Klar
العربيةEN

Compound interest calculator

Calculate how your investment grows with compound interest and regular contributions, with a year-by-year breakdown of balance and returns.

Required fields are marked with an asterisk (*).

The amount you start investing or saving with.
The amount you add regularly at the chosen frequency; enter 0 if you do not plan to add more.
Contribution frequency
Choose how you make your contributions: monthly, quarterly or annually.
The expected annual return on your investment.
Compounding frequency
How often interest is added to the balance each year; more frequent compounding increases growth.
How many years the investment runs.
The currency used to display the results.

Compound interest is interest earned on your growing balance — on both the principal and the interest already earned — which makes your money grow faster over time. Enter your starting amount, regular contributions, interest rate and compounding frequency to see how your investment grows over the years.

Formula

The balance compounds every period: new balance = previous balance × (1 + period rate) + periodic contribution.

When is this useful?

Use this calculator to estimate the growth of retirement savings or long-term savings, compare different investment scenarios, and understand how compounding works on your money over time.

Worked example

Example using the calculator’s values: an initial 5,000 dollars with a 200 dollar monthly contribution at 7% per year, compounded monthly for 20 years.
The final balance is about 124,400 dollars.
Total contributions are 53,000 dollars, with about 71,400 dollars coming from interest.

Assumptions

  • The annual interest rate is fixed for the whole period.
  • Contributions are made at the end of each compounding period.
  • Interest is added to the balance and compounded at the chosen frequency.
  • Taxes, fees, inflation and market fluctuations are not included.
  • Results are estimates and do not guarantee real returns; past performance is not a guide to future results.

Common mistakes

  • Confusing the annual interest rate with how often interest compounds within the year.
  • Compounding only the initial amount and forgetting the periodic contributions.
  • Assuming a constant return, while real returns vary from year to year.
  • Ignoring the effect of inflation on the purchasing power of the final balance.
  • Overlooking fees and taxes that reduce the real return.

Frequently asked questions

What is the difference between compound and simple interest?

Compound interest is earned on the accumulated balance (principal plus previous interest), while simple interest is earned only on the principal, so compounding grows faster.

Are the returns guaranteed?

No. This is an estimating calculator that assumes a fixed rate; real returns vary with the market, and no projected amount guarantees future results.

What does compounding frequency mean?

It is how often interest is calculated and added to the balance each year. Monthly compounding grows faster than annual compounding at the same rate.

Can the contribution be zero?

Yes. Enter 0 as the periodic contribution to see how the initial amount alone grows.

Methodology and review

The calculator compounds interest on the balance and adds periodic contributions at the end of each period, showing the balance year by year. Results are theoretical and for planning. Tax and regulatory rules vary by country, so verify with the relevant authorities and do not treat results as guaranteed returns.

Results are estimates for informational purposes only and do not constitute investment advice or a guarantee of future returns.

Back to home