calculate-loan

01 Loan payments

Total Cost of a Loan Calculator: Payments and Interest

Calculator No. 01-6285 · Updated · Formula and assumptions shown below

Monthly payment $405.53
Total interest
$4,331.80
= Monthly payment × loan term × 12 − loan amount
Loan amount
$20,000
Input
Interest rate (APR)
8 %
Input
You enter
Loan amount ($), Interest rate (APR) (%), Loan term (years)
You get
Monthly payment ($), Total interest ($)
Rounding
2 dp

Estimate for education, not financial advice. The result follows from the numbers you enter and the formula shown. It is not a quote or an offer, and it does not include fees, taxes or insurance unless the calculator asks for them. Ask your lender for the exact figures.

A total cost of a loan calculator estimates the amount you will repay by combining the loan principal with interest paid over the term. Enter the loan amount, annual percentage rate (APR), and term to see the monthly payment and total interest; adding those results gives the estimated total of scheduled payments.

Formula

The calculator uses the standard amortizing-loan payment formula. It assumes equal monthly payments and a fixed APR:

  • Monthly payment: M = round[P × r ÷ (1 − (1 + r)−n), 2]
  • Total paid: M × n
  • Total interest: (M × n) − P

P is the amount borrowed in dollars, r is the monthly interest rate expressed as a decimal (APR ÷ 1,200), n is the number of monthly payments (years × 12), and M is the monthly payment in dollars, rounded to the nearest cent. The calculator displays total interest; adding it to P gives the total scheduled payments.

Worked Example

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

  1. Convert the APR to a monthly rate: 8 ÷ 1,200 = 0.0066667.
  2. Convert the term to payments: 5 × 12 = 60 months.
  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 number of payments: $405.53 × 60 = $24,331.80 total scheduled payments.
  5. Subtract principal: $24,331.80 − $20,000 = $4,331.80 in estimated interest.

The displayed headline is the monthly payment, and the second result is total interest. Together with the original principal, they show the estimated scheduled repayment total.

Assumptions

  • The interest rate stays fixed throughout the loan term.
  • Payments are equal, made monthly, and begin one month after the loan is issued.
  • Interest accrues monthly at APR divided by 12, with no separate daily-interest adjustment.
  • Fees, taxes, insurance, PMI, escrow, late charges, and optional extra payments are not included.

How to Use the Estimate

Use the loan amount that will actually be financed, rather than a purchase price that includes a down payment or costs paid separately. Enter the APR and term supplied for the specific loan offer or disclosure. The default figures are only a worked example; they are not a statement about current or typical loan rates. If a lender quotes a different rate or term, enter those figures to produce a corresponding estimate.

The monthly payment helps show the scheduled installment under the model. Total interest estimates the financing cost across all scheduled payments, while total paid includes both principal and interest. A longer term often means more payments and can increase total interest when the rate and principal are unchanged, even if the monthly payment is lower. The result is arithmetic, not a measure of whether a particular payment fits a person’s budget or whether a lender will approve an application.

What “Total Cost” Includes—and Leaves Out

“Total cost of a loan” can refer to different amounts. This calculator defines it narrowly as principal plus interest paid through equal monthly installments. It does not calculate every amount that might appear in a loan transaction. A lender’s fees, financed charges, insurance, taxes, or other required payments can change the amount paid overall. Some charges may be paid at closing or at another time rather than included in monthly installments.

For a fuller comparison, identify which amounts are included in each loan’s quoted APR and payment, and review the lender’s itemized disclosure. Do not add a charge twice if it is already included in the amount financed or payment. Entering an APR alone cannot reconstruct specific fees or determine how a lender applies them.

Common Calculation Issues and Limits

  • Confusing APR with a monthly rate: Enter an annual APR such as 8, not 0.08 or 0.0067. The calculator converts the annual percentage to a monthly rate internally.
  • Using years as months: The term field is in years. A five-year term becomes 60 monthly payments.
  • Expecting exact lender figures: The payment is rounded to cents. A lender may use different rounding, payment dates, or accrual methods, so the final amount can differ slightly.
  • Assuming the rate never changes: The formula models a fixed rate. It does not model a variable rate, a temporary introductory rate, irregular payments, or a changing payment schedule.
  • Treating interest as every cost: Interest is not the same as fees or other loan-related expenses. Those require separate figures and are not calculated here.

This formula is intended for a fully amortizing loan: scheduled payments cover interest and reduce principal until the balance is repaid at the end of the term. It is not designed for interest-only periods, balloon payments, revolving credit balances, or loans with unusual payment structures. For those, the lender’s payment schedule is needed for an exact estimate.

Frequently Asked Questions

How do I calculate the total cost of a loan?
For this calculator’s definition, multiply the monthly payment rounded to cents by the number of payments. That total includes principal and interest. Subtract the amount borrowed to find estimated interest.

Is total loan cost the same as total interest?
No. Total interest is the amount paid for borrowing under the modeled schedule. Total scheduled payments include the principal repaid as well as interest. Other charges may also apply but are outside this calculation.

Why is the calculator’s answer different from my lender’s quote?
The calculator assumes a fixed APR, equal monthly payments, monthly rate conversion, and cent-rounded installments. A quote may include fees, different payment timing, variable rates, or other terms. Check the lender’s itemized figures for the exact schedule.

Does a longer loan term reduce the total cost?
A longer term usually spreads repayment across more installments, but under the same principal and rate it can increase total interest. The precise payment and interest depend on the figures entered and the loan’s actual terms.

Does the calculator include loan fees?
No. It calculates scheduled principal and interest only. Use the lender’s disclosure to identify fees and other charges and understand whether any are financed or paid separately.

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

Related

Formula used
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 | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2

Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work

Method: the standard loan formula for this calculation, fixed rate and monthly compounding unless stated, rounded as each result states. Not financial advice; no lender, rate or product is recommended. See formulas and assumptions, the disclaimer or report an error.

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