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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.

Network248.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
248.0.0.0
Broadcast address
255.255.255.255
First usable
248.0.0.1
Last usable
255.255.255.254
Usable hosts
134,217,726 (134,217,728 less the network and broadcast addresses)
Subnet mask
248.0.0.0
Wildcard mask
7.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/5
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F8000000 · Integer 4160749568 to 4294967295
Reverse DNS zones
248.in-addr.arpa
249.in-addr.arpa
250.in-addr.arpa
251.in-addr.arpa
252.in-addr.arpa
253.in-addr.arpa
254.in-addr.arpa
255.in-addr.arpa
/5 is not on a 8-bit boundary, so it takes 8 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111000.00000000.00000000.00000000248.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network11111000.00000000.00000000.00000000248.0.0.0
Broadcast11111111.11111111.11111111.11111111255.255.255.255
Split into smaller subnets/17
/6 (2)/7 (4)/8 (8)/9 (16)/10 (32)/11 (64)/12 (128)/13 (256)/14 (512)/15 (1,024)/16 (2,048)/17 (4,096)

248.0.0.0/5 makes 4,096 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1248.0.0.0/17248.0.0.1 to 248.0.127.254248.0.127.25532,766
2248.0.128.0/17248.0.128.1 to 248.0.255.254248.0.255.25532,766
3248.1.0.0/17248.1.0.1 to 248.1.127.254248.1.127.25532,766
4248.1.128.0/17248.1.128.1 to 248.1.255.254248.1.255.25532,766
5248.2.0.0/17248.2.0.1 to 248.2.127.254248.2.127.25532,766
6248.2.128.0/17248.2.128.1 to 248.2.255.254248.2.255.25532,766
7248.3.0.0/17248.3.0.1 to 248.3.127.254248.3.127.25532,766
8248.3.128.0/17248.3.128.1 to 248.3.255.254248.3.255.25532,766
9248.4.0.0/17248.4.0.1 to 248.4.127.254248.4.127.25532,766
10248.4.128.0/17248.4.128.1 to 248.4.255.254248.4.255.25532,766
11248.5.0.0/17248.5.0.1 to 248.5.127.254248.5.127.25532,766
12248.5.128.0/17248.5.128.1 to 248.5.255.254248.5.255.25532,766
13248.6.0.0/17248.6.0.1 to 248.6.127.254248.6.127.25532,766
14248.6.128.0/17248.6.128.1 to 248.6.255.254248.6.255.25532,766
15248.7.0.0/17248.7.0.1 to 248.7.127.254248.7.127.25532,766
16248.7.128.0/17248.7.128.1 to 248.7.255.254248.7.255.25532,766
17248.8.0.0/17248.8.0.1 to 248.8.127.254248.8.127.25532,766
18248.8.128.0/17248.8.128.1 to 248.8.255.254248.8.255.25532,766
19248.9.0.0/17248.9.0.1 to 248.9.127.254248.9.127.25532,766
20248.9.128.0/17248.9.128.1 to 248.9.255.254248.9.255.25532,766
21248.10.0.0/17248.10.0.1 to 248.10.127.254248.10.127.25532,766
22248.10.128.0/17248.10.128.1 to 248.10.255.254248.10.255.25532,766
23248.11.0.0/17248.11.0.1 to 248.11.127.254248.11.127.25532,766
24248.11.128.0/17248.11.128.1 to 248.11.255.254248.11.255.25532,766
25248.12.0.0/17248.12.0.1 to 248.12.127.254248.12.127.25532,766
26248.12.128.0/17248.12.128.1 to 248.12.255.254248.12.255.25532,766
27248.13.0.0/17248.13.0.1 to 248.13.127.254248.13.127.25532,766
28248.13.128.0/17248.13.128.1 to 248.13.255.254248.13.255.25532,766
29248.14.0.0/17248.14.0.1 to 248.14.127.254248.14.127.25532,766
30248.14.128.0/17248.14.128.1 to 248.14.255.254248.14.255.25532,766
