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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.

Network204.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
204.0.0.0
Broadcast address
207.255.255.255
First usable
204.0.0.1
Last usable
207.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
C (default /24)
As numbers
Hex CC000000 · Integer 3422552064 to 3489660927
Reverse DNS zones
204.in-addr.arpa
205.in-addr.arpa
206.in-addr.arpa
207.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001100.00000000.00000000.00000000204.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network11001100.00000000.00000000.00000000204.0.0.0
Broadcast11001111.11111111.11111111.11111111207.255.255.255
Split into smaller subnets/17
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

204.0.0.0/6 makes 2,048 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1204.0.0.0/17204.0.0.1 to 204.0.127.254204.0.127.25532,766
2204.0.128.0/17204.0.128.1 to 204.0.255.254204.0.255.25532,766
3204.1.0.0/17204.1.0.1 to 204.1.127.254204.1.127.25532,766
4204.1.128.0/17204.1.128.1 to 204.1.255.254204.1.255.25532,766
5204.2.0.0/17204.2.0.1 to 204.2.127.254204.2.127.25532,766
6204.2.128.0/17204.2.128.1 to 204.2.255.254204.2.255.25532,766
7204.3.0.0/17204.3.0.1 to 204.3.127.254204.3.127.25532,766
8204.3.128.0/17204.3.128.1 to 204.3.255.254204.3.255.25532,766
9204.4.0.0/17204.4.0.1 to 204.4.127.254204.4.127.25532,766
10204.4.128.0/17204.4.128.1 to 204.4.255.254204.4.255.25532,766
11204.5.0.0/17204.5.0.1 to 204.5.127.254204.5.127.25532,766
12204.5.128.0/17204.5.128.1 to 204.5.255.254204.5.255.25532,766
13204.6.0.0/17204.6.0.1 to 204.6.127.254204.6.127.25532,766
14204.6.128.0/17204.6.128.1 to 204.6.255.254204.6.255.25532,766
15204.7.0.0/17204.7.0.1 to 204.7.127.254204.7.127.25532,766
16204.7.128.0/17204.7.128.1 to 204.7.255.254204.7.255.25532,766
17204.8.0.0/17204.8.0.1 to 204.8.127.254204.8.127.25532,766
18204.8.128.0/17204.8.128.1 to 204.8.255.254204.8.255.25532,766
19204.9.0.0/17204.9.0.1 to 204.9.127.254204.9.127.25532,766
20204.9.128.0/17204.9.128.1 to 204.9.255.254204.9.255.25532,766
21204.10.0.0/17204.10.0.1 to 204.10.127.254204.10.127.25532,766
22204.10.128.0/17204.10.128.1 to 204.10.255.254204.10.255.25532,766
23204.11.0.0/17204.11.0.1 to 204.11.127.254204.11.127.25532,766
24204.11.128.0/17204.11.128.1 to 204.11.255.254204.11.255.25532,766
25204.12.0.0/17204.12.0.1 to 204.12.127.254204.12.127.25532,766
26204.12.128.0/17204.12.128.1 to 204.12.255.254204.12.255.25532,766
27204.13.0.0/17204.13.0.1 to 204.13.127.254204.13.127.25532,766
28204.13.128.0/17204.13.128.1 to 204.13.255.254204.13.255.25532,766
29204.14.0.0/17204.14.0.1 to 204.14.127.254204.14.127.25532,766
30204.14.128.0/17204.14.128.1 to 204.14.255.254204.14.255.25532,766
31204.15.0.0/17204.15.0.1 to 204.15.127.254204.15.127.25532,766
32204.15.128.0/17204.15.128.1 to 204.15.255.254204.15.255.25532,766
33204.16.0.0/17204.16.0.1 to 204.16.127.254204.16.127.25532,766
34204.16.128.0/17204.16.128.1 to 204.16.255.254204.16.255.25532,766
