flame Unit Converter

Definition of flame unit

The flame is a historical unit of luminous intensity, representing the light output of a specified standard flame. It predates modern photometric units such as the candela, though its exact value varied with the prescribed burner and fuel.

History of flame unit

Flame-based photometry developed before electrically powered light sources and internationally agreed standards. In the nineteenth century, scientists and metrologists compared lamps and flames to establish reproducible luminous intensities. A “standard flame” typically specified a burner, fuel, flame dimensions, and operating conditions, because brightness changed with each variable. Different countries and laboratories consequently used nonidentical flame values. As photometric science matured, the candlepower and later the candela replaced these practical references. The flame therefore survives mainly as a historical term in older lighting literature and conversion tables.

Applications of flame unit

Today, flame is rarely used for specifying illumination, since the candela and lux provide standardized measurements. It may appear in historical documents, museum labels, old engineering manuals, and unit-conversion software. Researchers can also encounter it when interpreting legacy photometric data, especially descriptions of candle or gas lighting, theatrical effects, street lamps, and early photographic equipment.

Complete list of flame unit conversion