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MoneyBasis

Formulas and assumptions

How MoneyBasis calculates results

Explore the formulas, assumptions and sources behind each estimate. Your inputs provide the starting point; the calculation runs in your browser.

A magnifying glass examining a calculation

Mortgage Calculator

What it estimates

This calculator estimates monthly principal and interest payments for a fixed-rate mortgage using home price, down payment, interest rate and loan term.

How it calculates

M = P × r × (1 + r)^n / ((1 + r)^n − 1)

Monthly mortgage payment uses the standard fixed-rate amortization formula, where P is the loan amount, r is the monthly interest rate, and n is the number of payments.

Inputs

Home price · Down payment · Interest rate · Loan term

Included / not modeled

Included

  • Fixed mortgage rate
  • Entered taxes and insurance
  • Entered PMI, HOA fees and extra payments

Not modeled

  • Variable rates
  • Late payments
  • Selling costs
Assumptions & limitations
  • Taxes, insurance, PMI and HOA fees are included only when you enter them on the Taxes & Fees tab.
  • The rate is treated as a fixed annual percentage, compounded monthly.
  • The schedule assumes every payment is made on time.

Sources

Open Mortgage calculator →