35204.17.0.0/17204.17.0.1 to 204.17.127.254204.17.127.25532,766
36204.17.128.0/17204.17.128.1 to 204.17.255.254204.17.255.25532,766
37204.18.0.0/17204.18.0.1 to 204.18.127.254204.18.127.25532,766
38204.18.128.0/17204.18.128.1 to 204.18.255.254204.18.255.25532,766
39204.19.0.0/17204.19.0.1 to 204.19.127.254204.19.127.25532,766
40204.19.128.0/17204.19.128.1 to 204.19.255.254204.19.255.25532,766
41204.20.0.0/17204.20.0.1 to 204.20.127.254204.20.127.25532,766
42204.20.128.0/17204.20.128.1 to 204.20.255.254204.20.255.25532,766
43204.21.0.0/17204.21.0.1 to 204.21.127.254204.21.127.25532,766
44204.21.128.0/17204.21.128.1 to 204.21.255.254204.21.255.25532,766
45204.22.0.0/17204.22.0.1 to 204.22.127.254204.22.127.25532,766
46204.22.128.0/17204.22.128.1 to 204.22.255.254204.22.255.25532,766
47204.23.0.0/17204.23.0.1 to 204.23.127.254204.23.127.25532,766
48204.23.128.0/17204.23.128.1 to 204.23.255.254204.23.255.25532,766
49204.24.0.0/17204.24.0.1 to 204.24.127.254204.24.127.25532,766
50204.24.128.0/17204.24.128.1 to 204.24.255.254204.24.255.25532,766
51204.25.0.0/17204.25.0.1 to 204.25.127.254204.25.127.25532,766
52204.25.128.0/17204.25.128.1 to 204.25.255.254204.25.255.25532,766
53204.26.0.0/17204.26.0.1 to 204.26.127.254204.26.127.25532,766
54204.26.128.0/17204.26.128.1 to 204.26.255.254204.26.255.25532,766
55204.27.0.0/17204.27.0.1 to 204.27.127.254204.27.127.25532,766
56204.27.128.0/17204.27.128.1 to 204.27.255.254204.27.255.25532,766
57204.28.0.0/17204.28.0.1 to 204.28.127.254204.28.127.25532,766
58204.28.128.0/17204.28.128.1 to 204.28.255.254204.28.255.25532,766
59204.29.0.0/17204.29.0.1 to 204.29.127.254204.29.127.25532,766
60204.29.128.0/17204.29.128.1 to 204.29.255.254204.29.255.25532,766
61204.30.0.0/17204.30.0.1 to 204.30.127.254204.30.127.25532,766
62204.30.128.0/17204.30.128.1 to 204.30.255.254204.30.255.25532,766
63204.31.0.0/17204.31.0.1 to 204.31.127.254204.31.127.25532,766
64204.31.128.0/17204.31.128.1 to 204.31.255.254204.31.255.25532,766
65204.32.0.0/17204.32.0.1 to 204.32.127.254204.32.127.25532,766
66204.32.128.0/17204.32.128.1 to 204.32.255.254204.32.255.25532,766
67204.33.0.0/17204.33.0.1 to 204.33.127.254204.33.127.25532,766
68204.33.128.0/17204.33.128.1 to 204.33.255.254204.33.255.25532,766
69204.34.0.0/17204.34.0.1 to 204.34.127.254204.34.127.25532,766
70204.34.128.0/17204.34.128.1 to 204.34.255.254204.34.255.25532,766
71204.35.0.0/17204.35.0.1 to 204.35.127.254204.35.127.25532,766
72204.35.128.0/17204.35.128.1 to 204.35.255.254204.35.255.25532,766
73204.36.0.0/17204.36.0.1 to 204.36.127.254204.36.127.25532,766
74204.36.128.0/17204.36.128.1 to 204.36.255.254204.36.255.25532,766
75204.37.0.0/17204.37.0.1 to 204.37.127.254204.37.127.25532,766
76204.37.128.0/17204.37.128.1 to 204.37.255.254204.37.255.25532,766
77204.38.0.0/17204.38.0.1 to 204.38.127.254204.38.127.25532,766
78204.38.128.0/17204.38.128.1 to 204.38.255.254204.38.255.25532,766
79204.39.0.0/17204.39.0.1 to 204.39.127.254204.39.127.25532,766
80204.39.128.0/17204.39.128.1 to 204.39.255.254204.39.255.25532,766
