2.5 mL to US teaspoons.
2.5 mL = 0.51 US teaspoons. On US food labels, 1 tsp means exactly 5 mL, so 2.5 mL is 0.5 label teaspoons.
What 2.5 mL means
- At the 5 mL food-label size, 2.5 mL is half a teaspoon (½ tsp).
- This volume is 0.17 US tablespoons and 0.085 US fluid ounces.
- A ½ tsp mark and a 2.5 mL mark are the same dose on a label.
- A US customary teaspoon is exactly 4.92892159375 mL. US food labels round it to 5 mL, a difference of 1.4 %.
Measuring a 2.5 mL dose
- Dose liquid medicine in mL only. The American Academy of Pediatrics recommends doses to the nearest 0.1, 0.5 or 1 mL, measured with an oral syringe.
- Draw the syringe to the 2.5 mL line. Use the device that comes with the medicine, or one from a pharmacy.
- In a study of parents of young children, those using teaspoon or tablespoon units had about twice the odds of a dosing error as those using mL only.
- The FDA and US pharmacy standards bodies recommend mL as the only unit on prescription labels for oral liquids.
How to convert
- Divide by 4.92892159375 (the exact mL in one US teaspoon): 2.5 ÷ 4.9289 = 0.51 US tsp.
- For the food-label teaspoon, divide by 5: 2.5 ÷ 5 = 0.5 tsp.
To convert the other way, use the US teaspoons to milliliters converter.
Nearby values
| mL | US tsp (4.93 mL) | Label tsp (5 mL) | US tbsp |
|---|---|---|---|
| 0.5 mL | 0.10 | 0.10 | 0.03 |
| 1 mL | 0.20 | 0.20 | 0.07 |
| 1.5 mL | 0.30 | 0.30 | 0.10 |
| 2 mL | 0.41 | 0.40 | 0.14 |
| 2.5 mL | 0.51 | 0.50 | 0.17 |
| 3 mL | 0.61 | 0.60 | 0.20 |
| 3.5 mL | 0.71 | 0.70 | 0.24 |
| 4 mL | 0.81 | 0.80 | 0.27 |
| 4.5 mL | 0.91 | 0.90 | 0.30 |
| 5 mL | 1.01 | 1.00 | 0.34 |
Questions people ask
Is 2.5 mL a teaspoon or a tablespoon?
At the 5 mL label size, 2.5 mL is half a teaspoon (½ tsp). One tablespoon is 15 mL, or 3 teaspoons.
Can I measure a 2.5 mL dose of medicine with a kitchen spoon?
For medicine, use the cup, syringe or dropper that comes with it. The FDA says a kitchen spoon could hold the wrong amount. Use an oral syringe or a dosing cup marked in mL, filled to the 2.5 mL line.
Sources: NIST Handbook 44, Appendix C (US gallon, quart, pint, cup, fluid ounce, tablespoon and teaspoon); 21 CFR 101.9(b)(5)(viii) (FDA nutrition labeling: 1 tsp = 5 mL, 1 tbsp = 15 mL); FDA Consumer Update: Ten Tips to Prevent an Accidental Overdose; FDA-hosted guidance on mL-only dosing for oral liquid medicines; American Academy of Pediatrics, Metric Units and the Preferred Dosing of Orally Administered Liquid Medications, Pediatrics 2015;135(4):784–787; Yin HS et al., Unit of measurement used and parent medication dosing errors, Pediatrics 2014;134(2):e354–e361.
Sources & verification
Unit definitions used by this converter:
- milliliter: 1 mL = 0.001 L, exact — BIPM SI Brochure, 9th ed.
- teaspoon (US): 1 tsp (US) = 0.00492892159375 L, exact (tsp = 1/3 tbsp) — NIST Handbook 44 (2026), Appendix C