Teaspoons to mL Converter
Convert US teaspoons to milliliters for cooking, baking, and medicine dosing.
How It Works
Formula: tsp to mL = value × 4.92892159
Example: 1 tsp = 4.928922 mL
Note: 1 US teaspoon equals 4.9289 milliliters (1/6 of a fluid ounce), the standard in American cooking.
Common Uses
Quick Conversion Table
| tsp | mL |
|---|---|
| 0.5 | 2.4645 |
| 1 | 4.9289 |
| 2 | 9.8578 |
| 4 | 19.7157 |
| 8 | 39.4314 |
| 16 | 78.8627 |
| 32 | 157.7255 |
| 64 | 315.451 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.01 mL
Precision Guidance
For cooking, round to 1 decimal. For medicine, follow label instructions and do not round loosely.
Common Mistakes
The US teaspoon (4.93 mL) is often rounded to 5 mL, but precise recipes use 4.9289 mL.
Frequently Asked Questions
What is 1 teaspoon in mL?
1 US teaspoon equals 4.9289 milliliters (1 tsp = 1/6 fl oz = 4.92892159 mL).
How do I convert teaspoons to mL?
Multiply the teaspoon value by 4.9289. For example, 2 tsp × 4.9289 = 9.8578 mL.
Is a US teaspoon 5 mL?
The US teaspoon is 4.93 mL. Many medical dosing charts round to 5 mL for simplicity, but cooking uses 4.93 mL.
How many teaspoons in a tablespoon?
1 US tablespoon equals 3 US teaspoons.
Deep Dive Guide
Teaspoons to mL: Convert US Small Measures to Metric
Convert teaspoons to mL with the exact US formula (1 tsp = 4.92892 mL). Covers seasoning, baking, and dosing for everyday American cooking.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 US gallon (gal) = 3.785411784 litres (exact, 231 in³)
- EXACT1 US fluid ounce (fl oz) = 29.5735295625 mL (exact, 1/128 gal)
- EXACT1 US cup = 236.5882365 mL (exact, 8 fl oz)
- EXACT1 US pint (pt) = 473.176473 mL (exact, 16 fl oz)
- EXACT1 US quart (qt) = 946.352946 mL (exact, 32 fl oz)
- EXACT1 litre (L) = 1000 millilitres (definition)
Common Pitfalls & How to Avoid Them
US vs. Imperial (UK) cups
A US cup is 236.59 mL, but a UK/metric cup is 250 mL and an Imperial cup is ~284 mL. Recipes from different countries are not interchangeable drop-in.
Fluid ounce is volume, not mass
A US fl oz is 29.57 mL of volume. 1 fl oz of water ≈ 29.57 g, but 1 fl oz of honey or oil weighs more. Do not treat fluid ounces as grams.
Teaspoon/tablespoon sizes differ
1 US tbsp = 14.7868 mL; 1 US tsp = 4.92892 mL. Metric measuring spoons are 15 mL and 5 mL — close but not exact; for baking precision use weighed grams.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy