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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.

Network221.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
221.0.0.0
Broadcast address
221.255.255.255
First usable
221.0.0.1
Last usable
221.255.255.254
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
C (default /24)
As numbers
Hex DD000000 · Integer 3707764736 to 3724541951
Reverse DNS zone
221.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011101..00000000.00000000.00000000221.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11011101..00000000.00000000.00000000221.0.0.0
Broadcast11011101..11111111.11111111.11111111221.255.255.255
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)

221.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1221.0.0.0/17221.0.0.1 to 221.0.127.254221.0.127.25532,766
2221.0.128.0/17221.0.128.1 to 221.0.255.254221.0.255.25532,766
3221.1.0.0/17221.1.0.1 to 221.1.127.254221.1.127.25532,766
4221.1.128.0/17221.1.128.1 to 221.1.255.254221.1.255.25532,766
5221.2.0.0/17221.2.0.1 to 221.2.127.254221.2.127.25532,766
6221.2.128.0/17221.2.128.1 to 221.2.255.254221.2.255.25532,766
7221.3.0.0/17221.3.0.1 to 221.3.127.254221.3.127.25532,766
8221.3.128.0/17221.3.128.1 to 221.3.255.254221.3.255.25532,766
9221.4.0.0/17221.4.0.1 to 221.4.127.254221.4.127.25532,766
10221.4.128.0/17221.4.128.1 to 221.4.255.254221.4.255.25532,766
11221.5.0.0/17221.5.0.1 to 221.5.127.254221.5.127.25532,766
12221.5.128.0/17221.5.128.1 to 221.5.255.254221.5.255.25532,766
13221.6.0.0/17221.6.0.1 to 221.6.127.254221.6.127.25532,766
14221.6.128.0/17221.6.128.1 to 221.6.255.254221.6.255.25532,766
15221.7.0.0/17221.7.0.1 to 221.7.127.254221.7.127.25532,766
16221.7.128.0/17221.7.128.1 to 221.7.255.254221.7.255.25532,766
17221.8.0.0/17221.8.0.1 to 221.8.127.254221.8.127.25532,766
18221.8.128.0/17221.8.128.1 to 221.8.255.254221.8.255.25532,766
19221.9.0.0/17221.9.0.1 to 221.9.127.254221.9.127.25532,766
20221.9.128.0/17221.9.128.1 to 221.9.255.254221.9.255.25532,766
21221.10.0.0/17221.10.0.1 to 221.10.127.254221.10.127.25532,766
22221.10.128.0/17221.10.128.1 to 221.10.255.254221.10.255.25532,766
23221.11.0.0/17221.11.0.1 to 221.11.127.254221.11.127.25532,766
24221.11.128.0/17221.11.128.1 to 221.11.255.254221.11.255.25532,766
25221.12.0.0/17221.12.0.1 to 221.12.127.254221.12.127.25532,766
26221.12.128.0/17221.12.128.1 to 221.12.255.254221.12.255.25532,766
27221.13.0.0/17221.13.0.1 to 221.13.127.254221.13.127.25532,766
28221.13.128.0/17221.13.128.1 to 221.13.255.254221.13.255.25532,766
29221.14.0.0/17221.14.0.1 to 221.14.127.254221.14.127.25532,766
30221.14.128.0/17221.14.128.1 to 221.14.255.254221.14.255.25532,766
31221.15.0.0/17221.15.0.1 to 221.15.127.254221.15.127.25532,766
32221.15.128.0/17221.15.128.1 to 221.15.255.254221.15.255.25532,766
33221.16.0.0/17221.16.0.1 to 221.16.127.254221.16.127.25532,766
34221.16.128.0/17221.16.128.1 to 221.16.255.254221.16.255.25532,766
35221.17.0.0/17221.17.0.1 to 221.17.127.254221.17.127.25532,766
