APR vs Interest Rate: What's the Difference and Why It Matters
When you're shopping for a loan or mortgage, you'll see two rates: the interest rate and the APR (Annual Percentage Rate). They're different numbers, and confusing them can cost you thousands.
The Short Answer
Interest rate = the cost of borrowing the principal, expressed as a percentage per year.
APR = the true annual cost of the loan, including interest and fees, expressed as a percentage.
APR is always higher than or equal to the interest rate. If they're identical, the loan has no fees.
Why APR Exists
Lenders used to advertise low interest rates and then load loans with points, origination fees, broker fees, and closing costs. Borrowers couldn't compare loans fairly. The Truth in Lending Act (TILA) in the US requires lenders to disclose APR so consumers can make apples-to-apples comparisons.
What Goes Into APR
APR typically includes:
- The nominal interest rate
- Origination fees
- Discount points (each point = 1% of the loan)
- Mortgage broker fees
- Closing costs the lender controls
- Mortgage insurance premiums (if required)
APR does not include:
- Title insurance
- Appraisal fees
- Home inspection costs
- Prepaid items (escrow for taxes/insurance)
The Formula
APR = [(fees + total interest) / (principal × loan term in years)] × 100
For mortgages, APR is calculated more precisely using the IRR (Internal Rate of Return) method — finding the rate that makes the present value of all payments equal the net loan amount.
Worked Example
Scenario: $300,000 mortgage, 6.5% interest rate, 30 years, $4,500 in lender fees.
Step 1: Calculate the monthly payment at the stated rate. Monthly rate = 6.5%/12 = 0.5417% Monthly payment = $1,896.20
Step 2: Find the effective loan amount (principal minus fees).
Net loan = $300,000 − $4,500 = $295,500
Step 3: Find the rate that makes $295,500 = PV of 360 payments of $1,896.20.
This requires iteration (Newton-Raphson method), giving:
Monthly APR rate ≈ 0.5593%
Step 4: Annualise. APR = 0.5593% × 12 = 6.71%
The loan advertised at 6.5% actually costs 6.71% per year when fees are included.
When APR Misleads You
APR assumes you hold the loan to full term. For mortgages, most people refinance or sell within 7–10 years — so the true effective cost depends on how long you actually keep the loan.
Example: You're comparing two 30-year mortgages on a $300,000 loan:
| Option | Rate | Points/Fees | APR | Monthly Payment |
|--------|------|-------------|-----|-----------------|
| Loan A | 6.5% | $0 | 6.50% | $1,896 |
| Loan B | 6.0% | $6,000 | 6.25% | $1,799 |
Loan B has a lower APR and lower monthly payment. But you pay $6,000 upfront.
Break-even: $6,000 ÷ ($1,896 − $1,799) = 62 months (5.2 years).
If you sell or refinance before 5.2 years, Loan A was actually cheaper despite the higher APR.
Credit Card APR
For credit cards, APR = the interest rate (no fees are included in the standard calculation). The key differences:
Daily periodic rate = APR ÷ 365. On a card with 22% APR: DPR = 22/365 = 0.0603% per day.
Compounding: Credit cards compound daily in most cases, making the effective annual rate slightly higher than the stated APR.
Effective annual rate at 22% APR compounded daily: (1 + 0.22/365)^365 − 1 = 24.6%
This is why carrying a balance on a 22% APR card actually costs you closer to 24.6% per year.
Mortgage APR vs Interest Rate: Rule of Thumb
- APR significantly higher than rate (0.5%+ difference): high fees — shop around or negotiate
- APR close to rate (0.1% or less difference): low-fee loan — the rate is close to the true cost
- APR equal to rate: no fees at all (rare for mortgages)
Calculate APR
Our APR calculator lets you enter the loan amount, interest rate, fees, and term to compute the true APR — so you can compare loan offers on equal footing.