How to Measure Flour
Ingredients can be measured either by volume (ex. cups, tablespoons) or weight (ex. grams, kilograms, pounds, ounces). The most accurate way to measure flour (and most ingredients, really) is by weight, using a kitchen scale. Good recipe books often include weight and volume measurements so, wherever possible, go by weight.
When measuring by volume, spoon flour into the measuring cup and level it off with the back of a knife. This is important because a cup of unpacked flour will contain considerably less flour than a cup of packed flour. If you dip your measuring cup into the flour bin and scoop some out, your flour will be packed down and you will end up with too much. This is why measuring by weight is best. A kilogram of flour is the same amount, no matter how it is scooped.