CIDR-IP Range

See in comments

CIDR Prefix	Subnet Mask	Total IP's	Usable IP's	Relative size to other block sizes
a.b.c.d**/32**	255.255.255.255	1	1	1/256 C
a.b.c.d**/31**	255.255.255.254	2	0	1/128 C
a.b.c.d**/30**	255.255.255.252	4	2	1/64 C
a.b.c.d**/29**	255.255.255.248	8	6	1/32 C
a.b.c.d**/28**	255.255.255.240	16	14	1/16 C
a.b.c.d**/27**	255.255.255.224	32	30	1/8 C
a.b.c.d**/26**	255.255.255.192	64	62	¼ C
a.b.c.d**/25**	255.255.255.128	128	126	½ C
a.b.c.0**/24**	255.255.255.0	256	254	1 C
a.b.c.0**/23**	255.255.254.0	512	510	2 C
a.b.c.0**/22**	255.255.252.0	1024	1022	4 C
a.b.c.0**/21**	255.255.248.0	2048	2046	8 C
a.b.c.0**/20**	255.255.240.0	4096	4094	16 C
a.b.c.0**/19**	255.255.224.0	8192	8190	32 C
a.b.c.0**/18**	255.255.192.0	16,384	16,382	64 C
a.b.c.0**/17**	255.255.128.0	32,768	32,766	128 C
a.b.0.0**/16**	255.255.0.0	65,536	65,534	256 C = 1 B
a.b.0.0**/15**	255.254.0.0	131,072	131,070	2 B
a.b.0.0**/14**	255.252.0.0	262,144	262,142	4 B
a.b.0.0**/13**	255.248.0.0	524,288	524,286	8 B
a.b.0.0**/12**	255.240.0.0	1,048,576	1,048,574	16 B
a.b.0.0**/11**	255.224.0.0	2,097,152	2,097,150	32 B
a.b.0.0**/10**	255.192.0.0	4,194,304	4,194,302	64 B
a.b.0.0**/9**	255.128.0.0	8,388,608	8,388,606	128 B
a.0.0.0**/8**	255.0.0.0	16,777,216	16,777,214	256 B = 1 A
a.0.0.0**/7**	254.0.0.0	33,554,432	33,554,430	2 A
a.0.0.0**/6**	252.0.0.0	67,108,864	67,108,862	4 A
a.0.0.0**/5**	248.0.0.0	134,217,728	134,217,726	8 A
a.0.0.0**/4**	240.0.0.0	268,435,456	268,435,454	16 A
a.0.0.0**/3**	224.0.0.0	536,870,912	536,870,910	32 A
a.0.0.0**/2**	192.0.0.0	1,073,741,824	1,073,741,822	64 A
a.0.0.0**/1**	128.0.0.0	2,147,483,648	2,147,483,646	128 A
0.0.0.0**/0**	0.0.0.0	4,294,967,296	4,294,967,294	256 A

Reserved Network Numbers

Class	Start	End	# Hosts	Comment
A	10.0.0.0	10.255.255.255	16,777,216	a single Class A network number
B	172.16.0.0	172.31.255.255	1,048,544	16 contiguous Class B network numbers
C	192.168.0.0	192.168.255.255	65,534	256 contiguous Class C network numbers