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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.

Network245.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
245.0.0.0
Broadcast address
245.63.255.255
First usable
245.0.0.1
Last usable
245.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F5000000 · Integer 4110417920 to 4114612223
Reverse DNS zones
0.245.in-addr.arpa
1.245.in-addr.arpa
2.245.in-addr.arpa
3.245.in-addr.arpa
4.245.in-addr.arpa
5.245.in-addr.arpa
6.245.in-addr.arpa
7.245.in-addr.arpa
8.245.in-addr.arpa
9.245.in-addr.arpa
10.245.in-addr.arpa
11.245.in-addr.arpa
12.245.in-addr.arpa
13.245.in-addr.arpa
14.245.in-addr.arpa
15.245.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110101.00000000.00000000.00000000245.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11110101.00000000.00000000.00000000245.0.0.0
Broadcast11110101.00111111.11111111.11111111245.63.255.255
Split into smaller subnets/18
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

245.0.0.0/10 makes 256 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1245.0.0.0/18245.0.0.1 to 245.0.63.254245.0.63.25516,382
2245.0.64.0/18245.0.64.1 to 245.0.127.254245.0.127.25516,382
3245.0.128.0/18245.0.128.1 to 245.0.191.254245.0.191.25516,382
4245.0.192.0/18245.0.192.1 to 245.0.255.254245.0.255.25516,382
5245.1.0.0/18245.1.0.1 to 245.1.63.254245.1.63.25516,382
6245.1.64.0/18245.1.64.1 to 245.1.127.254245.1.127.25516,382
7245.1.128.0/18245.1.128.1 to 245.1.191.254245.1.191.25516,382
8245.1.192.0/18245.1.192.1 to 245.1.255.254245.1.255.25516,382
9245.2.0.0/18245.2.0.1 to 245.2.63.254245.2.63.25516,382
10245.2.64.0/18245.2.64.1 to 245.2.127.254245.2.127.25516,382
11245.2.128.0/18245.2.128.1 to 245.2.191.254245.2.191.25516,382
12245.2.192.0/18245.2.192.1 to 245.2.255.254245.2.255.25516,382
13245.3.0.0/18245.3.0.1 to 245.3.63.254245.3.63.25516,382
14245.3.64.0/18245.3.64.1 to 245.3.127.254245.3.127.25516,382
15245.3.128.0/18245.3.128.1 to 245.3.191.254245.3.191.25516,382
16245.3.192.0/18245.3.192.1 to 245.3.255.254245.3.255.25516,382
17245.4.0.0/18245.4.0.1 to 245.4.63.254245.4.63.25516,382
18245.4.64.0/18245.4.64.1 to 245.4.127.254245.4.127.25516,382
19245.4.128.0/18245.4.128.1 to 245.4.191.254245.4.191.25516,382
20245.4.192.0/18245.4.192.1 to 245.4.255.254245.4.255.25516,382
21245.5.0.0/18245.5.0.1 to 245.5.63.254245.5.63.25516,382
22245.5.64.0/18245.5.64.1 to 245.5.127.254245.5.127.25516,382
23245.5.128.0/18245.5.128.1 to 245.5.191.254245.5.191.25516,382
24245.5.192.0/18245.5.192.1 to 245.5.255.254245.5.255.25516,382
25245.6.0.0/18245.6.0.1 to 245.6.63.254245.6.63.25516,382
26245.6.64.0/18245.6.64.1 to 245.6.127.254245.6.127.25516,382
27245.6.128.0/18245.6.128.1 to 245.6.191.254245.6.191.25516,382
28245.6.192.0/18245.6.192.1 to 245.6.255.254245.6.255.25516,382
29245.7.0.0/18245.7.0.1 to 245.7.63.254245.7.63.25516,382
30245.7.64.0/18245.7.64.1 to 245.7.127.254245.7.127.25516,382
31245.7.128.0/18245.7.128.1 to 245.7.191.254245.7.191.25516,382
