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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.

Network181.243.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
181.243.0.0
Broadcast address
181.243.255.255
First usable
181.243.0.1
Last usable
181.243.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
B (default /16)
As numbers
Hex B5F30000 · Integer 3052601344 to 3052666879
Reverse DNS zone
243.181.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110101.11110011..00000000.00000000181.243.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10110101.11110011..00000000.00000000181.243.0.0
Broadcast10110101.11110011..11111111.11111111181.243.255.255
Split into smaller subnets/25
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

181.243.0.0/16 makes 512 subnets of /25; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1181.243.0.0/25181.243.0.1 to 181.243.0.126181.243.0.127126
2181.243.0.128/25181.243.0.129 to 181.243.0.254181.243.0.255126
3181.243.1.0/25181.243.1.1 to 181.243.1.126181.243.1.127126
4181.243.1.128/25181.243.1.129 to 181.243.1.254181.243.1.255126
5181.243.2.0/25181.243.2.1 to 181.243.2.126181.243.2.127126
6181.243.2.128/25181.243.2.129 to 181.243.2.254181.243.2.255126
7181.243.3.0/25181.243.3.1 to 181.243.3.126181.243.3.127126
8181.243.3.128/25181.243.3.129 to 181.243.3.254181.243.3.255126
9181.243.4.0/25181.243.4.1 to 181.243.4.126181.243.4.127126
10181.243.4.128/25181.243.4.129 to 181.243.4.254181.243.4.255126
11181.243.5.0/25181.243.5.1 to 181.243.5.126181.243.5.127126
12181.243.5.128/25181.243.5.129 to 181.243.5.254181.243.5.255126
13181.243.6.0/25181.243.6.1 to 181.243.6.126181.243.6.127126
14181.243.6.128/25181.243.6.129 to 181.243.6.254181.243.6.255126
15181.243.7.0/25181.243.7.1 to 181.243.7.126181.243.7.127126
16181.243.7.128/25181.243.7.129 to 181.243.7.254181.243.7.255126
17181.243.8.0/25181.243.8.1 to 181.243.8.126181.243.8.127126
18181.243.8.128/25181.243.8.129 to 181.243.8.254181.243.8.255126
19181.243.9.0/25181.243.9.1 to 181.243.9.126181.243.9.127126
20181.243.9.128/25181.243.9.129 to 181.243.9.254181.243.9.255126
21181.243.10.0/25181.243.10.1 to 181.243.10.126181.243.10.127126
22181.243.10.128/25181.243.10.129 to 181.243.10.254181.243.10.255126
23181.243.11.0/25181.243.11.1 to 181.243.11.126181.243.11.127126
24181.243.11.128/25181.243.11.129 to 181.243.11.254181.243.11.255126
25181.243.12.0/25181.243.12.1 to 181.243.12.126181.243.12.127126
26181.243.12.128/25181.243.12.129 to 181.243.12.254181.243.12.255126
27181.243.13.0/25181.243.13.1 to 181.243.13.126181.243.13.127126
28181.243.13.128/25181.243.13.129 to 181.243.13.254181.243.13.255126
29181.243.14.0/25181.243.14.1 to 181.243.14.126181.243.14.127126
30181.243.14.128/25181.243.14.129 to 181.243.14.254181.243.14.255126
31181.243.15.0/25181.243.15.1 to 181.243.15.126181.243.15.127126
32181.243.15.128/25181.243.15.129 to 181.243.15.254181.243.15.255126
33181.243.16.0/25181.243.16.1 to 181.243.16.126181.243.16.127126
34181.243.16.128/25181.243.16.129 to 181.243.16.254181.243.16.255126