36221.17.128.0/17221.17.128.1 to 221.17.255.254221.17.255.25532,766
37221.18.0.0/17221.18.0.1 to 221.18.127.254221.18.127.25532,766
38221.18.128.0/17221.18.128.1 to 221.18.255.254221.18.255.25532,766
39221.19.0.0/17221.19.0.1 to 221.19.127.254221.19.127.25532,766
40221.19.128.0/17221.19.128.1 to 221.19.255.254221.19.255.25532,766
41221.20.0.0/17221.20.0.1 to 221.20.127.254221.20.127.25532,766
42221.20.128.0/17221.20.128.1 to 221.20.255.254221.20.255.25532,766
43221.21.0.0/17221.21.0.1 to 221.21.127.254221.21.127.25532,766
44221.21.128.0/17221.21.128.1 to 221.21.255.254221.21.255.25532,766
45221.22.0.0/17221.22.0.1 to 221.22.127.254221.22.127.25532,766
46221.22.128.0/17221.22.128.1 to 221.22.255.254221.22.255.25532,766
47221.23.0.0/17221.23.0.1 to 221.23.127.254221.23.127.25532,766
48221.23.128.0/17221.23.128.1 to 221.23.255.254221.23.255.25532,766
49221.24.0.0/17221.24.0.1 to 221.24.127.254221.24.127.25532,766
50221.24.128.0/17221.24.128.1 to 221.24.255.254221.24.255.25532,766
51221.25.0.0/17221.25.0.1 to 221.25.127.254221.25.127.25532,766
52221.25.128.0/17221.25.128.1 to 221.25.255.254221.25.255.25532,766
53221.26.0.0/17221.26.0.1 to 221.26.127.254221.26.127.25532,766
54221.26.128.0/17221.26.128.1 to 221.26.255.254221.26.255.25532,766
55221.27.0.0/17221.27.0.1 to 221.27.127.254221.27.127.25532,766
56221.27.128.0/17221.27.128.1 to 221.27.255.254221.27.255.25532,766
57221.28.0.0/17221.28.0.1 to 221.28.127.254221.28.127.25532,766
58221.28.128.0/17221.28.128.1 to 221.28.255.254221.28.255.25532,766
59221.29.0.0/17221.29.0.1 to 221.29.127.254221.29.127.25532,766
60221.29.128.0/17221.29.128.1 to 221.29.255.254221.29.255.25532,766
61221.30.0.0/17221.30.0.1 to 221.30.127.254221.30.127.25532,766
62221.30.128.0/17221.30.128.1 to 221.30.255.254221.30.255.25532,766
63221.31.0.0/17221.31.0.1 to 221.31.127.254221.31.127.25532,766
64221.31.128.0/17221.31.128.1 to 221.31.255.254221.31.255.25532,766
65221.32.0.0/17221.32.0.1 to 221.32.127.254221.32.127.25532,766
66221.32.128.0/17221.32.128.1 to 221.32.255.254221.32.255.25532,766
67221.33.0.0/17221.33.0.1 to 221.33.127.254221.33.127.25532,766
68221.33.128.0/17221.33.128.1 to 221.33.255.254221.33.255.25532,766
69221.34.0.0/17221.34.0.1 to 221.34.127.254221.34.127.25532,766
70221.34.128.0/17221.34.128.1 to 221.34.255.254221.34.255.25532,766
71221.35.0.0/17221.35.0.1 to 221.35.127.254221.35.127.25532,766
72221.35.128.0/17221.35.128.1 to 221.35.255.254221.35.255.25532,766
73221.36.0.0/17221.36.0.1 to 221.36.127.254221.36.127.25532,766
74221.36.128.0/17221.36.128.1 to 221.36.255.254221.36.255.25532,766
75221.37.0.0/17221.37.0.1 to 221.37.127.254221.37.127.25532,766
76221.37.128.0/17221.37.128.1 to 221.37.255.254221.37.255.25532,766
77221.38.0.0/17221.38.0.1 to 221.38.127.254221.38.127.25532,766
78221.38.128.0/17221.38.128.1 to 221.38.255.254221.38.255.25532,766
79221.39.0.0/17221.39.0.1 to 221.39.127.254221.39.127.25532,766
80221.39.128.0/17221.39.128.1 to 221.39.255.254221.39.255.25532,766
81221.40.0.0/17221.40.0.1 to 221.40.127.254221.40.127.25532,766
