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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.

Network133.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
133.0.0.0
Broadcast address
133.255.255.255
First usable
133.0.0.1
Last usable
133.255.255.254
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 85000000 · Integer 2231369728 to 2248146943
Reverse DNS zone
133.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000101..00000000.00000000.00000000133.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10000101..00000000.00000000.00000000133.0.0.0
Broadcast10000101..11111111.11111111.11111111133.255.255.255
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)

133.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1133.0.0.0/20133.0.0.1 to 133.0.15.254133.0.15.2554,094
2133.0.16.0/20133.0.16.1 to 133.0.31.254133.0.31.2554,094
3133.0.32.0/20133.0.32.1 to 133.0.47.254133.0.47.2554,094
4133.0.48.0/20133.0.48.1 to 133.0.63.254133.0.63.2554,094
5133.0.64.0/20133.0.64.1 to 133.0.79.254133.0.79.2554,094
6133.0.80.0/20133.0.80.1 to 133.0.95.254133.0.95.2554,094
7133.0.96.0/20133.0.96.1 to 133.0.111.254133.0.111.2554,094
8133.0.112.0/20133.0.112.1 to 133.0.127.254133.0.127.2554,094
9133.0.128.0/20133.0.128.1 to 133.0.143.254133.0.143.2554,094
10133.0.144.0/20133.0.144.1 to 133.0.159.254133.0.159.2554,094
11133.0.160.0/20133.0.160.1 to 133.0.175.254133.0.175.2554,094
12133.0.176.0/20133.0.176.1 to 133.0.191.254133.0.191.2554,094
13133.0.192.0/20133.0.192.1 to 133.0.207.254133.0.207.2554,094
14133.0.208.0/20133.0.208.1 to 133.0.223.254133.0.223.2554,094
15133.0.224.0/20133.0.224.1 to 133.0.239.254133.0.239.2554,094
16133.0.240.0/20133.0.240.1 to 133.0.255.254133.0.255.2554,094
17133.1.0.0/20133.1.0.1 to 133.1.15.254133.1.15.2554,094
18133.1.16.0/20133.1.16.1 to 133.1.31.254133.1.31.2554,094
19133.1.32.0/20133.1.32.1 to 133.1.47.254133.1.47.2554,094
20133.1.48.0/20133.1.48.1 to 133.1.63.254133.1.63.2554,094
21133.1.64.0/20133.1.64.1 to 133.1.79.254133.1.79.2554,094
22133.1.80.0/20133.1.80.1 to 133.1.95.254133.1.95.2554,094
23133.1.96.0/20133.1.96.1 to 133.1.111.254133.1.111.2554,094
24133.1.112.0/20133.1.112.1 to 133.1.127.254133.1.127.2554,094
25133.1.128.0/20133.1.128.1 to 133.1.143.254133.1.143.2554,094
26133.1.144.0/20133.1.144.1 to 133.1.159.254133.1.159.2554,094
27133.1.160.0/20133.1.160.1 to 133.1.175.254133.1.175.2554,094
28133.1.176.0/20133.1.176.1 to 133.1.191.254133.1.191.2554,094
29133.1.192.0/20133.1.192.1 to 133.1.207.254133.1.207.2554,094
30133.1.208.0/20133.1.208.1 to 133.1.223.254133.1.223.2554,094
31133.1.224.0/20133.1.224.1 to 133.1.239.254133.1.239.2554,094
32133.1.240.0/20133.1.240.1 to 133.1.255.254133.1.255.2554,094
33133.2.0.0/20133.2.0.1 to 133.2.15.254133.2.15.2554,094
34133.2.16.0/20133.2.16.1 to 133.2.31.254133.2.31.2554,094
