Work out fire load density instantly with clear inputs, formula shown and shareable results.
Fire load density is the total heat that could be released by the combustible contents divided by the floor area, in megajoules per square metre. It is often quoted as an equivalent mass of wood, at 18 MJ/kg, and it drives required fire resistance periods and sprinkler hazard classification.
Fire load density
MJ/m² = combustible mass x calorific value / floor area
Wood equivalent
kg/m² = MJ/m² / 18
Preliminary estimate only. Fire load assessment and the resulting fire resistance requirements must be determined by a qualified fire engineer to the applicable code.
MJ/m² = combustible mass x calorific value / floor area. Fire load density is the total heat that could be released by the combustible contents divided by the floor area, in megajoules per square metre.
Fixed combustible construction such as timber framing and linings is added to the movable contents where it can contribute to the fire. Non-combustible structure is excluded.
This calculator takes 3 inputs: Mass of combustible contents, Average calorific value, Floor area. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.