31248.15.0.0/17248.15.0.1 to 248.15.127.254248.15.127.25532,766
32248.15.128.0/17248.15.128.1 to 248.15.255.254248.15.255.25532,766
33248.16.0.0/17248.16.0.1 to 248.16.127.254248.16.127.25532,766
34248.16.128.0/17248.16.128.1 to 248.16.255.254248.16.255.25532,766
35248.17.0.0/17248.17.0.1 to 248.17.127.254248.17.127.25532,766
36248.17.128.0/17248.17.128.1 to 248.17.255.254248.17.255.25532,766
37248.18.0.0/17248.18.0.1 to 248.18.127.254248.18.127.25532,766
38248.18.128.0/17248.18.128.1 to 248.18.255.254248.18.255.25532,766
39248.19.0.0/17248.19.0.1 to 248.19.127.254248.19.127.25532,766
40248.19.128.0/17248.19.128.1 to 248.19.255.254248.19.255.25532,766
41248.20.0.0/17248.20.0.1 to 248.20.127.254248.20.127.25532,766
42248.20.128.0/17248.20.128.1 to 248.20.255.254248.20.255.25532,766
43248.21.0.0/17248.21.0.1 to 248.21.127.254248.21.127.25532,766
44248.21.128.0/17248.21.128.1 to 248.21.255.254248.21.255.25532,766
45248.22.0.0/17248.22.0.1 to 248.22.127.254248.22.127.25532,766
46248.22.128.0/17248.22.128.1 to 248.22.255.254248.22.255.25532,766
47248.23.0.0/17248.23.0.1 to 248.23.127.254248.23.127.25532,766
48248.23.128.0/17248.23.128.1 to 248.23.255.254248.23.255.25532,766
49248.24.0.0/17248.24.0.1 to 248.24.127.254248.24.127.25532,766
50248.24.128.0/17248.24.128.1 to 248.24.255.254248.24.255.25532,766
51248.25.0.0/17248.25.0.1 to 248.25.127.254248.25.127.25532,766
52248.25.128.0/17248.25.128.1 to 248.25.255.254248.25.255.25532,766
53248.26.0.0/17248.26.0.1 to 248.26.127.254248.26.127.25532,766
54248.26.128.0/17248.26.128.1 to 248.26.255.254248.26.255.25532,766
55248.27.0.0/17248.27.0.1 to 248.27.127.254248.27.127.25532,766
56248.27.128.0/17248.27.128.1 to 248.27.255.254248.27.255.25532,766
57248.28.0.0/17248.28.0.1 to 248.28.127.254248.28.127.25532,766
58248.28.128.0/17248.28.128.1 to 248.28.255.254248.28.255.25532,766
59248.29.0.0/17248.29.0.1 to 248.29.127.254248.29.127.25532,766
60248.29.128.0/17248.29.128.1 to 248.29.255.254248.29.255.25532,766
61248.30.0.0/17248.30.0.1 to 248.30.127.254248.30.127.25532,766
62248.30.128.0/17248.30.128.1 to 248.30.255.254248.30.255.25532,766
63248.31.0.0/17248.31.0.1 to 248.31.127.254248.31.127.25532,766
64248.31.128.0/17248.31.128.1 to 248.31.255.254248.31.255.25532,766
65248.32.0.0/17248.32.0.1 to 248.32.127.254248.32.127.25532,766
66248.32.128.0/17248.32.128.1 to 248.32.255.254248.32.255.25532,766
67248.33.0.0/17248.33.0.1 to 248.33.127.254248.33.127.25532,766
68248.33.128.0/17248.33.128.1 to 248.33.255.254248.33.255.25532,766
69248.34.0.0/17248.34.0.1 to 248.34.127.254248.34.127.25532,766
70248.34.128.0/17248.34.128.1 to 248.34.255.254248.34.255.25532,766
71248.35.0.0/17248.35.0.1 to 248.35.127.254248.35.127.25532,766
72248.35.128.0/17248.35.128.1 to 248.35.255.254248.35.255.25532,766
73248.36.0.0/17248.36.0.1 to 248.36.127.254248.36.127.25532,766
74248.36.128.0/17248.36.128.1 to 248.36.255.254248.36.255.25532,766
75248.37.0.0/17248.37.0.1 to 248.37.127.254248.37.127.25532,766
76248.37.128.0/17248.37.128.1 to 248.37.255.254248.37.255.25532,766