35133.2.32.0/20133.2.32.1 to 133.2.47.254133.2.47.2554,094
36133.2.48.0/20133.2.48.1 to 133.2.63.254133.2.63.2554,094
37133.2.64.0/20133.2.64.1 to 133.2.79.254133.2.79.2554,094
38133.2.80.0/20133.2.80.1 to 133.2.95.254133.2.95.2554,094
39133.2.96.0/20133.2.96.1 to 133.2.111.254133.2.111.2554,094
40133.2.112.0/20133.2.112.1 to 133.2.127.254133.2.127.2554,094
41133.2.128.0/20133.2.128.1 to 133.2.143.254133.2.143.2554,094
42133.2.144.0/20133.2.144.1 to 133.2.159.254133.2.159.2554,094
43133.2.160.0/20133.2.160.1 to 133.2.175.254133.2.175.2554,094
44133.2.176.0/20133.2.176.1 to 133.2.191.254133.2.191.2554,094
45133.2.192.0/20133.2.192.1 to 133.2.207.254133.2.207.2554,094
46133.2.208.0/20133.2.208.1 to 133.2.223.254133.2.223.2554,094
47133.2.224.0/20133.2.224.1 to 133.2.239.254133.2.239.2554,094
48133.2.240.0/20133.2.240.1 to 133.2.255.254133.2.255.2554,094
49133.3.0.0/20133.3.0.1 to 133.3.15.254133.3.15.2554,094
50133.3.16.0/20133.3.16.1 to 133.3.31.254133.3.31.2554,094
51133.3.32.0/20133.3.32.1 to 133.3.47.254133.3.47.2554,094
52133.3.48.0/20133.3.48.1 to 133.3.63.254133.3.63.2554,094
53133.3.64.0/20133.3.64.1 to 133.3.79.254133.3.79.2554,094
54133.3.80.0/20133.3.80.1 to 133.3.95.254133.3.95.2554,094
55133.3.96.0/20133.3.96.1 to 133.3.111.254133.3.111.2554,094
56133.3.112.0/20133.3.112.1 to 133.3.127.254133.3.127.2554,094
57133.3.128.0/20133.3.128.1 to 133.3.143.254133.3.143.2554,094
58133.3.144.0/20133.3.144.1 to 133.3.159.254133.3.159.2554,094
59133.3.160.0/20133.3.160.1 to 133.3.175.254133.3.175.2554,094
60133.3.176.0/20133.3.176.1 to 133.3.191.254133.3.191.2554,094
61133.3.192.0/20133.3.192.1 to 133.3.207.254133.3.207.2554,094
62133.3.208.0/20133.3.208.1 to 133.3.223.254133.3.223.2554,094
63133.3.224.0/20133.3.224.1 to 133.3.239.254133.3.239.2554,094
64133.3.240.0/20133.3.240.1 to 133.3.255.254133.3.255.2554,094
65133.4.0.0/20133.4.0.1 to 133.4.15.254133.4.15.2554,094
66133.4.16.0/20133.4.16.1 to 133.4.31.254133.4.31.2554,094
67133.4.32.0/20133.4.32.1 to 133.4.47.254133.4.47.2554,094
68133.4.48.0/20133.4.48.1 to 133.4.63.254133.4.63.2554,094
69133.4.64.0/20133.4.64.1 to 133.4.79.254133.4.79.2554,094
70133.4.80.0/20133.4.80.1 to 133.4.95.254133.4.95.2554,094
71133.4.96.0/20133.4.96.1 to 133.4.111.254133.4.111.2554,094
72133.4.112.0/20133.4.112.1 to 133.4.127.254133.4.127.2554,094
73133.4.128.0/20133.4.128.1 to 133.4.143.254133.4.143.2554,094
74133.4.144.0/20133.4.144.1 to 133.4.159.254133.4.159.2554,094
75133.4.160.0/20133.4.160.1 to 133.4.175.254133.4.175.2554,094
76133.4.176.0/20133.4.176.1 to 133.4.191.254133.4.191.2554,094
77133.4.192.0/20133.4.192.1 to 133.4.207.254133.4.207.2554,094
78133.4.208.0/20133.4.208.1 to 133.4.223.254133.4.223.2554,094
79133.4.224.0/20133.4.224.1 to 133.4.239.254133.4.239.2554,094
80133.4.240.0/20133.4.240.1 to 133.4.255.254133.4.255.2554,094
81133.5.0.0/20133.5.0.1 to 133.5.15.254133.5.15.2554,094
