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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.

Network207.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
207.0.0.0
Broadcast address
207.255.255.255
First usable
207.0.0.1
Last usable
207.255.255.254
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 CF000000 · Integer 3472883712 to 3489660927
Reverse DNS zone
207.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001111..00000000.00000000.00000000207.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11001111..00000000.00000000.00000000207.0.0.0
Broadcast11001111..11111111.11111111.11111111207.255.255.255
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)

207.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1207.0.0.0/17207.0.0.1 to 207.0.127.254207.0.127.25532,766
2207.0.128.0/17207.0.128.1 to 207.0.255.254207.0.255.25532,766
3207.1.0.0/17207.1.0.1 to 207.1.127.254207.1.127.25532,766
4207.1.128.0/17207.1.128.1 to 207.1.255.254207.1.255.25532,766
5207.2.0.0/17207.2.0.1 to 207.2.127.254207.2.127.25532,766
6207.2.128.0/17207.2.128.1 to 207.2.255.254207.2.255.25532,766
7207.3.0.0/17207.3.0.1 to 207.3.127.254207.3.127.25532,766
8207.3.128.0/17207.3.128.1 to 207.3.255.254207.3.255.25532,766
9207.4.0.0/17207.4.0.1 to 207.4.127.254207.4.127.25532,766
10207.4.128.0/17207.4.128.1 to 207.4.255.254207.4.255.25532,766
11207.5.0.0/17207.5.0.1 to 207.5.127.254207.5.127.25532,766
12207.5.128.0/17207.5.128.1 to 207.5.255.254207.5.255.25532,766
13207.6.0.0/17207.6.0.1 to 207.6.127.254207.6.127.25532,766
14207.6.128.0/17207.6.128.1 to 207.6.255.254207.6.255.25532,766
15207.7.0.0/17207.7.0.1 to 207.7.127.254207.7.127.25532,766
16207.7.128.0/17207.7.128.1 to 207.7.255.254207.7.255.25532,766
17207.8.0.0/17207.8.0.1 to 207.8.127.254207.8.127.25532,766
18207.8.128.0/17207.8.128.1 to 207.8.255.254207.8.255.25532,766
19207.9.0.0/17207.9.0.1 to 207.9.127.254207.9.127.25532,766
20207.9.128.0/17207.9.128.1 to 207.9.255.254207.9.255.25532,766
21207.10.0.0/17207.10.0.1 to 207.10.127.254207.10.127.25532,766
22207.10.128.0/17207.10.128.1 to 207.10.255.254207.10.255.25532,766
23207.11.0.0/17207.11.0.1 to 207.11.127.254207.11.127.25532,766
24207.11.128.0/17207.11.128.1 to 207.11.255.254207.11.255.25532,766
25207.12.0.0/17207.12.0.1 to 207.12.127.254207.12.127.25532,766
26207.12.128.0/17207.12.128.1 to 207.12.255.254207.12.255.25532,766
27207.13.0.0/17207.13.0.1 to 207.13.127.254207.13.127.25532,766
28207.13.128.0/17207.13.128.1 to 207.13.255.254207.13.255.25532,766
29207.14.0.0/17207.14.0.1 to 207.14.127.254207.14.127.25532,766
30207.14.128.0/17207.14.128.1 to 207.14.255.254207.14.255.25532,766
31207.15.0.0/17207.15.0.1 to 207.15.127.254207.15.127.25532,766
32207.15.128.0/17207.15.128.1 to 207.15.255.254207.15.255.25532,766
33207.16.0.0/17207.16.0.1 to 207.16.127.254207.16.127.25532,766
34207.16.128.0/17207.16.128.1 to 207.16.255.254207.16.255.25532,766
35207.17.0.0/17207.17.0.1 to 207.17.127.254207.17.127.25532,766