77248.38.0.0/17248.38.0.1 to 248.38.127.254248.38.127.25532,766
78248.38.128.0/17248.38.128.1 to 248.38.255.254248.38.255.25532,766
79248.39.0.0/17248.39.0.1 to 248.39.127.254248.39.127.25532,766
80248.39.128.0/17248.39.128.1 to 248.39.255.254248.39.255.25532,766
81248.40.0.0/17248.40.0.1 to 248.40.127.254248.40.127.25532,766
82248.40.128.0/17248.40.128.1 to 248.40.255.254248.40.255.25532,766
83248.41.0.0/17248.41.0.1 to 248.41.127.254248.41.127.25532,766
84248.41.128.0/17248.41.128.1 to 248.41.255.254248.41.255.25532,766
85248.42.0.0/17248.42.0.1 to 248.42.127.254248.42.127.25532,766
86248.42.128.0/17248.42.128.1 to 248.42.255.254248.42.255.25532,766
87248.43.0.0/17248.43.0.1 to 248.43.127.254248.43.127.25532,766
88248.43.128.0/17248.43.128.1 to 248.43.255.254248.43.255.25532,766
89248.44.0.0/17248.44.0.1 to 248.44.127.254248.44.127.25532,766
90248.44.128.0/17248.44.128.1 to 248.44.255.254248.44.255.25532,766
91248.45.0.0/17248.45.0.1 to 248.45.127.254248.45.127.25532,766
92248.45.128.0/17248.45.128.1 to 248.45.255.254248.45.255.25532,766
93248.46.0.0/17248.46.0.1 to 248.46.127.254248.46.127.25532,766
94248.46.128.0/17248.46.128.1 to 248.46.255.254248.46.255.25532,766
95248.47.0.0/17248.47.0.1 to 248.47.127.254248.47.127.25532,766
96248.47.128.0/17248.47.128.1 to 248.47.255.254248.47.255.25532,766
97248.48.0.0/17248.48.0.1 to 248.48.127.254248.48.127.25532,766
98248.48.128.0/17248.48.128.1 to 248.48.255.254248.48.255.25532,766
99248.49.0.0/17248.49.0.1 to 248.49.127.254248.49.127.25532,766
100248.49.128.0/17248.49.128.1 to 248.49.255.254248.49.255.25532,766
101248.50.0.0/17248.50.0.1 to 248.50.127.254248.50.127.25532,766
102248.50.128.0/17248.50.128.1 to 248.50.255.254248.50.255.25532,766
103248.51.0.0/17248.51.0.1 to 248.51.127.254248.51.127.25532,766
104248.51.128.0/17248.51.128.1 to 248.51.255.254248.51.255.25532,766
105248.52.0.0/17248.52.0.1 to 248.52.127.254248.52.127.25532,766
106248.52.128.0/17248.52.128.1 to 248.52.255.254248.52.255.25532,766
107248.53.0.0/17248.53.0.1 to 248.53.127.254248.53.127.25532,766
108248.53.128.0/17248.53.128.1 to 248.53.255.254248.53.255.25532,766
109248.54.0.0/17248.54.0.1 to 248.54.127.254248.54.127.25532,766
110248.54.128.0/17248.54.128.1 to 248.54.255.254248.54.255.25532,766
111248.55.0.0/17248.55.0.1 to 248.55.127.254248.55.127.25532,766
112248.55.128.0/17248.55.128.1 to 248.55.255.254248.55.255.25532,766
113248.56.0.0/17248.56.0.1 to 248.56.127.254248.56.127.25532,766
114248.56.128.0/17248.56.128.1 to 248.56.255.254248.56.255.25532,766
115248.57.0.0/17248.57.0.1 to 248.57.127.254248.57.127.25532,766
116248.57.128.0/17248.57.128.1 to 248.57.255.254248.57.255.25532,766
117248.58.0.0/17248.58.0.1 to 248.58.127.254248.58.127.25532,766
118248.58.128.0/17248.58.128.1 to 248.58.255.254248.58.255.25532,766
119248.59.0.0/17248.59.0.1 to 248.59.127.254248.59.127.25532,766
120248.59.128.0/17248.59.128.1 to 248.59.255.254248.59.255.25532,766
121248.60.0.0/17248.60.0.1 to 248.60.127.254248.60.127.25532,766
122248.60.128.0/17248.60.128.1 to 248.60.255.254248.60.255.25532,766
123248.61.0.0/17248.61.0.1 to 248.61.127.254248.61.127.25532,766
