difference between average cost and marginal cost

Difference between MC and AC:

1. Marginal cost refers to addition to total cost when more unit of output is produced whereas average cost refers to per unit total cost of production.

2. Marginal cost is calculated by the formula:
MCn = TCn - TCn-1
Average cost is calculated by the formula:
AC = TC ÷ Q

3. MC is independent of AC, i.e. It's the MC curve which pulls the AC curve downwards or upwards, whereas AC depends on MC.