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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.

Network237.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
237.0.0.0
Broadcast address
237.255.255.255
First usable
237.0.0.1
Last usable
237.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex ED000000 · Integer 3976200192 to 3992977407
Reverse DNS zone
237.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101101..00000000.00000000.00000000237.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11101101..00000000.00000000.00000000237.0.0.0
Broadcast11101101..11111111.11111111.11111111237.255.255.255
Split into smaller subnets/17
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

237.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1237.0.0.0/17237.0.0.1 to 237.0.127.254237.0.127.25532,766
2237.0.128.0/17237.0.128.1 to 237.0.255.254237.0.255.25532,766
3237.1.0.0/17237.1.0.1 to 237.1.127.254237.1.127.25532,766
4237.1.128.0/17237.1.128.1 to 237.1.255.254237.1.255.25532,766
5237.2.0.0/17237.2.0.1 to 237.2.127.254237.2.127.25532,766
6237.2.128.0/17237.2.128.1 to 237.2.255.254237.2.255.25532,766
7237.3.0.0/17237.3.0.1 to 237.3.127.254237.3.127.25532,766
8237.3.128.0/17237.3.128.1 to 237.3.255.254237.3.255.25532,766
9237.4.0.0/17237.4.0.1 to 237.4.127.254237.4.127.25532,766
10237.4.128.0/17237.4.128.1 to 237.4.255.254237.4.255.25532,766
11237.5.0.0/17237.5.0.1 to 237.5.127.254237.5.127.25532,766
12237.5.128.0/17237.5.128.1 to 237.5.255.254237.5.255.25532,766
13237.6.0.0/17237.6.0.1 to 237.6.127.254237.6.127.25532,766
14237.6.128.0/17237.6.128.1 to 237.6.255.254237.6.255.25532,766
15237.7.0.0/17237.7.0.1 to 237.7.127.254237.7.127.25532,766
16237.7.128.0/17237.7.128.1 to 237.7.255.254237.7.255.25532,766
17237.8.0.0/17237.8.0.1 to 237.8.127.254237.8.127.25532,766
18237.8.128.0/17237.8.128.1 to 237.8.255.254237.8.255.25532,766
19237.9.0.0/17237.9.0.1 to 237.9.127.254237.9.127.25532,766
20237.9.128.0/17237.9.128.1 to 237.9.255.254237.9.255.25532,766
21237.10.0.0/17237.10.0.1 to 237.10.127.254237.10.127.25532,766
22237.10.128.0/17237.10.128.1 to 237.10.255.254237.10.255.25532,766
23237.11.0.0/17237.11.0.1 to 237.11.127.254237.11.127.25532,766
24237.11.128.0/17237.11.128.1 to 237.11.255.254237.11.255.25532,766
25237.12.0.0/17237.12.0.1 to 237.12.127.254237.12.127.25532,766
26237.12.128.0/17237.12.128.1 to 237.12.255.254237.12.255.25532,766
27237.13.0.0/17237.13.0.1 to 237.13.127.254237.13.127.25532,766
28237.13.128.0/17237.13.128.1 to 237.13.255.254237.13.255.25532,766
29237.14.0.0/17237.14.0.1 to 237.14.127.254237.14.127.25532,766
30237.14.128.0/17237.14.128.1 to 237.14.255.254237.14.255.25532,766
31237.15.0.0/17237.15.0.1 to 237.15.127.254237.15.127.25532,766
32237.15.128.0/17237.15.128.1 to 237.15.255.254237.15.255.25532,766
33237.16.0.0/17237.16.0.1 to 237.16.127.254237.16.127.25532,766
34237.16.128.0/17237.16.128.1 to 237.16.255.254237.16.255.25532,766
35237.17.0.0/17237.17.0.1 to 237.17.127.254237.17.127.25532,766
