Try a published example
Loading replaces the current inputs only. Existing saved plans remain intact.
Compound Interest Calculator
See how a starting amount plus regular monthly deposits grows with compounding — including total interest earned.
Your inputs
Result
Yearly breakdown
| Year | Deposited | Interest | Balance |
|---|
How compound interest works
Each period you earn interest on your balance, and that interest is added back so it earns interest too. Adding regular deposits accelerates the effect — the earlier and more consistently you contribute, the larger the final balance.
FAQ
What is compound interest?
Interest earned on both your principal and previously-earned interest, so growth speeds up over time.
Does compounding frequency matter?
Yes, a little — more frequent compounding gives a slightly higher result for the same annual rate.
Estimate only; actual returns vary and are not guaranteed.
Set deposit timing and compounding
Enter the starting amount, regular monthly deposit, annual nominal rate, term and compounding frequency. The model adds each monthly deposit at month-end after growth for that month. Deposits at the start of each month would earn more, so do not compare the result with a different deposit convention without adjusting assumptions.
Separate your deposits from growth
With RM10,000 initially and RM500 added each month for one year, total money deposited is RM16,000. At a 0% rate, the final amount is exactly RM16,000 and growth is zero. At a positive assumed rate, use the interest figure to distinguish modelled growth from money you contributed yourself.
Equivalent monthly rate
For nominal annual rate r compounded n times per year, the simulated monthly rate is (1+r/n)^(n/12) − 1. Each month uses B(next) = B × (1+monthly rate) + monthly deposit. Returns are constant and reinvested; taxes, charges, inflation and investment losses are not modelled. A forecast is not a guaranteed return.
Calculation methods and limitationsExample calculations checked against this page’s code on 7 October 2026.
Questions worth working through
Use the result with confidence
Distinguish growth from new money
The final balance contains starting capital, regular deposits and modelled growth. With 10,000 initially and 500 per month for one year at 0%, the final balance is 16,000 and the gain from returns is zero. A growing balance alone does not tell you the investment return.
Why compounding frequency matters
The tool converts the selected annual compounding convention to an equivalent monthly growth factor and adds deposits at month-end. For the same quoted nominal rate, annual and monthly compounding can therefore differ. When comparing another calculator, match deposit timing and rate conventions before comparing totals.
Use a range of assumptions
Change the return while keeping your deposits constant to see how sensitive the result is. A smooth curve is a fixed-rate illustration, not the path of a stock fund. This tool does not subtract fees, taxes or inflation; Financial Planning offers separate fee and inflation assumptions.
Understand the numbers with worked examples
A zero-return check
Start with RM10,000, add RM500 at each month end for one year, with zero interest: RM16,000 in total, including RM6,000 of new deposits. Change one input at a time after loading.
Open this example