Pound Abbreviation: lb vs. lbs
NIST measurement tables use “lb” for pound. In measurement notation, the symbol itself does not become “lbs” just because the quantity is plural. General prose and informal packaging sometimes use “lbs,” but technical writing should follow the applicable measurement or house standard.
Use “lb” as the measurement symbol for both singular and plural quantities: 1 lb, 5 lb. Use “lbs” only if a nontechnical house style specifically calls for it.
Key details
Important caveats
Boundary
Consumer packaging and informal prose may use “lbs”; this guide distinguishes that convention from technical measurement notation.
Further guidance
Measurement Table
NIST Handbook 44 lists pound with the symbol “lb.”
Practical Application
In measurement notation, use the symbol “lb” for both singular and plural quantities: “1 lb” and “5 lb.” Treat “lbs” as a nontechnical house-style variant rather than the technical measurement symbol.
Reader Check
Check whether the document follows a measurement standard, packaging convention, or informal house style. Do not pluralize a technical symbol merely because the numerical quantity is plural.
Symbol Logic
Technical unit symbols are fixed forms rather than ordinary pluralized words.
Worked Example
Technical notation: “The package weighs 12 lb.” If a consumer-facing house style explicitly uses “lbs,” keep that choice confined to that style.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- NIST Handbook 44 — General Tables of Units of Measurement (opens in a new tab)National Institute of Standards and Technology · NIST table showing lb as the symbol for pound
- Writing with SI (Metric System) Units (opens in a new tab)National Institute of Standards and Technology · NIST unit-symbol rules, including no plural s on symbols