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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.

Network166.2.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
166.2.0.0
Broadcast address
166.2.127.255
First usable
166.2.0.1
Last usable
166.2.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex A6020000 · Integer 2785148928 to 2785181695
Reverse DNS zones
0.2.166.in-addr.arpa
1.2.166.in-addr.arpa
2.2.166.in-addr.arpa
3.2.166.in-addr.arpa
4.2.166.in-addr.arpa
5.2.166.in-addr.arpa
6.2.166.in-addr.arpa
7.2.166.in-addr.arpa
8.2.166.in-addr.arpa
9.2.166.in-addr.arpa
10.2.166.in-addr.arpa
11.2.166.in-addr.arpa
12.2.166.in-addr.arpa
13.2.166.in-addr.arpa
14.2.166.in-addr.arpa
15.2.166.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100110.00000010.00000000.00000000166.2.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10100110.00000010.00000000.00000000166.2.0.0
Broadcast10100110.00000010.01111111.11111111166.2.127.255
Split into smaller subnets/25
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

166.2.0.0/17 makes 256 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1166.2.0.0/25166.2.0.1 to 166.2.0.126166.2.0.127126
2166.2.0.128/25166.2.0.129 to 166.2.0.254166.2.0.255126
3166.2.1.0/25166.2.1.1 to 166.2.1.126166.2.1.127126
4166.2.1.128/25166.2.1.129 to 166.2.1.254166.2.1.255126
5166.2.2.0/25166.2.2.1 to 166.2.2.126166.2.2.127126
6166.2.2.128/25166.2.2.129 to 166.2.2.254166.2.2.255126
7166.2.3.0/25166.2.3.1 to 166.2.3.126166.2.3.127126
8166.2.3.128/25166.2.3.129 to 166.2.3.254166.2.3.255126
9166.2.4.0/25166.2.4.1 to 166.2.4.126166.2.4.127126
10166.2.4.128/25166.2.4.129 to 166.2.4.254166.2.4.255126
11166.2.5.0/25166.2.5.1 to 166.2.5.126166.2.5.127126
12166.2.5.128/25166.2.5.129 to 166.2.5.254166.2.5.255126
13166.2.6.0/25166.2.6.1 to 166.2.6.126166.2.6.127126
14166.2.6.128/25166.2.6.129 to 166.2.6.254166.2.6.255126
15166.2.7.0/25166.2.7.1 to 166.2.7.126166.2.7.127126
16166.2.7.128/25166.2.7.129 to 166.2.7.254166.2.7.255126
17166.2.8.0/25166.2.8.1 to 166.2.8.126166.2.8.127126
18166.2.8.128/25166.2.8.129 to 166.2.8.254166.2.8.255126
19166.2.9.0/25166.2.9.1 to 166.2.9.126166.2.9.127126
20166.2.9.128/25166.2.9.129 to 166.2.9.254166.2.9.255126
21166.2.10.0/25166.2.10.1 to 166.2.10.126166.2.10.127126
22166.2.10.128/25166.2.10.129 to 166.2.10.254166.2.10.255126
23166.2.11.0/25166.2.11.1 to 166.2.11.126166.2.11.127126
24166.2.11.128/25166.2.11.129 to 166.2.11.254166.2.11.255126
25166.2.12.0/25166.2.12.1 to 166.2.12.126166.2.12.127126
26166.2.12.128/25166.2.12.129 to 166.2.12.254166.2.12.255126
27166.2.13.0/25166.2.13.1 to 166.2.13.126166.2.13.127126
28166.2.13.128/25166.2.13.129 to 166.2.13.254166.2.13.255126
29166.2.14.0/25166.2.14.1 to 166.2.14.126166.2.14.127126
