A US teaspoon is one third of a US tablespoon.
Teaspoons to Milliliters Converter — tsp to mL
Convert Teaspoon (tsp) to Milliliter (mL) using the exact conversion factor (1 teaspoon = 4.928921594 milliliter). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Teaspoons to Milliliters converter
Converter
Cooking Converter
Convert cooking volume and mass units used in recipes and nutrition workflows.
Context values
Some unit families need one extra value for a physically accurate result.
Milliliter is 0.001 liter units.
Result = input x 4.92892159e-6 / 1e-6.
Volume units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Teaspoons to Milliliters
Teaspoon and Milliliter both show up in recipes, and converting between them matters whenever a recipe from one country's cookbook needs to be followed with another country's measuring tools. Teaspoon is typically associated with united States (cooking and recipe measurement), while Milliliter is typically associated with standard small-volume unit worldwide.
Formula
milliliters = teaspoons × 4.92892159375
This factor comes from each unit's defined relationship to the category's base unit: 1 teaspoon equals 0.00000492892159375 base units, and 1 milliliter equals 0.000001 base units, so dividing one by the other gives the direct teaspoon-to-milliliter factor of 4.92892159375.
Simple example
1 tsp × 4.928921594 = 4.928921594 mL
1 teaspoon = 4.928921594 milliliters.
Real-world example
2 tsp × 4.928921594 = 9.857843188 mL
2 teaspoons = 9.857843188 milliliters.
Conversion table
| Teaspoon (tsp) | Milliliter (mL) |
|---|---|
| 0.25 tsp | 1.232230398 mL |
| 0.5 tsp | 2.464460797 mL |
| 1 tsp | 4.928921594 mL |
| 2 tsp | 9.857843188 mL |
| 4 tsp | 19.71568638 mL |
| 8 tsp | 39.43137275 mL |
Reverse conversion: Milliliter to Teaspoon
4.928921594 mL × 0.2028841362 = 1 tsp
4.928921594 milliliters = 1 teaspoons.
teaspoons = milliliters × 0.202884136211
For a page dedicated to this direction, see Milliliter to Teaspoon.
Teaspoon vs. Milliliter
| Aspect | Teaspoon | Milliliter |
|---|---|---|
| Family | US customary unit | SI derived (metric prefix) unit |
| Typical use | US recipe and cooking measurement for small quantities | Medicine dosing (worldwide, including in the US) |
| Where it's used | United States (cooking and recipe measurement) | Standard small-volume unit worldwide |
Understanding the Teaspoon
Teaspoon (tsp) measures volume. The US teaspoon is exactly 4.92892159375 milliliters — 1/3 of a US tablespoon and 1/48 of a US cup. It is classified as a US customary unit.
Where it's used: United States (cooking and recipe measurement)
Uses of the Teaspoon today
- US recipe and cooking measurement for small quantities
- Medication dosing instructions in the US
- Baking measurement alongside the tablespoon and cup
Understanding the Milliliter
Milliliter (mL) measures volume. A milliliter is one-thousandth of a liter, equal to one cubic centimeter. It is classified as a SI derived (metric prefix) unit.
Where it's used: Standard small-volume unit worldwide
Uses of the Milliliter today
- Medicine dosing (worldwide, including in the US)
- Cooking and recipe measurement outside the US
- Beverage and small-container labeling
History of the Milliliter
The milliliter follows directly from the liter via the 'milli-' SI prefix. It is notable as one of the few metric units in routine US use, since medicine dosing (syringes, liquid medication) is specified in milliliters even in the US.
Historical origin. Milliliter was not the invention of a single named person; it developed through the process described above.
Teaspoon — sources
- NIST Handbook 44, Appendix C — General tables of units including the US teaspoon definition.
Milliliter — sources
- BIPM SI Brochure — SI prefixes — Defines 'milli-' as the prefix for 10⁻³.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many milliliters are in 1 teaspoon?
1 teaspoon equals 4.928921594 milliliters, using the exact defined conversion factor rather than an estimate.
How do I convert teaspoon to milliliter?
Multiply the teaspoon value by 4.928921594. The converter above does this instantly to whatever precision you set.
How do I convert milliliter back to teaspoon?
Use the reverse factor: 1 milliliter equals 0.2028841362 teaspoons. You can also use the swap control in the converter above to flip the direction instantly.
What is a teaspoon?
Teaspoon (tsp) measures volume. The US teaspoon is exactly 4.92892159375 milliliters — 1/3 of a US tablespoon and 1/48 of a US cup. It is classified as a US customary unit.
What is a milliliter?
Milliliter (mL) measures volume. A milliliter is one-thousandth of a liter, equal to one cubic centimeter. It is classified as a SI derived (metric prefix) unit.
Is the teaspoon to milliliter conversion exact?
Yes. The US teaspoon is exactly 4.92892159375 milliliters — 1/3 of a US tablespoon and 1/48 of a US cup. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the teaspoon still used today?
United States (cooking and recipe measurement)