Marketing ROI: How to Measure Whether Your Campaigns Actually Work

You spent $5,000 on Google Ads last month. Sales increased by $18,000. Was that a good ROI?

Maybe. But probably not the 260% ROI it looks like at first glance.

Marketing ROI is one of the most misquoted metrics in business. Here's how to calculate it honestly.

The Correct Marketing ROI Formula

Most people calculate marketing ROI like this:

ROI = (Revenue Generated - Marketing Cost) ÷ Marketing Cost

This is wrong. Revenue isn't profit. You need to account for what it costs to deliver what you sold.

The correct formula:

Marketing ROI = (Gross Profit from Campaign - Marketing Cost) ÷ Marketing Cost × 100

Where Gross Profit = Revenue - Cost of Goods Sold (COGS)

Back to the Example

$5,000 in Google Ads → $18,000 in revenue.

But what did those sales cost to deliver?

• Cost of goods/services: $10,000
• Gross profit: $18,000 - $10,000 = $8,000

Marketing ROI = ($8,000 - $5,000) ÷ $5,000 × 100 = 60%

Still good — but very different from the 260% figure using revenue alone.

And it gets more complex: did that $18,000 in sales come entirely from the campaign? Or would some of those customers have found you anyway? Attribution is the hardest problem in marketing measurement.

Attribution: The Real Challenge

Attribution means determining which marketing activity actually caused a sale.

A customer might:

1. See your Instagram ad
2. Google your brand name
3. Read a blog post on your site
4. Receive an email from you
5. Click a Google Ad
6. Buy

Which touchpoint gets credit for the sale? The last one (Google Ad)? All of them proportionally? The first one that introduced them to your brand?

Different attribution models give different answers — and different marketing ROI calculations.

Common attribution models:

• Last click: All credit to the final touchpoint before purchase
• First click: All credit to the first touchpoint
• Linear: Equal credit to all touchpoints
• Data-driven: Algorithm assigns credit based on which touchpoints actually correlate with conversion

Customer Lifetime Value: The Number That Changes Everything

Short-term marketing ROI often looks bad for businesses with high customer lifetime value (LTV).

Example: A SaaS company spends $200 in ads to acquire a customer who pays $50/month and stays for 24 months. LTV = $1,200.

First-month ROI: ($50 - $200) ÷ $200 = -75%. Terrible.

Lifetime ROI: ($1,200 - $200) ÷ $200 = 500%. Excellent.

Measuring marketing ROI on a single transaction basis for subscription or repeat-purchase businesses almost always undervalues effective campaigns.

Benchmarks: What Is Good Marketing ROI?

Marketing ROI varies enormously by channel and industry:

The 5:1 rule is common guidance: for every $1 spent on marketing, aim for $5 in gross profit. That's a 400% ROI.

Calculate the ROI of any business investment with our ROI Calculator.