LMW

lmW is not a standard scientific term or unit. In practice, it can appear as an informal shorthand, an acronym with unrelated meanings, or a product designation, and its intended meaning depends on the context. The closest established term is lumens per watt, abbreviated lm/W, which expresses luminous efficacy.

Where it appears in lighting documentation or catalogs, “lmW” may be used loosely to indicate a metric combining brightness and power, but this usage is nonstandard and can be ambiguous. In software, hardware datasheets, or measurement notes, “lmW” is sometimes used as a variable name, label, or placeholder rather than as a defined unit. Users should rely on the accompanying definitions to interpret the value.

Luminous efficacy is defined as the ratio of luminous flux, measured in lumens (lm), to the electrical input power, measured in watts (W). Its standard unit is lm/W; values expressed in lm/W indicate how efficiently a light source converts electrical power into visible light. Confusion can arise when “lmW” is seen without context.

See also: Lumen, Watt (unit), Luminous efficacy, Photometry.