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Monthly Mortgage Calculator

Monthly Mortgage Calculator

Section titled “Monthly Mortgage Calculator”

Calculate your monthly mortgage payment including principal, interest, property taxes, and insurance for accurate home affordability planning.

%
yrs
mo

Use Cases

Section titled “Use Cases”

This monthly mortgage calculator helps homebuyers determine affordability, existing homeowners plan refinancing, real estate agents provide payment estimates, and lenders qualify borrowers.

What is a Monthly Mortgage Payment?

Section titled “What is a Monthly Mortgage Payment?”

A monthly mortgage payment is the amount paid each month to repay a home loan. It typically includes principal and interest (P&I), and may also include property taxes, homeowners insurance, and PMI.

Monthly Mortgage Payment Formula

Section titled “Monthly Mortgage Payment Formula”

The principal and interest portion is calculated using:

P=r⋅PV1−(1+r)−nP = \frac{r \cdot PV}{1 - (1 + r)^{-n}}

Where:

  • PP = Monthly payment (principal + interest)
  • PVPV = Loan amount (home price minus down payment)
  • rr = Monthly interest rate (annual rate ÷ 12)
  • nn = Total number of monthly payments (years × 12)

Total Monthly Payment:

Total Payment=P+Property Tax+Insurance+PMI\text{Total Payment} = P + \text{Property Tax} + \text{Insurance} + \text{PMI}

Math.js Expression:

home_price = 400000;
down_payment = 80000;
loan_amount = home_price - down_payment;
annual_rate = 0.065;
monthly_rate = annual_rate / 12;
loan_term_years = 30;
num_payments = loan_term_years * 12;


principal_interest = (monthly_rate * loan_amount) / (1 - (1 + monthly_rate)^-num_payments);
property_tax_monthly = 500;
insurance_monthly = 150;
pmi_monthly = 133;


total_monthly_payment = principal_interest + property_tax_monthly + insurance_monthly + pmi_monthly;
total_monthly_payment

Example Calculation

Section titled “Example Calculation”

Home Purchase Details:

  • Home Price: $400,000
  • Down Payment: $80,000 (20%)
  • Loan Amount: $320,000
  • Interest Rate: 6.5% APR
  • Loan Term: 30 years
  • Property Tax: 6,000/year(6,000/year (500/month)
  • Insurance: 1,800/year(1,800/year (150/month)

Calculation:

loan_amount = 320000;
annual_rate = 0.065;
monthly_rate = annual_rate / 12;
num_payments = 30 * 12;


principal_interest = (monthly_rate * loan_amount) / (1 - (1 + monthly_rate)^-num_payments);
principal_interest

Result: 2,022/month (P&I) + 500 (tax) + 150(insurance)=∗∗150 (insurance) = **2,672/month total**

Examples

Section titled “Examples”
  • 250,000loanat6250,000 loan at 6% for 30 years = 1,499/month (P&I only)
  • 350,000loanat6.5350,000 loan at 6.5% for 30 years = 2,212/month (P&I only)
  • 500,000loanat7500,000 loan at 7% for 30 years = 3,327/month (P&I only)
  • 200,000loanat5.5200,000 loan at 5.5% for 15 years = 1,634/month (P&I only)

Common Mistakes & Tips

Section titled “Common Mistakes & Tips”

Only Looking at Principal and Interest: Your actual housing cost includes property taxes, insurance, HOA fees, and maintenance. Budget for the complete monthly expense.

Forgetting About PMI: With less than 20% down, you’ll pay private mortgage insurance until you reach 20% equity, adding 50−50-200+ monthly.

Maxing Out Your Budget: Lenders approve up to 43% debt-to-income, but aim for 28-30% to maintain financial flexibility and handle unexpected expenses.

Not Accounting for Rate Changes: If you’re considering an ARM (adjustable-rate mortgage), understand how payment changes after the fixed period could impact your budget.

Frequently Asked Questions

Section titled “Frequently Asked Questions”

How much house can I afford?

Section titled “How much house can I afford?”

Most experts recommend keeping total monthly housing costs at or below 28-30% of your gross monthly income. Use this calculator to find payment amounts within your budget.

What is included in my monthly mortgage payment?

Section titled “What is included in my monthly mortgage payment?”

Principal (loan repayment), interest (lender’s fee), property taxes, homeowners insurance, and PMI if you put down less than 20%. This is often called PITI.

How does my down payment affect monthly payments?

Section titled “How does my down payment affect monthly payments?”

Larger down payments reduce your loan amount, lowering monthly principal and interest. 20%+ down also eliminates PMI, further reducing monthly costs.

Can my monthly mortgage payment change?

Section titled “Can my monthly mortgage payment change?”

With a fixed-rate mortgage, principal and interest stay constant. However, taxes and insurance can increase over time. ARMs have payment changes after the initial fixed period.

What is a good interest rate for a mortgage?

Section titled “What is a good interest rate for a mortgage?”

Rates vary based on credit score, down payment, loan type, and market conditions. Check current average rates and get quotes from multiple lenders to ensure competitive pricing.

Should I choose a 15-year or 30-year mortgage?

Section titled “Should I choose a 15-year or 30-year mortgage?”

15-year mortgages have higher monthly payments but lower total interest and faster equity building. 30-year mortgages offer lower payments but cost more over time. Choose based on your budget and goals.

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