Important Disclaimer — Not Financial Advice

The results from this calculator are for informational and educational purposes only. They are not a guarantee of actual outcomes and should not be considered financial, investment, tax, or legal advice. Always consult a qualified professional for advice tailored to your specific financial situation. See our Terms of Service and Privacy Policy for more information.

What Is This Calculator?

The QFINHUB mortgage calculator estimates your monthly principal and interest payment for a fixed-rate home loan. I built it because mortgage shopping is one of the few times in life where a 0.25% rate difference is worth $20,000 or more. Three inputs. One payment. Then I show you the total interest, because that's the number most people never see.

📖 Definition

A mortgage calculator estimates the monthly payment, total interest, and amortization schedule for a fixed-rate home loan based on the loan amount, interest rate, and loan term.

Key Takeaways

1

Average 30-year fixed mortgage rate in June 2026 is around 6.85% per FRED.

2

A 0.25% rate difference on a $400,000 loan saves about $70/month or $25,000 over 30 years.

3

Total interest on a 30-year mortgage often exceeds the original loan amount.

4

15-year rates run about 60 basis points below 30-year rates in 2026.

The Formula

M = P [ i(1 + i)^n ] / [ (1 + i)^n - 1 ]

P is the loan principal, i is the monthly interest rate (annual rate divided by 12), n is the total number of monthly payments (360 for a 30-year loan). This is the standard amortization formula used by every U.S. mortgage servicer.

Why This Matters — Real-World Application

FRED data from June 2026 shows the average 30-year fixed mortgage rate sits around 6.85%, down from the 2024 peak of 7.79%. On a $400,000 loan, that 0.94-point drop cuts the monthly payment by about $235 and saves $84,600 over 30 years. If you're still on a 2024 rate and can refi, the math is usually a slam dunk as long as closing costs stay under 2% of the loan balance.

Practical Example

You're buying a $450,000 home with 20% down ($90,000), so your loan amount is $360,000. At 6.85% APR over 30 years, the monthly principal and interest payment is $2,360. Add property taxes (1.2% annually = $450/month), homeowners insurance ($1,500/year = $125/month), and PMI if your down payment is under 20%, and your full PITI payment is around $2,935 to $3,050. Total interest paid over 30 years: $489,600. That's more than the original loan.

Key Factors That Affect Your Results

  • Loan amount (home price minus down payment)
  • Interest rate (APR)
  • Loan term (15, 20, or 30 years most common)
  • Property taxes and homeowners insurance
  • PMI if down payment under 20%

Tips for Using This Calculator

  • 1Get at least three quotes. Mortgage rates can vary 0.25% to 0.50% between lenders on the same day.
  • 2A 15-year loan saves massively in interest. The 2026 rate spread is about 60 basis points, so the payment jump is real but manageable.
  • 3Consider buying points if you plan to stay 7+ years. One point (1% of loan) typically buys 0.25% rate reduction.

Related Calculators

Related Guides & Articles

Sources & References

  • Federal Reserve H.15 Selected Interest Rates (MORTGAGE30US)
  • Freddie Mac Primary Mortgage Market Survey 2026
  • Consumer Financial Protection Bureau mortgage disclosure rules (TRID)

These authoritative sources inform our calculator methodology and ensure accuracy.

QM

Written by Qasem Mohammed

Financial tools developer and founder of QFINHUB. All calculators are built with industry-standard formulas and reviewed for accuracy. Content is for educational purposes only — always consult a qualified financial professional for decisions about your specific situation.

Last updated: July 16, 2026 ·About QFINHUB · Editorial Policy

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QM

Last reviewed by Qasem MohammedJuly 16, 2026

AI & Software Engineer, Founder & Lead Developer at QFINHUB · Editorial Policy