Compound Growth Calculator - Free Investment Calculator 2026

What is Compound Growth?

Compound growth occurs when your investment returns generate their own returns. Unlike simple interest, where you only earn on your original principal, compound growth means your earnings are reinvested to generate additional earnings over time. This creates an exponential growth curve that becomes increasingly powerful the longer you stay invested.

For example, if you invest $10,000 with an 8% annual return, after one year you'd have $10,800. In year two, you earn 8% on $10,800, not just the original $10,000. This seemingly small difference compounds dramatically over decades, which is why starting early is one of the most important factors in building wealth.

How to Use This Calculator

Our compound growth calculator helps you visualise how your investments could grow over time. Simply enter your starting amount, how much you plan to add each month, your expected annual return rate, and how long you plan to invest. The calculator will show you:

• Total Invested: The sum of your initial investment plus all monthly contributions
• Interest Earned: How much your investments have grown through compound returns
• Final Balance: Your projected portfolio value at the end of the investment period
• Growth Multiplier: How many times your money has grown compared to what you put in

The interactive chart displays your total balance (green line) versus your contributions (gold line), making it easy to see how much of your wealth comes from compound growth versus your own deposits.

What Annual Return Should You Expect?

Historical stock market returns have averaged around 7-10% annually over the long term, though past performance does not guarantee future results. Here are some general benchmarks to consider:

• Conservative (4-6%): Bond-heavy portfolios or high-yield savings accounts
• Moderate (6-8%): Balanced portfolios with a mix of stocks and bonds
• Aggressive (8-10%): Stock-heavy portfolios, particularly broad market index funds

Keep in mind that actual returns will vary year to year. Some years the market may return 20% or more, while others could see negative returns. The key is staying invested for the long term to capture the average growth over time. If you're unsure which investment platform suits your strategy, our broker comparison can help you decide.

The Power of Starting Early

Time is the most important factor in compound growth. Consider this example: if you invest $500 per month starting at age 25 with an 8% annual return, by age 65 you'd have approximately $1.74 million. Start at age 35, and you'd have around $745,000. That ten-year head start nearly doubles your final balance, even though you only invested an extra $60,000.

This is why financial advisors consistently emphasise starting to invest as early as possible, even with small amounts. The compound growth effect does the heavy lifting over time.

Tips for Maximising Your Investment Growth

• Start now: The best time to start investing was yesterday. The second best time is today.
• Stay consistent: Regular monthly contributions, even small ones, add up significantly over time.
• Increase contributions annually: Use the "Annual Deposit Increase" feature to account for salary raises.
• Keep fees low: High fees can significantly erode your returns over time. Use our ETF Fee Calculator to see how much you could save.
• Stay invested: Avoid the temptation to time the market. Consistent investing through ups and downs typically outperforms trying to predict market movements.
• Reinvest dividends: If your investments pay dividends, reinvesting them adds to your compound growth.

Related Financial Calculators

Planning your financial future involves more than just compound growth. Explore our other free calculators to get a complete picture of your investment strategy:

• FIRE Calculator - Calculate how much you need to retire early and achieve financial independence
• ETF Fee Calculator - See how fund fees impact your long-term returns and find cost-effective investments
• Dividend Investing Calculator - Project your passive income from dividend-paying stocks

Ready to Start Investing?

Now that you've seen how powerful compound growth can be, the next step is choosing the right platform to start your investment journey. Different brokers offer varying fee structures, investment options, and features. Browse our broker reviews to find the best fit for your needs, or check out our guides on popular platforms like Trading 212, eToro, and Interactive Brokers.