IPv4 CIDR Chart

VLSM/CIDR Reference Table (IPv4 Subnetting Chart)

Class	Prefix	Subnet Mask	Subnets	Hosts / Usable IPs	Bits used
C	/31	255.255.255.254	128	2 (ppp only)	7 / 1
	/30	255.255.255.252	64	4 (2)	6 / 2
	/29	255.255.255.248	32	8 (6)	5 / 3
	/28	255.255.255.240	16	16 (14)	4 / 4
	/27	255.255.255.224	8	32 (30)	3 / 5
	/26	255.255.255.192	4	64 (62)	2 / 6
	/25	255.255.255.128	2	128 (126)	1 / 7
	/24	255.255.255.0	0	256 (254)	0 / 8
B	/23	255.255.254.0	128	512 (510)	7 / 9
	/22	255.255.252.0	64	1024 (1022)	6 / 10
	/21	255.255.248.0	32	2048 (2046)	5 / 11
	/20	255.255.240.0	16	4096 (4094)	4 / 12
	/19	255.255.224.0	8	8292 (8290)	3 / 13
	/18	255.255.192.0	4	16384 (16382)	2 / 14
	/17	255.255.128.0	2	32768 (32766)	1 / 15
	/16	255.255.0.0	0	65536 (65534)	0 / 16
A	/15	255.254.0.0	128	131072 (- 2)	7 / 17
	/14	255.252.0.0	64	262144 (- 2)	6 / 18
	/13	255.248.0.0	32	524288 (- 2)	5 / 19
	/12	255.240.0.0	16	1048576 (- 2)	4 / 20
	/11	255.224.0.0	8	2097152 (- 2)	3 / 21
	/10	255.192.0.0	4	4194304 (- 2)	2 / 22
	/9	255.128.0.0	2	8388608 (- 2)	1 / 23
	/8	255.0.0.0	0	16777216 (- 2)	0 / 24