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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.

Network173.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
173.0.0.0
Broadcast address
173.127.255.255
First usable
173.0.0.1
Last usable
173.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
B (default /16)
As numbers
Hex AD000000 · Integer 2902458368 to 2910846975
Reverse DNS zones
0.173.in-addr.arpa
1.173.in-addr.arpa
2.173.in-addr.arpa
3.173.in-addr.arpa
4.173.in-addr.arpa
5.173.in-addr.arpa
6.173.in-addr.arpa
7.173.in-addr.arpa
8.173.in-addr.arpa
9.173.in-addr.arpa
10.173.in-addr.arpa
11.173.in-addr.arpa
12.173.in-addr.arpa
13.173.in-addr.arpa
14.173.in-addr.arpa
15.173.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101101.00000000.00000000.00000000173.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network10101101.00000000.00000000.00000000173.0.0.0
Broadcast10101101.01111111.11111111.11111111173.127.255.255
Split into smaller subnets/17
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

173.0.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1173.0.0.0/17173.0.0.1 to 173.0.127.254173.0.127.25532,766
2173.0.128.0/17173.0.128.1 to 173.0.255.254173.0.255.25532,766
3173.1.0.0/17173.1.0.1 to 173.1.127.254173.1.127.25532,766
4173.1.128.0/17173.1.128.1 to 173.1.255.254173.1.255.25532,766
5173.2.0.0/17173.2.0.1 to 173.2.127.254173.2.127.25532,766
6173.2.128.0/17173.2.128.1 to 173.2.255.254173.2.255.25532,766
7173.3.0.0/17173.3.0.1 to 173.3.127.254173.3.127.25532,766
8173.3.128.0/17173.3.128.1 to 173.3.255.254173.3.255.25532,766
9173.4.0.0/17173.4.0.1 to 173.4.127.254173.4.127.25532,766
10173.4.128.0/17173.4.128.1 to 173.4.255.254173.4.255.25532,766
11173.5.0.0/17173.5.0.1 to 173.5.127.254173.5.127.25532,766
12173.5.128.0/17173.5.128.1 to 173.5.255.254173.5.255.25532,766
13173.6.0.0/17173.6.0.1 to 173.6.127.254173.6.127.25532,766
14173.6.128.0/17173.6.128.1 to 173.6.255.254173.6.255.25532,766
15173.7.0.0/17173.7.0.1 to 173.7.127.254173.7.127.25532,766
16173.7.128.0/17173.7.128.1 to 173.7.255.254173.7.255.25532,766
17173.8.0.0/17173.8.0.1 to 173.8.127.254173.8.127.25532,766
18173.8.128.0/17173.8.128.1 to 173.8.255.254173.8.255.25532,766
19173.9.0.0/17173.9.0.1 to 173.9.127.254173.9.127.25532,766
20173.9.128.0/17173.9.128.1 to 173.9.255.254173.9.255.25532,766
21173.10.0.0/17173.10.0.1 to 173.10.127.254173.10.127.25532,766
22173.10.128.0/17173.10.128.1 to 173.10.255.254173.10.255.25532,766
23173.11.0.0/17173.11.0.1 to 173.11.127.254173.11.127.25532,766
24173.11.128.0/17173.11.128.1 to 173.11.255.254173.11.255.25532,766
25173.12.0.0/17173.12.0.1 to 173.12.127.254173.12.127.25532,766
26173.12.128.0/17173.12.128.1 to 173.12.255.254173.12.255.25532,766
27173.13.0.0/17173.13.0.1 to 173.13.127.254173.13.127.25532,766
28173.13.128.0/17173.13.128.1 to 173.13.255.254173.13.255.25532,766
29173.14.0.0/17173.14.0.1 to 173.14.127.254173.14.127.25532,766
30173.14.128.0/17173.14.128.1 to 173.14.255.254173.14.255.25532,766
31173.15.0.0/17173.15.0.1 to 173.15.127.254173.15.127.25532,766
