Cart Sheets / Free guides
Will your Black Friday discount lose money? A simple margin check
A discount that looks generous can quietly wipe out your profit once shipping and fees come off. It takes five minutes to check each offer.
The formula
Profit per unit = price − unit cost − shipping and packing − payment fees
Payment fees are usually a percentage of the price plus a fixed amount per order. Use your own rates from your payment provider.
A worked example
These figures are made up to show the maths. Price €40, unit cost €14, shipping and packing €6, payment fees 2.9% + €0.30.
| Full price | 25% off | 40% off | |
|---|---|---|---|
| Sale price | €40.00 | €30.00 | €24.00 |
| Unit cost | €14.00 | €14.00 | €14.00 |
| Shipping and packing | €6.00 | €6.00 | €6.00 |
| Payment fees | €1.46 | €1.17 | €1.00 |
| Profit per unit | €18.54 | €8.83 | €3.00 |
| Units needed to earn the same | 1 | about 2.1 | about 6.2 |
In this example, 25% off means selling about twice as many units just to stand still. At 40% off you would need more than six times as many. The break-even price, where profit hits zero, is about €20.91.
Free template: offer margin check
| Offer | Price | Discount % | Sale price | Unit cost | Shipping and packing | Fees | Profit per unit |
|---|---|---|---|---|---|---|---|
Spreadsheet formulas
| Cell | What | Formula |
|---|---|---|
| B1 | Price | your number |
| B2 | Unit cost | your number |
| B3 | Shipping and packing | your number |
| B4 | Fee % | for example 2.9% |
| B5 | Fixed fee | for example 0.30 |
| B6 | Discount % | for example 25% |
| B7 | Sale price | =B1*(1-B6) |
| B8 | Profit at full price | =B1-B2-B3-B1*B4-B5 |
| B9 | Profit on sale | =B7-B2-B3-B7*B4-B5 |
| B10 | Units needed to earn the same | =B8/B9 |
This is a planning check using your own numbers. It does not predict sales.