36237.17.128.0/17237.17.128.1 to 237.17.255.254237.17.255.25532,766
37237.18.0.0/17237.18.0.1 to 237.18.127.254237.18.127.25532,766
38237.18.128.0/17237.18.128.1 to 237.18.255.254237.18.255.25532,766
39237.19.0.0/17237.19.0.1 to 237.19.127.254237.19.127.25532,766
40237.19.128.0/17237.19.128.1 to 237.19.255.254237.19.255.25532,766
41237.20.0.0/17237.20.0.1 to 237.20.127.254237.20.127.25532,766
42237.20.128.0/17237.20.128.1 to 237.20.255.254237.20.255.25532,766
43237.21.0.0/17237.21.0.1 to 237.21.127.254237.21.127.25532,766
44237.21.128.0/17237.21.128.1 to 237.21.255.254237.21.255.25532,766
45237.22.0.0/17237.22.0.1 to 237.22.127.254237.22.127.25532,766
46237.22.128.0/17237.22.128.1 to 237.22.255.254237.22.255.25532,766
47237.23.0.0/17237.23.0.1 to 237.23.127.254237.23.127.25532,766
48237.23.128.0/17237.23.128.1 to 237.23.255.254237.23.255.25532,766
49237.24.0.0/17237.24.0.1 to 237.24.127.254237.24.127.25532,766
50237.24.128.0/17237.24.128.1 to 237.24.255.254237.24.255.25532,766
51237.25.0.0/17237.25.0.1 to 237.25.127.254237.25.127.25532,766
52237.25.128.0/17237.25.128.1 to 237.25.255.254237.25.255.25532,766
53237.26.0.0/17237.26.0.1 to 237.26.127.254237.26.127.25532,766
54237.26.128.0/17237.26.128.1 to 237.26.255.254237.26.255.25532,766
55237.27.0.0/17237.27.0.1 to 237.27.127.254237.27.127.25532,766
56237.27.128.0/17237.27.128.1 to 237.27.255.254237.27.255.25532,766
57237.28.0.0/17237.28.0.1 to 237.28.127.254237.28.127.25532,766
58237.28.128.0/17237.28.128.1 to 237.28.255.254237.28.255.25532,766
59237.29.0.0/17237.29.0.1 to 237.29.127.254237.29.127.25532,766
60237.29.128.0/17237.29.128.1 to 237.29.255.254237.29.255.25532,766
61237.30.0.0/17237.30.0.1 to 237.30.127.254237.30.127.25532,766
62237.30.128.0/17237.30.128.1 to 237.30.255.254237.30.255.25532,766
63237.31.0.0/17237.31.0.1 to 237.31.127.254237.31.127.25532,766
64237.31.128.0/17237.31.128.1 to 237.31.255.254237.31.255.25532,766
65237.32.0.0/17237.32.0.1 to 237.32.127.254237.32.127.25532,766
66237.32.128.0/17237.32.128.1 to 237.32.255.254237.32.255.25532,766
67237.33.0.0/17237.33.0.1 to 237.33.127.254237.33.127.25532,766
68237.33.128.0/17237.33.128.1 to 237.33.255.254237.33.255.25532,766
69237.34.0.0/17237.34.0.1 to 237.34.127.254237.34.127.25532,766
70237.34.128.0/17237.34.128.1 to 237.34.255.254237.34.255.25532,766
71237.35.0.0/17237.35.0.1 to 237.35.127.254237.35.127.25532,766
72237.35.128.0/17237.35.128.1 to 237.35.255.254237.35.255.25532,766
73237.36.0.0/17237.36.0.1 to 237.36.127.254237.36.127.25532,766
74237.36.128.0/17237.36.128.1 to 237.36.255.254237.36.255.25532,766
75237.37.0.0/17237.37.0.1 to 237.37.127.254237.37.127.25532,766
76237.37.128.0/17237.37.128.1 to 237.37.255.254237.37.255.25532,766
77237.38.0.0/17237.38.0.1 to 237.38.127.254237.38.127.25532,766
78237.38.128.0/17237.38.128.1 to 237.38.255.254237.38.255.25532,766
79237.39.0.0/17237.39.0.1 to 237.39.127.254237.39.127.25532,766
80237.39.128.0/17237.39.128.1 to 237.39.255.254237.39.255.25532,766
81237.40.0.0/17237.40.0.1 to 237.40.127.254237.40.127.25532,766
82237.40.128.0/17237.40.128.1 to 237.40.255.254237.40.255.25532,766
83237.41.0.0/17237.41.0.1 to 237.41.127.254237.41.127.25532,766
84237.41.128.0/17237.41.128.1 to 237.41.255.254237.41.255.25532,766
85237.42.0.0/17237.42.0.1 to 237.42.127.254237.42.127.25532,766
86237.42.128.0/17237.42.128.1 to 237.42.255.254237.42.255.25532,766
87237.43.0.0/17237.43.0.1 to 237.43.127.254237.43.127.25532,766
88237.43.128.0/17237.43.128.1 to 237.43.255.254237.43.255.25532,766
89237.44.0.0/17237.44.0.1 to 237.44.127.254237.44.127.25532,766
90237.44.128.0/17237.44.128.1 to 237.44.255.254237.44.255.25532,766
91237.45.0.0/17237.45.0.1 to 237.45.127.254237.45.127.25532,766
92237.45.128.0/17237.45.128.1 to 237.45.255.254237.45.255.25532,766
93237.46.0.0/17237.46.0.1 to 237.46.127.254237.46.127.25532,766
94237.46.128.0/17237.46.128.1 to 237.46.255.254237.46.255.25532,766
95237.47.0.0/17237.47.0.1 to 237.47.127.254237.47.127.25532,766
96237.47.128.0/17237.47.128.1 to 237.47.255.254237.47.255.25532,766
97237.48.0.0/17237.48.0.1 to 237.48.127.254237.48.127.25532,766
98237.48.128.0/17237.48.128.1 to 237.48.255.254237.48.255.25532,766
99237.49.0.0/17237.49.0.1 to 237.49.127.254237.49.127.25532,766
100237.49.128.0/17237.49.128.1 to 237.49.255.254237.49.255.25532,766
101237.50.0.0/17237.50.0.1 to 237.50.127.254237.50.127.25532,766
102237.50.128.0/17237.50.128.1 to 237.50.255.254237.50.255.25532,766
103237.51.0.0/17237.51.0.1 to 237.51.127.254237.51.127.25532,766
104237.51.128.0/17237.51.128.1 to 237.51.255.254237.51.255.25532,766
105237.52.0.0/17237.52.0.1 to 237.52.127.254237.52.127.25532,766
106237.52.128.0/17237.52.128.1 to 237.52.255.254237.52.255.25532,766
107237.53.0.0/17237.53.0.1 to 237.53.127.254237.53.127.25532,766
108237.53.128.0/17237.53.128.1 to 237.53.255.254237.53.255.25532,766
109237.54.0.0/17237.54.0.1 to 237.54.127.254237.54.127.25532,766
110237.54.128.0/17237.54.128.1 to 237.54.255.254237.54.255.25532,766
111237.55.0.0/17237.55.0.1 to 237.55.127.254237.55.127.25532,766
112237.55.128.0/17237.55.128.1 to 237.55.255.254237.55.255.25532,766
113237.56.0.0/17237.56.0.1 to 237.56.127.254237.56.127.25532,766
114237.56.128.0/17237.56.128.1 to 237.56.255.254237.56.255.25532,766
115237.57.0.0/17237.57.0.1 to 237.57.127.254237.57.127.25532,766
116237.57.128.0/17237.57.128.1 to 237.57.255.254237.57.255.25532,766
117237.58.0.0/17237.58.0.1 to 237.58.127.254237.58.127.25532,766
118237.58.128.0/17237.58.128.1 to 237.58.255.254237.58.255.25532,766
119237.59.0.0/17237.59.0.1 to 237.59.127.254237.59.127.25532,766
120237.59.128.0/17237.59.128.1 to 237.59.255.254237.59.255.25532,766
121237.60.0.0/17237.60.0.1 to 237.60.127.254237.60.127.25532,766
122237.60.128.0/17237.60.128.1 to 237.60.255.254237.60.255.25532,766
123237.61.0.0/17237.61.0.1 to 237.61.127.254237.61.127.25532,766
124237.61.128.0/17237.61.128.1 to 237.61.255.254237.61.255.25532,766
125237.62.0.0/17237.62.0.1 to 237.62.127.254237.62.127.25532,766
126237.62.128.0/17237.62.128.1 to 237.62.255.254237.62.255.25532,766