32245.7.192.0/18245.7.192.1 to 245.7.255.254245.7.255.25516,382
33245.8.0.0/18245.8.0.1 to 245.8.63.254245.8.63.25516,382
34245.8.64.0/18245.8.64.1 to 245.8.127.254245.8.127.25516,382
35245.8.128.0/18245.8.128.1 to 245.8.191.254245.8.191.25516,382
36245.8.192.0/18245.8.192.1 to 245.8.255.254245.8.255.25516,382
37245.9.0.0/18245.9.0.1 to 245.9.63.254245.9.63.25516,382
38245.9.64.0/18245.9.64.1 to 245.9.127.254245.9.127.25516,382
39245.9.128.0/18245.9.128.1 to 245.9.191.254245.9.191.25516,382
40245.9.192.0/18245.9.192.1 to 245.9.255.254245.9.255.25516,382
41245.10.0.0/18245.10.0.1 to 245.10.63.254245.10.63.25516,382
42245.10.64.0/18245.10.64.1 to 245.10.127.254245.10.127.25516,382
43245.10.128.0/18245.10.128.1 to 245.10.191.254245.10.191.25516,382
44245.10.192.0/18245.10.192.1 to 245.10.255.254245.10.255.25516,382
45245.11.0.0/18245.11.0.1 to 245.11.63.254245.11.63.25516,382
46245.11.64.0/18245.11.64.1 to 245.11.127.254245.11.127.25516,382
47245.11.128.0/18245.11.128.1 to 245.11.191.254245.11.191.25516,382
48245.11.192.0/18245.11.192.1 to 245.11.255.254245.11.255.25516,382
49245.12.0.0/18245.12.0.1 to 245.12.63.254245.12.63.25516,382
50245.12.64.0/18245.12.64.1 to 245.12.127.254245.12.127.25516,382
51245.12.128.0/18245.12.128.1 to 245.12.191.254245.12.191.25516,382
52245.12.192.0/18245.12.192.1 to 245.12.255.254245.12.255.25516,382
53245.13.0.0/18245.13.0.1 to 245.13.63.254245.13.63.25516,382
54245.13.64.0/18245.13.64.1 to 245.13.127.254245.13.127.25516,382
55245.13.128.0/18245.13.128.1 to 245.13.191.254245.13.191.25516,382
56245.13.192.0/18245.13.192.1 to 245.13.255.254245.13.255.25516,382
57245.14.0.0/18245.14.0.1 to 245.14.63.254245.14.63.25516,382
58245.14.64.0/18245.14.64.1 to 245.14.127.254245.14.127.25516,382
59245.14.128.0/18245.14.128.1 to 245.14.191.254245.14.191.25516,382
60245.14.192.0/18245.14.192.1 to 245.14.255.254245.14.255.25516,382
61245.15.0.0/18245.15.0.1 to 245.15.63.254245.15.63.25516,382
62245.15.64.0/18245.15.64.1 to 245.15.127.254245.15.127.25516,382
63245.15.128.0/18245.15.128.1 to 245.15.191.254245.15.191.25516,382
64245.15.192.0/18245.15.192.1 to 245.15.255.254245.15.255.25516,382
65245.16.0.0/18245.16.0.1 to 245.16.63.254245.16.63.25516,382
66245.16.64.0/18245.16.64.1 to 245.16.127.254245.16.127.25516,382
67245.16.128.0/18245.16.128.1 to 245.16.191.254245.16.191.25516,382
68245.16.192.0/18245.16.192.1 to 245.16.255.254245.16.255.25516,382
69245.17.0.0/18245.17.0.1 to 245.17.63.254245.17.63.25516,382
70245.17.64.0/18245.17.64.1 to 245.17.127.254245.17.127.25516,382
71245.17.128.0/18245.17.128.1 to 245.17.191.254245.17.191.25516,382
72245.17.192.0/18245.17.192.1 to 245.17.255.254245.17.255.25516,382
73245.18.0.0/18245.18.0.1 to 245.18.63.254245.18.63.25516,382
74245.18.64.0/18245.18.64.1 to 245.18.127.254245.18.127.25516,382
75245.18.128.0/18245.18.128.1 to 245.18.191.254245.18.191.25516,382
76245.18.192.0/18245.18.192.1 to 245.18.255.254245.18.255.25516,382
77245.19.0.0/18245.19.0.1 to 245.19.63.254245.19.63.25516,382