30166.2.14.128/25166.2.14.129 to 166.2.14.254166.2.14.255126
31166.2.15.0/25166.2.15.1 to 166.2.15.126166.2.15.127126
32166.2.15.128/25166.2.15.129 to 166.2.15.254166.2.15.255126
33166.2.16.0/25166.2.16.1 to 166.2.16.126166.2.16.127126
34166.2.16.128/25166.2.16.129 to 166.2.16.254166.2.16.255126
35166.2.17.0/25166.2.17.1 to 166.2.17.126166.2.17.127126
36166.2.17.128/25166.2.17.129 to 166.2.17.254166.2.17.255126
37166.2.18.0/25166.2.18.1 to 166.2.18.126166.2.18.127126
38166.2.18.128/25166.2.18.129 to 166.2.18.254166.2.18.255126
39166.2.19.0/25166.2.19.1 to 166.2.19.126166.2.19.127126
40166.2.19.128/25166.2.19.129 to 166.2.19.254166.2.19.255126
41166.2.20.0/25166.2.20.1 to 166.2.20.126166.2.20.127126
42166.2.20.128/25166.2.20.129 to 166.2.20.254166.2.20.255126
43166.2.21.0/25166.2.21.1 to 166.2.21.126166.2.21.127126
44166.2.21.128/25166.2.21.129 to 166.2.21.254166.2.21.255126
45166.2.22.0/25166.2.22.1 to 166.2.22.126166.2.22.127126
46166.2.22.128/25166.2.22.129 to 166.2.22.254166.2.22.255126
47166.2.23.0/25166.2.23.1 to 166.2.23.126166.2.23.127126
48166.2.23.128/25166.2.23.129 to 166.2.23.254166.2.23.255126
49166.2.24.0/25166.2.24.1 to 166.2.24.126166.2.24.127126
50166.2.24.128/25166.2.24.129 to 166.2.24.254166.2.24.255126
51166.2.25.0/25166.2.25.1 to 166.2.25.126166.2.25.127126
52166.2.25.128/25166.2.25.129 to 166.2.25.254166.2.25.255126
53166.2.26.0/25166.2.26.1 to 166.2.26.126166.2.26.127126
54166.2.26.128/25166.2.26.129 to 166.2.26.254166.2.26.255126
55166.2.27.0/25166.2.27.1 to 166.2.27.126166.2.27.127126
56166.2.27.128/25166.2.27.129 to 166.2.27.254166.2.27.255126
57166.2.28.0/25166.2.28.1 to 166.2.28.126166.2.28.127126
58166.2.28.128/25166.2.28.129 to 166.2.28.254166.2.28.255126
59166.2.29.0/25166.2.29.1 to 166.2.29.126166.2.29.127126
60166.2.29.128/25166.2.29.129 to 166.2.29.254166.2.29.255126
61166.2.30.0/25166.2.30.1 to 166.2.30.126166.2.30.127126
62166.2.30.128/25166.2.30.129 to 166.2.30.254166.2.30.255126
63166.2.31.0/25166.2.31.1 to 166.2.31.126166.2.31.127126
64166.2.31.128/25166.2.31.129 to 166.2.31.254166.2.31.255126
65166.2.32.0/25166.2.32.1 to 166.2.32.126166.2.32.127126
66166.2.32.128/25166.2.32.129 to 166.2.32.254166.2.32.255126
67166.2.33.0/25166.2.33.1 to 166.2.33.126166.2.33.127126
68166.2.33.128/25166.2.33.129 to 166.2.33.254166.2.33.255126
69166.2.34.0/25166.2.34.1 to 166.2.34.126166.2.34.127126
70166.2.34.128/25166.2.34.129 to 166.2.34.254166.2.34.255126
71166.2.35.0/25166.2.35.1 to 166.2.35.126166.2.35.127126
72166.2.35.128/25166.2.35.129 to 166.2.35.254166.2.35.255126
73166.2.36.0/25166.2.36.1 to 166.2.36.126166.2.36.127126
74166.2.36.128/25166.2.36.129 to 166.2.36.254166.2.36.255126
75166.2.37.0/25166.2.37.1 to 166.2.37.126166.2.37.127126
76166.2.37.128/25166.2.37.129 to 166.2.37.254166.2.37.255126
