Compound Interest Calculator
How much will my investments grow over time?
Visualize the power of compounding. Calculate how your initial principal and monthly contributions grow over time with compound interest.
Key Features
- Interactive parameters to customize your calculations.
- Dynamic, professional-grade charts for visual analysis.
- Real-time calculations and optimization suggestions.
- Completely free and secure to use — your inputs remain in your browser.
Understanding Compound Interest
Compound interest is the process of earning returns on previous returns, allowing wealth to accelerate over long periods.
What is compound interest?
It is the process where your returns generate their own returns. Over time, these gains build on top of previous gains, causing your portfolio curve to grow exponentially rather than linearly.
Why time matters
Because compounding accelerates exponentially over time, starting early has a much larger impact than saving a larger amount later. Time does the heavy lifting, not just your monthly deposits.
Contributions vs Growth
In the initial years, your deposits dominate your balance. But as the portfolio grows, compounding returns start to dwarf your regular contributions, driving the bulk of your annual wealth gains.
Inflation & Purchasing Power
Inflation reduces purchasing power. A nominal future sum will buy less than that same number does today. True future wealth projections should always be viewed in inflation-adjusted real dollars.
Is a 7% return realistic?
Historically, the U.S. stock market has delivered an average annual return of roughly 7% to 10% before inflation. Modeling with a conservative 7% nominal return rate (or around 5% real return after inflation) is widely accepted as a prudent starting point for long-term growth planning.
Why consistency beats timing
Attempting to time market highs and lows is notoriously difficult. Maintaining a consistent monthly contribution strategy—commonly known as dollar-cost averaging—ensures you buy more shares when prices are low and fewer when prices are high, smoothing out volatility.
Educational Disclaimer: Calculations are estimates using standard compound interest formulas and investment assumptions. They are intended for educational purposes only and do not represent guaranteed future investment performance. Inflation, tax considerations, and market volatility will impact real-world portfolio outcomes.
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