Return on Investment (ROI) Formula: A South African Guide

What is ROI?

Return on Investment (ROI) is a financial metric used to measure the profitability or efficiency of an investment. It essentially tells you how much return you’re getting on the money you put in. Understanding ROI is crucial for South African investors because it helps them compare different investment options and make informed decisions about their finances.

The Basic ROI Formula

The most common formula for calculating ROI is:

ROI = (Gain from Investment – Initial Investment) / Initial Investment x 100%

Here’s a breakdown of the formula:

  • Gain from Investment: This is the total profit or benefit you receive from your investment. It could be income generated (like rental income from property), capital appreciation (increase in the value of an asset), or a combination of both.
  • Initial Investment: This is the total amount of money you initially put into the investment. It includes the purchase price of the asset and any additional costs associated with the investment (e.g., brokerage fees for stocks).


Let’s say you invest R100,000 in a stock that increases in value to R120,000 after one year. You don’t receive any dividends during that year.

ROI = (R120,000 – R100,000) / R100,000 x 100% = 20%

This means your investment generated a 20% return on your initial investment over one year.

Important Considerations for South African Investors

  • Time Horizon: ROI is typically calculated over a specific period. Consider your investment timeframe when evaluating ROI. A short-term investment might have a higher ROI than a long-term one, but that doesn’t necessarily mean it’s a better investment for your goals.
  • Cash Flow: The basic ROI formula doesn’t account for ongoing costs associated with the investment. For example, if you own a rental property, you’ll have expenses like maintenance and property taxes. These costs should be factored in for a more accurate picture of your return.
  • Taxes: Capital gains taxes and other investment-related taxes can affect your overall return. Be sure to factor in potential tax implications when calculating ROI.
  • Risk vs. Return: Generally, investments with higher potential returns also carry higher risks. Consider your risk tolerance when choosing investments and understand the risk profile before calculating ROI.
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South African Resources for ROI

Several South African financial institutions offer ROI calculators on their websites. These tools can help you estimate the potential return on various investments based on your specific input. Here are a few examples:


The ROI formula is a valuable tool for South African investors to assess the profitability of their investments. Remember, ROI is just one piece of the puzzle. Consider your investment goals, risk tolerance, and tax implications before making investment decisions.