Compound Interest & Savings Calculator
InstantSee how your savings grow with compound interest. Enter a starting amount, optional regular contributions, interest rate, compounding frequency, and term to project the future value and total interest earned.
Your savings plan
Projection
Future value
$145,180.47
Total contributions
$58,000
Interest earned
$87,180.47
Growth over time
How the math works
Lump sum: A = P × (1 + r/n)^(n·t)
With deposits: add the future value of each contributionP is the starting principal, r the annual rate, n the number of compounding periods per year, and t the number of years. Compounding more frequently (daily vs yearly) increases growth because interest is added to the balance sooner and then earns its own interest. Regular monthly contributions are added to the balance and compound alongside the principal.
Why compounding matters
The earlier you start, the more time your money has to compound. Even modest monthly contributions can grow substantially over decades because the interest earned each period itself earns interest in every period that follows.
Frequently asked questions
What is compound interest?+
Compound interest is interest earned on both your original principal and the interest already added. Because interest earns its own interest, savings grow faster over time than with simple interest.
How does compounding frequency affect growth?+
The more often interest compounds (daily vs monthly vs yearly), the more you earn, because interest is added to the balance sooner and starts earning its own interest.
What is the formula for compound interest?+
For a lump sum: A = P × (1 + r/n)^(n×t), where P is principal, r is the annual rate, n is compounds per year, and t is years. Regular contributions add a future-value-of-an-annuity term on top.