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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.

Network204.78.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
204.78.0.0
Broadcast address
204.78.127.255
First usable
204.78.0.1
Last usable
204.78.127.254
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
C (default /24)
As numbers
Hex CC4E0000 · Integer 3427663872 to 3427696639
Reverse DNS zones
0.78.204.in-addr.arpa
1.78.204.in-addr.arpa
2.78.204.in-addr.arpa
3.78.204.in-addr.arpa
4.78.204.in-addr.arpa
5.78.204.in-addr.arpa
6.78.204.in-addr.arpa
7.78.204.in-addr.arpa
8.78.204.in-addr.arpa
9.78.204.in-addr.arpa
10.78.204.in-addr.arpa
11.78.204.in-addr.arpa
12.78.204.in-addr.arpa
13.78.204.in-addr.arpa
14.78.204.in-addr.arpa
15.78.204.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
Address11001100.01001110.00000000.00000000204.78.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11001100.01001110.00000000.00000000204.78.0.0
Broadcast11001100.01001110.01111111.11111111204.78.127.255
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)

204.78.0.0/17 makes 256 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1204.78.0.0/25204.78.0.1 to 204.78.0.126204.78.0.127126
2204.78.0.128/25204.78.0.129 to 204.78.0.254204.78.0.255126
3204.78.1.0/25204.78.1.1 to 204.78.1.126204.78.1.127126
4204.78.1.128/25204.78.1.129 to 204.78.1.254204.78.1.255126
5204.78.2.0/25204.78.2.1 to 204.78.2.126204.78.2.127126
6204.78.2.128/25204.78.2.129 to 204.78.2.254204.78.2.255126
7204.78.3.0/25204.78.3.1 to 204.78.3.126204.78.3.127126
8204.78.3.128/25204.78.3.129 to 204.78.3.254204.78.3.255126
9204.78.4.0/25204.78.4.1 to 204.78.4.126204.78.4.127126
10204.78.4.128/25204.78.4.129 to 204.78.4.254204.78.4.255126
11204.78.5.0/25204.78.5.1 to 204.78.5.126204.78.5.127126
12204.78.5.128/25204.78.5.129 to 204.78.5.254204.78.5.255126
13204.78.6.0/25204.78.6.1 to 204.78.6.126204.78.6.127126
14204.78.6.128/25204.78.6.129 to 204.78.6.254204.78.6.255126
15204.78.7.0/25204.78.7.1 to 204.78.7.126204.78.7.127126
16204.78.7.128/25204.78.7.129 to 204.78.7.254204.78.7.255126
17204.78.8.0/25204.78.8.1 to 204.78.8.126204.78.8.127126
18204.78.8.128/25204.78.8.129 to 204.78.8.254204.78.8.255126
19204.78.9.0/25204.78.9.1 to 204.78.9.126204.78.9.127126
20204.78.9.128/25204.78.9.129 to 204.78.9.254204.78.9.255126
21204.78.10.0/25204.78.10.1 to 204.78.10.126204.78.10.127126
22204.78.10.128/25204.78.10.129 to 204.78.10.254204.78.10.255126
23204.78.11.0/25204.78.11.1 to 204.78.11.126204.78.11.127126
24204.78.11.128/25204.78.11.129 to 204.78.11.254204.78.11.255126
25204.78.12.0/25204.78.12.1 to 204.78.12.126204.78.12.127126
26204.78.12.128/25204.78.12.129 to 204.78.12.254204.78.12.255126
27204.78.13.0/25204.78.13.1 to 204.78.13.126204.78.13.127126
28204.78.13.128/25204.78.13.129 to 204.78.13.254204.78.13.255126
29204.78.14.0/25204.78.14.1 to 204.78.14.126204.78.14.127126
30204.78.14.128/25204.78.14.129 to 204.78.14.254204.78.14.255126
