The most powerful Cumulative Interest Calculator on the web
See exactly how your money grows. Calculate compound interest on savings, investments, and recurring deposits — with real-time charts, inflation adjustments, tax modeling, and a complete year-by-year schedule.
- 8 compounding frequencies
- Inflation & tax adjustments
- Year-by-year schedule
- Step-up contributions
- CSV export
- Shareable scenario URLs
Cumulative Interest Calculator
Final Balance
$170,619.05
Total Contributions
$70,000
Total Interest
$100,619
Effective APY
7.23%
Growth Over Time
Final Balance Breakdown
Key Insights
Time is your biggest asset
Over 20 years, your money grows 17.1 times.
Interest does the heavy lifting
58.97% of your final balance comes from interest, not deposits.
Compounding frequency matters
Compounding monthly gives you an effective rate of 7.23% per year.
Inflation erodes purchasing power
In today's money, your final balance is worth $104,123.85.
Year-by-Year Schedule
Calculations update instantly.
Built for every kind of saver and investor
Use the right calculator for your situation. All free, all instant, all in your browser.
Long-term savings
Forecast how a high-yield savings account or CD will grow with regular deposits.
Try itInvestment growth
Project portfolio outcomes with realistic returns, inflation, and step-up SIPs.
Try itLoan payoff strategy
Visualize the cumulative interest on a mortgage or loan, and see savings from extra payments.
Try itReach a financial goal
Reverse-solve for the rate, time, principal, or contribution to hit a target wealth.
Try itRetirement planning
Model decades of compounding with annual contribution increases and inflation.
Try itCompare scenarios
Pit conservative, balanced, and aggressive plans against each other on one chart.
Try itWhat is cumulative interest, really?
Cumulative interest is the running total of all interest you earn (or pay) across an investment or loan. Each period, interest is added to your balance — and in the next period, you earn interest on that new, larger balance. That snowball effect is called compounding, and the cumulative interest figure tells you exactly how much wealth compounding has created for you.
For example, $10,000 invested at 7% annually for 20 years grows to about $40,000 — but $30,000 of that is cumulative interest. That's three times your original deposit, earned purely through patient compounding. Our calculator shows you the full picture: how much comes from your principal, your contributions, and your earned interest, year by year.
Read the full guide →Why this calculator stands out
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Real-world realism
Models inflation, taxes on interest, and step-up contributions — most calculators don't.
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Privacy-first
100% client-side. We never see your numbers, and there's no sign-up or tracking inside the calculator.
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Mobile-first design
Works flawlessly on phones, tablets, and desktops with offline-capable static delivery.
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Shareable & exportable
One-click share via URL or download a year-by-year CSV for spreadsheets.
Cumulative Interest — FAQ
What is a cumulative interest calculator?
How is cumulative interest different from compound interest?
What is the formula for cumulative interest with regular contributions?
A = P(1 + r/n)^(nt). With recurring contributions: FV = P(1+r/n)^(nt) + PMT × [((1+r/n)^(nt) − 1) / (r/n)], where P is principal, r is annual rate, n is compoundings per year, t is time in years, and PMT is the periodic deposit. Cumulative interest = FV − P − total contributions.