Mortgage APR Calculator

What this calculator does

Mortgage offers often place an interest rate beside a slightly higher APR. The interest rate sets the scheduled principal-and-interest payment. APR converts the rate, discount points, and selected prepaid finance charges into one annual borrowing-cost estimate.

Enter the loan amount, note rate, term, points, and other charges that should enter the APR calculation. ToolGrym reports estimated APR, payment, amount financed, scheduled interest, and Total Interest Percentage (TIP).

How mortgage APR is calculated

First, the calculator determines the monthly payment from the full loan amount and note rate:

M = P x r(1 + r)^n / ((1 + r)^n - 1)

It then calculates the amount financed for the APR estimate:

Amount financed = loan amount - discount points - other prepaid finance charges

Finally, it solves for the monthly rate that makes the present value of all scheduled payments equal the amount financed. That monthly rate is multiplied by 12 to estimate APR. The solver uses the actuarial present-value method for a fixed, level-payment mortgage.

Official mortgage APR is governed by Regulation Z. Fee classifications, payment timing, mortgage insurance, odd days, and regulatory tolerances can make a lender disclosure differ from this simplified estimate.

Worked example

Consider a $300,000, 30-year mortgage with a 6.5% interest rate, one discount point, and $2,000 of additional prepaid finance charges:

• Monthly principal and interest: about $1,896.20
• One point: $3,000
• Total entered finance charges: $5,000
• Amount financed for APR math: $295,000
• Estimated APR: about 6.662%
• Scheduled interest over 30 years: about $382,633
• TIP: about 127.5%

The APR is higher than the 6.5% rate because the borrower receives an economic amount of $295,000 for APR purposes while making payments calculated on $300,000.

APR versus points break-even

APR is useful for comparing borrowing cost under a full-term schedule, but it does not answer how quickly points pay back. Use the mortgage points calculator to compare a quoted rate with points against a quoted rate without points. If you expect to sell or refinance early, the break-even result can matter more than a small APR difference.

Use the closing costs calculator to estimate cash to close, then include only the charges that belong in APR here. The mortgage calculator adds taxes, insurance, PMI, and HOA dues to the monthly housing budget.

Common mistakes

1. Entering every closing cost as a finance charge. Appraisal, title, taxes, insurance, and other charges are not automatically included in APR. Follow the official disclosure classification.
2. Comparing loans with different assumptions. Compare offers issued near the same time and verify that loan type, term, lock period, points, and credits match.
3. Using APR as a short-horizon cost. APR generally spreads costs across the scheduled term. An early sale or refinance changes the economic result.
4. Confusing APR with TIP. APR is an annualized rate reflecting selected costs. TIP is total scheduled interest divided by the original loan amount.

Methodology and EEAT review

This calculator uses fixed monthly payments, end-of-month timing, the actuarial present-value method, and a nominal annualized monthly rate. It excludes escrow, property costs, variable rates, irregular payment dates, mortgage-insurance treatment, lender credits, and legal APR tolerance tests. Confirm final figures on the lender’s Loan Estimate and Closing Disclosure. Reviewed July 20, 2026.