127237.63.0.0/17237.63.0.1 to 237.63.127.254237.63.127.25532,766
128237.63.128.0/17237.63.128.1 to 237.63.255.254237.63.255.25532,766
129237.64.0.0/17237.64.0.1 to 237.64.127.254237.64.127.25532,766
130237.64.128.0/17237.64.128.1 to 237.64.255.254237.64.255.25532,766
131237.65.0.0/17237.65.0.1 to 237.65.127.254237.65.127.25532,766
132237.65.128.0/17237.65.128.1 to 237.65.255.254237.65.255.25532,766
133237.66.0.0/17237.66.0.1 to 237.66.127.254237.66.127.25532,766
134237.66.128.0/17237.66.128.1 to 237.66.255.254237.66.255.25532,766
135237.67.0.0/17237.67.0.1 to 237.67.127.254237.67.127.25532,766
136237.67.128.0/17237.67.128.1 to 237.67.255.254237.67.255.25532,766
137237.68.0.0/17237.68.0.1 to 237.68.127.254237.68.127.25532,766
138237.68.128.0/17237.68.128.1 to 237.68.255.254237.68.255.25532,766
139237.69.0.0/17237.69.0.1 to 237.69.127.254237.69.127.25532,766
140237.69.128.0/17237.69.128.1 to 237.69.255.254237.69.255.25532,766
141237.70.0.0/17237.70.0.1 to 237.70.127.254237.70.127.25532,766
142237.70.128.0/17237.70.128.1 to 237.70.255.254237.70.255.25532,766
143237.71.0.0/17237.71.0.1 to 237.71.127.254237.71.127.25532,766
144237.71.128.0/17237.71.128.1 to 237.71.255.254237.71.255.25532,766
145237.72.0.0/17237.72.0.1 to 237.72.127.254237.72.127.25532,766
146237.72.128.0/17237.72.128.1 to 237.72.255.254237.72.255.25532,766
147237.73.0.0/17237.73.0.1 to 237.73.127.254237.73.127.25532,766
148237.73.128.0/17237.73.128.1 to 237.73.255.254237.73.255.25532,766
149237.74.0.0/17237.74.0.1 to 237.74.127.254237.74.127.25532,766
150237.74.128.0/17237.74.128.1 to 237.74.255.254237.74.255.25532,766
151237.75.0.0/17237.75.0.1 to 237.75.127.254237.75.127.25532,766
152237.75.128.0/17237.75.128.1 to 237.75.255.254237.75.255.25532,766
153237.76.0.0/17237.76.0.1 to 237.76.127.254237.76.127.25532,766
154237.76.128.0/17237.76.128.1 to 237.76.255.254237.76.255.25532,766
155237.77.0.0/17237.77.0.1 to 237.77.127.254237.77.127.25532,766
156237.77.128.0/17237.77.128.1 to 237.77.255.254237.77.255.25532,766
157237.78.0.0/17237.78.0.1 to 237.78.127.254237.78.127.25532,766
158237.78.128.0/17237.78.128.1 to 237.78.255.254237.78.255.25532,766
159237.79.0.0/17237.79.0.1 to 237.79.127.254237.79.127.25532,766
160237.79.128.0/17237.79.128.1 to 237.79.255.254237.79.255.25532,766
161237.80.0.0/17237.80.0.1 to 237.80.127.254237.80.127.25532,766
162237.80.128.0/17237.80.128.1 to 237.80.255.254237.80.255.25532,766
163237.81.0.0/17237.81.0.1 to 237.81.127.254237.81.127.25532,766
164237.81.128.0/17237.81.128.1 to 237.81.255.254237.81.255.25532,766
165237.82.0.0/17237.82.0.1 to 237.82.127.254237.82.127.25532,766
166237.82.128.0/17237.82.128.1 to 237.82.255.254237.82.255.25532,766
167237.83.0.0/17237.83.0.1 to 237.83.127.254237.83.127.25532,766
168237.83.128.0/17237.83.128.1 to 237.83.255.254237.83.255.25532,766
169237.84.0.0/17237.84.0.1 to 237.84.127.254237.84.127.25532,766
170237.84.128.0/17237.84.128.1 to 237.84.255.254237.84.255.25532,766
171237.85.0.0/17237.85.0.1 to 237.85.127.254237.85.127.25532,766