31204.78.15.0/25204.78.15.1 to 204.78.15.126204.78.15.127126
32204.78.15.128/25204.78.15.129 to 204.78.15.254204.78.15.255126
33204.78.16.0/25204.78.16.1 to 204.78.16.126204.78.16.127126
34204.78.16.128/25204.78.16.129 to 204.78.16.254204.78.16.255126
35204.78.17.0/25204.78.17.1 to 204.78.17.126204.78.17.127126
36204.78.17.128/25204.78.17.129 to 204.78.17.254204.78.17.255126
37204.78.18.0/25204.78.18.1 to 204.78.18.126204.78.18.127126
38204.78.18.128/25204.78.18.129 to 204.78.18.254204.78.18.255126
39204.78.19.0/25204.78.19.1 to 204.78.19.126204.78.19.127126
40204.78.19.128/25204.78.19.129 to 204.78.19.254204.78.19.255126
41204.78.20.0/25204.78.20.1 to 204.78.20.126204.78.20.127126
42204.78.20.128/25204.78.20.129 to 204.78.20.254204.78.20.255126
43204.78.21.0/25204.78.21.1 to 204.78.21.126204.78.21.127126
44204.78.21.128/25204.78.21.129 to 204.78.21.254204.78.21.255126
45204.78.22.0/25204.78.22.1 to 204.78.22.126204.78.22.127126
46204.78.22.128/25204.78.22.129 to 204.78.22.254204.78.22.255126
47204.78.23.0/25204.78.23.1 to 204.78.23.126204.78.23.127126
48204.78.23.128/25204.78.23.129 to 204.78.23.254204.78.23.255126
49204.78.24.0/25204.78.24.1 to 204.78.24.126204.78.24.127126
50204.78.24.128/25204.78.24.129 to 204.78.24.254204.78.24.255126
51204.78.25.0/25204.78.25.1 to 204.78.25.126204.78.25.127126
52204.78.25.128/25204.78.25.129 to 204.78.25.254204.78.25.255126
53204.78.26.0/25204.78.26.1 to 204.78.26.126204.78.26.127126
54204.78.26.128/25204.78.26.129 to 204.78.26.254204.78.26.255126
55204.78.27.0/25204.78.27.1 to 204.78.27.126204.78.27.127126
56204.78.27.128/25204.78.27.129 to 204.78.27.254204.78.27.255126
57204.78.28.0/25204.78.28.1 to 204.78.28.126204.78.28.127126
58204.78.28.128/25204.78.28.129 to 204.78.28.254204.78.28.255126
59204.78.29.0/25204.78.29.1 to 204.78.29.126204.78.29.127126
60204.78.29.128/25204.78.29.129 to 204.78.29.254204.78.29.255126
61204.78.30.0/25204.78.30.1 to 204.78.30.126204.78.30.127126
62204.78.30.128/25204.78.30.129 to 204.78.30.254204.78.30.255126
63204.78.31.0/25204.78.31.1 to 204.78.31.126204.78.31.127126
64204.78.31.128/25204.78.31.129 to 204.78.31.254204.78.31.255126
65204.78.32.0/25204.78.32.1 to 204.78.32.126204.78.32.127126
66204.78.32.128/25204.78.32.129 to 204.78.32.254204.78.32.255126
67204.78.33.0/25204.78.33.1 to 204.78.33.126204.78.33.127126
68204.78.33.128/25204.78.33.129 to 204.78.33.254204.78.33.255126
69204.78.34.0/25204.78.34.1 to 204.78.34.126204.78.34.127126
70204.78.34.128/25204.78.34.129 to 204.78.34.254204.78.34.255126
71204.78.35.0/25204.78.35.1 to 204.78.35.126204.78.35.127126
72204.78.35.128/25204.78.35.129 to 204.78.35.254204.78.35.255126
73204.78.36.0/25204.78.36.1 to 204.78.36.126204.78.36.127126
74204.78.36.128/25204.78.36.129 to 204.78.36.254204.78.36.255126
75204.78.37.0/25204.78.37.1 to 204.78.37.126204.78.37.127126
76204.78.37.128/25204.78.37.129 to 204.78.37.254204.78.37.255126
