Key takeaway: Your credit score is one of the most important factors in mortgage approval and determines both whether you qualify and what interest rate you will pay. A FICO score of 740 or higher typically secures the best conventional mortgage rates, while scores between 620 and 739 still qualify but at higher rates. FHA loans accept scores as low as 580 with a 3.5% down payment, or 500 with 10% down. The difference between a 620 and a 740 credit score can cost you tens of thousands of dollars in extra interest over the life of a 30-year loan.

Why Your Credit Score Matters for a Mortgage

When you apply for a mortgage in the US, lenders use your credit score to assess risk. A higher score tells the lender you have a solid track record of repaying debts on time, which translates to a lower interest rate and better loan terms. A lower score signals higher risk, which means the lender will either charge a higher rate to compensate for that risk or deny the application altogether.

According to the Consumer Financial Protection Bureau, most mortgage lenders use FICO credit scores ranging from 300 to 850 (CFPB, 2026). Conventional loans typically require a minimum score of 620, though Fannie Mae and Freddie Mac have different pricing tiers based on score. FHA loans, backed by the Federal Housing Administration, accept borrowers with scores as low as 580 for a 3.5% down payment or 500 with 10% down.

The fundamentals of credit and lending risk are covered in foundational finance texts such as Principles of Finance, which explains how lenders evaluate creditworthiness alongside income and debt ratios.

How Credit Score Affects Your Rate and Borrowing Power

The credit score tiers used by conventional loan underwriters follow this general pattern:

  • 740 and above: Best available rates and lowest fees. Lenders view you as low-risk.
  • 700 to 739: Slight rate increase, typically 0.125% to 0.25% higher than top-tier rates.
  • 660 to 699: Moderate rate increase, roughly 0.25% to 0.5% above top-tier.
  • 620 to 659: Higher rates and stricter requirements, often 0.5% to 1% or more above top-tier.
  • Below 620: Conventional loans are difficult to secure. FHA or VA loans may be available, but with higher mortgage insurance premiums.

Beyond the rate itself, your credit score affects your debt-to-income ratio (DTI) limits. A borrower with a 780 score may qualify with a DTI up to 50%, while someone with a 640 score might be capped at 43% DTI, limiting how much house they can afford.

As of July 2026, rates change daily and vary by lender, so verify current terms with a licensed loan officer before making decisions. Loan eligibility, limits, and availability also vary by program, lender, and location.

A Worked Example: 620 vs. 740 Credit Score

Consider a borrower applying for a $300,000 30-year fixed-rate conventional mortgage with 10% down ($30,000). The loan amount is $270,000.

Scenario A: Credit score 620

  • Interest rate: 7.5% (hypothetical rate for illustration)
  • Monthly principal and interest: approximately $1,888
  • Total interest paid over 30 years: approximately $409,680

Scenario B: Credit score 740

  • Interest rate: 6.5% (hypothetical rate for illustration)
  • Monthly principal and interest: approximately $1,706
  • Total interest paid over 30 years: approximately $344,160

The difference: $182 per month, or $65,520 over the life of the loan. The borrower with the 740 score also qualifies for a higher loan amount at the same DTI, increasing purchasing power.

Steps to Improve Your Credit Before Applying

Concrete actions you can take in the months before your mortgage application:

Read also: How to Calculate Mortgage Affordability With DTI Ratios in the US

  1. Pay down credit card balances. Credit utilization (the percentage of available credit you are using) heavily influences your score. Aim to keep balances below 30% of your credit limit, ideally under 10%.

  2. Make all payments on time. Payment history is the largest single factor in your FICO score. Set up automatic payments to avoid missed due dates.

  3. Avoid opening new credit accounts. Each new account triggers a hard inquiry, which temporarily lowers your score. New accounts also reduce your average account age.

  4. Dispute errors on your credit report. Request free reports from all three bureaus (Equifax, Experian, TransUnion) at AnnualCreditReport.com. If you find inaccuracies, file disputes immediately.

  5. Keep old accounts open. Closing an account reduces your total available credit and can increase your utilization ratio.

  6. Pay off collections and charge-offs if possible. While paying a collection does not remove it from your report, it shows the debt is resolved, which some lenders view favorably.

Most credit score improvements take 30 to 90 days to reflect in your report, so start early. If you need a faster timeline, consider working with a HUD-approved housing counselor who can guide you through credit repair strategies.

Understanding the Variables

Your mortgage affordability calculator takes into account:

  • Credit score: Determines the interest rate tier you qualify for.
  • Gross monthly income: Your total income before taxes and deductions.
  • Monthly debt payments: Car loans, student loans, credit card minimums, and other recurring obligations.
  • Down payment: The cash you bring to closing, which affects loan-to-value ratio.
  • Property taxes and insurance: Estimated costs that lenders include in your total monthly housing payment.

The calculator uses these inputs to estimate the maximum loan amount you can afford while staying within acceptable DTI limits. A higher credit score improves your rate, which lowers your monthly payment and increases the loan amount you can qualify for at the same income level.

Disclaimer: This article provides educational information about credit scores and mortgage qualification in the United States. It is not personalized financial, lending, or legal advice. Credit score requirements, interest rates, and loan terms vary by lender, program, and location, and rates change daily. Consult a licensed loan officer or HUD-approved housing counselor for guidance specific to your financial situation. For tax-related questions, consult a tax professional.