The principles are exactly the same for class A subnetting as they are for classes B and C.  We just have more host bits available.  We are going to keep this section fairly short since by now you have everything you need to answer any subnetting question.

Class A subnets:

Bits	Subnet Mask	CIDR	Subnets	Hosts
0	255.0.0.0	/8	1	16777216
1	255.128.0.0	/9	2	8388606
2	255.192.0.0	/10	4	4194302
3	255.224.0.0	/11	8	2097150
4	255.240.0.0	/12	16	1048574
5	255.248.0.0	/13	302	524286
6	255.252.0.0	/14	64	262142
7	255.254.0.0	/15	128	131070
8	255.255.0.0	/16	256	65534
9	255.255.128.0	/17	512	32766
10	255.255.192.0	/18	1024	16382
11	255.255.224.0	/19	2048	8190
12	255.255.240.0	/20	4096	4094
13	255.255.248.0	/21	8192	2046
14	255.255.252.0	/22	16384	1022
15	255.255.254.0	/23	32768	510
16	255.255.255.0	/24	65536	254
17	255.255.255.128	/25	131072	126
18	255.255.255.192	/26	262144	62
19	255.255.255.224	/27	524288	30
20	255.255.255.240	/28	1048576	14
21	255.255.255.248	/29	2097152	6
22	255.255.255.252	/30	4194304	2