Three Spoons, One Name: US, UK, and AU Tablespoons
| Country | mL | Defined as | % vs US |
|---|---|---|---|
| United States | 14.787 mL | 1/16 US cup = 1/256 US gallon | —/td> |
| United Kingdom / EU | 15 mL | Rounded metric value | +1.4% |
| Australia | 20 mL | 4 tsp × 5 mL (metric rounding) | +35.3% |
The US tablespoon is the odd one: 14.7868 mL —not 15. Why? Because it's derived, not rounded. The US fluid ounce = 1/128 gallon = 29.57353 mL. A tablespoon is 1/2 fluid ounce = 14.7868 mL. It was never rounded to a metric value because the US never metricated its kitchen measurements. The UK rounded to 15 mL in the 1970s. Australia chose 20 mL —intentionally larger, so that 4 Australian teaspoons (each 5 mL) made 1 Australian tablespoon. The choice was aesthetic, not culinary: a metric tablespoon should be a clean multiple of a metric teaspoon, and 4 teaspoons of 5 mL each = 20 mL. The US tablespoon's relationship to the teaspoon (1 US tbsp = 3 US tsp, each 4.9289 mL) was preserved because the US didn't change anything. Australia's choice broke the 3:1 ratio and replaced it with a 4:1 ratio, on the grounds that a tablespoon that equals exactly 4 teaspoons was easier to teach in primary school. The metrication board was staffed by educators, not chefs. Chefs would have chosen differently. Australian cookbook authors have been compensating for the 35% tablespoon ever since.
When a Tablespoon Is Not a Tablespoon: The Medicine Cabinet
The most dangerous tablespoon conversion is the one performed at the bathroom sink at 3 AM. A parent with a sick child, a bottle of cough syrup that says "take 1 tablespoon (15 mL)," and a kitchen drawer full of spoons. The parent grabs a spoon —not the measuring spoon in the baking drawer, but the flatware spoon next to the forks. Flatware tablespoons vary from 10 mL (old-fashioned slim soup spoons) to 25 mL (modern oversized serving spoons). The dose the child receives varies by up to 2.5× depending on which spoon the parent grabbed. The FDA has warned against kitchen-spoon dosing since 1988. The American Academy of Pediatrics endorsed oral syringes in 2010. Yet a 2016 study in Pediatrics found that 40% of parents still use kitchen spoons for children's liquid medication —and the dosing error averages 20% in either direction. A child who should receive 15 mL of paracetamol receives 12 mL (sub-therapeutic) or 18 mL (approaching toxicity) because the spoon is wrong. The metric system solved this: medications are prescribed in mL, dispensed with mL-marked dosing devices, and administered without reference to spoons. The kitchen spoon is a cooking tool. It should never touch medicine. For the reverse conversion —when a medicine syringe reads in mL but the old doctor's instructions say "one teaspoon" —see mL to teaspoons and teaspoons to mL.
mL = tbsp (US) × 14.78676478 | mL = tbsp (UK/EU) × 15 | mL = tbsp (AU) × 20
Common Tablespoons to mL
| US tbsp | mL | UK/EU mL | AU mL | Kitchen context |
|---|---|---|---|---|
| 1/2 tbsp | 7.39 mL | 7.5 mL | 10 mL | 1.5 teaspoons. Vanilla extract for a small batch of cookies. |
| 1 tbsp | 14.79 mL | 15 mL | 20 mL | Olive oil to sauté an onion. Soy sauce for a stir-fry. The foundational spoon measure. |
| 2 tbsp | 29.57 mL | 30 mL | 40 mL | One US fluid ounce. A standard coffee scoop. Salad dressing for one serving. |
| 4 tbsp | 59.15 mL | 60 mL | 80 mL | 1/4 US cup. A quarter-stick of butter (half of a half-stick). |
| 8 tbsp | 118.3 mL | 120 mL | 160 mL | 1/2 US cup. One stick of butter. The difference between the US and Australian 8-tbsp measures is 41.7 mL —more than 2 US tablespoons. |
| 16 tbsp | 236.6 mL | 240 mL | 320 mL | 1 US cup. The Australian 16-tbsp is 320 mL —which is not one metric cup (250 mL). The Australian tablespoon-to-cup math breaks at the cup level because the cup was rounded differently from the tablespoon. |
Frequently Asked Questions
How do I know which tablespoon a recipe uses?
Country of origin is the most reliable clue. US recipe →US tablespoon (14.8 mL). UK recipe published after 1980 →15 mL. Australian recipe →20 mL. Canadian recipe →15 mL (Canada uses the metric tablespoon). New Zealand →15 mL. South African →15 mL. If the recipe is from a website with no country marker: check the other units. If the recipe also lists flour in cups →likely US (14.8 mL). If the recipe lists flour in grams and liquids in mL →likely UK/EU/AU (15 or 20 mL). If the recipe mentions "desiccated coconut" and "bicarbonate of soda" →likely Australian (20 mL). If uncertain, look at the butter quantity: 1 Australian tablespoon of butter ≈20 g. 1 US tablespoon ≈14 g. If the recipe calls for "4 tbsp butter" and a separate weight is given (e.g., "60 g butter"), the tablespoon is 15 mL (UK). If the weight says "80 g," it's Australian. The butter tells the truth.
Is the 1.4% difference between US (14.79 mL) and UK (15 mL) tablespoons noticeable?
Not in a single tablespoon. The difference is 0.21 mL —about 4 drops of water. In a recipe with 2 tbsp of vanilla extract, the difference is 0.42 mL —8 drops. No human palate can detect 8 drops of vanilla in a batch of 24 cookies. The problem emerges when the tablespoon is used as a scaling unit: a commercial bakery recipe calling for "48 tbsp of salt" means 710 mL (US) or 720 mL (UK) —a 10 mL difference, roughly 2 teaspoons of salt in a batch of 500 bagels. At industrial scale, the 1.4% matters. At home, it does not. The 1.4% US/UK tablespoon gap is the least consequential unit conversion problem in the kitchen. For scaling and precision, see the Volume & Cooking Guide.
Engineering Context
The US tablespoon is 1/16 US cup = 1/256 US gallon = 0.90234375 cubic inches = 14.78676478 cm³. It is a legally defined unit in the US (FDA 21 CFR 101.9 for nutrition labeling), though the FDA rounds it to 15 mL on nutrition facts panels. The Australian tablespoon (20 mL) is defined in Australian Standard AS 1000-1979 and is not a legal unit outside Australia. For pharmaceutical manufacturing, the tablespoon has been deprecated: the USP (United States Pharmacopeia) recommends specifying all liquid doses in mL, and FDA guidance since 2009 requires OTC liquid medication labels to include a calibrated dosing device marked in mL. The engineering lesson of the tablespoon is that a unit defined by a ratio to a larger unit (1/16 cup) produces an awkward decimal when that larger unit is redefined in metric —and rounding that decimal to a clean metric number creates a new unit that shares a name with the old one but means something different. The tablespoon problem has no fix. There are too many cookbooks, too many measuring spoon sets, and too many grandmothers' recipe cards written in three different tablespoons across three different countries. See also: mL to tablespoons, teaspoons to mL, mL to teaspoons, cups to mL, and the Volume Guide.