Why does this use a monthly interest rate?

Brazilian lenders almost always quote credit at a monthly rate (taxa ao mês), for example 3.5% a.m., rather than an annual rate. The tool takes that monthly figure directly and also shows the compounded annual equivalent so you can compare it with rates quoted elsewhere.

How is the monthly payment calculated?

It uses the standard Price-table annuity formula: payment = P × r ÷ (1 − (1 + r) raised to the power of minus n), where r is the monthly rate and n the number of months. Every instalment is equal, with interest falling and principal rising over the term.

How is the annual rate worked out?

The annual equivalent compounds the monthly rate twelve times: (1 + monthlyRate) to the power of 12, minus 1. A 3% monthly rate, for instance, compounds to roughly 42.6% a year — much higher than simply multiplying by twelve.

Does this include IOF and fees?

No. The result is the pure interest cost. Brazilian loans also carry IOF tax and sometimes administrative fees, which together make up the CET (custo efetivo total). Ask your lender for the CET to compare offers on a like-for-like basis.

Is the amortisation schedule accurate?

Yes, it follows the Price table month by month, splitting each payment into interest and principal and reducing the balance to exactly zero on the final instalment. Small rounding differences are absorbed in the last payment.

Brazil Personal Loan Calculator

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This Brazil personal loan calculator models a fixed-rate crédito pessoal (or CDC) loan. It takes the monthly interest rate that Brazilian lenders quote, converts it to an annual equivalent, and shows your fixed monthly parcela with a full amortisation schedule.

How it works

Brazilian credit is quoted at a monthly rate (taxa ao mês), so the tool works in months. The fixed payment uses the Price-table annuity formula:

payment = P × r / (1 − (1 + r)^-n)

where P is the amount borrowed, r is the monthly rate as a decimal, and n is the number of months. When r is zero the payment is simply P / n.

The annual equivalent compounds the monthly rate twelve times:

annualRate = (1 + r)^12 − 1

Each month the tool charges interest on the outstanding balance, applies the rest of the payment to principal, and repeats until the balance reaches zero.

Example

Borrow R$10,000 at 3.5% a month over 24 months: the parcela is around R$620, the monthly rate compounds to roughly 51% a year, and total interest runs to several thousand reais. Lowering the rate or shortening the term cuts the interest sharply — try both to see the effect.

Notes

This shows the pure interest cost only. Real Brazilian loans add IOF tax and fees that together form the CET (custo efetivo total) — always compare offers on their CET, not the headline rate.