Measuring ingredients by volume when a recipe calls for weight is a very common kitchen challenge, but you can get remarkably close using standard measuring cups and spoons. Because different pantry staples have significantly different densities, 100 grams will look quite different depending on what you are preparing.
For all-purpose flour, the density is relatively light. A level standard cup of flour weighs approximately 120 to 125 grams. To measure roughly 100 grams, you should aim for about 3/4 cup, or roughly 12 to 13 level tablespoons. For the best consistency, spoon the flour gently into your measuring cup and sweep the top level with a flat edge rather than scooping directly from the bag, which can pack it down and add unintended weight.
For uncooked white rice, the grains are considerably denser. A level cup weighs around 190 to 200 grams, meaning 100 grams corresponds almost exactly to 1/2 cup (or 8 level tablespoons).
For butter, standard stick packaging provides a very convenient reference. In regions where butter is sold in 113-gram sticks (8 tablespoons), 100 grams is equivalent to 7 tablespoons, or one whole stick minus one tablespoon. If you are working with a solid block, 1/2 cup of packed butter is 113 grams, so shaving off about one tablespoon will leave you with roughly 100 grams.
For granulated sugar or common liquids, 100 grams also follows straightforward guidelines. Granulated white sugar weighs about 200 grams per cup, making 100 grams equal to 1/2 cup. Water and milk have a density close to 1 gram per milliliter, so 100 grams equals 100 milliliters, which is just under 1/2 cup (about 7 tablespoons).
Keeping these general benchmarks in mind should give you dependable results and keep your dishes well-balanced on busy weeknights.