81204.40.0.0/17204.40.0.1 to 204.40.127.254204.40.127.25532,766
82204.40.128.0/17204.40.128.1 to 204.40.255.254204.40.255.25532,766
83204.41.0.0/17204.41.0.1 to 204.41.127.254204.41.127.25532,766
84204.41.128.0/17204.41.128.1 to 204.41.255.254204.41.255.25532,766
85204.42.0.0/17204.42.0.1 to 204.42.127.254204.42.127.25532,766
86204.42.128.0/17204.42.128.1 to 204.42.255.254204.42.255.25532,766
87204.43.0.0/17204.43.0.1 to 204.43.127.254204.43.127.25532,766
88204.43.128.0/17204.43.128.1 to 204.43.255.254204.43.255.25532,766
89204.44.0.0/17204.44.0.1 to 204.44.127.254204.44.127.25532,766
90204.44.128.0/17204.44.128.1 to 204.44.255.254204.44.255.25532,766
91204.45.0.0/17204.45.0.1 to 204.45.127.254204.45.127.25532,766
92204.45.128.0/17204.45.128.1 to 204.45.255.254204.45.255.25532,766
93204.46.0.0/17204.46.0.1 to 204.46.127.254204.46.127.25532,766
94204.46.128.0/17204.46.128.1 to 204.46.255.254204.46.255.25532,766
95204.47.0.0/17204.47.0.1 to 204.47.127.254204.47.127.25532,766
96204.47.128.0/17204.47.128.1 to 204.47.255.254204.47.255.25532,766
97204.48.0.0/17204.48.0.1 to 204.48.127.254204.48.127.25532,766
98204.48.128.0/17204.48.128.1 to 204.48.255.254204.48.255.25532,766
99204.49.0.0/17204.49.0.1 to 204.49.127.254204.49.127.25532,766
100204.49.128.0/17204.49.128.1 to 204.49.255.254204.49.255.25532,766
101204.50.0.0/17204.50.0.1 to 204.50.127.254204.50.127.25532,766
102204.50.128.0/17204.50.128.1 to 204.50.255.254204.50.255.25532,766
103204.51.0.0/17204.51.0.1 to 204.51.127.254204.51.127.25532,766
104204.51.128.0/17204.51.128.1 to 204.51.255.254204.51.255.25532,766
105204.52.0.0/17204.52.0.1 to 204.52.127.254204.52.127.25532,766
106204.52.128.0/17204.52.128.1 to 204.52.255.254204.52.255.25532,766
107204.53.0.0/17204.53.0.1 to 204.53.127.254204.53.127.25532,766
108204.53.128.0/17204.53.128.1 to 204.53.255.254204.53.255.25532,766
109204.54.0.0/17204.54.0.1 to 204.54.127.254204.54.127.25532,766
110204.54.128.0/17204.54.128.1 to 204.54.255.254204.54.255.25532,766
111204.55.0.0/17204.55.0.1 to 204.55.127.254204.55.127.25532,766
112204.55.128.0/17204.55.128.1 to 204.55.255.254204.55.255.25532,766
113204.56.0.0/17204.56.0.1 to 204.56.127.254204.56.127.25532,766
114204.56.128.0/17204.56.128.1 to 204.56.255.254204.56.255.25532,766
115204.57.0.0/17204.57.0.1 to 204.57.127.254204.57.127.25532,766
116204.57.128.0/17204.57.128.1 to 204.57.255.254204.57.255.25532,766
117204.58.0.0/17204.58.0.1 to 204.58.127.254204.58.127.25532,766
118204.58.128.0/17204.58.128.1 to 204.58.255.254204.58.255.25532,766
119204.59.0.0/17204.59.0.1 to 204.59.127.254204.59.127.25532,766
120204.59.128.0/17204.59.128.1 to 204.59.255.254204.59.255.25532,766
121204.60.0.0/17204.60.0.1 to 204.60.127.254204.60.127.25532,766
122204.60.128.0/17204.60.128.1 to 204.60.255.254204.60.255.25532,766
123204.61.0.0/17204.61.0.1 to 204.61.127.254204.61.127.25532,766
124204.61.128.0/17204.61.128.1 to 204.61.255.254204.61.255.25532,766
125204.62.0.0/17204.62.0.1 to 204.62.127.254204.62.127.25532,766
