Subnet Mask Cheat Sheet

	Addresses	Host	Netmask	Amount of a Class C
/30	4	2	255.255.255.252	1/64
/38	8	6	255.255.255.248	1/32
/28	16	14	255.255.255.240	1/16
/27	32	30	255.255.255.224	1/8
/26	64	62	255.255.255.192	1/4
/25	128	126	255.255.255.128	1/2
/24	256	254	255.255.255.0	1
/23	512	510	255.255.254.0	2
/22	1024	1022	255.255.252.0	4
/21	2048	2046	255.255.248.0	8
/20	4096	4094	255.255.240.0	16
/19	8192	8190	255.255.224.0	32
/18	16384	16382	255.255.192.0	64
/18	32768	32766	255.255.128.0	128
/16	65536	65534	255.255.0.0	256

Guide to sub-class C blocks

Network #	IP Range	Broadcast
.0	.1 – .126	.127
.128	.129 – .254	.255

/25 — 2 Subnets — 126 Hosts/Subnet