30 Year Loan Payment Calculator: Estimate Monthly Costs

This 30 year loan payment calculator estimates the fixed monthly principal-and-interest payment for a loan repaid over 30 years. Enter the loan amount and annual APR to see the monthly payment and total interest, using a level-payment formula.

Formula

The monthly payment uses the standard amortizing-loan formula: M = P × r ÷ [1 − (1 + r)⁻ⁿ]. Here, M is the monthly payment in dollars, P is the original loan amount in dollars, r is the monthly interest rate as a decimal (APR ÷ 12 ÷ 100), and n is the number of monthly payments (years × 12). Total interest is I = M × n − P, with the monthly payment rounded to cents before calculating the total.

Worked Example

Using the calculator’s defaults: principal P = $300,000, APR = 6.5%, and term = 30 years.

1. Convert APR to a monthly decimal rate: r = 6.5 ÷ 1200 = 0.0054166667.
2. Convert the term to payments: n = 30 × 12 = 360.
3. Substitute: M = 300,000 × 0.0054166667 ÷ [1 − (1.0054166667)⁻³⁶⁰].
4. The unrounded payment is about $1,896.204; rounded to cents, the monthly payment is $1,896.20.
5. Total interest = $1,896.20 × 360 − $300,000 = $382,632.00.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are made monthly at the end of each period, beginning one month after borrowing.
• Interest compounds monthly at APR ÷ 12.
• The estimate excludes fees, taxes, insurance, PMI, and escrow.

How to Use This List

Start with the amount you expect to borrow, not necessarily the property’s purchase price; a down payment or other funds can make those figures different. Enter the APR supplied for the loan scenario you want to estimate, then select 30 years for a standard 30-year schedule. The permitted term field also allows other durations, so the same calculator can illustrate how a shorter or longer term changes payment arithmetic.

Use the monthly payment as principal and interest only. A mortgage bill can include other charges, and this calculator does not estimate them. Ask the lender for the actual APR and a written payment breakdown if you need figures for a specific offer. APR is entered as a percentage, so type 6.5 for 6.5%, not 0.065; the calculator converts it internally.

The interest output is based on the payment rounded to the nearest cent and multiplied by the number of scheduled payments. Actual payment schedules can differ because of lender rounding, payment dates, rate changes, fees, or other contract details. Review the assumptions before treating the output as a comparison or planning figure.

Frequently Asked Questions

What does a 30-year loan payment calculator show?
It estimates the recurring monthly principal-and-interest payment and total interest for a fixed-rate loan with monthly payments.

Does the payment include property taxes or homeowners insurance?
No. Taxes, insurance, PMI, escrow, and lender fees are not inputs here, so add verified figures separately when estimating a full housing payment.

Why can the lender’s payment differ?
The contract may use different payment dates, fees, rounding practices, or rate terms; the displayed APR or borrowed amount may also differ from your inputs.

Does a 30-year term mean exactly 360 payments?
Under this calculator’s assumption of one payment each month, yes: 30 × 12 equals 360 scheduled payments.

Can I use this for a variable-rate loan?
Only as a fixed-rate snapshot. It does not project future rate adjustments or recalculate payments over time.

Why can total interest be greater than the amount borrowed?
Interest accrues across many monthly periods; at the example inputs, the sum of 360 rounded payments exceeds principal by $382,632.

Limits and Common Mistakes

This formula models a fully amortizing loan with equal monthly payments and a constant nominal APR. It does not model an interest-only period, balloon payment, skipped payment, extra principal, refinancing costs, or a changing rate. For a loan with those features, its payment schedule needs additional terms and inputs.

A frequent input error is confusing the loan amount with the home price or entering a percentage in decimal form. Another is reading the result as a complete monthly housing cost; it covers only principal and interest. Rounding every payment to cents also means the calculated lifetime interest is an estimate of scheduled arithmetic, not a lender’s payoff quote. The result is an estimate, and the lender’s disclosure gives the exact figures.

Final Thoughts

A 30-year term spreads repayment across 360 monthly payments, and the calculator makes the principal-and-interest arithmetic visible. Use figures supplied for the specific loan scenario and check the lender’s disclosure for the contract’s actual payment details.

Related

• Deferred Interest Promotion: How It Works
• What Happens When a 0% Balance Transfer Ends?
• Balance Transfer Payoff Calculator: Costs and Timing

in p | Loan amount | $ | 300000 | 1 | 100000000
in apr | Interest rate (APR) | % | 6.5 | 0.01 | 100
in yrs | Loan term | years | 30 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2