CIDR Cheat Sheet: See How Many IP Addresses Are Usable

Catch yourself asking…

How many IP addresses are there in a /24? /27? /30?

Yeah, well, no more!

Use the following CIDR cheat sheet to see what the corresponding subnet masks, total IPs, and usable IPs are.

CIDRSubnet MaskTotal IPsUsable IPs
/00.0.0.04,294,967,2964,294,967,294
/1128.0.0.02,147,483,6482,147,483,646
/2192.0.0.01,073,741,8241,073,741,822
/3224.0.0.0536,870,912536,870,910
/4240.0.0.0268,435,456268,435,454
/5248.0.0.0134,217,728134,217,726
/6252.0.0.067,108,86467,108,862
/7254.0.0.033,554,43233,554,430
/8255.0.0.016,777,21616,777,214
/9255.128.0.08,388,6088,388,606
/10255.192.0.04,194,3044,194,302
/11255.224.0.02,097,1522,097,150
/12255.240.0.01,048,5761,048,574
/13255.248.0.0524,288524,286
/14255.252.0.0262,1442621,42
/15255.254.0.0131,072131,070
/16255.255.0.065,53665,534
/17255.255.128.032,76832,766
/18255.255.192.016,38416,382
/19255.255.224.08,1928,190
/20255.255.240.04,0964,094
/21255.255.248.02,0482,046
/22255.255.252.01,0241,022
/23255.255.254.0512510
/24255.255.255.0256254
/25255.255.255.128128126
/26255.255.255.1926462
/27255.255.255.2243230
/28255.255.255.2401614
/29255.255.255.24886
/30255.255.255.25242
/31255.255.255.25420
/32255.255.255.25511

Classful Ranges

 FromTo
A0.0.0.0127.255.255.255
B128.0.0.0191.255.255.255
C192.0.0.0223.255.255.255
D224.0.0.0239.255.255.255
E240.0.0.0255.255.255.255

Reserved Ranges

 FromTo
RFC 191810.0.0.010.255.255.255
Localhost127.0.0.0127.255.255.255
RFC 1918172.16.0.0172.31.255.255
RFC 1918192.168.0.0192.168.255.255

Decimal to Binary

Subnet MaskWildcard
00000000025511111111
1281000000012701111111
192110000006300111111
224111000003100011111
240111100001500001111
24811111000700000111
25211111100300000011
25411111110100000001
25511111111000000000
Dan Alder

Dan Alder

Dan is an avid gamer. He's logged far too many hours in CS 1.6. As an engineering major he's also very experienced in electronics.
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