Volume and mass answer different questions
Cups, tablespoons, teaspoons, fluid ounces, and millilitres measure volume. Grams and ounces measure mass. Equal volumes of flour, sugar, butter, and water do not have equal masses because their densities differ. A universal cups-to-grams factor therefore does not exist.
Even an ingredient-specific conversion is an estimate unless the source defines how the ingredient was prepared. Flour can settle or compact; brown sugar may be loosely filled or firmly packed; chopped ingredients leave air gaps. For repeatable baking, use the recipe’s gram values and a kitchen scale when they are available.
Identify the recipe’s cup and spoon convention
A US customary cup is 236.5882365 mL, although recipes and nutrition labels often use a rounded 240 mL. A common metric cup is 250 mL. These values are close enough to look interchangeable but can produce a noticeable difference across several cups.
US customary volume gives 1 cup = 16 tablespoons and 1 tablespoon = 3 teaspoons. The corresponding customary tablespoon is about 14.7868 mL, while a metric measuring tablespoon is commonly treated as 15 mL. Australia commonly uses a 20 mL tablespoon, so the recipe’s origin matters.
- 1 US customary cup ≈ 236.588 mL.
- 1 US fluid ounce ≈ 29.5735 mL.
- 1 US customary tablespoon ≈ 14.7868 mL.
- 1 metric measuring teaspoon = 5 mL.
- Do not assume an imperial cup or fluid ounce matches the US version.
Choose the safest conversion path
For volume-to-volume conversions, first identify the regional unit, then use its defined factor. For mass-to-mass conversions, ounces and grams can be converted directly when ‘ounce’ means the ordinary avoirdupois ounce. For volume-to-mass conversions, use a gram weight supplied for that ingredient and preparation method by a reliable recipe or food-data source.
When scaling a recipe, convert first and scale second using unrounded values. For example, 1.5 US cups is about 354.882 mL; doubling the recipe gives about 709.765 mL before practical rounding. Rounding the one-cup factor too early can compound across a large batch.
Measure for repeatable results
Place a liquid measure on a level surface and read the meniscus at eye level. For small volumes, use the correct measuring spoon rather than tableware. For dry ingredients measured by volume, follow the recipe’s method—such as spoon-and-level or packed—because technique changes the amount.
A scale removes much of that variation and makes resizing easier. Tare the bowl between ingredients and keep the displayed precision realistic for the scale. A device that reads in whole grams cannot justify reporting hundredths of a gram.
- Keep mL for volume and g for mass; never swap the symbols.
- Check whether ‘oz’ means mass or ‘fl oz’ means fluid volume.
- Use the recipe author’s own gram equivalents when possible.
- For very small quantities, follow the original unit rather than forcing a coarse conversion.
Put this guide into practice
Use the volume converters for regional US units and the mass converters only when the recipe is already expressed by weight.
- US cups to millilitres: Convert using the US customary cup.
- US tablespoons to millilitres: Convert US customary spoon volume.
- US fluid ounces to millilitres: Keep fluid volume distinct from ounce mass.
- Grams to ounces: Convert an ingredient amount already measured by mass.
Sources and standards
The definitions and factors in this guide were checked against these primary standards and government references.