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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/20
/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 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1151.0.0.0/20151.0.0.1 to 151.0.15.254151.0.15.2554,094
2151.0.16.0/20151.0.16.1 to 151.0.31.254151.0.31.2554,094
3151.0.32.0/20151.0.32.1 to 151.0.47.254151.0.47.2554,094
4151.0.48.0/20151.0.48.1 to 151.0.63.254151.0.63.2554,094
5151.0.64.0/20151.0.64.1 to 151.0.79.254151.0.79.2554,094
6151.0.80.0/20151.0.80.1 to 151.0.95.254151.0.95.2554,094
7151.0.96.0/20151.0.96.1 to 151.0.111.254151.0.111.2554,094
8151.0.112.0/20151.0.112.1 to 151.0.127.254151.0.127.2554,094
9151.0.128.0/20151.0.128.1 to 151.0.143.254151.0.143.2554,094
10151.0.144.0/20151.0.144.1 to 151.0.159.254151.0.159.2554,094
11151.0.160.0/20151.0.160.1 to 151.0.175.254151.0.175.2554,094
12151.0.176.0/20151.0.176.1 to 151.0.191.254151.0.191.2554,094
13151.0.192.0/20151.0.192.1 to 151.0.207.254151.0.207.2554,094
14151.0.208.0/20151.0.208.1 to 151.0.223.254151.0.223.2554,094
15151.0.224.0/20151.0.224.1 to 151.0.239.254151.0.239.2554,094
16151.0.240.0/20151.0.240.1 to 151.0.255.254151.0.255.2554,094
17151.1.0.0/20151.1.0.1 to 151.1.15.254151.1.15.2554,094
18151.1.16.0/20151.1.16.1 to 151.1.31.254151.1.31.2554,094
19151.1.32.0/20151.1.32.1 to 151.1.47.254151.1.47.2554,094
20151.1.48.0/20151.1.48.1 to 151.1.63.254151.1.63.2554,094
21151.1.64.0/20151.1.64.1 to 151.1.79.254151.1.79.2554,094
22151.1.80.0/20151.1.80.1 to 151.1.95.254151.1.95.2554,094
23151.1.96.0/20151.1.96.1 to 151.1.111.254151.1.111.2554,094
24151.1.112.0/20151.1.112.1 to 151.1.127.254151.1.127.2554,094
25151.1.128.0/20151.1.128.1 to 151.1.143.254151.1.143.2554,094
26151.1.144.0/20151.1.144.1 to 151.1.159.254151.1.159.2554,094
27151.1.160.0/20151.1.160.1 to 151.1.175.254151.1.175.2554,094
28151.1.176.0/20151.1.176.1 to 151.1.191.254151.1.191.2554,094
29151.1.192.0/20151.1.192.1 to 151.1.207.254151.1.207.2554,094
30151.1.208.0/20151.1.208.1 to 151.1.223.254151.1.223.2554,094
31151.1.224.0/20151.1.224.1 to 151.1.239.254151.1.239.2554,094
32151.1.240.0/20151.1.240.1 to 151.1.255.254151.1.255.2554,094
33151.2.0.0/20151.2.0.1 to 151.2.15.254151.2.15.2554,094
34151.2.16.0/20151.2.16.1 to 151.2.31.254151.2.31.2554,094
35151.2.32.0/20151.2.32.1 to 151.2.47.254151.2.47.2554,094
36151.2.48.0/20151.2.48.1 to 151.2.63.254151.2.63.2554,094
37151.2.64.0/20151.2.64.1 to 151.2.79.254151.2.79.2554,094
38151.2.80.0/20151.2.80.1 to 151.2.95.254151.2.95.2554,094
39151.2.96.0/20151.2.96.1 to 151.2.111.254151.2.111.2554,094
40151.2.112.0/20151.2.112.1 to 151.2.127.254151.2.127.2554,094
41151.2.128.0/20151.2.128.1 to 151.2.143.254151.2.143.2554,094
42151.2.144.0/20151.2.144.1 to 151.2.159.254151.2.159.2554,094