32173.15.128.0/17173.15.128.1 to 173.15.255.254173.15.255.25532,766
33173.16.0.0/17173.16.0.1 to 173.16.127.254173.16.127.25532,766
34173.16.128.0/17173.16.128.1 to 173.16.255.254173.16.255.25532,766
35173.17.0.0/17173.17.0.1 to 173.17.127.254173.17.127.25532,766
36173.17.128.0/17173.17.128.1 to 173.17.255.254173.17.255.25532,766
37173.18.0.0/17173.18.0.1 to 173.18.127.254173.18.127.25532,766
38173.18.128.0/17173.18.128.1 to 173.18.255.254173.18.255.25532,766
39173.19.0.0/17173.19.0.1 to 173.19.127.254173.19.127.25532,766
40173.19.128.0/17173.19.128.1 to 173.19.255.254173.19.255.25532,766
41173.20.0.0/17173.20.0.1 to 173.20.127.254173.20.127.25532,766
42173.20.128.0/17173.20.128.1 to 173.20.255.254173.20.255.25532,766
43173.21.0.0/17173.21.0.1 to 173.21.127.254173.21.127.25532,766
44173.21.128.0/17173.21.128.1 to 173.21.255.254173.21.255.25532,766
45173.22.0.0/17173.22.0.1 to 173.22.127.254173.22.127.25532,766
46173.22.128.0/17173.22.128.1 to 173.22.255.254173.22.255.25532,766
47173.23.0.0/17173.23.0.1 to 173.23.127.254173.23.127.25532,766
48173.23.128.0/17173.23.128.1 to 173.23.255.254173.23.255.25532,766
49173.24.0.0/17173.24.0.1 to 173.24.127.254173.24.127.25532,766
50173.24.128.0/17173.24.128.1 to 173.24.255.254173.24.255.25532,766
51173.25.0.0/17173.25.0.1 to 173.25.127.254173.25.127.25532,766
52173.25.128.0/17173.25.128.1 to 173.25.255.254173.25.255.25532,766
53173.26.0.0/17173.26.0.1 to 173.26.127.254173.26.127.25532,766
54173.26.128.0/17173.26.128.1 to 173.26.255.254173.26.255.25532,766
55173.27.0.0/17173.27.0.1 to 173.27.127.254173.27.127.25532,766
56173.27.128.0/17173.27.128.1 to 173.27.255.254173.27.255.25532,766
57173.28.0.0/17173.28.0.1 to 173.28.127.254173.28.127.25532,766
58173.28.128.0/17173.28.128.1 to 173.28.255.254173.28.255.25532,766
59173.29.0.0/17173.29.0.1 to 173.29.127.254173.29.127.25532,766
60173.29.128.0/17173.29.128.1 to 173.29.255.254173.29.255.25532,766
61173.30.0.0/17173.30.0.1 to 173.30.127.254173.30.127.25532,766
62173.30.128.0/17173.30.128.1 to 173.30.255.254173.30.255.25532,766
63173.31.0.0/17173.31.0.1 to 173.31.127.254173.31.127.25532,766
64173.31.128.0/17173.31.128.1 to 173.31.255.254173.31.255.25532,766
65173.32.0.0/17173.32.0.1 to 173.32.127.254173.32.127.25532,766
66173.32.128.0/17173.32.128.1 to 173.32.255.254173.32.255.25532,766
67173.33.0.0/17173.33.0.1 to 173.33.127.254173.33.127.25532,766
68173.33.128.0/17173.33.128.1 to 173.33.255.254173.33.255.25532,766
69173.34.0.0/17173.34.0.1 to 173.34.127.254173.34.127.25532,766
70173.34.128.0/17173.34.128.1 to 173.34.255.254173.34.255.25532,766
71173.35.0.0/17173.35.0.1 to 173.35.127.254173.35.127.25532,766
72173.35.128.0/17173.35.128.1 to 173.35.255.254173.35.255.25532,766
73173.36.0.0/17173.36.0.1 to 173.36.127.254173.36.127.25532,766
74173.36.128.0/17173.36.128.1 to 173.36.255.254173.36.255.25532,766
75173.37.0.0/17173.37.0.1 to 173.37.127.254173.37.127.25532,766
76173.37.128.0/17173.37.128.1 to 173.37.255.254173.37.255.25532,766
77173.38.0.0/17173.38.0.1 to 173.38.127.254173.38.127.25532,766
