Finance Tools
Free Compound Interest Calculator — With Contributions & Growth Chart
See how your money grows with compound interest and regular contributions. Choose compounding frequency, see year-by-year growth and inflation-adjusted real returns.
Investment Details
$
%
years
Regular Contributions
$
$167,857
Future Value
$109,857
Total Interest
$58,000
Total Contributed
15.15%
CAGR
Wealth Breakdown
Contributions $58,000Interest earned $109,857
Growth Over Time
ContributionsInterest
How to Use the Compound Interest Calculator
1
Set your principal & rate
Enter your starting investment amount, the expected annual interest rate and your investment timeframe in years.
2
Choose compounding frequency
Select how often interest compounds — from annually to daily. More frequent compounding slightly increases returns.
3
Add regular contributions
Enter a monthly, quarterly or annual contribution to see how regular investing dramatically accelerates growth.
4
Enable inflation adjustment
Toggle inflation to see the real purchasing power of your future balance in today's dollars — important for retirement planning.
❓ Frequently Asked Questions
What is the difference between simple and compound interest?+
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus all previously earned interest — meaning your earnings generate their own earnings. This 'interest on interest' effect is why Albert Einstein allegedly called compound interest the eighth wonder of the world. Over long periods, the difference is enormous: $10,000 at 8% simple interest for 30 years grows to $34,000; with compound interest it grows to over $100,000.
How does compounding frequency affect my returns?+
More frequent compounding means slightly higher returns, because each compounding period, your interest is added to the principal and begins earning its own interest sooner. Daily compounding vs annual compounding on $10,000 at 10% for 10 years: annual gives $25,937; daily gives $27,179 — about 5% more. The difference between monthly and daily is minimal for most investors. What matters far more is the interest rate and how long you stay invested.
What are regular contributions and why do they matter?+
Regular contributions are periodic additions to your investment — for example, investing $500 every month into an index fund. They matter enormously because they continuously add to the principal that earns compound returns. Our calculator shows the dramatic difference: $10,000 invested once at 8% for 30 years grows to $100,626. The same $10,000 plus $200/month at 8% for 30 years grows to $370,422 — nearly 4× more, from just $200 extra per month.
What is CAGR and how is it calculated?+
CAGR (Compound Annual Growth Rate) is the rate at which an investment grows from its initial value to its final value, as if it grew at a steady rate every year. Formula: CAGR = (End Value / Start Value)^(1/Years) - 1. CAGR is useful for comparing investments of different lengths or with irregular returns. An investment that grew from $1,000 to $3,000 in 10 years has a CAGR of 11.6%, meaning it effectively grew 11.6% per year on average.
How does inflation affect the real value of compound interest returns?+
Inflation erodes the purchasing power of your future returns. If your investment earns 8% annually but inflation runs at 3%, your real return is approximately 5% (known as the real rate of return). Our inflation-adjusted calculation shows you the true purchasing power of your future wealth in today's dollars. For long-term planning, real returns matter more than nominal returns — a 10% return in a 9% inflation environment barely keeps pace with rising prices.