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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.

Network151.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
151.0.0.0
Broadcast address
151.255.255.255
First usable
151.0.0.1
Last usable
151.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex 97000000 · Integer 2533359616 to 2550136831
Reverse DNS zone
151.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010111..00000000.00000000.00000000151.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10010111..00000000.00000000.00000000151.0.0.0
Broadcast10010111..11111111.11111111.11111111151.255.255.255
Split into smaller subnets/18
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

151.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1151.0.0.0/18151.0.0.1 to 151.0.63.254151.0.63.25516,382
2151.0.64.0/18151.0.64.1 to 151.0.127.254151.0.127.25516,382
3151.0.128.0/18151.0.128.1 to 151.0.191.254151.0.191.25516,382
4151.0.192.0/18151.0.192.1 to 151.0.255.254151.0.255.25516,382
5151.1.0.0/18151.1.0.1 to 151.1.63.254151.1.63.25516,382
6151.1.64.0/18151.1.64.1 to 151.1.127.254151.1.127.25516,382
7151.1.128.0/18151.1.128.1 to 151.1.191.254151.1.191.25516,382
8151.1.192.0/18151.1.192.1 to 151.1.255.254151.1.255.25516,382
9151.2.0.0/18151.2.0.1 to 151.2.63.254151.2.63.25516,382
10151.2.64.0/18151.2.64.1 to 151.2.127.254151.2.127.25516,382
11151.2.128.0/18151.2.128.1 to 151.2.191.254151.2.191.25516,382
12151.2.192.0/18151.2.192.1 to 151.2.255.254151.2.255.25516,382
13151.3.0.0/18151.3.0.1 to 151.3.63.254151.3.63.25516,382
14151.3.64.0/18151.3.64.1 to 151.3.127.254151.3.127.25516,382
15151.3.128.0/18151.3.128.1 to 151.3.191.254151.3.191.25516,382
16151.3.192.0/18151.3.192.1 to 151.3.255.254151.3.255.25516,382
17151.4.0.0/18151.4.0.1 to 151.4.63.254151.4.63.25516,382
18151.4.64.0/18151.4.64.1 to 151.4.127.254151.4.127.25516,382
19151.4.128.0/18151.4.128.1 to 151.4.191.254151.4.191.25516,382
20151.4.192.0/18151.4.192.1 to 151.4.255.254151.4.255.25516,382
21151.5.0.0/18151.5.0.1 to 151.5.63.254151.5.63.25516,382
22151.5.64.0/18151.5.64.1 to 151.5.127.254151.5.127.25516,382
23151.5.128.0/18151.5.128.1 to 151.5.191.254151.5.191.25516,382
24151.5.192.0/18151.5.192.1 to 151.5.255.254151.5.255.25516,382
25151.6.0.0/18151.6.0.1 to 151.6.63.254151.6.63.25516,382
26151.6.64.0/18151.6.64.1 to 151.6.127.254151.6.127.25516,382
27151.6.128.0/18151.6.128.1 to 151.6.191.254151.6.191.25516,382
28151.6.192.0/18151.6.192.1 to 151.6.255.254151.6.255.25516,382
29151.7.0.0/18151.7.0.1 to 151.7.63.254151.7.63.25516,382
30151.7.64.0/18151.7.64.1 to 151.7.127.254151.7.127.25516,382
31151.7.128.0/18151.7.128.1 to 151.7.191.254151.7.191.25516,382
32151.7.192.0/18151.7.192.1 to 151.7.255.254151.7.255.25516,382
33151.8.0.0/18151.8.0.1 to 151.8.63.254151.8.63.25516,382
34151.8.64.0/18151.8.64.1 to 151.8.127.254151.8.127.25516,382
35151.8.128.0/18151.8.128.1 to 151.8.191.254151.8.191.25516,382