36207.17.128.0/17207.17.128.1 to 207.17.255.254207.17.255.25532,766
37207.18.0.0/17207.18.0.1 to 207.18.127.254207.18.127.25532,766
38207.18.128.0/17207.18.128.1 to 207.18.255.254207.18.255.25532,766
39207.19.0.0/17207.19.0.1 to 207.19.127.254207.19.127.25532,766
40207.19.128.0/17207.19.128.1 to 207.19.255.254207.19.255.25532,766
41207.20.0.0/17207.20.0.1 to 207.20.127.254207.20.127.25532,766
42207.20.128.0/17207.20.128.1 to 207.20.255.254207.20.255.25532,766
43207.21.0.0/17207.21.0.1 to 207.21.127.254207.21.127.25532,766
44207.21.128.0/17207.21.128.1 to 207.21.255.254207.21.255.25532,766
45207.22.0.0/17207.22.0.1 to 207.22.127.254207.22.127.25532,766
46207.22.128.0/17207.22.128.1 to 207.22.255.254207.22.255.25532,766
47207.23.0.0/17207.23.0.1 to 207.23.127.254207.23.127.25532,766
48207.23.128.0/17207.23.128.1 to 207.23.255.254207.23.255.25532,766
49207.24.0.0/17207.24.0.1 to 207.24.127.254207.24.127.25532,766
50207.24.128.0/17207.24.128.1 to 207.24.255.254207.24.255.25532,766
51207.25.0.0/17207.25.0.1 to 207.25.127.254207.25.127.25532,766
52207.25.128.0/17207.25.128.1 to 207.25.255.254207.25.255.25532,766
53207.26.0.0/17207.26.0.1 to 207.26.127.254207.26.127.25532,766
54207.26.128.0/17207.26.128.1 to 207.26.255.254207.26.255.25532,766
55207.27.0.0/17207.27.0.1 to 207.27.127.254207.27.127.25532,766
56207.27.128.0/17207.27.128.1 to 207.27.255.254207.27.255.25532,766
57207.28.0.0/17207.28.0.1 to 207.28.127.254207.28.127.25532,766
58207.28.128.0/17207.28.128.1 to 207.28.255.254207.28.255.25532,766
59207.29.0.0/17207.29.0.1 to 207.29.127.254207.29.127.25532,766
60207.29.128.0/17207.29.128.1 to 207.29.255.254207.29.255.25532,766
61207.30.0.0/17207.30.0.1 to 207.30.127.254207.30.127.25532,766
62207.30.128.0/17207.30.128.1 to 207.30.255.254207.30.255.25532,766
63207.31.0.0/17207.31.0.1 to 207.31.127.254207.31.127.25532,766
64207.31.128.0/17207.31.128.1 to 207.31.255.254207.31.255.25532,766
65207.32.0.0/17207.32.0.1 to 207.32.127.254207.32.127.25532,766
66207.32.128.0/17207.32.128.1 to 207.32.255.254207.32.255.25532,766
67207.33.0.0/17207.33.0.1 to 207.33.127.254207.33.127.25532,766
68207.33.128.0/17207.33.128.1 to 207.33.255.254207.33.255.25532,766
69207.34.0.0/17207.34.0.1 to 207.34.127.254207.34.127.25532,766
70207.34.128.0/17207.34.128.1 to 207.34.255.254207.34.255.25532,766
71207.35.0.0/17207.35.0.1 to 207.35.127.254207.35.127.25532,766
72207.35.128.0/17207.35.128.1 to 207.35.255.254207.35.255.25532,766
73207.36.0.0/17207.36.0.1 to 207.36.127.254207.36.127.25532,766
74207.36.128.0/17207.36.128.1 to 207.36.255.254207.36.255.25532,766
75207.37.0.0/17207.37.0.1 to 207.37.127.254207.37.127.25532,766
76207.37.128.0/17207.37.128.1 to 207.37.255.254207.37.255.25532,766
77207.38.0.0/17207.38.0.1 to 207.38.127.254207.38.127.25532,766
78207.38.128.0/17207.38.128.1 to 207.38.255.254207.38.255.25532,766
79207.39.0.0/17207.39.0.1 to 207.39.127.254207.39.127.25532,766
80207.39.128.0/17207.39.128.1 to 207.39.255.254207.39.255.25532,766
81207.40.0.0/17207.40.0.1 to 207.40.127.254207.40.127.25532,766
