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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/19
/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 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1151.0.0.0/19151.0.0.1 to 151.0.31.254151.0.31.2558,190
2151.0.32.0/19151.0.32.1 to 151.0.63.254151.0.63.2558,190
3151.0.64.0/19151.0.64.1 to 151.0.95.254151.0.95.2558,190
4151.0.96.0/19151.0.96.1 to 151.0.127.254151.0.127.2558,190
5151.0.128.0/19151.0.128.1 to 151.0.159.254151.0.159.2558,190
6151.0.160.0/19151.0.160.1 to 151.0.191.254151.0.191.2558,190
7151.0.192.0/19151.0.192.1 to 151.0.223.254151.0.223.2558,190
8151.0.224.0/19151.0.224.1 to 151.0.255.254151.0.255.2558,190
9151.1.0.0/19151.1.0.1 to 151.1.31.254151.1.31.2558,190
10151.1.32.0/19151.1.32.1 to 151.1.63.254151.1.63.2558,190
11151.1.64.0/19151.1.64.1 to 151.1.95.254151.1.95.2558,190
12151.1.96.0/19151.1.96.1 to 151.1.127.254151.1.127.2558,190
13151.1.128.0/19151.1.128.1 to 151.1.159.254151.1.159.2558,190
14151.1.160.0/19151.1.160.1 to 151.1.191.254151.1.191.2558,190
15151.1.192.0/19151.1.192.1 to 151.1.223.254151.1.223.2558,190
16151.1.224.0/19151.1.224.1 to 151.1.255.254151.1.255.2558,190
17151.2.0.0/19151.2.0.1 to 151.2.31.254151.2.31.2558,190
18151.2.32.0/19151.2.32.1 to 151.2.63.254151.2.63.2558,190
19151.2.64.0/19151.2.64.1 to 151.2.95.254151.2.95.2558,190
20151.2.96.0/19151.2.96.1 to 151.2.127.254151.2.127.2558,190
21151.2.128.0/19151.2.128.1 to 151.2.159.254151.2.159.2558,190
22151.2.160.0/19151.2.160.1 to 151.2.191.254151.2.191.2558,190
23151.2.192.0/19151.2.192.1 to 151.2.223.254151.2.223.2558,190
24151.2.224.0/19151.2.224.1 to 151.2.255.254151.2.255.2558,190
25151.3.0.0/19151.3.0.1 to 151.3.31.254151.3.31.2558,190
26151.3.32.0/19151.3.32.1 to 151.3.63.254151.3.63.2558,190
27151.3.64.0/19151.3.64.1 to 151.3.95.254151.3.95.2558,190
28151.3.96.0/19151.3.96.1 to 151.3.127.254151.3.127.2558,190
29151.3.128.0/19151.3.128.1 to 151.3.159.254151.3.159.2558,190
30151.3.160.0/19151.3.160.1 to 151.3.191.254151.3.191.2558,190
31151.3.192.0/19151.3.192.1 to 151.3.223.254151.3.223.2558,190
32151.3.224.0/19151.3.224.1 to 151.3.255.254151.3.255.2558,190
33151.4.0.0/19151.4.0.1 to 151.4.31.254151.4.31.2558,190
34151.4.32.0/19151.4.32.1 to 151.4.63.254151.4.63.2558,190
35151.4.64.0/19151.4.64.1 to 151.4.95.254151.4.95.2558,190
36151.4.96.0/19151.4.96.1 to 151.4.127.254151.4.127.2558,190
37151.4.128.0/19151.4.128.1 to 151.4.159.254151.4.159.2558,190
38151.4.160.0/19151.4.160.1 to 151.4.191.254151.4.191.2558,190
39151.4.192.0/19151.4.192.1 to 151.4.223.254151.4.223.2558,190
40151.4.224.0/19151.4.224.1 to 151.4.255.254151.4.255.2558,190
41151.5.0.0/19151.5.0.1 to 151.5.31.254151.5.31.2558,190
42151.5.32.0/19151.5.32.1 to 151.5.63.254151.5.63.2558,190
