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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.

Network151.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
151.0.0.0
Broadcast address
151.255.255.255
First usable
151.0.0.1
Last usable
151.255.255.254
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
Public public
Old class
B (default /16)
As numbers
Hex 97000000 · Integer 2533359616 to 2550136831
Reverse DNS zone
151.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010111..00000000.00000000.00000000151.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10010111..00000000.00000000.00000000151.0.0.0
Broadcast10010111..11111111.11111111.11111111151.255.255.255
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)

151.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1151.0.0.0/17151.0.0.1 to 151.0.127.254151.0.127.25532,766
2151.0.128.0/17151.0.128.1 to 151.0.255.254151.0.255.25532,766
3151.1.0.0/17151.1.0.1 to 151.1.127.254151.1.127.25532,766
4151.1.128.0/17151.1.128.1 to 151.1.255.254151.1.255.25532,766
5151.2.0.0/17151.2.0.1 to 151.2.127.254151.2.127.25532,766
6151.2.128.0/17151.2.128.1 to 151.2.255.254151.2.255.25532,766
7151.3.0.0/17151.3.0.1 to 151.3.127.254151.3.127.25532,766
8151.3.128.0/17151.3.128.1 to 151.3.255.254151.3.255.25532,766
9151.4.0.0/17151.4.0.1 to 151.4.127.254151.4.127.25532,766
10151.4.128.0/17151.4.128.1 to 151.4.255.254151.4.255.25532,766
11151.5.0.0/17151.5.0.1 to 151.5.127.254151.5.127.25532,766
12151.5.128.0/17151.5.128.1 to 151.5.255.254151.5.255.25532,766
13151.6.0.0/17151.6.0.1 to 151.6.127.254151.6.127.25532,766
14151.6.128.0/17151.6.128.1 to 151.6.255.254151.6.255.25532,766
15151.7.0.0/17151.7.0.1 to 151.7.127.254151.7.127.25532,766
16151.7.128.0/17151.7.128.1 to 151.7.255.254151.7.255.25532,766
17151.8.0.0/17151.8.0.1 to 151.8.127.254151.8.127.25532,766
18151.8.128.0/17151.8.128.1 to 151.8.255.254151.8.255.25532,766
19151.9.0.0/17151.9.0.1 to 151.9.127.254151.9.127.25532,766
20151.9.128.0/17151.9.128.1 to 151.9.255.254151.9.255.25532,766
21151.10.0.0/17151.10.0.1 to 151.10.127.254151.10.127.25532,766
22151.10.128.0/17151.10.128.1 to 151.10.255.254151.10.255.25532,766
23151.11.0.0/17151.11.0.1 to 151.11.127.254151.11.127.25532,766
24151.11.128.0/17151.11.128.1 to 151.11.255.254151.11.255.25532,766
25151.12.0.0/17151.12.0.1 to 151.12.127.254151.12.127.25532,766
26151.12.128.0/17151.12.128.1 to 151.12.255.254151.12.255.25532,766
27151.13.0.0/17151.13.0.1 to 151.13.127.254151.13.127.25532,766
28151.13.128.0/17151.13.128.1 to 151.13.255.254151.13.255.25532,766
29151.14.0.0/17151.14.0.1 to 151.14.127.254151.14.127.25532,766
30151.14.128.0/17151.14.128.1 to 151.14.255.254151.14.255.25532,766
31151.15.0.0/17151.15.0.1 to 151.15.127.254151.15.127.25532,766
32151.15.128.0/17151.15.128.1 to 151.15.255.254151.15.255.25532,766
33151.16.0.0/17151.16.0.1 to 151.16.127.254151.16.127.25532,766
34151.16.128.0/17151.16.128.1 to 151.16.255.254151.16.255.25532,766
35151.17.0.0/17151.17.0.1 to 151.17.127.254151.17.127.25532,766