124248.61.128.0/17248.61.128.1 to 248.61.255.254248.61.255.25532,766
125248.62.0.0/17248.62.0.1 to 248.62.127.254248.62.127.25532,766
126248.62.128.0/17248.62.128.1 to 248.62.255.254248.62.255.25532,766
127248.63.0.0/17248.63.0.1 to 248.63.127.254248.63.127.25532,766
128248.63.128.0/17248.63.128.1 to 248.63.255.254248.63.255.25532,766
129248.64.0.0/17248.64.0.1 to 248.64.127.254248.64.127.25532,766
130248.64.128.0/17248.64.128.1 to 248.64.255.254248.64.255.25532,766
131248.65.0.0/17248.65.0.1 to 248.65.127.254248.65.127.25532,766
132248.65.128.0/17248.65.128.1 to 248.65.255.254248.65.255.25532,766
133248.66.0.0/17248.66.0.1 to 248.66.127.254248.66.127.25532,766
134248.66.128.0/17248.66.128.1 to 248.66.255.254248.66.255.25532,766
135248.67.0.0/17248.67.0.1 to 248.67.127.254248.67.127.25532,766
136248.67.128.0/17248.67.128.1 to 248.67.255.254248.67.255.25532,766
137248.68.0.0/17248.68.0.1 to 248.68.127.254248.68.127.25532,766
138248.68.128.0/17248.68.128.1 to 248.68.255.254248.68.255.25532,766
139248.69.0.0/17248.69.0.1 to 248.69.127.254248.69.127.25532,766
140248.69.128.0/17248.69.128.1 to 248.69.255.254248.69.255.25532,766
141248.70.0.0/17248.70.0.1 to 248.70.127.254248.70.127.25532,766
142248.70.128.0/17248.70.128.1 to 248.70.255.254248.70.255.25532,766
143248.71.0.0/17248.71.0.1 to 248.71.127.254248.71.127.25532,766
144248.71.128.0/17248.71.128.1 to 248.71.255.254248.71.255.25532,766
145248.72.0.0/17248.72.0.1 to 248.72.127.254248.72.127.25532,766
146248.72.128.0/17248.72.128.1 to 248.72.255.254248.72.255.25532,766
147248.73.0.0/17248.73.0.1 to 248.73.127.254248.73.127.25532,766
148248.73.128.0/17248.73.128.1 to 248.73.255.254248.73.255.25532,766
149248.74.0.0/17248.74.0.1 to 248.74.127.254248.74.127.25532,766
150248.74.128.0/17248.74.128.1 to 248.74.255.254248.74.255.25532,766
151248.75.0.0/17248.75.0.1 to 248.75.127.254248.75.127.25532,766
152248.75.128.0/17248.75.128.1 to 248.75.255.254248.75.255.25532,766
153248.76.0.0/17248.76.0.1 to 248.76.127.254248.76.127.25532,766
154248.76.128.0/17248.76.128.1 to 248.76.255.254248.76.255.25532,766
155248.77.0.0/17248.77.0.1 to 248.77.127.254248.77.127.25532,766
156248.77.128.0/17248.77.128.1 to 248.77.255.254248.77.255.25532,766
157248.78.0.0/17248.78.0.1 to 248.78.127.254248.78.127.25532,766
158248.78.128.0/17248.78.128.1 to 248.78.255.254248.78.255.25532,766
159248.79.0.0/17248.79.0.1 to 248.79.127.254248.79.127.25532,766
160248.79.128.0/17248.79.128.1 to 248.79.255.254248.79.255.25532,766
161248.80.0.0/17248.80.0.1 to 248.80.127.254248.80.127.25532,766
162248.80.128.0/17248.80.128.1 to 248.80.255.254248.80.255.25532,766
163248.81.0.0/17248.81.0.1 to 248.81.127.254248.81.127.25532,766
164248.81.128.0/17248.81.128.1 to 248.81.255.254248.81.255.25532,766
165248.82.0.0/17248.82.0.1 to 248.82.127.254248.82.127.25532,766
166248.82.128.0/17248.82.128.1 to 248.82.255.254248.82.255.25532,766
167248.83.0.0/17248.83.0.1 to 248.83.127.254248.83.127.25532,766
168248.83.128.0/17248.83.128.1 to 248.83.255.254248.83.255.25532,766
