Metric 5 mL, US 4.93 mL
The metric teaspoon is a clean 5 mL. The US customary teaspoon is 4.92892 mL — about 1.4% smaller, which never matters in the kitchen. So 10 mL is 2 metric teaspoons and 2.03 US teaspoons: the same two spoonfuls in practice.
Quick reference
| mL | Metric tsp | Practical |
|---|---|---|
| 2.5 | 0.5 | ½ tsp |
| 5 | 1.0 | 1 tsp |
| 10 | 2.0 | 2 tsp |
| 15 | 3.0 | 1 tbsp |
| 30 | 6.0 | 2 tbsp |
The ladder is regular: 1 US cup = 16 tablespoons = 48 teaspoons = 236.6 mL.
Where teaspoons trip people up
- Kitchen spoon ≠ measuring spoon — a spoon from the drawer runs 2 to 9 mL. A measuring teaspoon is exactly 5 mL, and for medicine you should use a mL-marked dispenser every time.
- tsp vs tbsp is a 3× gap — confusing a teaspoon with a tablespoon triples the dose. It is the classic error when giving children liquid medicine, which is why labels now list mL.
- Australian tablespoon is 20 mL — it holds 4 teaspoons, not the usual 3. An Australian recipe's "2 tablespoons" is 40 mL, not 30.
Common questions
How many milliliters are in a teaspoon?
A metric teaspoon is exactly 5 mL. A US customary teaspoon is 4.92892 mL, which rounds to 5 for everyday use. For cooking and medicine, treat 1 teaspoon as 5 mL.
What is the difference between a teaspoon and a tablespoon?
One tablespoon is 3 teaspoons, or 15 mL against 5 mL. Mixing them up is a threefold error, which is a common and dangerous mistake when dosing liquid medicine.
Can I use a kitchen teaspoon to measure medicine?
No. Everyday spoons from a drawer hold anywhere from 2 to 9 mL, enough to cause a two- to threefold dosing error. Use the marked oral syringe or dosing cup and read it in mL.
