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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.

Network247.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
247.0.0.0
Broadcast address
247.255.255.255
First usable
247.0.0.1
Last usable
247.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F7000000 · Integer 4143972352 to 4160749567
Reverse DNS zone
247.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110111..00000000.00000000.00000000247.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11110111..00000000.00000000.00000000247.0.0.0
Broadcast11110111..11111111.11111111.11111111247.255.255.255
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)

247.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1247.0.0.0/17247.0.0.1 to 247.0.127.254247.0.127.25532,766
2247.0.128.0/17247.0.128.1 to 247.0.255.254247.0.255.25532,766
3247.1.0.0/17247.1.0.1 to 247.1.127.254247.1.127.25532,766
4247.1.128.0/17247.1.128.1 to 247.1.255.254247.1.255.25532,766
5247.2.0.0/17247.2.0.1 to 247.2.127.254247.2.127.25532,766
6247.2.128.0/17247.2.128.1 to 247.2.255.254247.2.255.25532,766
7247.3.0.0/17247.3.0.1 to 247.3.127.254247.3.127.25532,766
8247.3.128.0/17247.3.128.1 to 247.3.255.254247.3.255.25532,766
9247.4.0.0/17247.4.0.1 to 247.4.127.254247.4.127.25532,766
10247.4.128.0/17247.4.128.1 to 247.4.255.254247.4.255.25532,766
11247.5.0.0/17247.5.0.1 to 247.5.127.254247.5.127.25532,766
12247.5.128.0/17247.5.128.1 to 247.5.255.254247.5.255.25532,766
13247.6.0.0/17247.6.0.1 to 247.6.127.254247.6.127.25532,766
14247.6.128.0/17247.6.128.1 to 247.6.255.254247.6.255.25532,766
15247.7.0.0/17247.7.0.1 to 247.7.127.254247.7.127.25532,766
16247.7.128.0/17247.7.128.1 to 247.7.255.254247.7.255.25532,766
17247.8.0.0/17247.8.0.1 to 247.8.127.254247.8.127.25532,766
18247.8.128.0/17247.8.128.1 to 247.8.255.254247.8.255.25532,766
19247.9.0.0/17247.9.0.1 to 247.9.127.254247.9.127.25532,766
20247.9.128.0/17247.9.128.1 to 247.9.255.254247.9.255.25532,766
21247.10.0.0/17247.10.0.1 to 247.10.127.254247.10.127.25532,766
22247.10.128.0/17247.10.128.1 to 247.10.255.254247.10.255.25532,766
23247.11.0.0/17247.11.0.1 to 247.11.127.254247.11.127.25532,766
24247.11.128.0/17247.11.128.1 to 247.11.255.254247.11.255.25532,766
25247.12.0.0/17247.12.0.1 to 247.12.127.254247.12.127.25532,766
26247.12.128.0/17247.12.128.1 to 247.12.255.254247.12.255.25532,766
27247.13.0.0/17247.13.0.1 to 247.13.127.254247.13.127.25532,766
28247.13.128.0/17247.13.128.1 to 247.13.255.254247.13.255.25532,766
29247.14.0.0/17247.14.0.1 to 247.14.127.254247.14.127.25532,766
30247.14.128.0/17247.14.128.1 to 247.14.255.254247.14.255.25532,766
31247.15.0.0/17247.15.0.1 to 247.15.127.254247.15.127.25532,766
32247.15.128.0/17247.15.128.1 to 247.15.255.254247.15.255.25532,766
33247.16.0.0/17247.16.0.1 to 247.16.127.254247.16.127.25532,766
34247.16.128.0/17247.16.128.1 to 247.16.255.254247.16.255.25532,766
35247.17.0.0/17247.17.0.1 to 247.17.127.254247.17.127.25532,766
36247.17.128.0/17247.17.128.1 to 247.17.255.254247.17.255.25532,766