82221.40.128.0/17221.40.128.1 to 221.40.255.254221.40.255.25532,766
83221.41.0.0/17221.41.0.1 to 221.41.127.254221.41.127.25532,766
84221.41.128.0/17221.41.128.1 to 221.41.255.254221.41.255.25532,766
85221.42.0.0/17221.42.0.1 to 221.42.127.254221.42.127.25532,766
86221.42.128.0/17221.42.128.1 to 221.42.255.254221.42.255.25532,766
87221.43.0.0/17221.43.0.1 to 221.43.127.254221.43.127.25532,766
88221.43.128.0/17221.43.128.1 to 221.43.255.254221.43.255.25532,766
89221.44.0.0/17221.44.0.1 to 221.44.127.254221.44.127.25532,766
90221.44.128.0/17221.44.128.1 to 221.44.255.254221.44.255.25532,766
91221.45.0.0/17221.45.0.1 to 221.45.127.254221.45.127.25532,766
92221.45.128.0/17221.45.128.1 to 221.45.255.254221.45.255.25532,766
93221.46.0.0/17221.46.0.1 to 221.46.127.254221.46.127.25532,766
94221.46.128.0/17221.46.128.1 to 221.46.255.254221.46.255.25532,766
95221.47.0.0/17221.47.0.1 to 221.47.127.254221.47.127.25532,766
96221.47.128.0/17221.47.128.1 to 221.47.255.254221.47.255.25532,766
97221.48.0.0/17221.48.0.1 to 221.48.127.254221.48.127.25532,766
98221.48.128.0/17221.48.128.1 to 221.48.255.254221.48.255.25532,766
99221.49.0.0/17221.49.0.1 to 221.49.127.254221.49.127.25532,766
100221.49.128.0/17221.49.128.1 to 221.49.255.254221.49.255.25532,766
101221.50.0.0/17221.50.0.1 to 221.50.127.254221.50.127.25532,766
102221.50.128.0/17221.50.128.1 to 221.50.255.254221.50.255.25532,766
103221.51.0.0/17221.51.0.1 to 221.51.127.254221.51.127.25532,766
104221.51.128.0/17221.51.128.1 to 221.51.255.254221.51.255.25532,766
105221.52.0.0/17221.52.0.1 to 221.52.127.254221.52.127.25532,766
106221.52.128.0/17221.52.128.1 to 221.52.255.254221.52.255.25532,766
107221.53.0.0/17221.53.0.1 to 221.53.127.254221.53.127.25532,766
108221.53.128.0/17221.53.128.1 to 221.53.255.254221.53.255.25532,766
109221.54.0.0/17221.54.0.1 to 221.54.127.254221.54.127.25532,766
110221.54.128.0/17221.54.128.1 to 221.54.255.254221.54.255.25532,766
111221.55.0.0/17221.55.0.1 to 221.55.127.254221.55.127.25532,766
112221.55.128.0/17221.55.128.1 to 221.55.255.254221.55.255.25532,766
113221.56.0.0/17221.56.0.1 to 221.56.127.254221.56.127.25532,766
114221.56.128.0/17221.56.128.1 to 221.56.255.254221.56.255.25532,766
115221.57.0.0/17221.57.0.1 to 221.57.127.254221.57.127.25532,766
116221.57.128.0/17221.57.128.1 to 221.57.255.254221.57.255.25532,766
117221.58.0.0/17221.58.0.1 to 221.58.127.254221.58.127.25532,766
118221.58.128.0/17221.58.128.1 to 221.58.255.254221.58.255.25532,766
119221.59.0.0/17221.59.0.1 to 221.59.127.254221.59.127.25532,766
120221.59.128.0/17221.59.128.1 to 221.59.255.254221.59.255.25532,766
121221.60.0.0/17221.60.0.1 to 221.60.127.254221.60.127.25532,766
122221.60.128.0/17221.60.128.1 to 221.60.255.254221.60.255.25532,766
123221.61.0.0/17221.61.0.1 to 221.61.127.254221.61.127.25532,766
124221.61.128.0/17221.61.128.1 to 221.61.255.254221.61.255.25532,766
125221.62.0.0/17221.62.0.1 to 221.62.127.254221.62.127.25532,766
126221.62.128.0/17221.62.128.1 to 221.62.255.254221.62.255.25532,766
