APY Calculator
Convert a nominal annual rate and compounding frequency into the real annual yield (APY).
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At a glance:The Annual Percentage Yield (APY) converts a nominal annual rate into the percentage you actually earn in a year after compounding: APY = (1 + nominal rate ÷ m)^m − 1, where m is the number of compounding periods per year. More frequent compounding raises the APY above the nominal rate. APY is the fair basis for comparing deposit or investment products with different compounding frequencies. APY is mathematically identical to the Effective Annual Rate (EAR).
Formula
APY = (1 + nominal rate ÷ m)^m − 1, where m is compounding periods per year.
The more frequent the compounding, the higher the APY above the nominal rate.
$$Annual Percentage Yield: $APY=\left(1+\dfrac{r}{m}\right)^{m}-1$$$$$where $r$ is the nominal annual rate and $m$ is the number of compounding periods per year.$$$$Example (5%, monthly): $\left(1+\dfrac{0.05}{12}\right)^{12}-1\approx5.1162\%$$$How to Use
- Enter the nominal annual rate quoted by the bank.
- Choose how often interest compounds each year (monthly, quarterly, etc.).
- The real annual yield APY is shown instantly.
FAQ
What is the difference between APY and the nominal annual rate (APR)? Which should I look at?
The key difference is whether compounding is counted. The nominal annual rate (often labelled APR or 'annual rate') is the most basic quote — it simply multiplies the periodic rate by the number of periods and does NOT account for interest being reinvested to earn further interest. APY (Annual Percentage Yield) fully counts the compounding effect and reflects 'the percentage you actually earn after one year'. Example: a nominal 5% compounded monthly is labelled 5%, but because each month's interest is reinvested, the real one-year return is about 5.1162% (the APY). The more frequent the compounding, the larger the gap above the nominal rate. For deposits and investments — where you are the one receiving interest — you should look at APY, because it is your actual annual return and the fair basis for comparing products with different compounding frequencies; the nominal rate alone can mislead. Note that in borrowing contexts (loans, credit cards) the comparable concept is the effective annual rate, which likewise counts compounding and fees; the principle is the same: whether you receive or pay interest, look at the actual annual rate after compounding, not the surface figure.
Is APY the same thing as EAR (Effective Annual Rate)?
Yes. APY (Annual Percentage Yield) and EAR (Effective Annual Rate) are mathematically identical — the formula is the same: (1 + nominal rate ÷ m)^m − 1, converting the nominal rate at m compounding periods per year into the real annual rate after compounding. They differ only in naming and usage. APY is more common for deposits, savings and investments where you earn interest, emphasising the actual yield you receive; EAR is the more general academic and analytical term used across borrowing, investment analysis and so on, emphasising the true annual rate after compounding. There is also a related but different term, APR (nominal annual rate / annual percentage rate), which is the quote before compounding — do not confuse it with APY/EAR. In short: APY = EAR, both are the real annual rate after compounding; APR is the nominal rate before compounding. The APY output of this calculator can also be read as EAR — the numbers are the same.
Does a higher compounding frequency always mean a higher APY?
Given the same nominal rate, yes — a higher compounding frequency gives a higher APY, because interest is reinvested earlier and compounds more strongly. At a nominal 5%: annual compounding gives 5%, quarterly about 5.0945%, monthly about 5.1162%, daily about 5.1267%. The APY rises as the frequency increases from 1 to 365. Two caveats. First, the rise is diminishing — the jump from annual to monthly is noticeable, but from monthly to daily is tiny, because compounding has a mathematical limit (continuous compounding); the APY ceiling for a nominal 5% is about 5.1271%, and no denser compounding can exceed it by much. Second, this comparison only holds when the nominal rates are the same; in reality different products have different nominal rates, so you must convert everything to APY for a fair comparison. This calculator lets you enter the nominal rate and compounding frequency to get the APY directly, saving manual conversion.
How do Hong Kong banks usually quote deposit rates, and how do I see the real return?
Hong Kong bank deposit and time-deposit advertisements usually show the 'annual rate' (i.e. nominal annual rate / p.a.), which is before compounding and may not reflect what you actually receive. To see the real return, note a few points. First, check the actual tenor: many high-rate promotions are 'special rates' for a shorter term (e.g. 3 or 6 months); the eye-catching annualised rate is for a full year, but if you only hold for a few months the interest is pro-rated, not the full-year amount. Second, check compounding and payout: some products pay all interest at maturity (no compounding), others reinvest periodically, and the APY differs — use this calculator to convert the nominal rate and frequency into APY for a fair comparison. Third, check the conditions: high rates often require 'new funds', a designated account, salary or investment bundling, or a minimum balance; miss them and you may only get the base rate. Fourth, check for fees or FX risk (especially for foreign-currency deposits). In short, do not be lured by the biggest 'high annual rate' in the ad — read the terms, work out the real tenor and post-compounding return, then compare across providers.
Does a higher APY always mean a product is worth investing in?
Not necessarily. APY only reflects one dimension — the annualised return after compounding — and is a good tool for comparing similar products, but 'worth investing' also depends on other key factors. First, risk: higher returns usually come with higher risk. Hong Kong-dollar bank deposits are protected by the Deposit Protection Scheme (with a cap) and carry very low risk, but some products touting ultra-high APYs may be high-risk investments, structured products or even scams where the principal is not guaranteed. Be especially alert when a yield is far above the market norm. Second, liquidity and lock-in: high-rate time deposits usually lock up your funds; early withdrawal may lose interest or even incur penalties, which may not suit you if you need the money soon. Third, conditions and thresholds as noted above. Fourth, inflation: if the APY cannot beat inflation, your real purchasing power still shrinks. Fifth, tax and fees where applicable. So APY is an important benchmark, but evaluate it together with your risk tolerance, time horizon and product terms. This calculator only computes APY and is not investment advice; understand the product's risks and consult a licensed professional if needed.
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References
Content review: Calculatorism Finance Team. Results are for reference only; please refer to the relevant authorities for the official figures.