Contact
12 programs
Explore the site

LEFTB Function (LibreOffice Calc)

Text Beginner LibreOffice Calc

Learn the LEFTB function in LibreOffice Calc: Returns the first character or characters of a text, with DBCS.

Verification status: Official documentation referenced; example outcomes independently reasoned or arithmetically checked where stated. Not executed in LibreOffice Calc. How formula examples are checked

Validation scope: References to observed, native-tested, or executed results below describe the saved LibreOffice Calc 25.2.3.2 Linux test evidence dated 12 October 2026. On 13 October, its script and artifact hashes, all 86 ODS/JSON case pairs, and the current official function documentation were checked; CJK/ASCII worked examples were independently reasoned through. Calc was not rerun for this review. Historical observations do not certify other versions, platforms, locales, or workbook imports.

LEFTB takes a specified number of DBCS-style byte units from the beginning of a string. Unlike LEFT, it can replace a partial double-byte character with an ordinary space. This matters when examining legacy fixed-width or double-byte text and when comparing Calc to other spreadsheet engines.

Function purpose: byte-width prefix versus character prefix

Use LEFT when you mean a number of characters. Use LEFTB only when a DBCS-oriented byte-width limit is appropriate. The difference is visible with CJK characters. =LEFT("中国";1) selects the first character, 中; =LEFTB("中国";1) instead returned one plain space in the tested Calc environment because one byte cannot hold a complete two-byte character. [LO-LEFTB] [NATIVE]

The blank-looking result is not necessarily an empty string. The official Calc Help states that incomplete DBCS characters are represented using a space. This is a critical limitation if you intend to validate identifiers or remove whitespace later: the space is now part of the returned text. [LO-LEFTB]

Syntax, parameter order, and defaults

=LEFTB(Text [; Number_bytes])
Argument Required Meaning Default
Text Yes Literal text, a cell reference, or an expression converted to text. No default; omission is invalid.
Number_bytes No How many DBCS byte units to extract from the left. Fractions were truncated in native tests. 1 byte if omitted (shown by the official examples and the test results).

LibreOffice’s Help labels this as available since 4.2. The English name is LEFTB. Calc commonly uses ; between arguments, while English function names and separators are configurable under Tools → Options → LibreOffice Calc → Formula. A localized function display may differ; do not infer that an Excel comma-separated formula uses identical syntax in Calc. No separate ODF-specific alias was verified for this function. [LO-LEFTB] [LO-OPTIONS] [NATIVE]

Reproducible examples

The following results were executed in LibreOffice Calc 25.2.3.2. A ␠ denotes one ordinary ASCII space (U+0020) in the output, not an empty string; literal strings are shown inside double quotes for clarity.

Formula Observed string Explanation
=LEFTB("office";3) "off" Three Latin characters, each one unit.
=LEFTB("中国";1) "␠" Half of the first two-byte character → one space.
=LEFTB("中国";2) "中" Exactly one complete DBCS character.
=LEFTB("中国";3) "中␠" Second character is incomplete → trailing space.
=LEFTB("中国";4) "中国" Entire string.
=LEFTB("中国") "␠" Omitted byte count defaults to 1.
=LEFTB("中国";0) "" Zero-byte request → empty result.
=LEFTB("中国";5) "中国" A request longer than the input returns all text.

The documentation supplies the CJK/ASCII base cases; the additional zero, default, and out-of-range cases were independently checked in the native workbook. Do not replace the displayed space with a missing cell value when copying an output into another formula. [LO-LEFTB] [NATIVE]

Mixed text: a prefix that ends on a partial character

Consider the string A中B: A consumes one DBCS unit, 中 consumes two and B consumes one, for a total of four units in the tested engine. [NATIVE]

Formula Result Why
=LEFTB("A中B";1) "A" First ASCII byte.
=LEFTB("A中B";2) "A␠" Second requested unit is only half of 中.
=LEFTB("A中B";3) "A中" Three units include the full Chinese character.
=LEFTB("A中B";4) "A中B" All four units.

These four formulas were all native-tested in LibreOffice Calc 25.2.3.2. LEFTB is not equivalent to slicing raw bytes from a UTF-8 file and decoding the result. Its replacement-space behavior can affect exact-string comparisons. [NATIVE] [LO-LEFTB]

Follow along with a cell reference

Enter 中A in J2, then enter:

=LEFTB(J2;3)

Native-tested output: 中A. A budget of three covers the two-unit ideograph plus one-unit Latin suffix. With =LEFTB("中A";1), Calc returned a single space instead, not 中. [NATIVE]

Advanced patterns

Validate a stable ASCII prefix

If a legacy identifier must start with two ASCII letters, use a comparison that does not depend on slicing inside CJK characters:

=IF(LEFTB("AB中";2)="AB";"OK";"CHECK")

Observed: OK in native Calc. For ordinary text identifiers not governed by a DBCS byte specification, the character-counting LEFT is simpler and avoids partial-character spaces. [NATIVE]

Build extraction with LENB

The pair LENB and LEFTB uses related DBCS semantics, but LENB(LEFTB(...)) measures the returned text, which may contain substitution spaces. For example, =LEFTB("A中B";2) returned A␠ (the second unit is a replacement space). A downstream validator must not mistake that space for the original Chinese character. This is a native-observed behavior plus a logical consequence; the nested length is not separately reported as an executed assertion here. [NATIVE]

Decimal counts, numeric text, and Unicode boundaries

=LEFTB("中国";2.9) returned 中; =LEFTB("中国";1.9) returned a space. This indicates truncation to an integer in Calc 25.2.3.2, not rounding. =LEFTB(12345;3) returned 123 because numeric input was rendered as text in that setup. Non-BMP Unicode characters and combining sequences may behave differently from DBCS-era expectations; do not use LEFTB as a general-purpose Unicode-safe truncator. Results in other locales/versions require fresh validation. [NATIVE]

Troubleshooting and error cases

Formula/problem Observed Calc 25.2.3.2 result Action
=LEFTB("中国";-1) Err:502 Use a nonnegative count.
=LEFTB("中国";"abc") #VALUE! Supply a numeric count.
=LEFTB() Err:511 Provide required Text.
=LEFTB("a";1/0) #DIV/0! Fix the upstream calculation.
Chinese text becomes a space Expected when extracting an incomplete DBCS character. Increase the byte budget to cover the complete character, or use LEFT instead.
Formulas work only with commas on another machine Formula separator setting differs. Confirm Calc’s Formula settings.

The codes are observations of the tested native build, not a cross-version guarantee. A formula that returns a space may look blank: test with LEN or put delimiters around the result to reveal it. That final troubleshooting suggestion was not separately native-executed for the saved test. [NATIVE] [LO-OPTIONS]

Cross-application compatibility

LibreOffice Calc officially supports LEFTB from version 4.2, and Google Sheets documents its own LEFTB(string, num_of_bytes) with comma-separated examples. Microsoft’s current LEFT documentation states that LEFTB is deprecated in Excel. These are documentation-only comparisons; the saved test executed formulas in LibreOffice only. Do not promise identical Unicode, locale, or edge-case behavior in Google Sheets or Excel based merely on the shared name. [LO-LEFTB] [GOOGLE-LEFTB] [MS-LEFT]

For character-count extraction see LEFT, RIGHT and MID. For DBCS operations see LENB, RIGHTB and MIDB.

Sources and verification records

Every documentation source below was accessed 2026-10-12. “Latest” LibreOffice Help displayed 26.8; executable native testing used 25.2.3.2 on Linux.