77204.78.38.0/25204.78.38.1 to 204.78.38.126204.78.38.127126
78204.78.38.128/25204.78.38.129 to 204.78.38.254204.78.38.255126
79204.78.39.0/25204.78.39.1 to 204.78.39.126204.78.39.127126
80204.78.39.128/25204.78.39.129 to 204.78.39.254204.78.39.255126
81204.78.40.0/25204.78.40.1 to 204.78.40.126204.78.40.127126
82204.78.40.128/25204.78.40.129 to 204.78.40.254204.78.40.255126
83204.78.41.0/25204.78.41.1 to 204.78.41.126204.78.41.127126
84204.78.41.128/25204.78.41.129 to 204.78.41.254204.78.41.255126
85204.78.42.0/25204.78.42.1 to 204.78.42.126204.78.42.127126
86204.78.42.128/25204.78.42.129 to 204.78.42.254204.78.42.255126
87204.78.43.0/25204.78.43.1 to 204.78.43.126204.78.43.127126
88204.78.43.128/25204.78.43.129 to 204.78.43.254204.78.43.255126
89204.78.44.0/25204.78.44.1 to 204.78.44.126204.78.44.127126
90204.78.44.128/25204.78.44.129 to 204.78.44.254204.78.44.255126
91204.78.45.0/25204.78.45.1 to 204.78.45.126204.78.45.127126
92204.78.45.128/25204.78.45.129 to 204.78.45.254204.78.45.255126
93204.78.46.0/25204.78.46.1 to 204.78.46.126204.78.46.127126
94204.78.46.128/25204.78.46.129 to 204.78.46.254204.78.46.255126
95204.78.47.0/25204.78.47.1 to 204.78.47.126204.78.47.127126
96204.78.47.128/25204.78.47.129 to 204.78.47.254204.78.47.255126
97204.78.48.0/25204.78.48.1 to 204.78.48.126204.78.48.127126
98204.78.48.128/25204.78.48.129 to 204.78.48.254204.78.48.255126
99204.78.49.0/25204.78.49.1 to 204.78.49.126204.78.49.127126
100204.78.49.128/25204.78.49.129 to 204.78.49.254204.78.49.255126
101204.78.50.0/25204.78.50.1 to 204.78.50.126204.78.50.127126
102204.78.50.128/25204.78.50.129 to 204.78.50.254204.78.50.255126
103204.78.51.0/25204.78.51.1 to 204.78.51.126204.78.51.127126
104204.78.51.128/25204.78.51.129 to 204.78.51.254204.78.51.255126
105204.78.52.0/25204.78.52.1 to 204.78.52.126204.78.52.127126
106204.78.52.128/25204.78.52.129 to 204.78.52.254204.78.52.255126
107204.78.53.0/25204.78.53.1 to 204.78.53.126204.78.53.127126
108204.78.53.128/25204.78.53.129 to 204.78.53.254204.78.53.255126
109204.78.54.0/25204.78.54.1 to 204.78.54.126204.78.54.127126
110204.78.54.128/25204.78.54.129 to 204.78.54.254204.78.54.255126
111204.78.55.0/25204.78.55.1 to 204.78.55.126204.78.55.127126
112204.78.55.128/25204.78.55.129 to 204.78.55.254204.78.55.255126
113204.78.56.0/25204.78.56.1 to 204.78.56.126204.78.56.127126
114204.78.56.128/25204.78.56.129 to 204.78.56.254204.78.56.255126
115204.78.57.0/25204.78.57.1 to 204.78.57.126204.78.57.127126
116204.78.57.128/25204.78.57.129 to 204.78.57.254204.78.57.255126
117204.78.58.0/25204.78.58.1 to 204.78.58.126204.78.58.127126
118204.78.58.128/25204.78.58.129 to 204.78.58.254204.78.58.255126
119204.78.59.0/25204.78.59.1 to 204.78.59.126204.78.59.127126
120204.78.59.128/25204.78.59.129 to 204.78.59.254204.78.59.255126
121204.78.60.0/25204.78.60.1 to 204.78.60.126204.78.60.127126
122204.78.60.128/25204.78.60.129 to 204.78.60.254204.78.60.255126
123204.78.61.0/25204.78.61.1 to 204.78.61.126204.78.61.127126
