# Burning Index

**Burning Index (BI)** is a number used by the National Oceanic and Atmospheric Administration (NOAA) to describe the potential amount of effort needed to contain a single fire in a particular fuel type within a rating area. The National Fire Danger Rating System (NFDRS) uses a modified version of Bryam's equation for flame length - based on the Spread Component (SC) and the available energy (ERC) - to calculate flame length from which the Burning Index is computed.^{[1]}

The equation for flame length is listed below:^{[1]}

where:

*j*is a scaling factor,*SC*is the spread component,- and
*ERC*is the Energy Release Component.

Consequently, the equation for the Burning Index is:^{[1]}

where is the Burning Index scaling factor of (10/ft). Therefore, dividing the Burning Index by 10 produces a reasonable estimate of the flame length at the head of a fire. A unique Burning Index (BI) table is required for each fuel model.^{[1]}