ACOS vs ROAS vs TACOS: which ad metrics should D2C brands track?
Understand ACOS, ROAS and TACOS for Amazon, Flipkart and quick-commerce ads: formulas, worked examples, what each metric tells you, and how to track them across platforms.
Marketplace advertising is now one of the largest costs for many D2C brands. Yet the metrics used to judge it are often misunderstood, or calculated differently by each platform and each team. Three metrics come up most often: ACOS, ROAS and TACOS. Here's what each one means, how to calculate it, and when to use it.
ROAS: return on ad spend
Spend ₹10,000 on ads that generate ₹50,000 in attributed sales, and your ROAS is 5.0 (often written 5x).
ROAS tells you how much revenue each rupee of advertising brought in, according to the platform's attribution. Higher is better. It's the most common metric across Meta, Google and many marketplace ad platforms.
ACOS: advertising cost of sale
Using the same example: ₹10,000 ÷ ₹50,000 = 20% ACOS.
ACOS is simply the inverse of ROAS, expressed as a percentage. Amazon popularised it, and it's useful because it compares directly with your margin. If your product's margin before advertising is 30% and your ACOS is 20%, those ad sales are still profitable. If ACOS is 40%, you're losing money on each ad-driven sale.
TACOS: total advertising cost of sale
If total sales for the product were ₹2,00,000 in the same period, TACOS = ₹10,000 ÷ ₹2,00,000 = 5%.
TACOS answers a different and arguably more important question: how much of our total revenue are we spending on ads? It accounts for the fact that advertising also lifts organic sales, by improving rank and visibility, and that some ad-attributed sales would have happened anyway.
Which metric should you use?
| Metric | Best for | Watch out for |
|---|---|---|
| ROAS | Comparing campaigns and platforms quickly | Attribution windows differ by platform |
| ACOS | Checking campaign profitability against margin | Ignores the organic sales that ads help create |
| TACOS | Judging whether ads are growing the whole business | Needs sales and ads data joined together |
In practice, you need all three. Use ROAS or ACOS to optimise individual campaigns and keywords, and TACOS to judge overall advertising health by product and channel.
Reading TACOS over time
- Ad spend up, TACOS flat or down: ads are growing total sales. A healthy sign.
- Ad spend up, TACOS rising steadily: you're buying sales you might have had anyway, or ads aren't lifting organic performance.
- TACOS falling while spend is stable: organic sales are growing. Rank, reviews or content improvements are paying off.
Why these metrics are hard to track across platforms
Each ad platform reports on its own terms. Attribution windows differ, some report ROAS and some ACOS, and product identifiers differ by marketplace. And TACOS can't be calculated inside an ad console at all, because it needs total sales data from the seller side.
To track these metrics properly you need to:
- Collect ad data from every platform (Amazon Ads, Flipkart Ads, quick-commerce ad platforms, Meta and Google).
- Collect total sales by SKU from each channel.
- Map every platform's product IDs to your own SKUs.
- Calculate ROAS, ACOS and TACOS the same way for every channel.
One more metric: inventory-aware spend
A common and expensive mistake is advertising products that are about to go out of stock. Clicks keep costing money, but conversion drops. Joining ad data with inventory lets you flag or pause spend on SKUs with low days of cover, and focus budget on products you can actually deliver.
Key takeaways
- ROAS = attributed sales ÷ spend. ACOS = spend ÷ attributed sales. They're inverses.
- TACOS = spend ÷ total sales, and shows whether ads grow the whole business.
- Use ACOS or ROAS for campaign optimisation, and TACOS for strategy.
- Join ads, sales and inventory data to calculate these consistently and avoid wasted spend.