The factor depends on which teaspoon you mean
A US teaspoon is 4.92892 mL, defined as one sixth of a US fluid ounce. The metric teaspoon is a round 5 mL, and the UK imperial teaspoon is 5.92 mL. For everyday cooking, treat a teaspoon as 5 mL.
The US and metric teaspoons are almost identical; the UK imperial teaspoon is about 20 percent larger.
Quick reference
| Teaspoons | US mL | Metric mL | Note |
|---|---|---|---|
| ¼ tsp | 1.23 | 1.25 | pinch |
| ½ tsp | 2.46 | 2.5 | — |
| 1 tsp | 4.93 | 5.0 | — |
| 1½ tsp | 7.39 | 7.5 | — |
| 2 tsp | 9.86 | 10.0 | common child dose |
| 3 tsp | 14.79 | 15.0 | 1 tablespoon |
| 48 tsp | 236.6 | 240.0 | 1 cup |
The relationship 3 teaspoons = 1 tablespoon = 15 mL holds in the US, UK and metric systems.
Two things that trip people up
- Australian tablespoons are 20 mL. Australia is the one place a tablespoon equals 4 teaspoons, not 3. An Australian recipe calling for 2 tablespoons wants 40 mL, so a standard 15 mL spoon leaves you 25 percent short.
- Never dose medicine with a kitchen spoon. Drawer spoons range from 2 to 9 mL. Mixing up teaspoon and tablespoon triples the dose. Use the syringe or cup marked in mL that comes with the medicine.
Common questions
How many mL are in a teaspoon?
A metric teaspoon is exactly 5 mL. A US teaspoon is 4.93 mL and a UK imperial teaspoon is 5.92 mL. For cooking the US and metric figures are close enough to treat both as 5 mL.
Is a teaspoon 5 mL or 4.9 mL?
Both, depending on the system. The metric teaspoon is defined as exactly 5 mL, while the US customary teaspoon is 4.92892 mL (one sixth of a US fluid ounce). The 1.4 percent gap does not matter in cooking, and medicine labels use 5 mL.
Can I use a kitchen teaspoon to measure medicine?
No. Ordinary spoons from a drawer hold anywhere from 2 to 9 mL, which can cause a two to four times dosing error. The FDA and pediatricians recommend a calibrated oral syringe or dosing cup marked in mL.
