Total de Juros Pago

Total interest paid on a loan

Add up every installment you pay, subtract the principal you borrowed, and what's left is the total interest: total_interest = Σ PMT − PV. Under the Price system every PMT is identical, which collapses the math to n·PMT − PV. Under SAC the installments shrink from one month to the next, and you end up paying less interest overall since the balance comes down faster.

Take R$ 100,000 at 1% per month over 100 months. Price gets you to roughly R$ 58,700 in interest; SAC lands around R$ 50,500. That R$ 8,200 gap is what a flat installment costs you, the price tag on the convenience of paying the same amount every month. If you want an honest comparison between offers, look at the CET (Custo Efetivo Total). It rolls in fees, IOF and insurance instead of stopping at the headline rate.

Real-world applications

This is the number behind everyday money decisions: budgeting, weighing Price against SAC, picking a term (stretch it out and the installment drops, but the interest bill balloons), running the numbers on a refinance, or deciding whether to throw extra cash at the balance. On a mortgage, trimming even 12 months off the term through amortizações extras can save you tens of thousands of reais in interest.

FAQ

Why does Price always pay more interest than SAC? The outstanding balance drops more slowly under Price, so interest keeps piling up on a bigger number for longer.

Does total interest equal the CET cost? No. Total interest covers only the interest itself. CET goes further and adds IOF, registration fees, opening fees and mandatory insurance, all expressed as an annual rate.

Is a longer term always worse? You'll always pay more interest in total, but the monthly bite is lighter. When cash is tight, a longer term paired with voluntary amortizações can be a fair compromise.