Mortgage Calculator
Calculate monthly mortgage payments, total interest paid, and view a detailed amortization schedule.
What is a Mortgage Calculator?
A mortgage calculator lets you estimate the monthly payment, total interest, and full amortization schedule of a home loan before you ever speak to a lender. For most households, a mortgage is the single largest financial commitment they will ever make — spanning decades and easily costing as much in interest as the home itself. Running the numbers on different scenarios is therefore not a luxury but a necessity: changing the rate by even 0.5%, the term by five years, or the down payment by 10% can shift total cost by tens of thousands over the life of the loan.
A good mortgage calculation accounts for more than principal and interest. A typical U.S. or European monthly payment includes property taxes (usually held in an escrow account), homeowner's insurance, HOA or condo fees where applicable, and, when the down payment is below 20%, private mortgage insurance (PMI). Together these are summarized by the acronym PITI — Principal, Interest, Taxes, Insurance — and they are what lenders use to judge affordability, not just the base P&I figure.
Understanding amortization is equally important. In a standard mortgage, early payments are mostly interest and only a small portion reduces principal. This shifts over time so that by the final years, nearly every dollar reduces the balance. Viewing the schedule helps you see exactly when you will cross the 20%-equity threshold that eliminates PMI, understand how refinancing would reset the interest-heavy front of the loan, and decide whether extra principal payments are worthwhile at a given rate.
How is it Calculated?
Monthly P&I uses the same amortization formula as any installment loan:
M = P × [r(1 + r)^n] / [(1 + r)^n − 1]
where P is the loan amount, ris the monthly interest rate (annual ÷ 12), and n is the total number of monthly payments.
Worked example:$300,000 at 6.5% over 30 years. r = 0.065/12 ≈ 0.005417; n = 360. M = 300,000 × [0.005417 × 1.005417^360] / [1.005417^360 − 1] ≈ $1,896.20/month P&I. Total paid ≈ $682,633; total interest ≈ $382,633 — more than the original principal. Add estimated $350/mo taxes and $125/mo insurance and the true PITI payment is closer to $2,371.
Tips for First-Time Home Buyers
- Aim for at least a 20% down payment to avoid PMI and secure better rates.
- Keep housing costs under 28% of gross income; total debt under 36%.
- Shop at least three lenders — rate differences of 0.25% are common.
- Budget 2–5% of the home price for closing costs on top of the down payment.
- Consider a 15- or 20-year term if the higher payment is comfortable — interest savings are huge.
Frequently Asked Questions
What is included in a monthly mortgage payment?
Principal, interest, property taxes, and homeowner's insurance (PITI). PMI and HOA fees may also apply.
How much house can I afford?
The 28/36 rule: spend no more than 28% of gross income on housing, 36% on total debt.
Is a 15-year or 30-year mortgage better?
15-year saves substantial interest but has higher monthly payments. 30-year maximizes cash flow but costs far more in total.
What is PMI and how do I avoid it?
Private Mortgage Insurance protects the lender when you put down less than 20%. Avoid by putting 20% down or refinancing once you reach 20% equity.
Should I make extra principal payments?
Yes, if your rate exceeds your expected after-tax return and you have adequate emergency savings — it shortens the term and cuts interest dramatically.