Which metric matters first during a coupon campaign?

Start with net profit per unit at the discounted selling price, then confirm break-even ACOS. Discounts reduce both margin and ad tolerance.

Why can deal sales rise while profit falls?

Discounts compress contribution margin immediately while ads and return costs may stay high. If conversion lift is not enough, total profit rate declines.

Amazon Promotion

Amazon Coupon and Deal Margin Guide

Coupon campaigns and deal windows can lift click-through and conversion, but they also reduce realized selling price immediately. If you only watch unit sales, you can miss how fast contribution margin is shrinking.

A safer promotion model tracks two metrics together: net profit per unit at the discounted price, and break-even ACOS under the same assumptions. If both still hold, scaling promotion spend is usually safer.

Promotion Margin Formula

Discounted price = list price - coupon value - deal discount. Net profit per unit = discounted price - product cost - inbound freight - referral fee - FBA fulfillment - ad cost - return loss - other costs. Margin = net profit per unit / discounted price.

In promotion periods, coupon value should be treated as a direct unit-level cost, not just a branding budget. Lower realized price means ad ratio and break-even ACOS can deteriorate quickly.

Example Scenario

Assume list price 39.99 USD, coupon 6 USD, discounted price 33.99 USD. If product plus inbound cost is 13.5 USD, fees are 8.1 USD, ads are 4.2 USD, and return plus other costs are 2.1 USD, net profit is 6.09 USD per unit.

If ad cost rises to 6 USD per sold unit during the deal, your margin can drop sharply. At that point, either reduce discount depth, shorten campaign duration, or improve conversion before scaling bids.

Execution Checklist

Calculate margin from discounted price, not list price.
Recompute break-even ACOS for each promotion setup.
Stress-test model with a 1-2 point higher return rate.
Backfill with actual campaign data before repeating the offer.

Next Step

Run scenarios in the profit calculator, then validate fee completeness with Amazon FBA fees explained. For ad risk control, continue with the break-even ACOS guide and Amazon ACOS benchmark.