Which tablespoon? There are three
The answer depends on where the recipe is from. A US tablespoon is 14.79 mL, a metric one is 15 mL, and an Australian one is 20 mL. For cooking, treating a tablespoon as 15 mL is close enough everywhere except Australia.
US and metric spoons are almost identical, but the Australian tablespoon is a third larger — so "3 tbsp" of an Australian recipe holds noticeably more.
The conversion
In your head, divide by 15. That is exact for metric and off by only 1.4% for US, which is fine for a kitchen. Two other pegs help: 5 mL is 1 teaspoon, and 250 mL is roughly 1 cup or 16 tablespoons.
Common amounts
| mL | US tbsp | Metric tbsp | AU tbsp |
|---|---|---|---|
| 5 | 0.34 | 0.33 | 0.25 |
| 15 | 1.01 | 1.00 | 0.75 |
| 30 | 2.03 | 2.00 | 1.50 |
| 50 | 3.38 | 3.33 | 2.50 |
| 100 | 6.76 | 6.67 | 5.00 |
| 250 | 16.91 | 16.67 | 12.50 |
| 500 | 33.81 | 33.33 | 25.00 |
Volume is not weight: 15 mL of water weighs about 15 g, but 15 mL of honey is ~21 g and 15 mL of flour only ~8 g.
Two errors worth avoiding
- Tablespoon vs teaspoon. A tablespoon is 3 teaspoons. Mixing them up triples or thirds the amount — with medicine that can be dangerous.
- Assuming 15 mL for an Australian recipe. The AU tablespoon is 20 mL, so 100 mL is 5 AU tbsp, not 6.67. Check where the recipe comes from before you scale it.
Common questions
How many tablespoons is 15 mL?
One metric tablespoon exactly. In the US system it is 15 divided by 14.79, which is 1.01 tablespoons, so still one level tablespoon in practice.
How many tablespoons is 100 mL?
About 6.76 US tablespoons, or 6.67 metric. If the recipe is Australian, the tablespoon is 20 mL, so 100 mL is exactly 5.
Why does the FDA want medicine dosed in mL, not tablespoons?
Kitchen spoons are not standardized; drawer spoons range from about 6 to 29 mL. Measuring medicine with them causes frequent dosing errors, so labels and dosing cups use mL instead.
