Calculate your monthly mortgage payment, total interest paid, and see a visual breakdown of your home loan costs.
Standard amortization formulaNo sign-up requiredUpdated March 2026
How Mortgage Payments Are Calculated
Monthly mortgage payments are calculated using the standard amortization formula. Each payment covers both interest on the remaining balance and a portion of the principal.
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)
Frequently Asked Questions
Monthly payments use the amortization formula: M = P × [r(1+r)^n] / [(1+r)^n - 1], where P is the loan amount, r is the monthly interest rate, and n is the total number of payments. Early payments are mostly interest; later payments are mostly principal.
Conventional loans typically require 5-20% down. Putting down 20% avoids private mortgage insurance (PMI), which adds 0.5-1% of the loan amount annually. FHA loans allow as little as 3.5% down.
A 15-year mortgage has higher monthly payments but significantly lower total interest. For example, on a $300,000 loan at 6.5%, you'd pay $115,000 in interest over 15 years vs. $382,000 over 30 years.
This calculator shows principal and interest (P&I) only. Your actual monthly payment will also include property taxes, homeowner's insurance, and possibly PMI. A common estimate is to add 25-35% on top of P&I for the full PITI payment.
As of early 2026, average 30-year fixed rates are around 6.5-7%. Rates vary by credit score, loan amount, and down payment. Always shop multiple lenders.