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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.

Network191.44.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
191.44.0.0
Broadcast address
191.44.127.255
First usable
191.44.0.1
Last usable
191.44.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex BF2C0000 · Integer 3207331840 to 3207364607
Reverse DNS zones
0.44.191.in-addr.arpa
1.44.191.in-addr.arpa
2.44.191.in-addr.arpa
3.44.191.in-addr.arpa
4.44.191.in-addr.arpa
5.44.191.in-addr.arpa
6.44.191.in-addr.arpa
7.44.191.in-addr.arpa
8.44.191.in-addr.arpa
9.44.191.in-addr.arpa
10.44.191.in-addr.arpa
11.44.191.in-addr.arpa
12.44.191.in-addr.arpa
13.44.191.in-addr.arpa
14.44.191.in-addr.arpa
15.44.191.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111111.00101100.00000000.00000000191.44.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10111111.00101100.00000000.00000000191.44.0.0
Broadcast10111111.00101100.01111111.11111111191.44.127.255
Split into smaller subnets/25
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

191.44.0.0/17 makes 256 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1191.44.0.0/25191.44.0.1 to 191.44.0.126191.44.0.127126
2191.44.0.128/25191.44.0.129 to 191.44.0.254191.44.0.255126
3191.44.1.0/25191.44.1.1 to 191.44.1.126191.44.1.127126
4191.44.1.128/25191.44.1.129 to 191.44.1.254191.44.1.255126
5191.44.2.0/25191.44.2.1 to 191.44.2.126191.44.2.127126
6191.44.2.128/25191.44.2.129 to 191.44.2.254191.44.2.255126
7191.44.3.0/25191.44.3.1 to 191.44.3.126191.44.3.127126
8191.44.3.128/25191.44.3.129 to 191.44.3.254191.44.3.255126
9191.44.4.0/25191.44.4.1 to 191.44.4.126191.44.4.127126
10191.44.4.128/25191.44.4.129 to 191.44.4.254191.44.4.255126
11191.44.5.0/25191.44.5.1 to 191.44.5.126191.44.5.127126
12191.44.5.128/25191.44.5.129 to 191.44.5.254191.44.5.255126
13191.44.6.0/25191.44.6.1 to 191.44.6.126191.44.6.127126
14191.44.6.128/25191.44.6.129 to 191.44.6.254191.44.6.255126
15191.44.7.0/25191.44.7.1 to 191.44.7.126191.44.7.127126
16191.44.7.128/25191.44.7.129 to 191.44.7.254191.44.7.255126
17191.44.8.0/25191.44.8.1 to 191.44.8.126191.44.8.127126
18191.44.8.128/25191.44.8.129 to 191.44.8.254191.44.8.255126
19191.44.9.0/25191.44.9.1 to 191.44.9.126191.44.9.127126
20191.44.9.128/25191.44.9.129 to 191.44.9.254191.44.9.255126
21191.44.10.0/25191.44.10.1 to 191.44.10.126191.44.10.127126
22191.44.10.128/25191.44.10.129 to 191.44.10.254191.44.10.255126
23191.44.11.0/25191.44.11.1 to 191.44.11.126191.44.11.127126
24191.44.11.128/25191.44.11.129 to 191.44.11.254191.44.11.255126
25191.44.12.0/25191.44.12.1 to 191.44.12.126191.44.12.127126
26191.44.12.128/25191.44.12.129 to 191.44.12.254191.44.12.255126
27191.44.13.0/25191.44.13.1 to 191.44.13.126191.44.13.127126
28191.44.13.128/25191.44.13.129 to 191.44.13.254191.44.13.255126
29191.44.14.0/25191.44.14.1 to 191.44.14.126191.44.14.127126
30191.44.14.128/25191.44.14.129 to 191.44.14.254191.44.14.255126