126204.62.128.0/17204.62.128.1 to 204.62.255.254204.62.255.25532,766
127204.63.0.0/17204.63.0.1 to 204.63.127.254204.63.127.25532,766
128204.63.128.0/17204.63.128.1 to 204.63.255.254204.63.255.25532,766
129204.64.0.0/17204.64.0.1 to 204.64.127.254204.64.127.25532,766
130204.64.128.0/17204.64.128.1 to 204.64.255.254204.64.255.25532,766
131204.65.0.0/17204.65.0.1 to 204.65.127.254204.65.127.25532,766
132204.65.128.0/17204.65.128.1 to 204.65.255.254204.65.255.25532,766
133204.66.0.0/17204.66.0.1 to 204.66.127.254204.66.127.25532,766
134204.66.128.0/17204.66.128.1 to 204.66.255.254204.66.255.25532,766
135204.67.0.0/17204.67.0.1 to 204.67.127.254204.67.127.25532,766
136204.67.128.0/17204.67.128.1 to 204.67.255.254204.67.255.25532,766
137204.68.0.0/17204.68.0.1 to 204.68.127.254204.68.127.25532,766
138204.68.128.0/17204.68.128.1 to 204.68.255.254204.68.255.25532,766
139204.69.0.0/17204.69.0.1 to 204.69.127.254204.69.127.25532,766
140204.69.128.0/17204.69.128.1 to 204.69.255.254204.69.255.25532,766
141204.70.0.0/17204.70.0.1 to 204.70.127.254204.70.127.25532,766
142204.70.128.0/17204.70.128.1 to 204.70.255.254204.70.255.25532,766
143204.71.0.0/17204.71.0.1 to 204.71.127.254204.71.127.25532,766
144204.71.128.0/17204.71.128.1 to 204.71.255.254204.71.255.25532,766
145204.72.0.0/17204.72.0.1 to 204.72.127.254204.72.127.25532,766
146204.72.128.0/17204.72.128.1 to 204.72.255.254204.72.255.25532,766
147204.73.0.0/17204.73.0.1 to 204.73.127.254204.73.127.25532,766
148204.73.128.0/17204.73.128.1 to 204.73.255.254204.73.255.25532,766
149204.74.0.0/17204.74.0.1 to 204.74.127.254204.74.127.25532,766
150204.74.128.0/17204.74.128.1 to 204.74.255.254204.74.255.25532,766
151204.75.0.0/17204.75.0.1 to 204.75.127.254204.75.127.25532,766
152204.75.128.0/17204.75.128.1 to 204.75.255.254204.75.255.25532,766
153204.76.0.0/17204.76.0.1 to 204.76.127.254204.76.127.25532,766
154204.76.128.0/17204.76.128.1 to 204.76.255.254204.76.255.25532,766
155204.77.0.0/17204.77.0.1 to 204.77.127.254204.77.127.25532,766
156204.77.128.0/17204.77.128.1 to 204.77.255.254204.77.255.25532,766
157204.78.0.0/17204.78.0.1 to 204.78.127.254204.78.127.25532,766
158204.78.128.0/17204.78.128.1 to 204.78.255.254204.78.255.25532,766
159204.79.0.0/17204.79.0.1 to 204.79.127.254204.79.127.25532,766
160204.79.128.0/17204.79.128.1 to 204.79.255.254204.79.255.25532,766
161204.80.0.0/17204.80.0.1 to 204.80.127.254204.80.127.25532,766
162204.80.128.0/17204.80.128.1 to 204.80.255.254204.80.255.25532,766
163204.81.0.0/17204.81.0.1 to 204.81.127.254204.81.127.25532,766
164204.81.128.0/17204.81.128.1 to 204.81.255.254204.81.255.25532,766
165204.82.0.0/17204.82.0.1 to 204.82.127.254204.82.127.25532,766
166204.82.128.0/17204.82.128.1 to 204.82.255.254204.82.255.25532,766
167204.83.0.0/17204.83.0.1 to 204.83.127.254204.83.127.25532,766
168204.83.128.0/17204.83.128.1 to 204.83.255.254204.83.255.25532,766
169204.84.0.0/17204.84.0.1 to 204.84.127.254204.84.127.25532,766
170204.84.128.0/17204.84.128.1 to 204.84.255.254204.84.255.25532,766
