A correlation of flame heights is presented for recent experiments of merging group fires produced from arrays of gaseous burners. The correlation is based on two considerations: a) the air entrainment up to the flame height is proportional to the stoichiometric requirements for combustion of the fuel and b)the air entrained is equal to the side area of the plume multiplied by an entrainment velocity proportional to the square root of the vertical distance from the source. This correlation is applicable for an array of merging fires as recent results verify. Justification for merging of the investigated group fires is given together with comparison with older work.