35181.243.17.0/25181.243.17.1 to 181.243.17.126181.243.17.127126
36181.243.17.128/25181.243.17.129 to 181.243.17.254181.243.17.255126
37181.243.18.0/25181.243.18.1 to 181.243.18.126181.243.18.127126
38181.243.18.128/25181.243.18.129 to 181.243.18.254181.243.18.255126
39181.243.19.0/25181.243.19.1 to 181.243.19.126181.243.19.127126
40181.243.19.128/25181.243.19.129 to 181.243.19.254181.243.19.255126
41181.243.20.0/25181.243.20.1 to 181.243.20.126181.243.20.127126
42181.243.20.128/25181.243.20.129 to 181.243.20.254181.243.20.255126
43181.243.21.0/25181.243.21.1 to 181.243.21.126181.243.21.127126
44181.243.21.128/25181.243.21.129 to 181.243.21.254181.243.21.255126
45181.243.22.0/25181.243.22.1 to 181.243.22.126181.243.22.127126
46181.243.22.128/25181.243.22.129 to 181.243.22.254181.243.22.255126
47181.243.23.0/25181.243.23.1 to 181.243.23.126181.243.23.127126
48181.243.23.128/25181.243.23.129 to 181.243.23.254181.243.23.255126
49181.243.24.0/25181.243.24.1 to 181.243.24.126181.243.24.127126
50181.243.24.128/25181.243.24.129 to 181.243.24.254181.243.24.255126
51181.243.25.0/25181.243.25.1 to 181.243.25.126181.243.25.127126
52181.243.25.128/25181.243.25.129 to 181.243.25.254181.243.25.255126
53181.243.26.0/25181.243.26.1 to 181.243.26.126181.243.26.127126
54181.243.26.128/25181.243.26.129 to 181.243.26.254181.243.26.255126
55181.243.27.0/25181.243.27.1 to 181.243.27.126181.243.27.127126
56181.243.27.128/25181.243.27.129 to 181.243.27.254181.243.27.255126
57181.243.28.0/25181.243.28.1 to 181.243.28.126181.243.28.127126
58181.243.28.128/25181.243.28.129 to 181.243.28.254181.243.28.255126
59181.243.29.0/25181.243.29.1 to 181.243.29.126181.243.29.127126
60181.243.29.128/25181.243.29.129 to 181.243.29.254181.243.29.255126
61181.243.30.0/25181.243.30.1 to 181.243.30.126181.243.30.127126
62181.243.30.128/25181.243.30.129 to 181.243.30.254181.243.30.255126
63181.243.31.0/25181.243.31.1 to 181.243.31.126181.243.31.127126
64181.243.31.128/25181.243.31.129 to 181.243.31.254181.243.31.255126
65181.243.32.0/25181.243.32.1 to 181.243.32.126181.243.32.127126
66181.243.32.128/25181.243.32.129 to 181.243.32.254181.243.32.255126
67181.243.33.0/25181.243.33.1 to 181.243.33.126181.243.33.127126
68181.243.33.128/25181.243.33.129 to 181.243.33.254181.243.33.255126
69181.243.34.0/25181.243.34.1 to 181.243.34.126181.243.34.127126
70181.243.34.128/25181.243.34.129 to 181.243.34.254181.243.34.255126
71181.243.35.0/25181.243.35.1 to 181.243.35.126181.243.35.127126
72181.243.35.128/25181.243.35.129 to 181.243.35.254181.243.35.255126
73181.243.36.0/25181.243.36.1 to 181.243.36.126181.243.36.127126
74181.243.36.128/25181.243.36.129 to 181.243.36.254181.243.36.255126
75181.243.37.0/25181.243.37.1 to 181.243.37.126181.243.37.127126
76181.243.37.128/25181.243.37.129 to 181.243.37.254181.243.37.255126
77181.243.38.0/25181.243.38.1 to 181.243.38.126181.243.38.127126
78181.243.38.128/25181.243.38.129 to 181.243.38.254181.243.38.255126
79181.243.39.0/25181.243.39.1 to 181.243.39.126181.243.39.127126
80181.243.39.128/25181.243.39.129 to 181.243.39.254181.243.39.255126
