calculate-loan

01 Loan payments

Personal Loan Payment Calculator and Formula

Calculator No. 01-1339 · Updated · Formula and assumptions shown below

Monthly payment $405.53
Total interest
$4,331.67
= 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 personal loan payment calculator estimates your fixed monthly payment and total interest from the loan amount, annual percentage rate (APR), and term. Enter the figures from a lender’s disclosure to see an arithmetic estimate; the result does not show approval odds or decide whether borrowing is appropriate.

Formula

For a fixed-rate loan with equal monthly payments, the payment is calculated as:

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.
  • n is the number of monthly payments: loan term in years × 12.

Total interest in this calculator is the estimated monthly payment multiplied by the number of payments, minus the amount borrowed: Interest = Payment × n − P. The payment formula shown in the calculator is not rounded internally before the interest calculation; displayed values are rounded to cents. Consequently, a total calculated from the unrounded payment can differ slightly from a total based on making every payment at the displayed cent amount. Actual lender payment schedules and final payments may also reflect rounding.

Worked Example

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

  1. Convert the APR to a monthly decimal rate: r = 8 ÷ 1200 = 0.0066667.
  2. Find the number of monthly payments: n = 5 × 12 = 60.
  3. Substitute into the payment formula: 20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)−60] ≈ $405.53.
  4. Calculate estimated interest using the formula’s unrounded payment: approximately $405.528 × 60 − $20,000 = $4,331.68.

The displayed results are approximately $405.53 per month and $4,331.68 in total interest. Small differences can arise if calculations use the rounded displayed payment at every step rather than the full-precision formula result.

Assumptions

  • The interest rate is fixed throughout the loan term.
  • Payments are equal, made monthly, and begin on a regular schedule.
  • Interest is modelled monthly at APR divided by 12.
  • Fees, taxes, insurance, late charges, optional products, and lender-specific rounding are not included.

When to Use the Estimate

Use the calculator to understand how the amount borrowed, APR, and repayment period affect the basic payment arithmetic. For example, changing the loan amount while holding the APR and term constant shows how the payment changes proportionally. Extending the term generally spreads repayment across more months; because interest accrues over time, the total interest estimate can rise even when the monthly payment falls.

For a useful comparison of figures, enter the same type of loan amount and APR that appear in the lender’s written terms, and use the stated repayment period. If a disclosed rate is variable, a single fixed-rate calculation cannot show how future rate changes might affect payments. A quoted payment may also include fees or other items that this calculator does not model, so check what each figure includes before comparing it.

Reading Results and Common Mistakes

The monthly payment is an estimate of principal and interest under the stated assumptions. Total interest is the amount above the original principal implied by that payment schedule; it is not necessarily every cost associated with borrowing. The calculator cannot tell you whether a lender will approve an application, what terms will be offered, or what payment fits a particular budget.

  • Entering the wrong APR: APR is entered as a percentage per year, such as 8 for 8%, not 0.08. The formula converts it to a monthly rate.
  • Mixing up term units: Enter the duration in years. A five-year loan is entered as 5, not 60; the formula converts years to months.
  • Using the desired amount instead of the amount financed: The principal should match the amount used in the loan calculation. If a lender adds an amount to the balance, the disclosed financed amount may differ from cash received.
  • Treating an estimate as a quote: The calculator leaves out lender-specific charges and payment timing, and rounding can affect the final installment.

Limits and Other Costs

This is a standard amortizing-loan calculation: each scheduled payment covers interest due for the period and reduces principal. It does not model irregular payments, skipped payments, extra principal payments, a changing interest rate, fees added to the balance, or a final payment adjusted by the lender. It also does not calculate an APR from a fee schedule; use the rate disclosed for the specific terms rather than assuming the nominal rate and APR are identical.

To understand the complete cost, review the lender’s written disclosure for the amount financed, payment amount and dates, APR, fees, and total repayment figures. Those documents describe the actual offer and may use details not represented by this simplified formula. This calculator is estimate arithmetic for education, not financial advice; the lender’s disclosure gives the exact figures.

Frequently Asked Questions

How do I calculate a personal loan monthly payment?
Convert the annual APR to a monthly decimal rate by dividing by 1,200, convert the term to months, and apply the fixed-payment formula shown above. This calculator performs those steps for you.

Does APR include personal loan fees?
APR may reflect costs as described in a lender’s disclosure, but this calculator does not separately model fees. Enter the disclosed APR and check the documents for which charges are included in the quoted figures.

Why is total interest higher with a longer loan term?
A longer term means more monthly periods for interest to accrue. The payment may be lower, but the cumulative interest estimate can be higher when the amount and rate are unchanged.

Does the result include origination fees?
No. The calculator uses the entered principal and APR and does not add or subtract fees. Review the lender’s disclosure to see whether a fee is charged or included in the amount financed.

Can I use this for a variable-rate loan?
It can show a simplified estimate if you enter a rate, but it assumes that rate stays fixed for the entire term. It cannot forecast payments after a variable rate changes.

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 | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 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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