Should the advertising budget increase?
An established online store is considering a budget increase after a stronger platform return. The latest week looks better inside the ad account: attributed revenue has risen faster than spend. Store-level economics tell a less comfortable story.
The decision in this fictional scenario is whether to raise total spend from €12,500. The team has two comparable seven-day windows, store revenue, a variable-cost estimate and a fee model. It does not yet have mature return data or a controlled estimate of incremental sales.
Keep the metric definitions separate.
| Input or metric | 5–11 Oct 2026 | 12–18 Oct 2026 |
|---|---|---|
| Advertising spend | €10,000 | €12,500 |
| Platform-attributed revenue | €34,000 | €45,000 |
| Platform ROAS | 3.40× | 3.60× |
| Store net revenue | €36,000 | €42,000 |
| Variable operating costs | €18,000 | €22,260 |
| Contribution margin before ads | 50% | 47% |
| Illustrative management fee · 10% of spend | €1,000 | €1,250 |
| Contribution after ads and fee, before overhead | €7,000 | €5,990 |
| Store net revenue ÷ ad spend | 3.60× | 3.36× |
Store net revenue excludes tax and reflects discounts and refunds recorded during the reporting window. Variable costs represent product, fulfilment, shipping, processing and return-related operating costs; refunded revenue is not deducted twice. Fixed overhead and corporate taxes are excluded.
Platform-attributed revenue follows the advertising platform’s attribution definition. It is kept separate from store revenue. Differences can reflect reporting windows, attribution rules or customer behaviour; the numbers alone do not establish the cause.
€42,000 − €22,260 − €12,500 − €1,250 = €5,990
Contribution after advertising and the illustrative management fee, before fixed overhead and tax.Store net revenue rose 16.7% and spend rose 25%. Contribution fell by €1,010, or 14.4%. The arithmetic identifies a deterioration in the illustrated economics; it does not prove that higher spend caused it.
Hold the envelope. Investigate the change.
Keep the weekly budget at €12,500.
Reallocate only within the approved envelope while investigating the deterioration. Do not infer that every campaign needs the same action.
What to investigate first
Reconcile reporting periods and refunds. Break variable costs down by product and market. Check whether discounts, shipping subsidies or product mix explain the margin movement. Review new-customer and returning-customer cohorts where the underlying data supports that distinction.
What can continue
Use the existing test budget to compare a small number of documented creative hypotheses. Record the audience, offer, landing page and reporting period. Keep a change log so a later review can distinguish the tests from unrelated commercial changes.
What would change the recommendation
A reconciled cost base and evidence that additional demand can contribute acceptably at the margin could support a controlled increase. Set the spend limit, review window and stop condition before the test. A useful trigger is a deterioration against the business’s agreed contribution threshold; that threshold must come from its economics.
Change an assumption. See the consequence.
This calculator keeps the model deliberately narrow. It evaluates an assumed revenue and cost structure. It neither predicts sales nor estimates the causal effect of a higher advertising budget.
At a positive fixed margin, break-even revenue = advertising spend × (1 + fee rate) ÷ margin. The result excludes overhead and assumes that the margin remains unchanged. A zero margin produces no defined break-even revenue.
Make the next review answerable.
| Action | Functional owner | Evidence for the review |
|---|---|---|
| Reconcile source periods, sales and recorded refunds | Finance / operations | A reconciled report with remaining differences explained |
| Inspect margin by product and market | Commercial lead | A cost bridge that accounts for the margin change |
| Run the approved creative tests within the existing budget | Paid media lead | Test log, spend limits and comparable reporting windows |
| Reassess any increase | Commercial decision-maker | Documented assumptions, contribution threshold and review date |
The media buying deliverable is the combination of the analysis, a practical campaign plan and a record of what changed. The decision should be revisited as evidence improves, rather than preserved because it appeared in a report.
Take the example apart.
Download the full decision memo, the two-period CSV and the metric definitions. These files contain only illustrative material.
Version 1.0 · Prepared 29 October 2026 · Reuse the method with your own reviewed definitions. Examples are provided for evaluation, without a guarantee of commercial results.