43151.5.64.0/19151.5.64.1 to 151.5.95.254151.5.95.2558,190
44151.5.96.0/19151.5.96.1 to 151.5.127.254151.5.127.2558,190
45151.5.128.0/19151.5.128.1 to 151.5.159.254151.5.159.2558,190
46151.5.160.0/19151.5.160.1 to 151.5.191.254151.5.191.2558,190
47151.5.192.0/19151.5.192.1 to 151.5.223.254151.5.223.2558,190
48151.5.224.0/19151.5.224.1 to 151.5.255.254151.5.255.2558,190
49151.6.0.0/19151.6.0.1 to 151.6.31.254151.6.31.2558,190
50151.6.32.0/19151.6.32.1 to 151.6.63.254151.6.63.2558,190
51151.6.64.0/19151.6.64.1 to 151.6.95.254151.6.95.2558,190
52151.6.96.0/19151.6.96.1 to 151.6.127.254151.6.127.2558,190
53151.6.128.0/19151.6.128.1 to 151.6.159.254151.6.159.2558,190
54151.6.160.0/19151.6.160.1 to 151.6.191.254151.6.191.2558,190
55151.6.192.0/19151.6.192.1 to 151.6.223.254151.6.223.2558,190
56151.6.224.0/19151.6.224.1 to 151.6.255.254151.6.255.2558,190
57151.7.0.0/19151.7.0.1 to 151.7.31.254151.7.31.2558,190
58151.7.32.0/19151.7.32.1 to 151.7.63.254151.7.63.2558,190
59151.7.64.0/19151.7.64.1 to 151.7.95.254151.7.95.2558,190
60151.7.96.0/19151.7.96.1 to 151.7.127.254151.7.127.2558,190
61151.7.128.0/19151.7.128.1 to 151.7.159.254151.7.159.2558,190
62151.7.160.0/19151.7.160.1 to 151.7.191.254151.7.191.2558,190
63151.7.192.0/19151.7.192.1 to 151.7.223.254151.7.223.2558,190
64151.7.224.0/19151.7.224.1 to 151.7.255.254151.7.255.2558,190
65151.8.0.0/19151.8.0.1 to 151.8.31.254151.8.31.2558,190
66151.8.32.0/19151.8.32.1 to 151.8.63.254151.8.63.2558,190
67151.8.64.0/19151.8.64.1 to 151.8.95.254151.8.95.2558,190
68151.8.96.0/19151.8.96.1 to 151.8.127.254151.8.127.2558,190
69151.8.128.0/19151.8.128.1 to 151.8.159.254151.8.159.2558,190
70151.8.160.0/19151.8.160.1 to 151.8.191.254151.8.191.2558,190
71151.8.192.0/19151.8.192.1 to 151.8.223.254151.8.223.2558,190
72151.8.224.0/19151.8.224.1 to 151.8.255.254151.8.255.2558,190
73151.9.0.0/19151.9.0.1 to 151.9.31.254151.9.31.2558,190
74151.9.32.0/19151.9.32.1 to 151.9.63.254151.9.63.2558,190
75151.9.64.0/19151.9.64.1 to 151.9.95.254151.9.95.2558,190
76151.9.96.0/19151.9.96.1 to 151.9.127.254151.9.127.2558,190
77151.9.128.0/19151.9.128.1 to 151.9.159.254151.9.159.2558,190
78151.9.160.0/19151.9.160.1 to 151.9.191.254151.9.191.2558,190
79151.9.192.0/19151.9.192.1 to 151.9.223.254151.9.223.2558,190
80151.9.224.0/19151.9.224.1 to 151.9.255.254151.9.255.2558,190
81151.10.0.0/19151.10.0.1 to 151.10.31.254151.10.31.2558,190
82151.10.32.0/19151.10.32.1 to 151.10.63.254151.10.63.2558,190
83151.10.64.0/19151.10.64.1 to 151.10.95.254151.10.95.2558,190
84151.10.96.0/19151.10.96.1 to 151.10.127.254151.10.127.2558,190
85151.10.128.0/19151.10.128.1 to 151.10.159.254151.10.159.2558,190
86151.10.160.0/19151.10.160.1 to 151.10.191.254151.10.191.2558,190
87151.10.192.0/19151.10.192.1 to 151.10.223.254151.10.223.2558,190
88151.10.224.0/19151.10.224.1 to 151.10.255.254151.10.255.2558,190
