Two savings accounts both advertise “4.00%.” One compounds interest daily, the other credits it once a year, and after twelve months the first account has paid you more on the same deposit. The number that catches that difference is the annual percentage yield, or APY, and federal law requires banks to quote it precisely so that a 4.07% APY at one bank beats a 4.00% APY at another, full stop, no calculator needed.
APR, the annual percentage rate, is the mirror image: it standardizes the cost of borrowing rather than the reward for saving. The two abbreviations differ by one letter and get mixed up constantly, including by people signing loan papers. Getting them straight is one of the highest-value pieces of financial literacy there is, because these two numbers are the official yardsticks for nearly every deposit account and loan in the country.
APY: the saver’s number
APY answers one question: if you leave your money in this account for a full year, what percentage will it actually earn, counting compounding? Compounding means interest earning interest. An account paying a 4.00% annual rate compounded daily actually yields about 4.08% over a year, because each day’s interest joins the balance and earns its own interest going forward.
The Truth in Savings Act and Regulation DD require banks and credit unions to disclose the APY on deposit accounts, calculated by a uniform federal formula, both in account disclosures and in advertising. That uniformity is the whole point: whatever games an ad might play, the APY is computed the same way everywhere, so comparing two accounts is as simple as comparing two APYs for the same balance and term. Just check the footnotes for minimum balances required to earn the advertised yield and for promotional rates that expire.
APR: the borrower’s number
APR answers the opposite question: what does this loan cost per year, expressed as a percentage of what you borrowed? For closed-end loans like mortgages and auto loans, the APR calculated under the Truth in Lending Act folds in not just the interest rate but also certain required fees, such as points and origination charges on a mortgage. That is why a mortgage’s APR runs higher than its quoted interest rate, and why APR is the better single number for comparing two loan offers with different fee structures.
On credit cards, the picture is simpler: the card’s APR is essentially the yearly expression of the interest rate, and annual fees are not baked into it. Card issuers apply the APR through a daily periodic rate, the APR divided by 365, charged on your balance each day. One consequence worth knowing: because interest accrues daily and is added to what you owe, the true annual cost of carrying a card balance runs slightly higher than the stated APR. And on most cards you can dodge purchase interest entirely by paying the full statement balance by the due date each month.
Why the same account can show both a rate and a yield
Savings products often display an “interest rate” next to a slightly higher “APY.” The rate is the raw annual figure before compounding; the APY includes compounding. Loans run the other way: the “interest rate” is what accrues on your balance, and the “APR” adds required fees on top. A useful habit: on deposits, ignore the rate and read the APY; on loans, ignore the teaser rate and read the APR. In both cases you are reading the legally standardized number instead of the marketing one.
Where the comparisons get sneaky
A few situations deserve extra care. Short-term loans can carry modest-sounding fees that translate into enormous APRs; the CFPB’s example of payday loan APRs shows how a fee of $15 per $100 for two weeks works out to an APR in the neighborhood of 400%. Promotional 0% card offers are real but temporary, and the APR that kicks in afterward is the number that matters if a balance might linger. Variable APRs move with an index, so today’s quote is not a promise. And on the savings side, a sky-high APY on only the first few hundred dollars of a balance is a marketing structure, not a windfall.
The two-line summary worth keeping
APY is what money earns, compounding included; a higher APY is better, and it is the only fair way to compare deposit accounts. APR is what borrowing costs, required fees included on most loans; a lower APR is better, and it is the fair way to compare loan offers of the same type and term. Every bank ad, card agreement, and loan estimate in the country is legally required to hand you these yardsticks. The entire trick is knowing which one to pick up, and reading the footnotes attached to it.
