Calculate Your Monthly Principal & Interest Payment
Enter your loan details to estimate your monthly mortgage payment (principal and interest only).
| Month | Payment | Principal | Interest | Remaining Balance |
|---|
Sample schedule shows the first 12 months. Estimates do not include taxes, homeowners insurance, HOA fees, or mortgage insurance.
How This Principal and Interest Mortgage Payment Calculator Works
This tool estimates your monthly mortgage payment using the standard fixed-rate loan formula. It focuses strictly on principal and interest so you can clearly understand the core cost of borrowing.
You enter three values:
- Loan amount (the amount you borrow)
- Annual interest rate
- Loan term in years (for example, 15 or 30)
The calculator then returns your estimated monthly payment, total amount paid over the life of the loan, and total interest paid.
The Mortgage Payment Formula
For a fixed-rate mortgage, the monthly principal-and-interest payment is:
M = P × [ r(1 + r)n ] ÷ [ (1 + r)n - 1 ]
- M = monthly principal and interest payment
- P = loan principal
- r = monthly interest rate (annual rate ÷ 12)
- n = total number of monthly payments (years × 12)
If the interest rate is 0%, the payment is simply loan amount divided by number of months.
Why Principal and Interest Matter
Many borrowers look only at a final monthly number from a lender, but breaking the payment into principal and interest gives you better control and better decisions.
Principal Builds Equity
The principal portion reduces your loan balance. Every principal dollar paid increases your ownership stake in the property.
Interest Is the Cost of Borrowing
Interest is what you pay the lender for financing. Early in the loan, a larger share of each payment goes toward interest. Later, more goes to principal.
How Rate and Term Change Your Payment
Interest Rate
Even a small change in rate can significantly affect lifetime interest. A lower rate means a lower monthly payment and less total paid.
Loan Term
A 30-year term typically gives a lower monthly payment than a 15-year term, but usually costs more in total interest over time.
- Shorter term: higher payment, lower total interest
- Longer term: lower payment, higher total interest
Tips to Reduce Total Mortgage Interest
- Improve your credit score before applying for a loan.
- Compare rates across multiple lenders.
- Choose the shortest term you can comfortably afford.
- Make occasional extra principal payments when possible.
- Refinance strategically when rates drop and closing costs make sense.
Important Notes
This calculator estimates only principal and interest. Your full monthly housing payment may also include:
- Property taxes
- Homeowners insurance
- Private mortgage insurance (PMI), if applicable
- HOA dues
Use this as a planning tool, then confirm exact numbers with your lender or mortgage advisor.
Quick FAQ
Is this calculator accurate for fixed-rate loans?
Yes. It uses the standard amortization formula for fixed-rate mortgages.
Does it work for 15-year and 30-year mortgages?
Yes. You can enter any term in years, including 10, 15, 20, or 30.
Does it include taxes and insurance?
No. This tool is specifically for principal and interest only.