Brightness variability has been confirmed by other researchers in some spectral bands, but it is unclear what the actual variable type is. No significant spectral variation has been found. WOH G64 is classified as a luminous M class supergiant and is likely to be the largest star and the most luminous and coolest red supergiant in the LMC, although another red supergiant IRAS 05280-6910 may have a larger radius but is considered highly uncertain. The combination of the star's temperature and luminosity places it toward the upper right corner of the Hertzsprung–Russell diagram. The star's evolved state means that it can no longer hold on to its atmosphere due to low density, high radiation pressure, and the relatively opaque products of thermonuclear fusion. It has an average mass loss rate of 3.1 to per year, among the highest known and unusually high even for a red supergiant. WOH G64 was originally calculated to be around between based on spectroscopic measurements assuming spherical shells, suggesting an initial mass of and consequently larger values for the radius of . In 2007 Ohnaka et al. using the Very Large Telescope (VLT) calculated that the star has a bolometric luminosity of , suggesting an initial mass of , and a radius around based on the assumption of an effective temperature of and radiative transfer modelling of the surrounding torus. In 2009, Levesque calculated an effective temperature of by spectral fitting of the optical and near-UV SED. Adopting the Ohnaka luminosity with this new temperature gives a radius of but with a margin of error of 5%. Ignoring the effect of the dusty torus in redirecting infrared radiation, estimates of based on a luminosity of and an effective temperature of 3,372 - have also been derived. Those physical parameters are consistent with the largest galactic red supergiants found elsewhere such as Westerlund 1-26, VY Canis Majoris and NML Cygni and with theoretical models of the coolest, most luminous and largest possible cool supergiants (e.g. the Hayashi limit or the Humphreys–Davidson limit). A 2018 paper gives a luminosity of and an effective temperature of , based on optical and infrared photometry and assuming spherically-symmetric radiation from the surrounding dust. This suggests a radius of about . WOH G64 has a possible late O-type dwarf companion of a bolometric magnitude of −7.5 or a luminosity of , which would make WOH G64 a binary star although there has been no confirmation of this observation and the intervening dust clouds makes the study of the star very difficult.