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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.

Network203.78.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
203.78.0.0
Broadcast address
203.79.255.255
First usable
203.78.0.1
Last usable
203.79.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
C (default /24)
As numbers
Hex CB4E0000 · Integer 3410886656 to 3411017727
Reverse DNS zones
78.203.in-addr.arpa
79.203.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001011.01001110.00000000.00000000203.78.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11001011.01001110.00000000.00000000203.78.0.0
Broadcast11001011.01001111.11111111.11111111203.79.255.255
Split into smaller subnets/26
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

203.78.0.0/15 makes 2,048 subnets of /26; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1203.78.0.0/26203.78.0.1 to 203.78.0.62203.78.0.6362
2203.78.0.64/26203.78.0.65 to 203.78.0.126203.78.0.12762
3203.78.0.128/26203.78.0.129 to 203.78.0.190203.78.0.19162
4203.78.0.192/26203.78.0.193 to 203.78.0.254203.78.0.25562
5203.78.1.0/26203.78.1.1 to 203.78.1.62203.78.1.6362
6203.78.1.64/26203.78.1.65 to 203.78.1.126203.78.1.12762
7203.78.1.128/26203.78.1.129 to 203.78.1.190203.78.1.19162
8203.78.1.192/26203.78.1.193 to 203.78.1.254203.78.1.25562
9203.78.2.0/26203.78.2.1 to 203.78.2.62203.78.2.6362
10203.78.2.64/26203.78.2.65 to 203.78.2.126203.78.2.12762
11203.78.2.128/26203.78.2.129 to 203.78.2.190203.78.2.19162
12203.78.2.192/26203.78.2.193 to 203.78.2.254203.78.2.25562
13203.78.3.0/26203.78.3.1 to 203.78.3.62203.78.3.6362
14203.78.3.64/26203.78.3.65 to 203.78.3.126203.78.3.12762
15203.78.3.128/26203.78.3.129 to 203.78.3.190203.78.3.19162
16203.78.3.192/26203.78.3.193 to 203.78.3.254203.78.3.25562
17203.78.4.0/26203.78.4.1 to 203.78.4.62203.78.4.6362
18203.78.4.64/26203.78.4.65 to 203.78.4.126203.78.4.12762
19203.78.4.128/26203.78.4.129 to 203.78.4.190203.78.4.19162
20203.78.4.192/26203.78.4.193 to 203.78.4.254203.78.4.25562
21203.78.5.0/26203.78.5.1 to 203.78.5.62203.78.5.6362
22203.78.5.64/26203.78.5.65 to 203.78.5.126203.78.5.12762
23203.78.5.128/26203.78.5.129 to 203.78.5.190203.78.5.19162
24203.78.5.192/26203.78.5.193 to 203.78.5.254203.78.5.25562
25203.78.6.0/26203.78.6.1 to 203.78.6.62203.78.6.6362
26203.78.6.64/26203.78.6.65 to 203.78.6.126203.78.6.12762
27203.78.6.128/26203.78.6.129 to 203.78.6.190203.78.6.19162
28203.78.6.192/26203.78.6.193 to 203.78.6.254203.78.6.25562
29203.78.7.0/26203.78.7.1 to 203.78.7.62203.78.7.6362
30203.78.7.64/26203.78.7.65 to 203.78.7.126203.78.7.12762
31203.78.7.128/26203.78.7.129 to 203.78.7.190203.78.7.19162
32203.78.7.192/26203.78.7.193 to 203.78.7.254203.78.7.25562
33203.78.8.0/26203.78.8.1 to 203.78.8.62203.78.8.6362
