CIDR Reference Table

CIDR 	Netmask			Reverse Netmask		IPs		Class Cs	Class Bs	Class As
/32	255.255.255.255		0.0.0.0			1		
/31	255.255.255.254		0.0.0.1			2
/30	255.255.255.252		0.0.0.3			4
/29	255.255.255.248		0.0.0.7			8
/28	255.255.255.240		0.0.0.15		16
/27	255.255.255.224		0.0.0.31		32
/26	255.255.255.192		0.0.0.63		64
/25	255.255.255.128		0.0.0.127		128
					
CIDR 	Netmask			Reverse Netmask		IPs
/24	255.255.255.0		0.0.0.255		256		1
/23	255.255.254.0		0.0.1.255		512		2
/22	255.255.252.0		0.0.3.255		1024		4
/21	255.255.248.0		0.0.7.255		2,048		8
/20	255.255.240.0		0.0.15.255		4,096		16
/19	255.255.224.0		0.0.31.255		8,192		32
/18	255.255.192.0		0.0.63.255		16,384		64
/17	255.255.128.0		0.0.127.255		32,768		128
	
CIDR 	Netmask			Reverse Netmask		IPs
/16	255.255.0.0		0.0.255.255		65,536		256		1
/15	255.254.0.0		0.1.255.255		131,072		512		2
/14	255.252.0.0		0.3.255.255		262,144		1,024		4
/13	255.248.0.0		0.7.255.255		524,288		2,048		8
/12	255.240.0.0		0.15.255.255		1,048,576	4,096		16
/11	255.224.0.0		0.31.255.255		2,097,152	8,192		32
/10	255.192.0.0		0.63.255.255		4,194,304	16,384		64
/9	255.128.0.0		0.127.255.255		8,388,608	32,768		128
	
CIDR 	Netmask			Reverse Netmask		IPs
/8	255.0.0.0		0.255.255.255		16,777,216	65,536		256		1
/7	254.0.0.0		1.255.255.255		33,554,432	131,072		512		2
/6	252.0.0.0		3.255.255.255		67,108,864	262,144		1,024		4
/5	248.0.0.0		7.255.255.255		134,217,728	524,288		2,048		8
/4	240.0.0.0		15.255.255.255		268,435,456	1,048,576	4,096		16
/3	224.0.0.0		31.255.255.255		536,870,912	2,097,152	8,192		32
/2	192.0.0.0		63.255.255.255		1,073,741,824	4,194,304	16,384		64
/1	128.0.0.0		127.255.255.255		2,147,483,648	8,388,608	32,768		128

CIDR 	Netmask			Reverse Netmask		IPs
/0	0.0.0.0			255.255.255.255		4,294,967,296	16,777,216	65,536		256