Average Cost and Marginal Cost Calculator

Problem → model → reason → result

What problem does this model solve?

Calculate total, average fixed, average variable, average total and marginal cost from two output observations.

Why does the model apply?

Fixed cost does not change between the observations, so the change in total cost equals the change in variable cost. Marginal cost is estimated over the output interval.

What assumptions does it make?

The variables must describe the same market, firm, period or decision context and use consistent units. Any behavioural condition implied by the formula—such as other factors remaining unchanged—must be reasonable for the question being asked.

Formula

ATC = (FC + VC) ÷ Q; AFC = FC ÷ Q; AVC = VC ÷ Q; MC = ΔVC ÷ ΔQ

Calculation and working

The calculator substitutes your inputs locally and displays the numerical result. Change one input at a time to test which relationship drives the result.

What does the result mean?

Interpret the result in the economic context named above, including its sign, magnitude, units and time period. A calculated relationship is not by itself evidence that one variable caused another.

Worked example

With $1,000 fixed cost, variable cost rising from $2,000 at 100 units to $2,500 at 120 units, new ATC is $29.17 and marginal cost is $25.

When does this model not apply?

Do not use the result when the input definitions, units or formula assumptions do not match the real situation. This is an educational model, not financial, investment, tax or policy advice; verify material decisions against primary data and professional guidance.