# How to Calculate ROI (Return on Investment) the Right Way

> ROI is the simplest measure of whether an investment paid off. Here's the formula, a worked example, and the one thing people forget when comparing returns.

- URL: https://www.pyalm.com/blog/how-to-calculate-roi
- Author: Fadhil Abdulla
- Category: Pyalm Books
- Published: 2026-06-16
- Updated: 2026-06-16

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## What ROI measures

Return on investment (ROI) tells you how much profit an investment generated relative to its cost, as a percentage. It's the quickest way to compare options — a marketing campaign, a new machine, a hire. The free [ROI Calculator](https://www.pyalm.com/free-tools/roi-calculator) does the maths for you.

## The formula

ROI = (amount returned − amount invested) ÷ amount invested × 100.

Invest AED 10,000 and get back AED 13,000, and your ROI is 30%. The net return is AED 3,000.

## The thing people forget: time

A 30% ROI over one month is spectacular; over five years it's modest. Always note the time period, and when comparing investments of different lengths, think in annualised terms. ROI alone doesn't capture risk or timing — use it alongside, not instead of, judgement.

## Where ROI is useful

- Comparing marketing channels by return.
- Justifying equipment or software purchases.
- Evaluating whether a project beat its cost of capital.

To know your true returns you need clean numbers on costs and revenue — exactly what [Pyalm Books](https://www.pyalm.com/books) keeps organised. You can also pair ROI with the [Business Valuation Calculator](https://www.pyalm.com/free-tools/business-valuation-calculator).

[Use the free ROI Calculator](https://www.pyalm.com/free-tools/roi-calculator) | [Explore Pyalm Books](https://www.pyalm.com/books)