78245.19.64.0/18245.19.64.1 to 245.19.127.254245.19.127.25516,382
79245.19.128.0/18245.19.128.1 to 245.19.191.254245.19.191.25516,382
80245.19.192.0/18245.19.192.1 to 245.19.255.254245.19.255.25516,382
81245.20.0.0/18245.20.0.1 to 245.20.63.254245.20.63.25516,382
82245.20.64.0/18245.20.64.1 to 245.20.127.254245.20.127.25516,382
83245.20.128.0/18245.20.128.1 to 245.20.191.254245.20.191.25516,382
84245.20.192.0/18245.20.192.1 to 245.20.255.254245.20.255.25516,382
85245.21.0.0/18245.21.0.1 to 245.21.63.254245.21.63.25516,382
86245.21.64.0/18245.21.64.1 to 245.21.127.254245.21.127.25516,382
87245.21.128.0/18245.21.128.1 to 245.21.191.254245.21.191.25516,382
88245.21.192.0/18245.21.192.1 to 245.21.255.254245.21.255.25516,382
89245.22.0.0/18245.22.0.1 to 245.22.63.254245.22.63.25516,382
90245.22.64.0/18245.22.64.1 to 245.22.127.254245.22.127.25516,382
91245.22.128.0/18245.22.128.1 to 245.22.191.254245.22.191.25516,382
92245.22.192.0/18245.22.192.1 to 245.22.255.254245.22.255.25516,382
93245.23.0.0/18245.23.0.1 to 245.23.63.254245.23.63.25516,382
94245.23.64.0/18245.23.64.1 to 245.23.127.254245.23.127.25516,382
95245.23.128.0/18245.23.128.1 to 245.23.191.254245.23.191.25516,382
96245.23.192.0/18245.23.192.1 to 245.23.255.254245.23.255.25516,382
97245.24.0.0/18245.24.0.1 to 245.24.63.254245.24.63.25516,382
98245.24.64.0/18245.24.64.1 to 245.24.127.254245.24.127.25516,382
99245.24.128.0/18245.24.128.1 to 245.24.191.254245.24.191.25516,382
100245.24.192.0/18245.24.192.1 to 245.24.255.254245.24.255.25516,382
101245.25.0.0/18245.25.0.1 to 245.25.63.254245.25.63.25516,382
102245.25.64.0/18245.25.64.1 to 245.25.127.254245.25.127.25516,382
103245.25.128.0/18245.25.128.1 to 245.25.191.254245.25.191.25516,382
104245.25.192.0/18245.25.192.1 to 245.25.255.254245.25.255.25516,382
105245.26.0.0/18245.26.0.1 to 245.26.63.254245.26.63.25516,382
106245.26.64.0/18245.26.64.1 to 245.26.127.254245.26.127.25516,382
107245.26.128.0/18245.26.128.1 to 245.26.191.254245.26.191.25516,382
108245.26.192.0/18245.26.192.1 to 245.26.255.254245.26.255.25516,382
109245.27.0.0/18245.27.0.1 to 245.27.63.254245.27.63.25516,382
110245.27.64.0/18245.27.64.1 to 245.27.127.254245.27.127.25516,382
111245.27.128.0/18245.27.128.1 to 245.27.191.254245.27.191.25516,382
112245.27.192.0/18245.27.192.1 to 245.27.255.254245.27.255.25516,382
113245.28.0.0/18245.28.0.1 to 245.28.63.254245.28.63.25516,382
114245.28.64.0/18245.28.64.1 to 245.28.127.254245.28.127.25516,382
115245.28.128.0/18245.28.128.1 to 245.28.191.254245.28.191.25516,382
116245.28.192.0/18245.28.192.1 to 245.28.255.254245.28.255.25516,382
117245.29.0.0/18245.29.0.1 to 245.29.63.254245.29.63.25516,382
118245.29.64.0/18245.29.64.1 to 245.29.127.254245.29.127.25516,382
119245.29.128.0/18245.29.128.1 to 245.29.191.254245.29.191.25516,382
120245.29.192.0/18245.29.192.1 to 245.29.255.254245.29.255.25516,382
121245.30.0.0/18245.30.0.1 to 245.30.63.254245.30.63.25516,382
122245.30.64.0/18245.30.64.1 to 245.30.127.254245.30.127.25516,382
