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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/17
/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 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1201.0.0.0/17201.0.0.1 to 201.0.127.254201.0.127.25532,766
2201.0.128.0/17201.0.128.1 to 201.0.255.254201.0.255.25532,766
3201.1.0.0/17201.1.0.1 to 201.1.127.254201.1.127.25532,766
4201.1.128.0/17201.1.128.1 to 201.1.255.254201.1.255.25532,766
5201.2.0.0/17201.2.0.1 to 201.2.127.254201.2.127.25532,766
6201.2.128.0/17201.2.128.1 to 201.2.255.254201.2.255.25532,766
7201.3.0.0/17201.3.0.1 to 201.3.127.254201.3.127.25532,766
8201.3.128.0/17201.3.128.1 to 201.3.255.254201.3.255.25532,766
9201.4.0.0/17201.4.0.1 to 201.4.127.254201.4.127.25532,766
10201.4.128.0/17201.4.128.1 to 201.4.255.254201.4.255.25532,766
11201.5.0.0/17201.5.0.1 to 201.5.127.254201.5.127.25532,766
12201.5.128.0/17201.5.128.1 to 201.5.255.254201.5.255.25532,766
13201.6.0.0/17201.6.0.1 to 201.6.127.254201.6.127.25532,766
14201.6.128.0/17201.6.128.1 to 201.6.255.254201.6.255.25532,766
15201.7.0.0/17201.7.0.1 to 201.7.127.254201.7.127.25532,766
16201.7.128.0/17201.7.128.1 to 201.7.255.254201.7.255.25532,766
17201.8.0.0/17201.8.0.1 to 201.8.127.254201.8.127.25532,766
18201.8.128.0/17201.8.128.1 to 201.8.255.254201.8.255.25532,766
19201.9.0.0/17201.9.0.1 to 201.9.127.254201.9.127.25532,766
20201.9.128.0/17201.9.128.1 to 201.9.255.254201.9.255.25532,766
21201.10.0.0/17201.10.0.1 to 201.10.127.254201.10.127.25532,766
22201.10.128.0/17201.10.128.1 to 201.10.255.254201.10.255.25532,766
23201.11.0.0/17201.11.0.1 to 201.11.127.254201.11.127.25532,766
24201.11.128.0/17201.11.128.1 to 201.11.255.254201.11.255.25532,766
25201.12.0.0/17201.12.0.1 to 201.12.127.254201.12.127.25532,766
26201.12.128.0/17201.12.128.1 to 201.12.255.254201.12.255.25532,766
27201.13.0.0/17201.13.0.1 to 201.13.127.254201.13.127.25532,766
28201.13.128.0/17201.13.128.1 to 201.13.255.254201.13.255.25532,766
29201.14.0.0/17201.14.0.1 to 201.14.127.254201.14.127.25532,766
30201.14.128.0/17201.14.128.1 to 201.14.255.254201.14.255.25532,766
31201.15.0.0/17201.15.0.1 to 201.15.127.254201.15.127.25532,766
32201.15.128.0/17201.15.128.1 to 201.15.255.254201.15.255.25532,766
33201.16.0.0/17201.16.0.1 to 201.16.127.254201.16.127.25532,766
34201.16.128.0/17201.16.128.1 to 201.16.255.254201.16.255.25532,766
35201.17.0.0/17201.17.0.1 to 201.17.127.254201.17.127.25532,766
36201.17.128.0/17201.17.128.1 to 201.17.255.254201.17.255.25532,766
37201.18.0.0/17201.18.0.1 to 201.18.127.254201.18.127.25532,766
38201.18.128.0/17201.18.128.1 to 201.18.255.254201.18.255.25532,766
39201.19.0.0/17201.19.0.1 to 201.19.127.254201.19.127.25532,766
40201.19.128.0/17201.19.128.1 to 201.19.255.254201.19.255.25532,766
41201.20.0.0/17201.20.0.1 to 201.20.127.254201.20.127.25532,766
42201.20.128.0/17201.20.128.1 to 201.20.255.254201.20.255.25532,766
