This, too: if E = hc/λ and E = mc², then we can combine both as hc/λ = mc². Rearranging this shit you get m = h/λc. Since h/c = 2.2*10⁻⁴²kg*m, you’d get:

Photon colour	wavelength (in nm)	“Weight” (in 10⁻³⁶kg = 10⁻³qg)
red	650	3.4
yellow	600	3.7
green	550	4.0
blue	450	4.9

…BLOODY ULTRAVIOLET IS MAKING ME FAT!