Discounts and promotions: avoiding the margin trap
How discounts quietly train customers to wait, what they do to margin, and the promotion patterns that grow a store instead of eroding it.
The short answer
A discount is paid on every sale it touches, including all the sales that would have happened at full price. Its only benefit is the extra sales it caused, and separating the two is the step that gets skipped, so they see a spike in revenue and a quiet decline in margin. Frequent sitewide discounts also teach customers to wait for the next one and reset the price they consider normal. The patterns that grow a store instead of eroding it are targeted and structural: a welcome offer for genuinely new customers, bundles and thresholds that raise order value, loyalty rewards after purchase rather than before, and clearance that is clearly clearance. Measure every promotion against a baseline period and against margin, never against the spike.
The margin arithmetic
| Without discount | With a sitewide discount | |
|---|---|---|
| Sales that would have happened anyway | Full margin | Reduced margin on every one |
| Extra sales caused by the discount | None | Reduced margin, but incremental |
| Sales pulled forward from next month | Next month’s revenue | This month’s revenue at lower margin, next month’s gap |
| Customer expectation | Price is the price | Wait for the next sale |
| Net effect | Baseline | Often lower total margin across the period |
Patterns that build instead of erode
- Welcome offer, single-use, new customers only, for the first order. Buys a relationship.
- Thresholds: free shipping or a gift above an order value set from margin. Raises average order.
- Bundles: products sold together at a price that reflects lower fulfilment cost. Raises order value without discounting the items.
- Loyalty after purchase: rewards for repeat customers, earned, not advertised on the homepage.
- Early access for subscribers to new products, instead of a coupon.
- Clearance, clearly labelled, in its own place, for end-of-line stock only.
- Rare, planned events where the whole market expects them, with margin calculated in advance.
Measuring a promotion honestly
Before: the average daily margin for a comparable period. During: margin, not revenue. After: the weeks following, to see the pull-forward dip. Where possible, a holdout: a group that did not receive the offer, for comparison. Then the question: did total margin across the whole period rise? If the answer is no, the promotion was expensive theatre, and the next one should be designed differently.
What this means for you
Treat every discount as a cost paid on every sale it touches, and measure its benefit as the incremental sales only, against margin, across the whole period. Prefer welcome offers, thresholds, bundles, loyalty after purchase and honest clearance over sitewide sales. A store that rarely discounts and does it deliberately keeps its prices credible and its margin intact, and that is what funds the next year’s growth.
Frequently asked questions
Our sales spike during discounts. Is that not proof they work?
It is proof that people buy when prices drop, including people who would have bought at full price next week. Compare the weeks before and after with the discount week: if the total across the period is similar and margin is lower, the discount moved sales rather than creating them. Measure the whole period and the margin, not the spike.
Should we offer a discount for newsletter sign-ups?
A first-order offer for genuinely new customers is one of the better uses of a discount: it is targeted, one-time, and buys a relationship. Make it single-use, new customers only, and watch for the same customers signing up repeatedly. Beyond that, the newsletter earns its keep with content and early access, not with a permanent coupon.
How do we clear old stock without training customers?
Call it clearance, put it in its own section, make it visibly end-of-line, and keep it away from the regular catalogue and the homepage. Customers understand that discontinued items are cheaper; what they learn from is regular products going on sale every month.
Sources
- Shopify Help Center: Discounts (accessed 2026-09-12)