TL;DR / Quick Summary: Converting US cups to grams cannot use a single multiplier because cups measure volume while grams measure mass. One cup of all-purpose flour weighs approximately 120g, granulated sugar weighs 200g, and butter weighs 227g. For consistent baking results, always use ingredient-specific density factors or a digital kitchen scale.
How Do You Convert US Cups to Grams Accurately?
A standard US cup equals 236.6 milliliters of liquid volume. To convert that volume into metric grams, multiply the volume in cups by the ingredient’s bulk density (grams per cup). For example, 1.5 cups of all-purpose flour equals 1.5 × 120g = 180 grams.
Because powdered and granular ingredients pack differently depending on humidity and scooping technique, professional pastry chefs weigh ingredients by mass rather than scooping by volume.
Ingredient Conversion Chart: US Cups to Grams
The table below outlines standard weight equivalents for common baking staples based on the “spoon-and-level” method:
| Ingredient | 1/4 Cup | 1/2 Cup | 1 Cup | 1 US Tbsp |
|---|---|---|---|---|
| All-Purpose Flour | 30 g | 60 g | 120 g | 7.5 g |
| Bread Flour | 32 g | 64 g | 127 g | 8 g |
| Granulated White Sugar | 50 g | 100 g | 200 g | 12.5 g |
| Brown Sugar (Packed) | 55 g | 110 g | 220 g | 13.8 g |
| Powdered / Icing Sugar | 30 g | 60 g | 120 g | 7.5 g |
| Unsalted Butter | 57 g | 113.5 g | 227 g | 14.2 g |
| Cocoa Powder (Unsweetened) | 25 g | 50 g | 100 g | 6.25 g |
| Rolled Oats | 22.5 g | 45 g | 90 g | 5.6 g |
| Honey / Molasses | 85 g | 170 g | 340 g | 21.2 g |
| Water / Whole Milk | 60 g | 120 g | 240 g | 15 g |
Why Does One Cup of Flour Weigh Less Than One Cup of Sugar?
Flour consists of finely milled wheat grains separated by microscopic air pockets, resulting in a low density of roughly 0.51 g/cm³. In contrast, granulated sucrose forms crystalline granules that pack tightly together with minimal air voids, yielding a density of roughly 0.85 g/cm³.
When a recipe calls for “1 cup”, using a single liquid-measuring cup or scooping directly from the bag can compress flour and pack in up to 150 grams—a 25% surplus that turns tender cakes into dry bricks.
What Is the “Spoon and Level” Method?
If you must measure without a kitchen scale, never scoop the measuring cup directly into the flour canister. Instead, fluff the flour with a fork, spoon it gently into your measuring cup until overflowing, and sweep a straight knife across the rim to level the excess.
Frequently Asked Questions
What is the difference between US Customary Cups and Metric Cups?
A US Customary Cup measures 236.59 ml (often rounded to 240 ml on nutrition labels). A Metric Cup, standardized in Australia, New Zealand, and parts of the Commonwealth, is exactly 250 ml. Using a metric cup for a US recipe adds about 5.6% extra volume.
How much does 1 stick of American butter weigh?
One American stick of butter equals 1/2 US cup, 8 tablespoons, 4 ounces, or 113.4 grams. Two full sticks equal exactly 1 US cup or 227 grams.
Does sifted flour weigh the same as unsifted flour?
Yes in mass, but not in volume. Sifting introduces air, meaning 1 cup of sifted flour weighs only 100–110g, whereas 1 cup of unsifted dipped flour can weigh 140–150g. Always weigh on a scale to bypass aerated volume discrepancies.
Can I use Kitchen Converter without an active internet connection?
Yes. Kitchen Converter stores all conversion tables and formulas locally in your browser or native mobile app, allowing instant offline calculation on your kitchen counter.