APR vs APY: The Two Rates That Mean Different Things

You apply for a credit card and the advertised rate is 22% APR. You open a savings account and the advertised rate is 4.25% APY. Two acronyms, both ending in R or Y, both expressing a percentage, both about interest. They are not the same thing. Banks know exactly which one to quote in which context, and almost nobody asks why.

This guide explains the difference, shows the math, and walks through where the gap matters most. The short answer up front: APR is the headline number, APY is the math after compounding is included. Lenders quote APR because it looks lower. Savings accounts quote APY because it looks higher.

The two definitions

APR (Annual Percentage Rate). The annual rate without accounting for intra-year compounding. If a loan charges 1% per month, the APR is 12%. The math just multiplies the periodic rate by the number of periods.

APY (Annual Percentage Yield). The effective annual rate, including compounding inside the year. If interest compounds monthly at 1% per month, you do not earn 12% over the year, you earn 12.68%. The APY is 12.68%.

The relationship between them is:

APY = (1 + APR/n)^n − 1

Where n is the number of compounding periods per year. The more often interest compounds, the larger the gap between APR and APY.

How the gap looks at different rates

Stated APR	Monthly compounding APY	Daily compounding APY
3%	3.04%	3.045%
5%	5.12%	5.13%
10%	10.47%	10.52%
18%	19.56%	19.72%
24%	26.82%	27.11%
30%	34.49%	34.96%

At low rates and infrequent compounding, the difference is rounding error. At high rates and daily compounding (the credit card setup), it is a meaningful slice of your real cost. A 24% APR card is really costing you about 27% per year. That is closer to 30% than to 24%.

You can verify any of these with the compound interest calculator. Set the rate to 24%, set compounding to daily, and look at the implied annual gain. That gain divided by the principal is your APY.

Why lenders quote APR

In the United States, the Truth in Lending Act requires lenders to disclose APR on credit products. The reasoning is that APR is a standardized number you can compare across lenders. If one credit card has 18% APR and another has 22%, the second one really is more expensive, all else equal.

But APR is also the lower of the two numbers. A 22% APR credit card has an effective APY around 24.6%. A 9% APR auto loan with daily compounding has an effective APY around 9.4%. By choosing APR, lenders are quoting the friendlier-looking number while still complying with disclosure law. The math is honest, the framing is intentional.

There is also a more technical version: lenders include fees in APR calculations on certain products (mortgages, for example), which makes APR slightly higher than the pure interest rate. That nuance matters for comparing mortgages but does not change the APR-versus-APY relationship described above.

Why banks quote APY on savings

Same logic, opposite direction. When you deposit money, the bank wants the rate to look as large as possible. A savings account at 4% nominal interest, compounded daily, has an APY around 4.08%. The bank advertises 4.08%, not 4%, because 4.08% is the bigger number.

This is also why high-yield savings accounts at fintechs like Marcus, Ally, or Wealthfront publish APYs as their headline. You see "5.00% APY" and your brain registers a real rate of return. That is exactly the intent.

When you compare savings accounts, compare APY. When you compare loans, compare APR (and check compounding frequency). Different products, different reference points.

Where the gap actually bites

The gap between APR and APY only matters when:

1. The rate is high.
2. Compounding happens frequently inside the year.
3. The balance is large.
4. The time horizon is long.

That describes credit card debt almost perfectly. It describes savings accounts almost not at all.

A specific example. Consider $10,000 carried for a year:

• On a savings account at 4% APR, compounded monthly: you earn $407 in interest. The APR is 4%, the APY is 4.07%. The compounding bought you $7.
• On a credit card at 24% APR, compounded daily: you accrue $2,711 in interest. The APR is 24%, the effective APY is about 27.1%. The compounding cost you $311 beyond the simple 24%.

Same starting balance, same APR gap in absolute terms (~0.07 vs ~3 points). The credit card's compounding is doing real damage. The savings account's compounding is doing real but tiny help.

Mortgages, where APR includes fees

Mortgages are the one product where the APR is meaningfully higher than the note rate, because the APR calculation rolls in closing costs, origination fees, and points.

You might be quoted a 6.5% interest rate on a mortgage and a 6.78% APR. The 6.5% is what your monthly payment is calculated against. The 6.78% is the all-in cost reflecting fees. For comparing mortgage offers, APR is the right number, because it normalizes the impact of fees that vary between lenders.

For estimating your monthly payment, use the lower note rate. For comparing total cost between two mortgage offers, use APR.

Auto loans and the dealer's trick

Car dealerships frequently quote a low APR (3.9%! 1.9%! 0%!) and then make their money elsewhere. The APR is honest. The trick is:

• The promotional rate often applies only to top-tier credit.
• The rate is in exchange for forgoing a manufacturer rebate that might be worth more.
• The rate is on a specific term length (typically 60 months), and you might get a higher total cost than financing through your bank.

A 0% APR for 60 months on a $40,000 car saves you about $4,800 in interest compared to a 5% loan. But if the alternative is a $4,000 manufacturer rebate, taking the rebate and the 5% loan leaves you ahead. The APR comparison alone is not enough.

Credit card cash advances are a separate animal

Most credit cards have a regular purchase APR (let us say 22%) and a cash advance APR (often 28% to 30%). The cash advance APR usually has no grace period, meaning interest accrues from the moment of the transaction.

A $1,000 cash advance at 29% APR with daily compounding, paid off in 30 days, costs about $24 in interest. The same $1,000 in regular purchases, paid before the statement due date, costs nothing.

This is the place where understanding APR and APY directly translates to fewer dollars leaving your wallet. The numbers look similar on paper (29% vs 22%, what is the big deal). The behavioral difference, especially the lack of a grace period on cash advances, is where the actual cost happens.

What to do with all of this

A short checklist:

• Comparing loans, including credit cards. Use APR. Note the compounding frequency. If you carry a balance, mentally inflate the rate by a few points to get to your real cost.
• Comparing savings accounts. Use APY. The difference between 4% and 4.07% is real but tiny on average balances. The difference between 0.01% (a typical big-bank savings rate in 2026) and 4.5% (a typical high-yield savings rate) is enormous and worth your time.
• Comparing mortgages. Use APR for comparison, note rate for payment calculation.
• Reading any rate quote. Ask: is this APR or APY, and how often does interest compound?

The acronyms exist to enable comparison, but the comparison only works when you know what each one actually measures. The next time a credit card offer arrives with "as low as 18.9% APR" in the fine print, mentally translate it to about 20.6% APY and decide if you still want the card.