77166.2.38.0/25166.2.38.1 to 166.2.38.126166.2.38.127126
78166.2.38.128/25166.2.38.129 to 166.2.38.254166.2.38.255126
79166.2.39.0/25166.2.39.1 to 166.2.39.126166.2.39.127126
80166.2.39.128/25166.2.39.129 to 166.2.39.254166.2.39.255126
81166.2.40.0/25166.2.40.1 to 166.2.40.126166.2.40.127126
82166.2.40.128/25166.2.40.129 to 166.2.40.254166.2.40.255126
83166.2.41.0/25166.2.41.1 to 166.2.41.126166.2.41.127126
84166.2.41.128/25166.2.41.129 to 166.2.41.254166.2.41.255126
85166.2.42.0/25166.2.42.1 to 166.2.42.126166.2.42.127126
86166.2.42.128/25166.2.42.129 to 166.2.42.254166.2.42.255126
87166.2.43.0/25166.2.43.1 to 166.2.43.126166.2.43.127126
88166.2.43.128/25166.2.43.129 to 166.2.43.254166.2.43.255126
89166.2.44.0/25166.2.44.1 to 166.2.44.126166.2.44.127126
90166.2.44.128/25166.2.44.129 to 166.2.44.254166.2.44.255126
91166.2.45.0/25166.2.45.1 to 166.2.45.126166.2.45.127126
92166.2.45.128/25166.2.45.129 to 166.2.45.254166.2.45.255126
93166.2.46.0/25166.2.46.1 to 166.2.46.126166.2.46.127126
94166.2.46.128/25166.2.46.129 to 166.2.46.254166.2.46.255126
95166.2.47.0/25166.2.47.1 to 166.2.47.126166.2.47.127126
96166.2.47.128/25166.2.47.129 to 166.2.47.254166.2.47.255126
97166.2.48.0/25166.2.48.1 to 166.2.48.126166.2.48.127126
98166.2.48.128/25166.2.48.129 to 166.2.48.254166.2.48.255126
99166.2.49.0/25166.2.49.1 to 166.2.49.126166.2.49.127126
100166.2.49.128/25166.2.49.129 to 166.2.49.254166.2.49.255126
101166.2.50.0/25166.2.50.1 to 166.2.50.126166.2.50.127126
102166.2.50.128/25166.2.50.129 to 166.2.50.254166.2.50.255126
103166.2.51.0/25166.2.51.1 to 166.2.51.126166.2.51.127126
104166.2.51.128/25166.2.51.129 to 166.2.51.254166.2.51.255126
105166.2.52.0/25166.2.52.1 to 166.2.52.126166.2.52.127126
106166.2.52.128/25166.2.52.129 to 166.2.52.254166.2.52.255126
107166.2.53.0/25166.2.53.1 to 166.2.53.126166.2.53.127126
108166.2.53.128/25166.2.53.129 to 166.2.53.254166.2.53.255126
109166.2.54.0/25166.2.54.1 to 166.2.54.126166.2.54.127126
110166.2.54.128/25166.2.54.129 to 166.2.54.254166.2.54.255126
111166.2.55.0/25166.2.55.1 to 166.2.55.126166.2.55.127126
112166.2.55.128/25166.2.55.129 to 166.2.55.254166.2.55.255126
113166.2.56.0/25166.2.56.1 to 166.2.56.126166.2.56.127126
114166.2.56.128/25166.2.56.129 to 166.2.56.254166.2.56.255126
115166.2.57.0/25166.2.57.1 to 166.2.57.126166.2.57.127126
116166.2.57.128/25166.2.57.129 to 166.2.57.254166.2.57.255126
117166.2.58.0/25166.2.58.1 to 166.2.58.126166.2.58.127126
118166.2.58.128/25166.2.58.129 to 166.2.58.254166.2.58.255126
119166.2.59.0/25166.2.59.1 to 166.2.59.126166.2.59.127126
120166.2.59.128/25166.2.59.129 to 166.2.59.254166.2.59.255126
121166.2.60.0/25166.2.60.1 to 166.2.60.126166.2.60.127126
122166.2.60.128/25166.2.60.129 to 166.2.60.254166.2.60.255126
123166.2.61.0/25166.2.61.1 to 166.2.61.126166.2.61.127126
