Tool 15

Investment calculators · Measured total return and explicit time conventions

Annualised Return Calculator

Created by Arunangshu DasReviewed Nov 5, 2026

Convert a measured holding-period return into an equivalent effective annual percentage. Choose years, months or supplied complete days and inspect the time fraction.

A mathematical scenario, not a forecast, product payment date or personalized financial advice. No separate fees, taxes or inflation adjustment.

Preparing calculator…

Your holding-period return

Positive starting capital. Supply one consistently measured total growth factor, including any reinvested distributions already reflected in it. No separate tax, fee, inflation or currency adjustment.

Total holding-period return (%)

Enter −100 through 1000; 21 means a total 21% gain, not 21% per year.

Duration unit

Changing units clears duration and its result.

Duration (years)

From 1/365 through 1000 model years. Whole supplied days only; no calendar dates or leap-year adjustment.

There were external deposits or withdrawals

This model supports no external cash flows. Use XIRR for dated cash flows or IRR for equal periods.

Use ungrouped decimal points and at most 12 fractional places. Blank is missing. Percentage inputs do not require a country or currency selection.

Equivalent effective annual return

Enter the measured return and horizon explicitly, or load the verified 21% over two years example.

120 significant decimal digits internally; half-even display at 6 places, scientific notation for tiny nonzero rates, and a greater-than −100% marker for near-complete loss. Positive annual factors outside 1e−30 through 1e10 are rejected. Inputs remain in browser memory; no financial values are saved or sent.

Interpret the annual equivalent

A short-period annualised figure is an extrapolation, not an observed yearly gain or a forecast. Use a consistently measured total growth factor; external cash flows require a different model.

Read the complete Annualised Return guide

Formula and methodology

A = 100×((1+H/100)^(1/T)−1).
T = years, months/12, or supplied days/divisor.
Positive capital; no external deposits or withdrawals.

Let T be the explicit horizon in model years. Solving annual factor raised to T equals the supplied total growth factor gives A=100×((1+H/100)^(1/T)−1). This is geometric annualisation. Dividing H by T is a linear scaling and generally does not reproduce the measured factor through compound growth.

Verified worked examples

For H=21 and T=2, the total factor is 1.21. Its positive square root is exactly 1.1, so the annual equivalent is 10%. A linear 21/2=10.5% would compound to 22.1025% over two years, rather than the supplied 21%. This difference comes from compounding, not a fee adjustment.

Inputs and interpretation

First establish what your source percentage measures: price growth or total return, gross or net of fees, and before or after taxes. Enter that number with an ungrouped decimal point. Select the duration unit, then enter the explicit duration. Changing units clears the duration so that two years cannot silently become two months.

Assumptions and limitations

No calendar start or end date is accepted. A supplied 366-day duration with divisor 365 is 366/365 model years; it is not automatically one leap year. Neither divisor implements actual/actual, a 30/360 date adjustment, trading-day annualisation or a bank interest-crediting schedule. Fractional years and months are numerical periods, not inferred calendar anniversaries.

Supported domain and common mistakes

Total return is limited to −100% through 1000%. The horizon must be at least 1/365 and at most 1000 model years. Supplied days must be complete integers. Decimal strings are trimmed, limited to 48 characters and 12 fractional places, with no grouping separators, percent signs or exponent notation. Zero or negative duration is invalid because annualisation requires a positive interval.

Do not annualise an already annualised rate again. Do not enter 21% for a two-year period and then describe the resulting 10% as the actual return earned in each year. Do not treat a nominal APR as this measured total return, or change the divisor merely to obtain a preferred result. The convention should match the question before calculation.

Frequently asked questions

What total return should I enter?

Enter the measured whole-period percentage, such as 21 for a total 21% gain. Use a consistent growth-factor basis and positive starting capital. Do not enter an already annualised rate.

Why does changing the duration unit clear the value?

Two years and two months are different horizons. The duration and stale result are cleared so you explicitly enter the new unit instead of silently changing its meaning.

Can I include external deposits or withdrawals?

No. Check the external cash-flow option to reject that scenario. IRR handles equal-period cash flows and XIRR handles dated cash flows; a balance change is not automatically an investment return.

What happens at zero return or complete loss?

Zero total return gives exactly zero annually. Exactly −100% gives a zero factor and a complete-loss endpoint result. A return below −100% is unsupported; near-complete loss is not silently rounded into complete loss.

Are supplied days adjusted for leap years?

No. They are divided by the selected fixed 365 or 360 numerical divisor. For example, 366/365 is more than one model year. There is no actual-date or bank accrual model.

Why can the tool reject a short-period scenario?

Very short horizons can create extreme annual factors. Positive annual factors outside 1e−30 through 1e10 are unsupported and rejected without clipping or showing a partial result.

Are my financial inputs stored or transmitted?

No. Calculation runs locally after loading. Inputs stay in browser memory and are not placed in URLs, saved to browser storage or sent for calculation.

Sources and educational scope

The Capital Intelligence provides financial calculators, educational content and analytical tools, not personalized investment advice. It is personally operated by Arunangshu Das, an individual in India. Inputs remain in browser memory; this calculator does not send financial values or save them to browser storage. A historical equivalent or hypothetical rate does not promise a future outcome.

Reviewed 2026-11-05. AI-assisted content under operator editorial responsibility; no independent expert financial review is claimed.