Marginal Cost Calculator
Find the marginal cost — the extra cost of producing each additional unit — by entering total costs and output quantities at two production levels.
units
units
Average additional cost of producing one more unit between the two output levels
- 1
Change in total cost (ΔTC)
13,500 − 10,000 = 3,500 - 2
Change in quantity (ΔQ)
150 − 100 = 50 - 3
Marginal cost
3,500 ÷ 50 = 70Extra cost of producing one more unit between the two output levels.
How does this calculator work?
Marginal cost = (TC₂ − TC₁) ÷ (Q₂ − Q₁). It measures the extra cost of producing one more unit between two output levels. Firms maximise profit where MC equals the market price (price-takers) or marginal revenue (price-setters). Enter costs and quantities at two production points to calculate it.
Formula
How this is calculated
Marginal cost (MC) is the change in total production cost that arises when one additional unit of output is produced. Mathematically it is the first derivative of the total cost function with respect to quantity, but in practice it is approximated between two observed data points: MC = (TC₂ − TC₁) ÷ (Q₂ − Q₁). Enter the total cost and quantity at two different production levels and the calculator gives the average marginal cost over that range.
Understanding marginal cost is central to profit-maximising pricing decisions. In competitive markets firms maximise profit where marginal cost equals marginal revenue — the MC = MR rule. If the price received for an extra unit exceeds the marginal cost of producing it, producing more increases profit; if marginal cost exceeds the price, reducing output increases profit.
The calculator also shows the average cost per unit at each quantity level for comparison. Note that MC calculated between two discrete data points is an average over the range, not the true instantaneous marginal cost. Real marginal cost curves are often U-shaped — falling with economies of scale, then rising as capacity constraints appear — but this calculator estimates the linear segment between the two points you provide.
Frequently asked questions
The fundamental profit-maximising rule is to produce until marginal cost equals marginal revenue (the market price in a competitive market). Setting a price below marginal cost means each additional unit sold reduces profit. Understanding MC helps set price floors and evaluate whether to accept bulk or discounted orders.
When marginal cost is below average cost, producing more units lowers the average cost (economies of scale). When marginal cost rises above average cost, the average begins to increase. The two curves always cross at the minimum of the average cost curve.
A negative marginal cost (TC falls as output rises) can occur in industries with network effects or digital goods (near-zero reproduction cost), or it may indicate a data entry error. Physical manufacturing almost always has positive marginal costs.
TG we-Calculate Editorial Team. (2026). Marginal Cost Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/marginal-cost-calculator
TG we-Calculate Editorial Team. "Marginal Cost Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/marginal-cost-calculator.
TG we-Calculate Editorial Team, "Marginal Cost Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/marginal-cost-calculator
@misc{wecalculate_marginal_cost_calculator, title = {Marginal Cost Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/marginal-cost-calculator}}, year = {2026}, note = {TG we-Calculate} }
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