43151.2.160.0/20151.2.160.1 to 151.2.175.254151.2.175.2554,094
44151.2.176.0/20151.2.176.1 to 151.2.191.254151.2.191.2554,094
45151.2.192.0/20151.2.192.1 to 151.2.207.254151.2.207.2554,094
46151.2.208.0/20151.2.208.1 to 151.2.223.254151.2.223.2554,094
47151.2.224.0/20151.2.224.1 to 151.2.239.254151.2.239.2554,094
48151.2.240.0/20151.2.240.1 to 151.2.255.254151.2.255.2554,094
49151.3.0.0/20151.3.0.1 to 151.3.15.254151.3.15.2554,094
50151.3.16.0/20151.3.16.1 to 151.3.31.254151.3.31.2554,094
51151.3.32.0/20151.3.32.1 to 151.3.47.254151.3.47.2554,094
52151.3.48.0/20151.3.48.1 to 151.3.63.254151.3.63.2554,094
53151.3.64.0/20151.3.64.1 to 151.3.79.254151.3.79.2554,094
54151.3.80.0/20151.3.80.1 to 151.3.95.254151.3.95.2554,094
55151.3.96.0/20151.3.96.1 to 151.3.111.254151.3.111.2554,094
56151.3.112.0/20151.3.112.1 to 151.3.127.254151.3.127.2554,094
57151.3.128.0/20151.3.128.1 to 151.3.143.254151.3.143.2554,094
58151.3.144.0/20151.3.144.1 to 151.3.159.254151.3.159.2554,094
59151.3.160.0/20151.3.160.1 to 151.3.175.254151.3.175.2554,094
60151.3.176.0/20151.3.176.1 to 151.3.191.254151.3.191.2554,094
61151.3.192.0/20151.3.192.1 to 151.3.207.254151.3.207.2554,094
62151.3.208.0/20151.3.208.1 to 151.3.223.254151.3.223.2554,094
63151.3.224.0/20151.3.224.1 to 151.3.239.254151.3.239.2554,094
64151.3.240.0/20151.3.240.1 to 151.3.255.254151.3.255.2554,094
65151.4.0.0/20151.4.0.1 to 151.4.15.254151.4.15.2554,094
66151.4.16.0/20151.4.16.1 to 151.4.31.254151.4.31.2554,094
67151.4.32.0/20151.4.32.1 to 151.4.47.254151.4.47.2554,094
68151.4.48.0/20151.4.48.1 to 151.4.63.254151.4.63.2554,094
69151.4.64.0/20151.4.64.1 to 151.4.79.254151.4.79.2554,094
70151.4.80.0/20151.4.80.1 to 151.4.95.254151.4.95.2554,094
71151.4.96.0/20151.4.96.1 to 151.4.111.254151.4.111.2554,094
72151.4.112.0/20151.4.112.1 to 151.4.127.254151.4.127.2554,094
73151.4.128.0/20151.4.128.1 to 151.4.143.254151.4.143.2554,094
74151.4.144.0/20151.4.144.1 to 151.4.159.254151.4.159.2554,094
75151.4.160.0/20151.4.160.1 to 151.4.175.254151.4.175.2554,094
76151.4.176.0/20151.4.176.1 to 151.4.191.254151.4.191.2554,094
77151.4.192.0/20151.4.192.1 to 151.4.207.254151.4.207.2554,094
78151.4.208.0/20151.4.208.1 to 151.4.223.254151.4.223.2554,094
79151.4.224.0/20151.4.224.1 to 151.4.239.254151.4.239.2554,094
80151.4.240.0/20151.4.240.1 to 151.4.255.254151.4.255.2554,094
81151.5.0.0/20151.5.0.1 to 151.5.15.254151.5.15.2554,094
82151.5.16.0/20151.5.16.1 to 151.5.31.254151.5.31.2554,094
83151.5.32.0/20151.5.32.1 to 151.5.47.254151.5.47.2554,094
84151.5.48.0/20151.5.48.1 to 151.5.63.254151.5.63.2554,094
85151.5.64.0/20151.5.64.1 to 151.5.79.254151.5.79.2554,094
86151.5.80.0/20151.5.80.1 to 151.5.95.254151.5.95.2554,094
87151.5.96.0/20151.5.96.1 to 151.5.111.254151.5.111.2554,094