37247.18.0.0/17247.18.0.1 to 247.18.127.254247.18.127.25532,766
38247.18.128.0/17247.18.128.1 to 247.18.255.254247.18.255.25532,766
39247.19.0.0/17247.19.0.1 to 247.19.127.254247.19.127.25532,766
40247.19.128.0/17247.19.128.1 to 247.19.255.254247.19.255.25532,766
41247.20.0.0/17247.20.0.1 to 247.20.127.254247.20.127.25532,766
42247.20.128.0/17247.20.128.1 to 247.20.255.254247.20.255.25532,766
43247.21.0.0/17247.21.0.1 to 247.21.127.254247.21.127.25532,766
44247.21.128.0/17247.21.128.1 to 247.21.255.254247.21.255.25532,766
45247.22.0.0/17247.22.0.1 to 247.22.127.254247.22.127.25532,766
46247.22.128.0/17247.22.128.1 to 247.22.255.254247.22.255.25532,766
47247.23.0.0/17247.23.0.1 to 247.23.127.254247.23.127.25532,766
48247.23.128.0/17247.23.128.1 to 247.23.255.254247.23.255.25532,766
49247.24.0.0/17247.24.0.1 to 247.24.127.254247.24.127.25532,766
50247.24.128.0/17247.24.128.1 to 247.24.255.254247.24.255.25532,766
51247.25.0.0/17247.25.0.1 to 247.25.127.254247.25.127.25532,766
52247.25.128.0/17247.25.128.1 to 247.25.255.254247.25.255.25532,766
53247.26.0.0/17247.26.0.1 to 247.26.127.254247.26.127.25532,766
54247.26.128.0/17247.26.128.1 to 247.26.255.254247.26.255.25532,766
55247.27.0.0/17247.27.0.1 to 247.27.127.254247.27.127.25532,766
56247.27.128.0/17247.27.128.1 to 247.27.255.254247.27.255.25532,766
57247.28.0.0/17247.28.0.1 to 247.28.127.254247.28.127.25532,766
58247.28.128.0/17247.28.128.1 to 247.28.255.254247.28.255.25532,766
59247.29.0.0/17247.29.0.1 to 247.29.127.254247.29.127.25532,766
60247.29.128.0/17247.29.128.1 to 247.29.255.254247.29.255.25532,766
61247.30.0.0/17247.30.0.1 to 247.30.127.254247.30.127.25532,766
62247.30.128.0/17247.30.128.1 to 247.30.255.254247.30.255.25532,766
63247.31.0.0/17247.31.0.1 to 247.31.127.254247.31.127.25532,766
64247.31.128.0/17247.31.128.1 to 247.31.255.254247.31.255.25532,766
65247.32.0.0/17247.32.0.1 to 247.32.127.254247.32.127.25532,766
66247.32.128.0/17247.32.128.1 to 247.32.255.254247.32.255.25532,766
67247.33.0.0/17247.33.0.1 to 247.33.127.254247.33.127.25532,766
68247.33.128.0/17247.33.128.1 to 247.33.255.254247.33.255.25532,766
69247.34.0.0/17247.34.0.1 to 247.34.127.254247.34.127.25532,766
70247.34.128.0/17247.34.128.1 to 247.34.255.254247.34.255.25532,766
71247.35.0.0/17247.35.0.1 to 247.35.127.254247.35.127.25532,766
72247.35.128.0/17247.35.128.1 to 247.35.255.254247.35.255.25532,766
73247.36.0.0/17247.36.0.1 to 247.36.127.254247.36.127.25532,766
74247.36.128.0/17247.36.128.1 to 247.36.255.254247.36.255.25532,766
75247.37.0.0/17247.37.0.1 to 247.37.127.254247.37.127.25532,766
76247.37.128.0/17247.37.128.1 to 247.37.255.254247.37.255.25532,766
77247.38.0.0/17247.38.0.1 to 247.38.127.254247.38.127.25532,766
78247.38.128.0/17247.38.128.1 to 247.38.255.254247.38.255.25532,766
79247.39.0.0/17247.39.0.1 to 247.39.127.254247.39.127.25532,766
80247.39.128.0/17247.39.128.1 to 247.39.255.254247.39.255.25532,766
81247.40.0.0/17247.40.0.1 to 247.40.127.254247.40.127.25532,766