43201.21.0.0/17201.21.0.1 to 201.21.127.254201.21.127.25532,766
44201.21.128.0/17201.21.128.1 to 201.21.255.254201.21.255.25532,766
45201.22.0.0/17201.22.0.1 to 201.22.127.254201.22.127.25532,766
46201.22.128.0/17201.22.128.1 to 201.22.255.254201.22.255.25532,766
47201.23.0.0/17201.23.0.1 to 201.23.127.254201.23.127.25532,766
48201.23.128.0/17201.23.128.1 to 201.23.255.254201.23.255.25532,766
49201.24.0.0/17201.24.0.1 to 201.24.127.254201.24.127.25532,766
50201.24.128.0/17201.24.128.1 to 201.24.255.254201.24.255.25532,766
51201.25.0.0/17201.25.0.1 to 201.25.127.254201.25.127.25532,766
52201.25.128.0/17201.25.128.1 to 201.25.255.254201.25.255.25532,766
53201.26.0.0/17201.26.0.1 to 201.26.127.254201.26.127.25532,766
54201.26.128.0/17201.26.128.1 to 201.26.255.254201.26.255.25532,766
55201.27.0.0/17201.27.0.1 to 201.27.127.254201.27.127.25532,766
56201.27.128.0/17201.27.128.1 to 201.27.255.254201.27.255.25532,766
57201.28.0.0/17201.28.0.1 to 201.28.127.254201.28.127.25532,766
58201.28.128.0/17201.28.128.1 to 201.28.255.254201.28.255.25532,766
59201.29.0.0/17201.29.0.1 to 201.29.127.254201.29.127.25532,766
60201.29.128.0/17201.29.128.1 to 201.29.255.254201.29.255.25532,766
61201.30.0.0/17201.30.0.1 to 201.30.127.254201.30.127.25532,766
62201.30.128.0/17201.30.128.1 to 201.30.255.254201.30.255.25532,766
63201.31.0.0/17201.31.0.1 to 201.31.127.254201.31.127.25532,766
64201.31.128.0/17201.31.128.1 to 201.31.255.254201.31.255.25532,766
65201.32.0.0/17201.32.0.1 to 201.32.127.254201.32.127.25532,766
66201.32.128.0/17201.32.128.1 to 201.32.255.254201.32.255.25532,766
67201.33.0.0/17201.33.0.1 to 201.33.127.254201.33.127.25532,766
68201.33.128.0/17201.33.128.1 to 201.33.255.254201.33.255.25532,766
69201.34.0.0/17201.34.0.1 to 201.34.127.254201.34.127.25532,766
70201.34.128.0/17201.34.128.1 to 201.34.255.254201.34.255.25532,766
71201.35.0.0/17201.35.0.1 to 201.35.127.254201.35.127.25532,766
72201.35.128.0/17201.35.128.1 to 201.35.255.254201.35.255.25532,766
73201.36.0.0/17201.36.0.1 to 201.36.127.254201.36.127.25532,766
74201.36.128.0/17201.36.128.1 to 201.36.255.254201.36.255.25532,766
75201.37.0.0/17201.37.0.1 to 201.37.127.254201.37.127.25532,766
76201.37.128.0/17201.37.128.1 to 201.37.255.254201.37.255.25532,766
77201.38.0.0/17201.38.0.1 to 201.38.127.254201.38.127.25532,766
78201.38.128.0/17201.38.128.1 to 201.38.255.254201.38.255.25532,766
79201.39.0.0/17201.39.0.1 to 201.39.127.254201.39.127.25532,766
80201.39.128.0/17201.39.128.1 to 201.39.255.254201.39.255.25532,766
81201.40.0.0/17201.40.0.1 to 201.40.127.254201.40.127.25532,766
82201.40.128.0/17201.40.128.1 to 201.40.255.254201.40.255.25532,766
83201.41.0.0/17201.41.0.1 to 201.41.127.254201.41.127.25532,766
84201.41.128.0/17201.41.128.1 to 201.41.255.254201.41.255.25532,766
85201.42.0.0/17201.42.0.1 to 201.42.127.254201.42.127.25532,766
86201.42.128.0/17201.42.128.1 to 201.42.255.254201.42.255.25532,766