88151.5.112.0/20151.5.112.1 to 151.5.127.254151.5.127.2554,094
89151.5.128.0/20151.5.128.1 to 151.5.143.254151.5.143.2554,094
90151.5.144.0/20151.5.144.1 to 151.5.159.254151.5.159.2554,094
91151.5.160.0/20151.5.160.1 to 151.5.175.254151.5.175.2554,094
92151.5.176.0/20151.5.176.1 to 151.5.191.254151.5.191.2554,094
93151.5.192.0/20151.5.192.1 to 151.5.207.254151.5.207.2554,094
94151.5.208.0/20151.5.208.1 to 151.5.223.254151.5.223.2554,094
95151.5.224.0/20151.5.224.1 to 151.5.239.254151.5.239.2554,094
96151.5.240.0/20151.5.240.1 to 151.5.255.254151.5.255.2554,094
97151.6.0.0/20151.6.0.1 to 151.6.15.254151.6.15.2554,094
98151.6.16.0/20151.6.16.1 to 151.6.31.254151.6.31.2554,094
99151.6.32.0/20151.6.32.1 to 151.6.47.254151.6.47.2554,094
100151.6.48.0/20151.6.48.1 to 151.6.63.254151.6.63.2554,094
101151.6.64.0/20151.6.64.1 to 151.6.79.254151.6.79.2554,094
102151.6.80.0/20151.6.80.1 to 151.6.95.254151.6.95.2554,094
103151.6.96.0/20151.6.96.1 to 151.6.111.254151.6.111.2554,094
104151.6.112.0/20151.6.112.1 to 151.6.127.254151.6.127.2554,094
105151.6.128.0/20151.6.128.1 to 151.6.143.254151.6.143.2554,094
106151.6.144.0/20151.6.144.1 to 151.6.159.254151.6.159.2554,094
107151.6.160.0/20151.6.160.1 to 151.6.175.254151.6.175.2554,094
108151.6.176.0/20151.6.176.1 to 151.6.191.254151.6.191.2554,094
109151.6.192.0/20151.6.192.1 to 151.6.207.254151.6.207.2554,094
110151.6.208.0/20151.6.208.1 to 151.6.223.254151.6.223.2554,094
111151.6.224.0/20151.6.224.1 to 151.6.239.254151.6.239.2554,094
112151.6.240.0/20151.6.240.1 to 151.6.255.254151.6.255.2554,094
113151.7.0.0/20151.7.0.1 to 151.7.15.254151.7.15.2554,094
114151.7.16.0/20151.7.16.1 to 151.7.31.254151.7.31.2554,094
115151.7.32.0/20151.7.32.1 to 151.7.47.254151.7.47.2554,094
116151.7.48.0/20151.7.48.1 to 151.7.63.254151.7.63.2554,094
117151.7.64.0/20151.7.64.1 to 151.7.79.254151.7.79.2554,094
118151.7.80.0/20151.7.80.1 to 151.7.95.254151.7.95.2554,094
119151.7.96.0/20151.7.96.1 to 151.7.111.254151.7.111.2554,094
120151.7.112.0/20151.7.112.1 to 151.7.127.254151.7.127.2554,094
121151.7.128.0/20151.7.128.1 to 151.7.143.254151.7.143.2554,094
122151.7.144.0/20151.7.144.1 to 151.7.159.254151.7.159.2554,094
123151.7.160.0/20151.7.160.1 to 151.7.175.254151.7.175.2554,094
124151.7.176.0/20151.7.176.1 to 151.7.191.254151.7.191.2554,094
125151.7.192.0/20151.7.192.1 to 151.7.207.254151.7.207.2554,094
126151.7.208.0/20151.7.208.1 to 151.7.223.254151.7.223.2554,094
127151.7.224.0/20151.7.224.1 to 151.7.239.254151.7.239.2554,094
128151.7.240.0/20151.7.240.1 to 151.7.255.254151.7.255.2554,094
129151.8.0.0/20151.8.0.1 to 151.8.15.254151.8.15.2554,094
130151.8.16.0/20151.8.16.1 to 151.8.31.254151.8.31.2554,094
131151.8.32.0/20151.8.32.1 to 151.8.47.254151.8.47.2554,094
