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Compound Interest Calculator

Project how a lump sum grows with compound interest, optional recurring contributions, and your chosen compounding frequency.

Instantcalculation Contributionsoptional No sign-uprequired Educationalestimate only

Calculate compound growth

Enter principal, rate, time, and optional recurring contributions.

Use the same currency for all money fields. Recurring contribution uses the selected compounding period (e.g. $/month when monthly is selected). Actual investment returns are not fixed and may vary year to year. Results are estimates and do not include taxes, fees, inflation, or withdrawals.

Future value
—

Instant browser-based estimate

Total contributions —
Interest / growth earned —
Initial amount —
Recurring contribution total —
Growth multiple —
Effective annual rate —

Future value breakdown

Initial amount —
Total recurring contributions —
Interest / growth earned —
Final value —

Educational estimate only. Not financial advice. Assumes a constant rate and regular contributions.

Compound interest formula

Lump sum future value = P × (1 + r/n)^(n×t)

P = initial principal

r = annual rate as decimal

n = compounding periods per year

t = number of years

The calculator adds the future value of recurring contributions based on the selected compounding period. Each deposit compounds for the remaining periods in the term.

Compound interest calculator examples

Lump sum

$10,000 · 7% annual · monthly · 10 years · $0 recurring

Future value ~$20,097

A single deposit compounding monthly at 7% roughly doubles over 10 years in this estimate—growth earned is about $10,097.

Monthly contribution

$10,000 initial · $200/month · 7% · 10 years

Future value ~$54,714

Total contributions ~$34,000. Growth earned ~$20,714 above what was deposited—recurring contributions accelerate compounding.

Long-term compounding

$5,000 initial · $100/month · 8% · 20 years

Future value ~$83,536 · 2.88×

Longer horizons and steady contributions can produce large estimated balances—but real returns are not constant.

How to read the result

  • Future value is the estimated ending amount after compounding and contributions.
  • Total contributions are the dollars you put in—initial amount plus all recurring deposits.
  • Interest / growth earned is the estimated amount above your contributions.
  • Higher rates, longer periods, and more frequent contributions can increase the final estimate.
  • Real market returns are not constant—year-to-year results usually differ from a smooth compounding path.

Compound interest vs CAGR vs DCA

Compound interest calculator

Projects forward using an assumed annual return rate, compounding frequency, and optional recurring contributions.

Use this calculator →

CAGR calculator

Measures annualized growth between a known start value and end value over a completed period.

Open CAGR calculator →

DCA calculator

Models repeated contributions into an asset or scenario with historical or assumed prices.

Open DCA calculator →

ROI calculator

Measures simple profit/loss and percentage return from buy price, sell price, and optional fees.

Open ROI calculator →
  • Total return shows the full gain or loss over a period; CAGR annualizes it.
  • Two scenarios can share similar total growth but differ in CAGR if time periods differ.
  • None of these tools show volatility, drawdown, or the path of returns—use together for context.

When to use this calculator

  • Estimate long-term growth from a fixed assumed annual return
  • Compare lump-sum vs recurring contribution scenarios
  • Understand how time and compounding frequency affect estimates
  • Model savings or investment scenarios for educational planning
  • Compare different annual return assumptions side by side

This calculator uses a fixed annual rate. It does not predict actual market returns. Pair results with drawdown and volatility context from our Learn guides.

What is compound interest?

Compound interest is growth on your principal plus previously earned interest. Each compounding period, earnings are reinvested so the balance can accelerate over time compared with simple interest.

This educational calculator works for savings, investments, and planning scenarios when you want to estimate future value from an assumed rate—not from live market data.

How compound interest works

  • The initial amount compounds at the rate divided by compounding frequency.
  • Each recurring contribution compounds for the remaining periods.
  • Future value = compounded principal + future value of the contribution stream.
  • Effective annual rate reflects how often compounding occurs at the nominal rate.

Assumes no withdrawals and no change in the annual rate. Does not model taxes, fees, or inflation.

Limitations of compound interest calculators

  • Uses a constant annual return—real markets vary year to year.
  • Does not show volatility, drawdowns, or sequence-of-returns risk.
  • Recurring contributions use the compounding period—not a separate contribution schedule.
  • Excludes taxes, fees, inflation, and partial withdrawals.
  • Past or assumed rates do not guarantee future results.

Frequently asked questions

What is compound interest?
Compound interest is growth on both your principal and previously earned interest. Each compounding period, earnings are reinvested so the balance can grow faster over time than simple interest alone.
How do I calculate compound interest?
For a lump sum: FV = P × (1 + r/n)^(n×t). With recurring contributions, the calculator adds the future value of each deposit. Enter your values above for an instant estimate.
What compounding frequency should I use?
Use what matches the product or scenario: savings accounts often compound monthly or daily; many projections use monthly or annual compounding. More frequent compounding slightly increases the effective return at the same nominal rate.
Does this calculator support recurring contributions?
Yes. Enter a recurring amount per compounding period—for example, $200 per month when monthly compounding is selected. Contributions use the same period as compounding.
Is compound interest the same as CAGR?
No. This calculator projects forward from an assumed rate. CAGR measures annualized growth between a known start and end value. Use both for different questions.
Does this work for investments with variable returns?
You can enter an assumed average annual return for illustration, but real market returns vary year to year. This tool uses a fixed rate and does not model volatility or drawdowns.
Does this calculator include taxes, fees, or inflation?
No. Results are estimates before taxes, fees, inflation, and withdrawals unless you adjust inputs manually.
Is this compound interest calculator free?
Yes. No sign-up is required. Calculations run locally in your browser; inputs are not sent to our servers.
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Past performance does not predict future results. CalculatorInvest provides educational tools only—not financial advice. Read our disclaimer.