Compound Interest
See how investments grow over time with monthly contributions, inflation adjustment, and rate comparisons.
Free & unlimited
Initial investment ($)
Monthly contribution ($)
Annual interest rate (%)
Time period (years)
Compounding frequency
Quick rates
Future value
$54,714
Contributed
$34,000
Interest earned
$20,714
Final amount breakdown
Initial: $10,000
Contributions: $24,000
Interest: $20,714
Growth over time
Year 0Year 10
Contributions
Interest
Your $34,000 in contributions will grow to $54,714 over 10 years — that's 61% growth.
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About this tool
- 1
Enter your principal
Input the starting investment amount or current savings balance.
- 2
Set rate and period
Enter the annual interest rate and the number of years you plan to invest.
- 3
Choose compounding frequency
Select how often interest compounds: monthly, quarterly, semi-annually, annually, or continuously.
- 4
View the results
See the final balance, total interest earned, and a year-by-year growth chart.
- More frequent compounding (monthly vs annually) yields slightly more interest - but the difference shrinks at lower rates.
- The Rule of 72: divide 72 by your interest rate to estimate how many years it takes to double your money.
- Adding regular monthly contributions dramatically increases the final value - even small amounts compound significantly over decades.
- Inflation erodes purchasing power. Subtract the inflation rate from your return rate for a real (inflation-adjusted) estimate.
- Multiple compounding frequency options
- Optional regular monthly contribution input
- Year-by-year growth table and chart
- Total interest earned vs principal breakdown
- Inflation-adjusted result option
- Plan long-term savings and retirement investment growth.
- Compare different savings accounts by their compounding frequency.
- Visualize how regular monthly contributions accelerate wealth building.
- Understand the impact of interest rate differences over time.
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus all previously earned interest, so your money grows exponentially.
More frequent compounding means interest is calculated and added to the balance more often, so it earns interest on interest sooner. Monthly compounding at 6% yields about 6.17% effective annual rate vs 6% with annual compounding.
Continuous compounding uses the formula A = Pe^(rt), where interest is theoretically compounded infinitely often. In practice, the difference from daily compounding is negligible.
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