Volume is not weight
A cup measures volume while grams measure mass. Equal volumes of flour, sugar, butter and honey have different weights because their densities differ.
Packing changes the result
Scooped flour can be much denser than lightly spooned flour, while brown sugar is often intentionally packed. A conversion table must state its measuring convention.
Use a scale for repeatability
For baking, weighing ingredients normally gives more repeatable results and simplifies recipe scaling.
Practical checklist
- Select the exact ingredient before converting.
- Keep the same cup standard throughout a recipe.