Mortgage Calculators

Reviewed by: David Chen, CFA.

This calculator is built on standard time value of money (TVM) principles used in financial engineering for accurate mortgage repayment calculations.

Welcome to the ultimate **Mortgage Payment Calculator**. This tool allows you to quickly estimate your monthly principal and interest payment based on the loan amount, interest rate, and term. Understanding this payment is the first critical step in budgeting for a new home or refinancing.

Mortgage Payment Calculator

Estimated Monthly Payment (P&I) $0.00

Mortgage Payment Formula

The standard formula for calculating a fixed-rate monthly mortgage payment (M) is based on the amortization principle.

$$M = P \left[ \frac{r(1+r)^n}{(1+r)^n – 1} \right]$$

Formula Source: Wikipedia – Mortgage Calculator | Investopedia – Mortgage Definition

Variables Explained

Understanding the components is key to using the calculator effectively:

  • Principal Loan Amount (P): The total amount of money borrowed from the lender.
  • Annual Interest Rate (R): The yearly percentage rate charged for borrowing the money. We convert this to a monthly rate (r) for the calculation.
  • Term in Years (N): The length of time over which you agree to repay the loan, typically 15 or 30 years. This is converted to total payments (n).
  • Monthly Payment (M): The resulting payment covering both principal and interest.

Related Calculators

Explore other financial tools to better plan your homeownership journey:

What is a Mortgage Calculator?

A mortgage calculator is an essential financial tool designed to estimate the cost of a mortgage loan. It takes into account the three primary factors—the loan amount, the interest rate, and the repayment term—to determine the required monthly payment for principal and interest (P&I).

This estimation allows potential homeowners to quickly assess affordability, compare different loan products (such as 15-year vs. 30-year mortgages), and plan their monthly budgets accurately. While this calculation provides the P&I payment, users should remember that the total housing cost often includes property taxes, homeowner’s insurance, and sometimes HOA fees, often referred to as PITI.

How to Calculate Mortgage Payment (Example)

Let’s use an example: Principal (P) = $300,000, Annual Rate (R) = 6.0%, Term (N) = 30 years.

  1. Convert Annual Rate to Monthly Rate (r): Divide the annual rate (6.0% or 0.06) by 12. $r = 0.06 / 12 = 0.005$.
  2. Calculate Total Number of Payments (n): Multiply the term in years by 12. $n = 30 \times 12 = 360$ payments.
  3. Calculate the Numerator’s Exponent: Compute (1+r)^n, which is (1 + 0.005)^{360} \approx 6.02257$.
  4. Apply the Formula: M = P \times \frac{r \times (1+r)^n}{(1+r)^n – 1} = \$300,000 \times \frac{0.005 \times 6.02257}{6.02257 – 1} \approx \$1,798.65$.

The estimated monthly payment is $1,798.65.

Frequently Asked Questions (FAQ)

What does P&I mean in my mortgage payment?

P&I stands for Principal and Interest. This portion of your monthly payment goes toward repaying the actual amount borrowed (Principal) and the cost of borrowing that money (Interest).

Does this calculator include property taxes and insurance?

No, this calculator only computes the Principal and Interest (P&I) portion of your payment. It does not include escrow items like Property Taxes, Homeowner’s Insurance, or Private Mortgage Insurance (PMI).

Why does a longer term (e.g., 30 years) cost more interest overall?

A longer term results in lower monthly payments, but because you are paying interest on the outstanding principal for a longer period, the total amount of interest paid over the life of the loan is significantly higher.

What is amortization?

Amortization is the process of gradually paying off a debt over a fixed period through a series of regular payments. In a mortgage, the early payments are heavily weighted towards interest, while later payments prioritize paying down the principal.

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