All-purpose (plain) white flour - USDA FoodData Central 168894, "Wheat flour, white, all-purpose, enriched, bleached", portion 1 cup = 125 g
Worked out from USDA FoodData Central, SR Legacy food portion data and 1 other source.
Flours and other compressible dry goods vary by 10-20% with scooping technique. The USDA figure is the spooned-and-levelled reference; a scoop straight from the bag weighs more.
How this is worked out
3 steps
30 x 1 g = 30 g
30 g / 0.528344 g/mL = 56.7812 mL
56.7812 mL / 14.78676478125 mL = 3.84
Results are general information, not financial, tax, legal, medical or engineering advice.