sac vs price amortization
The difference between SAC and PRICE is not the contracted interest rate, which is identical in both, but which part of the debt shrinks first: the outstanding balance or the installment.
In the first month PRICE costs R$ 665.86 less than SAC, but that advantage reverses over time: near the end, the SAC installment is already well below the PRICE one.
Shortening the term from 240 to 60 months, the SAC interest saving versus PRICE drops from R$ 68,891.07 to R$ 4,541.70, because there is much less time for the SAC declining balance to offset PRICE compound interest.
The saving does not come from a lower rate, both use 10% per year: it comes only from the amortization shape, which in SAC reduces the outstanding balance faster in the early years.
SAC is generally cheaper in total interest because the outstanding balance decreases faster, reducing the base for monthly interest charges. In PRICE, amortization is small at the start, so interest accumulates for longer. For the same rate and term, that gap shows up in the simulation as the SAC saving, which can reach tens of thousands of reais on long loans.
Because SAC reduces the outstanding balance faster in the early years, and interest is charged on that balance; with less principal outstanding over the life of the loan, less interest accumulates in total, even with the same monthly rate as PRICE.
It depends on cash-flow room in the early years: in the 240-month example, the first SAC installment costs R$ 665.86 more per month than PRICE, an amount that needs to fit the budget before counting on the interest savings down the road.
Yes, but by a smaller margin: over 60 months, the interest gap between both systems drops to R$ 4,541.70, against R$ 68,891.07 over 240 months, because the SAC advantage compounds with contract length.
⚠️ Educational simulation. Real estate financing may include insurance (MIP, DFI), administration fees and TR/IPCA correction not included here.
SAC saves R$ 197.434,91 in total interest.
Resolution CMN 3.121/2003 (amortization systems). Rate entered by user, not provided by the tool.
Outstanding balance
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