A simplified method is presented for calculating mean major species concentrations (02, C02, CO) in turbulent fires for any fuel given the species distribution of the same fuel in a laminar diffusion flame. This method, verified by extensive measurements, uses a probability distribution function (PDF) for the conserved scalar in turbulent fires together with a uniform mixedness parameter throughout the flames, first proposed in this work. For minor species concentrations (e.g., NOx, soot) that also depend on the local Kolmogorov straining rates of turbulence, the present method might be extended by including the distribution of turbulent straining rates in a fashion strongly suggested by recent evidence of soot-flame radiation and NOx yield in turbulent diffusion flames. Finally, based on the present method, an integral model is outlined for turbulent buoyant jet flames.