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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.

Network166.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
166.0.0.0
Broadcast address
167.255.255.255
First usable
166.0.0.1
Last usable
167.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex A6000000 · Integer 2785017856 to 2818572287
Reverse DNS zones
166.in-addr.arpa
167.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100110.00000000.00000000.00000000166.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10100110.00000000.00000000.00000000166.0.0.0
Broadcast10100111.11111111.11111111.11111111167.255.255.255
Split into smaller subnets/17
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

166.0.0.0/7 makes 1,024 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1166.0.0.0/17166.0.0.1 to 166.0.127.254166.0.127.25532,766
2166.0.128.0/17166.0.128.1 to 166.0.255.254166.0.255.25532,766
3166.1.0.0/17166.1.0.1 to 166.1.127.254166.1.127.25532,766
4166.1.128.0/17166.1.128.1 to 166.1.255.254166.1.255.25532,766
5166.2.0.0/17166.2.0.1 to 166.2.127.254166.2.127.25532,766
6166.2.128.0/17166.2.128.1 to 166.2.255.254166.2.255.25532,766
7166.3.0.0/17166.3.0.1 to 166.3.127.254166.3.127.25532,766
8166.3.128.0/17166.3.128.1 to 166.3.255.254166.3.255.25532,766
9166.4.0.0/17166.4.0.1 to 166.4.127.254166.4.127.25532,766
10166.4.128.0/17166.4.128.1 to 166.4.255.254166.4.255.25532,766
11166.5.0.0/17166.5.0.1 to 166.5.127.254166.5.127.25532,766
12166.5.128.0/17166.5.128.1 to 166.5.255.254166.5.255.25532,766
13166.6.0.0/17166.6.0.1 to 166.6.127.254166.6.127.25532,766
14166.6.128.0/17166.6.128.1 to 166.6.255.254166.6.255.25532,766
15166.7.0.0/17166.7.0.1 to 166.7.127.254166.7.127.25532,766
16166.7.128.0/17166.7.128.1 to 166.7.255.254166.7.255.25532,766
17166.8.0.0/17166.8.0.1 to 166.8.127.254166.8.127.25532,766
18166.8.128.0/17166.8.128.1 to 166.8.255.254166.8.255.25532,766
19166.9.0.0/17166.9.0.1 to 166.9.127.254166.9.127.25532,766
20166.9.128.0/17166.9.128.1 to 166.9.255.254166.9.255.25532,766
21166.10.0.0/17166.10.0.1 to 166.10.127.254166.10.127.25532,766
22166.10.128.0/17166.10.128.1 to 166.10.255.254166.10.255.25532,766
23166.11.0.0/17166.11.0.1 to 166.11.127.254166.11.127.25532,766
24166.11.128.0/17166.11.128.1 to 166.11.255.254166.11.255.25532,766
25166.12.0.0/17166.12.0.1 to 166.12.127.254166.12.127.25532,766
26166.12.128.0/17166.12.128.1 to 166.12.255.254166.12.255.25532,766
27166.13.0.0/17166.13.0.1 to 166.13.127.254166.13.127.25532,766
28166.13.128.0/17166.13.128.1 to 166.13.255.254166.13.255.25532,766
29166.14.0.0/17166.14.0.1 to 166.14.127.254166.14.127.25532,766
30166.14.128.0/17166.14.128.1 to 166.14.255.254166.14.255.25532,766
31166.15.0.0/17166.15.0.1 to 166.15.127.254166.15.127.25532,766
32166.15.128.0/17166.15.128.1 to 166.15.255.254166.15.255.25532,766
33166.16.0.0/17166.16.0.1 to 166.16.127.254166.16.127.25532,766
34166.16.128.0/17166.16.128.1 to 166.16.255.254166.16.255.25532,766
35166.17.0.0/17166.17.0.1 to 166.17.127.254166.17.127.25532,766
