What does that discount really cost you?

Why break-even ROAS matters

Break-even ROAS = selling price ÷ contribution margin (price minus product, shipping, and fee costs). If your ads run below it, every "sale" loses money regardless of what Ads Manager celebrates. Most stores discover their break-even ROAS is higher than they assumed, especially during discount events. More on reading your blended numbers in the KPIs I actually track.

What a discount actually costs

A discount does not reduce revenue by the discount percentage. It reduces profit by considerably more, because your costs do not move when your price does. Product cost, pick and pack, shipping, and payment fees are all unchanged. The entire discount comes out of the margin.

Take a $59 product costing $18, with $6.50 shipping, $12 marketing per order, and 2.9 percent payment fees.

A 20 percent discount cut profit by 55 percent. That is the number that matters, and it is the reason a sale can grow revenue while shrinking the business. To earn the same total profit you now need more than twice the order volume, and every one of those extra orders carries its own shipping and marketing cost.

Break-even ROAS is the number to watch

Break-even ROAS tells you what your advertising must return simply to avoid losing money:

Contribution margin = price - product cost - shipping - fees
Break-even ROAS     = price / contribution margin

At full price that product contributes $32.79 on $59, so break-even ROAS is about 1.8. At 20 percent off it contributes $21.33 on $47.20, so break-even ROAS climbs to about 2.2.

Which means a discount quietly raises the bar your ads have to clear, at exactly the moment you are most likely to increase spend. Campaigns that were comfortably profitable at 2.0 ROAS start losing money during the sale, and the platform reports the sale as a success because platform ROAS does not know your margins.

Discounting is not the only lever

Discounts are the fastest way to move volume and the most expensive. Before defaulting to one:

• Bundles raise order value instead of cutting unit price, so the shipping and marketing cost per order is spread across more revenue.
• Free shipping thresholds cost you a fixed amount and push order value upward rather than downward. Size it with the threshold calculator.
• Gift with purchase costs you the item's cost, not its retail price, which is usually a fraction of an equivalent discount.
• Tiered discounts such as spend more save more attach the discount to higher order values, so the margin sacrificed buys something.

When discounting is the right call

It genuinely is, sometimes. Clearing seasonal or dated inventory before it is written off entirely. Acquiring a first order for a product with strong repeat purchase behaviour, where the lifetime value justifies losing money on order one. Hitting a volume commitment that unlocks better supplier pricing. Testing price sensitivity before a permanent change.

The distinction is whether you are discounting toward a known objective with a number attached, or discounting because revenue is soft this month and it is the easiest lever to reach. The first is strategy. The second is a habit that resets what customers believe your product is worth.