.6.223.2554,094
111201.6.224.0/20201.6.224.1 to 201.6.239.254201.6.239.2554,094
112201.6.240.0/20201.6.240.1 to 201.6.255.254201.6.255.2554,094
113201.7.0.0/20201.7.0.1 to 201.7.15.254201.7.15.2554,094
114201.7.16.0/20201.7.16.1 to 201.7.31.254201.7.31.2554,094
115201.7.32.0/20201.7.32.1 to 201.7.47.254201.7.47.2554,094
116201.7.48.0/20201.7.48.1 to 201.7.63.254201.7.63.2554,094
117201.7.64.0/20201.7.64.1 to 201.7.79.254201.7.79.2554,094
118201.7.80.0/20201.7.80.1 to 201.7.95.254201.7.95.2554,094
119201.7.96.0/20201.7.96.1 to 201.7.111.254201.7.111.2554,094
120201.7.112.0/20201.7.112.1 to 201.7.127.254201.7.127.2554,094
121201.7.128.0/20201.7.128.1 to 201.7.143.254201.7.143.2554,094
122201.7.144.0/20201.7.144.1 to 201.7.159.254201.7.159.2554,094
123201.7.160.0/20201.7.160.1 to 201.7.175.254201.7.175.2554,094
124201.7.176.0/20201.7.176.1 to 201.7.191.254201.7.191.2554,094
125201.7.192.0/20201.7.192.1 to 201.7.207.254201.7.207.2554,094
126201.7.208.0/20201.7.208.1 to 201.7.223.254201.7.223.2554,094
127201.7.224.0/20201.7.224.1 to 201.7.239.254201.7.239.2554,094
128201.7.240.0/20201.7.240.1 to 201.7.255.254201.7.255.2554,094
129201.8.0.0/20201.8.0.1 to 201.8.15.254201.8.15.2554,094
130201.8.16.0/20201.8.16.1 to 201.8.31.254201.8.31.2554,094
131201.8.32.0/20201.8.32.1 to 201.8.47.254201.8.47.2554,094
132201.8.48.0/20201.8.48.1 to 201.8.63.254201.8.63.2554,094
133201.8.64.0/20201.8.64.1 to 201.8.79.254201.8.79.2554,094
134201.8.80.0/20201.8.80.1 to 201.8.95.254201.8.95.2554,094
135201.8.96.0/20201.8.96.1 to 201.8.111.254201.8.111.2554,094
136201.8.112.0/20201.8.112.1 to 201.8.127.254201.8.127.2554,094
137201.8.128.0/20201.8.128.1 to 201.8.143.254201.8.143.2554,094
138201.8.144.0/20201.8.144.1 to 201.8.159.254201.8.159.2554,094
139201.8.160.0/20201.8.160.1 to 201.8.175.254201.8.175.2554,094
140201.8.176.0/20201.8.176.1 to 201.8.191.254201.8.191.2554,094
141201.8.192.0/20201.8.192.1 to 201.8.207.254201.8.207.2554,094
142201.8.208.0/20201.8.208.1 to 201.8.223.254201.8.223.2554,094
143201.8.224.0/20201.8.224.1 to 201.8.239.254201.8.239.2554,094
144201.8.240.0/20201.8.240.1 to 201.8.255.254201.8.255.2554,094
145201.9.0.0/20201.9.0.1 to 201.9.15.254201.9.15.2554,094
146201.9.16.0/20201.9.16.1 to 201.9.31.254201.9.31.2554,094
147201.9.32.0/20201.9.32.1 to 201.9.47.254201.9.47.2554,094
148201.9.48.0/20201.9.48.1 to 201.9.63.254201.9.63.2554,094
149201.9.64.0/20201.9.64.1 to 201.9.79.254201.9.79.2554,094
150201.9.80.0/20201.9.80.1 to 201.9.95.254201.9.95.2554,094
151201.9.96.0/20201.9.96.1 to 201.9.111.254201.9.111.2554,094
152201.9.112.0/20201.9.112.1 to 201.9.127.254201.9.127.2554,094
153201.9.128.0/20201.9.128.1 to 201.9.143.254201.9.143.2554,094
154201.9.144.0/20201.9.144.1 to 201.9.159.254201.9.159.2554,094
155201.9.160.0/20201.9.160.1 to 201.9.175.254201.9.175.2554,094
156201.9.176.0/20201.9.176.1 to 201.9.191.254201.9.191.2554,094
157201.9.192.0/20201.9.192.1 to 201.9.207.254201.9.207.2554,094
158201.9.208.0/20201.9.208.1 to 201.9.223.254201.9.223.2554,094
159201.9.224.0/20201.9.224.1 to 201.9.239.254201.9.239.2554,094
160201.9.240.0/20201.9.240.1 to 201.9.255.254201.9.255.2554,094
161201.10.0.0/20201.10.0.1 to 201.10.15.254201.10.15.2554,094