82207.40.128.0/17207.40.128.1 to 207.40.255.254207.40.255.25532,766
83207.41.0.0/17207.41.0.1 to 207.41.127.254207.41.127.25532,766
84207.41.128.0/17207.41.128.1 to 207.41.255.254207.41.255.25532,766
85207.42.0.0/17207.42.0.1 to 207.42.127.254207.42.127.25532,766
86207.42.128.0/17207.42.128.1 to 207.42.255.254207.42.255.25532,766
87207.43.0.0/17207.43.0.1 to 207.43.127.254207.43.127.25532,766
88207.43.128.0/17207.43.128.1 to 207.43.255.254207.43.255.25532,766
89207.44.0.0/17207.44.0.1 to 207.44.127.254207.44.127.25532,766
90207.44.128.0/17207.44.128.1 to 207.44.255.254207.44.255.25532,766
91207.45.0.0/17207.45.0.1 to 207.45.127.254207.45.127.25532,766
92207.45.128.0/17207.45.128.1 to 207.45.255.254207.45.255.25532,766
93207.46.0.0/17207.46.0.1 to 207.46.127.254207.46.127.25532,766
94207.46.128.0/17207.46.128.1 to 207.46.255.254207.46.255.25532,766
95207.47.0.0/17207.47.0.1 to 207.47.127.254207.47.127.25532,766
96207.47.128.0/17207.47.128.1 to 207.47.255.254207.47.255.25532,766
97207.48.0.0/17207.48.0.1 to 207.48.127.254207.48.127.25532,766
98207.48.128.0/17207.48.128.1 to 207.48.255.254207.48.255.25532,766
99207.49.0.0/17207.49.0.1 to 207.49.127.254207.49.127.25532,766
100207.49.128.0/17207.49.128.1 to 207.49.255.254207.49.255.25532,766
101207.50.0.0/17207.50.0.1 to 207.50.127.254207.50.127.25532,766
102207.50.128.0/17207.50.128.1 to 207.50.255.254207.50.255.25532,766
103207.51.0.0/17207.51.0.1 to 207.51.127.254207.51.127.25532,766
104207.51.128.0/17207.51.128.1 to 207.51.255.254207.51.255.25532,766
105207.52.0.0/17207.52.0.1 to 207.52.127.254207.52.127.25532,766
106207.52.128.0/17207.52.128.1 to 207.52.255.254207.52.255.25532,766
107207.53.0.0/17207.53.0.1 to 207.53.127.254207.53.127.25532,766
108207.53.128.0/17207.53.128.1 to 207.53.255.254207.53.255.25532,766
109207.54.0.0/17207.54.0.1 to 207.54.127.254207.54.127.25532,766
110207.54.128.0/17207.54.128.1 to 207.54.255.254207.54.255.25532,766
111207.55.0.0/17207.55.0.1 to 207.55.127.254207.55.127.25532,766
112207.55.128.0/17207.55.128.1 to 207.55.255.254207.55.255.25532,766
113207.56.0.0/17207.56.0.1 to 207.56.127.254207.56.127.25532,766
114207.56.128.0/17207.56.128.1 to 207.56.255.254207.56.255.25532,766
115207.57.0.0/17207.57.0.1 to 207.57.127.254207.57.127.25532,766
116207.57.128.0/17207.57.128.1 to 207.57.255.254207.57.255.25532,766
117207.58.0.0/17207.58.0.1 to 207.58.127.254207.58.127.25532,766
118207.58.128.0/17207.58.128.1 to 207.58.255.254207.58.255.25532,766
119207.59.0.0/17207.59.0.1 to 207.59.127.254207.59.127.25532,766
120207.59.128.0/17207.59.128.1 to 207.59.255.254207.59.255.25532,766
121207.60.0.0/17207.60.0.1 to 207.60.127.254207.60.127.25532,766
122207.60.128.0/17207.60.128.1 to 207.60.255.254207.60.255.25532,766
123207.61.0.0/17207.61.0.1 to 207.61.127.254207.61.127.25532,766
124207.61.128.0/17207.61.128.1 to 207.61.255.254207.61.255.25532,766
125207.62.0.0/17207.62.0.1 to 207.62.127.254207.62.127.25532,766
126207.62.128.0/17207.62.128.1 to 207.62.255.254207.62.255.25532,766