127221.63.0.0/17221.63.0.1 to 221.63.127.254221.63.127.25532,766
128221.63.128.0/17221.63.128.1 to 221.63.255.254221.63.255.25532,766
129221.64.0.0/17221.64.0.1 to 221.64.127.254221.64.127.25532,766
130221.64.128.0/17221.64.128.1 to 221.64.255.254221.64.255.25532,766
131221.65.0.0/17221.65.0.1 to 221.65.127.254221.65.127.25532,766
132221.65.128.0/17221.65.128.1 to 221.65.255.254221.65.255.25532,766
133221.66.0.0/17221.66.0.1 to 221.66.127.254221.66.127.25532,766
134221.66.128.0/17221.66.128.1 to 221.66.255.254221.66.255.25532,766
135221.67.0.0/17221.67.0.1 to 221.67.127.254221.67.127.25532,766
136221.67.128.0/17221.67.128.1 to 221.67.255.254221.67.255.25532,766
137221.68.0.0/17221.68.0.1 to 221.68.127.254221.68.127.25532,766
138221.68.128.0/17221.68.128.1 to 221.68.255.254221.68.255.25532,766
139221.69.0.0/17221.69.0.1 to 221.69.127.254221.69.127.25532,766
140221.69.128.0/17221.69.128.1 to 221.69.255.254221.69.255.25532,766
141221.70.0.0/17221.70.0.1 to 221.70.127.254221.70.127.25532,766
142221.70.128.0/17221.70.128.1 to 221.70.255.254221.70.255.25532,766
143221.71.0.0/17221.71.0.1 to 221.71.127.254221.71.127.25532,766
144221.71.128.0/17221.71.128.1 to 221.71.255.254221.71.255.25532,766
145221.72.0.0/17221.72.0.1 to 221.72.127.254221.72.127.25532,766
146221.72.128.0/17221.72.128.1 to 221.72.255.254221.72.255.25532,766
147221.73.0.0/17221.73.0.1 to 221.73.127.254221.73.127.25532,766
148221.73.128.0/17221.73.128.1 to 221.73.255.254221.73.255.25532,766
149221.74.0.0/17221.74.0.1 to 221.74.127.254221.74.127.25532,766
150221.74.128.0/17221.74.128.1 to 221.74.255.254221.74.255.25532,766
151221.75.0.0/17221.75.0.1 to 221.75.127.254221.75.127.25532,766
152221.75.128.0/17221.75.128.1 to 221.75.255.254221.75.255.25532,766
153221.76.0.0/17221.76.0.1 to 221.76.127.254221.76.127.25532,766
154221.76.128.0/17221.76.128.1 to 221.76.255.254221.76.255.25532,766
155221.77.0.0/17221.77.0.1 to 221.77.127.254221.77.127.25532,766
156221.77.128.0/17221.77.128.1 to 221.77.255.254221.77.255.25532,766
157221.78.0.0/17221.78.0.1 to 221.78.127.254221.78.127.25532,766
158221.78.128.0/17221.78.128.1 to 221.78.255.254221.78.255.25532,766
159221.79.0.0/17221.79.0.1 to 221.79.127.254221.79.127.25532,766
160221.79.128.0/17221.79.128.1 to 221.79.255.254221.79.255.25532,766
161221.80.0.0/17221.80.0.1 to 221.80.127.254221.80.127.25532,766
162221.80.128.0/17221.80.128.1 to 221.80.255.254221.80.255.25532,766
163221.81.0.0/17221.81.0.1 to 221.81.127.254221.81.127.25532,766
164221.81.128.0/17221.81.128.1 to 221.81.255.254221.81.255.25532,766
165221.82.0.0/17221.82.0.1 to 221.82.127.254221.82.127.25532,766
166221.82.128.0/17221.82.128.1 to 221.82.255.254221.82.255.25532,766
167221.83.0.0/17221.83.0.1 to 221.83.127.254221.83.127.25532,766
168221.83.128.0/17221.83.128.1 to 221.83.255.254221.83.255.25532,766
169221.84.0.0/17221.84.0.1 to 221.84.127.254221.84.127.25532,766
170221.84.128.0/17221.84.128.1 to 221.84.255.254221.84.255.25532,766
