Any marketer can provide information on how much they spent in the last quarter. But a lot of them are unable to provide information on what their expenditure actually yielded. This is where waste happens in budgets. This is also the reason good channels are no longer funded while bad ones get more money.

Measuring return on investment correctly consists not in finding the exact number but in creating a system of measurement that relates the money spent to earned money while being truthful about all the scruffy bits of money spent and still providing the information necessary to make good decisions.

Use the Basic Formula and Its Limits

The simple formula for ROI is:

ROI = (Revenue from marketing − Marketing cost) / Marketing cost × 100

For example, if you invested $10,000 and obtained $40,000 from that spend, your ROI will be 300%. 

This formula is a good starting place but can lead to errors in three situations.

• It views revenue derived from marketing as something easily identified, although as far as attribution is concerned, it is not.
• The standard formula may be based on gross revenue instead of profit.
• It ignores time.

In order to get the right measurements, those problems must be addressed.

Step 1: Define What a “Return” Actually Means for You

This means that you need to establish which return will be measured. Defining ambiguous objectives will lead to equally vague results.

You should align your ROI calculation with a precise conversion that has potential for monetization:

• E-commerce: purchase made with the order value
• Lead generation/B2B: qualified leads, opportunities, or closed deals (not merely form submissions)
• Subscription/SaaS: trial periods that convert to paid subscriptions with follow-up revenues.

If your sales cycle is extensive, or if it happens offline, your analytics should not stop at tracking clicks only. You have to monitor your leads till the point of revenue, meaning that you have to link your marketing tools with a CRM.

Step 2: Use Profit, Not Just Revenue

The ROI based on revenue exaggerates the profitability of the business because it does not account for the cost of delivering its products or services. If possible, use gross profit or contribution margin instead. 

The return on ad spend (ROAS), or revenue divided by advertising spend, is good for comparing channels, but don’t forget that ROAS is a revenue measure, not a profit measure. A 4:1 ROAS could still be a losing proposition if margins are slim and fulfillment costs are high. 

A more honest version of the formula:

Profit ROI = (Revenue × Gross margin − Total marketing cost) / Total marketing cost × 100

Step 3: Count All the Costs

When assessing the cost-benefit of a marketing effort, marketers are often guilty of understating their costs, resulting in an overstated ROI. A full accounting of marketing costs should include:

• Advertising and media buys
• Software and tools (analytics, automations, CRM, design software)
• Agency or consultant fees
• Wages and effort of in-house employees
• Creation costs (copy, videography, design)
• Overhead assigned to marketing function

Although exact accounting is not required, leaving out labor and tools creates the impression that a marketing channel is profitable, when it might not be the case.

Step 4: Set Up Reliable Tracking

If you have not tracked it, you cannot go back to get that data. A good tracking foundation involves using:

• A platform that offers analytics and conversion tracking, for example, GA4, that records conversion data reflecting the definitions in Step 1 with the monetary worth of the transaction.
• Every UTM parameter created by the marketing effort applied consistently to ensure that both traffic and revenue come from the right source, medium, and effort.
• Conversion tracking, such as ad tracking through platform pixels or server-side conversions, to get the information back into the system.
• A system to ensure that every customer who interacts with your site has their lead information linked back to revenues made months after.
• The use of server-side tracking or two protocols to follow privacy rules in the way of tracking.

Keep in mind to have a UTM naming system in place.

Step 5: Choose an Attribution Model and Know Its Bias

Attribution is responsible for deciding which touchpoint should be accountable for the conversion. The method you choose can affect your ROI calculations, so make a smart selection.

• Last click attribution gives full credit to the last touchpoint. It is a straightforward approach but gives too much importance to bottom of the funnel channels (such as branded search) while undervaluing awareness stages of the funnel.
• First click attribution assigns credit to the very first touchpoint. This method places too much emphasis on discovery stages of the funnel.
• Linear approach distributes credit equally among all touchpoints. Although fair, this model suffers from the lack of granularity.
• The time decay model gives more credit to those touchpoints that are close to the conversion event.
• The position based model, or U-shaped attribution model, assigns significant credit to the first and the last touchpoint and less to those in the middle.
• Data-driven attribution gives you the most precise results, as this approach considers your actual conversion numbers.

There is no perfect model, so the right thing to do is to choose the one and stick to it long enough to be able to compare the results across time and try to analyze the data through another lens occasionally.

Step 6: Account for Time and Customer Lifetime Value

While two campaigns can have the same short-term ROI, their actual value can vary significantly.

1. Lifetime value: If a customer acquired this month continues to make purchases over the next two years, measuring the acquisition campaign’s ROI considering only the first purchase undervalues it severely. In subscription and repeat purchase businesses, you should compare your customer acquisition expenses (CAC) against lifetime value (LTV). A healthy LTV/CAC ratio is generally considered to be about 3:1, though the right value depends on the type of business and the margin.

2. Payback period: Measure how long it takes to recover your acquisition cost. A marketing channel that shows a lower ROI but gives back money faster is more important for cash flow compared to a more profitable one that acts slowly.

Step 7: Isolate Causation, Not Just Correlation

Attribution gives you an idea about all the channels used prior to a conversion but does not indicate which channel caused it. There are scenarios where a customer would have bought the product anyway. To truly understand the incremental impact:

• Incrementality testing – conduct controlled tests such as geo-holdouts and audience-holdouts by stopping or changing spending and measuring the outcome.
• A/B testing – testing different versions of the marketing campaign to see what truly matters.
• Media mix modeling (MMM) – a statistical, privacy-respecting way of estimating the contributions of each channel using aggregated data over time when tracking attribution fails.

Incrementality has an honest question underneath the ROI: what would have happened if this money had not been spent? The closer one gets to the answer, the more accurate the ROI.

Conclusion

Correct digital marketing ROI results from a process, not from a single spreadsheet cell. Identify actual results, track them correctly, assess them against profit and lifetime value, be mindful of your attribution, and measure incremental effect. If done, your return on investment number will go from being the feel-good number to a precise road map on where to put your next dollar.