Compound Interest Calculator
Calculate investment growth over time with compounding.
Compound Interest Calculator
Watch your money grow over time
Increase contributions by this % each year
About the Compound Interest Calculator
Investment calculators for compound interest, ROI, FIRE number, and dividend projections. All private, in-browser.
How to Use This Calculator
Plan your investments in five steps.
- 1
Enter your initial investment
Input the starting amount you are investing today.
- 2
Add regular contributions
Specify monthly or annual additions to your portfolio.
- 3
Set the expected return rate
Use 7–10% for equities, 6–8% for balanced portfolios.
- 4
Choose the time horizon
Longer horizons dramatically amplify compound growth.
- 5
Analyze your results
View projected balance, total contributions, and growth charts.
Key Features
Powerful features for investors at any level:
Compound growth projection
See year-by-year growth with compounding.
Regular contribution modeling
Add monthly, quarterly, or annual contributions.
Inflation-adjusted returns
Toggle between nominal and real returns.
Interactive growth charts
Visualize principal vs interest over time.
Multiple compounding frequencies
Daily, monthly, quarterly, or annual compounding.
100% private
No account required — data stays on your device.
The Power of Compound Interest
A = P(1 + r/n)^(nt). $10K at 10% compounded monthly becomes $198K in 30 years. Add $500/month and it reaches $1.24M. Starting 10 years earlier can more than double your balance.
Investment Scenarios & Examples
Real investment planning examples:
Retirement nest egg
$500/month at 8% for 30 years = $745K. 40 years = $1.75M.
FIRE number
$50K annual expenses = $1.25M FIRE number (×25).
DCA vs lump sum
Lump sum beats DCA ~68% of the time, but DCA reduces timing risk.
Dividend reinvestment
$100K at 3% yield with DRIP = $243K vs $190K without — 28% more.
Smart Investing Tips
Proven strategies to maximize returns:
Start early
$200/month from age 25 beats $500/month from age 35.
Use dollar-cost averaging
Fixed amounts at regular intervals reduces timing risk.
Keep fees low
A 1% fee on $500K costs $5K/year. Index funds at 0.03% save thousands.
Diversify
A 60/40 portfolio has returned 6–8% with lower volatility.
Rebalance annually
Review allocation yearly to maintain your target mix.
Investment Pitfalls to Avoid
Common mistakes that hurt your portfolio:
Unrealistic returns
Never assume more than 10–12% for long-term planning.
Ignoring inflation
10% nominal with 3% inflation = only 7% real return.
Emotional investing
Selling during downturns locks in losses — stay the course.
Chasing past performance
Last year's winner is often next year's loser. Choose index funds.
Overlooking tax efficiency
Hold bonds and REITs in tax-advantaged accounts.
Expert Tips
Maximize employer 401k match
An instant 50% return — do not leave it on the table.
Use tax-advantaged accounts first
Max out IRA ($7K) and 401k ($23.5K) before taxable accounts.
Build an emergency fund first
Keep 3–6 months of expenses before investing.
Common Questions
What return rate should I assume?
How is compound interest calculated?
What is the 4% rule for FIRE?
More Investment & Wealth Calculators
SIP Calculator
Systematic investment plan returns projection.
ROI Calculator
Measure return on investment with precise metrics.
Dividend Calculator
Calculate dividend yield and reinvestment growth.
DCA Calculator
Dollar-cost averaging strategy simulator.
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