Estimates of Alnilam's properties vary. Crowther and colleagues, using stellar wind and atmospheric modelling in 2006, came up with a luminosity 275,000 times that of the Sun (), and effective temperature of 27,000 K and a radius 24 times that of the Sun (). Searle and colleagues, using CMFGEN code to analyse the spectrum in 2008, calculated a luminosity of , an effective temperature of 27,500 ± 100 K and a radius of . Analysis of the spectra and age of the members of the Orion OB1 association yields a mass 34.6 times that of the Sun ( on the main sequence) and an age of 5.7 million years.