81181.243.40.0/25181.243.40.1 to 181.243.40.126181.243.40.127126
82181.243.40.128/25181.243.40.129 to 181.243.40.254181.243.40.255126
83181.243.41.0/25181.243.41.1 to 181.243.41.126181.243.41.127126
84181.243.41.128/25181.243.41.129 to 181.243.41.254181.243.41.255126
85181.243.42.0/25181.243.42.1 to 181.243.42.126181.243.42.127126
86181.243.42.128/25181.243.42.129 to 181.243.42.254181.243.42.255126
87181.243.43.0/25181.243.43.1 to 181.243.43.126181.243.43.127126
88181.243.43.128/25181.243.43.129 to 181.243.43.254181.243.43.255126
89181.243.44.0/25181.243.44.1 to 181.243.44.126181.243.44.127126
90181.243.44.128/25181.243.44.129 to 181.243.44.254181.243.44.255126
91181.243.45.0/25181.243.45.1 to 181.243.45.126181.243.45.127126
92181.243.45.128/25181.243.45.129 to 181.243.45.254181.243.45.255126
93181.243.46.0/25181.243.46.1 to 181.243.46.126181.243.46.127126
94181.243.46.128/25181.243.46.129 to 181.243.46.254181.243.46.255126
95181.243.47.0/25181.243.47.1 to 181.243.47.126181.243.47.127126
96181.243.47.128/25181.243.47.129 to 181.243.47.254181.243.47.255126
97181.243.48.0/25181.243.48.1 to 181.243.48.126181.243.48.127126
98181.243.48.128/25181.243.48.129 to 181.243.48.254181.243.48.255126
99181.243.49.0/25181.243.49.1 to 181.243.49.126181.243.49.127126
100181.243.49.128/25181.243.49.129 to 181.243.49.254181.243.49.255126
101181.243.50.0/25181.243.50.1 to 181.243.50.126181.243.50.127126
102181.243.50.128/25181.243.50.129 to 181.243.50.254181.243.50.255126
103181.243.51.0/25181.243.51.1 to 181.243.51.126181.243.51.127126
104181.243.51.128/25181.243.51.129 to 181.243.51.254181.243.51.255126
105181.243.52.0/25181.243.52.1 to 181.243.52.126181.243.52.127126
106181.243.52.128/25181.243.52.129 to 181.243.52.254181.243.52.255126
107181.243.53.0/25181.243.53.1 to 181.243.53.126181.243.53.127126
108181.243.53.128/25181.243.53.129 to 181.243.53.254181.243.53.255126
109181.243.54.0/25181.243.54.1 to 181.243.54.126181.243.54.127126
110181.243.54.128/25181.243.54.129 to 181.243.54.254181.243.54.255126
111181.243.55.0/25181.243.55.1 to 181.243.55.126181.243.55.127126
112181.243.55.128/25181.243.55.129 to 181.243.55.254181.243.55.255126
113181.243.56.0/25181.243.56.1 to 181.243.56.126181.243.56.127126
114181.243.56.128/25181.243.56.129 to 181.243.56.254181.243.56.255126
115181.243.57.0/25181.243.57.1 to 181.243.57.126181.243.57.127126
116181.243.57.128/25181.243.57.129 to 181.243.57.254181.243.57.255126
117181.243.58.0/25181.243.58.1 to 181.243.58.126181.243.58.127126
118181.243.58.128/25181.243.58.129 to 181.243.58.254181.243.58.255126
119181.243.59.0/25181.243.59.1 to 181.243.59.126181.243.59.127126
120181.243.59.128/25181.243.59.129 to 181.243.59.254181.243.59.255126
121181.243.60.0/25181.243.60.1 to 181.243.60.126181.243.60.127126
122181.243.60.128/25181.243.60.129 to 181.243.60.254181.243.60.255126
123181.243.61.0/25181.243.61.1 to 181.243.61.126181.243.61.127126
124181.243.61.128/25181.243.61.129 to 181.243.61.254181.243.61.255126
125181.243.62.0/25181.243.62.1 to 181.243.62.126181.243.62.127126
