Compound Interest Calculator
Estimate how your money could grow over time when interest is added to your balance and earns additional interest.
Enter Your Numbers
The starting amount of money you are investing or saving.
The annual interest rate expressed as a percentage.
How long the money remains invested or saved.
How often interest is added to the balance.
What Is Compound Interest?
Compound interest is interest calculated on your original money as well as interest that has already been added to the balance.
Because previously earned interest can also earn interest, the effect can become more significant as time passes.
Compound Interest Formula
A = final balance
P = initial principal or investment
r = annual interest rate expressed as a decimal
n = number of compounding periods per year
t = number of years
Why Does Compounding Matter?
Compounding can make a major difference over longer periods because interest that has already been earned remains part of the balance used for future calculations.
The effect depends on factors such as the starting amount, interest rate, time period, and compounding frequency.
Time can make a difference
A longer investment period gives compounding more time to affect the balance. However, actual investment returns are never guaranteed.
Compound Interest Example
Suppose you invest $1,000 at an annual interest rate of 5% for 10 years and the interest compounds monthly.
Initial investment: $1,000
Annual interest rate: 5%
Time: 10 years
Compounding: Monthly
The calculator estimates the resulting balance and the total interest earned.
What You Need to Enter
Initial Investment
The amount you start with. This can represent an investment, savings balance, or another principal amount.
Annual Interest Rate
The yearly interest rate. Enter 5 for a 5% annual rate.
Time Period
The number of years the money remains invested or saved.
Compounding Frequency
How often interest is added to the balance. Common options include annually, quarterly, monthly, and daily.
Understanding Your Result
The Final Balance represents your starting amount plus the estimated compound interest.
The Total Interest Earned shows how much the balance increased through interest, before considering taxes, fees, inflation, or other factors.
If you are comparing real investments or savings products, check the actual terms, fees, taxes, and rates rather than relying only on a calculator estimate.
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on the original principal and on interest that has previously been added to the balance.
What is the difference between simple and compound interest?
Simple interest is calculated on the original principal, while compound interest can also apply to previously accumulated interest.
Does compound interest guarantee profit?
No. A calculator can estimate growth using a fixed rate, but real investments may have changing returns, fees, taxes, inflation, and the possibility of loss.
What does compounding frequency mean?
Compounding frequency describes how often interest is added to the balance. Common frequencies include annual, semi-annual, quarterly, monthly, and daily.
Is monthly compounding better than annual compounding?
When the stated annual rate and other assumptions are the same, more frequent compounding can produce a higher calculated balance. Actual financial products may use different rate structures and terms.
Can I use this calculator for savings?
Yes. You can use it to estimate how a starting savings balance could grow when a fixed interest rate is compounded over time.
Does this calculator include regular deposits?
No. This version calculates growth from an initial investment. A future savings calculator can be used for scenarios involving regular contributions.
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Important Disclaimer
This calculator provides estimates for educational and informational purposes only. Actual investment or savings results may differ because of changing rates, fees, taxes, inflation, market conditions, and other factors. This tool does not provide financial, investment, tax, accounting, or legal advice.