The report says every advertising dollar generated four dollars in sales. Good news? Perhaps—but what remains after product costs, delivery, payment processing and returns? ROAS compares revenue with ad spend, not profit with all costs. It cannot answer that question on its own.
Before asking for more budget, build a simple calculation with the client. Google’s ROI guidance considers profit and costs. The figures below are our own illustration, not a performance benchmark or financial recommendation for a particular business. [1]
1. Agree what goes into one order
Start with net revenue from a completed order. Define how discounts, refunds and relevant taxes are treated, then subtract product, fulfillment, payment and other variable costs. What remains is the order’s contribution before advertising—the meaning of contribution margin used here.
Keep this separate from final profit after fixed costs. Agree how agency fees enter the calculation so they are not deducted twice, once under acquisition and again under operations. Compare figures in the same currency and period.
2. Calculate a CPA that fits this model
CPA is the average cost of the action being measured, such as a purchase or an inquiry. Always name the action: the cost of a form submission is not the cost of acquiring a paying customer.
In this simplified order model, subtract the amount you want to retain after advertising from contribution before advertising. The result is your target CPA under those assumptions. It does not mean the platform can achieve it; it shows the cost the business could accept.
Worked example: where does a $30 target come from?
These hypothetical figures are not service prices or client results.
| Per-order item | Illustrative amount |
|---|---|
| Net revenue | 100 USD |
| Product, fulfillment, payment and other variable costs | 55 USD |
| Contribution before advertising | 45 USD |
| Desired contribution after advertising | 15 USD |
| Target CPA under this model | 30 USD |
| Corresponding ROAS using the same revenue | 100 ÷ 30 ≈ 3.33 |
There is $45 left before advertising. Retaining $15 leaves $30 available for ads, corresponding to roughly 3.33 ROAS on the same revenue basis.
If variable costs rise to $65, only $20 is available for advertising and the corresponding ROAS becomes 5. Business requirements have changed even if the campaign has not. In the first scenario, a $45 CPA leaves no order contribution after advertising, before fixed costs.
3. Do not treat LTV as cash available today
LTV estimates customer value over their relationship with the business; its meaning depends on the calculation. State whether you mean revenue or contribution and which period you studied. Separate actual repeat purchases from a customer group with completed follow-up from forecasts that have not materialized.
Discuss collection timing too. A business may accept an acquisition cost over the long term while still needing to finance orders now. Review assumptions with finance rather than filling missing returns or repeat-purchase data with convenient guesses.
4. Make budget increases reviewable
Use a worksheet with definitions, calculations and the source of each number. Before proposing an increase, check changes in product mix, markets and order quality. A healthy past average does not establish the profitability of the next advertising dollar.
Record what needs monitoring after the increase and who will review it. The budget discussion can then focus on what the business keeps, rather than an attractive dashboard number alone.
Official sources
Source documentation reviewed: 16 October 2026. Features and eligibility may change; check the linked documentation before implementation.