34203.78.8.64/26203.78.8.65 to 203.78.8.126203.78.8.12762
35203.78.8.128/26203.78.8.129 to 203.78.8.190203.78.8.19162
36203.78.8.192/26203.78.8.193 to 203.78.8.254203.78.8.25562
37203.78.9.0/26203.78.9.1 to 203.78.9.62203.78.9.6362
38203.78.9.64/26203.78.9.65 to 203.78.9.126203.78.9.12762
39203.78.9.128/26203.78.9.129 to 203.78.9.190203.78.9.19162
40203.78.9.192/26203.78.9.193 to 203.78.9.254203.78.9.25562
41203.78.10.0/26203.78.10.1 to 203.78.10.62203.78.10.6362
42203.78.10.64/26203.78.10.65 to 203.78.10.126203.78.10.12762
43203.78.10.128/26203.78.10.129 to 203.78.10.190203.78.10.19162
44203.78.10.192/26203.78.10.193 to 203.78.10.254203.78.10.25562
45203.78.11.0/26203.78.11.1 to 203.78.11.62203.78.11.6362
46203.78.11.64/26203.78.11.65 to 203.78.11.126203.78.11.12762
47203.78.11.128/26203.78.11.129 to 203.78.11.190203.78.11.19162
48203.78.11.192/26203.78.11.193 to 203.78.11.254203.78.11.25562
49203.78.12.0/26203.78.12.1 to 203.78.12.62203.78.12.6362
50203.78.12.64/26203.78.12.65 to 203.78.12.126203.78.12.12762
51203.78.12.128/26203.78.12.129 to 203.78.12.190203.78.12.19162
52203.78.12.192/26203.78.12.193 to 203.78.12.254203.78.12.25562
53203.78.13.0/26203.78.13.1 to 203.78.13.62203.78.13.6362
54203.78.13.64/26203.78.13.65 to 203.78.13.126203.78.13.12762
55203.78.13.128/26203.78.13.129 to 203.78.13.190203.78.13.19162
56203.78.13.192/26203.78.13.193 to 203.78.13.254203.78.13.25562
57203.78.14.0/26203.78.14.1 to 203.78.14.62203.78.14.6362
58203.78.14.64/26203.78.14.65 to 203.78.14.126203.78.14.12762
59203.78.14.128/26203.78.14.129 to 203.78.14.190203.78.14.19162
60203.78.14.192/26203.78.14.193 to 203.78.14.254203.78.14.25562
61203.78.15.0/26203.78.15.1 to 203.78.15.62203.78.15.6362
62203.78.15.64/26203.78.15.65 to 203.78.15.126203.78.15.12762
63203.78.15.128/26203.78.15.129 to 203.78.15.190203.78.15.19162
64203.78.15.192/26203.78.15.193 to 203.78.15.254203.78.15.25562
65203.78.16.0/26203.78.16.1 to 203.78.16.62203.78.16.6362
66203.78.16.64/26203.78.16.65 to 203.78.16.126203.78.16.12762
67203.78.16.128/26203.78.16.129 to 203.78.16.190203.78.16.19162
68203.78.16.192/26203.78.16.193 to 203.78.16.254203.78.16.25562
69203.78.17.0/26203.78.17.1 to 203.78.17.62203.78.17.6362
70203.78.17.64/26203.78.17.65 to 203.78.17.126203.78.17.12762
71203.78.17.128/26203.78.17.129 to 203.78.17.190203.78.17.19162
72203.78.17.192/26203.78.17.193 to 203.78.17.254203.78.17.25562
73203.78.18.0/26203.78.18.1 to 203.78.18.62203.78.18.6362
74203.78.18.64/26203.78.18.65 to 203.78.18.126203.78.18.12762
75203.78.18.128/26203.78.18.129 to 203.78.18.190203.78.18.19162
76203.78.18.192/26203.78.18.193 to 203.78.18.254203.78.18.25562
77203.78.19.0/26203.78.19.1 to 203.78.19.62203.78.19.6362
78203.78.19.64/26203.78.19.65 to 203.78.19.126203.78.19.12762
79203.78.19.128/26203.78.19.129 to 203.78.19.190203.78.19.19162