36151.8.192.0/18151.8.192.1 to 151.8.255.254151.8.255.25516,382
37151.9.0.0/18151.9.0.1 to 151.9.63.254151.9.63.25516,382
38151.9.64.0/18151.9.64.1 to 151.9.127.254151.9.127.25516,382
39151.9.128.0/18151.9.128.1 to 151.9.191.254151.9.191.25516,382
40151.9.192.0/18151.9.192.1 to 151.9.255.254151.9.255.25516,382
41151.10.0.0/18151.10.0.1 to 151.10.63.254151.10.63.25516,382
42151.10.64.0/18151.10.64.1 to 151.10.127.254151.10.127.25516,382
43151.10.128.0/18151.10.128.1 to 151.10.191.254151.10.191.25516,382
44151.10.192.0/18151.10.192.1 to 151.10.255.254151.10.255.25516,382
45151.11.0.0/18151.11.0.1 to 151.11.63.254151.11.63.25516,382
46151.11.64.0/18151.11.64.1 to 151.11.127.254151.11.127.25516,382
47151.11.128.0/18151.11.128.1 to 151.11.191.254151.11.191.25516,382
48151.11.192.0/18151.11.192.1 to 151.11.255.254151.11.255.25516,382
49151.12.0.0/18151.12.0.1 to 151.12.63.254151.12.63.25516,382
50151.12.64.0/18151.12.64.1 to 151.12.127.254151.12.127.25516,382
51151.12.128.0/18151.12.128.1 to 151.12.191.254151.12.191.25516,382
52151.12.192.0/18151.12.192.1 to 151.12.255.254151.12.255.25516,382
53151.13.0.0/18151.13.0.1 to 151.13.63.254151.13.63.25516,382
54151.13.64.0/18151.13.64.1 to 151.13.127.254151.13.127.25516,382
55151.13.128.0/18151.13.128.1 to 151.13.191.254151.13.191.25516,382
56151.13.192.0/18151.13.192.1 to 151.13.255.254151.13.255.25516,382
57151.14.0.0/18151.14.0.1 to 151.14.63.254151.14.63.25516,382
58151.14.64.0/18151.14.64.1 to 151.14.127.254151.14.127.25516,382
59151.14.128.0/18151.14.128.1 to 151.14.191.254151.14.191.25516,382
60151.14.192.0/18151.14.192.1 to 151.14.255.254151.14.255.25516,382
61151.15.0.0/18151.15.0.1 to 151.15.63.254151.15.63.25516,382
62151.15.64.0/18151.15.64.1 to 151.15.127.254151.15.127.25516,382
63151.15.128.0/18151.15.128.1 to 151.15.191.254151.15.191.25516,382
64151.15.192.0/18151.15.192.1 to 151.15.255.254151.15.255.25516,382
65151.16.0.0/18151.16.0.1 to 151.16.63.254151.16.63.25516,382
66151.16.64.0/18151.16.64.1 to 151.16.127.254151.16.127.25516,382
67151.16.128.0/18151.16.128.1 to 151.16.191.254151.16.191.25516,382
68151.16.192.0/18151.16.192.1 to 151.16.255.254151.16.255.25516,382
69151.17.0.0/18151.17.0.1 to 151.17.63.254151.17.63.25516,382
70151.17.64.0/18151.17.64.1 to 151.17.127.254151.17.127.25516,382
71151.17.128.0/18151.17.128.1 to 151.17.191.254151.17.191.25516,382
72151.17.192.0/18151.17.192.1 to 151.17.255.254151.17.255.25516,382
73151.18.0.0/18151.18.0.1 to 151.18.63.254151.18.63.25516,382
74151.18.64.0/18151.18.64.1 to 151.18.127.254151.18.127.25516,382
75151.18.128.0/18151.18.128.1 to 151.18.191.254151.18.191.25516,382
76151.18.192.0/18151.18.192.1 to 151.18.255.254151.18.255.25516,382
77151.19.0.0/18151.19.0.1 to 151.19.63.254151.19.63.25516,382
78151.19.64.0/18151.19.64.1 to 151.19.127.254151.19.127.25516,382
79151.19.128.0/18151.19.128.1 to 151.19.191.254151.19.191.25516,382
80151.19.192.0/18151.19.192.1 to 151.19.255.254151.19.255.25516,382
