Tablespoon to mL — 15 mL, and When Not to Use It

A US tablespoon is 15 mL and a teaspoon is 5 mL. Those are not approximations rounded off for convenience: FDA labeling rules fix them at exactly those values, along with 240 mL for a cup and 30 mL for a fluid ounce. Pick a measure and a quantity:

The kitchen chart

Measure	Milliliters
Teaspoon (tsp)	5 mL
Tablespoon (tbsp)	15 mL
Fluid ounce (fl oz)	30 mL
Quarter cup	60 mL
Third of a cup	80 mL
Half cup	120 mL
Cup	240 mL

The relationships are clean by design: three teaspoons to a tablespoon, two tablespoons to a fluid ounce, sixteen tablespoons to a cup. This is the labeling convention, and it is what a nutrition panel means when it says a serving is one tablespoon.

There is a small wrinkle worth knowing if you are precise about it. The legal US fluid ounce is 29.5735 mL and the US customary cup is 236.6 mL — the 30 and 240 above are the rounded values that the food labeling rule adopted so the arithmetic works out evenly. For cooking the difference is nothing. Where the bottle scale is printed in ounces, as with oz to mL for baby formula, the 29.57 figure is the one that matters.

The same word, three different volumes

A tablespoon is a national convention, not a physical constant, and a recipe that travelled will carry its home country’s version:

Country	Tablespoon
United States	15 mL
United Kingdom	15 mL
Canada	15 mL
Australia and New Zealand	20 mL

Australia’s 20 mL spoon is the outlier, and it is a third bigger. Four tablespoons of an Australian recipe is 80 mL where an American cook would produce 60 mL. In baking that shows; in anything salted or spiced heavily it shows more.

Why medicine dropped the spoon entirely

The tablespoon has one place where its conversion is not merely inconvenient but dangerous, and that is on a medicine label. The American Academy of Pediatrics states the position bluntly in its policy on liquid dosing: milliliter-based dosing should be used exclusively when prescribing and administering liquid medications, and teaspoon- and tablespoon-based dosing should not be used. Devices allowing precise dosing — syringes marked in metric units — should be supplied with the medicine and used instead of household spoons.

Two reasons sit behind that.

The words look alike. “tsp” and “tbsp” differ by one letter, and confusing them gives three times the intended dose. It is one of the most common liquid dosing errors in the US.

Household spoons are not measuring instruments. A drawer full of teaspoons will span a substantial range of actual volumes, none of them 5 mL by intention. FDA-approved labels for oral solutions carry the warning directly: a household teaspoon is not an accurate measuring device and could lead to overdosage.

The practical rule is short. Kitchen measures for food; the syringe or dosing cup that came in the box, read in mL, for medicine. Never migrate a dose from one to the other.

For medicines dosed by drop rather than by spoon — where the unit is even less standardised — see drops to mL. And for the weight most pediatric doses are calculated from, pounds to kg.

This content is informational. Follow the label and the advice of a pharmacist or physician for any medication dose.