How this calculator works
Kitchen measures mix two different quantities. Grams, kilograms, ounces and pounds are masses. Cups, millilitres, tablespoons, teaspoons and fluid ounces are volumes. Converting inside one group is a fixed ratio, but converting between the groups needs the density of the ingredient. This converter stores a grams-per-cup value for each ingredient from USDA FoodData Central and uses it for every direction. The volume choices are kept separate because a US customary cup of 236.588 mL, a US legal cup of 240 mL and a metric cup of 250 mL are all called a cup in different recipes.
Formula
grams = volume in millilitres x density in grams per millilitre. millilitres = grams / density. For a mass start, volume = amount x mass-unit grams / density. For a volume start, mass = amount x volume-unit millilitres / 1000 x density. One US cup = 236.588 mL, one tablespoon = 14.787 mL, one teaspoon = 4.929 mL and one fluid ounce = 29.574 mL.
Worked example
A recipe calls for 2 US cups of all-purpose flour. Two cups is 473.18 mL, and at 0.528 g/mL that is 250 g. The same 2 cups of granulated sugar is 473.18 x 0.845 = 400 g, and 2 cups of honey is 473.18 x 1.433 = 678 g. This is why a cup of honey cannot be swapped for a cup of flour by weight.
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Frequently asked questions
Which cup does the calculator use by default?
The US customary cup of 236.588 mL, the measure used in most American recipes and in the USDA household-measure data. Switch to the 250 mL metric cup for Canadian, Australian and many European recipes, or to the 240 mL US legal cup for nutrition labelling.
Why are fluid ounces different from ounces?
A fluid ounce is a volume of 29.574 mL. An ounce is a mass of 28.350 g. They are close for water but not for flour, oil or honey. This converter lists both only where they make sense: fluid ounces under volume, ounces under mass.
How accurate are the density values?
Good for liquids and pastes, approximate for dry powders. A spooned and levelled cup of flour is about 125 g, but a scooped cup can reach 145 g. The density table lets you see the figure used and pick a custom density from your own measurement.
Can I convert between ounces and fluid ounces directly?
Only with a density. Choose the ingredient and start from ounces of weight, then read the fluid-ounce output. For water, 1 ounce of weight is about 0.959 fluid ounces; for all-purpose flour it is about 1.81 fluid ounces.