81151.20.0.0/18151.20.0.1 to 151.20.63.254151.20.63.25516,382
82151.20.64.0/18151.20.64.1 to 151.20.127.254151.20.127.25516,382
83151.20.128.0/18151.20.128.1 to 151.20.191.254151.20.191.25516,382
84151.20.192.0/18151.20.192.1 to 151.20.255.254151.20.255.25516,382
85151.21.0.0/18151.21.0.1 to 151.21.63.254151.21.63.25516,382
86151.21.64.0/18151.21.64.1 to 151.21.127.254151.21.127.25516,382
87151.21.128.0/18151.21.128.1 to 151.21.191.254151.21.191.25516,382
88151.21.192.0/18151.21.192.1 to 151.21.255.254151.21.255.25516,382
89151.22.0.0/18151.22.0.1 to 151.22.63.254151.22.63.25516,382
90151.22.64.0/18151.22.64.1 to 151.22.127.254151.22.127.25516,382
91151.22.128.0/18151.22.128.1 to 151.22.191.254151.22.191.25516,382
92151.22.192.0/18151.22.192.1 to 151.22.255.254151.22.255.25516,382
93151.23.0.0/18151.23.0.1 to 151.23.63.254151.23.63.25516,382
94151.23.64.0/18151.23.64.1 to 151.23.127.254151.23.127.25516,382
95151.23.128.0/18151.23.128.1 to 151.23.191.254151.23.191.25516,382
96151.23.192.0/18151.23.192.1 to 151.23.255.254151.23.255.25516,382
97151.24.0.0/18151.24.0.1 to 151.24.63.254151.24.63.25516,382
98151.24.64.0/18151.24.64.1 to 151.24.127.254151.24.127.25516,382
99151.24.128.0/18151.24.128.1 to 151.24.191.254151.24.191.25516,382
100151.24.192.0/18151.24.192.1 to 151.24.255.254151.24.255.25516,382
101151.25.0.0/18151.25.0.1 to 151.25.63.254151.25.63.25516,382
102151.25.64.0/18151.25.64.1 to 151.25.127.254151.25.127.25516,382
103151.25.128.0/18151.25.128.1 to 151.25.191.254151.25.191.25516,382
104151.25.192.0/18151.25.192.1 to 151.25.255.254151.25.255.25516,382
105151.26.0.0/18151.26.0.1 to 151.26.63.254151.26.63.25516,382
106151.26.64.0/18151.26.64.1 to 151.26.127.254151.26.127.25516,382
107151.26.128.0/18151.26.128.1 to 151.26.191.254151.26.191.25516,382
108151.26.192.0/18151.26.192.1 to 151.26.255.254151.26.255.25516,382
109151.27.0.0/18151.27.0.1 to 151.27.63.254151.27.63.25516,382
110151.27.64.0/18151.27.64.1 to 151.27.127.254151.27.127.25516,382
111151.27.128.0/18151.27.128.1 to 151.27.191.254151.27.191.25516,382
112151.27.192.0/18151.27.192.1 to 151.27.255.254151.27.255.25516,382
113151.28.0.0/18151.28.0.1 to 151.28.63.254151.28.63.25516,382
114151.28.64.0/18151.28.64.1 to 151.28.127.254151.28.127.25516,382
115151.28.128.0/18151.28.128.1 to 151.28.191.254151.28.191.25516,382
116151.28.192.0/18151.28.192.1 to 151.28.255.254151.28.255.25516,382
117151.29.0.0/18151.29.0.1 to 151.29.63.254151.29.63.25516,382
118151.29.64.0/18151.29.64.1 to 151.29.127.254151.29.127.25516,382
119151.29.128.0/18151.29.128.1 to 151.29.191.254151.29.191.25516,382
120151.29.192.0/18151.29.192.1 to 151.29.255.254151.29.255.25516,382
121151.30.0.0/18151.30.0.1 to 151.30.63.254151.30.63.25516,382
122151.30.64.0/18151.30.64.1 to 151.30.127.254151.30.127.25516,382
123151.30.128.0/18151.30.128.1 to 151.30.191.254151.30.191.25516,382
124151.30.192.0/18151.30.192.1 to 151.30.255.254151.30.255.25516,382
125151.31.0.0/18151.31.0.1 to 151.31.63.254151.31.63.25516,382
