Common Mistakes When Calculating ROI

Return on Investment is one of the most commonly cited business metrics, yet it is also one of the most commonly miscalculated. Here are five mistakes to watch for.

1. Forgetting to Include All Costs

The most common ROI mistake is underestimating costs. If you spent $10,000 on a marketing campaign, that number should include ad spend, agency fees, tool subscriptions, and the time your team spent managing it. Leaving out any cost artificially inflates your ROI.

2. Using Revenue Instead of Profit

ROI should measure profit, not revenue. If you spent $10,000 and generated $50,000 in revenue but your cost of goods was $35,000, your actual profit is $15,000 and your ROI is 50%, not 400%.

3. Ignoring the Time Value of Money

A 50% ROI over one year is very different from 50% over five years. For longer-term investments, use NPV or CAGR instead of simple ROI to account for the time value of money.

4. Cherry-Picking the Time Period

Measuring ROI over a period that conveniently captures a spike (like Black Friday) without including the full campaign duration gives a misleading picture. Always measure ROI over the complete investment lifecycle.

5. Not Comparing to Alternatives

An ROI of 30% sounds good, but not if you could have earned 50% by putting the same money elsewhere. Always compare ROI against your next best alternative investment opportunity.

Use our free ROI Calculator to get accurate numbers, and pair it with the NPV Calculator for investments spanning multiple years.