Costs, Revenues & Profits: The Basics

In this video I go through the definitions and formulas of the economic key terms total cost, variable cost, fixed cost, average cost,average variable cost, average fixed cost,marginal cost, marginal revenue, total revenue, average revenue, normal profit and supernormal profit.


The term equilibrium refers to the point at which demand = supply.

– It is believed that if you leave markets to their own devices, this will result in a market performing at an equilibrium level. This is based on the assumption that all other things are equal (Ceteris Paribus) such as that perfect competition exists in the market place.

– We can clearly see from any demand and supply diagram that if we operate at a price higher than the equilibrium price than this will result in excess supply. This is because if you look at the x-axis you can see that quantity supplied is greater than quantity demand. It is obvious from my other post that the reason for this is that as price increases less people are able  or willing to afford the good.

– Similarly, if a market operates at a price lower than that of the equilibrium price then this will result in excess demand. This is because again if we looked at a demand and supply diagram we can clearly see that the quantity demanded is greater than the quantity supplied. I can think of a great example to reflect this imbalance, when Topshop have a sale the price of their goods is reduced, the demand for sale products is great but the amount of goods that are available (the pretty ones that is) is very low. This results in people having their demand not met.

Important to note: That all movements along the curve are down to price changes. All shifts are down to non-price determinants such as weather, tastes, incomes, price of substitutes and complements etc.