# Short Run Production Costs

8 Jul

Production information must contain resource prices in order to determine total and per unit price of diverse amount of output. It’s known that in short run prices are associated with plant’s variable resources. Its capital resources are limited so we shouldn’t consider them. Short run costs can be either variable or fixed. So let’s describe them:
Fixed Cost: these costs don’t vary with changes in output. These costs must be paid even if the firm doesn’t produce anything. Such costs may be: rental payments, interests of firm’s debts, money paid for insurance. These costs are paid even when the firm has zero output, so firm can’t avoid paying these costs.
Variable Cost:
These costs vary with the change in output. They include payment for raw material, fuel, wages, transportation prices, fuel etc. These payments vary directly with output. As the production begins variable costs will increase by a decreasing amount, but after a point they will rise by an increasing amounts (as a result of law of diminishing marginal returns) also this reason lies in the shape of Marginal Product (MP) curve, which is increasing with smaller and smaller amounts and when diminishing returns are encountered marginal product begin to decline, so larger and larger amounts of variable resources are needed to produce a successive unit of output. Total variable cost then is increasing by an increasing amount.
Total Cost:
Economists call sum of fixed costs and variable costs as total costs. At zero unit of output total costs are equal with fixed costs. Graphically, amount of vertical Total Fixed Cost (TFC) summed with vertical value of Total Variable Cost (TVC) should result in Total Cost (TC).
For business manager these distinctions between fixed and variable costs are very important. Variable costs can be controlled or changed by changing production levels in short-run. However, fixed costs are beyond control of business manager, because they are included in short run and must be paid regardless the output level. In short run firms can’t get out of industry and leave the market.

Per-unit and Average Costs:
Average fixed cost (AFC) is found by dividing total fixed cost by output quantity (Q):

Because Total fixed Cost by definition is the same regardless of output, then AFC curve will decline as output increases,because as output quantity increases Total Fixed Cost (TFC) is spread over a larger output produced. Q≠0.

Average Variable Cost (AVC): for any output quantity (Q≠0) is calculated by dividing Total Variable Cost (TVC) by Quantity output (Q):

As added more variable resources increase output, average variable cost (AVC) declines initially, reach a minimum and then increases again, so AVC curve is U shaped. It can be explained by the fact that AVC (also TVC) curve reflects law of diminishing returns.

To explain in simple terms, at very low levels of output, production is inefficient because of high-costs and low quantity produced. Initially, since firm is understaffed, average variable cost is relatively high. As output expands greater level of specialization, greater division of labor and better use of firm’s capital occurs. However, when we still add more variable resources, a point is reached when diminishing returns are incurred. Also the firm is being overstaffed so each additional unit of variable resource doesn’t increase marginal product (MP) as before.

ATC
Average Total Cost (ATC) for any output level is found by dividing Total Cost (TC) by output (Q) or by adding average variable cost (AVC) and average fixed cost (AFC):

Graphically ATC can be found by adding vertically average variable cost (AVC) and average fixed cost (AFC). Q≠0.

Marginal Cost
Marginal Cost is the additional cost of producing one more unit of output. Marginal cost can be found by following formula:

Marginal Cost is important for firm’s managers because a firm can control it immediately. It is used to find the cost of production of an additional product, so it helps to save some money if the firm doesn’t produce this unit (because of the loss that may occur at production).