📈 Wealth Growth & Compound Interest
Compound Interest & Investment Calculator
Calculate your investment's future value with regular monthly contributions and exponential compounding growth.
Investment Profiles:
📈 S&P 500 Index ($10k + $500/mo @ 8% 20y)
🏖️ Long-term Retirement ($5k + $250/mo @ 7% 30y)
🏦 High-Yield Savings ($20k Lump Sum @ 4.5% 5y)
🚀 Growth Portfolio ($1k + $100/mo @ 10% 15y)
Future Investment Portfolio Value
$224,198.81
Portfolio Breakdown:
Initial Principal
$10,000.00
Total Contributions
$72,000.00
Compound Interest
$142,198.81
Years to Double (Rule 72)
9.0 years
Year-by-Year Growth Table:
| Year | Total Deposits | Interest This Year | Total Interest Earned | Ending Portfolio Balance |
|---|
The Power of Compound Interest & Exponential Growth
Compound interest is the process where interest is calculated not only on the initial principal but also on the accumulated interest from preceding periods. Unlike simple interest—which grows linearly—compound interest grows exponentially over long investment horizons.
The Rule of 72 Shortcut
The Rule of 72 is a mental math formula that estimates how many years it will take to double your money at a specified annual compound interest rate:
Years to Double ≈ 72 ÷ Annual Interest Rate (%)
Example: At an 8% annual return, your money doubles in approximately 72 / 8 = 9 years.
Frequently Asked Questions
More frequent compounding (e.g. daily vs annual) yields slightly higher returns because accrued interest begins earning its own interest sooner. The effective annual rate (APY) reflects this compounding boost over the nominal stated APR rate.
Because compounding is exponential, the final decade of a multi-decade horizon generates vastly more wealth than the first decade. An investor who invests for 30 years often earns more total interest than someone who contributes double the monthly amount for only 15 years.