What is ROI in digital advertising and how to calculate it for ecommerce

ROI is the metric that separates campaigns that make money from those that only generate movement. Here you will understand exactly what it measures, how to calculate it and why ROAS is not enough.

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What ROI means

ROI stands for Return on Investment. It measures how much profit you generate for every dollar you invest.

In the context of digital advertising for ecommerce, ROI answers a specific question: after paying for ads and the cost of the product, is there any money left?

It differs from ROAS (which only compares revenue to ad spend) and from gross revenue (which deducts nothing). ROI is the most honest metric for evaluating whether a campaign makes real economic sense.

ROI formula for advertising

ROI = (Gross profit − Ad spend) ÷ Ad spend × 100

Where:

Gross profit: Revenue × gross margin (%). What is left after deducting the cost of goods.
Ad spend: The money spent on advertising in that period.
Gross margin: The percentage left from each sale after paying for the product (excludes fixed costs).

A positive ROI means you earned more than you invested. An ROI of 0% means you recovered exactly what you invested. A negative ROI means losses.

Practical ROI example for ecommerce

A store launches a campaign with these figures:

Ad spend: $600

Revenue generated: $2,400

Gross margin: 40%

Gross profit: $2,400 × 0.40 = $960

Applying the formula: ($960 − $600) ÷ $600 × 100 = ROI of 60%

For every $100 invested in advertising, this campaign generates $60 in net profit. The margin is sufficient to absorb the ad spend and leave profitability.

Now imagine the margin were 25% instead of 40%:

Gross profit: $2,400 × 0.25 = $600 → ROI = ($600 − $600) ÷ $600 × 100 = 0%

With a 25% margin, the same revenue and the same spend give an ROI of 0%. The campaign does not lose money, but it generates no profit. And that is before accounting for returns or logistics costs.

ROI vs ROAS: why they are different metrics

This is one of the most common points of confusion in ecommerce. ROAS and ROI measure different things and can contradict each other.

ROAS

Revenue ÷ Ad spend

Measures how much revenue each ad dollar generates. Does not deduct cost of goods.

ROI

(Gross profit − Ad spend) ÷ Ad spend

Measures real profit. Deducts cost of goods. The definitive profitability metric.

With a 25% gross margin, you need a ROAS of 4x just to achieve a 0% ROI. A 3x ROAS with that margin means negative ROI even if Meta or TikTok show the campaign is performing well.

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Frequently asked questions about ROI