171221.85.0.0/17221.85.0.1 to 221.85.127.254221.85.127.25532,766
172221.85.128.0/17221.85.128.1 to 221.85.255.254221.85.255.25532,766
173221.86.0.0/17221.86.0.1 to 221.86.127.254221.86.127.25532,766
174221.86.128.0/17221.86.128.1 to 221.86.255.254221.86.255.25532,766
175221.87.0.0/17221.87.0.1 to 221.87.127.254221.87.127.25532,766
176221.87.128.0/17221.87.128.1 to 221.87.255.254221.87.255.25532,766
177221.88.0.0/17221.88.0.1 to 221.88.127.254221.88.127.25532,766
178221.88.128.0/17221.88.128.1 to 221.88.255.254221.88.255.25532,766
179221.89.0.0/17221.89.0.1 to 221.89.127.254221.89.127.25532,766
180221.89.128.0/17221.89.128.1 to 221.89.255.254221.89.255.25532,766
181221.90.0.0/17221.90.0.1 to 221.90.127.254221.90.127.25532,766
182221.90.128.0/17221.90.128.1 to 221.90.255.254221.90.255.25532,766
183221.91.0.0/17221.91.0.1 to 221.91.127.254221.91.127.25532,766
184221.91.128.0/17221.91.128.1 to 221.91.255.254221.91.255.25532,766
185221.92.0.0/17221.92.0.1 to 221.92.127.254221.92.127.25532,766
186221.92.128.0/17221.92.128.1 to 221.92.255.254221.92.255.25532,766
187221.93.0.0/17221.93.0.1 to 221.93.127.254221.93.127.25532,766
188221.93.128.0/17221.93.128.1 to 221.93.255.254221.93.255.25532,766
189221.94.0.0/17221.94.0.1 to 221.94.127.254221.94.127.25532,766
190221.94.128.0/17221.94.128.1 to 221.94.255.254221.94.255.25532,766
191221.95.0.0/17221.95.0.1 to 221.95.127.254221.95.127.25532,766
192221.95.128.0/17221.95.128.1 to 221.95.255.254221.95.255.25532,766
193221.96.0.0/17221.96.0.1 to 221.96.127.254221.96.127.25532,766
194221.96.128.0/17221.96.128.1 to 221.96.255.254221.96.255.25532,766
195221.97.0.0/17221.97.0.1 to 221.97.127.254221.97.127.25532,766
196221.97.128.0/17221.97.128.1 to 221.97.255.254221.97.255.25532,766
197221.98.0.0/17221.98.0.1 to 221.98.127.254221.98.127.25532,766
198221.98.128.0/17221.98.128.1 to 221.98.255.254221.98.255.25532,766
199221.99.0.0/17221.99.0.1 to 221.99.127.254221.99.127.25532,766
200221.99.128.0/17221.99.128.1 to 221.99.255.254221.99.255.25532,766
201221.100.0.0/17221.100.0.1 to 221.100.127.254221.100.127.25532,766
202221.100.128.0/17221.100.128.1 to 221.100.255.254221.100.255.25532,766
203221.101.0.0/17221.101.0.1 to 221.101.127.254221.101.127.25532,766
204221.101.128.0/17221.101.128.1 to 221.101.255.254221.101.255.25532,766
205221.102.0.0/17221.102.0.1 to 221.102.127.254221.102.127.25532,766
206221.102.128.0/17221.102.128.1 to 221.102.255.254221.102.255.25532,766
207221.103.0.0/17221.103.0.1 to 221.103.127.254221.103.127.25532,766
208221.103.128.0/17221.103.128.1 to 221.103.255.254221.103.255.25532,766
209221.104.0.0/17221.104.0.1 to 221.104.127.254221.104.127.25532,766
210221.104.128.0/17221.104.128.1 to 221.104.255.254221.104.255.25532,766
211221.105.0.0/17221.105.0.1 to 221.105.127.254221.105.127.25532,766
212221.105.128.0/17221.105.128.1 to 221.105.255.254221.105.255.25532,766
213221.106.0.0/17221.106.0.1 to 221.106.127.254221.106.127.25532,766
214221.106.128.0/17221.106.128.1 to 221.106.255.254221.106.255.25532,766