89151.11.0.0/19151.11.0.1 to 151.11.31.254151.11.31.2558,190
90151.11.32.0/19151.11.32.1 to 151.11.63.254151.11.63.2558,190
91151.11.64.0/19151.11.64.1 to 151.11.95.254151.11.95.2558,190
92151.11.96.0/19151.11.96.1 to 151.11.127.254151.11.127.2558,190
93151.11.128.0/19151.11.128.1 to 151.11.159.254151.11.159.2558,190
94151.11.160.0/19151.11.160.1 to 151.11.191.254151.11.191.2558,190
95151.11.192.0/19151.11.192.1 to 151.11.223.254151.11.223.2558,190
96151.11.224.0/19151.11.224.1 to 151.11.255.254151.11.255.2558,190
97151.12.0.0/19151.12.0.1 to 151.12.31.254151.12.31.2558,190
98151.12.32.0/19151.12.32.1 to 151.12.63.254151.12.63.2558,190
99151.12.64.0/19151.12.64.1 to 151.12.95.254151.12.95.2558,190
100151.12.96.0/19151.12.96.1 to 151.12.127.254151.12.127.2558,190
101151.12.128.0/19151.12.128.1 to 151.12.159.254151.12.159.2558,190
102151.12.160.0/19151.12.160.1 to 151.12.191.254151.12.191.2558,190
103151.12.192.0/19151.12.192.1 to 151.12.223.254151.12.223.2558,190
104151.12.224.0/19151.12.224.1 to 151.12.255.254151.12.255.2558,190
105151.13.0.0/19151.13.0.1 to 151.13.31.254151.13.31.2558,190
106151.13.32.0/19151.13.32.1 to 151.13.63.254151.13.63.2558,190
107151.13.64.0/19151.13.64.1 to 151.13.95.254151.13.95.2558,190
108151.13.96.0/19151.13.96.1 to 151.13.127.254151.13.127.2558,190
109151.13.128.0/19151.13.128.1 to 151.13.159.254151.13.159.2558,190
110151.13.160.0/19151.13.160.1 to 151.13.191.254151.13.191.2558,190
111151.13.192.0/19151.13.192.1 to 151.13.223.254151.13.223.2558,190
112151.13.224.0/19151.13.224.1 to 151.13.255.254151.13.255.2558,190
113151.14.0.0/19151.14.0.1 to 151.14.31.254151.14.31.2558,190
114151.14.32.0/19151.14.32.1 to 151.14.63.254151.14.63.2558,190
115151.14.64.0/19151.14.64.1 to 151.14.95.254151.14.95.2558,190
116151.14.96.0/19151.14.96.1 to 151.14.127.254151.14.127.2558,190
117151.14.128.0/19151.14.128.1 to 151.14.159.254151.14.159.2558,190
118151.14.160.0/19151.14.160.1 to 151.14.191.254151.14.191.2558,190
119151.14.192.0/19151.14.192.1 to 151.14.223.254151.14.223.2558,190
120151.14.224.0/19151.14.224.1 to 151.14.255.254151.14.255.2558,190
121151.15.0.0/19151.15.0.1 to 151.15.31.254151.15.31.2558,190
122151.15.32.0/19151.15.32.1 to 151.15.63.254151.15.63.2558,190
123151.15.64.0/19151.15.64.1 to 151.15.95.254151.15.95.2558,190
124151.15.96.0/19151.15.96.1 to 151.15.127.254151.15.127.2558,190
125151.15.128.0/19151.15.128.1 to 151.15.159.254151.15.159.2558,190
126151.15.160.0/19151.15.160.1 to 151.15.191.254151.15.191.2558,190
127151.15.192.0/19151.15.192.1 to 151.15.223.254151.15.223.2558,190
128151.15.224.0/19151.15.224.1 to 151.15.255.254151.15.255.2558,190
129151.16.0.0/19151.16.0.1 to 151.16.31.254151.16.31.2558,190
130151.16.32.0/19151.16.32.1 to 151.16.63.254151.16.63.2558,190