124204.78.61.128/25204.78.61.129 to 204.78.61.254204.78.61.255126
125204.78.62.0/25204.78.62.1 to 204.78.62.126204.78.62.127126
126204.78.62.128/25204.78.62.129 to 204.78.62.254204.78.62.255126
127204.78.63.0/25204.78.63.1 to 204.78.63.126204.78.63.127126
128204.78.63.128/25204.78.63.129 to 204.78.63.254204.78.63.255126
129204.78.64.0/25204.78.64.1 to 204.78.64.126204.78.64.127126
130204.78.64.128/25204.78.64.129 to 204.78.64.254204.78.64.255126
131204.78.65.0/25204.78.65.1 to 204.78.65.126204.78.65.127126
132204.78.65.128/25204.78.65.129 to 204.78.65.254204.78.65.255126
133204.78.66.0/25204.78.66.1 to 204.78.66.126204.78.66.127126
134204.78.66.128/25204.78.66.129 to 204.78.66.254204.78.66.255126
135204.78.67.0/25204.78.67.1 to 204.78.67.126204.78.67.127126
136204.78.67.128/25204.78.67.129 to 204.78.67.254204.78.67.255126
137204.78.68.0/25204.78.68.1 to 204.78.68.126204.78.68.127126
138204.78.68.128/25204.78.68.129 to 204.78.68.254204.78.68.255126
139204.78.69.0/25204.78.69.1 to 204.78.69.126204.78.69.127126
140204.78.69.128/25204.78.69.129 to 204.78.69.254204.78.69.255126
141204.78.70.0/25204.78.70.1 to 204.78.70.126204.78.70.127126
142204.78.70.128/25204.78.70.129 to 204.78.70.254204.78.70.255126
143204.78.71.0/25204.78.71.1 to 204.78.71.126204.78.71.127126
144204.78.71.128/25204.78.71.129 to 204.78.71.254204.78.71.255126
145204.78.72.0/25204.78.72.1 to 204.78.72.126204.78.72.127126
146204.78.72.128/25204.78.72.129 to 204.78.72.254204.78.72.255126
147204.78.73.0/25204.78.73.1 to 204.78.73.126204.78.73.127126
148204.78.73.128/25204.78.73.129 to 204.78.73.254204.78.73.255126
149204.78.74.0/25204.78.74.1 to 204.78.74.126204.78.74.127126
150204.78.74.128/25204.78.74.129 to 204.78.74.254204.78.74.255126
151204.78.75.0/25204.78.75.1 to 204.78.75.126204.78.75.127126
152204.78.75.128/25204.78.75.129 to 204.78.75.254204.78.75.255126
153204.78.76.0/25204.78.76.1 to 204.78.76.126204.78.76.127126
154204.78.76.128/25204.78.76.129 to 204.78.76.254204.78.76.255126
155204.78.77.0/25204.78.77.1 to 204.78.77.126204.78.77.127126
156204.78.77.128/25204.78.77.129 to 204.78.77.254204.78.77.255126
157204.78.78.0/25204.78.78.1 to 204.78.78.126204.78.78.127126
158204.78.78.128/25204.78.78.129 to 204.78.78.254204.78.78.255126
159204.78.79.0/25204.78.79.1 to 204.78.79.126204.78.79.127126
160204.78.79.128/25204.78.79.129 to 204.78.79.254204.78.79.255126
161204.78.80.0/25204.78.80.1 to 204.78.80.126204.78.80.127126
162204.78.80.128/25204.78.80.129 to 204.78.80.254204.78.80.255126
163204.78.81.0/25204.78.81.1 to 204.78.81.126204.78.81.127126
164204.78.81.128/25204.78.81.129 to 204.78.81.254204.78.81.255126
165204.78.82.0/25204.78.82.1 to 204.78.82.126204.78.82.127126
166204.78.82.128/25204.78.82.129 to 204.78.82.254204.78.82.255126
167204.78.83.0/25204.78.83.1 to 204.78.83.126204.78.83.127126
168204.78.83.128/25204.78.83.129 to 204.78.83.254204.78.83.255126
169204.78.84.0/25204.78.84.1 to 204.78.84.126204.78.84.127126