82133.5.16.0/20133.5.16.1 to 133.5.31.254133.5.31.2554,094
83133.5.32.0/20133.5.32.1 to 133.5.47.254133.5.47.2554,094
84133.5.48.0/20133.5.48.1 to 133.5.63.254133.5.63.2554,094
85133.5.64.0/20133.5.64.1 to 133.5.79.254133.5.79.2554,094
86133.5.80.0/20133.5.80.1 to 133.5.95.254133.5.95.2554,094
87133.5.96.0/20133.5.96.1 to 133.5.111.254133.5.111.2554,094
88133.5.112.0/20133.5.112.1 to 133.5.127.254133.5.127.2554,094
89133.5.128.0/20133.5.128.1 to 133.5.143.254133.5.143.2554,094
90133.5.144.0/20133.5.144.1 to 133.5.159.254133.5.159.2554,094
91133.5.160.0/20133.5.160.1 to 133.5.175.254133.5.175.2554,094
92133.5.176.0/20133.5.176.1 to 133.5.191.254133.5.191.2554,094
93133.5.192.0/20133.5.192.1 to 133.5.207.254133.5.207.2554,094
94133.5.208.0/20133.5.208.1 to 133.5.223.254133.5.223.2554,094
95133.5.224.0/20133.5.224.1 to 133.5.239.254133.5.239.2554,094
96133.5.240.0/20133.5.240.1 to 133.5.255.254133.5.255.2554,094
97133.6.0.0/20133.6.0.1 to 133.6.15.254133.6.15.2554,094
98133.6.16.0/20133.6.16.1 to 133.6.31.254133.6.31.2554,094
99133.6.32.0/20133.6.32.1 to 133.6.47.254133.6.47.2554,094
100133.6.48.0/20133.6.48.1 to 133.6.63.254133.6.63.2554,094
101133.6.64.0/20133.6.64.1 to 133.6.79.254133.6.79.2554,094
102133.6.80.0/20133.6.80.1 to 133.6.95.254133.6.95.2554,094
103133.6.96.0/20133.6.96.1 to 133.6.111.254133.6.111.2554,094
104133.6.112.0/20133.6.112.1 to 133.6.127.254133.6.127.2554,094
105133.6.128.0/20133.6.128.1 to 133.6.143.254133.6.143.2554,094
106133.6.144.0/20133.6.144.1 to 133.6.159.254133.6.159.2554,094
107133.6.160.0/20133.6.160.1 to 133.6.175.254133.6.175.2554,094
108133.6.176.0/20133.6.176.1 to 133.6.191.254133.6.191.2554,094
109133.6.192.0/20133.6.192.1 to 133.6.207.254133.6.207.2554,094
110133.6.208.0/20133.6.208.1 to 133.6.223.254133.6.223.2554,094
111133.6.224.0/20133.6.224.1 to 133.6.239.254133.6.239.2554,094
112133.6.240.0/20133.6.240.1 to 133.6.255.254133.6.255.2554,094
113133.7.0.0/20133.7.0.1 to 133.7.15.254133.7.15.2554,094
114133.7.16.0/20133.7.16.1 to 133.7.31.254133.7.31.2554,094
115133.7.32.0/20133.7.32.1 to 133.7.47.254133.7.47.2554,094
116133.7.48.0/20133.7.48.1 to 133.7.63.254133.7.63.2554,094
117133.7.64.0/20133.7.64.1 to 133.7.79.254133.7.79.2554,094
118133.7.80.0/20133.7.80.1 to 133.7.95.254133.7.95.2554,094
119133.7.96.0/20133.7.96.1 to 133.7.111.254133.7.111.2554,094
120133.7.112.0/20133.7.112.1 to 133.7.127.254133.7.127.2554,094
121133.7.128.0/20133.7.128.1 to 133.7.143.254133.7.143.2554,094
122133.7.144.0/20133.7.144.1 to 133.7.159.254133.7.159.2554,094
123133.7.160.0/20133.7.160.1 to 133.7.175.254133.7.175.2554,094
124133.7.176.0/20133.7.176.1 to 133.7.191.254133.7.191.2554,094
125133.7.192.0/20133.7.192.1 to 133.7.207.254133.7.207.2554,094
126133.7.208.0/20133.7.208.1 to 133.7.223.254133.7.223.2554,094
