APY Calculator

Convert a nominal annual rate into APY from the selected compounding frequency, then compare effective yields and ending balances.

APR to APY comparison Compare how the same nominal annual rate compounds under different frequencies, then see the effective annual yield and ending balance side by side.

Display currency

Switch the display currency for the balance and interest comparisons without changing the APY maths.

Assumptions

This planner holds the nominal annual rate constant, assumes interest remains on deposit, and compares compounding frequency only. It does not model taxes, fees, tiered rates, or withdrawals.

Result

4.59% APY

Monthly compounding turns a nominal 4.5% rate into an effective annual yield of 4.59%.

Selected compounding

Monthly

Ending balance $12,517.96 after 5 years, with total interest of $2,517.96.

Annual-compounding baseline

+$56.14

Difference in ending balance versus annual compounding at the same nominal rate and holding period.

One-year nominal interest
$450.00
One-year APY interest
$459.40
Rate lift over APR
0.09%
Growth multiple
1.25x

Effective-return comparison

FrequencyAPYEnding balanceTotal interest
Annually 4.5%$12,461.82$2,461.82
Semi-annually 4.55%$12,492.03$2,492.03
Quarterly 4.58%$12,507.51$2,507.51
Monthly Selected4.59%$12,517.96$2,517.96
Daily 4.6%$12,523.05$2,523.05

How to use this result

APY is the cleaner shopping number when the goal is to compare savings products or deposit rates with different compounding rules. If fees, tiered balances, teaser rates, or mandatory payouts apply, compare this estimate with the official account disclosure before relying on it.

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Deposit Yield Basics

APY calculator guide: effective annual yield from a nominal rate and compounding frequency

An APY calculator converts a nominal annual rate into an annual percentage yield by accounting for how often interest compounds. It is useful when two savings products quote similar rates but compound on different schedules, because the frequency of compounding changes the effective yearly return.

APR, nominal rate, and APY are not the same thing

For deposit products, APY is the standardised annual-yield figure designed to reflect the effect of compounding. A nominal annual rate on its own does not tell the full earnings story unless you also know how often interest is added back to the balance.

That is why this calculator asks for a nominal annual rate, a compounding frequency, and an optional holding period. It then converts that rate into an APY and shows how the same balance grows under different compounding schedules.

Core APY maths

The effective annual yield is found by converting the nominal annual rate into a per-period rate, then compounding it across a full year. More frequent compounding usually produces a slightly higher APY, even when the headline nominal rate stays the same.

Once APY is known, the difference between the nominal rate and the effective yield becomes easier to compare across savings accounts, CDs, or other deposit-style products.

APY = (1 + r / n)^n - 1

r is the nominal annual rate and n is the number of compounding periods in one year.

Ending balance = Deposit x (1 + r / n)^(n x years)

Projects the balance forward under the selected compounding frequency and holding period.

Worked example: 10,000 at a 4.5% nominal annual rate

Suppose a deposit starts at 10,000 and the nominal annual rate is 4.5%. With annual compounding, the APY remains 4.5%. With monthly compounding, the APY is slightly higher because interest is added back to the balance twelve times during the year.

That gap may look small, but it becomes more visible when balances are larger or when the money remains on deposit for multiple years. The comparison table is designed to make that effect explicit without pretending that compounding frequency is the only thing that matters.

What this estimate excludes

This calculator isolates the compounding effect only. It does not model stepped rates, teaser rates, variable-rate products, taxes, account fees, or cases where interest is withdrawn instead of left on deposit.

Use it as a shopping and planning tool, then compare the result with the official account disclosure because real products may carry additional conditions that change the return you actually receive.

Further reading

Frequently asked questions

Why is APY usually higher than the nominal annual rate?

Because APY includes the effect of compounding within the year. When interest is added back to the balance more than once a year, later interest periods earn interest on earlier interest too.

 Is APY the best rate to compare for savings accounts?

Usually yes, because APY is designed as a standardized consumer-disclosure figure for deposit yields. It gives a cleaner like-for-like comparison than a nominal annual rate alone.

 Does withdrawing interest change the real return?

Yes. If interest is not left on deposit, the account may not earn the full APY because the compounding assumption is broken. That is one reason account disclosures matter.

 Does this calculator work for loans too?

Not directly. This page is designed around deposit-style compounding and APY. Loan comparisons often rely on APR or other disclosure rules instead.

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