131151.16.64.0/19151.16.64.1 to 151.16.95.254151.16.95.2558,190
132151.16.96.0/19151.16.96.1 to 151.16.127.254151.16.127.2558,190
133151.16.128.0/19151.16.128.1 to 151.16.159.254151.16.159.2558,190
134151.16.160.0/19151.16.160.1 to 151.16.191.254151.16.191.2558,190
135151.16.192.0/19151.16.192.1 to 151.16.223.254151.16.223.2558,190
136151.16.224.0/19151.16.224.1 to 151.16.255.254151.16.255.2558,190
137151.17.0.0/19151.17.0.1 to 151.17.31.254151.17.31.2558,190
138151.17.32.0/19151.17.32.1 to 151.17.63.254151.17.63.2558,190
139151.17.64.0/19151.17.64.1 to 151.17.95.254151.17.95.2558,190
140151.17.96.0/19151.17.96.1 to 151.17.127.254151.17.127.2558,190
141151.17.128.0/19151.17.128.1 to 151.17.159.254151.17.159.2558,190
142151.17.160.0/19151.17.160.1 to 151.17.191.254151.17.191.2558,190
143151.17.192.0/19151.17.192.1 to 151.17.223.254151.17.223.2558,190
144151.17.224.0/19151.17.224.1 to 151.17.255.254151.17.255.2558,190
145151.18.0.0/19151.18.0.1 to 151.18.31.254151.18.31.2558,190
146151.18.32.0/19151.18.32.1 to 151.18.63.254151.18.63.2558,190
147151.18.64.0/19151.18.64.1 to 151.18.95.254151.18.95.2558,190
148151.18.96.0/19151.18.96.1 to 151.18.127.254151.18.127.2558,190
149151.18.128.0/19151.18.128.1 to 151.18.159.254151.18.159.2558,190
150151.18.160.0/19151.18.160.1 to 151.18.191.254151.18.191.2558,190
151151.18.192.0/19151.18.192.1 to 151.18.223.254151.18.223.2558,190
152151.18.224.0/19151.18.224.1 to 151.18.255.254151.18.255.2558,190
153151.19.0.0/19151.19.0.1 to 151.19.31.254151.19.31.2558,190
154151.19.32.0/19151.19.32.1 to 151.19.63.254151.19.63.2558,190
155151.19.64.0/19151.19.64.1 to 151.19.95.254151.19.95.2558,190
156151.19.96.0/19151.19.96.1 to 151.19.127.254151.19.127.2558,190
157151.19.128.0/19151.19.128.1 to 151.19.159.254151.19.159.2558,190
158151.19.160.0/19151.19.160.1 to 151.19.191.254151.19.191.2558,190
159151.19.192.0/19151.19.192.1 to 151.19.223.254151.19.223.2558,190
160151.19.224.0/19151.19.224.1 to 151.19.255.254151.19.255.2558,190
161151.20.0.0/19151.20.0.1 to 151.20.31.254151.20.31.2558,190
162151.20.32.0/19151.20.32.1 to 151.20.63.254151.20.63.2558,190
163151.20.64.0/19151.20.64.1 to 151.20.95.254151.20.95.2558,190
164151.20.96.0/19151.20.96.1 to 151.20.127.254151.20.127.2558,190
165151.20.128.0/19151.20.128.1 to 151.20.159.254151.20.159.2558,190
166151.20.160.0/19151.20.160.1 to 151.20.191.254151.20.191.2558,190
167151.20.192.0/19151.20.192.1 to 151.20.223.254151.20.223.2558,190
168151.20.224.0/19151.20.224.1 to 151.20.255.254151.20.255.2558,190
169151.21.0.0/19151.21.0.1 to 151.21.31.254151.21.31.2558,190
170151.21.32.0/19151.21.32.1 to 151.21.63.254151.21.63.2558,190
171151.21.64.0/19151.21.64.1 to 151.21.95.254151.21.95.2558,190
172151.21.96.0/19151.21.96.1 to 151.21.127.254151.21.127.2558,190
