Is this calculator accurate for financial planning?

This calculator provides estimates based on the formulas and inputs provided. For important financial decisions, please consult with a qualified financial advisor.

Can I solve for different variables?

Yes! This calculator supports reverse solving. You can solve for: Principal, Annual interest rate, Time period, Future value.

What units can I use?

This calculator supports multiple unit systems. Select your preferred units from the dropdown menus next to each input field.

Compound Interest Calculator

Calculate future value, principal, interest rate, or time for compound interest investments

Formula shown4 inputs definedUpdated Nov 2025By CalcuTotal TeamFree, no sign-up

Quick Summary

Use this when you need:

Get accurate results in seconds
Plan investments or compare returns
Solve for any unknown variable

You’ll need:Principal, Annual interest rate, Compounds per year, Time period

You’ll get:Future value

Results may be approximate for complex calculations

How this is calculated

The formula is always visible so you can verify the math and explain your numbers to anyone who asks.

What these terms mean

Principal

Principal used in the calculation.

Annual interest rate

Annual interest rate used in the calculation.

Compounds per year

Compounds per year used in the calculation.

Time period

Time period used in the calculation.

Future value

Future value used in the calculation.

When to use this calculator

Use this calculator when you need to quickly compute compound interest calculator with accurate, verified formulas.

Last updated: November 19, 2025

Compound interest calculator explained

Compound interest multiplies your balance by $(1 + r/n)^{n t}$ , so earnings in one period themselves earn interest later. This calculator solves for future value, principal, rate, or time, letting you compare monthly, quarterly, or even daily compounding schedules.

How the conversion works

The core formula is:

FV = P \\left(1 + \\frac{r}{n}\\right)^{n t}

where $P$ is principal, $r$ is the annual rate (decimal), $n$ is compounds per year, and $t$ is years. Rearranging lets us compute whatever variable is missing. For example, the time needed to reach a goal is

t = \\frac{\\ln(FV / P)}{n \\ln\\left(1 + r/n\\right)}

Units and conversions

Variable	Meaning	Notes
$P$	Principal	Starting deposit.
$r$	Annual nominal rate (%)	Enter APR; the tool converts to decimal automatically.
$n$	Compounds per year	12 for monthly, 365 for daily.
$t$	Time	Enter years or months (converted to years).
$FV$	Future value	Ending balance.

Worked examples

Future value with monthly compounding
$P = 10{,}000$ , $r = 5\\%$ , $n = 12$ , $t = 10$ years.

FV = 10{,}000 \\left(1 + 0.05/12\\right)^{120} = 16{,}470.09

Required rate to double in 10 years
$P = 10{,}000$ , $FV = 20{,}000$ , $n = 12$ , $t = 10$ .

r = n \\left(\\left(\\frac{FV}{P}\\right)^{1/(n t)} - 1\\right) = 6.95\\%

Tips and pitfalls

Actual investment returns fluctuate; use this calculator for deterministic projections, not guarantees.
Effective annual rate (EAR) equals $(1 + r/n)^n - 1$ and is higher than the nominal APR when compounding more than once per year.
When comparing savings accounts, convert all offers to the same compounding frequency to avoid apples-to-oranges decisions.
Taxes and fees reduce realized growth; add them separately if needed.

References and further reading

Frequently Asked Questions

Financial Disclaimer

This calculator provides estimates for informational purposes only and should not be considered financial advice.

The calculations are based on the inputs you provide and standard financial formulas. Actual results may vary based on factors not included in this calculator.

While we strive for accuracy, we recommend verifying results with a financial professional for important decisions.

We do not guarantee the accuracy, completeness, or applicability of any calculations to your specific situation.

Past performance does not guarantee future results. All investments carry risk.

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Calculator info

Version:: v1.0.0
Last reviewed:: Nov 13, 2025
Sensitivity:: medium
References:: 1

Last updated: November 19, 2025

Compound interest calculator explained

How the conversion works

The core formula is:

FV = P \\left(1 + \\frac{r}{n}\\right)^{n t}

t = \\frac{\\ln(FV / P)}{n \\ln\\left(1 + r/n\\right)}

Units and conversions

Variable	Meaning	Notes
$P$	Principal	Starting deposit.
$r$	Annual nominal rate (%)	Enter APR; the tool converts to decimal automatically.
$n$	Compounds per year	12 for monthly, 365 for daily.
$t$	Time	Enter years or months (converted to years).
$FV$	Future value	Ending balance.

Worked examples

Future value with monthly compounding
$P = 10{,}000$ , $r = 5\\%$ , $n = 12$ , $t = 10$ years.

FV = 10{,}000 \\left(1 + 0.05/12\\right)^{120} = 16{,}470.09

Required rate to double in 10 years
$P = 10{,}000$ , $FV = 20{,}000$ , $n = 12$ , $t = 10$ .

r = n \\left(\\left(\\frac{FV}{P}\\right)^{1/(n t)} - 1\\right) = 6.95\\%

Tips and pitfalls

Actual investment returns fluctuate; use this calculator for deterministic projections, not guarantees.
Effective annual rate (EAR) equals $(1 + r/n)^n - 1$ and is higher than the nominal APR when compounding more than once per year.
When comparing savings accounts, convert all offers to the same compounding frequency to avoid apples-to-oranges decisions.
Taxes and fees reduce realized growth; add them separately if needed.

Quick Summary

Calculator Tool

How this is calculated

What these terms mean

Principal

Annual interest rate

Compounds per year

Time period

Future value

When to use this calculator

Compound interest calculator explained

How the conversion works

Units and conversions

Worked examples

Tips and pitfalls

References and further reading

Frequently Asked Questions

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Financial Disclaimer

Was this calculator helpful?

Found an error?

Calculator info

Compound interest calculator explained

How the conversion works

Units and conversions

Worked examples

Tips and pitfalls

References and further reading

Frequently Asked Questions

Related Calculators

Simple Interest Calculator

Circle Circumference Calculator

Ohm's Law Calculator

Cents to Dollars Calculator

Cents to Euros Calculator

Dimes to Dollars Calculator

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