87201.43.0.0/17201.43.0.1 to 201.43.127.254201.43.127.25532,766
88201.43.128.0/17201.43.128.1 to 201.43.255.254201.43.255.25532,766
89201.44.0.0/17201.44.0.1 to 201.44.127.254201.44.127.25532,766
90201.44.128.0/17201.44.128.1 to 201.44.255.254201.44.255.25532,766
91201.45.0.0/17201.45.0.1 to 201.45.127.254201.45.127.25532,766
92201.45.128.0/17201.45.128.1 to 201.45.255.254201.45.255.25532,766
93201.46.0.0/17201.46.0.1 to 201.46.127.254201.46.127.25532,766
94201.46.128.0/17201.46.128.1 to 201.46.255.254201.46.255.25532,766
95201.47.0.0/17201.47.0.1 to 201.47.127.254201.47.127.25532,766
96201.47.128.0/17201.47.128.1 to 201.47.255.254201.47.255.25532,766
97201.48.0.0/17201.48.0.1 to 201.48.127.254201.48.127.25532,766
98201.48.128.0/17201.48.128.1 to 201.48.255.254201.48.255.25532,766
99201.49.0.0/17201.49.0.1 to 201.49.127.254201.49.127.25532,766
100201.49.128.0/17201.49.128.1 to 201.49.255.254201.49.255.25532,766
101201.50.0.0/17201.50.0.1 to 201.50.127.254201.50.127.25532,766
102201.50.128.0/17201.50.128.1 to 201.50.255.254201.50.255.25532,766
103201.51.0.0/17201.51.0.1 to 201.51.127.254201.51.127.25532,766
104201.51.128.0/17201.51.128.1 to 201.51.255.254201.51.255.25532,766
105201.52.0.0/17201.52.0.1 to 201.52.127.254201.52.127.25532,766
106201.52.128.0/17201.52.128.1 to 201.52.255.254201.52.255.25532,766
107201.53.0.0/17201.53.0.1 to 201.53.127.254201.53.127.25532,766
108201.53.128.0/17201.53.128.1 to 201.53.255.254201.53.255.25532,766
109201.54.0.0/17201.54.0.1 to 201.54.127.254201.54.127.25532,766
110201.54.128.0/17201.54.128.1 to 201.54.255.254201.54.255.25532,766
111201.55.0.0/17201.55.0.1 to 201.55.127.254201.55.127.25532,766
112201.55.128.0/17201.55.128.1 to 201.55.255.254201.55.255.25532,766
113201.56.0.0/17201.56.0.1 to 201.56.127.254201.56.127.25532,766
114201.56.128.0/17201.56.128.1 to 201.56.255.254201.56.255.25532,766
115201.57.0.0/17201.57.0.1 to 201.57.127.254201.57.127.25532,766
116201.57.128.0/17201.57.128.1 to 201.57.255.254201.57.255.25532,766
117201.58.0.0/17201.58.0.1 to 201.58.127.254201.58.127.25532,766
118201.58.128.0/17201.58.128.1 to 201.58.255.254201.58.255.25532,766
119201.59.0.0/17201.59.0.1 to 201.59.127.254201.59.127.25532,766
120201.59.128.0/17201.59.128.1 to 201.59.255.254201.59.255.25532,766
121201.60.0.0/17201.60.0.1 to 201.60.127.254201.60.127.25532,766
122201.60.128.0/17201.60.128.1 to 201.60.255.254201.60.255.25532,766
123201.61.0.0/17201.61.0.1 to 201.61.127.254201.61.127.25532,766
124201.61.128.0/17201.61.128.1 to 201.61.255.254201.61.255.25532,766
125201.62.0.0/17201.62.0.1 to 201.62.127.254201.62.127.25532,766
126201.62.128.0/17201.62.128.1 to 201.62.255.254201.62.255.25532,766
127201.63.0.0/17201.63.0.1 to 201.63.127.254201.63.127.25532,766
128201.63.128.0/17201.63.128.1 to 201.63.255.254201.63.255.25532,766
129201.64.0.0/17201.64.0.1 to 201.64.127.254201.64.127.25532,766
130201.64.128.0/17201.64.128.1 to 201.64.255.254201.64.255.25532,766