126181.243.62.128/25181.243.62.129 to 181.243.62.254181.243.62.255126
127181.243.63.0/25181.243.63.1 to 181.243.63.126181.243.63.127126
128181.243.63.128/25181.243.63.129 to 181.243.63.254181.243.63.255126
129181.243.64.0/25181.243.64.1 to 181.243.64.126181.243.64.127126
130181.243.64.128/25181.243.64.129 to 181.243.64.254181.243.64.255126
131181.243.65.0/25181.243.65.1 to 181.243.65.126181.243.65.127126
132181.243.65.128/25181.243.65.129 to 181.243.65.254181.243.65.255126
133181.243.66.0/25181.243.66.1 to 181.243.66.126181.243.66.127126
134181.243.66.128/25181.243.66.129 to 181.243.66.254181.243.66.255126
135181.243.67.0/25181.243.67.1 to 181.243.67.126181.243.67.127126
136181.243.67.128/25181.243.67.129 to 181.243.67.254181.243.67.255126
137181.243.68.0/25181.243.68.1 to 181.243.68.126181.243.68.127126
138181.243.68.128/25181.243.68.129 to 181.243.68.254181.243.68.255126
139181.243.69.0/25181.243.69.1 to 181.243.69.126181.243.69.127126
140181.243.69.128/25181.243.69.129 to 181.243.69.254181.243.69.255126
141181.243.70.0/25181.243.70.1 to 181.243.70.126181.243.70.127126
142181.243.70.128/25181.243.70.129 to 181.243.70.254181.243.70.255126
143181.243.71.0/25181.243.71.1 to 181.243.71.126181.243.71.127126
144181.243.71.128/25181.243.71.129 to 181.243.71.254181.243.71.255126
145181.243.72.0/25181.243.72.1 to 181.243.72.126181.243.72.127126
146181.243.72.128/25181.243.72.129 to 181.243.72.254181.243.72.255126
147181.243.73.0/25181.243.73.1 to 181.243.73.126181.243.73.127126
148181.243.73.128/25181.243.73.129 to 181.243.73.254181.243.73.255126
149181.243.74.0/25181.243.74.1 to 181.243.74.126181.243.74.127126
150181.243.74.128/25181.243.74.129 to 181.243.74.254181.243.74.255126
151181.243.75.0/25181.243.75.1 to 181.243.75.126181.243.75.127126
152181.243.75.128/25181.243.75.129 to 181.243.75.254181.243.75.255126
153181.243.76.0/25181.243.76.1 to 181.243.76.126181.243.76.127126
154181.243.76.128/25181.243.76.129 to 181.243.76.254181.243.76.255126
155181.243.77.0/25181.243.77.1 to 181.243.77.126181.243.77.127126
156181.243.77.128/25181.243.77.129 to 181.243.77.254181.243.77.255126
157181.243.78.0/25181.243.78.1 to 181.243.78.126181.243.78.127126
158181.243.78.128/25181.243.78.129 to 181.243.78.254181.243.78.255126
159181.243.79.0/25181.243.79.1 to 181.243.79.126181.243.79.127126
160181.243.79.128/25181.243.79.129 to 181.243.79.254181.243.79.255126
161181.243.80.0/25181.243.80.1 to 181.243.80.126181.243.80.127126
162181.243.80.128/25181.243.80.129 to 181.243.80.254181.243.80.255126
163181.243.81.0/25181.243.81.1 to 181.243.81.126181.243.81.127126
164181.243.81.128/25181.243.81.129 to 181.243.81.254181.243.81.255126
165181.243.82.0/25181.243.82.1 to 181.243.82.126181.243.82.127126
166181.243.82.128/25181.243.82.129 to 181.243.82.254181.243.82.255126
167181.243.83.0/25181.243.83.1 to 181.243.83.126181.243.83.127126
168181.243.83.128/25181.243.83.129 to 181.243.83.254181.243.83.255126
169181.243.84.0/25181.243.84.1 to 181.243.84.126181.243.84.127126
170181.243.84.128/25181.243.84.129 to 181.243.84.254181.243.84.255126
