How we calculate
Installments stay equal throughout the contract; part pays interest, the rest reduces the debt.
Formula used
PMT is the installment value, PV is the loan amount, i is the periodic rate, and n is the number of installments.
PMT = PV × i / (1 − (1 + i)⁻ⁿ)
Practical example
A R$ 5,000 loan at 3% monthly over 10 installments results in fixed payments.
How to interpret the result
Compare total paid with the loan amount — the difference is the real cost of credit.
Limitations
Does not include fees, insurance, or taxes that make up the total cost of credit in a real loan.