Compound Interest Calculator – Growth & Interest
Calculate final amount and interest earned using compound interest. Select compounding frequency and duration to see how your principal grows.
Compound Interest Calculator Form
Compound Interest Formula
Compound interest calculates how principal grows when interest is reinvested each compounding period. The standard formula gives the accumulated amount after t years.
Formula (mathematical):
A = P × (1 + r / n)n × t
Where:
- P = Principal (initial amount)
- r = Annual nominal interest rate (as a decimal)
- n = Number of compounding periods per year
- t = Time in years
- A = Accumulated amount after t years
Interest earned = A − P. Use this formula to compare how different compounding frequencies and rates affect growth.
Compounding Frequency Effect
| Frequency | Example |
|---|---|
| Annually | Interest added once per year |
| Monthly | Interest added each month — yields higher final amount than annual for same nominal rate |
This compound interest calculator computes the accumulated amount when interest is compounded at a chosen frequency. It is useful for bank deposits, bonds, savings, or any investment where interest is periodically reinvested. Enter your principal, annual rate, compounding frequency, and duration to see the final amount and interest earned.
When to use this calculator
Use it to estimate returns on fixed deposits, recurring bank products, or to model how savings grow over time under compound interest assumptions. It is helpful when comparing different banks or instruments with the same nominal rate but different compounding frequencies.
How it works (plain explanation)
The calculator converts the annual percentage into a decimal monthly/daily rate depending on chosen frequency and applies it repeatedly across the total number of compounding periods (n × t). More frequent compounding means interest is calculated on previously earned interest more often, increasing the final amount slightly compared to less frequent compounding.
Benefits & limitations
Compound interest demonstrates the power of reinvestment — small differences in rate or compounding frequency can matter over long durations. However, this basic model assumes a constant nominal rate and no additional deposits or withdrawals. For scenarios with periodic contributions or varying rates use a future-value-of-series or XIRR-style calculations.
Frequently asked questions
What is compound interest? Interest on both principal and accumulated interest over previous periods.
How often should interest be compounded? More frequent compounding (monthly/daily) yields a slightly higher amount than annual compounding for the same nominal rate.
Does it include additional deposits? No — this calculator assumes a single initial deposit. For recurring deposits use a SIP/savings calculator.
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Disclaimer: This calculator is for educational purposes only and does not constitute financial advice. Always consult a qualified advisor for investment decisions.