Unsecured Loan Calculator: Estimate Monthly Payments

An unsecured loan calculator estimates your fixed monthly payment and total interest from the amount borrowed, annual percentage rate (APR), and repayment term. Enter those three figures to see the payment and interest estimate; the calculator does not include lender-specific fees or other charges.

Formula

The calculator uses the standard level-payment formula for a fixed-rate loan that is repaid in equal monthly installments:

Monthly payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the amount borrowed, in dollars.
• r is the monthly interest rate as a decimal: APR ÷ 12 ÷ 100. For example, an 8% APR gives a monthly rate of 0.08 ÷ 12.
• n is the number of monthly payments: loan term in years × 12.

Total interest is calculated as monthly payment × number of payments − amount borrowed. The displayed payment is rounded to cents, and total interest uses that rounded payment. As a result, it reflects the calculator’s regular-payment estimate; a lender’s final installment may differ slightly because of payment dates or rounding conventions.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed, 8% APR, and a five-year term:

1. Convert APR to a monthly decimal rate: 8 ÷ 1200 = 0.0066667.
2. Calculate the number of payments: 5 × 12 = 60.
3. Apply the payment formula: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰] = $405.53 per month, rounded to cents.
4. Calculate total interest using the rounded payment: $405.53 × 60 − $20,000 = $4,331.80.

The estimate is therefore a monthly payment of $405.53 and total interest of $4,331.80 over 60 scheduled payments, assuming the stated terms and regular payments.

Assumptions

• The interest rate is fixed for the entire term.
• Payments are equal, made monthly, and begin on a regular schedule.
• Interest compounds monthly at APR divided by 12.
• The estimate excludes origination or other fees, taxes, insurance, PMI, and escrow. A lender may include fees in the amount financed or calculate charges differently.

What an Unsecured Loan Payment Means

An unsecured loan is not backed by a specific asset pledged as collateral. Personal loans are one common form, though the exact product terms vary. “Unsecured” describes the loan’s collateral arrangement; it does not mean the borrowing is free of obligations or that a payment estimate is a promise of approval.

Each scheduled payment on a standard amortizing loan covers interest accrued since the previous payment and reduces the principal balance. Early in repayment, a larger share of each payment generally goes toward interest; over time, the interest portion falls as the balance is paid down. The payment can remain level while that division changes.

The calculator helps isolate the effect of three inputs. A larger principal generally raises the payment. A higher APR or a shorter term generally raises the monthly payment, while a longer term generally lowers it but may increase the total interest paid. These are mathematical effects under the formula, not a recommendation about borrowing.

How to Use the Estimate

Enter the amount you expect to finance, the APR quoted for the loan, and the repayment term. Use the lender’s actual figures when available: an advertised or preliminary rate may not be the rate used in a final offer, and the amount financed may differ from the cash you receive if fees are added.

• Check whether the APR and term apply to the same proposed loan.
• Compare the monthly payment with the total interest, rather than relying on either number alone.
• For an offer with fees, variable rates, irregular payments, or a different payment schedule, ask for the lender’s payment schedule and use its disclosed figures.
• Use the calculator as an estimate, not as a determination of eligibility, approval, or a personal budget.

APR is entered as a percentage per year, not as a monthly rate. Do not type 0.67 for an 8% APR simply because the monthly rate is about 0.67%; the calculator converts annual APR to a monthly rate itself. The loan term is entered in years, so five years means 60 monthly payments.

Costs and Limits the Calculator Does Not Show

The formula models a fixed-rate, fully amortizing loan with level monthly payments. It does not determine the APR, fees, or amount a lender will offer; these depend on the specific loan terms supplied by the lender. Get the actual rate, payment schedule, and itemized costs directly from the lender’s disclosure.

Fees can affect the total cost even when they do not change the scheduled payment shown here. If charges are paid upfront, they may require cash in addition to loan payments. If they are financed, the amount borrowed may be higher. This calculator has no fee input, so it cannot model either treatment or calculate an APR that includes extra charges.

The result can also differ from a statement when the first payment is not exactly one month after disbursement, dates are irregular, a payment is late or missed, or the lender rounds interest differently. Extra payments and early payoff are not included. A variable rate can change the payment or repayment schedule, while this calculation assumes the APR stays fixed.

Frequently Asked Questions

How much is the monthly payment on a $20,000 unsecured loan?
It depends on the APR and term. With the calculator defaults of 8% APR and five years, the estimated payment is $405.53 per month. Different lender terms produce a different result.

Does a longer loan term lower the payment?
For the same principal and fixed APR, spreading repayment across more months generally lowers each scheduled payment. Because interest accrues for longer, total interest is generally higher. The calculator shows both estimates for the chosen term.

Is APR the same as the monthly interest rate?
No. APR is an annual percentage rate. This calculator converts it to a monthly rate by dividing the percentage by 12 and 100. The lender’s disclosed APR may also account for charges differently from the simple interest calculation used here.

Does this estimate include loan fees?
No. There is no fee input, so the payment and total interest do not include origination or other charges. Check the lender’s itemized disclosure for fees and the total amount financed.

Why does my lender’s payment differ from the calculator?
Possible reasons include a different financed amount or APR, fees, a nonstandard first-payment date, payment timing, rounding, or a variable rate. Compare the calculator inputs with the lender’s stated schedule and ask the lender to explain any difference.

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