36166.17.128.0/17166.17.128.1 to 166.17.255.254166.17.255.25532,766
37166.18.0.0/17166.18.0.1 to 166.18.127.254166.18.127.25532,766
38166.18.128.0/17166.18.128.1 to 166.18.255.254166.18.255.25532,766
39166.19.0.0/17166.19.0.1 to 166.19.127.254166.19.127.25532,766
40166.19.128.0/17166.19.128.1 to 166.19.255.254166.19.255.25532,766
41166.20.0.0/17166.20.0.1 to 166.20.127.254166.20.127.25532,766
42166.20.128.0/17166.20.128.1 to 166.20.255.254166.20.255.25532,766
43166.21.0.0/17166.21.0.1 to 166.21.127.254166.21.127.25532,766
44166.21.128.0/17166.21.128.1 to 166.21.255.254166.21.255.25532,766
45166.22.0.0/17166.22.0.1 to 166.22.127.254166.22.127.25532,766
46166.22.128.0/17166.22.128.1 to 166.22.255.254166.22.255.25532,766
47166.23.0.0/17166.23.0.1 to 166.23.127.254166.23.127.25532,766
48166.23.128.0/17166.23.128.1 to 166.23.255.254166.23.255.25532,766
49166.24.0.0/17166.24.0.1 to 166.24.127.254166.24.127.25532,766
50166.24.128.0/17166.24.128.1 to 166.24.255.254166.24.255.25532,766
51166.25.0.0/17166.25.0.1 to 166.25.127.254166.25.127.25532,766
52166.25.128.0/17166.25.128.1 to 166.25.255.254166.25.255.25532,766
53166.26.0.0/17166.26.0.1 to 166.26.127.254166.26.127.25532,766
54166.26.128.0/17166.26.128.1 to 166.26.255.254166.26.255.25532,766
55166.27.0.0/17166.27.0.1 to 166.27.127.254166.27.127.25532,766
56166.27.128.0/17166.27.128.1 to 166.27.255.254166.27.255.25532,766
57166.28.0.0/17166.28.0.1 to 166.28.127.254166.28.127.25532,766
58166.28.128.0/17166.28.128.1 to 166.28.255.254166.28.255.25532,766
59166.29.0.0/17166.29.0.1 to 166.29.127.254166.29.127.25532,766
60166.29.128.0/17166.29.128.1 to 166.29.255.254166.29.255.25532,766
61166.30.0.0/17166.30.0.1 to 166.30.127.254166.30.127.25532,766
62166.30.128.0/17166.30.128.1 to 166.30.255.254166.30.255.25532,766
63166.31.0.0/17166.31.0.1 to 166.31.127.254166.31.127.25532,766
64166.31.128.0/17166.31.128.1 to 166.31.255.254166.31.255.25532,766
65166.32.0.0/17166.32.0.1 to 166.32.127.254166.32.127.25532,766
66166.32.128.0/17166.32.128.1 to 166.32.255.254166.32.255.25532,766
67166.33.0.0/17166.33.0.1 to 166.33.127.254166.33.127.25532,766
68166.33.128.0/17166.33.128.1 to 166.33.255.254166.33.255.25532,766
69166.34.0.0/17166.34.0.1 to 166.34.127.254166.34.127.25532,766
70166.34.128.0/17166.34.128.1 to 166.34.255.254166.34.255.25532,766
71166.35.0.0/17166.35.0.1 to 166.35.127.254166.35.127.25532,766
72166.35.128.0/17166.35.128.1 to 166.35.255.254166.35.255.25532,766
73166.36.0.0/17166.36.0.1 to 166.36.127.254166.36.127.25532,766
74166.36.128.0/17166.36.128.1 to 166.36.255.254166.36.255.25532,766
75166.37.0.0/17166.37.0.1 to 166.37.127.254166.37.127.25532,766
76166.37.128.0/17166.37.128.1 to 166.37.255.254166.37.255.25532,766
77166.38.0.0/17166.38.0.1 to 166.38.127.254166.38.127.25532,766
78166.38.128.0/17166.38.128.1 to 166.38.255.254166.38.255.25532,766
79166.39.0.0/17166.39.0.1 to 166.39.127.254166.39.127.25532,766
80166.39.128.0/17166.39.128.1 to 166.39.255.254166.39.255.25532,766
