Enter the heat release rate of the fire to calculate the estimated flame height using Thomas’ formula.

Flame Height Formula

The following formula is used to calculate the flame height:

H_f = 0.235 * Q^{2/5}


  • H_f is the flame height (meters)
  • Q is the heat release rate (kW)

To calculate the flame height, use Thomas’ formula where the flame height is proportional to the heat release rate raised to the power of 2/5.

What is Flame Height?

Flame height is the distance from the base of a fire to the top of the visible flame. It is an important parameter in fire safety and engineering as it relates to the potential for fire spread, heat release, and the effects on surrounding structures and environments.

How to Calculate Flame Height?

The following steps outline how to calculate the flame height:

  1. First, determine the heat release rate (Q) of the fire in kilowatts (kW).
  2. Next, use the formula H_f = 0.235 * Q^{2/5} to calculate the flame height (H_f).
  3. Finally, enter the heat release rate into the calculator to get the flame height.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Heat release rate (Q) = 500 kW