Master the LEFTB Function: Extract Text by Bytes in Excel

In this scenario, A2 contains '产品-ABC123'. Since each Chinese character occupies 3 bytes in UTF-8 encoding, extracting 6 bytes captures exactly the two Chinese characters '产品'. This is more precise than using LEFT(A2,2) which would count characters rather than bytes, potentially causing encoding issues when the data is processed by legacy systems.

Cyrillic characters in Windows-1251 encoding use 1 byte per character, so 8 bytes equals 8 Cyrillic characters. However, in UTF-8, Cyrillic characters use 2 bytes each, so 8 bytes would extract 4 Cyrillic characters. This demonstrates why LEFTB requires understanding your data's encoding. Using LEFTB ensures byte-accurate extraction regardless of the script system, preventing corruption when data transfers between systems with different character set assumptions.

This formula combines LEFTB with LENB and IF to ensure data compliance. It checks whether the total byte length of the customer data (C4) is 20 bytes or less. If compliant, it safely extracts up to 20 bytes using LEFTB. If the data exceeds the limit, it returns an error message. This prevents data truncation errors in legacy systems and ensures smooth integration between modern Excel environments and older systems with strict byte limitations.

This combination checks the total byte length of text in A1 using LENB. If it exceeds 20 bytes, LEFTB extracts exactly 20 bytes; otherwise, it returns the entire text. This is essential for systems with byte-length limitations, ensuring data never exceeds maximum thresholds while preserving shorter entries intact.

This formula finds the position of a hyphen delimiter and multiplies by 2 to approximate byte position (useful for languages where characters are typically 2 bytes). It extracts all bytes up to the delimiter. This combines pattern-matching with byte-level extraction for more sophisticated text processing in international datasets.

This formula wraps LEFTB with IFERROR to gracefully handle errors when B1 contains non-numeric values or when A1 is invalid. The INT function ensures B1 is converted to an integer. This combination creates production-ready formulas that don't break when encountering unexpected data, essential for automated reporting and data processing pipelines.

Text containing emoji or special Unicode characters (e.g., '👍Hello' or '❤️World')

Behavior: Emoji in UTF-8 typically occupy 4 bytes each. =LEFTB('👍Hello',4) extracts only the emoji, =LEFTB('👍Hello',5) extracts emoji plus 'H'. This can result in partial character extraction if byte boundary doesn't align with character boundaries.

Solution: Use LENB to check total bytes before extraction. Consider using FIND to locate character boundaries rather than relying on fixed byte counts with emoji-containing text.

Emoji handling varies by system locale and UTF-8 implementation. Always test with actual emoji data in your Excel environment.

Text with line breaks or special formatting characters (e.g., text containing CHAR(10) for line feed)

Behavior: Line break characters (CHAR(10)) occupy 1 byte each. =LEFTB('Line1' & CHAR(10) & 'Line2',6) extracts 'Line1' plus the line break character, potentially breaking intended formatting.

Solution: Use SUBSTITUTE to remove or normalize line breaks before applying LEFTB: =LEFTB(SUBSTITUTE(A1,CHAR(10),""),10)

This is particularly important when importing text from other sources or when working with multi-line cell content.

Null or zero value for num_bytes parameter (e.g., =LEFTB(A1,0))

Behavior: =LEFTB(A1,0) returns an empty string "", even if A1 contains substantial text. This is by design but can be unexpected for users unfamiliar with byte-counting functions.

Solution: Use IF to validate num_bytes before applying LEFTB: =IF(B1>0,LEFTB(A1,B1),A1) to handle zero values appropriately based on business logic.

This behavior differs from some other text functions and should be documented in formulas to prevent confusion during maintenance.