30 Year Loan Repayment Calculator: Monthly Payment & Interest

This 30-year loan repayment calculator estimates a fixed monthly principal-and-interest payment and the total interest paid over 360 monthly payments. Enter the loan amount, annual APR, and term in years to see the payment and interest estimate.

Formula

The calculator uses the standard fixed-payment amortization formula. Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ], rounded to cents. Here, P is the amount borrowed in dollars, r is the monthly interest rate as a decimal (APR ÷ 1,200), and n is the number of monthly payments (years × 12). Total interest = rounded monthly payment × n − P. Using the rounded payment for the total makes the displayed arithmetic consistent.

Worked Example

Using the defaults: P = $200,000, APR = 6%, and term = 30 years.

1. Convert the APR to a monthly rate: 6 ÷ 1,200 = 0.005, or 0.5% per month.
2. Convert the term to payments: 30 × 12 = 360 months.
3. Substitute into the payment formula: $200,000 × 0.005 ÷ [1 − (1.005)⁻³⁶⁰] = $1,199.10 per month, rounded to cents.
4. Calculate interest using the displayed payment: $1,199.10 × 360 − $200,000 = $231,676.00.

The estimate is therefore $1,199.10 per month, with $231,676.00 in total interest under these assumptions.

Assumptions

• The interest rate stays fixed for the full loan term.
• Payments are made monthly at the end of each period, with the first payment one month after borrowing.
• Interest compounds monthly at APR ÷ 12.
• The calculation excludes fees, taxes, insurance, PMI, escrow, and any charges not entered as inputs.

What the Results Mean

The monthly payment is a mathematical estimate of principal and interest, not necessarily the full amount collected each month. For a mortgage, taxes, homeowners insurance, mortgage insurance, or escrow payments may add to the bill. The total-interest figure is the sum implied by making the same rounded payment for all 360 months and does not include fees or other costs.

In an amortizing loan, each payment covers the interest due for that period and reduces the remaining principal by the amount left over. Early payments generally contain a larger interest portion because the outstanding balance is higher; later payments reduce principal more quickly. The calculator reports the full-term totals, not a month-by-month schedule.

When to Use the Calculator

Use it to estimate payment arithmetic when you know a proposed loan amount, APR, and term, or to compare hypothetical combinations by changing one input at a time. Enter the principal you expect to borrow, rather than a property price or purchase budget; a down payment changes the amount financed. For the APR and any fees, use figures supplied for the specific loan rather than assuming that an illustrative rate applies to you.

The term field accepts years and converts them to months. A 30-year term means 360 payments under this model. If a loan has a variable rate, irregular payment dates, an interest-only period, a balloon payment, or a different payment frequency, this fixed monthly formula does not reproduce its schedule. Check the loan documents for the actual payment structure.

Common Input and Interpretation Mistakes

Enter APR as a percentage number: type 6 for 6%, not 0.06. The calculator divides by 1,200 to convert the annual percentage to a monthly decimal rate. Enter the amount financed in dollars, and put the term in years rather than months. APR and the interest rate used in a lender’s payment calculation may not be interchangeable when fees or other costs are involved; use the rate specified for the calculation you want to estimate.

Rounding can create small differences from a lender’s schedule, especially if the lender carries fractions of a cent internally, adjusts a final payment, or uses different dates or conventions. This calculator rounds the monthly payment to cents and multiplies that rounded figure by the number of payments to estimate total interest. It also assumes every payment arrives on schedule and the rate does not change.

Limits of the Estimate

This tool calculates level-payment loan arithmetic only. It does not determine eligibility, approval, an offered rate, a property’s total housing cost, or the effect of additional principal payments. It does not model closing costs, prepaid charges, late payments, payment holidays, refinancing, or changes to the balance outside scheduled payments. Obtain the actual APR, payment schedule, and included charges from the lender’s disclosure and loan documents.

This result is an estimate; the lender’s disclosure gives the exact figures.

How to Use This List

This page contains one calculator rather than a list of separate tools. Start with the amount financed, enter the lender’s quoted APR and the term in years, then read the monthly payment and total interest together. Change inputs only to examine clearly labelled hypothetical scenarios, and keep outside costs separate so you do not mistake principal and interest for a complete monthly bill.

Frequently Asked Questions

Does a 30-year loan always have 360 payments?
In this calculator, yes: it assumes one payment each month for 30 years, or 360 payments. A real contract may have different terms or payment timing.

Does the monthly payment include taxes and insurance?
No. It estimates principal and interest only; taxes, insurance, PMI, and escrow are not included.

Why is the total interest based on the rounded payment?
The calculator uses the displayed cents-level payment multiplied by the number of payments, then subtracts the principal. A lender’s exact schedule can differ because of rounding and contract details.

Can I use this for a variable-rate loan?
Only as a fixed-rate illustration for the inputs entered. It cannot model future rate adjustments or their effect on payments.

Where should I get the APR and fees?
Use the figures in the specific lender’s disclosure or loan documents; this calculator does not supply or predict rates or fees.

Final Thoughts

A 30-year repayment estimate is useful for understanding how principal, APR, and term combine in a fixed monthly payment. Treat the result as arithmetic for planning comparisons, and verify the actual schedule and all additional charges in the lender’s disclosure.

Related

• EMI Calculator: How the Monthly Instalment of a Loan Is Calculated
• Loan Calculator With Down Payment: Payment on What You Borrow
• Loan Payment Calculator: Monthly Payment, Total Interest and Cost

in p | Loan amount | $ | 200000 | 1 | 100000000
in apr | Interest rate (APR) | % | 6 | 0.01 | 100
in yrs | Loan term | years | 30 | 0.0833 | 50
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2