What does compounding frequency mean?

It is how often the nominal annual rate is applied to accumulated principal and growth.

Are contributions included in compound growth?

Yes. Each contribution grows only after it enters the modeled balance.

What happens at a zero rate?

The ending balance equals the starting principal plus all contributions, and projected growth is zero.

Does currency selection convert money?

No. It changes the symbol and number formatting only.

Are fees, taxes or withdrawals modeled?

No. Subtract them from your assumptions separately if they matter to your scenario.

Compound Interest with Recurring Contributions

Model principal, cash additions and compounding frequency without assuming a product or promising a return.

Contribution-versus-growth breakdown

Beginning or end timing

Year-end summary

CurrencyStarting principalThe balance at the start of the projection.Nominal annual rateA hypothetical rate you supply; not a quoted or promised return.YearsCompounding frequencyContribution each periodContribution frequencyContribution timing

How to Build a Compound-Growth Scenario

Use one currency throughout. Enter a hypothetical nominal annual rate and cash-flow schedule that match the scenario you want to inspect.

Select a display currency; no exchange conversion is performed.

Timing changes the math

A beginning-of-period contribution receives one additional contribution period of growth compared with the same end-of-period contribution.

A Cash-Flow Calculation, Not a Product Forecast

This page targets the mathematical compound-interest intent: principal plus optional recurring contributions, a nominal annual rate, compounding frequency and contribution timing. The model derives an effective growth factor for each evenly spaced contribution period. It keeps the entered rate constant and does not infer market returns, deposit rates, risk, taxes or fees. The currency selector changes formatting only.

Compound Growth Examples

Lump sum with monthly compounding

Entered cash flows

principal:10000

annualRate:5%

years:10

compoundsPerYear:12

recurringContribution:0

Projected ending balance

$16,470.09

The balance uses 120 monthly compounding periods and no additional cash flows.

Monthly contributions

Entered cash flows

principal:1000

annualRate:6%

years:2

recurringContribution:100

contributionTiming:end

Projected ending balance

$3,670.36

$3,400 is principal plus contributions; $270.36 is mathematical growth under the fixed-rate assumption.

Compare assumptions

Change one input at a time to see whether rate, time, frequency or contributions caused the difference.

Frequently Asked Questions

No. It is a hypothetical input, not a quote, forecast or promise.

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Compound Interest and Contribution Formula

The implementation applies one consistent effective rate to each contribution interval and explicitly handles a zero rate.

Formula

A = P(1 + r/n)^(nt)

Principal growth

A = P(1 + r/n)^(nt)

Contribution-period rate

i = (1 + r/n)^(n/f) − 1

Period update

end timing: Bₖ = Bₖ₋₁(1+i)+C; beginning timing: Bₖ = (Bₖ₋₁+C)(1+i)

Scientific Background

Investor.gov describes compound interest as interest earned on principal and accumulated interest. This implementation is deterministic and uses only the assumptions entered.