171204.85.0.0/17204.85.0.1 to 204.85.127.254204.85.127.25532,766
172204.85.128.0/17204.85.128.1 to 204.85.255.254204.85.255.25532,766
173204.86.0.0/17204.86.0.1 to 204.86.127.254204.86.127.25532,766
174204.86.128.0/17204.86.128.1 to 204.86.255.254204.86.255.25532,766
175204.87.0.0/17204.87.0.1 to 204.87.127.254204.87.127.25532,766
176204.87.128.0/17204.87.128.1 to 204.87.255.254204.87.255.25532,766
177204.88.0.0/17204.88.0.1 to 204.88.127.254204.88.127.25532,766
178204.88.128.0/17204.88.128.1 to 204.88.255.254204.88.255.25532,766
179204.89.0.0/17204.89.0.1 to 204.89.127.254204.89.127.25532,766
180204.89.128.0/17204.89.128.1 to 204.89.255.254204.89.255.25532,766
181204.90.0.0/17204.90.0.1 to 204.90.127.254204.90.127.25532,766
182204.90.128.0/17204.90.128.1 to 204.90.255.254204.90.255.25532,766
183204.91.0.0/17204.91.0.1 to 204.91.127.254204.91.127.25532,766
184204.91.128.0/17204.91.128.1 to 204.91.255.254204.91.255.25532,766
185204.92.0.0/17204.92.0.1 to 204.92.127.254204.92.127.25532,766
186204.92.128.0/17204.92.128.1 to 204.92.255.254204.92.255.25532,766
187204.93.0.0/17204.93.0.1 to 204.93.127.254204.93.127.25532,766
188204.93.128.0/17204.93.128.1 to 204.93.255.254204.93.255.25532,766
189204.94.0.0/17204.94.0.1 to 204.94.127.254204.94.127.25532,766
190204.94.128.0/17204.94.128.1 to 204.94.255.254204.94.255.25532,766
191204.95.0.0/17204.95.0.1 to 204.95.127.254204.95.127.25532,766
192204.95.128.0/17204.95.128.1 to 204.95.255.254204.95.255.25532,766
193204.96.0.0/17204.96.0.1 to 204.96.127.254204.96.127.25532,766
194204.96.128.0/17204.96.128.1 to 204.96.255.254204.96.255.25532,766
195204.97.0.0/17204.97.0.1 to 204.97.127.254204.97.127.25532,766
196204.97.128.0/17204.97.128.1 to 204.97.255.254204.97.255.25532,766
197204.98.0.0/17204.98.0.1 to 204.98.127.254204.98.127.25532,766
198204.98.128.0/17204.98.128.1 to 204.98.255.254204.98.255.25532,766
199204.99.0.0/17204.99.0.1 to 204.99.127.254204.99.127.25532,766
200204.99.128.0/17204.99.128.1 to 204.99.255.254204.99.255.25532,766
201204.100.0.0/17204.100.0.1 to 204.100.127.254204.100.127.25532,766
202204.100.128.0/17204.100.128.1 to 204.100.255.254204.100.255.25532,766
203204.101.0.0/17204.101.0.1 to 204.101.127.254204.101.127.25532,766
204204.101.128.0/17204.101.128.1 to 204.101.255.254204.101.255.25532,766
205204.102.0.0/17204.102.0.1 to 204.102.127.254204.102.127.25532,766
206204.102.128.0/17204.102.128.1 to 204.102.255.254204.102.255.25532,766
207204.103.0.0/17204.103.0.1 to 204.103.127.254204.103.127.25532,766
208204.103.128.0/17204.103.128.1 to 204.103.255.254204.103.255.25532,766
209204.104.0.0/17204.104.0.1 to 204.104.127.254204.104.127.25532,766
210204.104.128.0/17204.104.128.1 to 204.104.255.254204.104.255.25532,766
211204.105.0.0/17204.105.0.1 to 204.105.127.254204.105.127.25532,766
212204.105.128.0/17204.105.128.1 to 204.105.255.254204.105.255.25532,766
213204.106.0.0/17204.106.0.1 to 204.106.127.254204.106.127.25532,766
214204.106.128.0/17204.106.128.1 to 204.106.255.254204.106.255.25532,766
