This calculator estimates the monthly payment and total interest for a fixed-rate personal loan. Enter the amount borrowed, annual percentage rate (APR), and repayment term to see the scheduled payment and the interest implied by that payment.
Formula
The calculator uses the standard amortizing-loan payment formula. It assumes equal monthly payments, with interest calculated at a fixed monthly rate:
Monthly payment = P × r ÷ [1 − (1 + r)−n]
- P is the amount borrowed, in dollars.
- r is the monthly interest rate, calculated as APR ÷ 1,200. For an 8% APR, r = 0.08 ÷ 12.
- n is the number of monthly payments, calculated as years × 12.
Total interest is estimated as monthly payment × n − P. The calculator displays the payment to the nearest cent, then uses that displayed, rounded payment to estimate total interest. Actual lender calculations can differ because of payment dates, rounding conventions, fees, or a different method of applying interest.
Worked Example
Using the calculator’s defaults—$20,000 borrowed, 8% APR, and five years:
- Convert the APR to a monthly rate: 8 ÷ 1,200 = 0.0066667.
- Calculate the number of payments: 5 × 12 = 60.
- Substitute into the payment formula: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)−60].
- The estimated monthly payment, rounded to cents, is $405.53.
- Using that rounded payment, total interest is $405.53 × 60 − $20,000 = $4,331.80.
This is a mathematical illustration, not a loan offer. The example APR and loan details are inputs for demonstrating the calculation; get the actual amount, APR, payment schedule, and any charges from the lender’s disclosure.
Assumptions
- The interest rate is fixed for the full repayment term.
- Payments are equal, made monthly, and treated as occurring at the end of each monthly period.
- Interest compounds monthly at APR ÷ 12 for this estimate.
- The calculation excludes fees, taxes, insurance, and other charges; none is entered as a separate input.
What Makes Repayment Affordable?
“Affordable” is personal rather than a result the formula can decide. The calculator gives a scheduled payment estimate, but it does not know a borrower’s income, essential expenses, other debt payments, savings needs, or changes in circumstances. A payment that fits one household’s budget may not fit another’s.
To understand how a quoted payment would fit into a budget, compare it with take-home income after accounting for recurring commitments and irregular costs. Consider whether the payment remains manageable if expenses rise or income falls. This is a budgeting exercise, not a prediction of approval or a recommendation to borrow.
The term changes the trade-off shown by the calculation. With the same loan amount and APR, spreading repayment across more months generally lowers the scheduled monthly payment, but it also gives interest more time to accrue. A shorter term generally means larger payments and less time accruing interest. Compare both the monthly amount and the total cost rather than judging by the payment alone.
How to Use and Read the Estimate
- Enter the principal amount being borrowed, not the amount you hope to receive after deductions. If charges are taken out of the proceeds, ask the lender how those charges affect the amount financed.
- Use the APR supplied for the specific offer. Do not substitute a market average or an advertised “from” rate; the rate available to an individual is not determined by this calculator.
- Enter the repayment term in years. The formula converts it to monthly payments, so a five-year term means 60 scheduled payments.
- Read the monthly payment as a principal-and-interest estimate. Read total interest as an estimate over the full scheduled term, assuming payments are made as modelled.
For a real quote, check whether the lender’s stated payment includes every required charge, whether the first payment date affects the amount, and whether the APR or rate can change. The calculator has no fields for origination charges, late charges, optional services, or extra payments, so it cannot incorporate their effects.
Common Problems and Limits
A common misconception is that APR and the interest rate are always interchangeable. APR is a disclosed annualized measure that may account for certain borrowing costs, while the formula here uses APR directly as its annual rate input and divides it by 12. If a lender’s payment calculation uses a different rate convention or includes fees in a different way, the estimate will not reproduce the lender’s exact figures.
Another source of confusion is comparing payments without comparing terms. A smaller payment can result from a longer repayment period, not necessarily from a lower overall cost. Likewise, total interest is not the total amount repaid: in this estimate, scheduled principal plus interest equals the original principal plus the calculated interest, before excluded charges.
The formula is designed for a fixed-rate loan with regular, level payments. It does not model variable rates, skipped or late payments, payment holidays, additional principal payments, or a changing balance caused by fees. If you make extra payments, the payoff date and interest may change, but this calculator does not recalculate them. Treat results as a way to understand the basic arithmetic, not as a substitute for the loan contract or a complete budget assessment.
Frequently Asked Questions
How do I calculate a personal loan payment?
Use the loan amount, monthly rate (APR divided by 1,200), and number of monthly payments in the amortizing-payment formula shown above. The calculator performs those steps and rounds the monthly result to cents.
Does a longer personal loan term lower the payment?
For the same principal and fixed APR, a longer term generally lowers the scheduled monthly payment because repayment is spread across more months. It can increase total interest because the balance is repaid over a longer period.
Does the calculator include loan fees?
No. It uses the entered principal and APR and does not separately model origination charges, late charges, insurance, or other fees. Check the lender’s disclosure for the actual amounts and how they affect proceeds and payments.
Why is my lender’s payment different?
Differences may arise from fees, the amount financed, payment dates, daily rather than monthly interest calculations, rounding, or terms that differ from the inputs. Compare the calculator assumptions with the lender’s written payment schedule.
Is the estimated payment an affordability decision?
No. It is only a repayment calculation. It does not assess income, expenses, approval, or whether a particular payment fits your circumstances.
The result is an estimate; 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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