80203.78.19.192/26203.78.19.193 to 203.78.19.254203.78.19.25562
81203.78.20.0/26203.78.20.1 to 203.78.20.62203.78.20.6362
82203.78.20.64/26203.78.20.65 to 203.78.20.126203.78.20.12762
83203.78.20.128/26203.78.20.129 to 203.78.20.190203.78.20.19162
84203.78.20.192/26203.78.20.193 to 203.78.20.254203.78.20.25562
85203.78.21.0/26203.78.21.1 to 203.78.21.62203.78.21.6362
86203.78.21.64/26203.78.21.65 to 203.78.21.126203.78.21.12762
87203.78.21.128/26203.78.21.129 to 203.78.21.190203.78.21.19162
88203.78.21.192/26203.78.21.193 to 203.78.21.254203.78.21.25562
89203.78.22.0/26203.78.22.1 to 203.78.22.62203.78.22.6362
90203.78.22.64/26203.78.22.65 to 203.78.22.126203.78.22.12762
91203.78.22.128/26203.78.22.129 to 203.78.22.190203.78.22.19162
92203.78.22.192/26203.78.22.193 to 203.78.22.254203.78.22.25562
93203.78.23.0/26203.78.23.1 to 203.78.23.62203.78.23.6362
94203.78.23.64/26203.78.23.65 to 203.78.23.126203.78.23.12762
95203.78.23.128/26203.78.23.129 to 203.78.23.190203.78.23.19162
96203.78.23.192/26203.78.23.193 to 203.78.23.254203.78.23.25562
97203.78.24.0/26203.78.24.1 to 203.78.24.62203.78.24.6362
98203.78.24.64/26203.78.24.65 to 203.78.24.126203.78.24.12762
99203.78.24.128/26203.78.24.129 to 203.78.24.190203.78.24.19162
100203.78.24.192/26203.78.24.193 to 203.78.24.254203.78.24.25562
101203.78.25.0/26203.78.25.1 to 203.78.25.62203.78.25.6362
102203.78.25.64/26203.78.25.65 to 203.78.25.126203.78.25.12762
103203.78.25.128/26203.78.25.129 to 203.78.25.190203.78.25.19162
104203.78.25.192/26203.78.25.193 to 203.78.25.254203.78.25.25562
105203.78.26.0/26203.78.26.1 to 203.78.26.62203.78.26.6362
106203.78.26.64/26203.78.26.65 to 203.78.26.126203.78.26.12762
107203.78.26.128/26203.78.26.129 to 203.78.26.190203.78.26.19162
108203.78.26.192/26203.78.26.193 to 203.78.26.254203.78.26.25562
109203.78.27.0/26203.78.27.1 to 203.78.27.62203.78.27.6362
110203.78.27.64/26203.78.27.65 to 203.78.27.126203.78.27.12762
111203.78.27.128/26203.78.27.129 to 203.78.27.190203.78.27.19162
112203.78.27.192/26203.78.27.193 to 203.78.27.254203.78.27.25562
113203.78.28.0/26203.78.28.1 to 203.78.28.62203.78.28.6362
114203.78.28.64/26203.78.28.65 to 203.78.28.126203.78.28.12762
115203.78.28.128/26203.78.28.129 to 203.78.28.190203.78.28.19162
116203.78.28.192/26203.78.28.193 to 203.78.28.254203.78.28.25562
117203.78.29.0/26203.78.29.1 to 203.78.29.62203.78.29.6362
118203.78.29.64/26203.78.29.65 to 203.78.29.126203.78.29.12762
119203.78.29.128/26203.78.29.129 to 203.78.29.190203.78.29.19162
120203.78.29.192/26203.78.29.193 to 203.78.29.254203.78.29.25562
121203.78.30.0/26203.78.30.1 to 203.78.30.62203.78.30.6362
122203.78.30.64/26203.78.30.65 to 203.78.30.126203.78.30.12762
123203.78.30.128/26203.78.30.129 to 203.78.30.190203.78.30.19162
124203.78.30.192/26203.78.30.193 to 203.78.30.254203.78.30.25562