78173.38.128.0/17173.38.128.1 to 173.38.255.254173.38.255.25532,766
79173.39.0.0/17173.39.0.1 to 173.39.127.254173.39.127.25532,766
80173.39.128.0/17173.39.128.1 to 173.39.255.254173.39.255.25532,766
81173.40.0.0/17173.40.0.1 to 173.40.127.254173.40.127.25532,766
82173.40.128.0/17173.40.128.1 to 173.40.255.254173.40.255.25532,766
83173.41.0.0/17173.41.0.1 to 173.41.127.254173.41.127.25532,766
84173.41.128.0/17173.41.128.1 to 173.41.255.254173.41.255.25532,766
85173.42.0.0/17173.42.0.1 to 173.42.127.254173.42.127.25532,766
86173.42.128.0/17173.42.128.1 to 173.42.255.254173.42.255.25532,766
87173.43.0.0/17173.43.0.1 to 173.43.127.254173.43.127.25532,766
88173.43.128.0/17173.43.128.1 to 173.43.255.254173.43.255.25532,766
89173.44.0.0/17173.44.0.1 to 173.44.127.254173.44.127.25532,766
90173.44.128.0/17173.44.128.1 to 173.44.255.254173.44.255.25532,766
91173.45.0.0/17173.45.0.1 to 173.45.127.254173.45.127.25532,766
92173.45.128.0/17173.45.128.1 to 173.45.255.254173.45.255.25532,766
93173.46.0.0/17173.46.0.1 to 173.46.127.254173.46.127.25532,766
94173.46.128.0/17173.46.128.1 to 173.46.255.254173.46.255.25532,766
95173.47.0.0/17173.47.0.1 to 173.47.127.254173.47.127.25532,766
96173.47.128.0/17173.47.128.1 to 173.47.255.254173.47.255.25532,766
97173.48.0.0/17173.48.0.1 to 173.48.127.254173.48.127.25532,766
98173.48.128.0/17173.48.128.1 to 173.48.255.254173.48.255.25532,766
99173.49.0.0/17173.49.0.1 to 173.49.127.254173.49.127.25532,766
100173.49.128.0/17173.49.128.1 to 173.49.255.254173.49.255.25532,766
101173.50.0.0/17173.50.0.1 to 173.50.127.254173.50.127.25532,766
102173.50.128.0/17173.50.128.1 to 173.50.255.254173.50.255.25532,766
103173.51.0.0/17173.51.0.1 to 173.51.127.254173.51.127.25532,766
104173.51.128.0/17173.51.128.1 to 173.51.255.254173.51.255.25532,766
105173.52.0.0/17173.52.0.1 to 173.52.127.254173.52.127.25532,766
106173.52.128.0/17173.52.128.1 to 173.52.255.254173.52.255.25532,766
107173.53.0.0/17173.53.0.1 to 173.53.127.254173.53.127.25532,766
108173.53.128.0/17173.53.128.1 to 173.53.255.254173.53.255.25532,766
109173.54.0.0/17173.54.0.1 to 173.54.127.254173.54.127.25532,766
110173.54.128.0/17173.54.128.1 to 173.54.255.254173.54.255.25532,766
111173.55.0.0/17173.55.0.1 to 173.55.127.254173.55.127.25532,766
112173.55.128.0/17173.55.128.1 to 173.55.255.254173.55.255.25532,766
113173.56.0.0/17173.56.0.1 to 173.56.127.254173.56.127.25532,766
114173.56.128.0/17173.56.128.1 to 173.56.255.254173.56.255.25532,766
115173.57.0.0/17173.57.0.1 to 173.57.127.254173.57.127.25532,766
116173.57.128.0/17173.57.128.1 to 173.57.255.254173.57.255.25532,766
117173.58.0.0/17173.58.0.1 to 173.58.127.254173.58.127.25532,766
118173.58.128.0/17173.58.128.1 to 173.58.255.254173.58.255.25532,766
119173.59.0.0/17173.59.0.1 to 173.59.127.254173.59.127.25532,766
120173.59.128.0/17173.59.128.1 to 173.59.255.254173.59.255.25532,766
121173.60.0.0/17173.60.0.1 to 173.60.127.254173.60.127.25532,766
122173.60.128.0/17173.60.128.1 to 173.60.255.254173.60.255.25532,766
123173.61.0.0/17173.61.0.1 to 173.61.127.254173.61.127.25532,766
