A break-even number is more useful when the arithmetic around it remains visible. SBA’s calculator gives a single-product units formula: fixed costs divided by selling price minus variable cost per unit. The original fictional model below uses invented monetary units and constant assumptions. It is an arithmetic exercise, not a forecast, an actual business assessment or accounting or tax advice.
Declare the month and the three inputs
Imagine one product sold for 10 units of money each. Its declared variable cost is 4 per item, and its declared fixed cost for the same month is 150. Assume that every item made for this model is sold, the price stays unchanged and those are the complete modeled costs. These are invented conditions, not supplier quotes or findings about a real maker.
The subtraction 10 minus 4 leaves 6 per sold item to meet the monthly fixed amount. Divide 150 by 6: the break-even point is 25 sold items under these assumptions. The denominator needs to be positive for this particular calculation to give a meaningful positive units threshold. A real mixed-cost or multi-product situation needs a more appropriate analysis.
Check the line just below the threshold
At 24 sold items, revenue is 24 times 10, or 240. Variable cost is 24 times 4, or 96. Add the fixed 150 to that 96 and total modeled cost becomes 246. Revenue minus total modeled cost is negative 6. The same result comes from 24 contributions of 6, which provide 144 against a fixed 150.
That check explains the threshold rather than merely repeating its name. Twenty-four units have not met all the declared costs, even though each sale brings in more than its variable cost. The example does not establish cash timing, inventory funding or when a real bill must be paid.
Check the threshold and the next unit
At 25, revenue is 250, variable cost is 100 and total modeled cost is 250. The balance is zero. At 26, revenue is 260, variable cost is 104 and total modeled cost is 254, leaving a positive modeled balance of 6. These lines use the same month and assumptions as the initial division.
A positive modeled balance is not evidence that an actual owner has earned a particular wage or can withdraw that amount. If labor, fees or another real expense was omitted from the inputs, the model would need revision. The declared completeness is an assumption of the exercise, not permission to ignore a real cost.
Change the price and calculate again
Now change only the selling price to 9. The variable cost remains 4 and monthly fixed cost remains 150. Each sale now contributes 5, so 150 divided by 5 requires 30 items. At 25 items under this new price, revenue is 225 and total modeled cost is still 250: the balance is negative 25.
The comparison does not recommend the original price or the reduced one. It shows why a changed input requires another calculation. A simple notebook or spreadsheet can hold the complete lines before a paid planning tool is considered. Establish actual costs and demand separately, and seek appropriate professional help for the real financial decisions that this invented model cannot settle.
Sources & further reading
Published sources for the details and examples discussed in this story.