36151.17.128.0/17151.17.128.1 to 151.17.255.254151.17.255.25532,766
37151.18.0.0/17151.18.0.1 to 151.18.127.254151.18.127.25532,766
38151.18.128.0/17151.18.128.1 to 151.18.255.254151.18.255.25532,766
39151.19.0.0/17151.19.0.1 to 151.19.127.254151.19.127.25532,766
40151.19.128.0/17151.19.128.1 to 151.19.255.254151.19.255.25532,766
41151.20.0.0/17151.20.0.1 to 151.20.127.254151.20.127.25532,766
42151.20.128.0/17151.20.128.1 to 151.20.255.254151.20.255.25532,766
43151.21.0.0/17151.21.0.1 to 151.21.127.254151.21.127.25532,766
44151.21.128.0/17151.21.128.1 to 151.21.255.254151.21.255.25532,766
45151.22.0.0/17151.22.0.1 to 151.22.127.254151.22.127.25532,766
46151.22.128.0/17151.22.128.1 to 151.22.255.254151.22.255.25532,766
47151.23.0.0/17151.23.0.1 to 151.23.127.254151.23.127.25532,766
48151.23.128.0/17151.23.128.1 to 151.23.255.254151.23.255.25532,766
49151.24.0.0/17151.24.0.1 to 151.24.127.254151.24.127.25532,766
50151.24.128.0/17151.24.128.1 to 151.24.255.254151.24.255.25532,766
51151.25.0.0/17151.25.0.1 to 151.25.127.254151.25.127.25532,766
52151.25.128.0/17151.25.128.1 to 151.25.255.254151.25.255.25532,766
53151.26.0.0/17151.26.0.1 to 151.26.127.254151.26.127.25532,766
54151.26.128.0/17151.26.128.1 to 151.26.255.254151.26.255.25532,766
55151.27.0.0/17151.27.0.1 to 151.27.127.254151.27.127.25532,766
56151.27.128.0/17151.27.128.1 to 151.27.255.254151.27.255.25532,766
57151.28.0.0/17151.28.0.1 to 151.28.127.254151.28.127.25532,766
58151.28.128.0/17151.28.128.1 to 151.28.255.254151.28.255.25532,766
59151.29.0.0/17151.29.0.1 to 151.29.127.254151.29.127.25532,766
60151.29.128.0/17151.29.128.1 to 151.29.255.254151.29.255.25532,766
61151.30.0.0/17151.30.0.1 to 151.30.127.254151.30.127.25532,766
62151.30.128.0/17151.30.128.1 to 151.30.255.254151.30.255.25532,766
63151.31.0.0/17151.31.0.1 to 151.31.127.254151.31.127.25532,766
64151.31.128.0/17151.31.128.1 to 151.31.255.254151.31.255.25532,766
65151.32.0.0/17151.32.0.1 to 151.32.127.254151.32.127.25532,766
66151.32.128.0/17151.32.128.1 to 151.32.255.254151.32.255.25532,766
67151.33.0.0/17151.33.0.1 to 151.33.127.254151.33.127.25532,766
68151.33.128.0/17151.33.128.1 to 151.33.255.254151.33.255.25532,766
69151.34.0.0/17151.34.0.1 to 151.34.127.254151.34.127.25532,766
70151.34.128.0/17151.34.128.1 to 151.34.255.254151.34.255.25532,766
71151.35.0.0/17151.35.0.1 to 151.35.127.254151.35.127.25532,766
72151.35.128.0/17151.35.128.1 to 151.35.255.254151.35.255.25532,766
73151.36.0.0/17151.36.0.1 to 151.36.127.254151.36.127.25532,766
74151.36.128.0/17151.36.128.1 to 151.36.255.254151.36.255.25532,766
75151.37.0.0/17151.37.0.1 to 151.37.127.254151.37.127.25532,766
76151.37.128.0/17151.37.128.1 to 151.37.255.254151.37.255.25532,766
77151.38.0.0/17151.38.0.1 to 151.38.127.254151.38.127.25532,766
78151.38.128.0/17151.38.128.1 to 151.38.255.254151.38.255.25532,766
79151.39.0.0/17151.39.0.1 to 151.39.127.254151.39.127.25532,766
80151.39.128.0/17151.39.128.1 to 151.39.255.254151.39.255.25532,766