81166.40.0.0/17166.40.0.1 to 166.40.127.254166.40.127.25532,766
82166.40.128.0/17166.40.128.1 to 166.40.255.254166.40.255.25532,766
83166.41.0.0/17166.41.0.1 to 166.41.127.254166.41.127.25532,766
84166.41.128.0/17166.41.128.1 to 166.41.255.254166.41.255.25532,766
85166.42.0.0/17166.42.0.1 to 166.42.127.254166.42.127.25532,766
86166.42.128.0/17166.42.128.1 to 166.42.255.254166.42.255.25532,766
87166.43.0.0/17166.43.0.1 to 166.43.127.254166.43.127.25532,766
88166.43.128.0/17166.43.128.1 to 166.43.255.254166.43.255.25532,766
89166.44.0.0/17166.44.0.1 to 166.44.127.254166.44.127.25532,766
90166.44.128.0/17166.44.128.1 to 166.44.255.254166.44.255.25532,766
91166.45.0.0/17166.45.0.1 to 166.45.127.254166.45.127.25532,766
92166.45.128.0/17166.45.128.1 to 166.45.255.254166.45.255.25532,766
93166.46.0.0/17166.46.0.1 to 166.46.127.254166.46.127.25532,766
94166.46.128.0/17166.46.128.1 to 166.46.255.254166.46.255.25532,766
95166.47.0.0/17166.47.0.1 to 166.47.127.254166.47.127.25532,766
96166.47.128.0/17166.47.128.1 to 166.47.255.254166.47.255.25532,766
97166.48.0.0/17166.48.0.1 to 166.48.127.254166.48.127.25532,766
98166.48.128.0/17166.48.128.1 to 166.48.255.254166.48.255.25532,766
99166.49.0.0/17166.49.0.1 to 166.49.127.254166.49.127.25532,766
100166.49.128.0/17166.49.128.1 to 166.49.255.254166.49.255.25532,766
101166.50.0.0/17166.50.0.1 to 166.50.127.254166.50.127.25532,766
102166.50.128.0/17166.50.128.1 to 166.50.255.254166.50.255.25532,766
103166.51.0.0/17166.51.0.1 to 166.51.127.254166.51.127.25532,766
104166.51.128.0/17166.51.128.1 to 166.51.255.254166.51.255.25532,766
105166.52.0.0/17166.52.0.1 to 166.52.127.254166.52.127.25532,766
106166.52.128.0/17166.52.128.1 to 166.52.255.254166.52.255.25532,766
107166.53.0.0/17166.53.0.1 to 166.53.127.254166.53.127.25532,766
108166.53.128.0/17166.53.128.1 to 166.53.255.254166.53.255.25532,766
109166.54.0.0/17166.54.0.1 to 166.54.127.254166.54.127.25532,766
110166.54.128.0/17166.54.128.1 to 166.54.255.254166.54.255.25532,766
111166.55.0.0/17166.55.0.1 to 166.55.127.254166.55.127.25532,766
112166.55.128.0/17166.55.128.1 to 166.55.255.254166.55.255.25532,766
113166.56.0.0/17166.56.0.1 to 166.56.127.254166.56.127.25532,766
114166.56.128.0/17166.56.128.1 to 166.56.255.254166.56.255.25532,766
115166.57.0.0/17166.57.0.1 to 166.57.127.254166.57.127.25532,766
116166.57.128.0/17166.57.128.1 to 166.57.255.254166.57.255.25532,766
117166.58.0.0/17166.58.0.1 to 166.58.127.254166.58.127.25532,766
118166.58.128.0/17166.58.128.1 to 166.58.255.254166.58.255.25532,766
119166.59.0.0/17166.59.0.1 to 166.59.127.254166.59.127.25532,766
120166.59.128.0/17166.59.128.1 to 166.59.255.254166.59.255.25532,766
121166.60.0.0/17166.60.0.1 to 166.60.127.254166.60.127.25532,766
122166.60.128.0/17166.60.128.1 to 166.60.255.254166.60.255.25532,766
123166.61.0.0/17166.61.0.1 to 166.61.127.254166.61.127.25532,766
124166.61.128.0/17166.61.128.1 to 166.61.255.254166.61.255.25532,766
125166.62.0.0/17166.62.0.1 to 166.62.127.254166.62.127.25532,766
