# How do I convert teaspoons to ml?

Converts teaspoons (tsp) to milliliters (mL) and back, with the exact unit definitions.

- Page: https://www.acalculator.org/convert/teaspoons-to-ml
- JSON spec: https://www.acalculator.org/convert/teaspoons-to-ml.json
- Version: 388265b3c203

## Default answer

Example with the default inputs (Teaspoons (tsp) 1): 1 tsp = 4.928922 mL.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| value | Teaspoons (tsp) | The amount in teaspoons to convert. |
| result | Milliliters (mL) | The same amount in milliliters. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| value | Teaspoons (tsp) | The amount in teaspoons to convert. |
| result | Milliliters (mL) | The amount in milliliters. |

## Method

mL = tsp × 4.92892159375

## Assumptions

- 1 teaspoon = 4.92892159375 milliliters, from the exact definitions in NIST SP 811.
- Cups, ounces, tablespoons, teaspoons, pints, quarts, and gallons are US customary units: 1 US cup is 8 US fluid ounces.
- Exact on the typed decimals: at most 6 decimal places (6 significant digits below 0.0001), rounded half up; an answer of 1 billion or more shows at most 15 significant digits.

## Worked examples

1. value = 1 gives result = 4.928922. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.
2. value = 3 gives result = 14.786765. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.
3. result = 14.786765 gives value = 3. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.

## FAQ

### How many milliliters are in a teaspoon?

1 teaspoon is 4.928922 milliliters, from the exact unit definitions (NIST SP 811).

### How do I convert teaspoons to ml?

Multiply by 4.928922: mL = tsp × 4.92892159375. For example, 1 tsp × 4.928922 = 4.928922 mL.

### How do I convert ml back to teaspoons?

Multiply by 0.202884, or type the milliliters into the second box and the converter works it out. 1 milliliter is 0.202884 teaspoons.

### Is a teaspoon 5 mL?

A US teaspoon is 4.928922 mL. Metric measuring spoons hold 5 mL, and NIST's metric kitchen guide counts a teaspoon as 5 mL, 1.4% more.

### How is a US teaspoon defined?

As 1/3 tablespoon or 1/6 US fluid ounce (NIST). A US fluid ounce is 1/128 of the US gallon of 3.785411784 L, so 1 tsp = 3,785.411784 mL ÷ 768 = 4.92892159375 mL.

### How many mL are in 3 teaspoons?

14.786765 mL, which is 1 US tablespoon.

## Sources

- NIST Office of Weights and Measures, Metric Household: 1 teaspoon = 1/3 tablespoon = 1/6 fluid ounce, 1 tablespoon = 1/2 fluid ounce, 1 cup = 8 fluid ounces (exact), retrieved 2026-10-18. https://www.nist.gov/pml/owm/metric-household
- NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B.8: Factors for Units Listed Alphabetically (bold factors are exact), retrieved 2026-10-18. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8
- NIST Office of Weights and Measures, Metric Kitchen: Cooking Measurement Equivalencies (approximate: 1 teaspoon = 5 mL, 1 tablespoon = 15 mL), retrieved 2026-10-18. https://www.nist.gov/pml/owm/metric-si/metric-kitchen/metric-kitchen-cooking-measurement-equivalencies