81151.40.0.0/17151.40.0.1 to 151.40.127.254151.40.127.25532,766
82151.40.128.0/17151.40.128.1 to 151.40.255.254151.40.255.25532,766
83151.41.0.0/17151.41.0.1 to 151.41.127.254151.41.127.25532,766
84151.41.128.0/17151.41.128.1 to 151.41.255.254151.41.255.25532,766
85151.42.0.0/17151.42.0.1 to 151.42.127.254151.42.127.25532,766
86151.42.128.0/17151.42.128.1 to 151.42.255.254151.42.255.25532,766
87151.43.0.0/17151.43.0.1 to 151.43.127.254151.43.127.25532,766
88151.43.128.0/17151.43.128.1 to 151.43.255.254151.43.255.25532,766
89151.44.0.0/17151.44.0.1 to 151.44.127.254151.44.127.25532,766
90151.44.128.0/17151.44.128.1 to 151.44.255.254151.44.255.25532,766
91151.45.0.0/17151.45.0.1 to 151.45.127.254151.45.127.25532,766
92151.45.128.0/17151.45.128.1 to 151.45.255.254151.45.255.25532,766
93151.46.0.0/17151.46.0.1 to 151.46.127.254151.46.127.25532,766
94151.46.128.0/17151.46.128.1 to 151.46.255.254151.46.255.25532,766
95151.47.0.0/17151.47.0.1 to 151.47.127.254151.47.127.25532,766
96151.47.128.0/17151.47.128.1 to 151.47.255.254151.47.255.25532,766
97151.48.0.0/17151.48.0.1 to 151.48.127.254151.48.127.25532,766
98151.48.128.0/17151.48.128.1 to 151.48.255.254151.48.255.25532,766
99151.49.0.0/17151.49.0.1 to 151.49.127.254151.49.127.25532,766
100151.49.128.0/17151.49.128.1 to 151.49.255.254151.49.255.25532,766
101151.50.0.0/17151.50.0.1 to 151.50.127.254151.50.127.25532,766
102151.50.128.0/17151.50.128.1 to 151.50.255.254151.50.255.25532,766
103151.51.0.0/17151.51.0.1 to 151.51.127.254151.51.127.25532,766
104151.51.128.0/17151.51.128.1 to 151.51.255.254151.51.255.25532,766
105151.52.0.0/17151.52.0.1 to 151.52.127.254151.52.127.25532,766
106151.52.128.0/17151.52.128.1 to 151.52.255.254151.52.255.25532,766
107151.53.0.0/17151.53.0.1 to 151.53.127.254151.53.127.25532,766
108151.53.128.0/17151.53.128.1 to 151.53.255.254151.53.255.25532,766
109151.54.0.0/17151.54.0.1 to 151.54.127.254151.54.127.25532,766
110151.54.128.0/17151.54.128.1 to 151.54.255.254151.54.255.25532,766
111151.55.0.0/17151.55.0.1 to 151.55.127.254151.55.127.25532,766
112151.55.128.0/17151.55.128.1 to 151.55.255.254151.55.255.25532,766
113151.56.0.0/17151.56.0.1 to 151.56.127.254151.56.127.25532,766
114151.56.128.0/17151.56.128.1 to 151.56.255.254151.56.255.25532,766
115151.57.0.0/17151.57.0.1 to 151.57.127.254151.57.127.25532,766
116151.57.128.0/17151.57.128.1 to 151.57.255.254151.57.255.25532,766
117151.58.0.0/17151.58.0.1 to 151.58.127.254151.58.127.25532,766
118151.58.128.0/17151.58.128.1 to 151.58.255.254151.58.255.25532,766
119151.59.0.0/17151.59.0.1 to 151.59.127.254151.59.127.25532,766
120151.59.128.0/17151.59.128.1 to 151.59.255.254151.59.255.25532,766
121151.60.0.0/17151.60.0.1 to 151.60.127.254151.60.127.25532,766
122151.60.128.0/17151.60.128.1 to 151.60.255.254151.60.255.25532,766
123151.61.0.0/17151.61.0.1 to 151.61.127.254151.61.127.25532,766
124151.61.128.0/17151.61.128.1 to 151.61.255.254151.61.255.25532,766
125151.62.0.0/17151.62.0.1 to 151.62.127.254151.62.127.25532,766