126166.62.128.0/17166.62.128.1 to 166.62.255.254166.62.255.25532,766
127166.63.0.0/17166.63.0.1 to 166.63.127.254166.63.127.25532,766
128166.63.128.0/17166.63.128.1 to 166.63.255.254166.63.255.25532,766
129166.64.0.0/17166.64.0.1 to 166.64.127.254166.64.127.25532,766
130166.64.128.0/17166.64.128.1 to 166.64.255.254166.64.255.25532,766
131166.65.0.0/17166.65.0.1 to 166.65.127.254166.65.127.25532,766
132166.65.128.0/17166.65.128.1 to 166.65.255.254166.65.255.25532,766
133166.66.0.0/17166.66.0.1 to 166.66.127.254166.66.127.25532,766
134166.66.128.0/17166.66.128.1 to 166.66.255.254166.66.255.25532,766
135166.67.0.0/17166.67.0.1 to 166.67.127.254166.67.127.25532,766
136166.67.128.0/17166.67.128.1 to 166.67.255.254166.67.255.25532,766
137166.68.0.0/17166.68.0.1 to 166.68.127.254166.68.127.25532,766
138166.68.128.0/17166.68.128.1 to 166.68.255.254166.68.255.25532,766
139166.69.0.0/17166.69.0.1 to 166.69.127.254166.69.127.25532,766
140166.69.128.0/17166.69.128.1 to 166.69.255.254166.69.255.25532,766
141166.70.0.0/17166.70.0.1 to 166.70.127.254166.70.127.25532,766
142166.70.128.0/17166.70.128.1 to 166.70.255.254166.70.255.25532,766
143166.71.0.0/17166.71.0.1 to 166.71.127.254166.71.127.25532,766
144166.71.128.0/17166.71.128.1 to 166.71.255.254166.71.255.25532,766
145166.72.0.0/17166.72.0.1 to 166.72.127.254166.72.127.25532,766
146166.72.128.0/17166.72.128.1 to 166.72.255.254166.72.255.25532,766
147166.73.0.0/17166.73.0.1 to 166.73.127.254166.73.127.25532,766
148166.73.128.0/17166.73.128.1 to 166.73.255.254166.73.255.25532,766
149166.74.0.0/17166.74.0.1 to 166.74.127.254166.74.127.25532,766
150166.74.128.0/17166.74.128.1 to 166.74.255.254166.74.255.25532,766
151166.75.0.0/17166.75.0.1 to 166.75.127.254166.75.127.25532,766
152166.75.128.0/17166.75.128.1 to 166.75.255.254166.75.255.25532,766
153166.76.0.0/17166.76.0.1 to 166.76.127.254166.76.127.25532,766
154166.76.128.0/17166.76.128.1 to 166.76.255.254166.76.255.25532,766
155166.77.0.0/17166.77.0.1 to 166.77.127.254166.77.127.25532,766
156166.77.128.0/17166.77.128.1 to 166.77.255.254166.77.255.25532,766
157166.78.0.0/17166.78.0.1 to 166.78.127.254166.78.127.25532,766
158166.78.128.0/17166.78.128.1 to 166.78.255.254166.78.255.25532,766
159166.79.0.0/17166.79.0.1 to 166.79.127.254166.79.127.25532,766
160166.79.128.0/17166.79.128.1 to 166.79.255.254166.79.255.25532,766
161166.80.0.0/17166.80.0.1 to 166.80.127.254166.80.127.25532,766
162166.80.128.0/17166.80.128.1 to 166.80.255.254166.80.255.25532,766
163166.81.0.0/17166.81.0.1 to 166.81.127.254166.81.127.25532,766
164166.81.128.0/17166.81.128.1 to 166.81.255.254166.81.255.25532,766
165166.82.0.0/17166.82.0.1 to 166.82.127.254166.82.127.25532,766
166166.82.128.0/17166.82.128.1 to 166.82.255.254166.82.255.25532,766
167166.83.0.0/17166.83.0.1 to 166.83.127.254166.83.127.25532,766
168166.83.128.0/17166.83.128.1 to 166.83.255.254166.83.255.25532,766
169166.84.0.0/17166.84.0.1 to 166.84.127.254166.84.127.25532,766
170166.84.128.0/17166.84.128.1 to 166.84.255.254166.84.255.25532,766