82247.40.128.0/17247.40.128.1 to 247.40.255.254247.40.255.25532,766
83247.41.0.0/17247.41.0.1 to 247.41.127.254247.41.127.25532,766
84247.41.128.0/17247.41.128.1 to 247.41.255.254247.41.255.25532,766
85247.42.0.0/17247.42.0.1 to 247.42.127.254247.42.127.25532,766
86247.42.128.0/17247.42.128.1 to 247.42.255.254247.42.255.25532,766
87247.43.0.0/17247.43.0.1 to 247.43.127.254247.43.127.25532,766
88247.43.128.0/17247.43.128.1 to 247.43.255.254247.43.255.25532,766
89247.44.0.0/17247.44.0.1 to 247.44.127.254247.44.127.25532,766
90247.44.128.0/17247.44.128.1 to 247.44.255.254247.44.255.25532,766
91247.45.0.0/17247.45.0.1 to 247.45.127.254247.45.127.25532,766
92247.45.128.0/17247.45.128.1 to 247.45.255.254247.45.255.25532,766
93247.46.0.0/17247.46.0.1 to 247.46.127.254247.46.127.25532,766
94247.46.128.0/17247.46.128.1 to 247.46.255.254247.46.255.25532,766
95247.47.0.0/17247.47.0.1 to 247.47.127.254247.47.127.25532,766
96247.47.128.0/17247.47.128.1 to 247.47.255.254247.47.255.25532,766
97247.48.0.0/17247.48.0.1 to 247.48.127.254247.48.127.25532,766
98247.48.128.0/17247.48.128.1 to 247.48.255.254247.48.255.25532,766
99247.49.0.0/17247.49.0.1 to 247.49.127.254247.49.127.25532,766
100247.49.128.0/17247.49.128.1 to 247.49.255.254247.49.255.25532,766
101247.50.0.0/17247.50.0.1 to 247.50.127.254247.50.127.25532,766
102247.50.128.0/17247.50.128.1 to 247.50.255.254247.50.255.25532,766
103247.51.0.0/17247.51.0.1 to 247.51.127.254247.51.127.25532,766
104247.51.128.0/17247.51.128.1 to 247.51.255.254247.51.255.25532,766
105247.52.0.0/17247.52.0.1 to 247.52.127.254247.52.127.25532,766
106247.52.128.0/17247.52.128.1 to 247.52.255.254247.52.255.25532,766
107247.53.0.0/17247.53.0.1 to 247.53.127.254247.53.127.25532,766
108247.53.128.0/17247.53.128.1 to 247.53.255.254247.53.255.25532,766
109247.54.0.0/17247.54.0.1 to 247.54.127.254247.54.127.25532,766
110247.54.128.0/17247.54.128.1 to 247.54.255.254247.54.255.25532,766
111247.55.0.0/17247.55.0.1 to 247.55.127.254247.55.127.25532,766
112247.55.128.0/17247.55.128.1 to 247.55.255.254247.55.255.25532,766
113247.56.0.0/17247.56.0.1 to 247.56.127.254247.56.127.25532,766
114247.56.128.0/17247.56.128.1 to 247.56.255.254247.56.255.25532,766
115247.57.0.0/17247.57.0.1 to 247.57.127.254247.57.127.25532,766
116247.57.128.0/17247.57.128.1 to 247.57.255.254247.57.255.25532,766
117247.58.0.0/17247.58.0.1 to 247.58.127.254247.58.127.25532,766
118247.58.128.0/17247.58.128.1 to 247.58.255.254247.58.255.25532,766
119247.59.0.0/17247.59.0.1 to 247.59.127.254247.59.127.25532,766
120247.59.128.0/17247.59.128.1 to 247.59.255.254247.59.255.25532,766
121247.60.0.0/17247.60.0.1 to 247.60.127.254247.60.127.25532,766
122247.60.128.0/17247.60.128.1 to 247.60.255.254247.60.255.25532,766
123247.61.0.0/17247.61.0.1 to 247.61.127.254247.61.127.25532,766
124247.61.128.0/17247.61.128.1 to 247.61.255.254247.61.255.25532,766
125247.62.0.0/17247.62.0.1 to 247.62.127.254247.62.127.25532,766
126247.62.128.0/17247.62.128.1 to 247.62.255.254247.62.255.25532,766
