A promotion increases orders, and the advertising team calls it a success. The business owner sees a different result: lower contribution per order, more fulfillment work, and little improvement in the amount left after media costs.
Before increasing spend, model what the discount does to the unit economics. Then define the customer-response improvement the promotion would need to justify the additional activity.
Calculate the new revenue amount
Start with the actual price customers will pay after the discount, including the offer's eligibility and stacking rules. Use a revenue definition consistent with the business's margin model.
Do not subtract a percentage from a gross checkout total if the offer applies only to selected merchandise. Shipping, tax, bundles, and excluded products can change the effective order-level discount.
Test the offer in the approved QA environment. A spreadsheet assumption about the price is not enough if the checkout applies the code differently.
Recalculate variable costs
Some costs remain nearly unchanged when price falls, such as product cost and much of fulfillment. Others may vary with revenue, order size, shipping method, or return behavior.
The SBA's break-even guide provides a basic reference for the relationship between selling price, variable costs, and contribution. Apply it using the costs relevant to the actual promotion.
Check the coverage of source reports. Shopify's profit-report documentation explains its recorded product-cost basis; that is not automatically the complete cost of fulfilling and acquiring a promotional order.
Work through a contribution example
Suppose an illustrative product sells for $100 and has $55 of included non-ad variable costs. Contribution before advertising is $45. A 20% price discount lowers revenue to $80. If the included costs remain $55 for this simplified example, contribution falls to $25.
The price declined by 20%, but contribution declined by about 44%. To generate the same $4,500 of pre-ad contribution as 100 full-price orders, the business would need 180 discounted orders at $25 contribution each.
This is contribution arithmetic, not a prediction that the discount will create that volume. Real costs and customer behavior may differ from the simplified assumptions.
Include advertising cost in the comparison
| Illustrative result | Regular offer | Discounted offer |
|---|---|---|
| Revenue per order | $100 | $80 |
| Non-ad variable cost | $55 | $55 |
| Contribution before ads | $45 | $25 |
| Media cost per order | $20 | $15 |
| Contribution after media | $25 | $10 |
In this example, the promotion lowers media cost per order but still leaves much less contribution per order. The business would need enough additional volume to make the total result worthwhile, while accounting for other costs and capacity.
Do not celebrate a lower CPA without checking the contribution it purchases.
Define the required customer-response change
Estimate the conversion, order-value, or acquisition-cost improvement needed under the proposed traffic plan. Keep the calculation tied to explicit assumptions about click cost, customer mix, and order economics.
A conversion-rate increase can reduce cost per order if click costs and the relevant traffic conditions remain comparable. If those conditions also change, the relationship needs to be recalculated.
Show conservative and optimistic cases rather than one precise uplift assumption. A promotion whose economics work only under an unusually strong response needs a more cautious commitment.
Consider customer and product mix
A discount may attract different buyers or shift orders toward different products. New-customer share, repeat behavior, returns, and bundle composition can all affect the eventual result.
Do not assume promotional customers have the same retention as regular-price customers. Follow cohorts where the data allows it, and label future value estimates separately from realized contribution.
Also inspect whether the offer subsidizes purchases that would likely have occurred anyway. Ordinary attribution does not resolve that incremental-demand question.
Separate the offer test from the creative test
If the promotion launches with a new visual concept, the result concerns both changes. Use the offer-versus-visual guide to choose a design that matches the question.
The business may simply need to evaluate the whole promotional package. That is acceptable if the conclusion stays at that level. Do not use the result to claim a permanent creative rule when the discount may have driven the response.
Keep the destination, offer terms, and actual served assets in the record so the test can be reconstructed.
Coordinate bidding and budget controls
Use the seasonality-versus-budget guide when preparing Google Ads for an unusual promotion. An expected conversion-rate change and an approved spending increase are different assumptions.
Keep the media plan within the contribution and cash boundaries the business accepted. A platform recommendation to increase spend does not establish that the discounted orders support that increase economically.
Monitor inventory and service capacity as well as advertising response. A promotion that creates unfulfillable orders can introduce costs absent from the initial model.
Plan the expiration and later review
Use the promotion expiry checklist to coordinate codes, ads, feeds, and landing pages. Confirm the final state rather than assuming every schedule completed correctly.
After outcomes mature, compare actual price, volume, acquisition cost, returns, and contribution with the original assumptions. Preserve the initial projection so the team can improve future planning.
The promotion should be judged by the business result it was intended to produce. More orders or a higher conversion rate can be useful evidence, but the model shows what those changes need to contribute before the company commits more advertising spend.