See how your investments grow over time using the Compound Interest Calculator with compounding interest calculations.
| Year | Opening Balance | Interest Earned | Contributions | Closing Balance |
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Type in your starting principal, the annual interest rate, and pick your compounding frequency — daily, monthly, quarterly, or annually.
Choose the investment duration in years or months. Optionally add regular monthly, weekly, or annual contributions to model ongoing savings.
Results update as you type: final balance, compound interest earned, APY, growth multiple, and a full year-by-year schedule — no button needed.
Copy to clipboard, download a CSV with the full growth schedule, or print a clean PDF report for records, planning, or presentations.
Results update as you type — no Calculate button needed. Change any value and instantly see how it affects your final balance and total interest.
Choose from daily, weekly, monthly, quarterly, semi-annual, annual, or continuous compounding to match any real-world investment or loan product.
Model ongoing savings plans by adding monthly, weekly, quarterly, or annual contributions and see how they dramatically accelerate wealth growth.
A full annual schedule shows opening balance, interest earned each year, contributions, and closing balance — scroll through the entire growth timeline.
All calculations run entirely in your browser. No data is ever sent to a server, stored, or tracked — your financial figures stay completely private.
The full applied formula with your substituted values is shown in the results panel — perfect for students, educators, and financial professionals.
Fully responsive design works perfectly on desktop, tablet, and mobile. Calculate anywhere — in class, at the bank, or planning on the go.
Download results as a CSV for spreadsheets, print a clean PDF report, or copy everything to clipboard to paste wherever you need it.
Compound interest is calculated on both the original principal and the accumulated interest from previous periods. Unlike simple interest, your interest earns interest — creating an exponential "snowball" effect over time.
The formula is A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate (decimal), n is compounding periods per year, and t is time in years. The difference CI = A − P is your compound interest earned.
Interest earns interest. In compound growth, each period's interest is added to the principal, so the base on which future interest is calculated keeps growing — slowly at first, then dramatically.
The more often interest compounds, the more you earn. Daily compounding yields slightly more than monthly, which beats quarterly. The difference widens significantly over long time horizons.
The most powerful lever in compound interest is time. Starting 10 years earlier can double or triple your final balance — more so than increasing the rate or principal by the same percentage.
APR (Annual Percentage Rate) is the stated rate. APY (Annual Percentage Yield) accounts for compounding and is always higher than APR unless compounding is annual. Always compare APYs for savings.
Adding even small regular contributions (e.g., $100/month) compounds dramatically over time. The combination of compound growth and consistent deposits is the foundation of most retirement plans.
Divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 7%, your investment doubles in ≈10.3 years. At 10%, it doubles in ≈7.2 years.
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