# of Subnet ID Bit

# of Host ID Bits

# of Subnets Per Network

# of
Hosts Per Subnet

Subnet Mask

(Binary / Dotted Decimal)

Subnet Mask (Slash/ CIDR Notation)

Subnet Address #N Formula (N=0, 1, … # of Subnets-1)

0 (Default)

8

1

254

11111111.11111111.11111111.00000000

255.255.255.0

/24

—

1

7

2

126

11111111.11111111.11111111.10000000

255.255.255.128

/25

x.y.z.N*128

2

6

4

62

11111111.11111111.11111111.11000000

255.255.255.192

/26

x.y.z.N*64

3

5

8

30

11111111.11111111.11111111.11100000

255.255.255.224

/27

x.y.z.N*32

4

4

16

14

11111111.11111111.11111111.11110000

255.255.255.240

/28

x.y.z.N*16

5

3

32

6

11111111.11111111.11111111.11111000

255.255.255.248

/29

x.y.z.N*8

6

2

64

2

11111111.11111111.11111111.11111100

255.255.255.252

/30

x.y.z.N*4