There are total of 16 squares.

How?

Lets count…
Squares with side length equal to 1 match stick: 9
Squares with side length equal to 2 match sticks: 5(2+1+2)
Square with side length equal to 3 match sticks: 1 (This is difficult to find, and easy to miss)
Square with side length equal to 4 match sticks: 1 (Everybody knows)
So total number of squares : 16