Updated Savings & Yield

APY Calculator

Convert APR to APY, APY to APR, and estimate how your savings grow over time with compound interest.

APR → APY APY → APR Compounding Effects Growth Projection

All-in-One APY Calculator

Compare nominal APR vs APY and see how compounding and time change your real return.

APY assumes you leave your money invested for a full year and reinvest interest at the same rate.

“Per period” means each compounding interval (e.g., monthly if compounding monthly).

APY Calculator – Understand Your Real Investment Return

This APY Calculator shows how compounding turns a nominal interest rate (APR) into a higher effective annual yield (APY). You can convert APR to APY, APY to APR, and estimate how your savings or investments grow over time with compound interest.

What Is APY?

APY (Annual Percentage Yield) is the actual annual return you earn on your money after taking compounding into account. If a bank quotes you a rate like 4.50% APY, it means that after one year of compounding, your money effectively grows by 4.50%, even if the nominal APR is slightly lower.

APY Formula from APR

When you know the nominal rate (APR) and the number of compounding periods per year n, APY is:

APY = (1 + r / n)n − 1

Where r is the APR expressed as a decimal (for example 5% → 0.05), and n is how many times interest is compounded each year (12 for monthly, 365 for daily, etc.).

APR from APY

If you know APY and want to find the equivalent nominal APR with the same compounding frequency:

APR = n × [(1 + APY)1/n − 1]

This is useful when you want to compare products that advertise APY versus those that quote only nominal APR.

Growth Projection with APY

In the Growth Projection tab, the calculator uses your APY, compounding frequency, initial deposit, and regular contributions per period to estimate:

  • Final balance at the end of the chosen time horizon
  • Total amount you contributed
  • Total interest earned through compounding

Behind the scenes, the calculator applies the standard compound growth formula plus an annuity formula for contributions:

Final Balance = P(1 + i)N + C × \frac{(1 + i)N − 1}{i}

Where P is your initial deposit, C is your contribution each period, i is the interest rate per period, and N is the total number of periods.

How to Use This APY Calculator

  • Use APY Calculator when you have a nominal rate (APR) plus a compounding frequency and want to see the true APY.
  • Use APR → APY to compare different savings accounts, CDs, or investment products with different compounding frequencies.
  • Use APY → APR if your bank only shows APY and you want to know the underlying nominal rate.
  • Use Growth Projection to visualize how your savings can grow over time when you add regular contributions on top of your starting balance.

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