Personal Loan Early Payoff Calculator and Interest Saved

This personal loan early payoff calculator estimates how many monthly payments remain when you pay extra, and how much interest you pay under that schedule. Enter the original loan amount, APR, term, and additional monthly payment; it returns the payoff time and estimated interest paid.

Formula

This calculator uses a standard fixed-rate, level-payment loan formula to calculate the scheduled monthly payment and total interest over the original term. It does not calculate an early payoff: the listed inputs contain no extra-payment amount or payoff date, so its results describe repayment on schedule.

The monthly payment formula is M = P × r ÷ [1 − (1 + r)⁻ⁿ], where M is the monthly payment in dollars, P is the loan principal in dollars, r is the monthly interest rate as a decimal, and n is the number of monthly payments. Convert the entered APR to a monthly rate with r = APR ÷ 1,200, and convert the term to months with n = years × 12.

Total interest is I = M × n − P, where I is interest in dollars. The calculator uses the unrounded payment formula in its total-interest expression; the displayed outputs are rounded to cents. Consequently, a hand calculation using the displayed monthly payment can differ by a small amount from the displayed total.

Worked Example

Using the calculator’s default values—$20,000 principal, 8% APR, and a five-year term—the monthly rate is 8 ÷ 1,200 = 0.0066667, and the term is 5 × 12 = 60 payments.

1. Monthly payment: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = approximately $405.53.
2. Total interest using the formula’s unrounded payment: monthly payment × 60 − $20,000 = approximately $4,331.83.

The payment is rounded to cents for display, while the total-interest expression uses the unrounded formula result. Multiplying the displayed $405.53 by 60 and subtracting $20,000 gives $4,331.80; that three-cent difference is rounding, not an extra charge.

Assumptions

• The APR is fixed for the full term and is entered as an annual percentage.
• Payments are equal monthly payments, made at the end of each monthly period.
• Interest compounds monthly using the entered APR divided by 12.
• The calculation excludes fees, taxes, insurance, and other charges, and assumes no extra payments or changes to the balance.

What an Early Payoff Calculator Should Show

An early payoff calculator normally needs the current balance, interest rate, required payment, extra payment amount or a target payoff date, and sometimes the date of the next payment. It can then model the changing balance period by period. This page’s supplied calculator block does not include those inputs, so it cannot estimate an early payoff date, payment count after extra payments, or interest saved. Its outputs are a baseline for the original scheduled term instead.

That distinction matters because an early payment changes the balance on which later interest is calculated. For a fixed rate and monthly payment, a simplified monthly balance update is new balance = old balance × (1 + r) − payment, with the payment reduced by any amount that goes to fees or other charges. Extra principal paid earlier generally reduces later interest in this mathematical model, but the actual posting and allocation depend on the loan’s terms and servicing.

How to Use the Results

• Loan amount: Enter the principal used to calculate the loan’s scheduled payments. If you are assessing a loan already in progress, its current balance is not interchangeable with the original amount.
• Interest rate: Enter the APR as a percentage, such as 8 for 8%, not 0.08. Obtain the applicable rate and payment details from the lender’s disclosure or account information.
• Loan term: Enter the original term in years. The formula converts it to months, so fractional years represent fractional numbers of monthly periods.
• Monthly payment and interest: Use these as the scheduled-term estimates. They do not account for payment holidays, variable rates, late payments, extra principal, or a payoff quote.

To estimate the effect of paying early, use a calculator that explicitly accepts extra payments or a desired payoff date, and compare its projected interest with the scheduled-term baseline. The comparison is only meaningful when both calculations use the same balance, rate, payment timing, and fee assumptions. For a loan already underway, use the current principal balance and remaining term rather than the original loan figures.

Early-Payoff Details and Common Mistakes

“Paying extra” can mean different things: a recurring additional amount, a one-time principal payment, or paying the entire remaining balance. A model of recurring extra payments should account for each payment date and the final smaller payment; multiplying a regular payment by the number of months may overstate the final amount.

• Confusing APR and monthly rate: The formula divides annual APR by 12 and by 100. Entering 0.08 instead of 8 for an 8% APR changes the result substantially.
• Using the wrong balance: The original principal is appropriate for the original scheduled-term calculation. A payoff estimate during repayment starts with the current balance.
• Assuming every extra dollar reduces principal immediately: Payment allocation, processing dates, and any applicable charges can affect the amount credited to principal. Check the loan documents or ask the servicer how additional payments are handled.
• Rounding too soon: Rounding the monthly payment before calculating every period can create small differences. Actual statements may also use day-based interest or other contract-specific methods.

A payoff amount requested for a particular date may differ from the balance displayed on an account because interest can accrue between the statement date and the payment date, and the contract may specify other amounts due. A general calculator cannot replace a dated payoff quote from the lender.

Frequently Asked Questions

Does this calculator show how much interest I save by paying early?
No. The calculator block has no extra-payment input and calculates interest across the original term. It cannot produce an early-payoff savings figure.

How do I calculate a personal loan’s monthly payment?
Convert APR to a monthly decimal rate by dividing it by 1,200, convert years to months by multiplying by 12, and apply the level-payment formula shown above.

Can I use my current balance instead of the original loan amount?
For a scheduled-payment calculation on a loan already in repayment, the balance and remaining term may be relevant, but this calculator’s term field represents the full input term. It does not model the loan’s past payments or remaining schedule.

Does paying early always reduce interest?
Reducing principal sooner reduces future interest in a basic fixed-rate model. The amount and timing of any real savings depend on payment allocation, contract terms, and charges; the calculator does not assess those details.

Why does my lender’s payoff amount differ from a calculator result?
A calculator may omit interest accrued through the payoff date, fees, payment timing, and contract-specific calculation methods. Request the lender’s payoff figure for the date you intend to pay.

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