Short answer
Calculate break-even ROAS from contribution before ads. Define POAS costs, align the tax basis, and distinguish attributed revenue from incremental sales.
The answer in detail
Break-even ROAS is 1 ÷ contribution-margin rate before advertising. At 45%, each dollar of ads needs $2.22 of tax-exclusive sales to cover the modeled variable costs and advertising. POAS divides pre-ad contribution by ad spend, giving a break-even threshold of 1 under that definition. It is especially useful when product margins differ.
The benchmark
Google Ads defines target ROAS as the average conversion value desired per unit spent, entered as a percentage. Five dollars in value per dollar spent is 500%. That value does not automatically include your margin economics.
The fictional apparel example retains 45% of tax-exclusive sales after product cost of 35%, logistics of 12%, payment fees of 2%, and returns of 6%.
| Fictional measure | Calculation | Result |
|---|---|---|
| Break-even ROAS, tax-exclusive revenue | 1 ÷ 0.45 | 2.22 |
| Same threshold on revenue including illustrative 20% VAT | 2.22 × 1.2 | 2.67 |
| ROAS retaining ten percentage points after ads | 1 ÷ (0.45 − 0.10) | 2.86, or 286% |
| Campaign with $30,000 revenue and $10,000 spend | 30,000 ÷ 10,000 | 3.0 |
| Its contribution-based POAS | 30,000 × 0.45 ÷ 10,000 | 1.35 |
The cited Polar Analytics and Kickbite definitions both use POAS break-even of 1 but deduct different costs. Polar's example includes products, shipping, and payments; Kickbite also includes packaging and expected returns. Ask what “profit” means before comparing dashboards. Here it means contribution before ads, not bottom-line profit after fixed costs.
The rule
Derive the target from contribution margin rather than gross margin or an industry average. A fictional 55% product gross margin implies 1.82 break-even ROAS; after logistics, payments, and returns reduce contribution to 45%, it becomes 2.22.
POAS helps when margins vary: ROAS 3 fails to cover ad spend at 25% contribution but clears it at 60%. With uniform margins, ROAS can lead to the same decision and is simpler to configure.
A below-first-order-break-even acquisition strategy may be justified by evidenced repeat contribution and affordable payback. Do not assume future purchases will rescue it; use LTV/CAC analysis. Fixed costs and cash constraints still need coverage.
The steps
- Calculate the rate. Over twelve months, subtract product cost, logistics, payment fees, and returns from tax-exclusive sales, then divide by the same sales base. Keep advertising outside this pre-ad rate.
- Calculate break-even. Divide 1 by the rate. If the conversion tag sends tax-inclusive values, translate the threshold onto that basis using the actual applicable tax treatment. The source's 1.2 multiplier assumes uniform 20% VAT; it does not cover every market, mixed tax basket, or shipping-inclusive value.
- Set retained contribution. Decide the percentage of revenue that must remain after ads. Use
1 ÷ (contribution rate − retained rate). Enter 2.86 as 286% in Google Ads. - Reconcile attribution. Review brand campaigns separately each month. Compare the sum of platform-claimed revenue with Shopify totals; overlapping claims can coexist with email and organic sales.
- Measure before changing bids. Google cart-data conversions combined with Merchant Center product costs can report gross profit, excluding some logistics and returns. To bid on contribution, send a reliable order-level contribution value. The target changes units:
contribution rate ÷ (contribution rate − retained rate). At 45% and ten points retained, that is 1.29, entered as 129%.
The pitfall
Attributed ROAS is not incremental ROAS. Check the actual click-through and view-through attribution windows configured in the ad set; platform settings are not a measure of incrementality. Google data-driven attribution distributes credit across eligible Google interactions, not an independent estimate of sales that would otherwise never happen.
In the fictional campaign, if only 70% of claimed $30,000 sales are incremental, incremental ROAS is 2.1 and POAS 0.945. Contribution is $550 below ad spend while the platform displays ROAS 3.
In a Club outdoor-equipment case, brand campaigns supported the overall Google result. Nonbrand ROAS was 2.05 excluding tax in Google, versus roughly 1.2 in a separate attribution tool using one-day-click measurement. A shorter window explains only part of the difference and is not itself causal proof. Use an incrementality test.
What to tell your team
These numbers are fictional:
“Our pre-ad contribution rate is 45%, so break-even ROAS is 2.22 on tax-exclusive sales, or 2.67 with illustrative 20% VAT. We target 286% to retain ten revenue points and reconcile nonbrand performance against Shopify and incrementality evidence.”