170204.78.84.128/25204.78.84.129 to 204.78.84.254204.78.84.255126
171204.78.85.0/25204.78.85.1 to 204.78.85.126204.78.85.127126
172204.78.85.128/25204.78.85.129 to 204.78.85.254204.78.85.255126
173204.78.86.0/25204.78.86.1 to 204.78.86.126204.78.86.127126
174204.78.86.128/25204.78.86.129 to 204.78.86.254204.78.86.255126
175204.78.87.0/25204.78.87.1 to 204.78.87.126204.78.87.127126
176204.78.87.128/25204.78.87.129 to 204.78.87.254204.78.87.255126
177204.78.88.0/25204.78.88.1 to 204.78.88.126204.78.88.127126
178204.78.88.128/25204.78.88.129 to 204.78.88.254204.78.88.255126
179204.78.89.0/25204.78.89.1 to 204.78.89.126204.78.89.127126
180204.78.89.128/25204.78.89.129 to 204.78.89.254204.78.89.255126
181204.78.90.0/25204.78.90.1 to 204.78.90.126204.78.90.127126
182204.78.90.128/25204.78.90.129 to 204.78.90.254204.78.90.255126
183204.78.91.0/25204.78.91.1 to 204.78.91.126204.78.91.127126
184204.78.91.128/25204.78.91.129 to 204.78.91.254204.78.91.255126
185204.78.92.0/25204.78.92.1 to 204.78.92.126204.78.92.127126
186204.78.92.128/25204.78.92.129 to 204.78.92.254204.78.92.255126
187204.78.93.0/25204.78.93.1 to 204.78.93.126204.78.93.127126
188204.78.93.128/25204.78.93.129 to 204.78.93.254204.78.93.255126
189204.78.94.0/25204.78.94.1 to 204.78.94.126204.78.94.127126
190204.78.94.128/25204.78.94.129 to 204.78.94.254204.78.94.255126
191204.78.95.0/25204.78.95.1 to 204.78.95.126204.78.95.127126
192204.78.95.128/25204.78.95.129 to 204.78.95.254204.78.95.255126
193204.78.96.0/25204.78.96.1 to 204.78.96.126204.78.96.127126
194204.78.96.128/25204.78.96.129 to 204.78.96.254204.78.96.255126
195204.78.97.0/25204.78.97.1 to 204.78.97.126204.78.97.127126
196204.78.97.128/25204.78.97.129 to 204.78.97.254204.78.97.255126
197204.78.98.0/25204.78.98.1 to 204.78.98.126204.78.98.127126
198204.78.98.128/25204.78.98.129 to 204.78.98.254204.78.98.255126
199204.78.99.0/25204.78.99.1 to 204.78.99.126204.78.99.127126
200204.78.99.128/25204.78.99.129 to 204.78.99.254204.78.99.255126
201204.78.100.0/25204.78.100.1 to 204.78.100.126204.78.100.127126
202204.78.100.128/25204.78.100.129 to 204.78.100.254204.78.100.255126
203204.78.101.0/25204.78.101.1 to 204.78.101.126204.78.101.127126
204204.78.101.128/25204.78.101.129 to 204.78.101.254204.78.101.255126
205204.78.102.0/25204.78.102.1 to 204.78.102.126204.78.102.127126
206204.78.102.128/25204.78.102.129 to 204.78.102.254204.78.102.255126
207204.78.103.0/25204.78.103.1 to 204.78.103.126204.78.103.127126
208204.78.103.128/25204.78.103.129 to 204.78.103.254204.78.103.255126
209204.78.104.0/25204.78.104.1 to 204.78.104.126204.78.104.127126
210204.78.104.128/25204.78.104.129 to 204.78.104.254204.78.104.255126
211204.78.105.0/25204.78.105.1 to 204.78.105.126204.78.105.127126
212204.78.105.128/25204.78.105.129 to 204.78.105.254204.78.105.255126
213204.78.106.0/25204.78.106.1 to 204.78.106.126204.78.106.127126
214204.78.106.128/25204.78.106.129 to 204.78.106.254204.78.106.255126
