Personal Loan Amortization Schedule Calculator

Use this personal loan amortization calculator to estimate your fixed monthly payment and total interest from the loan amount, annual percentage rate (APR), and term. The outputs summarize the repayment cost; a full month-by-month schedule can be built from those same inputs using the payment and balance formulas below.

Formula

The calculator uses the standard fixed-payment amortization formula. It assumes equal monthly payments and a constant rate across the term:

• Monthly payment: M = P × r ÷ [1 − (1 + r)⁻ⁿ]
• Total interest: I = M × n − P

P is the amount borrowed 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 payment in dollars, and I is the estimated total interest in dollars. The calculator rounds the displayed payment to cents; total interest is then calculated using that rounded payment.

Worked Example

With the default values, P = $20,000, APR = 8%, and the term is 5 years:

1. Convert the APR to a monthly decimal rate: r = 8 ÷ 1,200 = 0.0066667.
2. Convert the term to payments: n = 5 × 12 = 60.
3. Substitute into the payment formula: M = 20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] ≈ $405.53 per month.
4. Estimate total interest using the rounded payment: I = $405.53 × 60 − $20,000 = $4,331.80.

These figures are estimates under the stated assumptions. A lender’s payment schedule may differ because of its exact rate calculation, payment dates, fees, or rounding conventions.

Assumptions

• The interest rate stays fixed for the entire term.
• Payments are made monthly, in equal amounts, with the first payment one month after the loan begins.
• Interest accrues monthly at APR divided by 12.
• Fees, taxes, insurance, and other charges are not included unless represented in the APR or separately entered; this calculator has no separate fee input.

What an Amortization Schedule Shows

An amortization schedule breaks each payment into interest and principal. Early in a fully amortizing loan, the unpaid balance is larger, so more of a payment goes to interest. As the balance falls, the interest portion usually declines and more of each level payment reduces principal. The final scheduled payment brings the balance to zero, subject to lender rounding and timing.

For a particular month, calculate interest as the opening balance multiplied by the monthly rate. Subtract that interest from the payment to find the principal paid. Then subtract principal from the opening balance to find the closing balance. For example, on the first month of the sample loan, estimated interest is $20,000 × 0.0066667, or about $133.33. Of the $405.53 payment, about $272.20 therefore reduces principal, leaving an estimated balance of $19,727.80.

To calculate a later balance directly after k payments, the fixed-rate formula is B_k = P(1 + r)^k − M[(1 + r)^k − 1] ÷ r. Here, B_k is the remaining balance after k monthly payments. A complete schedule applies the monthly interest and principal steps repeatedly; this calculator provides payment and total-interest estimates rather than listing every row.

When to Use the Estimate and How to Read It

A schedule can help explain how a stated loan amount, APR, and term translate into monthly payments, interest over the full term, and a declining balance. It is also useful for checking arithmetic in a quoted repayment plan, provided the inputs and assumptions match the lender’s terms. Enter the principal actually financed, not a desired payment, and use the APR and term supplied in the loan disclosure.

• Monthly payment is the estimated regular amount due under the fixed-payment model.
• Total interest is the payment total minus the original principal. It is not the same as the total amount repaid.
• Total scheduled payments can be estimated as monthly payment × number of months. Add principal to interest to understand the total repayment represented by this calculation.

A longer term generally means more payment periods, so the total interest can increase even when the monthly payment is lower. The comparison is meaningful only if the loan amount, rate assumptions, fees, and payment structure are treated consistently. This is arithmetic, not a prediction of approval or a recommendation about borrowing.

Common Calculation Differences and Limits

APR and the interest rate used to accrue a balance are related disclosures but are not necessarily interchangeable in every lender’s calculation. This simple model treats APR as a nominal annual rate divided evenly across 12 months. The actual contract may use daily accrual, different payment dates, an adjustable rate, or fees included in the disclosed APR but not financed in the balance.

Other differences arise from rounding. The calculator rounds the monthly payment to cents and multiplies that rounded amount by the number of payments for its interest estimate. A lender may carry extra precision internally and adjust the final payment by a few cents. An origination charge paid upfront, a late payment, a skipped or changed payment, or an extra principal payment can also make the real schedule diverge. Extra payments often change the balance path, but their treatment depends on how the servicer applies them; this calculator does not model them.

Check that the term is entered in years, not months, and that APR is entered as a percentage (for example, 8 for 8%), not as 0.08. Do not interpret the estimated total interest as a complete cost figure when charges outside the formula apply. For exact due dates, payoff amounts, fees, and payment allocation, use the lender’s disclosure or account information.

Frequently Asked Questions

What is an amortization schedule for a personal loan?
An amortization schedule is a table showing each planned payment, how much goes to interest and principal, and the balance remaining afterward. It is based on the loan’s amount, rate, term, and payment rules.

How do I calculate the interest portion of a monthly payment?
For this model, multiply the balance at the start of the month by the monthly rate, which is APR divided by 1,200. Subtract that interest from the payment to estimate the amount applied to principal.

Why does more of the payment go to interest at the beginning?
The balance is largest at the start, so applying the monthly rate to it produces a larger interest amount. As principal is repaid, the balance and the interest calculated on it generally decline.

Does this calculator show a full month-by-month schedule?
No. It estimates the fixed monthly payment and total interest. The formulas in this page explain how to generate each schedule row, but the calculator does not display a table of all months.

Does making extra payments change an amortization schedule?
Yes. If an extra amount is applied to principal, the balance can fall faster and subsequent interest calculations may change. The effect depends on payment timing and the lender’s application of extra funds, which this calculator does not model.

Why might my lender’s figures differ?
Differences can come from daily rather than monthly interest accrual, exact payment dates, fees, rate changes, extra or late payments, and rounding rules. The 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