131201.65.0.0/17201.65.0.1 to 201.65.127.254201.65.127.25532,766
132201.65.128.0/17201.65.128.1 to 201.65.255.254201.65.255.25532,766
133201.66.0.0/17201.66.0.1 to 201.66.127.254201.66.127.25532,766
134201.66.128.0/17201.66.128.1 to 201.66.255.254201.66.255.25532,766
135201.67.0.0/17201.67.0.1 to 201.67.127.254201.67.127.25532,766
136201.67.128.0/17201.67.128.1 to 201.67.255.254201.67.255.25532,766
137201.68.0.0/17201.68.0.1 to 201.68.127.254201.68.127.25532,766
138201.68.128.0/17201.68.128.1 to 201.68.255.254201.68.255.25532,766
139201.69.0.0/17201.69.0.1 to 201.69.127.254201.69.127.25532,766
140201.69.128.0/17201.69.128.1 to 201.69.255.254201.69.255.25532,766
141201.70.0.0/17201.70.0.1 to 201.70.127.254201.70.127.25532,766
142201.70.128.0/17201.70.128.1 to 201.70.255.254201.70.255.25532,766
143201.71.0.0/17201.71.0.1 to 201.71.127.254201.71.127.25532,766
144201.71.128.0/17201.71.128.1 to 201.71.255.254201.71.255.25532,766
145201.72.0.0/17201.72.0.1 to 201.72.127.254201.72.127.25532,766
146201.72.128.0/17201.72.128.1 to 201.72.255.254201.72.255.25532,766
147201.73.0.0/17201.73.0.1 to 201.73.127.254201.73.127.25532,766
148201.73.128.0/17201.73.128.1 to 201.73.255.254201.73.255.25532,766
149201.74.0.0/17201.74.0.1 to 201.74.127.254201.74.127.25532,766
150201.74.128.0/17201.74.128.1 to 201.74.255.254201.74.255.25532,766
151201.75.0.0/17201.75.0.1 to 201.75.127.254201.75.127.25532,766
152201.75.128.0/17201.75.128.1 to 201.75.255.254201.75.255.25532,766
153201.76.0.0/17201.76.0.1 to 201.76.127.254201.76.127.25532,766
154201.76.128.0/17201.76.128.1 to 201.76.255.254201.76.255.25532,766
155201.77.0.0/17201.77.0.1 to 201.77.127.254201.77.127.25532,766
156201.77.128.0/17201.77.128.1 to 201.77.255.254201.77.255.25532,766
157201.78.0.0/17201.78.0.1 to 201.78.127.254201.78.127.25532,766
158201.78.128.0/17201.78.128.1 to 201.78.255.254201.78.255.25532,766
159201.79.0.0/17201.79.0.1 to 201.79.127.254201.79.127.25532,766
160201.79.128.0/17201.79.128.1 to 201.79.255.254201.79.255.25532,766
161201.80.0.0/17201.80.0.1 to 201.80.127.254201.80.127.25532,766
162201.80.128.0/17201.80.128.1 to 201.80.255.254201.80.255.25532,766
163201.81.0.0/17201.81.0.1 to 201.81.127.254201.81.127.25532,766
164201.81.128.0/17201.81.128.1 to 201.81.255.254201.81.255.25532,766
165201.82.0.0/17201.82.0.1 to 201.82.127.254201.82.127.25532,766
166201.82.128.0/17201.82.128.1 to 201.82.255.254201.82.255.25532,766
167201.83.0.0/17201.83.0.1 to 201.83.127.254201.83.127.25532,766
168201.83.128.0/17201.83.128.1 to 201.83.255.254201.83.255.25532,766
169201.84.0.0/17201.84.0.1 to 201.84.127.254201.84.127.25532,766
170201.84.128.0/17201.84.128.1 to 201.84.255.254201.84.255.25532,766
171201.85.0.0/17201.85.0.1 to 201.85.127.254201.85.127.25532,766
172201.85.128.0/17201.85.128.1 to 201.85.255.254201.85.255.25532,766
173201.86.0.0/17201.86.0.1 to 201.86.127.254201.86.127.25532,766