124173.61.128.0/17173.61.128.1 to 173.61.255.254173.61.255.25532,766
125173.62.0.0/17173.62.0.1 to 173.62.127.254173.62.127.25532,766
126173.62.128.0/17173.62.128.1 to 173.62.255.254173.62.255.25532,766
127173.63.0.0/17173.63.0.1 to 173.63.127.254173.63.127.25532,766
128173.63.128.0/17173.63.128.1 to 173.63.255.254173.63.255.25532,766
129173.64.0.0/17173.64.0.1 to 173.64.127.254173.64.127.25532,766
130173.64.128.0/17173.64.128.1 to 173.64.255.254173.64.255.25532,766
131173.65.0.0/17173.65.0.1 to 173.65.127.254173.65.127.25532,766
132173.65.128.0/17173.65.128.1 to 173.65.255.254173.65.255.25532,766
133173.66.0.0/17173.66.0.1 to 173.66.127.254173.66.127.25532,766
134173.66.128.0/17173.66.128.1 to 173.66.255.254173.66.255.25532,766
135173.67.0.0/17173.67.0.1 to 173.67.127.254173.67.127.25532,766
136173.67.128.0/17173.67.128.1 to 173.67.255.254173.67.255.25532,766
137173.68.0.0/17173.68.0.1 to 173.68.127.254173.68.127.25532,766
138173.68.128.0/17173.68.128.1 to 173.68.255.254173.68.255.25532,766
139173.69.0.0/17173.69.0.1 to 173.69.127.254173.69.127.25532,766
140173.69.128.0/17173.69.128.1 to 173.69.255.254173.69.255.25532,766
141173.70.0.0/17173.70.0.1 to 173.70.127.254173.70.127.25532,766
142173.70.128.0/17173.70.128.1 to 173.70.255.254173.70.255.25532,766
143173.71.0.0/17173.71.0.1 to 173.71.127.254173.71.127.25532,766
144173.71.128.0/17173.71.128.1 to 173.71.255.254173.71.255.25532,766
145173.72.0.0/17173.72.0.1 to 173.72.127.254173.72.127.25532,766
146173.72.128.0/17173.72.128.1 to 173.72.255.254173.72.255.25532,766
147173.73.0.0/17173.73.0.1 to 173.73.127.254173.73.127.25532,766
148173.73.128.0/17173.73.128.1 to 173.73.255.254173.73.255.25532,766
149173.74.0.0/17173.74.0.1 to 173.74.127.254173.74.127.25532,766
150173.74.128.0/17173.74.128.1 to 173.74.255.254173.74.255.25532,766
151173.75.0.0/17173.75.0.1 to 173.75.127.254173.75.127.25532,766
152173.75.128.0/17173.75.128.1 to 173.75.255.254173.75.255.25532,766
153173.76.0.0/17173.76.0.1 to 173.76.127.254173.76.127.25532,766
154173.76.128.0/17173.76.128.1 to 173.76.255.254173.76.255.25532,766
155173.77.0.0/17173.77.0.1 to 173.77.127.254173.77.127.25532,766
156173.77.128.0/17173.77.128.1 to 173.77.255.254173.77.255.25532,766
157173.78.0.0/17173.78.0.1 to 173.78.127.254173.78.127.25532,766
158173.78.128.0/17173.78.128.1 to 173.78.255.254173.78.255.25532,766
159173.79.0.0/17173.79.0.1 to 173.79.127.254173.79.127.25532,766
160173.79.128.0/17173.79.128.1 to 173.79.255.254173.79.255.25532,766
161173.80.0.0/17173.80.0.1 to 173.80.127.254173.80.127.25532,766
162173.80.128.0/17173.80.128.1 to 173.80.255.254173.80.255.25532,766
163173.81.0.0/17173.81.0.1 to 173.81.127.254173.81.127.25532,766
164173.81.128.0/17173.81.128.1 to 173.81.255.254173.81.255.25532,766
165173.82.0.0/17173.82.0.1 to 173.82.127.254173.82.127.25532,766
166173.82.128.0/17173.82.128.1 to 173.82.255.254173.82.255.25532,766
167173.83.0.0/17173.83.0.1 to 173.83.127.254173.83.127.25532,766
168173.83.128.0/17173.83.128.1 to 173.83.255.254173.83.255.25532,766
169173.84.0.0/17173.84.0.1 to 173.84.127.254173.84.127.25532,766
