Calculadora de Renda Fixa
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
VF = VI × (1 + taxa)^(DU/252)
About this calculator
The Fixed Income Calculator allows you to project the future value of a fixed income investment using an annual interest rate based on business days, following the standard of 252 business days per year. Simply enter the initial amount, the annual rate in percentage, and the number of business days in the period. The tool applies the formula FV = PV × (1 + rate)^(BD/252), where PV is the present value, rate is the annual rate in decimal, and BD is business days.
This calculator is ideal for investors who want to simulate the return on securities such as CDBs, LCIs, LCAs, and debentures, which often use compound capitalization based on business days. For example, investing R$ 10,000 in a CDB paying 100% of the CDI (currently 13.65% per year) for 63 business days, the calculator shows the gross amount before income tax.
Remember that the result shown is the gross value, without deducting taxes or fees. For long-term investments, income tax is applied on a regressive basis according to the current table (22.5% up to 180 days, 20% from 181 to 360 days, 17.5% from 361 to 720 days, and 15% over 720 days). Use the calculator as a planning tool, but always consider the tax impact and custody fees, if any.
The calculator assumes that the entered rate is annual and already net of taxes (if you want the net value, manually deduct the income tax). The number of business days must be a positive integer. For periods in calendar days, use the standard compound interest calculator. This tool is useful for comparing different fixed income investments with the same business day base.
Frequently asked questions
What does 'base 252' mean?
Base 252 considers that a year has 252 business days, ignoring weekends and holidays. It is the standard used in the Brazilian financial market for fixed income securities.
Does the result already include income tax?
No. The calculated value is gross. You must deduct income tax according to the regressive table: 22.5% for up to 180 days, 20% from 181 to 360 days, 17.5% from 361 to 720 days, and 15% over 720 days.
Can I use this calculator for investments in calendar days?
No, it is specific to business days. If your investment uses calendar days, use the standard compound interest calculator.
How do I convert an annual rate to the 252 basis?
The rate should be entered as annual. The formula automatically converts it by raising to the power BD/252.
What is the difference between this calculator and the standard compound interest calculator?
This one uses a business day basis (252) instead of calendar days (365). It is ideal for CDBs, LCIs, and other securities that follow the business day calendar.