173151.21.128.0/19151.21.128.1 to 151.21.159.254151.21.159.2558,190
174151.21.160.0/19151.21.160.1 to 151.21.191.254151.21.191.2558,190
175151.21.192.0/19151.21.192.1 to 151.21.223.254151.21.223.2558,190
176151.21.224.0/19151.21.224.1 to 151.21.255.254151.21.255.2558,190
177151.22.0.0/19151.22.0.1 to 151.22.31.254151.22.31.2558,190
178151.22.32.0/19151.22.32.1 to 151.22.63.254151.22.63.2558,190
179151.22.64.0/19151.22.64.1 to 151.22.95.254151.22.95.2558,190
180151.22.96.0/19151.22.96.1 to 151.22.127.254151.22.127.2558,190
181151.22.128.0/19151.22.128.1 to 151.22.159.254151.22.159.2558,190
182151.22.160.0/19151.22.160.1 to 151.22.191.254151.22.191.2558,190
183151.22.192.0/19151.22.192.1 to 151.22.223.254151.22.223.2558,190
184151.22.224.0/19151.22.224.1 to 151.22.255.254151.22.255.2558,190
185151.23.0.0/19151.23.0.1 to 151.23.31.254151.23.31.2558,190
186151.23.32.0/19151.23.32.1 to 151.23.63.254151.23.63.2558,190
187151.23.64.0/19151.23.64.1 to 151.23.95.254151.23.95.2558,190
188151.23.96.0/19151.23.96.1 to 151.23.127.254151.23.127.2558,190
189151.23.128.0/19151.23.128.1 to 151.23.159.254151.23.159.2558,190
190151.23.160.0/19151.23.160.1 to 151.23.191.254151.23.191.2558,190
191151.23.192.0/19151.23.192.1 to 151.23.223.254151.23.223.2558,190
192151.23.224.0/19151.23.224.1 to 151.23.255.254151.23.255.2558,190
193151.24.0.0/19151.24.0.1 to 151.24.31.254151.24.31.2558,190
194151.24.32.0/19151.24.32.1 to 151.24.63.254151.24.63.2558,190
195151.24.64.0/19151.24.64.1 to 151.24.95.254151.24.95.2558,190
196151.24.96.0/19151.24.96.1 to 151.24.127.254151.24.127.2558,190
197151.24.128.0/19151.24.128.1 to 151.24.159.254151.24.159.2558,190
198151.24.160.0/19151.24.160.1 to 151.24.191.254151.24.191.2558,190
199151.24.192.0/19151.24.192.1 to 151.24.223.254151.24.223.2558,190
200151.24.224.0/19151.24.224.1 to 151.24.255.254151.24.255.2558,190
201151.25.0.0/19151.25.0.1 to 151.25.31.254151.25.31.2558,190
202151.25.32.0/19151.25.32.1 to 151.25.63.254151.25.63.2558,190
203151.25.64.0/19151.25.64.1 to 151.25.95.254151.25.95.2558,190
204151.25.96.0/19151.25.96.1 to 151.25.127.254151.25.127.2558,190
205151.25.128.0/19151.25.128.1 to 151.25.159.254151.25.159.2558,190
206151.25.160.0/19151.25.160.1 to 151.25.191.254151.25.191.2558,190
207151.25.192.0/19151.25.192.1 to 151.25.223.254151.25.223.2558,190
208151.25.224.0/19151.25.224.1 to 151.25.255.254151.25.255.2558,190
209151.26.0.0/19151.26.0.1 to 151.26.31.254151.26.31.2558,190
210151.26.32.0/19151.26.32.1 to 151.26.63.254151.26.63.2558,190
211151.26.64.0/19151.26.64.1 to 151.26.95.254151.26.95.2558,190
212151.26.96.0/19151.26.96.1 to 151.26.127.254151.26.127.2558,190
213151.26.128.0/19151.26.128.1 to 151.26.159.254151.26.159.2558,190
214151.26.160.0/19151.26.160.1 to 151.26.191.254151.26.191.2558,190
215151.26.192.0/19151.26.192.1 to 151.26.223.254151.26.223.2558,190