31191.44.15.0/25191.44.15.1 to 191.44.15.126191.44.15.127126
32191.44.15.128/25191.44.15.129 to 191.44.15.254191.44.15.255126
33191.44.16.0/25191.44.16.1 to 191.44.16.126191.44.16.127126
34191.44.16.128/25191.44.16.129 to 191.44.16.254191.44.16.255126
35191.44.17.0/25191.44.17.1 to 191.44.17.126191.44.17.127126
36191.44.17.128/25191.44.17.129 to 191.44.17.254191.44.17.255126
37191.44.18.0/25191.44.18.1 to 191.44.18.126191.44.18.127126
38191.44.18.128/25191.44.18.129 to 191.44.18.254191.44.18.255126
39191.44.19.0/25191.44.19.1 to 191.44.19.126191.44.19.127126
40191.44.19.128/25191.44.19.129 to 191.44.19.254191.44.19.255126
41191.44.20.0/25191.44.20.1 to 191.44.20.126191.44.20.127126
42191.44.20.128/25191.44.20.129 to 191.44.20.254191.44.20.255126
43191.44.21.0/25191.44.21.1 to 191.44.21.126191.44.21.127126
44191.44.21.128/25191.44.21.129 to 191.44.21.254191.44.21.255126
45191.44.22.0/25191.44.22.1 to 191.44.22.126191.44.22.127126
46191.44.22.128/25191.44.22.129 to 191.44.22.254191.44.22.255126
47191.44.23.0/25191.44.23.1 to 191.44.23.126191.44.23.127126
48191.44.23.128/25191.44.23.129 to 191.44.23.254191.44.23.255126
49191.44.24.0/25191.44.24.1 to 191.44.24.126191.44.24.127126
50191.44.24.128/25191.44.24.129 to 191.44.24.254191.44.24.255126
51191.44.25.0/25191.44.25.1 to 191.44.25.126191.44.25.127126
52191.44.25.128/25191.44.25.129 to 191.44.25.254191.44.25.255126
53191.44.26.0/25191.44.26.1 to 191.44.26.126191.44.26.127126
54191.44.26.128/25191.44.26.129 to 191.44.26.254191.44.26.255126
55191.44.27.0/25191.44.27.1 to 191.44.27.126191.44.27.127126
56191.44.27.128/25191.44.27.129 to 191.44.27.254191.44.27.255126
57191.44.28.0/25191.44.28.1 to 191.44.28.126191.44.28.127126
58191.44.28.128/25191.44.28.129 to 191.44.28.254191.44.28.255126
59191.44.29.0/25191.44.29.1 to 191.44.29.126191.44.29.127126
60191.44.29.128/25191.44.29.129 to 191.44.29.254191.44.29.255126
61191.44.30.0/25191.44.30.1 to 191.44.30.126191.44.30.127126
62191.44.30.128/25191.44.30.129 to 191.44.30.254191.44.30.255126
63191.44.31.0/25191.44.31.1 to 191.44.31.126191.44.31.127126
64191.44.31.128/25191.44.31.129 to 191.44.31.254191.44.31.255126
65191.44.32.0/25191.44.32.1 to 191.44.32.126191.44.32.127126
66191.44.32.128/25191.44.32.129 to 191.44.32.254191.44.32.255126
67191.44.33.0/25191.44.33.1 to 191.44.33.126191.44.33.127126
68191.44.33.128/25191.44.33.129 to 191.44.33.254191.44.33.255126
69191.44.34.0/25191.44.34.1 to 191.44.34.126191.44.34.127126
70191.44.34.128/25191.44.34.129 to 191.44.34.254191.44.34.255126
71191.44.35.0/25191.44.35.1 to 191.44.35.126191.44.35.127126
72191.44.35.128/25191.44.35.129 to 191.44.35.254191.44.35.255126
73191.44.36.0/25191.44.36.1 to 191.44.36.126191.44.36.127126
74191.44.36.128/25191.44.36.129 to 191.44.36.254191.44.36.255126
75191.44.37.0/25191.44.37.1 to 191.44.37.126191.44.37.127126
76191.44.37.128/25191.44.37.129 to 191.44.37.254191.44.37.255126
77191.44.38.0/25191.44.38.1 to 191.44.38.126191.44.38.127126
