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
100 x 1 g = 100 g
100 g / 0.528344 g/mL = 189.2706 mL
189.2706 mL / 1 mL = 189.2706
Results are general information, not financial, tax, legal, medical or engineering advice.