125203.78.31.0/26203.78.31.1 to 203.78.31.62203.78.31.6362
126203.78.31.64/26203.78.31.65 to 203.78.31.126203.78.31.12762
127203.78.31.128/26203.78.31.129 to 203.78.31.190203.78.31.19162
128203.78.31.192/26203.78.31.193 to 203.78.31.254203.78.31.25562
129203.78.32.0/26203.78.32.1 to 203.78.32.62203.78.32.6362
130203.78.32.64/26203.78.32.65 to 203.78.32.126203.78.32.12762
131203.78.32.128/26203.78.32.129 to 203.78.32.190203.78.32.19162
132203.78.32.192/26203.78.32.193 to 203.78.32.254203.78.32.25562
133203.78.33.0/26203.78.33.1 to 203.78.33.62203.78.33.6362
134203.78.33.64/26203.78.33.65 to 203.78.33.126203.78.33.12762
135203.78.33.128/26203.78.33.129 to 203.78.33.190203.78.33.19162
136203.78.33.192/26203.78.33.193 to 203.78.33.254203.78.33.25562
137203.78.34.0/26203.78.34.1 to 203.78.34.62203.78.34.6362
138203.78.34.64/26203.78.34.65 to 203.78.34.126203.78.34.12762
139203.78.34.128/26203.78.34.129 to 203.78.34.190203.78.34.19162
140203.78.34.192/26203.78.34.193 to 203.78.34.254203.78.34.25562
141203.78.35.0/26203.78.35.1 to 203.78.35.62203.78.35.6362
142203.78.35.64/26203.78.35.65 to 203.78.35.126203.78.35.12762
143203.78.35.128/26203.78.35.129 to 203.78.35.190203.78.35.19162
144203.78.35.192/26203.78.35.193 to 203.78.35.254203.78.35.25562
145203.78.36.0/26203.78.36.1 to 203.78.36.62203.78.36.6362
146203.78.36.64/26203.78.36.65 to 203.78.36.126203.78.36.12762
147203.78.36.128/26203.78.36.129 to 203.78.36.190203.78.36.19162
148203.78.36.192/26203.78.36.193 to 203.78.36.254203.78.36.25562
149203.78.37.0/26203.78.37.1 to 203.78.37.62203.78.37.6362
150203.78.37.64/26203.78.37.65 to 203.78.37.126203.78.37.12762
151203.78.37.128/26203.78.37.129 to 203.78.37.190203.78.37.19162
152203.78.37.192/26203.78.37.193 to 203.78.37.254203.78.37.25562
153203.78.38.0/26203.78.38.1 to 203.78.38.62203.78.38.6362
154203.78.38.64/26203.78.38.65 to 203.78.38.126203.78.38.12762
155203.78.38.128/26203.78.38.129 to 203.78.38.190203.78.38.19162
156203.78.38.192/26203.78.38.193 to 203.78.38.254203.78.38.25562
157203.78.39.0/26203.78.39.1 to 203.78.39.62203.78.39.6362
158203.78.39.64/26203.78.39.65 to 203.78.39.126203.78.39.12762
159203.78.39.128/26203.78.39.129 to 203.78.39.190203.78.39.19162
160203.78.39.192/26203.78.39.193 to 203.78.39.254203.78.39.25562
161203.78.40.0/26203.78.40.1 to 203.78.40.62203.78.40.6362
162203.78.40.64/26203.78.40.65 to 203.78.40.126203.78.40.12762
163203.78.40.128/26203.78.40.129 to 203.78.40.190203.78.40.19162
164203.78.40.192/26203.78.40.193 to 203.78.40.254203.78.40.25562
165203.78.41.0/26203.78.41.1 to 203.78.41.62203.78.41.6362
166203.78.41.64/26203.78.41.65 to 203.78.41.126203.78.41.12762
167203.78.41.128/26203.78.41.129 to 203.78.41.190203.78.41.19162
168203.78.41.192/26203.78.41.193 to 203.78.41.254203.78.41.25562