127133.7.224.0/20133.7.224.1 to 133.7.239.254133.7.239.2554,094
128133.7.240.0/20133.7.240.1 to 133.7.255.254133.7.255.2554,094
129133.8.0.0/20133.8.0.1 to 133.8.15.254133.8.15.2554,094
130133.8.16.0/20133.8.16.1 to 133.8.31.254133.8.31.2554,094
131133.8.32.0/20133.8.32.1 to 133.8.47.254133.8.47.2554,094
132133.8.48.0/20133.8.48.1 to 133.8.63.254133.8.63.2554,094
133133.8.64.0/20133.8.64.1 to 133.8.79.254133.8.79.2554,094
134133.8.80.0/20133.8.80.1 to 133.8.95.254133.8.95.2554,094
135133.8.96.0/20133.8.96.1 to 133.8.111.254133.8.111.2554,094
136133.8.112.0/20133.8.112.1 to 133.8.127.254133.8.127.2554,094
137133.8.128.0/20133.8.128.1 to 133.8.143.254133.8.143.2554,094
138133.8.144.0/20133.8.144.1 to 133.8.159.254133.8.159.2554,094
139133.8.160.0/20133.8.160.1 to 133.8.175.254133.8.175.2554,094
140133.8.176.0/20133.8.176.1 to 133.8.191.254133.8.191.2554,094
141133.8.192.0/20133.8.192.1 to 133.8.207.254133.8.207.2554,094
142133.8.208.0/20133.8.208.1 to 133.8.223.254133.8.223.2554,094
143133.8.224.0/20133.8.224.1 to 133.8.239.254133.8.239.2554,094
144133.8.240.0/20133.8.240.1 to 133.8.255.254133.8.255.2554,094
145133.9.0.0/20133.9.0.1 to 133.9.15.254133.9.15.2554,094
146133.9.16.0/20133.9.16.1 to 133.9.31.254133.9.31.2554,094
147133.9.32.0/20133.9.32.1 to 133.9.47.254133.9.47.2554,094
148133.9.48.0/20133.9.48.1 to 133.9.63.254133.9.63.2554,094
149133.9.64.0/20133.9.64.1 to 133.9.79.254133.9.79.2554,094
150133.9.80.0/20133.9.80.1 to 133.9.95.254133.9.95.2554,094
151133.9.96.0/20133.9.96.1 to 133.9.111.254133.9.111.2554,094
152133.9.112.0/20133.9.112.1 to 133.9.127.254133.9.127.2554,094
153133.9.128.0/20133.9.128.1 to 133.9.143.254133.9.143.2554,094
154133.9.144.0/20133.9.144.1 to 133.9.159.254133.9.159.2554,094
155133.9.160.0/20133.9.160.1 to 133.9.175.254133.9.175.2554,094
156133.9.176.0/20133.9.176.1 to 133.9.191.254133.9.191.2554,094
157133.9.192.0/20133.9.192.1 to 133.9.207.254133.9.207.2554,094
158133.9.208.0/20133.9.208.1 to 133.9.223.254133.9.223.2554,094
159133.9.224.0/20133.9.224.1 to 133.9.239.254133.9.239.2554,094
160133.9.240.0/20133.9.240.1 to 133.9.255.254133.9.255.2554,094
161133.10.0.0/20133.10.0.1 to 133.10.15.254133.10.15.2554,094
162133.10.16.0/20133.10.16.1 to 133.10.31.254133.10.31.2554,094
163133.10.32.0/20133.10.32.1 to 133.10.47.254133.10.47.2554,094
164133.10.48.0/20133.10.48.1 to 133.10.63.254133.10.63.2554,094
165133.10.64.0/20133.10.64.1 to 133.10.79.254133.10.79.2554,094
166133.10.80.0/20133.10.80.1 to 133.10.95.254133.10.95.2554,094
167133.10.96.0/20133.10.96.1 to 133.10.111.254133.10.111.2554,094
168133.10.112.0/20133.10.112.1 to 133.10.127.254133.10.127.2554,094
169133.10.128.0/20133.10.128.1 to 133.10.143.254133.10.143.2554,094
170133.10.144.0/20133.10.144.1 to 133.10.159.254133.10.159.2554,094
171133.10.160.0/20133.10.160.1 to 133.10.175.254133.10.175.2554,094