127207.63.0.0/17207.63.0.1 to 207.63.127.254207.63.127.25532,766
128207.63.128.0/17207.63.128.1 to 207.63.255.254207.63.255.25532,766
129207.64.0.0/17207.64.0.1 to 207.64.127.254207.64.127.25532,766
130207.64.128.0/17207.64.128.1 to 207.64.255.254207.64.255.25532,766
131207.65.0.0/17207.65.0.1 to 207.65.127.254207.65.127.25532,766
132207.65.128.0/17207.65.128.1 to 207.65.255.254207.65.255.25532,766
133207.66.0.0/17207.66.0.1 to 207.66.127.254207.66.127.25532,766
134207.66.128.0/17207.66.128.1 to 207.66.255.254207.66.255.25532,766
135207.67.0.0/17207.67.0.1 to 207.67.127.254207.67.127.25532,766
136207.67.128.0/17207.67.128.1 to 207.67.255.254207.67.255.25532,766
137207.68.0.0/17207.68.0.1 to 207.68.127.254207.68.127.25532,766
138207.68.128.0/17207.68.128.1 to 207.68.255.254207.68.255.25532,766
139207.69.0.0/17207.69.0.1 to 207.69.127.254207.69.127.25532,766
140207.69.128.0/17207.69.128.1 to 207.69.255.254207.69.255.25532,766
141207.70.0.0/17207.70.0.1 to 207.70.127.254207.70.127.25532,766
142207.70.128.0/17207.70.128.1 to 207.70.255.254207.70.255.25532,766
143207.71.0.0/17207.71.0.1 to 207.71.127.254207.71.127.25532,766
144207.71.128.0/17207.71.128.1 to 207.71.255.254207.71.255.25532,766
145207.72.0.0/17207.72.0.1 to 207.72.127.254207.72.127.25532,766
146207.72.128.0/17207.72.128.1 to 207.72.255.254207.72.255.25532,766
147207.73.0.0/17207.73.0.1 to 207.73.127.254207.73.127.25532,766
148207.73.128.0/17207.73.128.1 to 207.73.255.254207.73.255.25532,766
149207.74.0.0/17207.74.0.1 to 207.74.127.254207.74.127.25532,766
150207.74.128.0/17207.74.128.1 to 207.74.255.254207.74.255.25532,766
151207.75.0.0/17207.75.0.1 to 207.75.127.254207.75.127.25532,766
152207.75.128.0/17207.75.128.1 to 207.75.255.254207.75.255.25532,766
153207.76.0.0/17207.76.0.1 to 207.76.127.254207.76.127.25532,766
154207.76.128.0/17207.76.128.1 to 207.76.255.254207.76.255.25532,766
155207.77.0.0/17207.77.0.1 to 207.77.127.254207.77.127.25532,766
156207.77.128.0/17207.77.128.1 to 207.77.255.254207.77.255.25532,766
157207.78.0.0/17207.78.0.1 to 207.78.127.254207.78.127.25532,766
158207.78.128.0/17207.78.128.1 to 207.78.255.254207.78.255.25532,766
159207.79.0.0/17207.79.0.1 to 207.79.127.254207.79.127.25532,766
160207.79.128.0/17207.79.128.1 to 207.79.255.254207.79.255.25532,766
161207.80.0.0/17207.80.0.1 to 207.80.127.254207.80.127.25532,766
162207.80.128.0/17207.80.128.1 to 207.80.255.254207.80.255.25532,766
163207.81.0.0/17207.81.0.1 to 207.81.127.254207.81.127.25532,766
164207.81.128.0/17207.81.128.1 to 207.81.255.254207.81.255.25532,766
165207.82.0.0/17207.82.0.1 to 207.82.127.254207.82.127.25532,766
166207.82.128.0/17207.82.128.1 to 207.82.255.254207.82.255.25532,766
167207.83.0.0/17207.83.0.1 to 207.83.127.254207.83.127.25532,766
168207.83.128.0/17207.83.128.1 to 207.83.255.254207.83.255.25532,766
169207.84.0.0/17207.84.0.1 to 207.84.127.254207.84.127.25532,766
170207.84.128.0/17207.84.128.1 to 207.84.255.254207.84.255.25532,766
171207.85.0.0/17207.85.0.1 to 207.85.127.254207.85.127.25532,766
