Ecommerce & Shopify · 100% free

Discount Impact Calculator

See how much margin a 10/20/30% discount eats, and how many extra units you'd need to break even.

Shopify WooCommerce Any retailer
At 20% off, you'd need this volume lift to break even
+57%
That's 1,567 units vs 1,000
DiscountSale priceContribution/unitUnits to break evenVolume lift needed
10%$76.50$38.501,221+22%
15%$72.25$34.251,373+37%
20%$68.00$30.001,567+57%
25%$63.75$25.751,826+83%
30%$59.50$21.502,187+119%
40%$51.00$13.003,616+262%
50%$42.50$4.5010,445+944%
Reality check: the average ecommerce promo lifts unit volume 15–35% during the promo window — and that lift often pulls forward sales from next month. If you'd need a 60%+ lift to break even, the discount is almost certainly losing you money. Baseline contribution: $47,000. Required lift at this discount: 57%.

About this tool

Every founder under-estimates how much margin a discount eats. A 30% discount on a 40% margin product cuts your contribution by 75%. This tool shows the real margin hit per discount tier, and how much unit-volume uplift you'd need to come out flat.

Why discounts are sneaky-expensive

A 30% discount feels like a 30% margin hit. It isn't. On a $50 product with $30 cost, full-price contribution is $20. At 30% off ($35 sale price), contribution drops to $5 — a 75% cut to margin. To break even on contribution you'd need to sell 4× as many units. Most promos lift volume 15–35%.

When discounts work anyway

  • • Clearing dead stock — contribution > 0 beats writing it off
  • • Acquisition campaigns where first-purchase LTV justifies first-order loss
  • • Bundle / threshold discounts (less margin damage per dollar discounted)
  • • Loyalty tier rewards — discount tied to retention behaviour

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