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# How to set target ROAS—and when to use POAS
- URL: https://conversion.club/playbook/target-roas-poas-contribution-margin/
- Published: 2026-10-29T09:14:21.000Z
- Updated: 2026-10-29T09:14:21.000Z
- Description: Calculate break-even ROAS from contribution before ads. Define POAS costs, align the tax basis, and distinguish attributed revenue from incremental sales.
- Author: Jeremie Werner
- Tags: Protect margin, #playbook, Acquisition, Analytics

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](https://conversion.club/playbook/how-do-you-calculate-the-contribution-margin-of-an-order/) 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](https://conversion.club/playbook/what-ltv-to-cac-ratio-should-you-aim-for-and-what-can-your-site-change/). Fixed costs and cash constraints still need coverage.

## The steps

1. **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.
2. **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.
3. **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.
4. **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.
5. **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](https://conversion.club/playbook/how-do-i-know-if-my-ads-drive-sales-i-wouldn-t-have-made-anyway/).

## 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.”

## Sources

- [Google Ads Help: Target ROAS bidding](https://support.google.com/google-ads/answer/6268637?hl=en&ref=conversion.club)
- [Polar Analytics: Profit on ad spend](https://www.polaranalytics.com/post/poas-profit-on-ad-spend?ref=conversion.club)
- [Kickbite: POAS definition](https://www.kickbite.io/en/blog/poas-definition?ref=conversion.club)
- [Google Ads Help: Conversions with cart data](https://support.google.com/google-ads/answer/9028254?hl=en&ref=conversion.club)
- [Jon Loomer: Meta Ads attribution in 2026](https://www.jonloomer.com/meta-ads-attribution-2026/?ref=conversion.club)
- [Google Ads Help: Data-driven attribution](https://support.google.com/google-ads/answer/6394265?hl=en&ref=conversion.club)