132151.8.48.0/20151.8.48.1 to 151.8.63.254151.8.63.2554,094
133151.8.64.0/20151.8.64.1 to 151.8.79.254151.8.79.2554,094
134151.8.80.0/20151.8.80.1 to 151.8.95.254151.8.95.2554,094
135151.8.96.0/20151.8.96.1 to 151.8.111.254151.8.111.2554,094
136151.8.112.0/20151.8.112.1 to 151.8.127.254151.8.127.2554,094
137151.8.128.0/20151.8.128.1 to 151.8.143.254151.8.143.2554,094
138151.8.144.0/20151.8.144.1 to 151.8.159.254151.8.159.2554,094
139151.8.160.0/20151.8.160.1 to 151.8.175.254151.8.175.2554,094
140151.8.176.0/20151.8.176.1 to 151.8.191.254151.8.191.2554,094
141151.8.192.0/20151.8.192.1 to 151.8.207.254151.8.207.2554,094
142151.8.208.0/20151.8.208.1 to 151.8.223.254151.8.223.2554,094
143151.8.224.0/20151.8.224.1 to 151.8.239.254151.8.239.2554,094
144151.8.240.0/20151.8.240.1 to 151.8.255.254151.8.255.2554,094
145151.9.0.0/20151.9.0.1 to 151.9.15.254151.9.15.2554,094
146151.9.16.0/20151.9.16.1 to 151.9.31.254151.9.31.2554,094
147151.9.32.0/20151.9.32.1 to 151.9.47.254151.9.47.2554,094
148151.9.48.0/20151.9.48.1 to 151.9.63.254151.9.63.2554,094
149151.9.64.0/20151.9.64.1 to 151.9.79.254151.9.79.2554,094
150151.9.80.0/20151.9.80.1 to 151.9.95.254151.9.95.2554,094
151151.9.96.0/20151.9.96.1 to 151.9.111.254151.9.111.2554,094
152151.9.112.0/20151.9.112.1 to 151.9.127.254151.9.127.2554,094
153151.9.128.0/20151.9.128.1 to 151.9.143.254151.9.143.2554,094
154151.9.144.0/20151.9.144.1 to 151.9.159.254151.9.159.2554,094
155151.9.160.0/20151.9.160.1 to 151.9.175.254151.9.175.2554,094
156151.9.176.0/20151.9.176.1 to 151.9.191.254151.9.191.2554,094
157151.9.192.0/20151.9.192.1 to 151.9.207.254151.9.207.2554,094
158151.9.208.0/20151.9.208.1 to 151.9.223.254151.9.223.2554,094
159151.9.224.0/20151.9.224.1 to 151.9.239.254151.9.239.2554,094
160151.9.240.0/20151.9.240.1 to 151.9.255.254151.9.255.2554,094
161151.10.0.0/20151.10.0.1 to 151.10.15.254151.10.15.2554,094
162151.10.16.0/20151.10.16.1 to 151.10.31.254151.10.31.2554,094
163151.10.32.0/20151.10.32.1 to 151.10.47.254151.10.47.2554,094
164151.10.48.0/20151.10.48.1 to 151.10.63.254151.10.63.2554,094
165151.10.64.0/20151.10.64.1 to 151.10.79.254151.10.79.2554,094
166151.10.80.0/20151.10.80.1 to 151.10.95.254151.10.95.2554,094
167151.10.96.0/20151.10.96.1 to 151.10.111.254151.10.111.2554,094
168151.10.112.0/20151.10.112.1 to 151.10.127.254151.10.127.2554,094
169151.10.128.0/20151.10.128.1 to 151.10.143.254151.10.143.2554,094
170151.10.144.0/20151.10.144.1 to 151.10.159.254151.10.159.2554,094
171151.10.160.0/20151.10.160.1 to 151.10.175.254151.10.175.2554,094
172151.10.176.0/20151.10.176.1 to 151.10.191.254151.10.191.2554,094
173151.10.192.0/20151.10.192.1 to 151.10.207.254151.10.207.2554,094
174151.10.208.0/20151.10.208.1 to 151.10.223.254151.10.223.2554,094
