A personal loan monthly payment calculator estimates the fixed monthly payment and total interest from the loan amount, annual percentage rate (APR), and term. Enter those three figures to see the payment and an estimated borrowing cost; use the lender’s quoted terms for a more precise comparison.
Formula
The calculator uses the standard fixed-payment amortization formula. It converts the annual APR to a monthly rate, calculates the payment that pays down the balance over the stated number of monthly payments, and estimates total interest by subtracting the original principal from all scheduled payments.
- p = loan principal, in dollars ($).
- apr = annual percentage rate, entered as a percentage (for example, 8 means 8% per year).
- r = monthly interest rate, calculated as apr / 1200.
- n = number of monthly payments, calculated as loan term in years × 12.
- pmt = monthly payment, in dollars ($), rounded to the nearest cent.
- int = estimated total interest, in dollars ($), calculated using the displayed monthly payment for every payment.
In symbols, the unrounded payment is pmt = p × r / [1 − (1 + r)−n]. Here, r = apr / 1200 and n = yrs × 12. The calculator displays the payment rounded to cents; total interest is then pmt × n − p, using that rounded payment. This can produce a small difference from a lender’s final payment schedule, especially if the last payment is adjusted.
Worked Example
Using the calculator’s default values—$20,000 principal, 8% APR, and a five-year term:
- Convert the APR to a monthly rate: 8 / 1200 = 0.0066667, or about 0.66667% per month.
- Find the number of payments: 5 × 12 = 60 months.
- Apply the payment formula: 20,000 × 0.0066667 / [1 − (1 + 0.0066667)−60] = approximately $405.53 per month after rounding to cents.
- Calculate total interest using the displayed payment: $405.53 × 60 − $20,000 = $4,331.80.
The calculator’s results for these defaults are a monthly payment of $405.53 and estimated total interest of $4,331.80. Because the payment is rounded before calculating the total, the result follows the same convention as the calculator.
Assumptions
- The interest rate stays fixed for the entire repayment term.
- Payments are made monthly at regular intervals, with the first payment one month after the loan is issued.
- Interest compounds monthly at APR / 12.
- The estimate does not include origination or other fees, taxes, insurance, optional products, or late charges. Fees that are included in a lender’s APR or financed balance can affect the actual figures.
When to Use the Estimate
Use the calculator to understand how principal, rate, and term shape a scheduled payment. It can help you check a payment quote, estimate the total interest under a fixed-rate schedule, or test how changing one input changes the arithmetic. The result is not an approval decision or a statement about what a borrower can afford.
For a fair estimate, enter the amount you expect to borrow—not necessarily the amount you expect to receive. If a fee is withheld from the proceeds or added to the balance, ask the lender how it is treated and which amount the payment is based on. Enter the APR quoted for the specific loan, rather than substituting a rate found elsewhere. Rates and fees depend on the offer; obtain the applicable figures directly from the lender.
How to Read the Payment and Interest
The monthly payment is the scheduled amount under the formula’s assumptions. Each payment covers interest accrued for that period, with the remainder reducing principal. Early in a fully amortizing loan, a larger share of a payment generally goes to interest because the balance is larger; as the balance declines, the interest portion falls. The payment stays level in this model because the rate and payment schedule stay fixed.
Total interest is the estimated interest paid across all scheduled payments, not the total amount repaid. Add the principal to total interest to get the approximate sum of payments: in the example, $20,000 + $4,331.80 = $24,331.80. This arithmetic does not establish the net amount received if charges are deducted from the loan proceeds.
What Changes the Result—and Common Errors
- Loan amount: With the same rate and term, a larger principal produces a larger payment and more interest in dollars.
- APR: A higher entered APR raises the payment and usually the total interest, all else equal. Make sure the value is a percentage: enter 8 for 8%, not 0.08.
- Term: A longer term usually lowers the scheduled monthly payment but spreads repayment across more months, which can increase total interest. A shorter term generally means larger scheduled payments and fewer periods of interest.
- Rounding: Payment amounts are rounded to cents. A lender may adjust the final payment or use different daily-interest and payment-date conventions, so totals can differ slightly.
- Fees and payment timing: A fee, a delayed first payment, or a payment schedule that is not monthly can change the amount or total cost. This calculator does not model those details.
Do not confuse the monthly payment with the amount of principal repaid each month. The payment includes interest, and the principal portion changes over time. Also, this calculator assumes regular monthly installments; it does not calculate a variable-rate payment, a skipped or late payment, or the effect of extra payments.
Frequently Asked Questions
How do I calculate a personal loan monthly payment?
Convert the APR to a monthly rate by dividing the percentage by 1,200, convert the term to months, then use the fixed-payment formula shown above. The calculator performs those steps and rounds the payment to cents.
Does a longer personal loan term lower the monthly payment?
For the same principal and APR under this fixed-payment formula, extending the term generally lowers the scheduled monthly payment. It also means making more payments, so estimated total interest can be higher.
Does this calculator include loan fees?
No. It uses only the entered principal, APR, and term. Ask the lender whether fees are paid separately, deducted from proceeds, or added to the balance, and use the applicable loan amount and quoted APR when estimating.
Why is my lender’s payment different?
The lender may use a different financed balance, include fees, calculate interest using actual dates, set a different first payment date, or adjust the final payment. Compare the quote’s amount, APR, term, payment frequency, and fee treatment with the calculator inputs.
Is the monthly payment the total cost of a personal loan?
No. It is one scheduled payment. Estimated total interest is shown separately, while fees and other charges are not included here. Review the lender’s disclosure for the complete payment schedule and costs.
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 | $ | 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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