Concept · C:effective-annual-rate

Effective annual rate

Working definition

The one-year growth rate that incorporates the effect of compounding at the declared periodic rate for the declared number of intervals in a year.

Also calledEffective annual yield · EAR

For a 6% stated annual rate compounded monthly:

(1 + 0.06/12)^12 - 1 = 0.0616778… = 6.1678…%

The effective annual rate exceeds 6% because each month's growth remains in the base for later months. At annual compounding, stated and effective annual rates are equal under this convention. At a zero rate, both are zero.

Keep the three labels separate in a workpaper: the stated annual quote, the rate applied in each period, and the effective growth over one year. Record the number of compounding intervals beside them. This small table prevents a monthly rate from being presented as an annual result or an annual quote from being applied twelve times without conversion.

EAR can align the annual compounding effect of otherwise comparable quotes. It does not automatically include fees, cash-flow timing differences, taxes, credit risk, liquidity, product options, or legal disclosure rules. Equal EARs also do not make two products identical.

Keep at least full calculator precision through the comparison and round only the displayed percentage. Early rounding of the monthly rate can materially distort a long horizon.

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Understand this concept

  • Explain effective annual rate as one-year compounded growth and distinguish it from the stated quote and periodic rate.
Learning level

Apply this concept

  • Compute an effective annual rate from a declared stated quote and frequency, then compare only alternatives with aligned horizons and included terms.

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Updated Sep 10, 2026 Review due Nov 7, 2026