127247.63.0.0/17247.63.0.1 to 247.63.127.254247.63.127.25532,766
128247.63.128.0/17247.63.128.1 to 247.63.255.254247.63.255.25532,766
129247.64.0.0/17247.64.0.1 to 247.64.127.254247.64.127.25532,766
130247.64.128.0/17247.64.128.1 to 247.64.255.254247.64.255.25532,766
131247.65.0.0/17247.65.0.1 to 247.65.127.254247.65.127.25532,766
132247.65.128.0/17247.65.128.1 to 247.65.255.254247.65.255.25532,766
133247.66.0.0/17247.66.0.1 to 247.66.127.254247.66.127.25532,766
134247.66.128.0/17247.66.128.1 to 247.66.255.254247.66.255.25532,766
135247.67.0.0/17247.67.0.1 to 247.67.127.254247.67.127.25532,766
136247.67.128.0/17247.67.128.1 to 247.67.255.254247.67.255.25532,766
137247.68.0.0/17247.68.0.1 to 247.68.127.254247.68.127.25532,766
138247.68.128.0/17247.68.128.1 to 247.68.255.254247.68.255.25532,766
139247.69.0.0/17247.69.0.1 to 247.69.127.254247.69.127.25532,766
140247.69.128.0/17247.69.128.1 to 247.69.255.254247.69.255.25532,766
141247.70.0.0/17247.70.0.1 to 247.70.127.254247.70.127.25532,766
142247.70.128.0/17247.70.128.1 to 247.70.255.254247.70.255.25532,766
143247.71.0.0/17247.71.0.1 to 247.71.127.254247.71.127.25532,766
144247.71.128.0/17247.71.128.1 to 247.71.255.254247.71.255.25532,766
145247.72.0.0/17247.72.0.1 to 247.72.127.254247.72.127.25532,766
146247.72.128.0/17247.72.128.1 to 247.72.255.254247.72.255.25532,766
147247.73.0.0/17247.73.0.1 to 247.73.127.254247.73.127.25532,766
148247.73.128.0/17247.73.128.1 to 247.73.255.254247.73.255.25532,766
149247.74.0.0/17247.74.0.1 to 247.74.127.254247.74.127.25532,766
150247.74.128.0/17247.74.128.1 to 247.74.255.254247.74.255.25532,766
151247.75.0.0/17247.75.0.1 to 247.75.127.254247.75.127.25532,766
152247.75.128.0/17247.75.128.1 to 247.75.255.254247.75.255.25532,766
153247.76.0.0/17247.76.0.1 to 247.76.127.254247.76.127.25532,766
154247.76.128.0/17247.76.128.1 to 247.76.255.254247.76.255.25532,766
155247.77.0.0/17247.77.0.1 to 247.77.127.254247.77.127.25532,766
156247.77.128.0/17247.77.128.1 to 247.77.255.254247.77.255.25532,766
157247.78.0.0/17247.78.0.1 to 247.78.127.254247.78.127.25532,766
158247.78.128.0/17247.78.128.1 to 247.78.255.254247.78.255.25532,766
159247.79.0.0/17247.79.0.1 to 247.79.127.254247.79.127.25532,766
160247.79.128.0/17247.79.128.1 to 247.79.255.254247.79.255.25532,766
161247.80.0.0/17247.80.0.1 to 247.80.127.254247.80.127.25532,766
162247.80.128.0/17247.80.128.1 to 247.80.255.254247.80.255.25532,766
163247.81.0.0/17247.81.0.1 to 247.81.127.254247.81.127.25532,766
164247.81.128.0/17247.81.128.1 to 247.81.255.254247.81.255.25532,766
165247.82.0.0/17247.82.0.1 to 247.82.127.254247.82.127.25532,766
166247.82.128.0/17247.82.128.1 to 247.82.255.254247.82.255.25532,766
167247.83.0.0/17247.83.0.1 to 247.83.127.254247.83.127.25532,766
168247.83.128.0/17247.83.128.1 to 247.83.255.254247.83.255.25532,766
169247.84.0.0/17247.84.0.1 to 247.84.127.254247.84.127.25532,766
170247.84.128.0/17247.84.128.1 to 247.84.255.254247.84.255.25532,766
171247.85.0.0/17247.85.0.1 to 247.85.127.254247.85.127.25532,766