216151.26.224.0/19151.26.224.1 to 151.26.255.254151.26.255.2558,190
217151.27.0.0/19151.27.0.1 to 151.27.31.254151.27.31.2558,190
218151.27.32.0/19151.27.32.1 to 151.27.63.254151.27.63.2558,190
219151.27.64.0/19151.27.64.1 to 151.27.95.254151.27.95.2558,190
220151.27.96.0/19151.27.96.1 to 151.27.127.254151.27.127.2558,190
221151.27.128.0/19151.27.128.1 to 151.27.159.254151.27.159.2558,190
222151.27.160.0/19151.27.160.1 to 151.27.191.254151.27.191.2558,190
223151.27.192.0/19151.27.192.1 to 151.27.223.254151.27.223.2558,190
224151.27.224.0/19151.27.224.1 to 151.27.255.254151.27.255.2558,190
225151.28.0.0/19151.28.0.1 to 151.28.31.254151.28.31.2558,190
226151.28.32.0/19151.28.32.1 to 151.28.63.254151.28.63.2558,190
227151.28.64.0/19151.28.64.1 to 151.28.95.254151.28.95.2558,190
228151.28.96.0/19151.28.96.1 to 151.28.127.254151.28.127.2558,190
229151.28.128.0/19151.28.128.1 to 151.28.159.254151.28.159.2558,190
230151.28.160.0/19151.28.160.1 to 151.28.191.254151.28.191.2558,190
231151.28.192.0/19151.28.192.1 to 151.28.223.254151.28.223.2558,190
232151.28.224.0/19151.28.224.1 to 151.28.255.254151.28.255.2558,190
233151.29.0.0/19151.29.0.1 to 151.29.31.254151.29.31.2558,190
234151.29.32.0/19151.29.32.1 to 151.29.63.254151.29.63.2558,190
235151.29.64.0/19151.29.64.1 to 151.29.95.254151.29.95.2558,190
236151.29.96.0/19151.29.96.1 to 151.29.127.254151.29.127.2558,190
237151.29.128.0/19151.29.128.1 to 151.29.159.254151.29.159.2558,190
238151.29.160.0/19151.29.160.1 to 151.29.191.254151.29.191.2558,190
239151.29.192.0/19151.29.192.1 to 151.29.223.254151.29.223.2558,190
240151.29.224.0/19151.29.224.1 to 151.29.255.254151.29.255.2558,190
241151.30.0.0/19151.30.0.1 to 151.30.31.254151.30.31.2558,190
242151.30.32.0/19151.30.32.1 to 151.30.63.254151.30.63.2558,190
243151.30.64.0/19151.30.64.1 to 151.30.95.254151.30.95.2558,190
244151.30.96.0/19151.30.96.1 to 151.30.127.254151.30.127.2558,190
245151.30.128.0/19151.30.128.1 to 151.30.159.254151.30.159.2558,190
246151.30.160.0/19151.30.160.1 to 151.30.191.254151.30.191.2558,190
247151.30.192.0/19151.30.192.1 to 151.30.223.254151.30.223.2558,190
248151.30.224.0/19151.30.224.1 to 151.30.255.254151.30.255.2558,190
249151.31.0.0/19151.31.0.1 to 151.31.31.254151.31.31.2558,190
250151.31.32.0/19151.31.32.1 to 151.31.63.254151.31.63.2558,190
251151.31.64.0/19151.31.64.1 to 151.31.95.254151.31.95.2558,190
252151.31.96.0/19151.31.96.1 to 151.31.127.254151.31.127.2558,190
253151.31.128.0/19151.31.128.1 to 151.31.159.254151.31.159.2558,190
254151.31.160.0/19151.31.160.1 to 151.31.191.254151.31.191.2558,190
255151.31.192.0/19151.31.192.1 to 151.31.223.254151.31.223.2558,190
256151.31.224.0/19151.31.224.1 to 151.31.255.254151.31.255.2558,190

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.