Hello there! When measuring all-purpose wheat flour for cost calculations, precision is indeed key. A level tablespoon of wheat flour typically weighs about 8 grams. A heaped tablespoon, which includes a mound on top, usually holds roughly 12 to 15 grams, depending on how high it is piled and how settled the flour is in the container.
As for your question regarding brands, yes, different brands and types (such as bleached versus unbleached or bread flour versus all-purpose) can slightly affect the density due to milling processes and moisture content. However, for most bulk cooking and general meal prepping, using 8 grams for level and 14 grams for heaped will give you a very solid baseline for your spreadsheets.