172237.85.128.0/17237.85.128.1 to 237.85.255.254237.85.255.25532,766
173237.86.0.0/17237.86.0.1 to 237.86.127.254237.86.127.25532,766
174237.86.128.0/17237.86.128.1 to 237.86.255.254237.86.255.25532,766
175237.87.0.0/17237.87.0.1 to 237.87.127.254237.87.127.25532,766
176237.87.128.0/17237.87.128.1 to 237.87.255.254237.87.255.25532,766
177237.88.0.0/17237.88.0.1 to 237.88.127.254237.88.127.25532,766
178237.88.128.0/17237.88.128.1 to 237.88.255.254237.88.255.25532,766
179237.89.0.0/17237.89.0.1 to 237.89.127.254237.89.127.25532,766
180237.89.128.0/17237.89.128.1 to 237.89.255.254237.89.255.25532,766
181237.90.0.0/17237.90.0.1 to 237.90.127.254237.90.127.25532,766
182237.90.128.0/17237.90.128.1 to 237.90.255.254237.90.255.25532,766
183237.91.0.0/17237.91.0.1 to 237.91.127.254237.91.127.25532,766
184237.91.128.0/17237.91.128.1 to 237.91.255.254237.91.255.25532,766
185237.92.0.0/17237.92.0.1 to 237.92.127.254237.92.127.25532,766
186237.92.128.0/17237.92.128.1 to 237.92.255.254237.92.255.25532,766
187237.93.0.0/17237.93.0.1 to 237.93.127.254237.93.127.25532,766
188237.93.128.0/17237.93.128.1 to 237.93.255.254237.93.255.25532,766
189237.94.0.0/17237.94.0.1 to 237.94.127.254237.94.127.25532,766
190237.94.128.0/17237.94.128.1 to 237.94.255.254237.94.255.25532,766
191237.95.0.0/17237.95.0.1 to 237.95.127.254237.95.127.25532,766
192237.95.128.0/17237.95.128.1 to 237.95.255.254237.95.255.25532,766
193237.96.0.0/17237.96.0.1 to 237.96.127.254237.96.127.25532,766
194237.96.128.0/17237.96.128.1 to 237.96.255.254237.96.255.25532,766
195237.97.0.0/17237.97.0.1 to 237.97.127.254237.97.127.25532,766
196237.97.128.0/17237.97.128.1 to 237.97.255.254237.97.255.25532,766
197237.98.0.0/17237.98.0.1 to 237.98.127.254237.98.127.25532,766
198237.98.128.0/17237.98.128.1 to 237.98.255.254237.98.255.25532,766
199237.99.0.0/17237.99.0.1 to 237.99.127.254237.99.127.25532,766
200237.99.128.0/17237.99.128.1 to 237.99.255.254237.99.255.25532,766
201237.100.0.0/17237.100.0.1 to 237.100.127.254237.100.127.25532,766
202237.100.128.0/17237.100.128.1 to 237.100.255.254237.100.255.25532,766
203237.101.0.0/17237.101.0.1 to 237.101.127.254237.101.127.25532,766
204237.101.128.0/17237.101.128.1 to 237.101.255.254237.101.255.25532,766
205237.102.0.0/17237.102.0.1 to 237.102.127.254237.102.127.25532,766
206237.102.128.0/17237.102.128.1 to 237.102.255.254237.102.255.25532,766
207237.103.0.0/17237.103.0.1 to 237.103.127.254237.103.127.25532,766
208237.103.128.0/17237.103.128.1 to 237.103.255.254237.103.255.25532,766
209237.104.0.0/17237.104.0.1 to 237.104.127.254237.104.127.25532,766
210237.104.128.0/17237.104.128.1 to 237.104.255.254237.104.255.25532,766
211237.105.0.0/17237.105.0.1 to 237.105.127.254237.105.127.25532,766
212237.105.128.0/17237.105.128.1 to 237.105.255.254237.105.255.25532,766
213237.106.0.0/17237.106.0.1 to 237.106.127.254237.106.127.25532,766
214237.106.128.0/17237.106.128.1 to 237.106.255.254237.106.255.25532,766
215237.107.0.0/17237.107.0.1 to 237.107.127.254237.107.127.25532,766
