The STJ does not adopt a fixed percentage. It analyzes whether the rate notoriously diverges from the market average, causing exaggerated disadvantage to the consumer (CDC art. 51, IV).
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Identify abusive bank interest by comparing with BACEN market average (CDC art. 51 IV).
A bank loan review action (revisional) challenges interest and charges the consumer considers abusive in credit contracts. The case-law starting point is the STJ: in REsp 1.061.530-RS, the Court held that mere excessive burden does not authorize revision, but kept the analysis of manifest abuse, adopting the Central Bank's market average rate as the benchmark for comparison. When the contract rate diverges significantly from that average, there is an indication of exaggerated disadvantage to the consumer (CDC art. 51, IV), and the excessive charge may be reduced (CC art. 413; Res. CMN 4.557/2017). Case law does not set a single fixed percentage, but often uses the average rate multiplied by 1.5x as a reasonableness benchmark for manifest abuse, without automatically binding any decision. This calculator compares the contractual rate with the BACEN average for the loan type, recomputes the installment with either the Price system (fixed installments) or SAC (constant amortization, declining installments), your choice, using the market rate, and quantifies how much would have been overcharged, also showing the effective annual rate. It is an educational estimate: abuse depends on case-by-case analysis by a specialist attorney.
A bank review action discusses whether the interest charged in a credit contract is abusive. In REsp 1.061.530-RS (a binding repetitive appeal), the STJ held that mere onerousness is not enough: revision requires demonstrated abuse. It adopted the market average rate published by the Central Bank as the main benchmark for comparison, if the contract rate diverges significantly from that average, there is an indication of abuse, in light of CDC art. 51, IV (clauses that place the consumer at an exaggerated disadvantage).
The comparison is always by loan type and period: personal loans, payroll-deductible loans, vehicle financing, revolving credit card, overdraft, and mortgages have very different averages, and the average changes month to month. That is why you must use the BACEN average rate in force on the contract signing date, published at bcb.gov.br/estatisticas/txjuros.
Take an illustrative Price-system loan of R$ 20,000 over 24 installments. At the contractual rate, the installment might be, say, R$ 1,100. The tool recomputes the installment using the entered BACEN average rate for the same debt and term, obtaining, for example, R$ 1,000. The R$ 100 monthly difference is the estimated saving; across the 24 installments, that points to roughly R$ 2,400 overcharged. If the loan is on the SAC system, amortization is constant and the installment declines every month, so the tool shows the first and last revised installments instead of a single figure.
The calculator also estimates the contract's effective monthly rate (from the financed amount, the installment, and the number of installments) and converts it into an effective annual rate, to ease comparison with the market average. These are all comparison figures, not a verdict: the exact amount depends on the contract, the CET disclosure, and the statements.
There are two common limitation periods: revising an ongoing contract usually follows the ten-year period, while recovering overpaid amounts (restitution) observes the 5-year period of art. 206, §5, of the Civil Code. So even paid-off contracts can yield restitution for the last five years, with monetary correction and interest.
To take the case forward, gather the original contract, the statements, the Total Effective Cost (CET), the BACEN rate table for the type and date, and the calculation showing the difference. This tool is an educational estimate: the characterization of abuse is done case by case and must be confirmed by a specialist attorney.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
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src="https://jkit.tools/embed/en-US/abusive-interest-calculator"
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></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
The STJ does not adopt a fixed percentage. It analyzes whether the rate notoriously diverges from the market average, causing exaggerated disadvantage to the consumer (CDC art. 51, IV).
⚠️ Educational estimate. Abuse determination requires case-by-case analysis by a specialist attorney.
Taxa 1.72x a taxa média BACEN, acima do parâmetro de 1,5x usado com frequência pela jurisprudência como indício de abusividade manifesta (STJ REsp 1.061.530 + CDC art. 51, IV). A caracterização final ainda depende de análise caso a caso.
Informe a taxa média BACEN vigente na data de assinatura do contrato (tabela mensal em bcb.gov.br/estatisticas/txcred).
CDC art. 51 IV; CC art. 413; STJ REsp 1.061.530 (taxa média BACEN como parâmetro de abusividade); Res. CMN 4.557/2017.