Compound Interest Calculator
Savings and investment growth with monthly deposits, any compounding, APY/AER and inflation-adjusted value.
By Syed Mubashir Ali · Last updated
Estimates only — not financial advice. Figures are calculated in your browser from the rates shown and may differ from your bank, lender or tax authority. Check important numbers before acting on them.
How to Use Compound Interest Calculator
- 1Enter your starting amount and how much you'll add each month or each year.
- 2Enter the interest rate (or expected investment return), the number of years and how often interest compounds.
- 3Optionally raise your contributions every year, choose whether deposits are made at the start or end of each period, and set an inflation rate.
- 4Read the final balance, what you contributed, the interest earned, the APY/AER and the value in today's money.
- 5Check the growth chart and the year-by-year table, then copy or share the result.
Frequently Asked Questions
How much will $10,000 grow to with $200 a month?
At 5% compounded monthly for 20 years, $10,000 plus $200 a month ($58,000 contributed in total) grows to about $109,333, of which about $51,333 is interest. In today's money, at 2.5% inflation, that's worth about $66,700.
What's the difference between APR, APY and AER?
The APR or nominal rate is the yearly rate before compounding. APY (US) and AER (UK) include compounding, so they show what you really earn in a year. A 4.5% rate compounded monthly is an APY/AER of 4.594%. Compare savings accounts by APY or AER.
How much will I have if I invest $500 a month for 30 years?
At an average 7% a year compounded monthly, $500 a month for 30 years ($180,000 contributed) grows to about $610,000. That's the effect of compounding over decades, and why starting early matters more than the amount.
Does compounding frequency matter?
A little: more frequent compounding earns slightly more. $10,000 at 5% for 10 years becomes $16,288.95 compounded yearly and $16,470.09 compounded monthly. The rate and the time invested matter far more.
Can I use it for a 401(k), IRA, ISA or pension?
Yes. Enter your current balance, your monthly contribution (including any employer match) and an expected return. Tax-advantaged accounts let the growth compound without yearly tax; the calculator doesn't apply tax or fees, so treat the result as a before-fees estimate.
About Compound Interest Calculator
This compound interest calculator shows how savings and investments grow when interest earns interest. It handles the way people actually save: a starting balance plus regular monthly or yearly deposits, contributions that rise each year, and compounding daily, monthly, quarterly or yearly.
Alongside the final balance it shows how much came from your own deposits and how much from interest, the APY or AER the compounding produces, how long money takes to double, and the balance in today's money after inflation. A chart and year-by-year table show the growth curve, and you can copy or share any result.
Use it for high-yield savings accounts, CDs and fixed deposits, 401(k)s and IRAs in the US, ISAs and pensions in the UK, or any long-term investment. Investment returns vary from year to year, and taxes and fees aren't included.