For precision, French chefs—pastry chefs in particular—weigh all of their ingredients, and scales are a basic tool in many French home kitchens. Measurements are given here in both the American (imperial) and French (metric) systems. The metric system is easier and more exact, but since few home cooks have scales in the US, quantities are given, wherever possible, in cup and spoon measurements. It is necessary to bear in mind, however, that the conversion of quantities inevitably results in some rounding down or up. For the more straightforward recipes, these small differences will have little impact on the end result. However, we recommend weighing your ingredients wherever possible, and advise against mixing imperial and metric measurements in the same recipe.