Free Discount Math Tool

That 20% off costs more than 20%

Your product cost doesn’t drop when you discount, so every point off the price comes straight out of profit. The real question is how many extra units you have to sell just to land back where you started. Most stores have never run that number. Here it is.

30 seconds to run 2 inputs Break-even volume included
Free Tool

Example

50% margin, 20% off.

Margin after discount30%
Profit lost per order$13
Extra units to break even+67%
The discount reflex

A discount is the easiest sale to make and the easiest profit to lose

On a 40% margin, a 20% discount means you have to sell twice as many units just to make the same profit. A 30% discount means four times as many.

You run a sale, revenue spikes, and somehow the month is less profitable.

A standing discount code trains customers to never pay full price.

You stack a promo on a thin-margin product and quietly sell it at a loss.

You judge a sale by units moved, not profit kept.

You match a competitor’s discount without knowing if your margin can take it.

You’ve never calculated the extra volume a discount actually requires.

Run the numbers

What your discount really costs

Two numbers tell you the core answer. Add your order value and volume to see the profit cost in dollars.

Profit as a share of price after product cost. If a $100 item costs you $50, your margin is 50%.
%
The percentage off the price.
%
To see the dollar cost per order.
$
To see the monthly profit given up.

Enter a margin and discount each between 1 and 99%.

Your result is ready

To break even on this discount you need to sell 0% more units.

Get the full picture.

Enter your name and email to reveal the rest on this page: your margin after the discount, the profit given up per order, the monthly total, and whether the discount is even profitable. You’ll also get my weekly newsletter on protecting margin. Unsubscribe anytime.

Get ecommerce insights worth opening

Useful strategies, quick audits, and real fixes to help you grow without wasting time or budget.

No spam. The newsletter is weekly and easy to leave.

+0%
more units you must sell just to break even on this discount
Margin after discount
0%
down from your starting margin
Profit lost / order
$0
at the same volume
Break-even multiple
0x
units vs your normal volume

Before you hit publish on that promo

  • Decide the goal first: clear stock, acquire a customer, or hit a tier. “Boost sales” is not a goal.
  • Protect thin-margin products. Exclude them from blanket codes.
  • Prefer a free gift or threshold offer over a percentage off when you can. It often costs less margin for the same nudge.
  • If repeat purchase value is high, a discount that loses on order one can still win on the customer. Know which case you’re in.
Check my full margin →

Formula: extra volume to hold profit = margin ÷ (margin − discount) − 1; profit given up per order = AOV × discount. Verified against standard retail break-even examples (a 20% discount on a 40% margin requires 2× the volume). Results are estimates based on the numbers you enter.

When discounting is a symptom, not a strategy

If you’re discounting to force conversions, fix the conversion instead

A lot of habitual discounting is really a patch over a store that doesn’t convert at full price. The Conversion Sprint finds why people hesitate and removes it, so you sell more without giving margin away. 14 days. Fixed price.

14-day delivery From $3,500 Shopify, Woo, Wix No retainer trap
See the Conversion Sprint
Jenn Velez – Founder, Ecomm Decoded
Built by an operator, not a marketer

I’ve watched a “great sale” quietly erase a month of profit.

I spent 10+ years inside ecommerce operations, including the merchandising calendar where discounts get decided. The pattern is always the same: people measure the sale by revenue and units, never by profit kept and the volume it actually demanded.

This tool puts the break-even volume in front of you before you commit, so a discount stays a decision and not a reflex.

Jenn Velez · Founder, Ecomm Decoded

Discount math, answered

FAQ

Divide your gross margin by your margin after the discount. On a 40% margin, a 20% discount drops you to 20%, so 40 / 20 = 2. You must sell twice the units to make the same total profit. A 30% discount on that margin needs four times the volume.
Yes. Your product cost doesn’t change when you discount, so every dollar off the price is a dollar off profit on that order. A 20% discount on a $65 order is $13 of profit gone per order, before you account for the extra volume needed to recover it.
When the discount percentage is bigger than your gross margin percentage. If your margin is 35% and you run 40% off, each unit now sells for less than it cost you. Volume can’t fix that. The more you sell, the more you lose.
Yes. No credit card. You give me your email, you get the full breakdown plus a weekly note on protecting margin. If you want me to fix the conversion problem behind habitual discounting, the Conversion Sprint exists for that, starting at $3,500. It is not required.

Counting on ads to move discounted stock? Check your ROAS floor.

The Break-Even ROAS Calculator shows the minimum return your ads need before they make money.

Run the Break-Even ROAS Calculator →