CIDR	  Netmask		Bit		Hosts		u.Hosts

/28  255.255.255.240		28		16		14
/27  255.255.255.224		27		32		30
/26  255.255.255.192		26 		64		62
/25  255.255.255.128		25 		128		126
/24  255.255.255.0		24		256 		254
/23  255.255.254.0		23		512 		510
/22  255.255.252.0		22		1,024		1,022
/21  255.255.248.0		21		2,048		2,046
/20  255.255.240.0		20		4,096		4,094
/19  255.255.224.0		19		8,192		8,190
/18  255.255.192.0		18		16,384 		16,382
/17  255.255.128.0		17		32,768 		32,766
/16  255.255.0.0 		16		65,536 		65,534
/15  255.254.0.0 		15		131,072 	131,070
/14  255.252.0.0  		14		262,144 	262,142
/13  255.248.0.0 		13		524,288 	524,286