Example:
15 Btu (IT), Btu = 3.779936 calorie (nutritional)
1 Btu (IT), Btu = 0.251996 calorie (nutritional) | 1 calorie (nutritional) = 3.968321 Btu (IT), Btu
Conversion Steps:
15 × (1055.05585262 / 4186.8) = 3.779936417