215204.78.107.0/25204.78.107.1 to 204.78.107.126204.78.107.127126
216204.78.107.128/25204.78.107.129 to 204.78.107.254204.78.107.255126
217204.78.108.0/25204.78.108.1 to 204.78.108.126204.78.108.127126
218204.78.108.128/25204.78.108.129 to 204.78.108.254204.78.108.255126
219204.78.109.0/25204.78.109.1 to 204.78.109.126204.78.109.127126
220204.78.109.128/25204.78.109.129 to 204.78.109.254204.78.109.255126
221204.78.110.0/25204.78.110.1 to 204.78.110.126204.78.110.127126
222204.78.110.128/25204.78.110.129 to 204.78.110.254204.78.110.255126
223204.78.111.0/25204.78.111.1 to 204.78.111.126204.78.111.127126
224204.78.111.128/25204.78.111.129 to 204.78.111.254204.78.111.255126
225204.78.112.0/25204.78.112.1 to 204.78.112.126204.78.112.127126
226204.78.112.128/25204.78.112.129 to 204.78.112.254204.78.112.255126
227204.78.113.0/25204.78.113.1 to 204.78.113.126204.78.113.127126
228204.78.113.128/25204.78.113.129 to 204.78.113.254204.78.113.255126
229204.78.114.0/25204.78.114.1 to 204.78.114.126204.78.114.127126
230204.78.114.128/25204.78.114.129 to 204.78.114.254204.78.114.255126
231204.78.115.0/25204.78.115.1 to 204.78.115.126204.78.115.127126
232204.78.115.128/25204.78.115.129 to 204.78.115.254204.78.115.255126
233204.78.116.0/25204.78.116.1 to 204.78.116.126204.78.116.127126
234204.78.116.128/25204.78.116.129 to 204.78.116.254204.78.116.255126
235204.78.117.0/25204.78.117.1 to 204.78.117.126204.78.117.127126
236204.78.117.128/25204.78.117.129 to 204.78.117.254204.78.117.255126
237204.78.118.0/25204.78.118.1 to 204.78.118.126204.78.118.127126
238204.78.118.128/25204.78.118.129 to 204.78.118.254204.78.118.255126
239204.78.119.0/25204.78.119.1 to 204.78.119.126204.78.119.127126
240204.78.119.128/25204.78.119.129 to 204.78.119.254204.78.119.255126
241204.78.120.0/25204.78.120.1 to 204.78.120.126204.78.120.127126
242204.78.120.128/25204.78.120.129 to 204.78.120.254204.78.120.255126
243204.78.121.0/25204.78.121.1 to 204.78.121.126204.78.121.127126
244204.78.121.128/25204.78.121.129 to 204.78.121.254204.78.121.255126
245204.78.122.0/25204.78.122.1 to 204.78.122.126204.78.122.127126
246204.78.122.128/25204.78.122.129 to 204.78.122.254204.78.122.255126
247204.78.123.0/25204.78.123.1 to 204.78.123.126204.78.123.127126
248204.78.123.128/25204.78.123.129 to 204.78.123.254204.78.123.255126
249204.78.124.0/25204.78.124.1 to 204.78.124.126204.78.124.127126
250204.78.124.128/25204.78.124.129 to 204.78.124.254204.78.124.255126
251204.78.125.0/25204.78.125.1 to 204.78.125.126204.78.125.127126
252204.78.125.128/25204.78.125.129 to 204.78.125.254204.78.125.255126
253204.78.126.0/25204.78.126.1 to 204.78.126.126204.78.126.127126
254204.78.126.128/25204.78.126.129 to 204.78.126.254204.78.126.255126
255204.78.127.0/25204.78.127.1 to 204.78.127.126204.78.127.127126
256204.78.127.128/25204.78.127.129 to 204.78.127.254204.78.127.255126

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.