171181.243.85.0/25181.243.85.1 to 181.243.85.126181.243.85.127126
172181.243.85.128/25181.243.85.129 to 181.243.85.254181.243.85.255126
173181.243.86.0/25181.243.86.1 to 181.243.86.126181.243.86.127126
174181.243.86.128/25181.243.86.129 to 181.243.86.254181.243.86.255126
175181.243.87.0/25181.243.87.1 to 181.243.87.126181.243.87.127126
176181.243.87.128/25181.243.87.129 to 181.243.87.254181.243.87.255126
177181.243.88.0/25181.243.88.1 to 181.243.88.126181.243.88.127126
178181.243.88.128/25181.243.88.129 to 181.243.88.254181.243.88.255126
179181.243.89.0/25181.243.89.1 to 181.243.89.126181.243.89.127126
180181.243.89.128/25181.243.89.129 to 181.243.89.254181.243.89.255126
181181.243.90.0/25181.243.90.1 to 181.243.90.126181.243.90.127126
182181.243.90.128/25181.243.90.129 to 181.243.90.254181.243.90.255126
183181.243.91.0/25181.243.91.1 to 181.243.91.126181.243.91.127126
184181.243.91.128/25181.243.91.129 to 181.243.91.254181.243.91.255126
185181.243.92.0/25181.243.92.1 to 181.243.92.126181.243.92.127126
186181.243.92.128/25181.243.92.129 to 181.243.92.254181.243.92.255126
187181.243.93.0/25181.243.93.1 to 181.243.93.126181.243.93.127126
188181.243.93.128/25181.243.93.129 to 181.243.93.254181.243.93.255126
189181.243.94.0/25181.243.94.1 to 181.243.94.126181.243.94.127126
190181.243.94.128/25181.243.94.129 to 181.243.94.254181.243.94.255126
191181.243.95.0/25181.243.95.1 to 181.243.95.126181.243.95.127126
192181.243.95.128/25181.243.95.129 to 181.243.95.254181.243.95.255126
193181.243.96.0/25181.243.96.1 to 181.243.96.126181.243.96.127126
194181.243.96.128/25181.243.96.129 to 181.243.96.254181.243.96.255126
195181.243.97.0/25181.243.97.1 to 181.243.97.126181.243.97.127126
196181.243.97.128/25181.243.97.129 to 181.243.97.254181.243.97.255126
197181.243.98.0/25181.243.98.1 to 181.243.98.126181.243.98.127126
198181.243.98.128/25181.243.98.129 to 181.243.98.254181.243.98.255126
199181.243.99.0/25181.243.99.1 to 181.243.99.126181.243.99.127126
200181.243.99.128/25181.243.99.129 to 181.243.99.254181.243.99.255126
201181.243.100.0/25181.243.100.1 to 181.243.100.126181.243.100.127126
202181.243.100.128/25181.243.100.129 to 181.243.100.254181.243.100.255126
203181.243.101.0/25181.243.101.1 to 181.243.101.126181.243.101.127126
204181.243.101.128/25181.243.101.129 to 181.243.101.254181.243.101.255126
205181.243.102.0/25181.243.102.1 to 181.243.102.126181.243.102.127126
206181.243.102.128/25181.243.102.129 to 181.243.102.254181.243.102.255126
207181.243.103.0/25181.243.103.1 to 181.243.103.126181.243.103.127126
208181.243.103.128/25181.243.103.129 to 181.243.103.254181.243.103.255126
209181.243.104.0/25181.243.104.1 to 181.243.104.126181.243.104.127126
210181.243.104.128/25181.243.104.129 to 181.243.104.254181.243.104.255126
211181.243.105.0/25181.243.105.1 to 181.243.105.126181.243.105.127126
212181.243.105.128/25181.243.105.129 to 181.243.105.254181.243.105.255126
213181.243.106.0/25181.243.106.1 to 181.243.106.126181.243.106.127126
214181.243.106.128/25181.243.106.129 to 181.243.106.254181.243.106.255126