169203.78.42.0/26203.78.42.1 to 203.78.42.62203.78.42.6362
170203.78.42.64/26203.78.42.65 to 203.78.42.126203.78.42.12762
171203.78.42.128/26203.78.42.129 to 203.78.42.190203.78.42.19162
172203.78.42.192/26203.78.42.193 to 203.78.42.254203.78.42.25562
173203.78.43.0/26203.78.43.1 to 203.78.43.62203.78.43.6362
174203.78.43.64/26203.78.43.65 to 203.78.43.126203.78.43.12762
175203.78.43.128/26203.78.43.129 to 203.78.43.190203.78.43.19162
176203.78.43.192/26203.78.43.193 to 203.78.43.254203.78.43.25562
177203.78.44.0/26203.78.44.1 to 203.78.44.62203.78.44.6362
178203.78.44.64/26203.78.44.65 to 203.78.44.126203.78.44.12762
179203.78.44.128/26203.78.44.129 to 203.78.44.190203.78.44.19162
180203.78.44.192/26203.78.44.193 to 203.78.44.254203.78.44.25562
181203.78.45.0/26203.78.45.1 to 203.78.45.62203.78.45.6362
182203.78.45.64/26203.78.45.65 to 203.78.45.126203.78.45.12762
183203.78.45.128/26203.78.45.129 to 203.78.45.190203.78.45.19162
184203.78.45.192/26203.78.45.193 to 203.78.45.254203.78.45.25562
185203.78.46.0/26203.78.46.1 to 203.78.46.62203.78.46.6362
186203.78.46.64/26203.78.46.65 to 203.78.46.126203.78.46.12762
187203.78.46.128/26203.78.46.129 to 203.78.46.190203.78.46.19162
188203.78.46.192/26203.78.46.193 to 203.78.46.254203.78.46.25562
189203.78.47.0/26203.78.47.1 to 203.78.47.62203.78.47.6362
190203.78.47.64/26203.78.47.65 to 203.78.47.126203.78.47.12762
191203.78.47.128/26203.78.47.129 to 203.78.47.190203.78.47.19162
192203.78.47.192/26203.78.47.193 to 203.78.47.254203.78.47.25562
193203.78.48.0/26203.78.48.1 to 203.78.48.62203.78.48.6362
194203.78.48.64/26203.78.48.65 to 203.78.48.126203.78.48.12762
195203.78.48.128/26203.78.48.129 to 203.78.48.190203.78.48.19162
196203.78.48.192/26203.78.48.193 to 203.78.48.254203.78.48.25562
197203.78.49.0/26203.78.49.1 to 203.78.49.62203.78.49.6362
198203.78.49.64/26203.78.49.65 to 203.78.49.126203.78.49.12762
199203.78.49.128/26203.78.49.129 to 203.78.49.190203.78.49.19162
200203.78.49.192/26203.78.49.193 to 203.78.49.254203.78.49.25562
201203.78.50.0/26203.78.50.1 to 203.78.50.62203.78.50.6362
202203.78.50.64/26203.78.50.65 to 203.78.50.126203.78.50.12762
203203.78.50.128/26203.78.50.129 to 203.78.50.190203.78.50.19162
204203.78.50.192/26203.78.50.193 to 203.78.50.254203.78.50.25562
205203.78.51.0/26203.78.51.1 to 203.78.51.62203.78.51.6362
206203.78.51.64/26203.78.51.65 to 203.78.51.126203.78.51.12762
207203.78.51.128/26203.78.51.129 to 203.78.51.190203.78.51.19162
208203.78.51.192/26203.78.51.193 to 203.78.51.254203.78.51.25562
209203.78.52.0/26203.78.52.1 to 203.78.52.62203.78.52.6362
210203.78.52.64/26203.78.52.65 to 203.78.52.126203.78.52.12762
211203.78.52.128/26203.78.52.129 to 203.78.52.190203.78.52.19162
212203.78.52.192/26203.78.52.193 to 203.78.52.254203.78.52.25562
213203.78.53.0/26203.78.53.1 to 203.78.53.62203.78.53.6362
