calculate-loan

01 Loan payments

30-Year APR Fixed Loan Payment Calculator

Calculator No. 01-3427 · Updated · Formula and assumptions shown below

Monthly principal-and-interest payment $1,896.20
Total interest
$382,632.00
= Monthly principal-and-interest payment × loan term × 12 − loan amount
Loan amount
$300,000
Input
Interest rate (APR)
6.5 %
Input
You enter
Loan amount ($), Interest rate (APR) (%), Loan term (years)
You get
Monthly principal-and-interest payment ($), Total interest ($)
Rounding
2 dp

Estimate for education, not financial advice. The result follows from the numbers you enter and the formula shown. It is not a quote or an offer, and it does not include fees, taxes or insurance unless the calculator asks for them. Ask your lender for the exact figures.

This calculator estimates the monthly principal-and-interest payment and total interest for a fixed-rate loan repaid over 30 years. Enter the loan amount and annual APR to see the payment schedule’s basic cost; the estimate does not include housing or lender charges.

Formula

The fixed monthly payment is calculated using the standard amortizing-loan formula: M = P × r ÷ [1 − (1 + r)−n]. The calculator rounds the payment to the nearest cent, then calculates total interest as I = M × n − P.

  • P is the starting loan principal, in dollars.
  • APR is the annual percentage rate entered as a percentage.
  • r is the monthly rate as a decimal: APR ÷ 1,200.
  • n is the number of monthly payments: years × 12.
  • M is the monthly principal-and-interest payment, in dollars.
  • I is total interest over the stated term, in dollars.

This is the payment for a level-payment loan: the scheduled payment stays the same, while the portions going to interest and principal change over time. APR is divided by 12 to obtain the monthly rate for this estimate. The result is arithmetic based on the values entered, not a lender quote.

Worked Example

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

  1. Convert APR to a monthly decimal rate: r = 6.5 ÷ 1,200 = 0.0054166667.
  2. Find the number of monthly payments: n = 30 × 12 = 360.
  3. Apply the payment formula: M = 300,000 × 0.0054166667 ÷ [1 − (1.0054166667)−360].
  4. Round the monthly payment to cents: M = $1,896.20.
  5. Calculate total interest using that rounded payment: I = $1,896.20 × 360 − $300,000 = $382,632.00.

The final scheduled payment can differ slightly from the regular payment because actual servicing calculations may use payment dates, daily accrual, or rounding conventions not represented here.

Assumptions

  • The interest rate is fixed for the full modeled term.
  • Payments are made monthly, at the end of each monthly period, with the first payment one month after borrowing.
  • Interest compounds monthly at APR divided by 12.
  • The estimate excludes fees, taxes, insurance, private mortgage insurance (PMI), escrow, and any other charges not entered as calculator inputs.

When to Use This Estimate

Use the calculator to see how a principal amount, APR, and term combine under a standard fixed-payment formula. It can help you examine a quoted loan scenario or compare hypothetical inputs consistently. Enter the principal you want modeled and the APR supplied for the specific loan; do not treat the default APR as a market quote. Get the actual rate, costs, and payment details directly from the lender’s written estimate or disclosure.

The calculator accepts a term in years, while the formula counts monthly payments. A 30-year term therefore means 360 payments. If your contract states a different repayment period, enter that period rather than assuming every fixed-rate loan lasts 30 years. The term input allows values up to 50 years for calculations beyond the common example.

How to Read the Results

The first result is the scheduled monthly principal-and-interest payment. It is not necessarily the total amount due each month on a home loan. Property-related costs, insurance, mortgage insurance, escrow deposits, association charges, or lender fees may add to the amount paid. Because this calculator has no fields for those items, it cannot estimate an all-in monthly housing cost.

Total interest is the sum implied by the rounded monthly payment across all modeled payments, less the original principal. It assumes every payment is made as scheduled and that the loan is not paid off early or changed. A longer term generally spreads repayment across more months, but this calculator only reports the outcome for the exact inputs and formula; it does not account for alternative contract terms or costs.

Common Input Mistakes and Limits

Enter APR as a percentage, such as 6.5 for 6.5%, not as 0.065. The formula itself converts the annual percentage to a monthly decimal. Enter the loan principal in dollars and the term in years. Using months in the years field, or entering a monthly interest rate as APR, changes the result substantially.

APR and the note’s interest rate can be different figures when costs are incorporated in the APR calculation. This simple formula uses the entered APR as its monthly rate and does not separately model financed fees, points, or timing-specific charges. Ask the lender which rate belongs in a payment calculation and review the loan’s disclosed payment schedule.

Rounding matters: the monthly payment is rounded to cents before total interest is calculated, as shown in the example. A lender’s final payment may be adjusted to clear a small remaining balance, and actual accrual can depend on contractual details. The formula does not model late payments, missed payments, extra principal, variable rates, refinancing, or early payoff. The result is an estimate; the lender’s disclosure gives the exact figures.

How to Use This List

Enter the principal amount, APR, and full repayment term shown in the loan information you are evaluating. Check the units before calculating, then use the monthly result as principal and interest only. For a fuller cash-flow picture, separately obtain lender-provided figures for fees, taxes, insurance, and other applicable charges; this calculator does not add them.

Frequently Asked Questions

What does fixed APR mean in this calculation?
The entered annual percentage rate is treated as unchanged throughout the modeled term, with a monthly rate of APR divided by 12.

Does the monthly payment include taxes and insurance?
No. It estimates principal and interest only; taxes, insurance, PMI, escrow, and fees are excluded.

Why is the total interest based on the rounded payment?
The calculator rounds the scheduled payment to cents first, then multiplies that displayed amount by the number of monthly payments for consistency.

Can I use it for a loan with a variable rate?
It can show a hypothetical payment if one APR stayed constant, but it cannot forecast payments when the rate changes.

Is the result a lender quote or approval decision?
No. It is educational estimate arithmetic and does not establish loan terms, eligibility, or approval.

Final Thoughts

A 30-year fixed-loan estimate depends on the principal, APR, and term entered. Use the result to understand the formula, then rely on the lender’s disclosures for contract-specific payment and cost figures.

Related

Formula used
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 principal-and-interest payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2

Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work

Method: the standard loan formula for this calculation, fixed rate and monthly compounding unless stated, rounded as each result states. Not financial advice; no lender, rate or product is recommended. See formulas and assumptions, the disclaimer or report an error.

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