416.6667 is the example result. A positive unit contribution is required to cover fixed cost. Fractional units describe the mathematical threshold; whole-item sales need rounding upward.
Estimate units needed to cover monthly fixed costs from selling price and variable cost. Include applicable fulfilment and selling fees in those inputs.
Protecting contribution before accepting a price
A positive unit contribution is required to cover fixed cost. Fractional units describe the mathematical threshold; whole-item sales need rounding upward. A quote can meet a revenue target and still leave too little to cover delivery. Separate the selling-price denominator from the cost denominator: margin and markup answer different questions. A discount changes contribution even when the supplier cost stays fixed.
What the model includes
Result = (([Monthly fixed costs]) ÷ ([Selling price per unit] − [Variable cost per unit])) A pricing review should retain the supplier cost, sale price and the reason for any allowance. Returns, payment charges, delivery and tax require explicit treatment; they should not disappear inside a percentage labelled profit. Compare the proposed price with the customer agreement and delivery capacity. A mathematically achievable margin does not establish that buyers will accept the offer.
Example with the supplied inputs
Monthly fixed costs: 5000; Selling price per unit: 30; Variable cost per unit: 18. Result: 416.6667. The values are illustrative.
Compare one changed input
Monthly fixed costs changes from 5000 to 5500. The result becomes 458.3333. All other inputs remain fixed.
Calculation rule
Result = (([Monthly fixed costs]) ÷ ([Selling price per unit] − [Variable cost per unit]))
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Monthly fixed costs | 5000 | Use monthly fixed costs on the currency and period basis shown by the formula. Keep gross amounts, net amounts and unit amounts distinct; the page does not fetch a price or exchange rate. |
| Selling price per unit | 30 | Use selling price per unit on the currency and period basis shown by the formula. Keep gross amounts, net amounts and unit amounts distinct; the page does not fetch a price or exchange rate. |
| Variable cost per unit | 18 | Use variable cost per unit on the currency and period basis shown by the formula. Keep gross amounts, net amounts and unit amounts distinct; the page does not fetch a price or exchange rate. |
Output: 416.6667 is the example result. A positive unit contribution is required to cover fixed cost. Fractional units describe the mathematical threshold; whole-item sales need rounding upward. Use the formula to distinguish a cash amount, count, percentage or ratio.
How to use the page
Collect the inputs
Gather Monthly fixed costs, Selling price per unit, Variable cost per unit. Use one period and the units shown in the form.
Run the calculation
Enter the values and select the action. The calculation rule above explains how the inputs produce the result.
Compare a scenario
Change Monthly fixed costs on its own, keeping the other inputs fixed. Read both results before changing another assumption.
Worked example
With the example inputs listed above, the result is 416.6667.
Change Monthly fixed costs from 5000 to 5500 while keeping every other value fixed. The result becomes 458.3333. This comparison isolates that input; it does not forecast how other variables will respond.
Check the stated formula, units and limits before using the result in a decision.
Keep the displayed formula, input units and model scope with the result. Corrections or questions can be sent through the request section on this page.
Content updated: October 11, 2026