If you can pay $400 a month, how long will your loan last? Most loan tools start with the term and give you a payment. This one works the other way around.
This loan term calculator takes your loan amount, yearly interest rate, and chosen monthly payment. It shows how many months it takes to pay off the loan and how much interest you pay. It suits US borrowers planning a personal loan, car loan, or any fixed-rate debt.
Table of Contents
- What the Loan Term Calculator Shows
- How to Use the Calculator Step by Step
- The Loan Term Formula Behind the Tool
- Worked Example: An $18,000 Personal Loan
- How to Read Each Result
- How Your Payment Changes the Payoff Time
- Limitations and Assumptions
- FAQs About the Loan Term Calculator
What the Loan Term Calculator Shows
The tool needs just three numbers. Results update as you type, so you can test many payments quickly.
- Required Payoff Duration: payoff time in years and in whole months.
- Total Interest Paid: the interest you pay over the full payoff time.
- Total Out-of-Pocket Cost: the loan amount plus all interest.
- Min Interest Only Payment: the first month's interest. Your payment must be higher to make progress.
- Interest % of Payout: the share of your total payments that goes to interest.
- Copy Term Calculation and Reset: copy a text summary, or reload the sample loan.
How to Use the Calculator Step by Step
- Enter the balance in Loan Amount ($). Skip commas and the dollar sign.
- Type the yearly rate in Annual Interest Rate (%). Enter 9.5 for 9.5%.
- Enter the amount you plan to pay in Desired Monthly Payment ($).
- Read the payoff time in the large green box.
- Change the payment up or down to see how the term moves.
The page starts with a sample loan of $20,000 at 7.5%, paid at $450 a month. That loan takes 4.4 years, or 53 months.
The Loan Term Formula Behind the Tool
The tool solves the standard loan payment formula for the number of months. First, it turns your yearly rate into a monthly rate.
-ln(1 - r × P ÷ PMT)÷ln(1 + r)=Months to Pay Off
- P is the loan amount.
- r is the monthly rate: the yearly rate divided by 100, then by 12.
- PMT is your monthly payment.
- ln is the natural logarithm.
The result is often a fraction, such as 55.86 months. The tool rounds months up, since a partial month still needs a payment. Total cost equals the payment times the exact months, and interest equals that cost minus P.
If your payment is not above r times P, the loan never shrinks. The tool then shows "Never (Payment too low)". At a 0% rate, months are simply P divided by PMT.
Worked Example: An $18,000 Personal Loan
Alyssa took out an $18,000 personal loan at 9.5% to remodel her kitchen. She can afford $400 a month and wants to know her payoff date.
| Result | Tool Shows |
|---|
| Required Payoff Duration | 4.7 Years (56 Months) |
| Total Interest Paid | $4,342 |
| Total Out-of-Pocket Cost | $22,342 |
| Min Interest Only Payment | $143 / Mo |
| Interest % of Payout | 19.4% |
Her monthly rate is 9.5 ÷ 100 ÷ 12, about 0.0079. The formula gives 55.86 months, which rounds up to 56. Her final payment will be a bit smaller than $400.
The first month's interest is $142.50, shown as $143. Any payment at or below that never pays off the loan.
How to Read Each Result
- Required Payoff Duration shows whole months, rounded up, and the same count in years to one decimal. A one-month loan reads "1 Month".
- Total Interest Paid is the price of borrowing at your chosen payment. All money results round to whole dollars.
- Total Out-of-Pocket Cost is every dollar you send the lender.
- Min Interest Only Payment is your floor. Paying close to it stretches the loan for many years.
- Interest % of Payout helps you compare loans of different sizes.
Want the reverse view, where you pick the term and get a payment? Use our monthly loan payment calculator instead.
How Your Payment Changes the Payoff Time
Small changes in your payment make a large difference. The table keeps Alyssa's $18,000 loan at 9.5% and changes only the payment.
| Monthly Payment | Payoff Time | Total Interest |
|---|
| $350 | 67 months | $5,205 |
| $400 | 56 months | $4,342 |
| $500 | 43 months | $3,272 |
| $600 | 35 months | $2,632 |
Raising the payment from $400 to $500 saves 13 months and $1,070 in interest. For a mortgage or another loan you already have, our extra payment savings calculator shows a similar effect.
Limitations and Assumptions
- The rate is fixed and compounds monthly. Variable-rate loans and credit cards with new charges will differ.
- Fees, insurance, and late charges are not included.
- There is no amortization schedule, so you cannot see each month's principal and interest.
- Money results round to whole dollars, which hides small differences.
- The tool does not check whether a lender allows your chosen term or payment.
- Inputs have limits. The loan amount must be above $0, the rate 0% to 30%, and the payment at least $10. Anything else shows a message and dashes.
- Total cost uses the payment times the exact fractional months. It can differ by a few dollars from a month-by-month schedule.
FAQs About the Loan Term Calculator
How Do I Calculate How Long It Will Take to Pay Off a Loan?
Enter the balance, the yearly rate, and your monthly payment. The tool solves the loan formula for the number of months.
Why Does It Say "Never (Payment Too Low)"?
Your payment does not cover the monthly interest. The balance would never go down, so raise the payment above the Min Interest Only Payment. If payoff takes over 100 years, the tool shows "Over 100 Years (Payment too low)". The cost cards read "N/A".
Can I Use This for a Car Loan?
Yes, it works for any fixed-rate installment loan. Enter the amount you still owe as the loan amount.
Does Paying More Each Month Really Save Interest?
Yes, a larger payment cuts the balance faster, so less interest builds up. In Alyssa's case, $100 more a month saves $1,070.
Should I Enter the APR or the Interest Rate?
Enter the loan's interest rate for the cleanest estimate. APR also counts fees, so it can slightly overstate the payoff time.
You can explore more borrowing and budgeting tools in our finance and business calculators hub.
This calculator gives planning estimates only and is not financial advice. Reviewed for general accuracy by Prof. Dr. Khalil Mudassar, PhD.