172207.85.128.0/17207.85.128.1 to 207.85.255.254207.85.255.25532,766
173207.86.0.0/17207.86.0.1 to 207.86.127.254207.86.127.25532,766
174207.86.128.0/17207.86.128.1 to 207.86.255.254207.86.255.25532,766
175207.87.0.0/17207.87.0.1 to 207.87.127.254207.87.127.25532,766
176207.87.128.0/17207.87.128.1 to 207.87.255.254207.87.255.25532,766
177207.88.0.0/17207.88.0.1 to 207.88.127.254207.88.127.25532,766
178207.88.128.0/17207.88.128.1 to 207.88.255.254207.88.255.25532,766
179207.89.0.0/17207.89.0.1 to 207.89.127.254207.89.127.25532,766
180207.89.128.0/17207.89.128.1 to 207.89.255.254207.89.255.25532,766
181207.90.0.0/17207.90.0.1 to 207.90.127.254207.90.127.25532,766
182207.90.128.0/17207.90.128.1 to 207.90.255.254207.90.255.25532,766
183207.91.0.0/17207.91.0.1 to 207.91.127.254207.91.127.25532,766
184207.91.128.0/17207.91.128.1 to 207.91.255.254207.91.255.25532,766
185207.92.0.0/17207.92.0.1 to 207.92.127.254207.92.127.25532,766
186207.92.128.0/17207.92.128.1 to 207.92.255.254207.92.255.25532,766
187207.93.0.0/17207.93.0.1 to 207.93.127.254207.93.127.25532,766
188207.93.128.0/17207.93.128.1 to 207.93.255.254207.93.255.25532,766
189207.94.0.0/17207.94.0.1 to 207.94.127.254207.94.127.25532,766
190207.94.128.0/17207.94.128.1 to 207.94.255.254207.94.255.25532,766
191207.95.0.0/17207.95.0.1 to 207.95.127.254207.95.127.25532,766
192207.95.128.0/17207.95.128.1 to 207.95.255.254207.95.255.25532,766
193207.96.0.0/17207.96.0.1 to 207.96.127.254207.96.127.25532,766
194207.96.128.0/17207.96.128.1 to 207.96.255.254207.96.255.25532,766
195207.97.0.0/17207.97.0.1 to 207.97.127.254207.97.127.25532,766
196207.97.128.0/17207.97.128.1 to 207.97.255.254207.97.255.25532,766
197207.98.0.0/17207.98.0.1 to 207.98.127.254207.98.127.25532,766
198207.98.128.0/17207.98.128.1 to 207.98.255.254207.98.255.25532,766
199207.99.0.0/17207.99.0.1 to 207.99.127.254207.99.127.25532,766
200207.99.128.0/17207.99.128.1 to 207.99.255.254207.99.255.25532,766
201207.100.0.0/17207.100.0.1 to 207.100.127.254207.100.127.25532,766
202207.100.128.0/17207.100.128.1 to 207.100.255.254207.100.255.25532,766
203207.101.0.0/17207.101.0.1 to 207.101.127.254207.101.127.25532,766
204207.101.128.0/17207.101.128.1 to 207.101.255.254207.101.255.25532,766
205207.102.0.0/17207.102.0.1 to 207.102.127.254207.102.127.25532,766
206207.102.128.0/17207.102.128.1 to 207.102.255.254207.102.255.25532,766
207207.103.0.0/17207.103.0.1 to 207.103.127.254207.103.127.25532,766
208207.103.128.0/17207.103.128.1 to 207.103.255.254207.103.255.25532,766
209207.104.0.0/17207.104.0.1 to 207.104.127.254207.104.127.25532,766
210207.104.128.0/17207.104.128.1 to 207.104.255.254207.104.255.25532,766
211207.105.0.0/17207.105.0.1 to 207.105.127.254207.105.127.25532,766
212207.105.128.0/17207.105.128.1 to 207.105.255.254207.105.255.25532,766
213207.106.0.0/17207.106.0.1 to 207.106.127.254207.106.127.25532,766
214207.106.128.0/17207.106.128.1 to 207.106.255.254207.106.255.25532,766
215207.107.0.0/17207.107.0.1 to 207.107.127.254207.107.127.25532,766