169248.84.0.0/17248.84.0.1 to 248.84.127.254248.84.127.25532,766
170248.84.128.0/17248.84.128.1 to 248.84.255.254248.84.255.25532,766
171248.85.0.0/17248.85.0.1 to 248.85.127.254248.85.127.25532,766
172248.85.128.0/17248.85.128.1 to 248.85.255.254248.85.255.25532,766
173248.86.0.0/17248.86.0.1 to 248.86.127.254248.86.127.25532,766
174248.86.128.0/17248.86.128.1 to 248.86.255.254248.86.255.25532,766
175248.87.0.0/17248.87.0.1 to 248.87.127.254248.87.127.25532,766
176248.87.128.0/17248.87.128.1 to 248.87.255.254248.87.255.25532,766
177248.88.0.0/17248.88.0.1 to 248.88.127.254248.88.127.25532,766
178248.88.128.0/17248.88.128.1 to 248.88.255.254248.88.255.25532,766
179248.89.0.0/17248.89.0.1 to 248.89.127.254248.89.127.25532,766
180248.89.128.0/17248.89.128.1 to 248.89.255.254248.89.255.25532,766
181248.90.0.0/17248.90.0.1 to 248.90.127.254248.90.127.25532,766
182248.90.128.0/17248.90.128.1 to 248.90.255.254248.90.255.25532,766
183248.91.0.0/17248.91.0.1 to 248.91.127.254248.91.127.25532,766
184248.91.128.0/17248.91.128.1 to 248.91.255.254248.91.255.25532,766
185248.92.0.0/17248.92.0.1 to 248.92.127.254248.92.127.25532,766
186248.92.128.0/17248.92.128.1 to 248.92.255.254248.92.255.25532,766
187248.93.0.0/17248.93.0.1 to 248.93.127.254248.93.127.25532,766
188248.93.128.0/17248.93.128.1 to 248.93.255.254248.93.255.25532,766
189248.94.0.0/17248.94.0.1 to 248.94.127.254248.94.127.25532,766
190248.94.128.0/17248.94.128.1 to 248.94.255.254248.94.255.25532,766
191248.95.0.0/17248.95.0.1 to 248.95.127.254248.95.127.25532,766
192248.95.128.0/17248.95.128.1 to 248.95.255.254248.95.255.25532,766
193248.96.0.0/17248.96.0.1 to 248.96.127.254248.96.127.25532,766
194248.96.128.0/17248.96.128.1 to 248.96.255.254248.96.255.25532,766
195248.97.0.0/17248.97.0.1 to 248.97.127.254248.97.127.25532,766
196248.97.128.0/17248.97.128.1 to 248.97.255.254248.97.255.25532,766
197248.98.0.0/17248.98.0.1 to 248.98.127.254248.98.127.25532,766
198248.98.128.0/17248.98.128.1 to 248.98.255.254248.98.255.25532,766
199248.99.0.0/17248.99.0.1 to 248.99.127.254248.99.127.25532,766
200248.99.128.0/17248.99.128.1 to 248.99.255.254248.99.255.25532,766
201248.100.0.0/17248.100.0.1 to 248.100.127.254248.100.127.25532,766
202248.100.128.0/17248.100.128.1 to 248.100.255.254248.100.255.25532,766
203248.101.0.0/17248.101.0.1 to 248.101.127.254248.101.127.25532,766
204248.101.128.0/17248.101.128.1 to 248.101.255.254248.101.255.25532,766
205248.102.0.0/17248.102.0.1 to 248.102.127.254248.102.127.25532,766
206248.102.128.0/17248.102.128.1 to 248.102.255.254248.102.255.25532,766
207248.103.0.0/17248.103.0.1 to 248.103.127.254248.103.127.25532,766
208248.103.128.0/17248.103.128.1 to 248.103.255.254248.103.255.25532,766
209248.104.0.0/17248.104.0.1 to 248.104.127.254248.104.127.25532,766
210248.104.128.0/17248.104.128.1 to 248.104.255.254248.104.255.25532,766
211248.105.0.0/17248.105.0.1 to 248.105.127.254248.105.127.25532,766
212248.105.128.0/17248.105.128.1 to 248.105.255.254248.105.255.25532,766
213248.106.0.0/17248.106.0.1 to 248.106.127.254248.106.127.25532,766
