How it works
What this calculadora actually does
Most Finance tools bury the calculation. Fixed Income calculadora (Brasil) shows it. Punch in your figures, read the working, share the URL if you need a second opinion.
Small rate differences stack up over years — always run the maths before signing. Pull last month’s statement open on another tab — then run the sums and the rest of this page explains what the answer means.
Compare CDB, LCI, LCA, Tesouro and poupança side by side with the same amount, period and the correct regressive IR table.
Following the method end to end
Here's what happens when you plug real numbers in.
Compare CDB, LCI, LCA, Tesouro and poupança side by side with the same amount, period and the correct regressive IR table.
Moments this tool earns its keep
Fixed Income calculadora (Brasil) is aimed at people arriving with questions like these:
- "Comparar CDB LCI LCA"
- "Melhor renda fixa hoje"
- "IR renda fixa"
- "What is fixed income brasil"
- "How to calculate fixed income brasil"
- "Fixed income brasil formula"
Where the number stops being useful
Every tool has an edge where it stops being the right answer. Fixed Income calculadora (Brasil) is no exception:
- For legally binding tax or medical decisions — cross-check with HMRC, NHS or a qualified professional.
- For very large or very small extremes the rounding error outgrows the useful precision.
- When the underlying rate or threshold has changed since the page was last reviewed — always verify with the primary source.
- When the input you have is already a derived figure (net of something) — feeding it in as "gross" will double-subtract.
Mistakes we see over and over
Every time you run the sums for a new scenario, one of these creeps in — it's worth knowing them ahead of time.
- Assuming the UK and US versions of the same unit are interchangeable — they're not.
- Typing a comma where the tool expects a dot (or vice versa).
- Rounding early — particularly painful in percentages and compound growth.
- Ignoring the time window: a 'per year' answer makes no sense with a monthly input.
- Treating the answer as private: screenshots are fine, but the URL always reruns cleanly.
The sources behind the numbers
Where the maths needs an external authority, we cross-check against:
- B3
- Tesouro Nacional
- Receita Federal
Works well alongside
If this question keeps coming up for you, the same cluster of tools usually comes next:
- Poupança vs CDB calculadora — Compare Brazilian poupança savings (tax-free but lower rate) against CDB (subject to IR) on the same maturity and amount.
- Tesouro SELIC calculadora — Project returns on Brazilian Tesouro SELIC (LFT) with daily marked-to-market yield, custody fee and IR regressive table.
- Tesouro IPCA+ calculadora — Project returns on Tesouro IPCA+ (NTN-B) — real yield plus inflation (IPCA), IR regressive table and reinvestment.
- CDI calculadora — Brazilian CDI-indexed investments — apply percentage-of-CDI (e.g. 110% CDI) returns and net-of-IR tax.
How we keep this accurate
Our calculadoras run on pure, unit-tested functions — the same logic lives in the browser and in the CI test suite. When tax rates, thresholds or official figures move, the update lands within 24 hours of the announcement. You can read the editorial policy and corrections policy.
Found an out-of-date number on Fixed Income calculadora (Brasil) or anywhere else in the Finance toolkit? Send it to the editorial desk and we'll patch it. Or browse the full calculadora directory for the next tool you need.