172133.10.176.0/20133.10.176.1 to 133.10.191.254133.10.191.2554,094
173133.10.192.0/20133.10.192.1 to 133.10.207.254133.10.207.2554,094
174133.10.208.0/20133.10.208.1 to 133.10.223.254133.10.223.2554,094
175133.10.224.0/20133.10.224.1 to 133.10.239.254133.10.239.2554,094
176133.10.240.0/20133.10.240.1 to 133.10.255.254133.10.255.2554,094
177133.11.0.0/20133.11.0.1 to 133.11.15.254133.11.15.2554,094
178133.11.16.0/20133.11.16.1 to 133.11.31.254133.11.31.2554,094
179133.11.32.0/20133.11.32.1 to 133.11.47.254133.11.47.2554,094
180133.11.48.0/20133.11.48.1 to 133.11.63.254133.11.63.2554,094
181133.11.64.0/20133.11.64.1 to 133.11.79.254133.11.79.2554,094
182133.11.80.0/20133.11.80.1 to 133.11.95.254133.11.95.2554,094
183133.11.96.0/20133.11.96.1 to 133.11.111.254133.11.111.2554,094
184133.11.112.0/20133.11.112.1 to 133.11.127.254133.11.127.2554,094
185133.11.128.0/20133.11.128.1 to 133.11.143.254133.11.143.2554,094
186133.11.144.0/20133.11.144.1 to 133.11.159.254133.11.159.2554,094
187133.11.160.0/20133.11.160.1 to 133.11.175.254133.11.175.2554,094
188133.11.176.0/20133.11.176.1 to 133.11.191.254133.11.191.2554,094
189133.11.192.0/20133.11.192.1 to 133.11.207.254133.11.207.2554,094
190133.11.208.0/20133.11.208.1 to 133.11.223.254133.11.223.2554,094
191133.11.224.0/20133.11.224.1 to 133.11.239.254133.11.239.2554,094
192133.11.240.0/20133.11.240.1 to 133.11.255.254133.11.255.2554,094
193133.12.0.0/20133.12.0.1 to 133.12.15.254133.12.15.2554,094
194133.12.16.0/20133.12.16.1 to 133.12.31.254133.12.31.2554,094
195133.12.32.0/20133.12.32.1 to 133.12.47.254133.12.47.2554,094
196133.12.48.0/20133.12.48.1 to 133.12.63.254133.12.63.2554,094
197133.12.64.0/20133.12.64.1 to 133.12.79.254133.12.79.2554,094
198133.12.80.0/20133.12.80.1 to 133.12.95.254133.12.95.2554,094
199133.12.96.0/20133.12.96.1 to 133.12.111.254133.12.111.2554,094
200133.12.112.0/20133.12.112.1 to 133.12.127.254133.12.127.2554,094
201133.12.128.0/20133.12.128.1 to 133.12.143.254133.12.143.2554,094
202133.12.144.0/20133.12.144.1 to 133.12.159.254133.12.159.2554,094
203133.12.160.0/20133.12.160.1 to 133.12.175.254133.12.175.2554,094
204133.12.176.0/20133.12.176.1 to 133.12.191.254133.12.191.2554,094
205133.12.192.0/20133.12.192.1 to 133.12.207.254133.12.207.2554,094
206133.12.208.0/20133.12.208.1 to 133.12.223.254133.12.223.2554,094
207133.12.224.0/20133.12.224.1 to 133.12.239.254133.12.239.2554,094
208133.12.240.0/20133.12.240.1 to 133.12.255.254133.12.255.2554,094
209133.13.0.0/20133.13.0.1 to 133.13.15.254133.13.15.2554,094
210133.13.16.0/20133.13.16.1 to 133.13.31.254133.13.31.2554,094
211133.13.32.0/20133.13.32.1 to 133.13.47.254133.13.47.2554,094
212133.13.48.0/20133.13.48.1 to 133.13.63.254133.13.63.2554,094
213133.13.64.0/20133.13.64.1 to 133.13.79.254133.13.79.2554,094
214133.13.80.0/20133.13.80.1 to 133.13.95.254133.13.95.2554,094