126151.31.64.0/18151.31.64.1 to 151.31.127.254151.31.127.25516,382
127151.31.128.0/18151.31.128.1 to 151.31.191.254151.31.191.25516,382
128151.31.192.0/18151.31.192.1 to 151.31.255.254151.31.255.25516,382
129151.32.0.0/18151.32.0.1 to 151.32.63.254151.32.63.25516,382
130151.32.64.0/18151.32.64.1 to 151.32.127.254151.32.127.25516,382
131151.32.128.0/18151.32.128.1 to 151.32.191.254151.32.191.25516,382
132151.32.192.0/18151.32.192.1 to 151.32.255.254151.32.255.25516,382
133151.33.0.0/18151.33.0.1 to 151.33.63.254151.33.63.25516,382
134151.33.64.0/18151.33.64.1 to 151.33.127.254151.33.127.25516,382
135151.33.128.0/18151.33.128.1 to 151.33.191.254151.33.191.25516,382
136151.33.192.0/18151.33.192.1 to 151.33.255.254151.33.255.25516,382
137151.34.0.0/18151.34.0.1 to 151.34.63.254151.34.63.25516,382
138151.34.64.0/18151.34.64.1 to 151.34.127.254151.34.127.25516,382
139151.34.128.0/18151.34.128.1 to 151.34.191.254151.34.191.25516,382
140151.34.192.0/18151.34.192.1 to 151.34.255.254151.34.255.25516,382
141151.35.0.0/18151.35.0.1 to 151.35.63.254151.35.63.25516,382
142151.35.64.0/18151.35.64.1 to 151.35.127.254151.35.127.25516,382
143151.35.128.0/18151.35.128.1 to 151.35.191.254151.35.191.25516,382
144151.35.192.0/18151.35.192.1 to 151.35.255.254151.35.255.25516,382
145151.36.0.0/18151.36.0.1 to 151.36.63.254151.36.63.25516,382
146151.36.64.0/18151.36.64.1 to 151.36.127.254151.36.127.25516,382
147151.36.128.0/18151.36.128.1 to 151.36.191.254151.36.191.25516,382
148151.36.192.0/18151.36.192.1 to 151.36.255.254151.36.255.25516,382
149151.37.0.0/18151.37.0.1 to 151.37.63.254151.37.63.25516,382
150151.37.64.0/18151.37.64.1 to 151.37.127.254151.37.127.25516,382
151151.37.128.0/18151.37.128.1 to 151.37.191.254151.37.191.25516,382
152151.37.192.0/18151.37.192.1 to 151.37.255.254151.37.255.25516,382
153151.38.0.0/18151.38.0.1 to 151.38.63.254151.38.63.25516,382
154151.38.64.0/18151.38.64.1 to 151.38.127.254151.38.127.25516,382
155151.38.128.0/18151.38.128.1 to 151.38.191.254151.38.191.25516,382
156151.38.192.0/18151.38.192.1 to 151.38.255.254151.38.255.25516,382
157151.39.0.0/18151.39.0.1 to 151.39.63.254151.39.63.25516,382
158151.39.64.0/18151.39.64.1 to 151.39.127.254151.39.127.25516,382
159151.39.128.0/18151.39.128.1 to 151.39.191.254151.39.191.25516,382
160151.39.192.0/18151.39.192.1 to 151.39.255.254151.39.255.25516,382
161151.40.0.0/18151.40.0.1 to 151.40.63.254151.40.63.25516,382
162151.40.64.0/18151.40.64.1 to 151.40.127.254151.40.127.25516,382
163151.40.128.0/18151.40.128.1 to 151.40.191.254151.40.191.25516,382
164151.40.192.0/18151.40.192.1 to 151.40.255.254151.40.255.25516,382
165151.41.0.0/18151.41.0.1 to 151.41.63.254151.41.63.25516,382
166151.41.64.0/18151.41.64.1 to 151.41.127.254151.41.127.25516,382
167151.41.128.0/18151.41.128.1 to 151.41.191.254151.41.191.25516,382
168151.41.192.0/18151.41.192.1 to 151.41.255.254151.41.255.25516,382
169151.42.0.0/18151.42.0.1 to 151.42.63.254151.42.63.25516,382
