Personal Loan Calculator — Monthly Payment & Total Interest
Enter the loan amount, annual interest rate, term and payment frequency to instantly see your instalment amount, total interest paid and a chart showing your balance falling to zero.
%
months
Payment frequency
Fixed instalment required to fully repay the loan
17,746.78
Total repaidPrincipal
84.5%
Total interest
15.5%
- 1
Periodic interest rate
8.5% ÷ 100 ÷ 12 = 0.007083 - 2
Number of payments
48 - 3
Growth factor
(1 + 0.007083)ⁿ = 1.4033How much one unit grows over the full term at the periodic rate. - 4
Payment per period
15,000 × 0.007083 × 1.4033 ÷ (1.4033 − 1) = 369.72
How does this calculator work?
Monthly payment = P × r(1+r)^n / [(1+r)^n − 1], where r is the monthly rate and n is the number of payments. For a $15 000 loan at 8.5 % over 48 months, the payment is about $371 and total interest roughly $2 820. Use the donut chart to see how interest stacks up against principal.
Formula
How this is calculated
A personal loan is amortised: each payment covers first the interest on the remaining balance and then reduces the principal. The standard amortisation formula M = P × r(1+r)^n / [(1+r)^n − 1] determines the fixed periodic payment M that will reduce the balance to exactly zero after n payments, where r is the rate per period (annual rate ÷ periods per year) and P is the principal.
For bi-weekly or weekly frequencies, the annual rate is divided by 26 or 52 respectively, and the term in months is converted to the equivalent number of shorter periods. More frequent payments slightly reduce total interest because the balance is reduced faster.
The donut chart shows the split between principal and interest inside the total amount repaid — for a typical 8 % personal loan over 4 years, roughly 18 % of every payment goes toward interest. The balance curve shows how the outstanding debt falls slowly at first (when interest dominates each payment) and then steepens as principal repayment accelerates.
Frequently asked questions
The formula M = P × r(1+r)^n / [(1+r)^n − 1] is derived by solving for the constant payment that makes the present value of all future payments equal to the loan principal at the given rate. This keeps your repayment predictable and ensures the loan is exactly repaid after n periods.
Yes, modestly. Bi-weekly payments mean 26 half-payments per year (≈13 full monthly payments instead of 12), which reduces the balance faster and cuts total interest. The effect is most pronounced on longer loans at higher rates.
For a $15 000 loan over 4 years, the difference between 5 % and 12 % APR is about $50 per month and over $2 400 in total interest — so comparing lenders is worth the effort. Use the calculator to test different rates side by side.
Also known as
TG we-Calculate Editorial Team. (2026). Personal Loan Calculator — Monthly Payment & Total Interest [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/personal-loan-calculator
TG we-Calculate Editorial Team. "Personal Loan Calculator — Monthly Payment & Total Interest." TG we-Calculate. 2026. https://we-calculate.com/calculator/personal-loan-calculator.
TG we-Calculate Editorial Team, "Personal Loan Calculator — Monthly Payment & Total Interest," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/personal-loan-calculator
@misc{wecalculate_personal_loan_calculator, title = {Personal Loan Calculator — Monthly Payment & Total Interest}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/personal-loan-calculator}}, year = {2026}, note = {TG we-Calculate} }
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