How this calculator works
Enter an amount and pick the unit it’s currently in and the unit you want to convert it to. The calculator converts your amount into milliliters first, using NIST’s exact US customary fluid measure constants, then converts that milliliters figure into your chosen target unit. Every conversion, no matter which two units you pick, runs through this same milliliters pivot.
These are US customary units only: cups, tablespoons, teaspoons, and fluid ounces as defined for US recipes. The metric cup used in Australia and some other countries (a flat 250 mL) and the UK/Imperial definitions of cup, tablespoon, and teaspoon are different units with different sizes, and they are out of scope for this calculator. If your recipe comes from a UK or Australian source, don’t treat this tool’s cup, tablespoon, or teaspoon figures as equivalent to yours.
The formula
mL_amount = amount x mL_per_unit[fromUnit] result = mL_amount / mL_per_unit[toUnit] mL_per_unit: cup = 236.5882365 tbsp = 14.78676478125 tsp = 4.92892159375 fl_oz = 29.5735295625 mL = 1 L = 1000
Worked example
Converting 2 cups to milliliters:
- Milliliters pivot: 2 x 236.5882365 = 473.176473 mL
- Rounded to the nearest whole milliliter: 473 mL
Frequently asked questions (FAQ)
How many milliliters are in a US cup?
Exactly 236.5882365 milliliters. This is the US customary fluid measure defined in NIST Handbook 44, Appendix C, and it is the constant this calculator uses for every cup conversion, whether you're converting into mL, liters, or another US measure.
Is a US cup the same as a metric cup?
No. A US customary cup is 236.5882365 mL, while a metric cup, used in Australia and some other countries, is a flat 250 mL. This calculator only handles US customary units, so metric-cup recipes will need a different conversion.
How many teaspoons are in a tablespoon?
Exactly 3 US teaspoons make 1 US tablespoon. Because both units convert through the same milliliters pivot (14.78676478125 mL per tablespoon, 4.92892159375 mL per teaspoon), that ratio comes out clean with no rounding error introduced by the conversion.
Why does this calculator use so many decimal places in its constants?
The US customary units of volume are defined in NIST Handbook 44 to that level of precision. Rounding the constants themselves would introduce small errors that compound when you convert back and forth, so this tool keeps them exact and only rounds the final displayed answer.
Can I use this calculator for UK or Australian recipes?
Not directly. UK and Australian tablespoons, teaspoons, and cups use different volumes than the US customary units this calculator is built on, most notably a 250 mL metric cup and a 15 mL Australian/UK tablespoon. Using this tool's values for those recipes will give the wrong amount.
Why do my converted measurements sometimes look like odd decimals?
Because cups, tablespoons, teaspoons, and fluid ounces don't divide evenly into milliliters or liters. The calculator rounds the final result to the nearest whole milliliter, or to 2 decimal places for every other unit, so a conversion can land on a figure like 6.34 cups instead of a round number.