170173.84.128.0/17173.84.128.1 to 173.84.255.254173.84.255.25532,766
171173.85.0.0/17173.85.0.1 to 173.85.127.254173.85.127.25532,766
172173.85.128.0/17173.85.128.1 to 173.85.255.254173.85.255.25532,766
173173.86.0.0/17173.86.0.1 to 173.86.127.254173.86.127.25532,766
174173.86.128.0/17173.86.128.1 to 173.86.255.254173.86.255.25532,766
175173.87.0.0/17173.87.0.1 to 173.87.127.254173.87.127.25532,766
176173.87.128.0/17173.87.128.1 to 173.87.255.254173.87.255.25532,766
177173.88.0.0/17173.88.0.1 to 173.88.127.254173.88.127.25532,766
178173.88.128.0/17173.88.128.1 to 173.88.255.254173.88.255.25532,766
179173.89.0.0/17173.89.0.1 to 173.89.127.254173.89.127.25532,766
180173.89.128.0/17173.89.128.1 to 173.89.255.254173.89.255.25532,766
181173.90.0.0/17173.90.0.1 to 173.90.127.254173.90.127.25532,766
182173.90.128.0/17173.90.128.1 to 173.90.255.254173.90.255.25532,766
183173.91.0.0/17173.91.0.1 to 173.91.127.254173.91.127.25532,766
184173.91.128.0/17173.91.128.1 to 173.91.255.254173.91.255.25532,766
185173.92.0.0/17173.92.0.1 to 173.92.127.254173.92.127.25532,766
186173.92.128.0/17173.92.128.1 to 173.92.255.254173.92.255.25532,766
187173.93.0.0/17173.93.0.1 to 173.93.127.254173.93.127.25532,766
188173.93.128.0/17173.93.128.1 to 173.93.255.254173.93.255.25532,766
189173.94.0.0/17173.94.0.1 to 173.94.127.254173.94.127.25532,766
190173.94.128.0/17173.94.128.1 to 173.94.255.254173.94.255.25532,766
191173.95.0.0/17173.95.0.1 to 173.95.127.254173.95.127.25532,766
192173.95.128.0/17173.95.128.1 to 173.95.255.254173.95.255.25532,766
193173.96.0.0/17173.96.0.1 to 173.96.127.254173.96.127.25532,766
194173.96.128.0/17173.96.128.1 to 173.96.255.254173.96.255.25532,766
195173.97.0.0/17173.97.0.1 to 173.97.127.254173.97.127.25532,766
196173.97.128.0/17173.97.128.1 to 173.97.255.254173.97.255.25532,766
197173.98.0.0/17173.98.0.1 to 173.98.127.254173.98.127.25532,766
198173.98.128.0/17173.98.128.1 to 173.98.255.254173.98.255.25532,766
199173.99.0.0/17173.99.0.1 to 173.99.127.254173.99.127.25532,766
200173.99.128.0/17173.99.128.1 to 173.99.255.254173.99.255.25532,766
201173.100.0.0/17173.100.0.1 to 173.100.127.254173.100.127.25532,766
202173.100.128.0/17173.100.128.1 to 173.100.255.254173.100.255.25532,766
203173.101.0.0/17173.101.0.1 to 173.101.127.254173.101.127.25532,766
204173.101.128.0/17173.101.128.1 to 173.101.255.254173.101.255.25532,766
205173.102.0.0/17173.102.0.1 to 173.102.127.254173.102.127.25532,766
206173.102.128.0/17173.102.128.1 to 173.102.255.254173.102.255.25532,766
207173.103.0.0/17173.103.0.1 to 173.103.127.254173.103.127.25532,766
208173.103.128.0/17173.103.128.1 to 173.103.255.254173.103.255.25532,766
209173.104.0.0/17173.104.0.1 to 173.104.127.254173.104.127.25532,766
210173.104.128.0/17173.104.128.1 to 173.104.255.254173.104.255.25532,766
211173.105.0.0/17173.105.0.1 to 173.105.127.254173.105.127.25532,766
212173.105.128.0/17173.105.128.1 to 173.105.255.254173.105.255.25532,766
213173.106.0.0/17173.106.0.1 to 173.106.127.254173.106.127.25532,766
214173.106.128.0/17173.106.128.1 to 173.106.255.254173.106.255.25532,766