216237.107.128.0/17237.107.128.1 to 237.107.255.254237.107.255.25532,766
217237.108.0.0/17237.108.0.1 to 237.108.127.254237.108.127.25532,766
218237.108.128.0/17237.108.128.1 to 237.108.255.254237.108.255.25532,766
219237.109.0.0/17237.109.0.1 to 237.109.127.254237.109.127.25532,766
220237.109.128.0/17237.109.128.1 to 237.109.255.254237.109.255.25532,766
221237.110.0.0/17237.110.0.1 to 237.110.127.254237.110.127.25532,766
222237.110.128.0/17237.110.128.1 to 237.110.255.254237.110.255.25532,766
223237.111.0.0/17237.111.0.1 to 237.111.127.254237.111.127.25532,766
224237.111.128.0/17237.111.128.1 to 237.111.255.254237.111.255.25532,766
225237.112.0.0/17237.112.0.1 to 237.112.127.254237.112.127.25532,766
226237.112.128.0/17237.112.128.1 to 237.112.255.254237.112.255.25532,766
227237.113.0.0/17237.113.0.1 to 237.113.127.254237.113.127.25532,766
228237.113.128.0/17237.113.128.1 to 237.113.255.254237.113.255.25532,766
229237.114.0.0/17237.114.0.1 to 237.114.127.254237.114.127.25532,766
230237.114.128.0/17237.114.128.1 to 237.114.255.254237.114.255.25532,766
231237.115.0.0/17237.115.0.1 to 237.115.127.254237.115.127.25532,766
232237.115.128.0/17237.115.128.1 to 237.115.255.254237.115.255.25532,766
233237.116.0.0/17237.116.0.1 to 237.116.127.254237.116.127.25532,766
234237.116.128.0/17237.116.128.1 to 237.116.255.254237.116.255.25532,766
235237.117.0.0/17237.117.0.1 to 237.117.127.254237.117.127.25532,766
236237.117.128.0/17237.117.128.1 to 237.117.255.254237.117.255.25532,766
237237.118.0.0/17237.118.0.1 to 237.118.127.254237.118.127.25532,766
238237.118.128.0/17237.118.128.1 to 237.118.255.254237.118.255.25532,766
239237.119.0.0/17237.119.0.1 to 237.119.127.254237.119.127.25532,766
240237.119.128.0/17237.119.128.1 to 237.119.255.254237.119.255.25532,766
241237.120.0.0/17237.120.0.1 to 237.120.127.254237.120.127.25532,766
242237.120.128.0/17237.120.128.1 to 237.120.255.254237.120.255.25532,766
243237.121.0.0/17237.121.0.1 to 237.121.127.254237.121.127.25532,766
244237.121.128.0/17237.121.128.1 to 237.121.255.254237.121.255.25532,766
245237.122.0.0/17237.122.0.1 to 237.122.127.254237.122.127.25532,766
246237.122.128.0/17237.122.128.1 to 237.122.255.254237.122.255.25532,766
247237.123.0.0/17237.123.0.1 to 237.123.127.254237.123.127.25532,766
248237.123.128.0/17237.123.128.1 to 237.123.255.254237.123.255.25532,766
249237.124.0.0/17237.124.0.1 to 237.124.127.254237.124.127.25532,766
250237.124.128.0/17237.124.128.1 to 237.124.255.254237.124.255.25532,766
251237.125.0.0/17237.125.0.1 to 237.125.127.254237.125.127.25532,766
252237.125.128.0/17237.125.128.1 to 237.125.255.254237.125.255.25532,766
253237.126.0.0/17237.126.0.1 to 237.126.127.254237.126.127.25532,766
254237.126.128.0/17237.126.128.1 to 237.126.255.254237.126.255.25532,766
255237.127.0.0/17237.127.0.1 to 237.127.127.254237.127.127.25532,766
256237.127.128.0/17237.127.128.1 to 237.127.255.254237.127.255.25532,766

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.