162201.10.16.0/20201.10.16.1 to 201.10.31.254201.10.31.2554,094
163201.10.32.0/20201.10.32.1 to 201.10.47.254201.10.47.2554,094
164201.10.48.0/20201.10.48.1 to 201.10.63.254201.10.63.2554,094
165201.10.64.0/20201.10.64.1 to 201.10.79.254201.10.79.2554,094
166201.10.80.0/20201.10.80.1 to 201.10.95.254201.10.95.2554,094
167201.10.96.0/20201.10.96.1 to 201.10.111.254201.10.111.2554,094
168201.10.112.0/20201.10.112.1 to 201.10.127.254201.10.127.2554,094
169201.10.128.0/20201.10.128.1 to 201.10.143.254201.10.143.2554,094
170201.10.144.0/20201.10.144.1 to 201.10.159.254201.10.159.2554,094
171201.10.160.0/20201.10.160.1 to 201.10.175.254201.10.175.2554,094
172201.10.176.0/20201.10.176.1 to 201.10.191.254201.10.191.2554,094
173201.10.192.0/20201.10.192.1 to 201.10.207.254201.10.207.2554,094
174201.10.208.0/20201.10.208.1 to 201.10.223.254201.10.223.2554,094
175201.10.224.0/20201.10.224.1 to 201.10.239.254201.10.239.2554,094
176201.10.240.0/20201.10.240.1 to 201.10.255.254201.10.255.2554,094
177201.11.0.0/20201.11.0.1 to 201.11.15.254201.11.15.2554,094
178201.11.16.0/20201.11.16.1 to 201.11.31.254201.11.31.2554,094
179201.11.32.0/20201.11.32.1 to 201.11.47.254201.11.47.2554,094
180201.11.48.0/20201.11.48.1 to 201.11.63.254201.11.63.2554,094
181201.11.64.0/20201.11.64.1 to 201.11.79.254201.11.79.2554,094
182201.11.80.0/20201.11.80.1 to 201.11.95.254201.11.95.2554,094
183201.11.96.0/20201.11.96.1 to 201.11.111.254201.11.111.2554,094
184201.11.112.0/20201.11.112.1 to 201.11.127.254201.11.127.2554,094
185201.11.128.0/20201.11.128.1 to 201.11.143.254201.11.143.2554,094
186201.11.144.0/20201.11.144.1 to 201.11.159.254201.11.159.2554,094
187201.11.160.0/20201.11.160.1 to 201.11.175.254201.11.175.2554,094
188201.11.176.0/20201.11.176.1 to 201.11.191.254201.11.191.2554,094
189201.11.192.0/20201.11.192.1 to 201.11.207.254201.11.207.2554,094
190201.11.208.0/20201.11.208.1 to 201.11.223.254201.11.223.2554,094
191201.11.224.0/20201.11.224.1 to 201.11.239.254201.11.239.2554,094
192201.11.240.0/20201.11.240.1 to 201.11.255.254201.11.255.2554,094
193201.12.0.0/20201.12.0.1 to 201.12.15.254201.12.15.2554,094
194201.12.16.0/20201.12.16.1 to 201.12.31.254201.12.31.2554,094
195201.12.32.0/20201.12.32.1 to 201.12.47.254201.12.47.2554,094
196201.12.48.0/20201.12.48.1 to 201.12.63.254201.12.63.2554,094
197201.12.64.0/20201.12.64.1 to 201.12.79.254201.12.79.2554,094
198201.12.80.0/20201.12.80.1 to 201.12.95.254201.12.95.2554,094
199201.12.96.0/20201.12.96.1 to 201.12.111.254201.12.111.2554,094
200201.12.112.0/20201.12.112.1 to 201.12.127.254201.12.127.2554,094
201201.12.128.0/20201.12.128.1 to 201.12.143.254201.12.143.2554,094
202201.12.144.0/20201.12.144.1 to 201.12.159.254201.12.159.2554,094
203201.12.160.0/20201.12.160.1 to 201.12.175.254201.12.175.2554,094
204201.12.176.0/20201.12.176.1 to 201.12.191.254201.12.191.2554,094
205201.12.192.0/20201.12.192.1 to 201.12.207.254201.12.207.2554,094
206201.12.208.0/20201.12.208.1 to 201.12.223.254201.12.223.2554,094
207201.12.224.0/20201.12.224.1 to 201.12.239.254201.12.239.2554,094
208201.12.240.0/20201.12.240.1 to 201.12.255.254201.12.255.2554,094
209201.13.0.0/20201.13.0.1 to 201.13.15.254201.13.15.2554,094