214248.106.128.0/17248.106.128.1 to 248.106.255.254248.106.255.25532,766
215248.107.0.0/17248.107.0.1 to 248.107.127.254248.107.127.25532,766
216248.107.128.0/17248.107.128.1 to 248.107.255.254248.107.255.25532,766
217248.108.0.0/17248.108.0.1 to 248.108.127.254248.108.127.25532,766
218248.108.128.0/17248.108.128.1 to 248.108.255.254248.108.255.25532,766
219248.109.0.0/17248.109.0.1 to 248.109.127.254248.109.127.25532,766
220248.109.128.0/17248.109.128.1 to 248.109.255.254248.109.255.25532,766
221248.110.0.0/17248.110.0.1 to 248.110.127.254248.110.127.25532,766
222248.110.128.0/17248.110.128.1 to 248.110.255.254248.110.255.25532,766
223248.111.0.0/17248.111.0.1 to 248.111.127.254248.111.127.25532,766
224248.111.128.0/17248.111.128.1 to 248.111.255.254248.111.255.25532,766
225248.112.0.0/17248.112.0.1 to 248.112.127.254248.112.127.25532,766
226248.112.128.0/17248.112.128.1 to 248.112.255.254248.112.255.25532,766
227248.113.0.0/17248.113.0.1 to 248.113.127.254248.113.127.25532,766
228248.113.128.0/17248.113.128.1 to 248.113.255.254248.113.255.25532,766
229248.114.0.0/17248.114.0.1 to 248.114.127.254248.114.127.25532,766
230248.114.128.0/17248.114.128.1 to 248.114.255.254248.114.255.25532,766
231248.115.0.0/17248.115.0.1 to 248.115.127.254248.115.127.25532,766
232248.115.128.0/17248.115.128.1 to 248.115.255.254248.115.255.25532,766
233248.116.0.0/17248.116.0.1 to 248.116.127.254248.116.127.25532,766
234248.116.128.0/17248.116.128.1 to 248.116.255.254248.116.255.25532,766
235248.117.0.0/17248.117.0.1 to 248.117.127.254248.117.127.25532,766
236248.117.128.0/17248.117.128.1 to 248.117.255.254248.117.255.25532,766
237248.118.0.0/17248.118.0.1 to 248.118.127.254248.118.127.25532,766
238248.118.128.0/17248.118.128.1 to 248.118.255.254248.118.255.25532,766
239248.119.0.0/17248.119.0.1 to 248.119.127.254248.119.127.25532,766
240248.119.128.0/17248.119.128.1 to 248.119.255.254248.119.255.25532,766
241248.120.0.0/17248.120.0.1 to 248.120.127.254248.120.127.25532,766
242248.120.128.0/17248.120.128.1 to 248.120.255.254248.120.255.25532,766
243248.121.0.0/17248.121.0.1 to 248.121.127.254248.121.127.25532,766
244248.121.128.0/17248.121.128.1 to 248.121.255.254248.121.255.25532,766
245248.122.0.0/17248.122.0.1 to 248.122.127.254248.122.127.25532,766
246248.122.128.0/17248.122.128.1 to 248.122.255.254248.122.255.25532,766
247248.123.0.0/17248.123.0.1 to 248.123.127.254248.123.127.25532,766
248248.123.128.0/17248.123.128.1 to 248.123.255.254248.123.255.25532,766
249248.124.0.0/17248.124.0.1 to 248.124.127.254248.124.127.25532,766
250248.124.128.0/17248.124.128.1 to 248.124.255.254248.124.255.25532,766
251248.125.0.0/17248.125.0.1 to 248.125.127.254248.125.127.25532,766
252248.125.128.0/17248.125.128.1 to 248.125.255.254248.125.255.25532,766
253248.126.0.0/17248.126.0.1 to 248.126.127.254248.126.127.25532,766
254248.126.128.0/17248.126.128.1 to 248.126.255.254248.126.255.25532,766
255248.127.0.0/17248.127.0.1 to 248.127.127.254248.127.127.25532,766
256248.127.128.0/17248.127.128.1 to 248.127.255.254248.127.255.25532,766

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.