ADVERTISING ECONOMICS · FIRST-ORDER ACQUISITION
Maximum allowable CPA:
what can an order support?
For a first-order model, break-even advertising cost per order equals the order’s contribution before ads. A target cost per order is lower: subtract the contribution you want left after advertising.
If an order leaves €40 after variable costs and you want €15 left after ads, your target advertising cost per order is €25. That is a business threshold. The CPA reported in an ad account tells you what you spent, not what you can afford.
Understand the numbers ↓AdsMath basic metrics check · First-order economics
Illustrative €100 order
€25
Contribution before ads€40
Desired amount left€15
Break-even cost per order€40
Your target is below break-even.
Before fixed overhead and taxes. Illustrative figures.01 / The economics
Start with contribution, not revenue
Use average order revenue after discounts and refunds, on a consistent tax basis. Subtract variable costs such as product cost, shipping paid by the business, packaging, payment fees and expected return-handling costs. Do not deduct a refund twice: if it already reduces revenue, it should not also appear as the same cost.
The calculationContribution before ads per order = average order revenue − variable costs per order
Break-even cost per order = contribution before ads per order
Target cost per order = contribution before ads − desired contribution after ads
Break-even cost per order = contribution before ads per order
Target cost per order = contribution before ads − desired contribution after ads
02 / A worked example
A worked example
| Item | Per order |
|---|---|
| Average order revenue | €100 |
| Product, fulfilment and other variable costs | €60 |
| Contribution before ads | €40 |
| Desired contribution after ads | €15 |
| Target cost per order | €25 |
| First-order break-even cost per order | €40 |
At €25 cost per order, €15 remains. At €35, €5 remains: positive, but below the target. At €45, the first order is €5 short before fixed costs and taxes. Spending up to break-even leaves nothing from that order for overhead.
03 / Read the numbers
Compare the threshold with your traffic economics
When clicks and orders describe the same population, modeled cost per order is CPC divided by click-to-order conversion rate expressed as a decimal. At €0.75 CPC and 3% conversion, modeled cost per order is €25: €0.75 ÷ 0.03.
This is a scenario, not a forecast. A higher budget may change traffic cost, conversion and order mix. Test the assumptions against actual results.
04 / Scope and assumptions
CPA and CAC are not automatically the same
Ad spend divided by all attributed orders gives advertising cost per order. Customer acquisition cost needs new-customer counts and a clear definition of included acquisition costs. Repeat orders and non-ad acquisition expenses can make these figures different.
Scope: This model uses first-order contribution. It does not establish net profit, cash availability or lifetime value. If you justify a higher acquisition cost through repeat purchases, use measured cohort contribution and payback evidence rather than assumed future revenue. A negative target means the selected order economics cannot support that desired contribution even before advertising.
05 / The next decision
What should you change first?
Compare the gap between current and target cost per order. Then model one change at a time: lower CPC, higher conversion, a different order value or lower variable costs. A larger order only helps if its extra costs do not consume the additional contribution.
Put the assumptions together with AdsMath
AdsMath by ScalingROAS combines an advertising economics Simulator with a Decision Guide PDF. Explore how traffic cost, conversion rate, order value and contribution margin affect modeled cost per order and what remains after ads.
€49 one-time. No subscription.
Explore AdsMath Simulator + Decision GuideNeed only ROAS, cost per order and average order value? Use the basic campaign metrics calculator. It does not calculate allowable CPA or contribution after ads.