175151.10.224.0/20151.10.224.1 to 151.10.239.254151.10.239.2554,094
176151.10.240.0/20151.10.240.1 to 151.10.255.254151.10.255.2554,094
177151.11.0.0/20151.11.0.1 to 151.11.15.254151.11.15.2554,094
178151.11.16.0/20151.11.16.1 to 151.11.31.254151.11.31.2554,094
179151.11.32.0/20151.11.32.1 to 151.11.47.254151.11.47.2554,094
180151.11.48.0/20151.11.48.1 to 151.11.63.254151.11.63.2554,094
181151.11.64.0/20151.11.64.1 to 151.11.79.254151.11.79.2554,094
182151.11.80.0/20151.11.80.1 to 151.11.95.254151.11.95.2554,094
183151.11.96.0/20151.11.96.1 to 151.11.111.254151.11.111.2554,094
184151.11.112.0/20151.11.112.1 to 151.11.127.254151.11.127.2554,094
185151.11.128.0/20151.11.128.1 to 151.11.143.254151.11.143.2554,094
186151.11.144.0/20151.11.144.1 to 151.11.159.254151.11.159.2554,094
187151.11.160.0/20151.11.160.1 to 151.11.175.254151.11.175.2554,094
188151.11.176.0/20151.11.176.1 to 151.11.191.254151.11.191.2554,094
189151.11.192.0/20151.11.192.1 to 151.11.207.254151.11.207.2554,094
190151.11.208.0/20151.11.208.1 to 151.11.223.254151.11.223.2554,094
191151.11.224.0/20151.11.224.1 to 151.11.239.254151.11.239.2554,094
192151.11.240.0/20151.11.240.1 to 151.11.255.254151.11.255.2554,094
193151.12.0.0/20151.12.0.1 to 151.12.15.254151.12.15.2554,094
194151.12.16.0/20151.12.16.1 to 151.12.31.254151.12.31.2554,094
195151.12.32.0/20151.12.32.1 to 151.12.47.254151.12.47.2554,094
196151.12.48.0/20151.12.48.1 to 151.12.63.254151.12.63.2554,094
197151.12.64.0/20151.12.64.1 to 151.12.79.254151.12.79.2554,094
198151.12.80.0/20151.12.80.1 to 151.12.95.254151.12.95.2554,094
199151.12.96.0/20151.12.96.1 to 151.12.111.254151.12.111.2554,094
200151.12.112.0/20151.12.112.1 to 151.12.127.254151.12.127.2554,094
201151.12.128.0/20151.12.128.1 to 151.12.143.254151.12.143.2554,094
202151.12.144.0/20151.12.144.1 to 151.12.159.254151.12.159.2554,094
203151.12.160.0/20151.12.160.1 to 151.12.175.254151.12.175.2554,094
204151.12.176.0/20151.12.176.1 to 151.12.191.254151.12.191.2554,094
205151.12.192.0/20151.12.192.1 to 151.12.207.254151.12.207.2554,094
206151.12.208.0/20151.12.208.1 to 151.12.223.254151.12.223.2554,094
207151.12.224.0/20151.12.224.1 to 151.12.239.254151.12.239.2554,094
208151.12.240.0/20151.12.240.1 to 151.12.255.254151.12.255.2554,094
209151.13.0.0/20151.13.0.1 to 151.13.15.254151.13.15.2554,094
210151.13.16.0/20151.13.16.1 to 151.13.31.254151.13.31.2554,094
211151.13.32.0/20151.13.32.1 to 151.13.47.254151.13.47.2554,094
212151.13.48.0/20151.13.48.1 to 151.13.63.254151.13.63.2554,094
213151.13.64.0/20151.13.64.1 to 151.13.79.254151.13.79.2554,094
214151.13.80.0/20151.13.80.1 to 151.13.95.254151.13.95.2554,094
215151.13.96.0/20151.13.96.1 to 151.13.111.254151.13.111.2554,094
216151.13.112.0/20151.13.112.1 to 151.13.127.254151.13.127.2554,094