78191.44.38.128/25191.44.38.129 to 191.44.38.254191.44.38.255126
79191.44.39.0/25191.44.39.1 to 191.44.39.126191.44.39.127126
80191.44.39.128/25191.44.39.129 to 191.44.39.254191.44.39.255126
81191.44.40.0/25191.44.40.1 to 191.44.40.126191.44.40.127126
82191.44.40.128/25191.44.40.129 to 191.44.40.254191.44.40.255126
83191.44.41.0/25191.44.41.1 to 191.44.41.126191.44.41.127126
84191.44.41.128/25191.44.41.129 to 191.44.41.254191.44.41.255126
85191.44.42.0/25191.44.42.1 to 191.44.42.126191.44.42.127126
86191.44.42.128/25191.44.42.129 to 191.44.42.254191.44.42.255126
87191.44.43.0/25191.44.43.1 to 191.44.43.126191.44.43.127126
88191.44.43.128/25191.44.43.129 to 191.44.43.254191.44.43.255126
89191.44.44.0/25191.44.44.1 to 191.44.44.126191.44.44.127126
90191.44.44.128/25191.44.44.129 to 191.44.44.254191.44.44.255126
91191.44.45.0/25191.44.45.1 to 191.44.45.126191.44.45.127126
92191.44.45.128/25191.44.45.129 to 191.44.45.254191.44.45.255126
93191.44.46.0/25191.44.46.1 to 191.44.46.126191.44.46.127126
94191.44.46.128/25191.44.46.129 to 191.44.46.254191.44.46.255126
95191.44.47.0/25191.44.47.1 to 191.44.47.126191.44.47.127126
96191.44.47.128/25191.44.47.129 to 191.44.47.254191.44.47.255126
97191.44.48.0/25191.44.48.1 to 191.44.48.126191.44.48.127126
98191.44.48.128/25191.44.48.129 to 191.44.48.254191.44.48.255126
99191.44.49.0/25191.44.49.1 to 191.44.49.126191.44.49.127126
100191.44.49.128/25191.44.49.129 to 191.44.49.254191.44.49.255126
101191.44.50.0/25191.44.50.1 to 191.44.50.126191.44.50.127126
102191.44.50.128/25191.44.50.129 to 191.44.50.254191.44.50.255126
103191.44.51.0/25191.44.51.1 to 191.44.51.126191.44.51.127126
104191.44.51.128/25191.44.51.129 to 191.44.51.254191.44.51.255126
105191.44.52.0/25191.44.52.1 to 191.44.52.126191.44.52.127126
106191.44.52.128/25191.44.52.129 to 191.44.52.254191.44.52.255126
107191.44.53.0/25191.44.53.1 to 191.44.53.126191.44.53.127126
108191.44.53.128/25191.44.53.129 to 191.44.53.254191.44.53.255126
109191.44.54.0/25191.44.54.1 to 191.44.54.126191.44.54.127126
110191.44.54.128/25191.44.54.129 to 191.44.54.254191.44.54.255126
111191.44.55.0/25191.44.55.1 to 191.44.55.126191.44.55.127126
112191.44.55.128/25191.44.55.129 to 191.44.55.254191.44.55.255126
113191.44.56.0/25191.44.56.1 to 191.44.56.126191.44.56.127126
114191.44.56.128/25191.44.56.129 to 191.44.56.254191.44.56.255126
115191.44.57.0/25191.44.57.1 to 191.44.57.126191.44.57.127126
116191.44.57.128/25191.44.57.129 to 191.44.57.254191.44.57.255126
117191.44.58.0/25191.44.58.1 to 191.44.58.126191.44.58.127126
118191.44.58.128/25191.44.58.129 to 191.44.58.254191.44.58.255126
119191.44.59.0/25191.44.59.1 to 191.44.59.126191.44.59.127126
120191.44.59.128/25191.44.59.129 to 191.44.59.254191.44.59.255126
121191.44.60.0/25191.44.60.1 to 191.44.60.126191.44.60.127126
122191.44.60.128/25191.44.60.129 to 191.44.60.254191.44.60.255126
123191.44.61.0/25191.44.61.1 to 191.44.61.126191.44.61.127126