126151.62.128.0/17151.62.128.1 to 151.62.255.254151.62.255.25532,766
127151.63.0.0/17151.63.0.1 to 151.63.127.254151.63.127.25532,766
128151.63.128.0/17151.63.128.1 to 151.63.255.254151.63.255.25532,766
129151.64.0.0/17151.64.0.1 to 151.64.127.254151.64.127.25532,766
130151.64.128.0/17151.64.128.1 to 151.64.255.254151.64.255.25532,766
131151.65.0.0/17151.65.0.1 to 151.65.127.254151.65.127.25532,766
132151.65.128.0/17151.65.128.1 to 151.65.255.254151.65.255.25532,766
133151.66.0.0/17151.66.0.1 to 151.66.127.254151.66.127.25532,766
134151.66.128.0/17151.66.128.1 to 151.66.255.254151.66.255.25532,766
135151.67.0.0/17151.67.0.1 to 151.67.127.254151.67.127.25532,766
136151.67.128.0/17151.67.128.1 to 151.67.255.254151.67.255.25532,766
137151.68.0.0/17151.68.0.1 to 151.68.127.254151.68.127.25532,766
138151.68.128.0/17151.68.128.1 to 151.68.255.254151.68.255.25532,766
139151.69.0.0/17151.69.0.1 to 151.69.127.254151.69.127.25532,766
140151.69.128.0/17151.69.128.1 to 151.69.255.254151.69.255.25532,766
141151.70.0.0/17151.70.0.1 to 151.70.127.254151.70.127.25532,766
142151.70.128.0/17151.70.128.1 to 151.70.255.254151.70.255.25532,766
143151.71.0.0/17151.71.0.1 to 151.71.127.254151.71.127.25532,766
144151.71.128.0/17151.71.128.1 to 151.71.255.254151.71.255.25532,766
145151.72.0.0/17151.72.0.1 to 151.72.127.254151.72.127.25532,766
146151.72.128.0/17151.72.128.1 to 151.72.255.254151.72.255.25532,766
147151.73.0.0/17151.73.0.1 to 151.73.127.254151.73.127.25532,766
148151.73.128.0/17151.73.128.1 to 151.73.255.254151.73.255.25532,766
149151.74.0.0/17151.74.0.1 to 151.74.127.254151.74.127.25532,766
150151.74.128.0/17151.74.128.1 to 151.74.255.254151.74.255.25532,766
151151.75.0.0/17151.75.0.1 to 151.75.127.254151.75.127.25532,766
152151.75.128.0/17151.75.128.1 to 151.75.255.254151.75.255.25532,766
153151.76.0.0/17151.76.0.1 to 151.76.127.254151.76.127.25532,766
154151.76.128.0/17151.76.128.1 to 151.76.255.254151.76.255.25532,766
155151.77.0.0/17151.77.0.1 to 151.77.127.254151.77.127.25532,766
156151.77.128.0/17151.77.128.1 to 151.77.255.254151.77.255.25532,766
157151.78.0.0/17151.78.0.1 to 151.78.127.254151.78.127.25532,766
158151.78.128.0/17151.78.128.1 to 151.78.255.254151.78.255.25532,766
159151.79.0.0/17151.79.0.1 to 151.79.127.254151.79.127.25532,766
160151.79.128.0/17151.79.128.1 to 151.79.255.254151.79.255.25532,766
161151.80.0.0/17151.80.0.1 to 151.80.127.254151.80.127.25532,766
162151.80.128.0/17151.80.128.1 to 151.80.255.254151.80.255.25532,766
163151.81.0.0/17151.81.0.1 to 151.81.127.254151.81.127.25532,766
164151.81.128.0/17151.81.128.1 to 151.81.255.254151.81.255.25532,766
165151.82.0.0/17151.82.0.1 to 151.82.127.254151.82.127.25532,766
166151.82.128.0/17151.82.128.1 to 151.82.255.254151.82.255.25532,766
167151.83.0.0/17151.83.0.1 to 151.83.127.254151.83.127.25532,766
168151.83.128.0/17151.83.128.1 to 151.83.255.254151.83.255.25532,766
169151.84.0.0/17151.84.0.1 to 151.84.127.254151.84.127.25532,766
170151.84.128.0/17151.84.128.1 to 151.84.255.254151.84.255.25532,766
