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Mortgage Calculator

Calculate mortgage payments with amortization schedule and LTV ratio.

Mortgage Calculator helps you estimate the monthly payment, total cost, and interest breakdown for a home loan. It uses the standard amortization formula to calculate your fixed monthly payment based on the principal (home price minus down payment), the annual interest rate, and the loan term in years.

Enter the home price, down payment, annual interest rate, and loan term, and the tool instantly shows your estimated monthly payment, total amount paid over the life of the loan, and how much of that is interest. An amortization table shows month-by-month how much of each payment reduces your principal versus goes toward interest.

This calculator is useful for comparing loan options, understanding how a larger down payment reduces your total cost, or evaluating the financial impact of choosing a 15-year versus a 30-year mortgage. Note that actual mortgage payments may also include property tax, homeowner insurance, and PMI depending on your lender.

Frequently Asked Questions

Code Implementation

def calculate_mortgage(home_price, down_payment, annual_rate, years,
                         property_tax_rate=1.2, insurance_annual=1200,
                         pmi_rate=0.5):
    loan = home_price - down_payment
    monthly_rate = annual_rate / 100 / 12
    n = years * 12
    if monthly_rate == 0:
        pi = loan / n
    else:
        pi = loan * (monthly_rate * (1 + monthly_rate) ** n) / ((1 + monthly_rate) ** n - 1)

    tax = home_price * property_tax_rate / 100 / 12
    insurance = insurance_annual / 12
    ltv = loan / home_price * 100
    pmi = (loan * pmi_rate / 100 / 12) if ltv > 80 else 0
    total = pi + tax + insurance + pmi

    print(f"P&I:       ${pi:.2f}")
    print(f"Taxes:     ${tax:.2f}")
    print(f"Insurance: ${insurance:.2f}")
    print(f"PMI:       ${pmi:.2f}")
    print(f"Total:     ${total:.2f}")

calculate_mortgage(400000, 40000, 7.0, 30)

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