Compound Interest Calculator
Calculate compound interest growth with regular contributions Free, browser-based, no sign-up required.
Reference-only finance estimates
Rates, fees, taxes, and provider-specific rules can change the real result. Use these tools for planning and comparison, then confirm terms with the relevant institution.
What is Compound Interest Calculator?
Compound interest is the interest calculated on both the initial principal and the accumulated interest from previous periods — often described as 'interest on interest.' This powerful concept is the foundation of long-term wealth building and investment growth. This free online compound interest calculator lets you project how your money will grow over time with different compounding frequencies (daily, monthly, quarterly, semi-annually, or annually) and optional regular monthly contributions. The interactive stacked area chart and year-by-year table help you visualize the power of compounding over your investment horizon.
How to Use
- Enter your initial investment amount (principal).
- Set the annual interest rate.
- Choose the investment period in years.
- Select the compounding frequency (how often interest is calculated and added to your balance).
- Optionally enter a monthly contribution amount for regular deposits.
- View the results including final amount, total interest earned, total invested, a year-by-year growth table, and an interactive stacked area chart showing how principal and interest grow over time.
How It Works
The calculator uses the compound interest formula: A = P(1 + r/n)^(nt) + PMT x ((1+r/n)^(nt) - 1) / (r/n), where P is the initial principal, r is the annual interest rate (as a decimal), n is the number of compounding periods per year, t is the number of years, and PMT is the regular contribution per period. The year-by-year breakdown simulates each compounding period to show exactly how your investment grows. All calculations run entirely in your browser — no data is sent to any server.
Common Use Cases
- Planning long-term savings goals by projecting investment growth over decades
- Comparing the effect of different compounding frequencies on final returns
- Understanding the power of regular monthly contributions alongside compound growth
- Evaluating retirement savings projections with consistent monthly deposits
- Comparing different interest rates to see their impact on long-term wealth
- Educational tool for understanding the 'miracle of compound interest' concept
Frequently Asked Questions
What compounding frequency gives the best returns?▼
More frequent compounding produces slightly higher returns. Daily compounding yields more than monthly, which yields more than annually. However, the difference is typically small for moderate interest rates. The key drivers of growth are the interest rate, time horizon, and regular contributions.
Is my data safe?▼
Yes. All calculations are performed entirely in your browser using JavaScript. No financial data is sent to any server or stored anywhere.
Does this account for inflation?▼
No. The calculator shows nominal returns only. To estimate real (inflation-adjusted) returns, subtract the expected annual inflation rate from the interest rate before calculating. Consult a financial advisor for comprehensive planning.
Can I use this for retirement planning?▼
This calculator provides useful projections for retirement savings growth. However, actual retirement planning should also consider taxes, inflation, withdrawal strategies, Social Security benefits, and market volatility. Consult a financial professional for comprehensive retirement planning.
What is the Rule of 72?▼
The Rule of 72 is a quick way to estimate how long it takes for an investment to double. Divide 72 by the annual interest rate — for example, at 6% interest, your money doubles in approximately 12 years (72/6 = 12).
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