174201.86.128.0/17201.86.128.1 to 201.86.255.254201.86.255.25532,766
175201.87.0.0/17201.87.0.1 to 201.87.127.254201.87.127.25532,766
176201.87.128.0/17201.87.128.1 to 201.87.255.254201.87.255.25532,766
177201.88.0.0/17201.88.0.1 to 201.88.127.254201.88.127.25532,766
178201.88.128.0/17201.88.128.1 to 201.88.255.254201.88.255.25532,766
179201.89.0.0/17201.89.0.1 to 201.89.127.254201.89.127.25532,766
180201.89.128.0/17201.89.128.1 to 201.89.255.254201.89.255.25532,766
181201.90.0.0/17201.90.0.1 to 201.90.127.254201.90.127.25532,766
182201.90.128.0/17201.90.128.1 to 201.90.255.254201.90.255.25532,766
183201.91.0.0/17201.91.0.1 to 201.91.127.254201.91.127.25532,766
184201.91.128.0/17201.91.128.1 to 201.91.255.254201.91.255.25532,766
185201.92.0.0/17201.92.0.1 to 201.92.127.254201.92.127.25532,766
186201.92.128.0/17201.92.128.1 to 201.92.255.254201.92.255.25532,766
187201.93.0.0/17201.93.0.1 to 201.93.127.254201.93.127.25532,766
188201.93.128.0/17201.93.128.1 to 201.93.255.254201.93.255.25532,766
189201.94.0.0/17201.94.0.1 to 201.94.127.254201.94.127.25532,766
190201.94.128.0/17201.94.128.1 to 201.94.255.254201.94.255.25532,766
191201.95.0.0/17201.95.0.1 to 201.95.127.254201.95.127.25532,766
192201.95.128.0/17201.95.128.1 to 201.95.255.254201.95.255.25532,766
193201.96.0.0/17201.96.0.1 to 201.96.127.254201.96.127.25532,766
194201.96.128.0/17201.96.128.1 to 201.96.255.254201.96.255.25532,766
195201.97.0.0/17201.97.0.1 to 201.97.127.254201.97.127.25532,766
196201.97.128.0/17201.97.128.1 to 201.97.255.254201.97.255.25532,766
197201.98.0.0/17201.98.0.1 to 201.98.127.254201.98.127.25532,766
198201.98.128.0/17201.98.128.1 to 201.98.255.254201.98.255.25532,766
199201.99.0.0/17201.99.0.1 to 201.99.127.254201.99.127.25532,766
200201.99.128.0/17201.99.128.1 to 201.99.255.254201.99.255.25532,766
201201.100.0.0/17201.100.0.1 to 201.100.127.254201.100.127.25532,766
202201.100.128.0/17201.100.128.1 to 201.100.255.254201.100.255.25532,766
203201.101.0.0/17201.101.0.1 to 201.101.127.254201.101.127.25532,766
204201.101.128.0/17201.101.128.1 to 201.101.255.254201.101.255.25532,766
205201.102.0.0/17201.102.0.1 to 201.102.127.254201.102.127.25532,766
206201.102.128.0/17201.102.128.1 to 201.102.255.254201.102.255.25532,766
207201.103.0.0/17201.103.0.1 to 201.103.127.254201.103.127.25532,766
208201.103.128.0/17201.103.128.1 to 201.103.255.254201.103.255.25532,766
209201.104.0.0/17201.104.0.1 to 201.104.127.254201.104.127.25532,766
210201.104.128.0/17201.104.128.1 to 201.104.255.254201.104.255.25532,766
211201.105.0.0/17201.105.0.1 to 201.105.127.254201.105.127.25532,766
212201.105.128.0/17201.105.128.1 to 201.105.255.254201.105.255.25532,766
213201.106.0.0/17201.106.0.1 to 201.106.127.254201.106.127.25532,766
214201.106.128.0/17201.106.128.1 to 201.106.255.254201.106.255.25532,766
215201.107.0.0/17201.107.0.1 to 201.107.127.254201.107.127.25532,766
216201.107.128.0/17201.107.128.1 to 201.107.255.254201.107.255.25532,766
