Brazilian Boleto Decoder

Modulus 10 and modulus 11 in the digitable line

In the 47-digit bank slip, the first 3 fields (9, 10 and 10 digits respectively) each carry their own check digit computed with modulus 10: every digit is multiplied by alternating weights of 2 and 1 from right to left, products above 9 have their own digits summed, and the check digit is the complement of the total sum up to the next multiple of 10. The fourth field is different: it is the general check digit of the 44-digit barcode, computed with modulus 11 over the other 43 digits, using weights that cycle from 2 to 9 from right to left.

In the 48-digit utility bill, the logic changes: instead of 3 fields fixed to modulus 10 and one general check digit fixed to modulus 11, the whole line uses a single algorithm (modulus 10 or modulus 11) selected by the barcode's 3rd digit, applied equally to all 4 blocks of 11 digits and to the general check digit.

• Bank slip: fields 1 to 3 use modulus 10, the general check digit uses modulus 11.
• Utility bill: all 4 blocks and the general check digit use the same algorithm, chosen by the 3rd digit.
• 3rd digit 6 or 7 means modulus 10; 3rd digit 8 or 9 means modulus 11.
• A single mistyped digit anywhere in the line changes the expected check digit, that is how the tool catches typos.

The due-date factor and the February 2025 rollover

The due date is not spelled out in the digitable line, it is represented by a 4-digit field called the due-date factor, which counts how many days have elapsed since a base date. This scheme has existed since the FEBRABAN standard was created, with an original base date of October 7, 1997. Since the field only has 4 digits, the largest possible value is 9999, and that counter ran out exactly on February 21, 2025.

To avoid overflowing the field, the Brazilian banking industry reset the counter to 1000 starting February 22, 2025, while switching the base date to May 29, 2022 (chosen specifically so that May 29, 2022 plus 1000 days lands on February 22, 2025, keeping the numeric value continuous). This means any boleto issued from that date onward uses the new base date, not the 1997 one. This tool computes the due date under both bases and highlights the current-base (2022) reading as the primary one, showing the legacy-base (1997) reading only as historical context.

• Legacy base date: 1997-10-07, used up to factor 9999 (2025-02-21).
• Current base date: 2022-05-29, used from factor 1000 onward (2025-02-22).
• Factor 0000 means the line does not encode a fixed due date.
• Boletos issued before 2025-02-22 that are still outstanding could, in theory, need the legacy reading.

Bank slip vs. utility bill

The fastest way to tell the two formats apart is to count the digits: 47 means bank slip (cobrança), 48 means utility bill (arrecadação). A bank slip always encodes a currency amount in reais in the line's last 10 digits. A utility bill, on the other hand, can encode either an effective amount in reais or a reference value (an index or internal code from the issuing agency, with no direct currency meaning), depending on the line's 3rd digit: 6 and 8 mean effective value, 7 and 9 mean reference value.

The utility bill's 2nd digit also identifies the segment that issued the charge: city halls, water and sanitation, electricity and gas, telecommunications, government agencies, installment books and traffic fines each have their own code. This tool reads that digit and shows the segment alongside the result.