171151.85.0.0/17151.85.0.1 to 151.85.127.254151.85.127.25532,766
172151.85.128.0/17151.85.128.1 to 151.85.255.254151.85.255.25532,766
173151.86.0.0/17151.86.0.1 to 151.86.127.254151.86.127.25532,766
174151.86.128.0/17151.86.128.1 to 151.86.255.254151.86.255.25532,766
175151.87.0.0/17151.87.0.1 to 151.87.127.254151.87.127.25532,766
176151.87.128.0/17151.87.128.1 to 151.87.255.254151.87.255.25532,766
177151.88.0.0/17151.88.0.1 to 151.88.127.254151.88.127.25532,766
178151.88.128.0/17151.88.128.1 to 151.88.255.254151.88.255.25532,766
179151.89.0.0/17151.89.0.1 to 151.89.127.254151.89.127.25532,766
180151.89.128.0/17151.89.128.1 to 151.89.255.254151.89.255.25532,766
181151.90.0.0/17151.90.0.1 to 151.90.127.254151.90.127.25532,766
182151.90.128.0/17151.90.128.1 to 151.90.255.254151.90.255.25532,766
183151.91.0.0/17151.91.0.1 to 151.91.127.254151.91.127.25532,766
184151.91.128.0/17151.91.128.1 to 151.91.255.254151.91.255.25532,766
185151.92.0.0/17151.92.0.1 to 151.92.127.254151.92.127.25532,766
186151.92.128.0/17151.92.128.1 to 151.92.255.254151.92.255.25532,766
187151.93.0.0/17151.93.0.1 to 151.93.127.254151.93.127.25532,766
188151.93.128.0/17151.93.128.1 to 151.93.255.254151.93.255.25532,766
189151.94.0.0/17151.94.0.1 to 151.94.127.254151.94.127.25532,766
190151.94.128.0/17151.94.128.1 to 151.94.255.254151.94.255.25532,766
191151.95.0.0/17151.95.0.1 to 151.95.127.254151.95.127.25532,766
192151.95.128.0/17151.95.128.1 to 151.95.255.254151.95.255.25532,766
193151.96.0.0/17151.96.0.1 to 151.96.127.254151.96.127.25532,766
194151.96.128.0/17151.96.128.1 to 151.96.255.254151.96.255.25532,766
195151.97.0.0/17151.97.0.1 to 151.97.127.254151.97.127.25532,766
196151.97.128.0/17151.97.128.1 to 151.97.255.254151.97.255.25532,766
197151.98.0.0/17151.98.0.1 to 151.98.127.254151.98.127.25532,766
198151.98.128.0/17151.98.128.1 to 151.98.255.254151.98.255.25532,766
199151.99.0.0/17151.99.0.1 to 151.99.127.254151.99.127.25532,766
200151.99.128.0/17151.99.128.1 to 151.99.255.254151.99.255.25532,766
201151.100.0.0/17151.100.0.1 to 151.100.127.254151.100.127.25532,766
202151.100.128.0/17151.100.128.1 to 151.100.255.254151.100.255.25532,766
203151.101.0.0/17151.101.0.1 to 151.101.127.254151.101.127.25532,766
204151.101.128.0/17151.101.128.1 to 151.101.255.254151.101.255.25532,766
205151.102.0.0/17151.102.0.1 to 151.102.127.254151.102.127.25532,766
206151.102.128.0/17151.102.128.1 to 151.102.255.254151.102.255.25532,766
207151.103.0.0/17151.103.0.1 to 151.103.127.254151.103.127.25532,766
208151.103.128.0/17151.103.128.1 to 151.103.255.254151.103.255.25532,766
209151.104.0.0/17151.104.0.1 to 151.104.127.254151.104.127.25532,766
210151.104.128.0/17151.104.128.1 to 151.104.255.254151.104.255.25532,766
211151.105.0.0/17151.105.0.1 to 151.105.127.254151.105.127.25532,766
212151.105.128.0/17151.105.128.1 to 151.105.255.254151.105.255.25532,766
213151.106.0.0/17151.106.0.1 to 151.106.127.254151.106.127.25532,766
214151.106.128.0/17151.106.128.1 to 151.106.255.254151.106.255.25532,766