214203.78.53.64/26203.78.53.65 to 203.78.53.126203.78.53.12762
215203.78.53.128/26203.78.53.129 to 203.78.53.190203.78.53.19162
216203.78.53.192/26203.78.53.193 to 203.78.53.254203.78.53.25562
217203.78.54.0/26203.78.54.1 to 203.78.54.62203.78.54.6362
218203.78.54.64/26203.78.54.65 to 203.78.54.126203.78.54.12762
219203.78.54.128/26203.78.54.129 to 203.78.54.190203.78.54.19162
220203.78.54.192/26203.78.54.193 to 203.78.54.254203.78.54.25562
221203.78.55.0/26203.78.55.1 to 203.78.55.62203.78.55.6362
222203.78.55.64/26203.78.55.65 to 203.78.55.126203.78.55.12762
223203.78.55.128/26203.78.55.129 to 203.78.55.190203.78.55.19162
224203.78.55.192/26203.78.55.193 to 203.78.55.254203.78.55.25562
225203.78.56.0/26203.78.56.1 to 203.78.56.62203.78.56.6362
226203.78.56.64/26203.78.56.65 to 203.78.56.126203.78.56.12762
227203.78.56.128/26203.78.56.129 to 203.78.56.190203.78.56.19162
228203.78.56.192/26203.78.56.193 to 203.78.56.254203.78.56.25562
229203.78.57.0/26203.78.57.1 to 203.78.57.62203.78.57.6362
230203.78.57.64/26203.78.57.65 to 203.78.57.126203.78.57.12762
231203.78.57.128/26203.78.57.129 to 203.78.57.190203.78.57.19162
232203.78.57.192/26203.78.57.193 to 203.78.57.254203.78.57.25562
233203.78.58.0/26203.78.58.1 to 203.78.58.62203.78.58.6362
234203.78.58.64/26203.78.58.65 to 203.78.58.126203.78.58.12762
235203.78.58.128/26203.78.58.129 to 203.78.58.190203.78.58.19162
236203.78.58.192/26203.78.58.193 to 203.78.58.254203.78.58.25562
237203.78.59.0/26203.78.59.1 to 203.78.59.62203.78.59.6362
238203.78.59.64/26203.78.59.65 to 203.78.59.126203.78.59.12762
239203.78.59.128/26203.78.59.129 to 203.78.59.190203.78.59.19162
240203.78.59.192/26203.78.59.193 to 203.78.59.254203.78.59.25562
241203.78.60.0/26203.78.60.1 to 203.78.60.62203.78.60.6362
242203.78.60.64/26203.78.60.65 to 203.78.60.126203.78.60.12762
243203.78.60.128/26203.78.60.129 to 203.78.60.190203.78.60.19162
244203.78.60.192/26203.78.60.193 to 203.78.60.254203.78.60.25562
245203.78.61.0/26203.78.61.1 to 203.78.61.62203.78.61.6362
246203.78.61.64/26203.78.61.65 to 203.78.61.126203.78.61.12762
247203.78.61.128/26203.78.61.129 to 203.78.61.190203.78.61.19162
248203.78.61.192/26203.78.61.193 to 203.78.61.254203.78.61.25562
249203.78.62.0/26203.78.62.1 to 203.78.62.62203.78.62.6362
250203.78.62.64/26203.78.62.65 to 203.78.62.126203.78.62.12762
251203.78.62.128/26203.78.62.129 to 203.78.62.190203.78.62.19162
252203.78.62.192/26203.78.62.193 to 203.78.62.254203.78.62.25562
253203.78.63.0/26203.78.63.1 to 203.78.63.62203.78.63.6362
254203.78.63.64/26203.78.63.65 to 203.78.63.126203.78.63.12762
255203.78.63.128/26203.78.63.129 to 203.78.63.190203.78.63.19162
256203.78.63.192/26203.78.63.193 to 203.78.63.254203.78.63.25562

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.