124166.2.61.128/25166.2.61.129 to 166.2.61.254166.2.61.255126
125166.2.62.0/25166.2.62.1 to 166.2.62.126166.2.62.127126
126166.2.62.128/25166.2.62.129 to 166.2.62.254166.2.62.255126
127166.2.63.0/25166.2.63.1 to 166.2.63.126166.2.63.127126
128166.2.63.128/25166.2.63.129 to 166.2.63.254166.2.63.255126
129166.2.64.0/25166.2.64.1 to 166.2.64.126166.2.64.127126
130166.2.64.128/25166.2.64.129 to 166.2.64.254166.2.64.255126
131166.2.65.0/25166.2.65.1 to 166.2.65.126166.2.65.127126
132166.2.65.128/25166.2.65.129 to 166.2.65.254166.2.65.255126
133166.2.66.0/25166.2.66.1 to 166.2.66.126166.2.66.127126
134166.2.66.128/25166.2.66.129 to 166.2.66.254166.2.66.255126
135166.2.67.0/25166.2.67.1 to 166.2.67.126166.2.67.127126
136166.2.67.128/25166.2.67.129 to 166.2.67.254166.2.67.255126
137166.2.68.0/25166.2.68.1 to 166.2.68.126166.2.68.127126
138166.2.68.128/25166.2.68.129 to 166.2.68.254166.2.68.255126
139166.2.69.0/25166.2.69.1 to 166.2.69.126166.2.69.127126
140166.2.69.128/25166.2.69.129 to 166.2.69.254166.2.69.255126
141166.2.70.0/25166.2.70.1 to 166.2.70.126166.2.70.127126
142166.2.70.128/25166.2.70.129 to 166.2.70.254166.2.70.255126
143166.2.71.0/25166.2.71.1 to 166.2.71.126166.2.71.127126
144166.2.71.128/25166.2.71.129 to 166.2.71.254166.2.71.255126
145166.2.72.0/25166.2.72.1 to 166.2.72.126166.2.72.127126
146166.2.72.128/25166.2.72.129 to 166.2.72.254166.2.72.255126
147166.2.73.0/25166.2.73.1 to 166.2.73.126166.2.73.127126
148166.2.73.128/25166.2.73.129 to 166.2.73.254166.2.73.255126
149166.2.74.0/25166.2.74.1 to 166.2.74.126166.2.74.127126
150166.2.74.128/25166.2.74.129 to 166.2.74.254166.2.74.255126
151166.2.75.0/25166.2.75.1 to 166.2.75.126166.2.75.127126
152166.2.75.128/25166.2.75.129 to 166.2.75.254166.2.75.255126
153166.2.76.0/25166.2.76.1 to 166.2.76.126166.2.76.127126
154166.2.76.128/25166.2.76.129 to 166.2.76.254166.2.76.255126
155166.2.77.0/25166.2.77.1 to 166.2.77.126166.2.77.127126
156166.2.77.128/25166.2.77.129 to 166.2.77.254166.2.77.255126
157166.2.78.0/25166.2.78.1 to 166.2.78.126166.2.78.127126
158166.2.78.128/25166.2.78.129 to 166.2.78.254166.2.78.255126
159166.2.79.0/25166.2.79.1 to 166.2.79.126166.2.79.127126
160166.2.79.128/25166.2.79.129 to 166.2.79.254166.2.79.255126
161166.2.80.0/25166.2.80.1 to 166.2.80.126166.2.80.127126
162166.2.80.128/25166.2.80.129 to 166.2.80.254166.2.80.255126
163166.2.81.0/25166.2.81.1 to 166.2.81.126166.2.81.127126
164166.2.81.128/25166.2.81.129 to 166.2.81.254166.2.81.255126
165166.2.82.0/25166.2.82.1 to 166.2.82.126166.2.82.127126
166166.2.82.128/25166.2.82.129 to 166.2.82.254166.2.82.255126
167166.2.83.0/25166.2.83.1 to 166.2.83.126166.2.83.127126
168166.2.83.128/25166.2.83.129 to 166.2.83.254166.2.83.255126
169166.2.84.0/25166.2.84.1 to 166.2.84.126166.2.84.127126