172247.85.128.0/17247.85.128.1 to 247.85.255.254247.85.255.25532,766
173247.86.0.0/17247.86.0.1 to 247.86.127.254247.86.127.25532,766
174247.86.128.0/17247.86.128.1 to 247.86.255.254247.86.255.25532,766
175247.87.0.0/17247.87.0.1 to 247.87.127.254247.87.127.25532,766
176247.87.128.0/17247.87.128.1 to 247.87.255.254247.87.255.25532,766
177247.88.0.0/17247.88.0.1 to 247.88.127.254247.88.127.25532,766
178247.88.128.0/17247.88.128.1 to 247.88.255.254247.88.255.25532,766
179247.89.0.0/17247.89.0.1 to 247.89.127.254247.89.127.25532,766
180247.89.128.0/17247.89.128.1 to 247.89.255.254247.89.255.25532,766
181247.90.0.0/17247.90.0.1 to 247.90.127.254247.90.127.25532,766
182247.90.128.0/17247.90.128.1 to 247.90.255.254247.90.255.25532,766
183247.91.0.0/17247.91.0.1 to 247.91.127.254247.91.127.25532,766
184247.91.128.0/17247.91.128.1 to 247.91.255.254247.91.255.25532,766
185247.92.0.0/17247.92.0.1 to 247.92.127.254247.92.127.25532,766
186247.92.128.0/17247.92.128.1 to 247.92.255.254247.92.255.25532,766
187247.93.0.0/17247.93.0.1 to 247.93.127.254247.93.127.25532,766
188247.93.128.0/17247.93.128.1 to 247.93.255.254247.93.255.25532,766
189247.94.0.0/17247.94.0.1 to 247.94.127.254247.94.127.25532,766
190247.94.128.0/17247.94.128.1 to 247.94.255.254247.94.255.25532,766
191247.95.0.0/17247.95.0.1 to 247.95.127.254247.95.127.25532,766
192247.95.128.0/17247.95.128.1 to 247.95.255.254247.95.255.25532,766
193247.96.0.0/17247.96.0.1 to 247.96.127.254247.96.127.25532,766
194247.96.128.0/17247.96.128.1 to 247.96.255.254247.96.255.25532,766
195247.97.0.0/17247.97.0.1 to 247.97.127.254247.97.127.25532,766
196247.97.128.0/17247.97.128.1 to 247.97.255.254247.97.255.25532,766
197247.98.0.0/17247.98.0.1 to 247.98.127.254247.98.127.25532,766
198247.98.128.0/17247.98.128.1 to 247.98.255.254247.98.255.25532,766
199247.99.0.0/17247.99.0.1 to 247.99.127.254247.99.127.25532,766
200247.99.128.0/17247.99.128.1 to 247.99.255.254247.99.255.25532,766
201247.100.0.0/17247.100.0.1 to 247.100.127.254247.100.127.25532,766
202247.100.128.0/17247.100.128.1 to 247.100.255.254247.100.255.25532,766
203247.101.0.0/17247.101.0.1 to 247.101.127.254247.101.127.25532,766
204247.101.128.0/17247.101.128.1 to 247.101.255.254247.101.255.25532,766
205247.102.0.0/17247.102.0.1 to 247.102.127.254247.102.127.25532,766
206247.102.128.0/17247.102.128.1 to 247.102.255.254247.102.255.25532,766
207247.103.0.0/17247.103.0.1 to 247.103.127.254247.103.127.25532,766
208247.103.128.0/17247.103.128.1 to 247.103.255.254247.103.255.25532,766
209247.104.0.0/17247.104.0.1 to 247.104.127.254247.104.127.25532,766
210247.104.128.0/17247.104.128.1 to 247.104.255.254247.104.255.25532,766
211247.105.0.0/17247.105.0.1 to 247.105.127.254247.105.127.25532,766
212247.105.128.0/17247.105.128.1 to 247.105.255.254247.105.255.25532,766
213247.106.0.0/17247.106.0.1 to 247.106.127.254247.106.127.25532,766
214247.106.128.0/17247.106.128.1 to 247.106.255.254247.106.255.25532,766
215247.107.0.0/17247.107.0.1 to 247.107.127.254247.107.127.25532,766