170151.42.64.0/18151.42.64.1 to 151.42.127.254151.42.127.25516,382
171151.42.128.0/18151.42.128.1 to 151.42.191.254151.42.191.25516,382
172151.42.192.0/18151.42.192.1 to 151.42.255.254151.42.255.25516,382
173151.43.0.0/18151.43.0.1 to 151.43.63.254151.43.63.25516,382
174151.43.64.0/18151.43.64.1 to 151.43.127.254151.43.127.25516,382
175151.43.128.0/18151.43.128.1 to 151.43.191.254151.43.191.25516,382
176151.43.192.0/18151.43.192.1 to 151.43.255.254151.43.255.25516,382
177151.44.0.0/18151.44.0.1 to 151.44.63.254151.44.63.25516,382
178151.44.64.0/18151.44.64.1 to 151.44.127.254151.44.127.25516,382
179151.44.128.0/18151.44.128.1 to 151.44.191.254151.44.191.25516,382
180151.44.192.0/18151.44.192.1 to 151.44.255.254151.44.255.25516,382
181151.45.0.0/18151.45.0.1 to 151.45.63.254151.45.63.25516,382
182151.45.64.0/18151.45.64.1 to 151.45.127.254151.45.127.25516,382
183151.45.128.0/18151.45.128.1 to 151.45.191.254151.45.191.25516,382
184151.45.192.0/18151.45.192.1 to 151.45.255.254151.45.255.25516,382
185151.46.0.0/18151.46.0.1 to 151.46.63.254151.46.63.25516,382
186151.46.64.0/18151.46.64.1 to 151.46.127.254151.46.127.25516,382
187151.46.128.0/18151.46.128.1 to 151.46.191.254151.46.191.25516,382
188151.46.192.0/18151.46.192.1 to 151.46.255.254151.46.255.25516,382
189151.47.0.0/18151.47.0.1 to 151.47.63.254151.47.63.25516,382
190151.47.64.0/18151.47.64.1 to 151.47.127.254151.47.127.25516,382
191151.47.128.0/18151.47.128.1 to 151.47.191.254151.47.191.25516,382
192151.47.192.0/18151.47.192.1 to 151.47.255.254151.47.255.25516,382
193151.48.0.0/18151.48.0.1 to 151.48.63.254151.48.63.25516,382
194151.48.64.0/18151.48.64.1 to 151.48.127.254151.48.127.25516,382
195151.48.128.0/18151.48.128.1 to 151.48.191.254151.48.191.25516,382
196151.48.192.0/18151.48.192.1 to 151.48.255.254151.48.255.25516,382
197151.49.0.0/18151.49.0.1 to 151.49.63.254151.49.63.25516,382
198151.49.64.0/18151.49.64.1 to 151.49.127.254151.49.127.25516,382
199151.49.128.0/18151.49.128.1 to 151.49.191.254151.49.191.25516,382
200151.49.192.0/18151.49.192.1 to 151.49.255.254151.49.255.25516,382
201151.50.0.0/18151.50.0.1 to 151.50.63.254151.50.63.25516,382
202151.50.64.0/18151.50.64.1 to 151.50.127.254151.50.127.25516,382
203151.50.128.0/18151.50.128.1 to 151.50.191.254151.50.191.25516,382
204151.50.192.0/18151.50.192.1 to 151.50.255.254151.50.255.25516,382
205151.51.0.0/18151.51.0.1 to 151.51.63.254151.51.63.25516,382
206151.51.64.0/18151.51.64.1 to 151.51.127.254151.51.127.25516,382
207151.51.128.0/18151.51.128.1 to 151.51.191.254151.51.191.25516,382
208151.51.192.0/18151.51.192.1 to 151.51.255.254151.51.255.25516,382
209151.52.0.0/18151.52.0.1 to 151.52.63.254151.52.63.25516,382
210151.52.64.0/18151.52.64.1 to 151.52.127.254151.52.127.25516,382
211151.52.128.0/18151.52.128.1 to 151.52.191.254151.52.191.25516,382
212151.52.192.0/18151.52.192.1 to 151.52.255.254151.52.255.25516,382
213151.53.0.0/18151.53.0.1 to 151.53.63.254151.53.63.25516,382