217201.108.0.0/17201.108.0.1 to 201.108.127.254201.108.127.25532,766
218201.108.128.0/17201.108.128.1 to 201.108.255.254201.108.255.25532,766
219201.109.0.0/17201.109.0.1 to 201.109.127.254201.109.127.25532,766
220201.109.128.0/17201.109.128.1 to 201.109.255.254201.109.255.25532,766
221201.110.0.0/17201.110.0.1 to 201.110.127.254201.110.127.25532,766
222201.110.128.0/17201.110.128.1 to 201.110.255.254201.110.255.25532,766
223201.111.0.0/17201.111.0.1 to 201.111.127.254201.111.127.25532,766
224201.111.128.0/17201.111.128.1 to 201.111.255.254201.111.255.25532,766
225201.112.0.0/17201.112.0.1 to 201.112.127.254201.112.127.25532,766
226201.112.128.0/17201.112.128.1 to 201.112.255.254201.112.255.25532,766
227201.113.0.0/17201.113.0.1 to 201.113.127.254201.113.127.25532,766
228201.113.128.0/17201.113.128.1 to 201.113.255.254201.113.255.25532,766
229201.114.0.0/17201.114.0.1 to 201.114.127.254201.114.127.25532,766
230201.114.128.0/17201.114.128.1 to 201.114.255.254201.114.255.25532,766
231201.115.0.0/17201.115.0.1 to 201.115.127.254201.115.127.25532,766
232201.115.128.0/17201.115.128.1 to 201.115.255.254201.115.255.25532,766
233201.116.0.0/17201.116.0.1 to 201.116.127.254201.116.127.25532,766
234201.116.128.0/17201.116.128.1 to 201.116.255.254201.116.255.25532,766
235201.117.0.0/17201.117.0.1 to 201.117.127.254201.117.127.25532,766
236201.117.128.0/17201.117.128.1 to 201.117.255.254201.117.255.25532,766
237201.118.0.0/17201.118.0.1 to 201.118.127.254201.118.127.25532,766
238201.118.128.0/17201.118.128.1 to 201.118.255.254201.118.255.25532,766
239201.119.0.0/17201.119.0.1 to 201.119.127.254201.119.127.25532,766
240201.119.128.0/17201.119.128.1 to 201.119.255.254201.119.255.25532,766
241201.120.0.0/17201.120.0.1 to 201.120.127.254201.120.127.25532,766
242201.120.128.0/17201.120.128.1 to 201.120.255.254201.120.255.25532,766
243201.121.0.0/17201.121.0.1 to 201.121.127.254201.121.127.25532,766
244201.121.128.0/17201.121.128.1 to 201.121.255.254201.121.255.25532,766
245201.122.0.0/17201.122.0.1 to 201.122.127.254201.122.127.25532,766
246201.122.128.0/17201.122.128.1 to 201.122.255.254201.122.255.25532,766
247201.123.0.0/17201.123.0.1 to 201.123.127.254201.123.127.25532,766
248201.123.128.0/17201.123.128.1 to 201.123.255.254201.123.255.25532,766
249201.124.0.0/17201.124.0.1 to 201.124.127.254201.124.127.25532,766
250201.124.128.0/17201.124.128.1 to 201.124.255.254201.124.255.25532,766
251201.125.0.0/17201.125.0.1 to 201.125.127.254201.125.127.25532,766
252201.125.128.0/17201.125.128.1 to 201.125.255.254201.125.255.25532,766
253201.126.0.0/17201.126.0.1 to 201.126.127.254201.126.127.25532,766
254201.126.128.0/17201.126.128.1 to 201.126.255.254201.126.255.25532,766
255201.127.0.0/17201.127.0.1 to 201.127.127.254201.127.127.25532,766
256201.127.128.0/17201.127.128.1 to 201.127.255.254201.127.255.25532,766

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.