Why a 4x Return Can Still Lose Money (ROAS vs. ROI)

Why this matters

ROAS and ROI are both ratios that appear in every paid acquisition report, and conflating them is one of the most common analytical errors on growth teams. ROAS (Return on Ad Spend) measures revenue relative to ad spend only — it tells you nothing about profit. ROI (Return on Investment) measures profit relative to total investment including COGS, fulfilment, and overhead. A campaign can have a 4× ROAS and negative ROI if the product margin is thin enough.

Demo

ROAS = Revenue ÷ Ad Spend. ROI = (Revenue − Total Costs) ÷ Total Costs. The two ratios answer different questions and should never be used interchangeably.

Try it yourself

1. Increase cogs to 28000 and observe ROAS stays at 4x while ROI turns negative — confirm the exact breakeven COGS.
2. Add a 20% return rate (returns = revenue * 0.20) and recompute both metrics using net revenue — note which metric is more affected.
3. Find a real DTC brand's reported ROAS in a case study and estimate what their ROI might be given typical e-commerce gross margins (40–60%).
4. Set overhead_share to zero and recompute ROI — label this 'contribution-margin ROI' and explain when that framing is appropriate vs. misleading.

References

• https://support.google.com/google-ads/answer/6335023
• https://www.shopify.com/blog/roas