215181.243.107.0/25181.243.107.1 to 181.243.107.126181.243.107.127126
216181.243.107.128/25181.243.107.129 to 181.243.107.254181.243.107.255126
217181.243.108.0/25181.243.108.1 to 181.243.108.126181.243.108.127126
218181.243.108.128/25181.243.108.129 to 181.243.108.254181.243.108.255126
219181.243.109.0/25181.243.109.1 to 181.243.109.126181.243.109.127126
220181.243.109.128/25181.243.109.129 to 181.243.109.254181.243.109.255126
221181.243.110.0/25181.243.110.1 to 181.243.110.126181.243.110.127126
222181.243.110.128/25181.243.110.129 to 181.243.110.254181.243.110.255126
223181.243.111.0/25181.243.111.1 to 181.243.111.126181.243.111.127126
224181.243.111.128/25181.243.111.129 to 181.243.111.254181.243.111.255126
225181.243.112.0/25181.243.112.1 to 181.243.112.126181.243.112.127126
226181.243.112.128/25181.243.112.129 to 181.243.112.254181.243.112.255126
227181.243.113.0/25181.243.113.1 to 181.243.113.126181.243.113.127126
228181.243.113.128/25181.243.113.129 to 181.243.113.254181.243.113.255126
229181.243.114.0/25181.243.114.1 to 181.243.114.126181.243.114.127126
230181.243.114.128/25181.243.114.129 to 181.243.114.254181.243.114.255126
231181.243.115.0/25181.243.115.1 to 181.243.115.126181.243.115.127126
232181.243.115.128/25181.243.115.129 to 181.243.115.254181.243.115.255126
233181.243.116.0/25181.243.116.1 to 181.243.116.126181.243.116.127126
234181.243.116.128/25181.243.116.129 to 181.243.116.254181.243.116.255126
235181.243.117.0/25181.243.117.1 to 181.243.117.126181.243.117.127126
236181.243.117.128/25181.243.117.129 to 181.243.117.254181.243.117.255126
237181.243.118.0/25181.243.118.1 to 181.243.118.126181.243.118.127126
238181.243.118.128/25181.243.118.129 to 181.243.118.254181.243.118.255126
239181.243.119.0/25181.243.119.1 to 181.243.119.126181.243.119.127126
240181.243.119.128/25181.243.119.129 to 181.243.119.254181.243.119.255126
241181.243.120.0/25181.243.120.1 to 181.243.120.126181.243.120.127126
242181.243.120.128/25181.243.120.129 to 181.243.120.254181.243.120.255126
243181.243.121.0/25181.243.121.1 to 181.243.121.126181.243.121.127126
244181.243.121.128/25181.243.121.129 to 181.243.121.254181.243.121.255126
245181.243.122.0/25181.243.122.1 to 181.243.122.126181.243.122.127126
246181.243.122.128/25181.243.122.129 to 181.243.122.254181.243.122.255126
247181.243.123.0/25181.243.123.1 to 181.243.123.126181.243.123.127126
248181.243.123.128/25181.243.123.129 to 181.243.123.254181.243.123.255126
249181.243.124.0/25181.243.124.1 to 181.243.124.126181.243.124.127126
250181.243.124.128/25181.243.124.129 to 181.243.124.254181.243.124.255126
251181.243.125.0/25181.243.125.1 to 181.243.125.126181.243.125.127126
252181.243.125.128/25181.243.125.129 to 181.243.125.254181.243.125.255126
253181.243.126.0/25181.243.126.1 to 181.243.126.126181.243.126.127126
254181.243.126.128/25181.243.126.129 to 181.243.126.254181.243.126.255126
255181.243.127.0/25181.243.127.1 to 181.243.127.126181.243.127.127126
256181.243.127.128/25181.243.127.129 to 181.243.127.254181.243.127.255126

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.