171166.85.0.0/17166.85.0.1 to 166.85.127.254166.85.127.25532,766
172166.85.128.0/17166.85.128.1 to 166.85.255.254166.85.255.25532,766
173166.86.0.0/17166.86.0.1 to 166.86.127.254166.86.127.25532,766
174166.86.128.0/17166.86.128.1 to 166.86.255.254166.86.255.25532,766
175166.87.0.0/17166.87.0.1 to 166.87.127.254166.87.127.25532,766
176166.87.128.0/17166.87.128.1 to 166.87.255.254166.87.255.25532,766
177166.88.0.0/17166.88.0.1 to 166.88.127.254166.88.127.25532,766
178166.88.128.0/17166.88.128.1 to 166.88.255.254166.88.255.25532,766
179166.89.0.0/17166.89.0.1 to 166.89.127.254166.89.127.25532,766
180166.89.128.0/17166.89.128.1 to 166.89.255.254166.89.255.25532,766
181166.90.0.0/17166.90.0.1 to 166.90.127.254166.90.127.25532,766
182166.90.128.0/17166.90.128.1 to 166.90.255.254166.90.255.25532,766
183166.91.0.0/17166.91.0.1 to 166.91.127.254166.91.127.25532,766
184166.91.128.0/17166.91.128.1 to 166.91.255.254166.91.255.25532,766
185166.92.0.0/17166.92.0.1 to 166.92.127.254166.92.127.25532,766
186166.92.128.0/17166.92.128.1 to 166.92.255.254166.92.255.25532,766
187166.93.0.0/17166.93.0.1 to 166.93.127.254166.93.127.25532,766
188166.93.128.0/17166.93.128.1 to 166.93.255.254166.93.255.25532,766
189166.94.0.0/17166.94.0.1 to 166.94.127.254166.94.127.25532,766
190166.94.128.0/17166.94.128.1 to 166.94.255.254166.94.255.25532,766
191166.95.0.0/17166.95.0.1 to 166.95.127.254166.95.127.25532,766
192166.95.128.0/17166.95.128.1 to 166.95.255.254166.95.255.25532,766
193166.96.0.0/17166.96.0.1 to 166.96.127.254166.96.127.25532,766
194166.96.128.0/17166.96.128.1 to 166.96.255.254166.96.255.25532,766
195166.97.0.0/17166.97.0.1 to 166.97.127.254166.97.127.25532,766
196166.97.128.0/17166.97.128.1 to 166.97.255.254166.97.255.25532,766
197166.98.0.0/17166.98.0.1 to 166.98.127.254166.98.127.25532,766
198166.98.128.0/17166.98.128.1 to 166.98.255.254166.98.255.25532,766
199166.99.0.0/17166.99.0.1 to 166.99.127.254166.99.127.25532,766
200166.99.128.0/17166.99.128.1 to 166.99.255.254166.99.255.25532,766
201166.100.0.0/17166.100.0.1 to 166.100.127.254166.100.127.25532,766
202166.100.128.0/17166.100.128.1 to 166.100.255.254166.100.255.25532,766
203166.101.0.0/17166.101.0.1 to 166.101.127.254166.101.127.25532,766
204166.101.128.0/17166.101.128.1 to 166.101.255.254166.101.255.25532,766
205166.102.0.0/17166.102.0.1 to 166.102.127.254166.102.127.25532,766
206166.102.128.0/17166.102.128.1 to 166.102.255.254166.102.255.25532,766
207166.103.0.0/17166.103.0.1 to 166.103.127.254166.103.127.25532,766
208166.103.128.0/17166.103.128.1 to 166.103.255.254166.103.255.25532,766
209166.104.0.0/17166.104.0.1 to 166.104.127.254166.104.127.25532,766
210166.104.128.0/17166.104.128.1 to 166.104.255.254166.104.255.25532,766
211166.105.0.0/17166.105.0.1 to 166.105.127.254166.105.127.25532,766
212166.105.128.0/17166.105.128.1 to 166.105.255.254166.105.255.25532,766
213166.106.0.0/17166.106.0.1 to 166.106.127.254166.106.127.25532,766
214166.106.128.0/17166.106.128.1 to 166.106.255.254166.106.255.25532,766