124191.44.61.128/25191.44.61.129 to 191.44.61.254191.44.61.255126
125191.44.62.0/25191.44.62.1 to 191.44.62.126191.44.62.127126
126191.44.62.128/25191.44.62.129 to 191.44.62.254191.44.62.255126
127191.44.63.0/25191.44.63.1 to 191.44.63.126191.44.63.127126
128191.44.63.128/25191.44.63.129 to 191.44.63.254191.44.63.255126
129191.44.64.0/25191.44.64.1 to 191.44.64.126191.44.64.127126
130191.44.64.128/25191.44.64.129 to 191.44.64.254191.44.64.255126
131191.44.65.0/25191.44.65.1 to 191.44.65.126191.44.65.127126
132191.44.65.128/25191.44.65.129 to 191.44.65.254191.44.65.255126
133191.44.66.0/25191.44.66.1 to 191.44.66.126191.44.66.127126
134191.44.66.128/25191.44.66.129 to 191.44.66.254191.44.66.255126
135191.44.67.0/25191.44.67.1 to 191.44.67.126191.44.67.127126
136191.44.67.128/25191.44.67.129 to 191.44.67.254191.44.67.255126
137191.44.68.0/25191.44.68.1 to 191.44.68.126191.44.68.127126
138191.44.68.128/25191.44.68.129 to 191.44.68.254191.44.68.255126
139191.44.69.0/25191.44.69.1 to 191.44.69.126191.44.69.127126
140191.44.69.128/25191.44.69.129 to 191.44.69.254191.44.69.255126
141191.44.70.0/25191.44.70.1 to 191.44.70.126191.44.70.127126
142191.44.70.128/25191.44.70.129 to 191.44.70.254191.44.70.255126
143191.44.71.0/25191.44.71.1 to 191.44.71.126191.44.71.127126
144191.44.71.128/25191.44.71.129 to 191.44.71.254191.44.71.255126
145191.44.72.0/25191.44.72.1 to 191.44.72.126191.44.72.127126
146191.44.72.128/25191.44.72.129 to 191.44.72.254191.44.72.255126
147191.44.73.0/25191.44.73.1 to 191.44.73.126191.44.73.127126
148191.44.73.128/25191.44.73.129 to 191.44.73.254191.44.73.255126
149191.44.74.0/25191.44.74.1 to 191.44.74.126191.44.74.127126
150191.44.74.128/25191.44.74.129 to 191.44.74.254191.44.74.255126
151191.44.75.0/25191.44.75.1 to 191.44.75.126191.44.75.127126
152191.44.75.128/25191.44.75.129 to 191.44.75.254191.44.75.255126
153191.44.76.0/25191.44.76.1 to 191.44.76.126191.44.76.127126
154191.44.76.128/25191.44.76.129 to 191.44.76.254191.44.76.255126
155191.44.77.0/25191.44.77.1 to 191.44.77.126191.44.77.127126
156191.44.77.128/25191.44.77.129 to 191.44.77.254191.44.77.255126
157191.44.78.0/25191.44.78.1 to 191.44.78.126191.44.78.127126
158191.44.78.128/25191.44.78.129 to 191.44.78.254191.44.78.255126
159191.44.79.0/25191.44.79.1 to 191.44.79.126191.44.79.127126
160191.44.79.128/25191.44.79.129 to 191.44.79.254191.44.79.255126
161191.44.80.0/25191.44.80.1 to 191.44.80.126191.44.80.127126
162191.44.80.128/25191.44.80.129 to 191.44.80.254191.44.80.255126
163191.44.81.0/25191.44.81.1 to 191.44.81.126191.44.81.127126
164191.44.81.128/25191.44.81.129 to 191.44.81.254191.44.81.255126
165191.44.82.0/25191.44.82.1 to 191.44.82.126191.44.82.127126
166191.44.82.128/25191.44.82.129 to 191.44.82.254191.44.82.255126
167191.44.83.0/25191.44.83.1 to 191.44.83.126191.44.83.127126
168191.44.83.128/25191.44.83.129 to 191.44.83.254191.44.83.255126
169191.44.84.0/25191.44.84.1 to 191.44.84.126191.44.84.127126