170166.2.84.128/25166.2.84.129 to 166.2.84.254166.2.84.255126
171166.2.85.0/25166.2.85.1 to 166.2.85.126166.2.85.127126
172166.2.85.128/25166.2.85.129 to 166.2.85.254166.2.85.255126
173166.2.86.0/25166.2.86.1 to 166.2.86.126166.2.86.127126
174166.2.86.128/25166.2.86.129 to 166.2.86.254166.2.86.255126
175166.2.87.0/25166.2.87.1 to 166.2.87.126166.2.87.127126
176166.2.87.128/25166.2.87.129 to 166.2.87.254166.2.87.255126
177166.2.88.0/25166.2.88.1 to 166.2.88.126166.2.88.127126
178166.2.88.128/25166.2.88.129 to 166.2.88.254166.2.88.255126
179166.2.89.0/25166.2.89.1 to 166.2.89.126166.2.89.127126
180166.2.89.128/25166.2.89.129 to 166.2.89.254166.2.89.255126
181166.2.90.0/25166.2.90.1 to 166.2.90.126166.2.90.127126
182166.2.90.128/25166.2.90.129 to 166.2.90.254166.2.90.255126
183166.2.91.0/25166.2.91.1 to 166.2.91.126166.2.91.127126
184166.2.91.128/25166.2.91.129 to 166.2.91.254166.2.91.255126
185166.2.92.0/25166.2.92.1 to 166.2.92.126166.2.92.127126
186166.2.92.128/25166.2.92.129 to 166.2.92.254166.2.92.255126
187166.2.93.0/25166.2.93.1 to 166.2.93.126166.2.93.127126
188166.2.93.128/25166.2.93.129 to 166.2.93.254166.2.93.255126
189166.2.94.0/25166.2.94.1 to 166.2.94.126166.2.94.127126
190166.2.94.128/25166.2.94.129 to 166.2.94.254166.2.94.255126
191166.2.95.0/25166.2.95.1 to 166.2.95.126166.2.95.127126
192166.2.95.128/25166.2.95.129 to 166.2.95.254166.2.95.255126
193166.2.96.0/25166.2.96.1 to 166.2.96.126166.2.96.127126
194166.2.96.128/25166.2.96.129 to 166.2.96.254166.2.96.255126
195166.2.97.0/25166.2.97.1 to 166.2.97.126166.2.97.127126
196166.2.97.128/25166.2.97.129 to 166.2.97.254166.2.97.255126
197166.2.98.0/25166.2.98.1 to 166.2.98.126166.2.98.127126
198166.2.98.128/25166.2.98.129 to 166.2.98.254166.2.98.255126
199166.2.99.0/25166.2.99.1 to 166.2.99.126166.2.99.127126
200166.2.99.128/25166.2.99.129 to 166.2.99.254166.2.99.255126
201166.2.100.0/25166.2.100.1 to 166.2.100.126166.2.100.127126
202166.2.100.128/25166.2.100.129 to 166.2.100.254166.2.100.255126
203166.2.101.0/25166.2.101.1 to 166.2.101.126166.2.101.127126
204166.2.101.128/25166.2.101.129 to 166.2.101.254166.2.101.255126
205166.2.102.0/25166.2.102.1 to 166.2.102.126166.2.102.127126
206166.2.102.128/25166.2.102.129 to 166.2.102.254166.2.102.255126
207166.2.103.0/25166.2.103.1 to 166.2.103.126166.2.103.127126
208166.2.103.128/25166.2.103.129 to 166.2.103.254166.2.103.255126
209166.2.104.0/25166.2.104.1 to 166.2.104.126166.2.104.127126
210166.2.104.128/25166.2.104.129 to 166.2.104.254166.2.104.255126
211166.2.105.0/25166.2.105.1 to 166.2.105.126166.2.105.127126
212166.2.105.128/25166.2.105.129 to 166.2.105.254166.2.105.255126
213166.2.106.0/25166.2.106.1 to 166.2.106.126166.2.106.127126
214166.2.106.128/25166.2.106.129 to 166.2.106.254166.2.106.255126
