CDB Calculator: How to Calculate Bank Certificate Returns
Learn how to calculate CDB returns, compare rates, understand taxation, and choose the best Bank Certificate for your investments in Brazil.
CDB (Bank Certificate of Deposit) is one of the most popular investments among Brazilians seeking higher returns than savings accounts with guaranteed security. Understanding how to calculate its returns is essential for making smarter investment decisions and comparing offers from different banks.
With the CDB calculator you can simulate different scenarios and discover exactly how much your money will yield at each financial institution.
What is CDB
CDB works as a loan you make to the bank. In return, the institution pays interest on the invested amount during the agreed period. It’s a safe way to invest your money with predictable returns.
Types of CDB
There are three main types of CDB in the Brazilian market:
- Fixed-rate CDB: interest rate defined at the time of investment (e.g., 12% per year)
- Post-fixed CDB: returns tied to CDI (e.g., 120% of CDI)
- Hybrid CDB: combines fixed rate + indicator (e.g., 6% + IPCA)
FGC Guarantee
The Credit Guarantee Fund (FGC) protects CDB investments up to R$ 250,000 per CPF, per financial institution. This guarantee makes CDB a very low-risk investment, equivalent to savings account security.
The limit is renewed every 4 years, allowing diversification across different banks to expand protection.
How to calculate returns
Fixed-rate CDB
In fixed-rate CDB, the calculation is straightforward using compound interest:
Formula: Amount = Principal × (1 + rate)^time
Example: R$ 10,000 invested for 2 years at 11% per year
Amount = 10,000 × (1.11)² = R$ 12,332.10
Gross return = R$ 2,332.10
Post-fixed CDB (CDI)
For CDI-linked CDB, you need to track the current Selic rate (which influences CDI):
- CDI today is close to 11.25% per year
- CDB 120% of CDI = 13.5% per year
- CDB 100% of CDI = 11.25% per year
Example: R$ 5,000 in CDB 110% CDI for 1 year
Effective rate = 11.25% × 1.10 = 12.375% per year
Gross return = 5,000 × 0.12375 = R$ 618.75
Daily liquidity CDB
Daily liquidity CDBs allow redemption at any time while maintaining proportional returns for the period. The calculation considers business days invested:
Daily return = (Annual rate ÷ 252 business days) × days invested
CDB Taxation
Progressive IR table
Income Tax follows a regressive table - the longer the term, the lower the tax:
| Investment period | IR Rate |
|---|---|
| Up to 180 days | 22.5% |
| 181 to 360 days | 20% |
| 361 to 720 days | 17.5% |
| Over 720 days | 15% |
IOF in the first 30 days
IOF (Tax on Financial Operations) applies only in the first 30 days:
- Varies from 96% on day 1 to 0% on day 30
- Discourages very quick redemptions
- Doesn’t apply after 30 calendar days
Example: Redemption on day 15 = IOF of approximately 46% on returns
Practical simulation
Different amounts
Compare net returns (after taxes) for different amounts:
| Invested amount | CDB 115% CDI (2 years) | Net return |
|---|---|---|
| R$ 1,000 | Rate: 12.94% p.a. | R$ 220.15 |
| R$ 10,000 | Rate: 12.94% p.a. | R$ 2,201.50 |
| R$ 50,000 | Rate: 12.94% p.a. | R$ 11,007.50 |
Considers 17.5% IR for 2-year investments
Bank comparison
Different institutions offer varying CDI percentages:
- Digital banks: 120% to 130% of CDI
- Major banks: 90% to 110% of CDI
- Mid-size banks: 105% to 125% of CDI
- Brokerages: 115% to 135% of CDI
Use the CDB calculator to compare real scenarios with your conditions.
CDB vs savings account
Savings accounts yield only 70% of Selic when it’s above 8.5% per year:
| Investment | Current yield | CDB advantage |
|---|---|---|
| Savings | 7.87% per year | - |
| CDB 100% CDI | 11.25% per year | +42.9% |
| CDB 120% CDI | 13.5% per year | +71.5% |
Values considering Selic at 11.25% per year
How to choose the best CDB
Essential criteria
- CDI percentage offered (higher is better)
- Maturity period (affects taxation)
- Minimum investment amount
- Liquidity (daily or at maturity)
- Bank stability (credit rating)
Diversification strategy
Distribute your resources considering the FGC limit:
- Maximum R$ 250,000 per bank
- Diversify across 2-3 institutions
- Combine different terms for laddering
Risks and precautions
Credit risk
Although protected by FGC, banks can fail. Prefer institutions with:
- AA rating or higher
- Solid market history
- Good reputation with the Central Bank
Liquidity risk
CDBs without daily liquidity lock up your money until maturity. Always maintain an emergency fund in liquid investments.
Inflation
Fixed-rate CDBs can lose purchasing power if inflation rises above the contracted rate. In inflationary scenarios, prefer post-fixed CDBs.
Frequently Asked Questions
What’s the minimum amount to invest in CDB?
Most banks accept investments from R$ 1,000. Digital banks often have lower minimums, starting at R$ 100 or R$ 500.
Does CDB yield more than savings accounts?
Yes, CDBs typically yield 30% to 70% more than savings accounts. With current Selic rates, a 100% CDI CDB already outperforms savings by over 40%.
Can I redeem CDB before maturity?
It depends on the product. Daily liquidity CDBs allow redemption at any time. CDBs without liquidity can only be redeemed at maturity, except in specific situations.
How is Income Tax charged on CDB?
IR is automatically deducted at redemption, following the regressive table. No need to declare at source, only in annual tax returns.
Is it worth investing in CDB with high Selic?
Yes, high Selic favors post-fixed CDBs. With CDI near 11.25%, CDBs offer attractive real returns even after taxes.
How much does R$ 10,000 yield in CDB per month?
In a 120% CDI CDB (13.5% per year), R$ 10,000 would yield approximately R$ 107 net per month, considering 22.5% IR for short-term investments.
Does CDB protect against inflation?
Post-fixed CDBs offer partial protection, as CDI tends to rise with inflation. For full protection, consider Treasury IPCA+ or inflation-indexed hybrid CDBs.