170191.44.84.128/25191.44.84.129 to 191.44.84.254191.44.84.255126
171191.44.85.0/25191.44.85.1 to 191.44.85.126191.44.85.127126
172191.44.85.128/25191.44.85.129 to 191.44.85.254191.44.85.255126
173191.44.86.0/25191.44.86.1 to 191.44.86.126191.44.86.127126
174191.44.86.128/25191.44.86.129 to 191.44.86.254191.44.86.255126
175191.44.87.0/25191.44.87.1 to 191.44.87.126191.44.87.127126
176191.44.87.128/25191.44.87.129 to 191.44.87.254191.44.87.255126
177191.44.88.0/25191.44.88.1 to 191.44.88.126191.44.88.127126
178191.44.88.128/25191.44.88.129 to 191.44.88.254191.44.88.255126
179191.44.89.0/25191.44.89.1 to 191.44.89.126191.44.89.127126
180191.44.89.128/25191.44.89.129 to 191.44.89.254191.44.89.255126
181191.44.90.0/25191.44.90.1 to 191.44.90.126191.44.90.127126
182191.44.90.128/25191.44.90.129 to 191.44.90.254191.44.90.255126
183191.44.91.0/25191.44.91.1 to 191.44.91.126191.44.91.127126
184191.44.91.128/25191.44.91.129 to 191.44.91.254191.44.91.255126
185191.44.92.0/25191.44.92.1 to 191.44.92.126191.44.92.127126
186191.44.92.128/25191.44.92.129 to 191.44.92.254191.44.92.255126
187191.44.93.0/25191.44.93.1 to 191.44.93.126191.44.93.127126
188191.44.93.128/25191.44.93.129 to 191.44.93.254191.44.93.255126
189191.44.94.0/25191.44.94.1 to 191.44.94.126191.44.94.127126
190191.44.94.128/25191.44.94.129 to 191.44.94.254191.44.94.255126
191191.44.95.0/25191.44.95.1 to 191.44.95.126191.44.95.127126
192191.44.95.128/25191.44.95.129 to 191.44.95.254191.44.95.255126
193191.44.96.0/25191.44.96.1 to 191.44.96.126191.44.96.127126
194191.44.96.128/25191.44.96.129 to 191.44.96.254191.44.96.255126
195191.44.97.0/25191.44.97.1 to 191.44.97.126191.44.97.127126
196191.44.97.128/25191.44.97.129 to 191.44.97.254191.44.97.255126
197191.44.98.0/25191.44.98.1 to 191.44.98.126191.44.98.127126
198191.44.98.128/25191.44.98.129 to 191.44.98.254191.44.98.255126
199191.44.99.0/25191.44.99.1 to 191.44.99.126191.44.99.127126
200191.44.99.128/25191.44.99.129 to 191.44.99.254191.44.99.255126
201191.44.100.0/25191.44.100.1 to 191.44.100.126191.44.100.127126
202191.44.100.128/25191.44.100.129 to 191.44.100.254191.44.100.255126
203191.44.101.0/25191.44.101.1 to 191.44.101.126191.44.101.127126
204191.44.101.128/25191.44.101.129 to 191.44.101.254191.44.101.255126
205191.44.102.0/25191.44.102.1 to 191.44.102.126191.44.102.127126
206191.44.102.128/25191.44.102.129 to 191.44.102.254191.44.102.255126
207191.44.103.0/25191.44.103.1 to 191.44.103.126191.44.103.127126
208191.44.103.128/25191.44.103.129 to 191.44.103.254191.44.103.255126
209191.44.104.0/25191.44.104.1 to 191.44.104.126191.44.104.127126
210191.44.104.128/25191.44.104.129 to 191.44.104.254191.44.104.255126
211191.44.105.0/25191.44.105.1 to 191.44.105.126191.44.105.127126
212191.44.105.128/25191.44.105.129 to 191.44.105.254191.44.105.255126
213191.44.106.0/25191.44.106.1 to 191.44.106.126191.44.106.127126
214191.44.106.128/25191.44.106.129 to 191.44.106.254191.44.106.255126