215166.2.107.0/25166.2.107.1 to 166.2.107.126166.2.107.127126
216166.2.107.128/25166.2.107.129 to 166.2.107.254166.2.107.255126
217166.2.108.0/25166.2.108.1 to 166.2.108.126166.2.108.127126
218166.2.108.128/25166.2.108.129 to 166.2.108.254166.2.108.255126
219166.2.109.0/25166.2.109.1 to 166.2.109.126166.2.109.127126
220166.2.109.128/25166.2.109.129 to 166.2.109.254166.2.109.255126
221166.2.110.0/25166.2.110.1 to 166.2.110.126166.2.110.127126
222166.2.110.128/25166.2.110.129 to 166.2.110.254166.2.110.255126
223166.2.111.0/25166.2.111.1 to 166.2.111.126166.2.111.127126
224166.2.111.128/25166.2.111.129 to 166.2.111.254166.2.111.255126
225166.2.112.0/25166.2.112.1 to 166.2.112.126166.2.112.127126
226166.2.112.128/25166.2.112.129 to 166.2.112.254166.2.112.255126
227166.2.113.0/25166.2.113.1 to 166.2.113.126166.2.113.127126
228166.2.113.128/25166.2.113.129 to 166.2.113.254166.2.113.255126
229166.2.114.0/25166.2.114.1 to 166.2.114.126166.2.114.127126
230166.2.114.128/25166.2.114.129 to 166.2.114.254166.2.114.255126
231166.2.115.0/25166.2.115.1 to 166.2.115.126166.2.115.127126
232166.2.115.128/25166.2.115.129 to 166.2.115.254166.2.115.255126
233166.2.116.0/25166.2.116.1 to 166.2.116.126166.2.116.127126
234166.2.116.128/25166.2.116.129 to 166.2.116.254166.2.116.255126
235166.2.117.0/25166.2.117.1 to 166.2.117.126166.2.117.127126
236166.2.117.128/25166.2.117.129 to 166.2.117.254166.2.117.255126
237166.2.118.0/25166.2.118.1 to 166.2.118.126166.2.118.127126
238166.2.118.128/25166.2.118.129 to 166.2.118.254166.2.118.255126
239166.2.119.0/25166.2.119.1 to 166.2.119.126166.2.119.127126
240166.2.119.128/25166.2.119.129 to 166.2.119.254166.2.119.255126
241166.2.120.0/25166.2.120.1 to 166.2.120.126166.2.120.127126
242166.2.120.128/25166.2.120.129 to 166.2.120.254166.2.120.255126
243166.2.121.0/25166.2.121.1 to 166.2.121.126166.2.121.127126
244166.2.121.128/25166.2.121.129 to 166.2.121.254166.2.121.255126
245166.2.122.0/25166.2.122.1 to 166.2.122.126166.2.122.127126
246166.2.122.128/25166.2.122.129 to 166.2.122.254166.2.122.255126
247166.2.123.0/25166.2.123.1 to 166.2.123.126166.2.123.127126
248166.2.123.128/25166.2.123.129 to 166.2.123.254166.2.123.255126
249166.2.124.0/25166.2.124.1 to 166.2.124.126166.2.124.127126
250166.2.124.128/25166.2.124.129 to 166.2.124.254166.2.124.255126
251166.2.125.0/25166.2.125.1 to 166.2.125.126166.2.125.127126
252166.2.125.128/25166.2.125.129 to 166.2.125.254166.2.125.255126
253166.2.126.0/25166.2.126.1 to 166.2.126.126166.2.126.127126
254166.2.126.128/25166.2.126.129 to 166.2.126.254166.2.126.255126
255166.2.127.0/25166.2.127.1 to 166.2.127.126166.2.127.127126
256166.2.127.128/25166.2.127.129 to 166.2.127.254166.2.127.255126

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.