215204.107.0.0/17204.107.0.1 to 204.107.127.254204.107.127.25532,766
216204.107.128.0/17204.107.128.1 to 204.107.255.254204.107.255.25532,766
217204.108.0.0/17204.108.0.1 to 204.108.127.254204.108.127.25532,766
218204.108.128.0/17204.108.128.1 to 204.108.255.254204.108.255.25532,766
219204.109.0.0/17204.109.0.1 to 204.109.127.254204.109.127.25532,766
220204.109.128.0/17204.109.128.1 to 204.109.255.254204.109.255.25532,766
221204.110.0.0/17204.110.0.1 to 204.110.127.254204.110.127.25532,766
222204.110.128.0/17204.110.128.1 to 204.110.255.254204.110.255.25532,766
223204.111.0.0/17204.111.0.1 to 204.111.127.254204.111.127.25532,766
224204.111.128.0/17204.111.128.1 to 204.111.255.254204.111.255.25532,766
225204.112.0.0/17204.112.0.1 to 204.112.127.254204.112.127.25532,766
226204.112.128.0/17204.112.128.1 to 204.112.255.254204.112.255.25532,766
227204.113.0.0/17204.113.0.1 to 204.113.127.254204.113.127.25532,766
228204.113.128.0/17204.113.128.1 to 204.113.255.254204.113.255.25532,766
229204.114.0.0/17204.114.0.1 to 204.114.127.254204.114.127.25532,766
230204.114.128.0/17204.114.128.1 to 204.114.255.254204.114.255.25532,766
231204.115.0.0/17204.115.0.1 to 204.115.127.254204.115.127.25532,766
232204.115.128.0/17204.115.128.1 to 204.115.255.254204.115.255.25532,766
233204.116.0.0/17204.116.0.1 to 204.116.127.254204.116.127.25532,766
234204.116.128.0/17204.116.128.1 to 204.116.255.254204.116.255.25532,766
235204.117.0.0/17204.117.0.1 to 204.117.127.254204.117.127.25532,766
236204.117.128.0/17204.117.128.1 to 204.117.255.254204.117.255.25532,766
237204.118.0.0/17204.118.0.1 to 204.118.127.254204.118.127.25532,766
238204.118.128.0/17204.118.128.1 to 204.118.255.254204.118.255.25532,766
239204.119.0.0/17204.119.0.1 to 204.119.127.254204.119.127.25532,766
240204.119.128.0/17204.119.128.1 to 204.119.255.254204.119.255.25532,766
241204.120.0.0/17204.120.0.1 to 204.120.127.254204.120.127.25532,766
242204.120.128.0/17204.120.128.1 to 204.120.255.254204.120.255.25532,766
243204.121.0.0/17204.121.0.1 to 204.121.127.254204.121.127.25532,766
244204.121.128.0/17204.121.128.1 to 204.121.255.254204.121.255.25532,766
245204.122.0.0/17204.122.0.1 to 204.122.127.254204.122.127.25532,766
246204.122.128.0/17204.122.128.1 to 204.122.255.254204.122.255.25532,766
247204.123.0.0/17204.123.0.1 to 204.123.127.254204.123.127.25532,766
248204.123.128.0/17204.123.128.1 to 204.123.255.254204.123.255.25532,766
249204.124.0.0/17204.124.0.1 to 204.124.127.254204.124.127.25532,766
250204.124.128.0/17204.124.128.1 to 204.124.255.254204.124.255.25532,766
251204.125.0.0/17204.125.0.1 to 204.125.127.254204.125.127.25532,766
252204.125.128.0/17204.125.128.1 to 204.125.255.254204.125.255.25532,766
253204.126.0.0/17204.126.0.1 to 204.126.127.254204.126.127.25532,766
254204.126.128.0/17204.126.128.1 to 204.126.255.254204.126.255.25532,766
255204.127.0.0/17204.127.0.1 to 204.127.127.254204.127.127.25532,766
256204.127.128.0/17204.127.128.1 to 204.127.255.254204.127.255.25532,766

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.