215191.44.107.0/25191.44.107.1 to 191.44.107.126191.44.107.127126
216191.44.107.128/25191.44.107.129 to 191.44.107.254191.44.107.255126
217191.44.108.0/25191.44.108.1 to 191.44.108.126191.44.108.127126
218191.44.108.128/25191.44.108.129 to 191.44.108.254191.44.108.255126
219191.44.109.0/25191.44.109.1 to 191.44.109.126191.44.109.127126
220191.44.109.128/25191.44.109.129 to 191.44.109.254191.44.109.255126
221191.44.110.0/25191.44.110.1 to 191.44.110.126191.44.110.127126
222191.44.110.128/25191.44.110.129 to 191.44.110.254191.44.110.255126
223191.44.111.0/25191.44.111.1 to 191.44.111.126191.44.111.127126
224191.44.111.128/25191.44.111.129 to 191.44.111.254191.44.111.255126
225191.44.112.0/25191.44.112.1 to 191.44.112.126191.44.112.127126
226191.44.112.128/25191.44.112.129 to 191.44.112.254191.44.112.255126
227191.44.113.0/25191.44.113.1 to 191.44.113.126191.44.113.127126
228191.44.113.128/25191.44.113.129 to 191.44.113.254191.44.113.255126
229191.44.114.0/25191.44.114.1 to 191.44.114.126191.44.114.127126
230191.44.114.128/25191.44.114.129 to 191.44.114.254191.44.114.255126
231191.44.115.0/25191.44.115.1 to 191.44.115.126191.44.115.127126
232191.44.115.128/25191.44.115.129 to 191.44.115.254191.44.115.255126
233191.44.116.0/25191.44.116.1 to 191.44.116.126191.44.116.127126
234191.44.116.128/25191.44.116.129 to 191.44.116.254191.44.116.255126
235191.44.117.0/25191.44.117.1 to 191.44.117.126191.44.117.127126
236191.44.117.128/25191.44.117.129 to 191.44.117.254191.44.117.255126
237191.44.118.0/25191.44.118.1 to 191.44.118.126191.44.118.127126
238191.44.118.128/25191.44.118.129 to 191.44.118.254191.44.118.255126
239191.44.119.0/25191.44.119.1 to 191.44.119.126191.44.119.127126
240191.44.119.128/25191.44.119.129 to 191.44.119.254191.44.119.255126
241191.44.120.0/25191.44.120.1 to 191.44.120.126191.44.120.127126
242191.44.120.128/25191.44.120.129 to 191.44.120.254191.44.120.255126
243191.44.121.0/25191.44.121.1 to 191.44.121.126191.44.121.127126
244191.44.121.128/25191.44.121.129 to 191.44.121.254191.44.121.255126
245191.44.122.0/25191.44.122.1 to 191.44.122.126191.44.122.127126
246191.44.122.128/25191.44.122.129 to 191.44.122.254191.44.122.255126
247191.44.123.0/25191.44.123.1 to 191.44.123.126191.44.123.127126
248191.44.123.128/25191.44.123.129 to 191.44.123.254191.44.123.255126
249191.44.124.0/25191.44.124.1 to 191.44.124.126191.44.124.127126
250191.44.124.128/25191.44.124.129 to 191.44.124.254191.44.124.255126
251191.44.125.0/25191.44.125.1 to 191.44.125.126191.44.125.127126
252191.44.125.128/25191.44.125.129 to 191.44.125.254191.44.125.255126
253191.44.126.0/25191.44.126.1 to 191.44.126.126191.44.126.127126
254191.44.126.128/25191.44.126.129 to 191.44.126.254191.44.126.255126
255191.44.127.0/25191.44.127.1 to 191.44.127.126191.44.127.127126
256191.44.127.128/25191.44.127.129 to 191.44.127.254191.44.127.255126

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.