216207.107.128.0/17207.107.128.1 to 207.107.255.254207.107.255.25532,766
217207.108.0.0/17207.108.0.1 to 207.108.127.254207.108.127.25532,766
218207.108.128.0/17207.108.128.1 to 207.108.255.254207.108.255.25532,766
219207.109.0.0/17207.109.0.1 to 207.109.127.254207.109.127.25532,766
220207.109.128.0/17207.109.128.1 to 207.109.255.254207.109.255.25532,766
221207.110.0.0/17207.110.0.1 to 207.110.127.254207.110.127.25532,766
222207.110.128.0/17207.110.128.1 to 207.110.255.254207.110.255.25532,766
223207.111.0.0/17207.111.0.1 to 207.111.127.254207.111.127.25532,766
224207.111.128.0/17207.111.128.1 to 207.111.255.254207.111.255.25532,766
225207.112.0.0/17207.112.0.1 to 207.112.127.254207.112.127.25532,766
226207.112.128.0/17207.112.128.1 to 207.112.255.254207.112.255.25532,766
227207.113.0.0/17207.113.0.1 to 207.113.127.254207.113.127.25532,766
228207.113.128.0/17207.113.128.1 to 207.113.255.254207.113.255.25532,766
229207.114.0.0/17207.114.0.1 to 207.114.127.254207.114.127.25532,766
230207.114.128.0/17207.114.128.1 to 207.114.255.254207.114.255.25532,766
231207.115.0.0/17207.115.0.1 to 207.115.127.254207.115.127.25532,766
232207.115.128.0/17207.115.128.1 to 207.115.255.254207.115.255.25532,766
233207.116.0.0/17207.116.0.1 to 207.116.127.254207.116.127.25532,766
234207.116.128.0/17207.116.128.1 to 207.116.255.254207.116.255.25532,766
235207.117.0.0/17207.117.0.1 to 207.117.127.254207.117.127.25532,766
236207.117.128.0/17207.117.128.1 to 207.117.255.254207.117.255.25532,766
237207.118.0.0/17207.118.0.1 to 207.118.127.254207.118.127.25532,766
238207.118.128.0/17207.118.128.1 to 207.118.255.254207.118.255.25532,766
239207.119.0.0/17207.119.0.1 to 207.119.127.254207.119.127.25532,766
240207.119.128.0/17207.119.128.1 to 207.119.255.254207.119.255.25532,766
241207.120.0.0/17207.120.0.1 to 207.120.127.254207.120.127.25532,766
242207.120.128.0/17207.120.128.1 to 207.120.255.254207.120.255.25532,766
243207.121.0.0/17207.121.0.1 to 207.121.127.254207.121.127.25532,766
244207.121.128.0/17207.121.128.1 to 207.121.255.254207.121.255.25532,766
245207.122.0.0/17207.122.0.1 to 207.122.127.254207.122.127.25532,766
246207.122.128.0/17207.122.128.1 to 207.122.255.254207.122.255.25532,766
247207.123.0.0/17207.123.0.1 to 207.123.127.254207.123.127.25532,766
248207.123.128.0/17207.123.128.1 to 207.123.255.254207.123.255.25532,766
249207.124.0.0/17207.124.0.1 to 207.124.127.254207.124.127.25532,766
250207.124.128.0/17207.124.128.1 to 207.124.255.254207.124.255.25532,766
251207.125.0.0/17207.125.0.1 to 207.125.127.254207.125.127.25532,766
252207.125.128.0/17207.125.128.1 to 207.125.255.254207.125.255.25532,766
253207.126.0.0/17207.126.0.1 to 207.126.127.254207.126.127.25532,766
254207.126.128.0/17207.126.128.1 to 207.126.255.254207.126.255.25532,766
255207.127.0.0/17207.127.0.1 to 207.127.127.254207.127.127.25532,766
256207.127.128.0/17207.127.128.1 to 207.127.255.254207.127.255.25532,766

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.