215166.107.0.0/17166.107.0.1 to 166.107.127.254166.107.127.25532,766
216166.107.128.0/17166.107.128.1 to 166.107.255.254166.107.255.25532,766
217166.108.0.0/17166.108.0.1 to 166.108.127.254166.108.127.25532,766
218166.108.128.0/17166.108.128.1 to 166.108.255.254166.108.255.25532,766
219166.109.0.0/17166.109.0.1 to 166.109.127.254166.109.127.25532,766
220166.109.128.0/17166.109.128.1 to 166.109.255.254166.109.255.25532,766
221166.110.0.0/17166.110.0.1 to 166.110.127.254166.110.127.25532,766
222166.110.128.0/17166.110.128.1 to 166.110.255.254166.110.255.25532,766
223166.111.0.0/17166.111.0.1 to 166.111.127.254166.111.127.25532,766
224166.111.128.0/17166.111.128.1 to 166.111.255.254166.111.255.25532,766
225166.112.0.0/17166.112.0.1 to 166.112.127.254166.112.127.25532,766
226166.112.128.0/17166.112.128.1 to 166.112.255.254166.112.255.25532,766
227166.113.0.0/17166.113.0.1 to 166.113.127.254166.113.127.25532,766
228166.113.128.0/17166.113.128.1 to 166.113.255.254166.113.255.25532,766
229166.114.0.0/17166.114.0.1 to 166.114.127.254166.114.127.25532,766
230166.114.128.0/17166.114.128.1 to 166.114.255.254166.114.255.25532,766
231166.115.0.0/17166.115.0.1 to 166.115.127.254166.115.127.25532,766
232166.115.128.0/17166.115.128.1 to 166.115.255.254166.115.255.25532,766
233166.116.0.0/17166.116.0.1 to 166.116.127.254166.116.127.25532,766
234166.116.128.0/17166.116.128.1 to 166.116.255.254166.116.255.25532,766
235166.117.0.0/17166.117.0.1 to 166.117.127.254166.117.127.25532,766
236166.117.128.0/17166.117.128.1 to 166.117.255.254166.117.255.25532,766
237166.118.0.0/17166.118.0.1 to 166.118.127.254166.118.127.25532,766
238166.118.128.0/17166.118.128.1 to 166.118.255.254166.118.255.25532,766
239166.119.0.0/17166.119.0.1 to 166.119.127.254166.119.127.25532,766
240166.119.128.0/17166.119.128.1 to 166.119.255.254166.119.255.25532,766
241166.120.0.0/17166.120.0.1 to 166.120.127.254166.120.127.25532,766
242166.120.128.0/17166.120.128.1 to 166.120.255.254166.120.255.25532,766
243166.121.0.0/17166.121.0.1 to 166.121.127.254166.121.127.25532,766
244166.121.128.0/17166.121.128.1 to 166.121.255.254166.121.255.25532,766
245166.122.0.0/17166.122.0.1 to 166.122.127.254166.122.127.25532,766
246166.122.128.0/17166.122.128.1 to 166.122.255.254166.122.255.25532,766
247166.123.0.0/17166.123.0.1 to 166.123.127.254166.123.127.25532,766
248166.123.128.0/17166.123.128.1 to 166.123.255.254166.123.255.25532,766
249166.124.0.0/17166.124.0.1 to 166.124.127.254166.124.127.25532,766
250166.124.128.0/17166.124.128.1 to 166.124.255.254166.124.255.25532,766
251166.125.0.0/17166.125.0.1 to 166.125.127.254166.125.127.25532,766
252166.125.128.0/17166.125.128.1 to 166.125.255.254166.125.255.25532,766
253166.126.0.0/17166.126.0.1 to 166.126.127.254166.126.127.25532,766
254166.126.128.0/17166.126.128.1 to 166.126.255.254166.126.255.25532,766
255166.127.0.0/17166.127.0.1 to 166.127.127.254166.127.127.25532,766
256166.127.128.0/17166.127.128.1 to 166.127.255.254166.127.255.25532,766

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.