About this mortgage calculator
A mortgage calculator helps home buyers estimate the monthly principal-and-interest payment before making an offer. It also reveals the true long-term cost of interest across 15-year or 30-year loans.
This tool calculates P&I only. Property taxes, insurance, PMI, and HOA fees (PITI) are additional and vary by location.
How to use
- Enter the home price and planned down payment.
- Enter the expected annual interest rate and loan term.
- Review monthly payment, loan amount, and lifetime interest.
Formula
Payment = P × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1)
P = price − down payment; r = monthly rate; n = months.
Worked examples
Example: $400,000 home, $80,000 down (20%), 6.5% for 30 years → loan $320,000 with a monthly P&I payment around $2,022.
Tips
- 20% down often avoids private mortgage insurance (PMI) in many markets.
- Compare 15-year vs 30-year: higher monthly payment, far less interest.
- A 0.25% rate difference can change total interest by thousands.
Frequently asked questions
Does this include taxes and insurance?
No. It estimates principal and interest only. Add local taxes, insurance, PMI, and HOA for a full monthly housing cost.
Is a 15-year mortgage better?
A 15-year loan usually has a higher payment but much lower total interest. Choose based on cash flow and goals.