123245.30.128.0/18245.30.128.1 to 245.30.191.254245.30.191.25516,382
124245.30.192.0/18245.30.192.1 to 245.30.255.254245.30.255.25516,382
125245.31.0.0/18245.31.0.1 to 245.31.63.254245.31.63.25516,382
126245.31.64.0/18245.31.64.1 to 245.31.127.254245.31.127.25516,382
127245.31.128.0/18245.31.128.1 to 245.31.191.254245.31.191.25516,382
128245.31.192.0/18245.31.192.1 to 245.31.255.254245.31.255.25516,382
129245.32.0.0/18245.32.0.1 to 245.32.63.254245.32.63.25516,382
130245.32.64.0/18245.32.64.1 to 245.32.127.254245.32.127.25516,382
131245.32.128.0/18245.32.128.1 to 245.32.191.254245.32.191.25516,382
132245.32.192.0/18245.32.192.1 to 245.32.255.254245.32.255.25516,382
133245.33.0.0/18245.33.0.1 to 245.33.63.254245.33.63.25516,382
134245.33.64.0/18245.33.64.1 to 245.33.127.254245.33.127.25516,382
135245.33.128.0/18245.33.128.1 to 245.33.191.254245.33.191.25516,382
136245.33.192.0/18245.33.192.1 to 245.33.255.254245.33.255.25516,382
137245.34.0.0/18245.34.0.1 to 245.34.63.254245.34.63.25516,382
138245.34.64.0/18245.34.64.1 to 245.34.127.254245.34.127.25516,382
139245.34.128.0/18245.34.128.1 to 245.34.191.254245.34.191.25516,382
140245.34.192.0/18245.34.192.1 to 245.34.255.254245.34.255.25516,382
141245.35.0.0/18245.35.0.1 to 245.35.63.254245.35.63.25516,382
142245.35.64.0/18245.35.64.1 to 245.35.127.254245.35.127.25516,382
143245.35.128.0/18245.35.128.1 to 245.35.191.254245.35.191.25516,382
144245.35.192.0/18245.35.192.1 to 245.35.255.254245.35.255.25516,382
145245.36.0.0/18245.36.0.1 to 245.36.63.254245.36.63.25516,382
146245.36.64.0/18245.36.64.1 to 245.36.127.254245.36.127.25516,382
147245.36.128.0/18245.36.128.1 to 245.36.191.254245.36.191.25516,382
148245.36.192.0/18245.36.192.1 to 245.36.255.254245.36.255.25516,382
149245.37.0.0/18245.37.0.1 to 245.37.63.254245.37.63.25516,382
150245.37.64.0/18245.37.64.1 to 245.37.127.254245.37.127.25516,382
151245.37.128.0/18245.37.128.1 to 245.37.191.254245.37.191.25516,382
152245.37.192.0/18245.37.192.1 to 245.37.255.254245.37.255.25516,382
153245.38.0.0/18245.38.0.1 to 245.38.63.254245.38.63.25516,382
154245.38.64.0/18245.38.64.1 to 245.38.127.254245.38.127.25516,382
155245.38.128.0/18245.38.128.1 to 245.38.191.254245.38.191.25516,382
156245.38.192.0/18245.38.192.1 to 245.38.255.254245.38.255.25516,382
157245.39.0.0/18245.39.0.1 to 245.39.63.254245.39.63.25516,382
158245.39.64.0/18245.39.64.1 to 245.39.127.254245.39.127.25516,382
159245.39.128.0/18245.39.128.1 to 245.39.191.254245.39.191.25516,382
160245.39.192.0/18245.39.192.1 to 245.39.255.254245.39.255.25516,382
161245.40.0.0/18245.40.0.1 to 245.40.63.254245.40.63.25516,382
162245.40.64.0/18245.40.64.1 to 245.40.127.254245.40.127.25516,382
163245.40.128.0/18245.40.128.1 to 245.40.191.254245.40.191.25516,382
164245.40.192.0/18245.40.192.1 to 245.40.255.254245.40.255.25516,382
165245.41.0.0/18245.41.0.1 to 245.41.63.254245.41.63.25516,382
166245.41.64.0/18245.41.64.1 to 245.41.127.254245.41.127.25516,382
167245.41.128.0/18245.41.128.1 to 245.41.191.254245.41.191.25516,382
