APR vs EIR: What Card and Loan Rates Really Mean

You see a tidy rate printed on a loan ad or a credit card page and assume that's what borrowing will cost you. Then the actual cost works out higher, and you wonder where the extra came from. The gap usually comes down to two different numbers wearing similar names: the advertised rate and the effective interest rate.

Two numbers, two jobs

When a lender talks about a rate, there are really two figures in play.

The advertised rate — often called the APR, or for some loans a flat rate — is the headline number designed to be simple and eye-catching. It tells you the nominal yearly cost in the cleanest possible terms.

The effective interest rate (EIR) is the number that tells you what borrowing actually costs over a year, once the real mechanics are included. It folds in how interest compounds, how your repayments are timed, and certain fees that the headline rate quietly leaves out.

The two are not enemies. They are answering different questions. The advertised rate answers "what's the sticker price?" The EIR answers "what will this really cost me?" For comparing products, the second question is the one that matters.

Why the EIR comes out higher

If the EIR is the truer figure, why is it almost always higher than the advertised one? A few things are at work, and it helps to take them one at a time.

Compounding. Interest is usually charged more than once a year — monthly, in most cases. When interest is added to your balance and then itself earns interest, the yearly total creeps above the simple headline rate. The more frequently interest is compounded, the wider that gap.

Repayment timing. With many loans you start repaying almost immediately, in regular instalments. But the headline rate, particularly a flat rate, is often calculated as if you had the full amount for the whole tenure. In reality you're paying the loan down over time, so the rate you're effectively paying on the money you actually still owe is higher than it first looks.

Fees folded in. Processing or administrative fees that aren't part of the advertised rate can still be part of what you pay. The EIR is designed to capture more of that real cost, which nudges it up.

None of this is a trick. It's the difference between a marketing-friendly number and an honest one — which is exactly why regulators lean on the honest one.

The flat-rate trap

The clearest place to see the gap is a flat-rate loan, common for car and some personal loans.

With a flat rate, interest is calculated on the original loan amount for the entire tenure. So even after you've paid down half the principal, you're still charged interest as if you owed the full sum. That keeps your monthly interest constant and the headline rate low — but it means the rate you're effectively paying on your shrinking balance is meaningfully higher.

Contrast that with a monthly rest loan, common for home loans, where interest is charged on the outstanding balance. As you pay down the principal, the interest shrinks too. For monthly rest products, the advertised rate and the EIR tend to line up closely, because the headline number already reflects a declining balance.

The takeaway: a low flat rate and a slightly higher monthly-rest rate can cost about the same, or the flat rate can even cost more. Comparing the two headline numbers directly will mislead you. Comparing their EIRs won't.

What this means for credit cards

Credit cards quote an annual interest rate, but the way it compounds — and the fact that interest can apply to new purchases once you carry a balance — means your real cost can sit above the printed figure. This is the same APR-versus-EIR gap, just in card form.

There's a simple way to make the whole question disappear: pay your statement balance in full every month. Do that and no interest is charged at all, so the headline rate and the effective rate are both irrelevant to you. The rate only starts to bite when you carry a balance — which is why we keep returning to the same advice in how to avoid credit card interest and in the mechanics of how credit card interest is calculated. For rewards cards, this matters doubly: any interest you pay will dwarf the cashback or miles you earn, the point we make in air miles vs cashback.

How to compare like for like

When you're weighing two cards or two loans, a few habits keep you honest:

• Compare EIRs, not headline rates. In Singapore, regulated lenders must disclose the EIR, so the number is there if you look. It's the closest thing to an apples-to-apples figure.
• Hold the variables steady. Compare the same loan amount over the same tenure. Change those and the comparison stops being fair.
• Look at the total payable. The single most concrete number is the total amount you'll repay over the life of the loan. It cuts through rate jargon entirely.
• Read the fees. Processing fees, late fees and early-repayment charges can change the real cost in ways no single rate captures.
• Confirm the current figure. Rates move and vary by bank and product, so check your bank's product page or factsheet for the live number rather than trusting an old guide or ad.

The takeaway

The advertised rate is the sticker price; the EIR is what you actually pay. The EIR is higher because it accounts for compounding, repayment timing and fees that the headline number leaves out — and the gap is widest on flat-rate loans, where interest is charged on the original amount the whole way through. When you compare, anchor on the EIR and the total payable, hold the loan amount and tenure constant, and read the fees. And with a credit card, the cleanest move of all is to pay in full each month, so neither rate ever touches you.