ROAS meaning: what return on ad spend tells you

What ROAS means

ROAS stands for return on ad spend, sometimes return on advertising spend. It sets the revenue an ad produced against what the ad cost. $1,000 in ad spend and $4,000 in revenue give you a ROAS of 4.

You will meet the same value in three notations:

• As a multiple: ROAS 4. Most reports and dashboards use it.
• As a ratio: 4:1. Common in agency decks and US marketing blogs.
• As a percentage: 400%. Google Ads expects this format in the target ROAS bid strategy.

In the Google Ads interface, the column is called Conv. value / cost. It shows the same multiple: conversion value divided by cost. For the step-by-step math with returns, margin and break-even, use the ROAS formula calculator.

ROAS vs. ROI, POAS, ACoS and MER

The five metrics sound alike and answer different questions. One example shows the difference. A campaign costs $5,000 and brings in $20,000 in revenue. After product, shipping, payment fees and returns, 40% of that remains as contribution margin, so $8,000. The whole store does $60,000 a month on $12,000 in total marketing spend.

ACoS (advertising cost of sales) is the inverse of ROAS. Amazon sellers use it daily. If you switch between Amazon and Google, this table converts one into the other:

Why the same ROAS can mean profit or loss

ROAS knows nothing about your costs. Three stores each spend $1,000 on ads. Revenue is counted after returns:

Store B loses money at the same ROAS that makes store A money. Store C sits well below ROAS 4 and still turns a profit. The line between the two is break-even ROAS, 1 ÷ contribution margin, which puts store B at 5.0. The breakeven ROAS calculator finds yours, including returns.

That is why every ROAS judgment needs your contribution margin. Without it you know how much revenue comes in. The margin tells you how much of it stays.

Platform ROAS and real ROAS

The ROAS in your ad account almost always sits above the one your store sees. Three effects add up:

• Returns and cancellations: The ad account counts a sale the moment the order comes in. Whatever comes back stays in the ROAS. According to the NRF 2025 Retail Returns Landscape, US shoppers were expected to return 19.3% of online sales in 2025.
• Double attribution: When someone clicks a Google ad and later an ad on a second channel, both platforms claim the same purchase.
• Sales that would have happened anyway: Existing customers who reach your store through a brand ad would mostly have bought without it.

Take a store with a platform ROAS of 5.0, 20% returns and 15% of its revenue also claimed by another channel:

1. Platform ROAS in Google Ads: 5.00
2. After 20% returns: 5.00 × 0.80 = 4.00
3. Without the 15% double-claimed revenue: 4.00 × 0.85 = 3.40

A ROAS of 5 shrinks to a real ROAS of 3.40 before you even ask which sales would have happened anyway. If your break-even sits at 3.5, a campaign that shines in the ad account loses money.

If your conversion value includes sales tax, or VAT for UK and EU sales, strip that out first as well. Compare the sum of all platform revenue with your store backend once a month. MER from the comparison table helps, because it needs no attribution.

Target ROAS in Google Ads at a glance

Target ROAS is a bid strategy. Google predicts the value of a possible conversion for each auction and adjusts bids to reach the ROAS you set on average. On Search and Shopping, you set it as an optional target inside the Maximize conversion value strategy.

A higher target makes Google more selective: less volume, higher ROAS. A lower target brings more revenue at a weaker ratio. Derive the value you enter from contribution margin and returns. The ROAS calculator page shows the target ROAS formula.

What is a good ROAS?

A good ROAS sits above your break-even ROAS plus the profit you want per order. No single number fits every store, as the three stores above show. Industry averages without margins send you in the wrong direction.

Set yourself two values: the break-even, below which a campaign loses money, and a target ROAS with a profit margin on top. New-customer campaigns can run closer to break-even when customers come back and buy again.

How to use ROAS well

• Steer by margin: Give high-margin products a lower target ROAS than products with thin contribution margin. Separate campaigns or product groups in the feed make that possible.
• Split brand and non-brand: Brand campaigns show high ROAS because many buyers would come anyway. Judge new-customer campaigns on their own.
• Measure in your store: Compare platform revenue with store backend revenue minus refunds every month.

As an agency for Google Ads working with ecommerce brands, we allocate budget by contribution margin. We measure results in your store backend, including for our $100k guarantee.