216247.107.128.0/17247.107.128.1 to 247.107.255.254247.107.255.25532,766
217247.108.0.0/17247.108.0.1 to 247.108.127.254247.108.127.25532,766
218247.108.128.0/17247.108.128.1 to 247.108.255.254247.108.255.25532,766
219247.109.0.0/17247.109.0.1 to 247.109.127.254247.109.127.25532,766
220247.109.128.0/17247.109.128.1 to 247.109.255.254247.109.255.25532,766
221247.110.0.0/17247.110.0.1 to 247.110.127.254247.110.127.25532,766
222247.110.128.0/17247.110.128.1 to 247.110.255.254247.110.255.25532,766
223247.111.0.0/17247.111.0.1 to 247.111.127.254247.111.127.25532,766
224247.111.128.0/17247.111.128.1 to 247.111.255.254247.111.255.25532,766
225247.112.0.0/17247.112.0.1 to 247.112.127.254247.112.127.25532,766
226247.112.128.0/17247.112.128.1 to 247.112.255.254247.112.255.25532,766
227247.113.0.0/17247.113.0.1 to 247.113.127.254247.113.127.25532,766
228247.113.128.0/17247.113.128.1 to 247.113.255.254247.113.255.25532,766
229247.114.0.0/17247.114.0.1 to 247.114.127.254247.114.127.25532,766
230247.114.128.0/17247.114.128.1 to 247.114.255.254247.114.255.25532,766
231247.115.0.0/17247.115.0.1 to 247.115.127.254247.115.127.25532,766
232247.115.128.0/17247.115.128.1 to 247.115.255.254247.115.255.25532,766
233247.116.0.0/17247.116.0.1 to 247.116.127.254247.116.127.25532,766
234247.116.128.0/17247.116.128.1 to 247.116.255.254247.116.255.25532,766
235247.117.0.0/17247.117.0.1 to 247.117.127.254247.117.127.25532,766
236247.117.128.0/17247.117.128.1 to 247.117.255.254247.117.255.25532,766
237247.118.0.0/17247.118.0.1 to 247.118.127.254247.118.127.25532,766
238247.118.128.0/17247.118.128.1 to 247.118.255.254247.118.255.25532,766
239247.119.0.0/17247.119.0.1 to 247.119.127.254247.119.127.25532,766
240247.119.128.0/17247.119.128.1 to 247.119.255.254247.119.255.25532,766
241247.120.0.0/17247.120.0.1 to 247.120.127.254247.120.127.25532,766
242247.120.128.0/17247.120.128.1 to 247.120.255.254247.120.255.25532,766
243247.121.0.0/17247.121.0.1 to 247.121.127.254247.121.127.25532,766
244247.121.128.0/17247.121.128.1 to 247.121.255.254247.121.255.25532,766
245247.122.0.0/17247.122.0.1 to 247.122.127.254247.122.127.25532,766
246247.122.128.0/17247.122.128.1 to 247.122.255.254247.122.255.25532,766
247247.123.0.0/17247.123.0.1 to 247.123.127.254247.123.127.25532,766
248247.123.128.0/17247.123.128.1 to 247.123.255.254247.123.255.25532,766
249247.124.0.0/17247.124.0.1 to 247.124.127.254247.124.127.25532,766
250247.124.128.0/17247.124.128.1 to 247.124.255.254247.124.255.25532,766
251247.125.0.0/17247.125.0.1 to 247.125.127.254247.125.127.25532,766
252247.125.128.0/17247.125.128.1 to 247.125.255.254247.125.255.25532,766
253247.126.0.0/17247.126.0.1 to 247.126.127.254247.126.127.25532,766
254247.126.128.0/17247.126.128.1 to 247.126.255.254247.126.255.25532,766
255247.127.0.0/17247.127.0.1 to 247.127.127.254247.127.127.25532,766
256247.127.128.0/17247.127.128.1 to 247.127.255.254247.127.255.25532,766

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.