15-Year Loan Amortization Table and Calculator

A 15-year loan amortization table shows how each of 180 monthly payments is divided between interest and principal, along with the remaining balance. Enter the loan amount and annual APR below to calculate the monthly payment and total interest; the table itself can be built by applying the same monthly calculation to each payment.

Formula

The standard fixed-payment formula calculates a monthly payment that repays the starting balance and its interest over the stated number of months:

Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the original loan principal, in dollars.
• r is the monthly interest rate as a decimal: APR ÷ 1,200. For an 8% APR, r = 0.08 ÷ 12.
• n is the number of monthly payments: years × 12. A 15-year term has 180 payments.

The calculator’s first result is the monthly payment, rounded to cents for display. Its total-interest estimate is monthly payment × number of payments − principal. Because the payment is displayed to cents and the formula assumes that same rounded payment throughout, the result may differ slightly from a lender’s schedule, where a final payment can be adjusted.

Worked Example

Using the calculator’s defaults: principal P = $20,000, APR = 8%, and term = 15 years.

1. Convert the APR to a monthly decimal rate: r = 8 ÷ 1,200 = 0.0066667.
2. Find the number of payments: n = 15 × 12 = 180.
3. Substitute into the payment formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻¹⁸⁰].
4. The monthly payment is approximately $191.13.
5. Using the rounded payment for the total: $191.13 × 180 = $34,403.40 in payments. Subtract the $20,000 principal to estimate $14,403.40 total interest.

Assumptions

• The interest rate is fixed for the full term.
• Payments are monthly, with the first payment one month after the loan begins; regular payments are assumed to arrive on schedule.
• Interest is modelled monthly at APR ÷ 12, with no separate daily-interest adjustment.
• Fees, taxes, insurance, PMI, escrow, late charges, and other costs are not included.

How to Read a 15-Year Amortization Table

A full table has one row per payment period. Common columns are the payment number or date, starting balance, payment amount, interest, principal repaid, and ending balance. For each ordinary month, calculate interest on the balance at the start of that period, subtract that interest from the payment to find principal repaid, and subtract principal repaid from the starting balance.

For the example, first-month interest is about $20,000 × 0.0066667 = $133.33. Of a $191.13 payment, about $57.80 goes to principal, leaving an estimated balance of $19,942.20. In later months, interest is calculated on the smaller balance, so more of the same payment goes to principal. Small differences in the last cents can arise from rounding each month.

To make a table, repeat these steps for all 180 periods. If the last row would leave a small balance or overpay by a few cents, a real servicer may adjust the final payment. A spreadsheet or loan servicer’s schedule can handle exact payment dates and rounding conventions.

What Changes the Payment and Total Interest?

For the same principal and APR, a 15-year term has more monthly payments than a shorter term, but fewer than a longer term. Extending a term generally lowers the formula’s monthly payment while increasing the time interest accrues. Shortening it generally raises the required monthly payment while reducing the number of periods. The exact difference depends on the amount, rate, and payment structure entered; the calculator does not judge whether a payment fits someone’s budget.

• Principal: A larger amount raises the payment and, with other inputs unchanged, increases total interest.
• APR: A different APR changes both the monthly interest calculation and the payment needed to amortize the balance. Enter the rate supplied for the specific loan, not an assumed market rate.
• Term: The number of years determines the count of payments. For 15 years, use 180 months—not 15 payments.
• Extra payments: Additional principal payments can change the payoff schedule, but are not included in this calculator’s fixed-payment result.

Limits and Common Sources of Difference

This is a standard estimate for a fixed-rate loan with equal monthly payments. An adjustable rate, interest-only period, deferred payments, irregular payment dates, or a changing balance requires a different schedule. The calculator also does not determine a loan’s APR from fees; use the APR and payment terms stated in the loan documents, and check how the lender defines and applies them.

Rounding is a frequent source of confusion. The formula produces a mathematical payment, while a lender generally collects amounts in currency units and may round interest for each billing period. The stated payment multiplied by 180 therefore need not match the lender’s final total exactly. A quoted monthly bill may also include costs beyond principal and interest, such as taxes or insurance, which are outside this calculation.

Frequently Asked Questions

How many payments are there on a 15-year loan?
A loan paid monthly for 15 years has 15 × 12 = 180 scheduled payments.

How do I calculate the payment for a 15-year loan?
Convert APR to a monthly decimal by dividing by 1,200, set n to 180, then use P × r ÷ [1 − (1 + r)⁻ⁿ]. This page’s calculator applies that formula.

Does the monthly payment stay the same throughout the loan?
Under the fixed-rate, level-payment assumption, principal and interest together stay approximately level. The interest portion usually declines while the principal portion grows. A lender’s total bill can vary if it includes other charges.

Does a 15-year loan always cost less than a 30-year loan?
Not necessarily in every comparison: the amount, rate, fees, payment structure, and other terms may differ. With the same principal and APR under this calculator’s assumptions, a shorter term has fewer payment periods, but compare actual disclosed terms rather than assuming they match.

Can extra payments change an amortization table?
Yes. If an extra amount is applied to principal, the balance and later interest calculations change. This calculator assumes only the regular scheduled payment and does not model extra payments or any associated loan conditions.

Why might my lender’s table differ?
Possible reasons include payment-date conventions, per-period rounding, fees or other amounts, a rate or payment structure that differs from the assumptions, and an adjusted final payment. Check the lender’s disclosed schedule for loan-specific figures.

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

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 15 | 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