168245.41.192.0/18245.41.192.1 to 245.41.255.254245.41.255.25516,382
169245.42.0.0/18245.42.0.1 to 245.42.63.254245.42.63.25516,382
170245.42.64.0/18245.42.64.1 to 245.42.127.254245.42.127.25516,382
171245.42.128.0/18245.42.128.1 to 245.42.191.254245.42.191.25516,382
172245.42.192.0/18245.42.192.1 to 245.42.255.254245.42.255.25516,382
173245.43.0.0/18245.43.0.1 to 245.43.63.254245.43.63.25516,382
174245.43.64.0/18245.43.64.1 to 245.43.127.254245.43.127.25516,382
175245.43.128.0/18245.43.128.1 to 245.43.191.254245.43.191.25516,382
176245.43.192.0/18245.43.192.1 to 245.43.255.254245.43.255.25516,382
177245.44.0.0/18245.44.0.1 to 245.44.63.254245.44.63.25516,382
178245.44.64.0/18245.44.64.1 to 245.44.127.254245.44.127.25516,382
179245.44.128.0/18245.44.128.1 to 245.44.191.254245.44.191.25516,382
180245.44.192.0/18245.44.192.1 to 245.44.255.254245.44.255.25516,382
181245.45.0.0/18245.45.0.1 to 245.45.63.254245.45.63.25516,382
182245.45.64.0/18245.45.64.1 to 245.45.127.254245.45.127.25516,382
183245.45.128.0/18245.45.128.1 to 245.45.191.254245.45.191.25516,382
184245.45.192.0/18245.45.192.1 to 245.45.255.254245.45.255.25516,382
185245.46.0.0/18245.46.0.1 to 245.46.63.254245.46.63.25516,382
186245.46.64.0/18245.46.64.1 to 245.46.127.254245.46.127.25516,382
187245.46.128.0/18245.46.128.1 to 245.46.191.254245.46.191.25516,382
188245.46.192.0/18245.46.192.1 to 245.46.255.254245.46.255.25516,382
189245.47.0.0/18245.47.0.1 to 245.47.63.254245.47.63.25516,382
190245.47.64.0/18245.47.64.1 to 245.47.127.254245.47.127.25516,382
191245.47.128.0/18245.47.128.1 to 245.47.191.254245.47.191.25516,382
192245.47.192.0/18245.47.192.1 to 245.47.255.254245.47.255.25516,382
193245.48.0.0/18245.48.0.1 to 245.48.63.254245.48.63.25516,382
194245.48.64.0/18245.48.64.1 to 245.48.127.254245.48.127.25516,382
195245.48.128.0/18245.48.128.1 to 245.48.191.254245.48.191.25516,382
196245.48.192.0/18245.48.192.1 to 245.48.255.254245.48.255.25516,382
197245.49.0.0/18245.49.0.1 to 245.49.63.254245.49.63.25516,382
198245.49.64.0/18245.49.64.1 to 245.49.127.254245.49.127.25516,382
199245.49.128.0/18245.49.128.1 to 245.49.191.254245.49.191.25516,382
200245.49.192.0/18245.49.192.1 to 245.49.255.254245.49.255.25516,382
201245.50.0.0/18245.50.0.1 to 245.50.63.254245.50.63.25516,382
202245.50.64.0/18245.50.64.1 to 245.50.127.254245.50.127.25516,382
203245.50.128.0/18245.50.128.1 to 245.50.191.254245.50.191.25516,382
204245.50.192.0/18245.50.192.1 to 245.50.255.254245.50.255.25516,382
205245.51.0.0/18245.51.0.1 to 245.51.63.254245.51.63.25516,382
206245.51.64.0/18245.51.64.1 to 245.51.127.254245.51.127.25516,382
207245.51.128.0/18245.51.128.1 to 245.51.191.254245.51.191.25516,382
208245.51.192.0/18245.51.192.1 to 245.51.255.254245.51.255.25516,382
209245.52.0.0/18245.52.0.1 to 245.52.63.254245.52.63.25516,382
210245.52.64.0/18245.52.64.1 to 245.52.127.254245.52.127.25516,382
211245.52.128.0/18245.52.128.1 to 245.52.191.254245.52.191.25516,382
212245.52.192.0/18245.52.192.1 to 245.52.255.254245.52.255.25516,382