215133.13.96.0/20133.13.96.1 to 133.13.111.254133.13.111.2554,094
216133.13.112.0/20133.13.112.1 to 133.13.127.254133.13.127.2554,094
217133.13.128.0/20133.13.128.1 to 133.13.143.254133.13.143.2554,094
218133.13.144.0/20133.13.144.1 to 133.13.159.254133.13.159.2554,094
219133.13.160.0/20133.13.160.1 to 133.13.175.254133.13.175.2554,094
220133.13.176.0/20133.13.176.1 to 133.13.191.254133.13.191.2554,094
221133.13.192.0/20133.13.192.1 to 133.13.207.254133.13.207.2554,094
222133.13.208.0/20133.13.208.1 to 133.13.223.254133.13.223.2554,094
223133.13.224.0/20133.13.224.1 to 133.13.239.254133.13.239.2554,094
224133.13.240.0/20133.13.240.1 to 133.13.255.254133.13.255.2554,094
225133.14.0.0/20133.14.0.1 to 133.14.15.254133.14.15.2554,094
226133.14.16.0/20133.14.16.1 to 133.14.31.254133.14.31.2554,094
227133.14.32.0/20133.14.32.1 to 133.14.47.254133.14.47.2554,094
228133.14.48.0/20133.14.48.1 to 133.14.63.254133.14.63.2554,094
229133.14.64.0/20133.14.64.1 to 133.14.79.254133.14.79.2554,094
230133.14.80.0/20133.14.80.1 to 133.14.95.254133.14.95.2554,094
231133.14.96.0/20133.14.96.1 to 133.14.111.254133.14.111.2554,094
232133.14.112.0/20133.14.112.1 to 133.14.127.254133.14.127.2554,094
233133.14.128.0/20133.14.128.1 to 133.14.143.254133.14.143.2554,094
234133.14.144.0/20133.14.144.1 to 133.14.159.254133.14.159.2554,094
235133.14.160.0/20133.14.160.1 to 133.14.175.254133.14.175.2554,094
236133.14.176.0/20133.14.176.1 to 133.14.191.254133.14.191.2554,094
237133.14.192.0/20133.14.192.1 to 133.14.207.254133.14.207.2554,094
238133.14.208.0/20133.14.208.1 to 133.14.223.254133.14.223.2554,094
239133.14.224.0/20133.14.224.1 to 133.14.239.254133.14.239.2554,094
240133.14.240.0/20133.14.240.1 to 133.14.255.254133.14.255.2554,094
241133.15.0.0/20133.15.0.1 to 133.15.15.254133.15.15.2554,094
242133.15.16.0/20133.15.16.1 to 133.15.31.254133.15.31.2554,094
243133.15.32.0/20133.15.32.1 to 133.15.47.254133.15.47.2554,094
244133.15.48.0/20133.15.48.1 to 133.15.63.254133.15.63.2554,094
245133.15.64.0/20133.15.64.1 to 133.15.79.254133.15.79.2554,094
246133.15.80.0/20133.15.80.1 to 133.15.95.254133.15.95.2554,094
247133.15.96.0/20133.15.96.1 to 133.15.111.254133.15.111.2554,094
248133.15.112.0/20133.15.112.1 to 133.15.127.254133.15.127.2554,094
249133.15.128.0/20133.15.128.1 to 133.15.143.254133.15.143.2554,094
250133.15.144.0/20133.15.144.1 to 133.15.159.254133.15.159.2554,094
251133.15.160.0/20133.15.160.1 to 133.15.175.254133.15.175.2554,094
252133.15.176.0/20133.15.176.1 to 133.15.191.254133.15.191.2554,094
253133.15.192.0/20133.15.192.1 to 133.15.207.254133.15.207.2554,094
254133.15.208.0/20133.15.208.1 to 133.15.223.254133.15.223.2554,094
255133.15.224.0/20133.15.224.1 to 133.15.239.254133.15.239.2554,094
256133.15.240.0/20133.15.240.1 to 133.15.255.254133.15.255.2554,094

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.