How this works
Recipe measurements come in two flavours: volume (cups, tablespoons, millilitres) and weight (grams, ounces). Volume-to-volume and weight-to-weight conversions are simple multiplications — 1 cup = 240 ml, 1 oz = 28.35 g, etc. The tricky part is converting across the two: how many grams is a cup of flour? Depends on the ingredient. Flour is light and airy (~125 g per cup), sugar is dense (~200 g per cup), butter is denser still (~227 g per cup), water sits at exactly 240 g per cup by definition. Without specifying the ingredient, cups-to-grams conversion is meaningless.
The US, UK, and most non-baking-obsessed countries use volume measures in everyday cooking, while serious bakers and metric-region recipes use weight (grams). Weight is more accurate — a "cup of flour" varies by 20% depending on whether you scoop or sift, while 125 g is exactly 125 g. If you're scaling a recipe up or down, working in weight avoids compounding measurement errors. This calculator handles both directions and uses standard ingredient densities published by King Arthur Baking and the USDA — close to what professional bakeries use as default.
The formula
Densities are population averages from baking references; actual weight varies ±10% with sifting, packing, brand and humidity. For exact baking results, weigh ingredients on a scale rather than trusting volume measures.
Example calculation
- 2 cups of flour to grams.
- 2 × 125 g/cup = 250 g.
Frequently asked questions
Why is "1 cup of flour" not always the same weight?
Compaction. Scoop flour out of the bag aggressively and you pack it; gently spoon and level and you don't. The difference is 20–30%. Sift first and the spread is even larger. Standard references give "spoon-and-level" weights (125 g/cup for AP flour); if a recipe was developed by scoop-and-pack, you'll need closer to 150 g/cup. Weighing avoids the whole problem.
Are US cups the same as UK / metric cups?
No. The US legal cup is 240 ml. The US "customary" cup (used in older recipes) is 236.6 ml. The UK / Commonwealth metric cup is 250 ml. Australian cups are 250 ml; some older British recipes use a 284 ml "imperial cup". This calculator uses the US legal cup (240 ml) as default since it's by far the most common online. For UK or Australian recipes, multiply quantities by ~1.04 (250/240) to be exact, but in practice the difference rarely matters in cooking.