Enter your normal price, your cost and the discount. You get the new margin and the extra sales you need just to stand still.
Margin after discount
Margin before
–
Extra sales needed
–
Fill in the boxes and press Calculate.
Full breakdown
Why discounts cost more than they look
A discount comes straight out of your profit, not out of your price as a whole. Your cost doesn't drop when you cut the price, so a 20% price cut can easily remove half of what you earn on each sale.
Example
A $100 jacket costs $60. Normally it earns $40, a 40% margin. At 20% off it sells for $80 and earns $20, a 25% margin.
Profit per jacket has halved, so you need to sell twice as many, 100% more, to make the same money. If the sale only lifts volume by 50%, you end up with less profit than if you'd done nothing.
extra sales needed = (old profit ÷ new profit − 1) × 100
How margin changes the picture
Extra sales needed to keep the same profit
Your margin
10% off
20% off
30% off
30%
50%
200%
impossible
40%
33.3%
100%
300%
50%
25%
66.7%
150%
60%
20%
50%
100%
A 30% discount on a 30% margin product leaves no profit at all, so no amount of extra sales can make it up. The lower your margin, the more careful you need to be with promotions.
Questions
How much more do I need to sell after a 20% discount?
It depends on your margin. At a 40% margin a 20% discount halves your profit per sale, so you need twice the sales (100% more) to earn the same. At a 60% margin you'd need 50% more.
What's the formula for extra sales needed?
Extra sales % = (old profit per unit ÷ new profit per unit − 1) × 100.
Is a discount ever worth it if I need more sales than that?
Sometimes, for reasons outside this sum: clearing old stock, winning customers who come back at full price, or selling add-ons with a higher margin. Just make the decision knowing what it costs.
Does this include payment or marketplace fees?
Add them to the cost. Percentage fees shrink a little when the price drops, so counting them at their full-price amount makes the result slightly cautious, which is the safe side to be on.