217151.13.128.0/20151.13.128.1 to 151.13.143.254151.13.143.2554,094
218151.13.144.0/20151.13.144.1 to 151.13.159.254151.13.159.2554,094
219151.13.160.0/20151.13.160.1 to 151.13.175.254151.13.175.2554,094
220151.13.176.0/20151.13.176.1 to 151.13.191.254151.13.191.2554,094
221151.13.192.0/20151.13.192.1 to 151.13.207.254151.13.207.2554,094
222151.13.208.0/20151.13.208.1 to 151.13.223.254151.13.223.2554,094
223151.13.224.0/20151.13.224.1 to 151.13.239.254151.13.239.2554,094
224151.13.240.0/20151.13.240.1 to 151.13.255.254151.13.255.2554,094
225151.14.0.0/20151.14.0.1 to 151.14.15.254151.14.15.2554,094
226151.14.16.0/20151.14.16.1 to 151.14.31.254151.14.31.2554,094
227151.14.32.0/20151.14.32.1 to 151.14.47.254151.14.47.2554,094
228151.14.48.0/20151.14.48.1 to 151.14.63.254151.14.63.2554,094
229151.14.64.0/20151.14.64.1 to 151.14.79.254151.14.79.2554,094
230151.14.80.0/20151.14.80.1 to 151.14.95.254151.14.95.2554,094
231151.14.96.0/20151.14.96.1 to 151.14.111.254151.14.111.2554,094
232151.14.112.0/20151.14.112.1 to 151.14.127.254151.14.127.2554,094
233151.14.128.0/20151.14.128.1 to 151.14.143.254151.14.143.2554,094
234151.14.144.0/20151.14.144.1 to 151.14.159.254151.14.159.2554,094
235151.14.160.0/20151.14.160.1 to 151.14.175.254151.14.175.2554,094
236151.14.176.0/20151.14.176.1 to 151.14.191.254151.14.191.2554,094
237151.14.192.0/20151.14.192.1 to 151.14.207.254151.14.207.2554,094
238151.14.208.0/20151.14.208.1 to 151.14.223.254151.14.223.2554,094
239151.14.224.0/20151.14.224.1 to 151.14.239.254151.14.239.2554,094
240151.14.240.0/20151.14.240.1 to 151.14.255.254151.14.255.2554,094
241151.15.0.0/20151.15.0.1 to 151.15.15.254151.15.15.2554,094
242151.15.16.0/20151.15.16.1 to 151.15.31.254151.15.31.2554,094
243151.15.32.0/20151.15.32.1 to 151.15.47.254151.15.47.2554,094
244151.15.48.0/20151.15.48.1 to 151.15.63.254151.15.63.2554,094
245151.15.64.0/20151.15.64.1 to 151.15.79.254151.15.79.2554,094
246151.15.80.0/20151.15.80.1 to 151.15.95.254151.15.95.2554,094
247151.15.96.0/20151.15.96.1 to 151.15.111.254151.15.111.2554,094
248151.15.112.0/20151.15.112.1 to 151.15.127.254151.15.127.2554,094
249151.15.128.0/20151.15.128.1 to 151.15.143.254151.15.143.2554,094
250151.15.144.0/20151.15.144.1 to 151.15.159.254151.15.159.2554,094
251151.15.160.0/20151.15.160.1 to 151.15.175.254151.15.175.2554,094
252151.15.176.0/20151.15.176.1 to 151.15.191.254151.15.191.2554,094
253151.15.192.0/20151.15.192.1 to 151.15.207.254151.15.207.2554,094
254151.15.208.0/20151.15.208.1 to 151.15.223.254151.15.223.2554,094
255151.15.224.0/20151.15.224.1 to 151.15.239.254151.15.239.2554,094
256151.15.240.0/20151.15.240.1 to 151.15.255.254151.15.255.2554,094

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.