10 units is the example result. The break-even quantity offsets an additional fixed purchasing cost with savings per unit from the supplied discount. It assumes the compared units would otherwise be bought at the undiscounted price.
The break-even quantity offsets an additional fixed purchasing cost with savings per unit from the supplied discount.
Protecting contribution before accepting a price
The break-even quantity offsets an additional fixed purchasing cost with savings per unit from the supplied discount. It assumes the compared units would otherwise be bought at the undiscounted price. 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 = round up([Additional fixed purchasing cost] ÷ ([Undiscounted unit purchase price] × [Supplier discount (%)] ÷ 100)) 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
Undiscounted unit purchase price: 100; Supplier discount (%): 20; Additional fixed purchasing cost: 200. Result: 10 units. The values are illustrative.
Compare one changed input
Undiscounted unit purchase price changes from 100 to 110. The result becomes 10 units. All other inputs remain fixed.
Calculation rule
Result = round up([Additional fixed purchasing cost] ÷ ([Undiscounted unit purchase price] × [Supplier discount (%)] ÷ 100))
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Undiscounted unit purchase price | 100 | Use undiscounted unit purchase price 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. |
| Supplier discount (%) | 20 | Enter supplier discount (%) on the percentage scale used in the formula (20 means 20%, not 0.20). Keep its base and reporting period consistent with the other inputs. |
| Additional fixed purchasing cost | 200 | Use additional fixed purchasing cost 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: 10 units is the example result. The break-even quantity offsets an additional fixed purchasing cost with savings per unit from the supplied discount. It assumes the compared units would otherwise be bought at the undiscounted price. Unit: units.
How to use the page
Collect the inputs
Gather Undiscounted unit purchase price, Supplier discount (%), Additional fixed purchasing cost. 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 Undiscounted unit purchase price 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 10 units.
Change Undiscounted unit purchase price from 100 to 110 while keeping every other value fixed. The result becomes 10 units. 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