The weight of 1 cup of all-purpose flour can vary slightly based on how it is measured and the humidity, but as a general guideline, 1 cup of all-purpose flour is approximately 120 to 125 grams.
If you need precise measurements for a specific recipe, it's always best to use a kitchen scale to weigh the flour for accuracy, as the volume can be affected by how compacted the flour is in the cup. Measuring by weight is more reliable in baking, where precise ratios are essential for successful results.