215221.107.0.0/17221.107.0.1 to 221.107.127.254221.107.127.25532,766
216221.107.128.0/17221.107.128.1 to 221.107.255.254221.107.255.25532,766
217221.108.0.0/17221.108.0.1 to 221.108.127.254221.108.127.25532,766
218221.108.128.0/17221.108.128.1 to 221.108.255.254221.108.255.25532,766
219221.109.0.0/17221.109.0.1 to 221.109.127.254221.109.127.25532,766
220221.109.128.0/17221.109.128.1 to 221.109.255.254221.109.255.25532,766
221221.110.0.0/17221.110.0.1 to 221.110.127.254221.110.127.25532,766
222221.110.128.0/17221.110.128.1 to 221.110.255.254221.110.255.25532,766
223221.111.0.0/17221.111.0.1 to 221.111.127.254221.111.127.25532,766
224221.111.128.0/17221.111.128.1 to 221.111.255.254221.111.255.25532,766
225221.112.0.0/17221.112.0.1 to 221.112.127.254221.112.127.25532,766
226221.112.128.0/17221.112.128.1 to 221.112.255.254221.112.255.25532,766
227221.113.0.0/17221.113.0.1 to 221.113.127.254221.113.127.25532,766
228221.113.128.0/17221.113.128.1 to 221.113.255.254221.113.255.25532,766
229221.114.0.0/17221.114.0.1 to 221.114.127.254221.114.127.25532,766
230221.114.128.0/17221.114.128.1 to 221.114.255.254221.114.255.25532,766
231221.115.0.0/17221.115.0.1 to 221.115.127.254221.115.127.25532,766
232221.115.128.0/17221.115.128.1 to 221.115.255.254221.115.255.25532,766
233221.116.0.0/17221.116.0.1 to 221.116.127.254221.116.127.25532,766
234221.116.128.0/17221.116.128.1 to 221.116.255.254221.116.255.25532,766
235221.117.0.0/17221.117.0.1 to 221.117.127.254221.117.127.25532,766
236221.117.128.0/17221.117.128.1 to 221.117.255.254221.117.255.25532,766
237221.118.0.0/17221.118.0.1 to 221.118.127.254221.118.127.25532,766
238221.118.128.0/17221.118.128.1 to 221.118.255.254221.118.255.25532,766
239221.119.0.0/17221.119.0.1 to 221.119.127.254221.119.127.25532,766
240221.119.128.0/17221.119.128.1 to 221.119.255.254221.119.255.25532,766
241221.120.0.0/17221.120.0.1 to 221.120.127.254221.120.127.25532,766
242221.120.128.0/17221.120.128.1 to 221.120.255.254221.120.255.25532,766
243221.121.0.0/17221.121.0.1 to 221.121.127.254221.121.127.25532,766
244221.121.128.0/17221.121.128.1 to 221.121.255.254221.121.255.25532,766
245221.122.0.0/17221.122.0.1 to 221.122.127.254221.122.127.25532,766
246221.122.128.0/17221.122.128.1 to 221.122.255.254221.122.255.25532,766
247221.123.0.0/17221.123.0.1 to 221.123.127.254221.123.127.25532,766
248221.123.128.0/17221.123.128.1 to 221.123.255.254221.123.255.25532,766
249221.124.0.0/17221.124.0.1 to 221.124.127.254221.124.127.25532,766
250221.124.128.0/17221.124.128.1 to 221.124.255.254221.124.255.25532,766
251221.125.0.0/17221.125.0.1 to 221.125.127.254221.125.127.25532,766
252221.125.128.0/17221.125.128.1 to 221.125.255.254221.125.255.25532,766
253221.126.0.0/17221.126.0.1 to 221.126.127.254221.126.127.25532,766
254221.126.128.0/17221.126.128.1 to 221.126.255.254221.126.255.25532,766
255221.127.0.0/17221.127.0.1 to 221.127.127.254221.127.127.25532,766
256221.127.128.0/17221.127.128.1 to 221.127.255.254221.127.255.25532,766

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.