215173.107.0.0/17173.107.0.1 to 173.107.127.254173.107.127.25532,766
216173.107.128.0/17173.107.128.1 to 173.107.255.254173.107.255.25532,766
217173.108.0.0/17173.108.0.1 to 173.108.127.254173.108.127.25532,766
218173.108.128.0/17173.108.128.1 to 173.108.255.254173.108.255.25532,766
219173.109.0.0/17173.109.0.1 to 173.109.127.254173.109.127.25532,766
220173.109.128.0/17173.109.128.1 to 173.109.255.254173.109.255.25532,766
221173.110.0.0/17173.110.0.1 to 173.110.127.254173.110.127.25532,766
222173.110.128.0/17173.110.128.1 to 173.110.255.254173.110.255.25532,766
223173.111.0.0/17173.111.0.1 to 173.111.127.254173.111.127.25532,766
224173.111.128.0/17173.111.128.1 to 173.111.255.254173.111.255.25532,766
225173.112.0.0/17173.112.0.1 to 173.112.127.254173.112.127.25532,766
226173.112.128.0/17173.112.128.1 to 173.112.255.254173.112.255.25532,766
227173.113.0.0/17173.113.0.1 to 173.113.127.254173.113.127.25532,766
228173.113.128.0/17173.113.128.1 to 173.113.255.254173.113.255.25532,766
229173.114.0.0/17173.114.0.1 to 173.114.127.254173.114.127.25532,766
230173.114.128.0/17173.114.128.1 to 173.114.255.254173.114.255.25532,766
231173.115.0.0/17173.115.0.1 to 173.115.127.254173.115.127.25532,766
232173.115.128.0/17173.115.128.1 to 173.115.255.254173.115.255.25532,766
233173.116.0.0/17173.116.0.1 to 173.116.127.254173.116.127.25532,766
234173.116.128.0/17173.116.128.1 to 173.116.255.254173.116.255.25532,766
235173.117.0.0/17173.117.0.1 to 173.117.127.254173.117.127.25532,766
236173.117.128.0/17173.117.128.1 to 173.117.255.254173.117.255.25532,766
237173.118.0.0/17173.118.0.1 to 173.118.127.254173.118.127.25532,766
238173.118.128.0/17173.118.128.1 to 173.118.255.254173.118.255.25532,766
239173.119.0.0/17173.119.0.1 to 173.119.127.254173.119.127.25532,766
240173.119.128.0/17173.119.128.1 to 173.119.255.254173.119.255.25532,766
241173.120.0.0/17173.120.0.1 to 173.120.127.254173.120.127.25532,766
242173.120.128.0/17173.120.128.1 to 173.120.255.254173.120.255.25532,766
243173.121.0.0/17173.121.0.1 to 173.121.127.254173.121.127.25532,766
244173.121.128.0/17173.121.128.1 to 173.121.255.254173.121.255.25532,766
245173.122.0.0/17173.122.0.1 to 173.122.127.254173.122.127.25532,766
246173.122.128.0/17173.122.128.1 to 173.122.255.254173.122.255.25532,766
247173.123.0.0/17173.123.0.1 to 173.123.127.254173.123.127.25532,766
248173.123.128.0/17173.123.128.1 to 173.123.255.254173.123.255.25532,766
249173.124.0.0/17173.124.0.1 to 173.124.127.254173.124.127.25532,766
250173.124.128.0/17173.124.128.1 to 173.124.255.254173.124.255.25532,766
251173.125.0.0/17173.125.0.1 to 173.125.127.254173.125.127.25532,766
252173.125.128.0/17173.125.128.1 to 173.125.255.254173.125.255.25532,766
253173.126.0.0/17173.126.0.1 to 173.126.127.254173.126.127.25532,766
254173.126.128.0/17173.126.128.1 to 173.126.255.254173.126.255.25532,766
255173.127.0.0/17173.127.0.1 to 173.127.127.254173.127.127.25532,766
256173.127.128.0/17173.127.128.1 to 173.127.255.254173.127.255.25532,766

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.