Give each cost the right job
A fixed cost stays the same over the range of sales being modelled: imagine 24 coins to set up a pretend stall for one round. A variable cost changes with each item made: perhaps 5 coins for its ingredients. These labels describe a particular model and time period; they are not permanent properties of a cost.
If an item sells for 8 coins and costs 5 coins to make, it contributes 3 coins toward the fixed cost and then profit. Keeping all 8 coins as “profit” would forget the ingredients. Subtracting the setup cost from every individual item would count that one cost repeatedly.
A round with a 24-coin setup cost
The contribution per item is 8 − 5 = 3 coins. Divide the fixed cost by this contribution: 24 ÷ 3 = 8 items. At eight sales, revenue is 64 coins; total cost is 24 + (8 × 5) = 64 coins. Profit is zero.
| Items sold | Revenue | Total cost | Result |
|---|---|---|---|
| 7 | 56 | 59 | 3-coin loss |
| 8 | 64 | 64 | Break-even |
| 9 | 72 | 69 | 3-coin profit |
Some settings never reach break-even
If price equals variable cost, sales contribute nothing toward a positive fixed cost. Selling more cannot pay it off. If price is below variable cost, each additional sale makes this model’s result worse. Do not divide by zero or report a negative sales target as a useful break-even point.
When the result is fractional, whole items matter. With a 25-coin setup cost and 3-coin contribution, the exact threshold is 8⅓ items. You cannot sell a third of an indivisible item, so nine is the first whole-item quantity with no loss. That is different from claiming nine gives exactly zero profit.
Use the distinction in Monster Market
In Monster Market, compare the costs and sales feedback the game actually shows. Before a round, explain whether you are testing price, quantity or a purchase choice. Afterward, ask which coins were revenue and which remained after the recorded costs. Follow the mission’s specific goal as well as the total.
This page assumes every item produced is sold at one price. An actual round can involve a different inventory or recipe model. Unsold stock, waste, time and additional fees can change the result. Use the calculation to understand the distinction between contribution and profit; do not copy its numbers as a guaranteed game strategy or a real business forecast.
Source & scope
OpenStax: Calculate a Break-Even Point in Units and Dollars. Reference for contribution-based break-even analysis. The fictional stall and coin amounts are original educational examples.
This is an Aurism learning article, with AI-assisted development as described in our editorial approach. It does not claim an independent expert review or that a simplified model reproduces every game outcome. Report a correction.
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Monster Market
Use the mission’s actual instructions and feedback to test your next prediction.