Example:
15 keV = 5.7401e-19 calorie (nutritional)
1 keV = 3.826733e-20 calorie (nutritional) | 1 calorie (nutritional) = 2.613195e+19 keV
Conversion Steps:
15 × (1.602177e-16 / 4186.8) = 5.7401e-19