Mask

Hosts

Usable

Netmask

Hex

Mask

/30

4

2

255.255.255.252

fffffffc

this is 1/64 of a Class C net

/29

8

6

255.255.255.248

fffffff8

this is 1/32 of a Class C net

/28

16

14

255.255.255.240

fffffff0

this is 1/16 of a Class C net

/27

32

30

255.255.255.224

ffffffe0

this is 1/8 of a Class C net

/26

64

62

255.255.255.192

ffffffc0

this is 1/4 of a Class C net

/24

256

254

255.255.255.0

ffffff00

this is a Class C net

/23

512

510

255.255.254.0

fffffe00

these are 2 Class C net

/22

1024

1022

255.255.252.0

fffffc00

these are 4 Class C net

/21

2048

2046

255.255.248.0

fffff800

these are 8 Class C net

/20

4096

4094

255.255.240.0

fffff000

these are 16 Class C net

/19

8192

8190

255.255.224.0

ffffe000

these are 32 Class C net

/18

16384

16382

255.255.192.0

ffffc000

these are 64 Class C net

/17

32768

32766

255.255.128.0

ffff8000

these are 128 Class C net

/16

65536

65534

255.255.0.0

ffff0000

these are 256 Class C net = Class B net