214151.53.64.0/18151.53.64.1 to 151.53.127.254151.53.127.25516,382
215151.53.128.0/18151.53.128.1 to 151.53.191.254151.53.191.25516,382
216151.53.192.0/18151.53.192.1 to 151.53.255.254151.53.255.25516,382
217151.54.0.0/18151.54.0.1 to 151.54.63.254151.54.63.25516,382
218151.54.64.0/18151.54.64.1 to 151.54.127.254151.54.127.25516,382
219151.54.128.0/18151.54.128.1 to 151.54.191.254151.54.191.25516,382
220151.54.192.0/18151.54.192.1 to 151.54.255.254151.54.255.25516,382
221151.55.0.0/18151.55.0.1 to 151.55.63.254151.55.63.25516,382
222151.55.64.0/18151.55.64.1 to 151.55.127.254151.55.127.25516,382
223151.55.128.0/18151.55.128.1 to 151.55.191.254151.55.191.25516,382
224151.55.192.0/18151.55.192.1 to 151.55.255.254151.55.255.25516,382
225151.56.0.0/18151.56.0.1 to 151.56.63.254151.56.63.25516,382
226151.56.64.0/18151.56.64.1 to 151.56.127.254151.56.127.25516,382
227151.56.128.0/18151.56.128.1 to 151.56.191.254151.56.191.25516,382
228151.56.192.0/18151.56.192.1 to 151.56.255.254151.56.255.25516,382
229151.57.0.0/18151.57.0.1 to 151.57.63.254151.57.63.25516,382
230151.57.64.0/18151.57.64.1 to 151.57.127.254151.57.127.25516,382
231151.57.128.0/18151.57.128.1 to 151.57.191.254151.57.191.25516,382
232151.57.192.0/18151.57.192.1 to 151.57.255.254151.57.255.25516,382
233151.58.0.0/18151.58.0.1 to 151.58.63.254151.58.63.25516,382
234151.58.64.0/18151.58.64.1 to 151.58.127.254151.58.127.25516,382
235151.58.128.0/18151.58.128.1 to 151.58.191.254151.58.191.25516,382
236151.58.192.0/18151.58.192.1 to 151.58.255.254151.58.255.25516,382
237151.59.0.0/18151.59.0.1 to 151.59.63.254151.59.63.25516,382
238151.59.64.0/18151.59.64.1 to 151.59.127.254151.59.127.25516,382
239151.59.128.0/18151.59.128.1 to 151.59.191.254151.59.191.25516,382
240151.59.192.0/18151.59.192.1 to 151.59.255.254151.59.255.25516,382
241151.60.0.0/18151.60.0.1 to 151.60.63.254151.60.63.25516,382
242151.60.64.0/18151.60.64.1 to 151.60.127.254151.60.127.25516,382
243151.60.128.0/18151.60.128.1 to 151.60.191.254151.60.191.25516,382
244151.60.192.0/18151.60.192.1 to 151.60.255.254151.60.255.25516,382
245151.61.0.0/18151.61.0.1 to 151.61.63.254151.61.63.25516,382
246151.61.64.0/18151.61.64.1 to 151.61.127.254151.61.127.25516,382
247151.61.128.0/18151.61.128.1 to 151.61.191.254151.61.191.25516,382
248151.61.192.0/18151.61.192.1 to 151.61.255.254151.61.255.25516,382
249151.62.0.0/18151.62.0.1 to 151.62.63.254151.62.63.25516,382
250151.62.64.0/18151.62.64.1 to 151.62.127.254151.62.127.25516,382
251151.62.128.0/18151.62.128.1 to 151.62.191.254151.62.191.25516,382
252151.62.192.0/18151.62.192.1 to 151.62.255.254151.62.255.25516,382
253151.63.0.0/18151.63.0.1 to 151.63.63.254151.63.63.25516,382
254151.63.64.0/18151.63.64.1 to 151.63.127.254151.63.127.25516,382
255151.63.128.0/18151.63.128.1 to 151.63.191.254151.63.191.25516,382
256151.63.192.0/18151.63.192.1 to 151.63.255.254151.63.255.25516,382

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.