A simple mortgage calculator lets you estimate your monthly mortgage payments based on the loan amount, interest rate, loan term, and optionally includes property taxes, homeowners insurance, and mortgage insurance.

How a Simple Mortgage Calculator Works

• Enter the home price and down payment or directly the loan amount.
• Enter the interest rate (annual) and loan term in years.
• The calculator computes your monthly principal and interest payment using the formula:

M=Pr(1+r)n(1+r)n−1M=P\frac{r(1+r)^n}{(1+r)^n-1}M=P(1+r)n−1r(1+r)n​

where

• MMM = monthly payment,
• PPP = loan amount,
• rrr = monthly interest rate (annual rate / 12),
• nnn = total number of monthly payments (loan term in years × 12).

Additional Costs (optional in many calculators)

• Property taxes,
• Homeowners insurance,
• Mortgage insurance (if down payment is less than 20%).

Benefits

• Helps estimate how much house you can afford,
• Compares different loan terms or down payment scenarios,
• Shows effects of extra payments on reducing loan length.

Many free online calculators are available that follow this structure for easy use.