213245.53.0.0/18245.53.0.1 to 245.53.63.254245.53.63.25516,382
214245.53.64.0/18245.53.64.1 to 245.53.127.254245.53.127.25516,382
215245.53.128.0/18245.53.128.1 to 245.53.191.254245.53.191.25516,382
216245.53.192.0/18245.53.192.1 to 245.53.255.254245.53.255.25516,382
217245.54.0.0/18245.54.0.1 to 245.54.63.254245.54.63.25516,382
218245.54.64.0/18245.54.64.1 to 245.54.127.254245.54.127.25516,382
219245.54.128.0/18245.54.128.1 to 245.54.191.254245.54.191.25516,382
220245.54.192.0/18245.54.192.1 to 245.54.255.254245.54.255.25516,382
221245.55.0.0/18245.55.0.1 to 245.55.63.254245.55.63.25516,382
222245.55.64.0/18245.55.64.1 to 245.55.127.254245.55.127.25516,382
223245.55.128.0/18245.55.128.1 to 245.55.191.254245.55.191.25516,382
224245.55.192.0/18245.55.192.1 to 245.55.255.254245.55.255.25516,382
225245.56.0.0/18245.56.0.1 to 245.56.63.254245.56.63.25516,382
226245.56.64.0/18245.56.64.1 to 245.56.127.254245.56.127.25516,382
227245.56.128.0/18245.56.128.1 to 245.56.191.254245.56.191.25516,382
228245.56.192.0/18245.56.192.1 to 245.56.255.254245.56.255.25516,382
229245.57.0.0/18245.57.0.1 to 245.57.63.254245.57.63.25516,382
230245.57.64.0/18245.57.64.1 to 245.57.127.254245.57.127.25516,382
231245.57.128.0/18245.57.128.1 to 245.57.191.254245.57.191.25516,382
232245.57.192.0/18245.57.192.1 to 245.57.255.254245.57.255.25516,382
233245.58.0.0/18245.58.0.1 to 245.58.63.254245.58.63.25516,382
234245.58.64.0/18245.58.64.1 to 245.58.127.254245.58.127.25516,382
235245.58.128.0/18245.58.128.1 to 245.58.191.254245.58.191.25516,382
236245.58.192.0/18245.58.192.1 to 245.58.255.254245.58.255.25516,382
237245.59.0.0/18245.59.0.1 to 245.59.63.254245.59.63.25516,382
238245.59.64.0/18245.59.64.1 to 245.59.127.254245.59.127.25516,382
239245.59.128.0/18245.59.128.1 to 245.59.191.254245.59.191.25516,382
240245.59.192.0/18245.59.192.1 to 245.59.255.254245.59.255.25516,382
241245.60.0.0/18245.60.0.1 to 245.60.63.254245.60.63.25516,382
242245.60.64.0/18245.60.64.1 to 245.60.127.254245.60.127.25516,382
243245.60.128.0/18245.60.128.1 to 245.60.191.254245.60.191.25516,382
244245.60.192.0/18245.60.192.1 to 245.60.255.254245.60.255.25516,382
245245.61.0.0/18245.61.0.1 to 245.61.63.254245.61.63.25516,382
246245.61.64.0/18245.61.64.1 to 245.61.127.254245.61.127.25516,382
247245.61.128.0/18245.61.128.1 to 245.61.191.254245.61.191.25516,382
248245.61.192.0/18245.61.192.1 to 245.61.255.254245.61.255.25516,382
249245.62.0.0/18245.62.0.1 to 245.62.63.254245.62.63.25516,382
250245.62.64.0/18245.62.64.1 to 245.62.127.254245.62.127.25516,382
251245.62.128.0/18245.62.128.1 to 245.62.191.254245.62.191.25516,382
252245.62.192.0/18245.62.192.1 to 245.62.255.254245.62.255.25516,382
253245.63.0.0/18245.63.0.1 to 245.63.63.254245.63.63.25516,382
254245.63.64.0/18245.63.64.1 to 245.63.127.254245.63.127.25516,382
255245.63.128.0/18245.63.128.1 to 245.63.191.254245.63.191.25516,382
256245.63.192.0/18245.63.192.1 to 245.63.255.254245.63.255.25516,382

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.