Mortgage Calculator Credit Score

Reviewed by: David Chen, CFA | Credit & Mortgage Analyst
Last Updated: October 2025

Your credit score is the single biggest factor determining your mortgage interest rate. Use our mortgage calculator based on credit score to see how different FICO tiers impact your monthly payment and total interest costs.

Credit Score Mortgage Calculator

Total purchase price.
20% down helps avoid PMI.
Select a range to update the Interest Rate below.
Auto-adjusted based on credit score above.
Estimated Monthly Payment
$0.00
Principal & Interest Only

mortgage calculator based on credit score Formula

This calculator uses the standard amortization formula, but the key variable—Interest Rate—is derived from typical Loan-Level Price Adjustments (LLPAs) associated with different credit score tiers.

M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
Source: myFICO Loan Savings Data

Variables

  • M: Monthly Payment.
  • P: Principal Loan Amount (Price – Down Payment).
  • i: Monthly Interest Rate (Rate based on Credit Score / 12).
  • n: Total Number of Payments (Years * 12).

Related Calculators

What is a Mortgage Calculator Based on Credit Score?

A mortgage calculator based on credit score is a specialized tool that acknowledges not all borrowers get the same rate. Lenders use “risk-based pricing,” meaning a borrower with a 760 FICO score will pay significantly less than a borrower with a 640 score.

This tool helps you visualize the “cost of bad credit.” By toggling the credit score dropdown, you can see how improving your score by just one tier could save you thousands of dollars over the life of the loan.

How to Calculate Mortgage with Credit Score (Example)

  1. Home Price: $300,000 with 20% down ($60k). Loan = $240,000.
  2. Scenario A (760 Score): Rate might be 6.5%. Payment = ~$1,517.
  3. Scenario B (640 Score): Rate might jump to 7.5%. Payment = ~$1,678.
  4. Impact: The lower score costs an extra $161/month or nearly $58,000 over 30 years.

Frequently Asked Questions (FAQ)

What credit score is needed for a conventional loan?

Typically, you need a minimum score of 620. However, scores below 700 will result in higher interest rates and higher PMI premiums.

Can I get a mortgage with a 580 credit score?

Yes, FHA loans are often available to borrowers with scores as low as 580 with a 3.5% down payment. Scores between 500-579 may qualify with 10% down.

How much does interest rate change by credit tier?

Generally, interest rates increase by about 0.125% to 0.25% for every 20-point drop in credit score, though this varies by lender and market conditions.

Does a larger down payment help if I have a low score?

Yes. A larger down payment reduces the lender’s risk (Loan-to-Value ratio), which can sometimes offset the negative impact of a lower credit score on your rate.

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