Understanding how to calculate your mortgage payment is essential for anyone buying a home. This guide breaks down the formula, explains each component, and shows you how to save money on your loan.
The Mortgage Payment Formula
Your monthly mortgage payment consists of four main components, often called PITI:
- Principal - The amount you borrowed
- Interest - The cost of borrowing
- Taxes - Property taxes
- Insurance - Homeowners insurance
Monthly Payment = Principal + Interest + Taxes + Insurance
How to Calculate Principal and Interest
The core of your mortgage payment uses this formula:
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ - 1]
Where:
M = Monthly payment
P = Principal loan amount
r = Monthly interest rate (annual rate ÷ 12)
n = Total number of payments (years × 12)
Where:
M = Monthly payment
P = Principal loan amount
r = Monthly interest rate (annual rate ÷ 12)
n = Total number of payments (years × 12)
Example Calculation
For a $300,000 home with 10% down ($270,000 loan) at 6.5% interest for 30 years:
- P = $270,000
- r = 0.065 ÷ 12 = 0.005417
- n = 30 × 12 = 360
- Monthly payment = $1,706.58
Understanding Amortization
Amortization is how your payment is split between principal and interest over time. Early in your loan, most of your payment goes to interest. As you pay down the principal, more goes toward the loan balance.
Key insight: In the first year of a 30-year mortgage, you might pay $17,000 in interest but only reduce your principal by $4,000!
How to Save Money on Your Mortgage
Use these strategies to reduce your total mortgage cost:
- Make extra payments: Even $100 extra per month can save $50,000+ in interest
- Bi-weekly payments: Pay half your monthly payment every two weeks for one extra payment per year
- Refinance when rates drop: Lowering your rate by 1% can save thousands
- Avoid PMI: Put down 20% to skip private mortgage insurance
- Shorter loan term: A 15-year loan has lower rates and less total interest
Use Our Free Calculators
Try our interactive tools to explore your options:
- Standard Mortgage Calculator - Calculate your monthly payment
- Refinance Calculator - See if refinancing makes sense
- Affordability Calculator - Find out how much house you can afford
- Extra Payments Calculator - See the impact of additional principal