1. Total product (TP): It refers to the aggregate output produced with the help of factor inputs during a particular period of time. It is obtained by adding the marginal product contributed by each input. For example, combination of 2 factors used to produce output is added to find the total product. Suppose factor 2 is fixed at 4 units where factor 2 takes the value of 4 and so on. 

TP = ΣMP, where Σ is the summation, MP is marginal product.

2. Average product (AP): Average product is an unit of output which is produced per unit input. It is calculated by dividing the total product with the help of variable inputs. 

AP = TP/L where TP is total product and L is the variable factor input (e.g. labour)

For instance, to produce 50 units of shirts, 5 labourers are used. Here the average product of each variable input, i.e. labour is as follows:

AP = TP/L = 50/5 = 10 units.

3. Marginal product (MP): Marginal product refers to additional unit of output produced with the help of additional unit of input of labour or capital. In other words, marginal product of an input is defined as the change in output per unit of change in one of the inputs when all the other inputs are held constant. We can calculate MP with the help of following formula:

MP = TP_n – TP_n-1 or MP = Change in output(Δq)/Change in input(ΔL)

Where, MP is marginal product, TP_n is total product of ‘n’ units and TP_n-1 is total product of previous unit of output. For example, if five units of labour one used to produce 25 shirts and 6 labourers are used to produce 28 shirts the marginal product is 3 shirts (28 – 25 = 3).