Loan Total Cost Calculator: Payments and Interest

This loan total cost calculator estimates the total of your scheduled monthly payments and the interest paid over the term. Enter the amount borrowed, annual percentage rate (APR), and term to see the monthly payment and total interest; the total cost is the payment multiplied by the number of monthly payments.

Formula

The calculator uses a fixed-payment amortization formula. It first calculates a monthly payment, rounds that payment to cents, then multiplies it by the number of monthly payments:

Monthly payment = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]
Total of payments = monthly payment × n
Total interest = total of payments − P

• P is the amount borrowed, in dollars.
• APR is the annual percentage rate entered as a percent per year.
• r is the monthly rate, calculated as APR ÷ 1,200.
• n is the term in months, calculated as years × 12.

Rounding the payment before calculating the totals reflects the fact that installments are generally expressed in cents. The exact timing and handling of the final payment can differ by contract, so this is an estimate rather than a payoff quote.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed at 8% APR for 5 years:

1. Convert the term to months: 5 × 12 = 60 payments.
2. Convert APR to a monthly rate: 8 ÷ 1,200 = 0.0066667, or about 0.66667% per month.
3. Apply the payment formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] ≈ $405.53 per month, rounded to cents.
4. Multiply the rounded payment by the term: $405.53 × 60 = $24,331.80 total of payments.
5. Subtract the principal: $24,331.80 − $20,000 = $4,331.80 total interest.

These figures assume all 60 payments are made on schedule. A lender’s exact payment schedule may differ slightly because of its calculation conventions, payment dates, or final-payment adjustment.

Assumptions

• The interest rate is fixed for the full term.
• Payments are equal monthly installments, made at the end of each monthly period.
• Interest accrues monthly using APR divided by 12; this is the standard periodic-rate assumption for the calculation.
• The estimate excludes fees, taxes, insurance, PMI, escrow, late charges, and optional add-ons because none are entered as calculator inputs.

What “Total Cost” Means Here

“Total cost” can mean different things in everyday conversation. This calculator labels it as the total of payments: the principal plus modeled interest across the full scheduled term. It is not necessarily the full cash cost of borrowing. Upfront charges, account fees, insurance, taxes, or other costs can raise the amount paid, while discounts or credits can change it. To estimate a broader all-in cost, use the actual charges disclosed for the loan and add them separately where appropriate.

Total interest is shown as a separate figure so the two parts are easy to distinguish. In the example, $20,000 is repayment of the amount borrowed and $4,331.80 is modeled interest. The total payment amount is their sum. A loan with a longer term can have a smaller monthly payment while accumulating more interest, because interest is paid over more months; compare the term and total figures as well as the installment.

How to Use and Interpret the Result

Enter the principal you expect to borrow, not the amount you hope to receive after fees unless that is also the amount on which interest is charged. Enter APR as a percentage number: for example, type 8 for 8%, not 0.08. Enter the repayment length in years. The calculator converts it to months and assumes the same payment and rate throughout.

• For a quote, use the loan amount, APR, and term shown in the lender’s documents.
• If the rate is variable, the payment and interest may change; a fixed-rate estimate cannot model those changes.
• If fees are financed into the principal, include them in the amount borrowed only if they are actually added to the balance.
• When comparing estimates, keep assumptions consistent and check whether quoted totals include fees or other charges.

The output is a mathematical estimate of scheduled payments, not a statement of the amount needed to repay the loan today. A payoff balance at a particular date depends on the payment history, accrued interest, and contract terms.

Common Sources of Differences

Small differences between this estimate and a lender’s figures are possible. The calculator rounds every monthly payment to the nearest cent and assumes a regular monthly schedule. A lender may use daily interest accrual, different payment dates, a slightly adjusted last installment, or fees that are not part of the principal. A disclosed APR can also reflect certain costs differently from the rate used to calculate the periodic payment.

A common misconception is that multiplying the initial loan amount by APR and years gives total interest. That simple multiplication ignores the fact that each payment reduces the principal balance over time. With an amortizing loan, interest is calculated on the outstanding balance, which generally falls as payments are made. The formula accounts for that declining balance under its fixed-rate, regular-payment assumptions.

Do not treat the calculator’s range limits as lending rules. They only define values the tool can process. The lender determines the terms and charges for a specific offer; use the actual disclosure rather than assuming the default example reflects a current quote.

Frequently Asked Questions

What is the total cost of a loan?
Here, it means the sum of the scheduled monthly payments: principal plus estimated interest. It does not automatically include fees, insurance, taxes, or other charges.

Is total cost the same as total interest?
No. Total interest is the borrowing charge modeled by the formula. Total of payments includes both that interest and repayment of the principal.

Why does a longer loan term change the total?
A longer term spreads repayment across more monthly periods. It can reduce the monthly installment, but interest may accumulate for longer, increasing the total paid under otherwise identical assumptions.

Does this calculator include loan fees?
No. It has no fee input. Check the lender’s disclosure for charges, and distinguish fees paid separately from charges added to the loan balance.

Can I use it for a variable-rate loan?
You can calculate an illustrative fixed-rate scenario, but it will not predict future payments if the rate changes. Recalculate using a hypothetical rate to see a separate scenario, not a forecast.

Is this the amount required to pay off my loan?
No. The displayed total assumes every scheduled payment is made over the full term. A payoff quote for a particular date accounts for the remaining balance and accrued interest under the loan contract.

This result is an estimate; the lender’s disclosure gives the exact figures.

Related

• Annual Escrow Analysis Calculator: Estimate the Change
• Average Refinance Cost Calculator and Fee Breakdown
• Amortization Calculator With Escrow Included?

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 cost | Total of payments (loan cost) | $ | pmt * yrs * 12 | 2
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | cost - p | 2