Personal Loan Amortization Schedule Calculator

This personal loan amortization calculator estimates the fixed monthly payment and total interest for a loan, then the schedule can be built by applying each payment to interest first and principal second. Enter the amount borrowed, APR, and term in years to see the payment and interest estimate; the figures assume equal monthly payments and a fixed rate.

Formula

A standard fixed-payment amortizing loan uses a level monthly payment calculated as:

Payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the starting principal, or amount borrowed, in dollars.
• r is the monthly interest rate as a decimal: APR ÷ 1,200 when APR is entered as a percentage per year.
• n is the number of monthly payments: loan term in years × 12.

The calculator’s total-interest estimate is monthly payment × n − P. The displayed payment is rounded to cents, and the total-interest calculation uses that rounded payment. The schedule itself is a row-by-row account of how those payments reduce principal over time.

Worked Example

Using the calculator’s default inputs: principal P = $20,000, APR 8%, and term 5 years.

1. Convert the annual percentage rate to a monthly decimal: r = 8 ÷ 1,200 = 0.0066666667.
2. Find the number of payments: n = 5 × 12 = 60.
3. Substitute into the payment formula: $20,000 × 0.0066666667 ÷ [1 − (1.0066666667)⁻⁶⁰].
4. The monthly payment is approximately $405.53, rounded to the nearest cent.
5. Total of the rounded payments is $405.53 × 60 = $24,331.80; estimated interest is $24,331.80 − $20,000 = $4,331.80.

Assumptions

• The APR and payment amount remain fixed throughout the term.
• Payments are made monthly, with the first payment one month after the loan begins.
• Interest accrues monthly at APR ÷ 12, expressed as a decimal.
• The estimate excludes fees, taxes, insurance, and other charges because they are not inputs to this calculator.

How a Personal Loan Amortization Schedule Works

For each period, the lender calculates interest on the outstanding balance. The payment covers that period’s interest first; whatever remains reduces principal. For a simplified monthly schedule, interest is approximately beginning balance × monthly rate, principal repaid is payment − interest, and ending balance is beginning balance − principal repaid.

At the start of a fully amortizing loan, the balance is high, so more of a level payment goes to interest. As principal falls, the interest portion generally shrinks and more of the same payment goes to principal. The final payment brings the balance to zero, subject to lender rounding and the exact way interest is accrued.

With the example inputs, first-month interest is about $133.33 ($20,000 × 0.0066666667), leaving about $272.20 of the $405.53 payment to reduce principal. The next month’s interest is calculated on the smaller balance. This is why a payment schedule is more informative than multiplying the original balance by the APR: it shows interest changing as repayment progresses.

Reading and Using the Schedule

A complete schedule usually has one row per payment and columns for payment number or date, beginning balance, payment, interest, principal, and ending balance. To construct a basic estimate, repeat the monthly calculation for each row, using the prior row’s ending balance as the next beginning balance. A lender’s actual schedule may differ slightly because of payment dates, daily interest accrual, rounding, or fees.

• Payment: the amount due for that scheduled period under the assumed level-payment arrangement.
• Interest: the portion charged for borrowing during the period.
• Principal: the portion that reduces the loan balance.
• Ending balance: the unpaid principal after that payment is applied.

The calculator provides a payment and total-interest estimate, not a dated, line-by-line lender statement. To make a detailed schedule, use the actual first due date and lender’s balance, interest method, and payment rules. The schedule is useful for understanding the balance’s progression and checking arithmetic, but it does not establish the amount required to pay off a loan on a particular date.

Common Errors and Limits

• Mixing percent and decimal rates: enter APR as a percentage, such as 8, not 0.08. The formula converts it to a monthly decimal.
• Using years as months: this calculator expects years and multiplies by 12. A five-year term means 60 payments, not five.
• Expecting total interest to be APR × principal × years: that shortcut treats the original principal as if it stayed unchanged. An amortizing balance declines over time.
• Ignoring rounding: a lender may round each period’s interest and adjust the last payment. Small differences from a calculator estimate can accumulate.
• Treating APR as the exact accrual method: the calculator assumes monthly compounding at APR ÷ 12. A contract may calculate interest differently or include charges not modelled here.

Additional principal payments, skipped or late payments, variable rates, payment changes, and fees can alter the schedule. The fixed-payment formula does not model those events. If an extra payment is made, how it is applied matters: reducing principal can change the balance path, while a lender may have particular payment-processing procedures. Check the loan disclosure and servicing information for the contract-specific calculation.

Frequently Asked Questions

What does an amortization schedule show?
It lays out each scheduled payment and separates the amount applied to interest from the amount applied to principal, typically showing the remaining balance after each payment.

How do I calculate a personal loan payment?
Convert APR to a monthly decimal by dividing the percentage rate by 1,200, convert the term to months, and use the fixed-payment formula above. A calculator avoids errors from exponent and rounding calculations.

Does an amortization schedule show the exact payoff amount?
No. A schedule is an estimate based on its assumptions. A payoff figure for a particular date may include accrued interest and contract-specific amounts, so request the exact figure from the lender.

Why does more of my early payment go to interest?
Interest is calculated on the outstanding balance. The balance is largest near the beginning, so the interest portion is larger; as principal is repaid, less interest accrues under the stated assumptions.

Do extra payments change the schedule?
They can, if they are applied to principal. A revised schedule depends on the amount, timing, and lender’s application of the extra payment; this calculator does not model additional payments.

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 | 5 | 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