APR vs APY: What's the Difference?

APR and APY are two of the most-confused terms in personal finance — and the confusion is sometimes deliberate, because quoting the more flattering one makes a product look better. Understanding the difference takes about three minutes and helps you compare loans and savings accounts honestly.

The one-line difference

APR (Annual Percentage Rate) is the simple annual rate, before the effect of compounding. APY (Annual Percentage Yield) — also called AER in the UK — is the effective annual rate, after compounding is included. APY is always equal to or higher than the APR it's based on, because it counts the interest you earn on your interest.

Why compounding creates the gap

If interest is only calculated once a year, APR and APY are the same. But most accounts compound more often — monthly, daily — and each time, you start earning interest on the interest already added. APY captures that; APR doesn't.

Take a 12% APR compounded monthly. Each month earns 1%, but because it builds on the prior month's interest, the effective annual yield works out to about 12.68% APY. Same nominal rate, higher real result — purely from compounding frequency.

Why a 5.1% rate can beat a 5.2% rate

This is the trap to watch for. Compounding frequency can flip which number is actually better:

• 5.1% compounded monthly works out to roughly 5.22% APY.
• 5.2% compounded annually is exactly 5.20% APY.

The lower headline rate wins, because it compounds more often. The lesson: never compare two rates without knowing their compounding frequency — convert both to APY (or AER) and compare those.

Which one gets quoted — and why

Here's where it gets a little sneaky, because each side quotes the number that flatters it:

• Savings accounts advertise APY / AER — the higher, compounding-included number — because it looks more generous. That's genuinely what you'll earn, so it's the right one to compare.
• Loans and credit cards advertise APR — the lower, pre-compounding number — because it looks cheaper. But if the loan compounds (credit cards compound monthly or daily), your real cost is closer to the APY equivalent.

So for savings, compare APY to APY. For borrowing, know that the true cost can be a touch higher than the quoted APR once compounding is in.

A note on loan APR

For loans, "APR" carries a second, useful meaning: it's also meant to bundle in mandatory fees, so the APR on a mortgage or personal loan can be higher than the headline interest rate once arrangement fees are spread across the term. That makes APR a better tool than the raw interest rate for comparing loans with different fee structures — just remember it still doesn't capture intra-year compounding.

The practical rules

• Saving? Compare APY (AER) to APY. Higher is better, and it already includes compounding.
• Borrowing? Compare APR to APR (it includes fees), but know your real cost is a little higher once compounding is counted.
• Comparing any two rates? If the compounding frequencies differ, convert both to APY before deciding — a lower nominal rate that compounds more often can win.
• Confused by a quote? Ask for the APY/AER. It's the honest "what will I actually earn or pay" number.

Compounding is the engine behind both APY and long-term investing — for the deeper maths, read compound interest explained. And to choose where your cash should sit, see high-yield savings vs. CDs.