Loan Payoff Calculator

How long will it take to pay off your loan at a fixed monthly payment?

Key facts

• The Loan Payoff Calculator needs three numbers: remaining loan balance, annual interest rate (%) and monthly payment, and it starts with 10,000, 6% and 500, which gives 22 months and $562.52 in interest.
• The balance and the payment must each be between 0.01 and 1,000,000,000,000, and the annual rate must be between 0% and 100%.
• The currency selector (USD, EUR, GBP, CAD, AUD, CHF, RUB) only changes how amounts are displayed, and no conversion between currencies happens.
• The result panel lists four values: estimated payoff time in months, starting balance, total interest and total paid.
• The final month charges only the remaining balance plus that month's interest, so the last payment can be smaller than the regular one.
• The calculator shows an error instead of a result if the payment does not exceed the first month's interest or if payoff would take more than 1,200 months (100 years).
• The calculation runs in your browser, and the page's script makes no network requests with the numbers you enter.

How to use

1. Type your current principal into Remaining loan balance, using the figure from your latest statement and not the original loan amount.
2. Type the rate into Annual interest rate (%), for example 12 for 12% a year.
3. Type the part of your payment that goes toward the loan into Monthly payment, then pick a Currency.
4. Click Estimate payoff, then change the payment and click again to compare scenarios. Editing any field clears the previous result.

Formula and rounding

The calculator works in cents. Each month it adds interest, subtracts the payment and starts over until nothing is left.

r        = annual rate (%) / 1200
interest = round(balance × r, to cents)
balance  = balance + interest − min(payment, balance + interest)
months   = number of repeats until balance = 0
total interest = sum of monthly interest
total paid     = starting balance + total interest

Here balance is the amount still owed in currency units, r is the monthly rate as a decimal, and payment is the fixed amount paid each month. At a 0% rate the result is simply the balance divided by the payment, rounded up to whole months.

Worked example: $10,000 at 12%, four payment sizes

Say you owe $10,000 at 12% a year and are deciding between $300 and $600 a month. These are the numbers the calculator returns for each payment.

Monthly payment	Payoff time	Total interest	Total paid
$300	41 months	$2,224.96	$12,224.96
$400	29 months	$1,564.88	$11,564.88
$500	23 months	$1,213.48	$11,213.48
$600	19 months	$994.57	$10,994.57

In the $400 case the first month adds $100.00 in interest, so only $300 of the payment reduces the balance. The second month adds $97.00, and the interest share keeps shrinking as the balance falls.

What an extra $100 a month changes

Going from $400 to $500 a month on that loan ends it 6 months sooner and cuts interest by $351.40. Going to $600 ends it 10 months sooner and saves $570.31.

The comparison assumes your lender applies the extra money to principal and charges no prepayment penalty. Ask before you rely on it.

Why a payment just above the interest drags on for decades

On $10,000 at 12%, the first month's interest is exactly $100.00. A $100 payment is rejected, because the balance would never shrink.

A $101 payment is accepted, and the calculator returns 464 months and $36,847.29 in interest. Nudging the payment up from $101 to $400 turns almost 39 years into 29 months, which is why a small margin over the interest is a warning sign and not a plan.

Mistakes that skew the estimate

• Entering the original loan amount instead of the balance you owe today makes the payoff look longer and costlier than it is.
• Entering a mortgage payment that includes escrow or insurance makes the payoff look shorter than it is, because those parts never reduce principal.
• Entering an APR that bundles in fees does not match how the calculator works, since it applies the rate you type as plain interest on the balance.
• Comparing two loans by averaging their rates hides which one costs more, so run each loan separately.

Payoff estimate versus payoff quote

The calculator projects when a balance would reach zero if nothing changes. A payoff quote from a lender is a different thing: the exact amount needed to close the account on a specific date.

That quote can include interest accrued since your last payment, fees and the lender's posting rules. Use the calculator to plan, and ask the lender when you are ready to close.

What this tool does not do

• The Loan Payoff Calculator does not show a month-by-month amortization table, only the four totals.
• The calculator does not work out a payment for you, so you need to enter the monthly amount yourself.
• The calculator does not model fees, insurance, escrow, penalties, daily interest accrual or day counts between payment dates.
• The calculator does not handle variable rates, one-time lump sums or skipped payments within one run.

Frequently asked questions

Related tools

• Compound Interest Calculator: see the same monthly math working in your favor on savings.
• Savings Goal Calculator: compare paying a loan down faster with saving toward a target.
• Percentage Calculator: check how much of the total paid is interest.

Last reviewed: October 21, 2026