Compound Interest Calculator: what this tool is for
Compound interest is one of the most formidable financial mechanisms for accumulating long-term wealth. Often celebrated as the 'eighth wonder of the world', it operates on an exponential principle: interest generated in each period is added to the principal balance, generating further interest in subsequent periods.
Unlike simple interest where gains are earned strictly on the original principal, compounding creates an accelerating 'snowball effect'. The longer your investment horizon and the more consistent your recurring contributions, the more passive compounding returns surpass your actual out-of-pocket deposits.
This free online Compound Interest and Savings Calculator accurately models the future trajectory of your financial portfolio: index funds (S&P 500, MSCI World ETFs), high-yield savings accounts, retirement plans (401k, IRA, ISA), or real estate deposits.
With customizable recurring deposits (monthly, quarterly, or annually), multiple compounding frequencies, visual asset breakdowns, and full yearly amortization tables, explore your final balance, net gains, and capital multiplier instantly with 100% client-side precision.
No file stored
Nothing is saved on our servers, during or after processing.
Local processing
The computation runs in your browser whenever the technology allows it.
Instant result
No waiting and no export queue: the result appears live.
Free, no account
No sign-up, no daily limit and no intrusive ads.
What this tool gives you
Recurring deposit simulations
Combine an upfront initial lump sum with monthly, quarterly, or annual recurring deposits to mirror your real-world saving capacity.
Flexible compounding frequencies
Choose between annual, semi-annual, quarterly, monthly, or daily compounding to accurately match your financial institution's terms.
Comprehensive year-by-year schedule
Inspect detailed year-end forecasts: starting balances, periodic deposits added, annual interest earned, and progressive totals.
Visual asset breakdown & 100% private
Explore dynamic proportion bars highlighting deposits vs compound interest. All computations execute locally on your device.
Real-world examples
Examine how time horizons and annual rates of return exponentially multiply a $10,000 lump sum over decades:
How to use Compound Interest Calculator
Enter your starting principal
Input the initial lump sum amount you invest upon opening the account (e.g., $5,000). If starting from zero, enter 0.
Set your recurring contribution
Specify the regular deposit amount (e.g., $200 per month or $2,400 per year) and contribution frequency.
Configure expected rate and timeline
Adjust the estimated annual interest rate slider (e.g., 7%) and target duration in years (e.g., 20 years).
Review projections and amortization
Inspect your final wealth total, the percentage earned purely through compound interest, and browse the full yearly growth schedule.
Tips and mistakes to avoid
Start as early as possible: time is your greatest compounding asset
Due to the exponential curve of compounding, investing $100 per month starting at age 20 produces substantially greater wealth by retirement than investing $300 per month starting at age 40.
Reinvest dividends automatically
Ensure your investment accounts or index funds are set to automatic dividend reinvestment (DRIP or Accumulating funds) to maximize continuous compounding efficiency.
Avoid : Underestimating the erosive effect of high expense ratios
A seemingly small 2% annual management fee can erode 30% to 40% of your total ending portfolio balance over 25 years. Opt for low-cost broad-market index funds (under 0.20% fee).
Avoid : Pausing periodic deposits during market downturns
Market corrections offer prime buying opportunities. Dollar-cost averaging (DCA) through recurring monthly deposits maximizes long-term compound performance.
Frequently asked questions
Answers to the questions people ask about Compound Interest Calculator.
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Updated on August 2026. See all tools