The direct answer
The mortgage interest rate is the contractual rate used to calculate interest, APR is a standardized disclosure measure that incorporates specified finance charges, and points are upfront charges expressed as a percentage of the loan amount that can be associated with a lower rate. They answer different cost questions and should be compared together.
Use the note rate for payment math
Scheduled principal-and-interest calculations use the contractual interest rate, not APR. APR is designed to help compare broader borrowing costs under disclosure rules.
To apply the approach to an editable scenario, use the BRRRR Calculator. For the neighboring question, explore Rental Property Calculator.
Treat points as an upfront-versus-later tradeoff
One point equals 1% of the loan amount, but the amount of rate reduction per point is not fixed across lenders, products or market conditions. Compare actual quoted options.
Compare the same loan structure
APR comparisons are most useful when loan amount, term and product type are comparable. A lower APR does not automatically make a loan best for a borrower who expects to sell or refinance quickly.
Worked example
If a borrower pays $4,000 in points to reduce the monthly payment by $80, the simple cash break-even is 50 months. APR may help compare the broader cost, but the borrower’s expected holding period still matters.
Common mistakes and limitations
Do not substitute APR for the note rate in mortgage-payment calculations or assume one point always buys the same rate reduction.
Refinance eligibility, appraised value, seasoning rules, rates and loan costs are lender-specific and are not predicted by this calculator.
Frequently asked questions
Is APR the rate used to calculate my monthly principal and interest?
No. The contractual interest rate is used for that calculation; APR is a broader disclosure measure.
Does paying one point lower every mortgage by the same amount?
No. The rate reduction depends on the lender, loan product and market pricing.
Sources and further reading
The article’s examples are illustrative arithmetic. The references below provide context for operating, valuation or transaction concepts; they do not endorse the assumptions or the calculator.
- CFPB — What documents should I receive before closing on a mortgage loan?Loan Estimate and Closing Disclosure timing, purpose and borrower review context for covered mortgage transactions.
- CFPB — How should I use lender credits and points (discount points)?Interest-rate, discount-point and lender-credit tradeoffs and disclosure context.
Read our editorial policy for the scope of these educational methods.