210201.13.16.0/20201.13.16.1 to 201.13.31.254201.13.31.2554,094
211201.13.32.0/20201.13.32.1 to 201.13.47.254201.13.47.2554,094
212201.13.48.0/20201.13.48.1 to 201.13.63.254201.13.63.2554,094
213201.13.64.0/20201.13.64.1 to 201.13.79.254201.13.79.2554,094
214201.13.80.0/20201.13.80.1 to 201.13.95.254201.13.95.2554,094
215201.13.96.0/20201.13.96.1 to 201.13.111.254201.13.111.2554,094
216201.13.112.0/20201.13.112.1 to 201.13.127.254201.13.127.2554,094
217201.13.128.0/20201.13.128.1 to 201.13.143.254201.13.143.2554,094
218201.13.144.0/20201.13.144.1 to 201.13.159.254201.13.159.2554,094
219201.13.160.0/20201.13.160.1 to 201.13.175.254201.13.175.2554,094
220201.13.176.0/20201.13.176.1 to 201.13.191.254201.13.191.2554,094
221201.13.192.0/20201.13.192.1 to 201.13.207.254201.13.207.2554,094
222201.13.208.0/20201.13.208.1 to 201.13.223.254201.13.223.2554,094
223201.13.224.0/20201.13.224.1 to 201.13.239.254201.13.239.2554,094
224201.13.240.0/20201.13.240.1 to 201.13.255.254201.13.255.2554,094
225201.14.0.0/20201.14.0.1 to 201.14.15.254201.14.15.2554,094
226201.14.16.0/20201.14.16.1 to 201.14.31.254201.14.31.2554,094
227201.14.32.0/20201.14.32.1 to 201.14.47.254201.14.47.2554,094
228201.14.48.0/20201.14.48.1 to 201.14.63.254201.14.63.2554,094
229201.14.64.0/20201.14.64.1 to 201.14.79.254201.14.79.2554,094
230201.14.80.0/20201.14.80.1 to 201.14.95.254201.14.95.2554,094
231201.14.96.0/20201.14.96.1 to 201.14.111.254201.14.111.2554,094
232201.14.112.0/20201.14.112.1 to 201.14.127.254201.14.127.2554,094
233201.14.128.0/20201.14.128.1 to 201.14.143.254201.14.143.2554,094
234201.14.144.0/20201.14.144.1 to 201.14.159.254201.14.159.2554,094
235201.14.160.0/20201.14.160.1 to 201.14.175.254201.14.175.2554,094
236201.14.176.0/20201.14.176.1 to 201.14.191.254201.14.191.2554,094
237201.14.192.0/20201.14.192.1 to 201.14.207.254201.14.207.2554,094
238201.14.208.0/20201.14.208.1 to 201.14.223.254201.14.223.2554,094
239201.14.224.0/20201.14.224.1 to 201.14.239.254201.14.239.2554,094
240201.14.240.0/20201.14.240.1 to 201.14.255.254201.14.255.2554,094
241201.15.0.0/20201.15.0.1 to 201.15.15.254201.15.15.2554,094
242201.15.16.0/20201.15.16.1 to 201.15.31.254201.15.31.2554,094
243201.15.32.0/20201.15.32.1 to 201.15.47.254201.15.47.2554,094
244201.15.48.0/20201.15.48.1 to 201.15.63.254201.15.63.2554,094
245201.15.64.0/20201.15.64.1 to 201.15.79.254201.15.79.2554,094
246201.15.80.0/20201.15.80.1 to 201.15.95.254201.15.95.2554,094
247201.15.96.0/20201.15.96.1 to 201.15.111.254201.15.111.2554,094
248201.15.112.0/20201.15.112.1 to 201.15.127.254201.15.127.2554,094
249201.15.128.0/20201.15.128.1 to 201.15.143.254201.15.143.2554,094
250201.15.144.0/20201.15.144.1 to 201.15.159.254201.15.159.2554,094
251201.15.160.0/20201.15.160.1 to 201.15.175.254201.15.175.2554,094
252201.15.176.0/20201.15.176.1 to 201.15.191.254201.15.191.2554,094
253201.15.192.0/20201.15.192.1 to 201.15.207.254201.15.207.2554,094
254201.15.208.0/20201.15.208.1 to 201.15.223.254201.15.223.2554,094
255201.15.224.0/20201.15.224.1 to 201.15.239.254201.15.239.2554,094
256201.15.240.0/20201.15.240.1 to 201.15.255.254201.15.255.2554,094

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.