215151.107.0.0/17151.107.0.1 to 151.107.127.254151.107.127.25532,766
216151.107.128.0/17151.107.128.1 to 151.107.255.254151.107.255.25532,766
217151.108.0.0/17151.108.0.1 to 151.108.127.254151.108.127.25532,766
218151.108.128.0/17151.108.128.1 to 151.108.255.254151.108.255.25532,766
219151.109.0.0/17151.109.0.1 to 151.109.127.254151.109.127.25532,766
220151.109.128.0/17151.109.128.1 to 151.109.255.254151.109.255.25532,766
221151.110.0.0/17151.110.0.1 to 151.110.127.254151.110.127.25532,766
222151.110.128.0/17151.110.128.1 to 151.110.255.254151.110.255.25532,766
223151.111.0.0/17151.111.0.1 to 151.111.127.254151.111.127.25532,766
224151.111.128.0/17151.111.128.1 to 151.111.255.254151.111.255.25532,766
225151.112.0.0/17151.112.0.1 to 151.112.127.254151.112.127.25532,766
226151.112.128.0/17151.112.128.1 to 151.112.255.254151.112.255.25532,766
227151.113.0.0/17151.113.0.1 to 151.113.127.254151.113.127.25532,766
228151.113.128.0/17151.113.128.1 to 151.113.255.254151.113.255.25532,766
229151.114.0.0/17151.114.0.1 to 151.114.127.254151.114.127.25532,766
230151.114.128.0/17151.114.128.1 to 151.114.255.254151.114.255.25532,766
231151.115.0.0/17151.115.0.1 to 151.115.127.254151.115.127.25532,766
232151.115.128.0/17151.115.128.1 to 151.115.255.254151.115.255.25532,766
233151.116.0.0/17151.116.0.1 to 151.116.127.254151.116.127.25532,766
234151.116.128.0/17151.116.128.1 to 151.116.255.254151.116.255.25532,766
235151.117.0.0/17151.117.0.1 to 151.117.127.254151.117.127.25532,766
236151.117.128.0/17151.117.128.1 to 151.117.255.254151.117.255.25532,766
237151.118.0.0/17151.118.0.1 to 151.118.127.254151.118.127.25532,766
238151.118.128.0/17151.118.128.1 to 151.118.255.254151.118.255.25532,766
239151.119.0.0/17151.119.0.1 to 151.119.127.254151.119.127.25532,766
240151.119.128.0/17151.119.128.1 to 151.119.255.254151.119.255.25532,766
241151.120.0.0/17151.120.0.1 to 151.120.127.254151.120.127.25532,766
242151.120.128.0/17151.120.128.1 to 151.120.255.254151.120.255.25532,766
243151.121.0.0/17151.121.0.1 to 151.121.127.254151.121.127.25532,766
244151.121.128.0/17151.121.128.1 to 151.121.255.254151.121.255.25532,766
245151.122.0.0/17151.122.0.1 to 151.122.127.254151.122.127.25532,766
246151.122.128.0/17151.122.128.1 to 151.122.255.254151.122.255.25532,766
247151.123.0.0/17151.123.0.1 to 151.123.127.254151.123.127.25532,766
248151.123.128.0/17151.123.128.1 to 151.123.255.254151.123.255.25532,766
249151.124.0.0/17151.124.0.1 to 151.124.127.254151.124.127.25532,766
250151.124.128.0/17151.124.128.1 to 151.124.255.254151.124.255.25532,766
251151.125.0.0/17151.125.0.1 to 151.125.127.254151.125.127.25532,766
252151.125.128.0/17151.125.128.1 to 151.125.255.254151.125.255.25532,766
253151.126.0.0/17151.126.0.1 to 151.126.127.254151.126.127.25532,766
254151.126.128.0/17151.126.128.1 to 151.126.255.254151.126.255.25532,766
255151.127.0.0/17151.127.0.1 to 151.127.127.254151.127.127.25532,766
256151.127.128.0/17151.127.128.1 to 151.127.255.254151.127.255.25532,766

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.