Compound Interest Calculator
See how your money can grow over time with the power of compounding. Add regular contributions to accelerate growth. All calculations are done locally in your browser.
What is Compound Interest?
Compound interest is interest calculated on the initial principal and also on the accumulated interest of previous periods. It's often called "interest on interest" and makes your money grow exponentially over time. The more frequently interest is compounded, the faster your savings grow. Even small, regular contributions can build a substantial nest egg thanks to the power of compounding.
The Compound Interest Formula
The standard formula for compound interest with regular contributions is:
A = P(1 + r/n)nt + PMT × [((1 + r/n)nt - 1) / (r/n)]
- A = final amount (future value)
- P = initial principal
- r = annual interest rate (decimal)
- n = compounding periods per year
- t = time in years
- PMT = periodic contribution
Our calculator handles all these variables. Simply enter your numbers and see the results instantly.
How to Use the Compound Interest Calculator
- Enter your starting principal – the amount you are investing now.
- Add a monthly contribution (optional) – set an amount you plan to invest every month.
- Choose the contribution timing – at the beginning or end of each month.
- Enter the annual interest rate – the expected rate of return on your investment.
- Select the compounding frequency – how often interest is calculated (daily, monthly, annually, etc.).
- Set the number of years – how long you plan to let your money grow.
- Click "Calculate Growth" – the future value, total contributions, and interest earned are displayed, along with a year‑by‑year breakdown.
The calculator works with any currency – you can use the ₹ symbol as a placeholder for your own currency.
Why Use Our Compound Interest Calculator?
- 100% free & private – No sign‑up, no data collection. All calculations run locally in your browser.
- Flexible inputs – Supports any compounding frequency from daily to annually, and contributions at the start or end of the period.
- Detailed breakdown – See year‑by‑year growth with contributions, interest, and balance columns.
- Works offline – Once the page is loaded, you can continue using the calculator without an internet connection.
- Educational – Understand how small changes in rate, time, or contributions affect your final outcome.
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on the initial principal and also on the accumulated interest of previous periods. It's often called "interest on interest" and makes your money grow faster over time.
How is compound interest calculated?
The formula is A = P(1 + r/n)^(nt) + [PMT × ((1 + r/n)^(nt) - 1) / (r/n)], where P = principal, r = annual rate, n = compounding periods per year, t = years, PMT = periodic contribution.
What does compounding frequency mean?
It determines how often the earned interest is added to the principal. Daily compounding adds interest every day, while annual compounding adds it once per year. More frequent compounding results in slightly higher returns.
Should I contribute at the start or end of the month?
Contributing at the start gives your money more time to compound, resulting in a slightly larger future value. Our tool lets you compare both options.
Is the compound interest calculator free?
Yes, it's completely free. No sign‑up or payment required. You can use it as often as you like.
Can I use this calculator offline?
Once the page is loaded, all processing is client‑side. You can calculate compound interest even without an internet connection.
Does this tool collect my data?
No. All inputs and calculations are performed directly in your browser. No information is ever stored or transmitted.
What is the difference between simple and compound interest?
Simple interest is calculated only on the principal, while compound interest includes interest on previously earned interest. Over long periods, compound interest yields significantly more.
Can I use this calculator for loan interest?
This tool is designed for savings and investment growth. For loan interest, you may want to use an EMI or loan calculator.
What is the future value?
The future value is the total amount your investment will be worth at the end of the chosen period, including both contributions and interest earned.
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