How Many ML Are in a Teaspoon?
The Formula
Common Teaspoons to Milliliters Values
| Teaspoons | Milliliters | Fraction |
|---|---|---|
| 0.25 | 1.23 | 1¼ |
| 0.5 | 2.46 | 2½ |
| 0.75 | 3.70 | 3⅔ |
| 1 | 4.93 | 4⅞ |
| 1.5 | 7.39 | 7⅜ |
| 2 | 9.86 | 9⅞ |
| 3 | 14.79 | 14¾ |
| 4 | 19.72 | 19¾ |
| 5 | 24.65 | 24⅝ |
| 8 | 39.43 | 39⅜ |
| 10 | 49.29 | 49¼ |
| 12 | 59.15 | 59⅛ |
A Worked Example
A recipe calls for 3 teaspoons of vanilla extract, which happens to equal 1 tablespoon. Multiply 3 by 4.929 to get about 14.8ml — confirming the teaspoon-to-tablespoon relationship holds at the milliliter level too.
When This Conversion Matters
A US teaspoon is 4.93ml, often rounded to 5ml on measuring spoons and international recipes.
This small-volume conversion matters most for spices, extracts, and leavening agents.
Cough medicine and other over-the-counter liquid dosing frequently uses this conversion as a safety reference, since the small difference between a US and metric teaspoon rarely matters but calibrated dosing devices remain the safer choice.
Home baristas and coffee enthusiasts calculating precise flavor additions, like a drop of vanilla or a pinch of salt in cold brew, often relate their recipe's milliliter specification back to a teaspoon for practical measuring.
Veterinary medicine dosing instructions for pet owners sometimes reference this conversion when a prescription is written in milliliters but an owner only has household teaspoons available for a rough estimate before getting a proper dosing syringe.
Standards and Sources
The US teaspoon is fixed at 4.929 milliliters under NIST measurement standards, exactly 1/3 of the US tablespoon and 1/48 of the US cup.
The metric teaspoon (5ml), used in pharmacology and many international contexts, is about 1.4% larger than the US teaspoon — a gap small enough that most recipes treat the two as interchangeable.
Health authorities including the FDA specifically caution against using an ordinary kitchen teaspoon for medicine dosing, since real-world teaspoon volumes vary more than the standardized 4.929ml or 5ml figures suggest.
The FDA's 2015 guidance on over-the-counter liquid medication specifically recommended manufacturers phase out spoon-based dosing instructions in favor of milliliter-marked devices, citing measurement inconsistency as a safety concern.
Where This Unit Comes From
Like the tablespoon, the teaspoon's non-round 4.929ml figure comes from being defined as a fraction of the US cup rather than as an independent, round metric unit like the 5ml pharmacological teaspoon.
Where This Shows Up
Cough medicine and other over-the-counter liquid dosing frequently uses this conversion as a safety reference, since the small difference between a US and metric teaspoon rarely matters but calibrated dosing devices remain the safer choice.
Home baristas and coffee enthusiasts calculating precise flavor additions, like a drop of vanilla or a pinch of salt in cold brew, often relate their recipe's milliliter specification back to a teaspoon for practical measuring.
Homemade tincture dosing instructions, often written by herbalists in milliliters for precision, are sometimes informally translated into teaspoons for users without a calibrated dropper on hand.
Home aromatherapy diffuser blends, which specify drop and milliliter ratios precisely for safety, occasionally require this conversion when a recipe card lists a teaspoon-based carrier oil amount instead.
Common Mistakes
- Using a kitchen teaspoon instead of a calibrated dosing device for medicine, which health authorities specifically caution against.
- Treating the US (4.929ml) and metric (5ml) teaspoon as identical when the small difference actually matters, such as in pharmaceutical contexts.
- Overfilling a teaspoon with a thick ingredient like honey or syrup, adding unpredictable extra volume beyond the standard figure.
- Using a spoon from a mismatched flatware set as a stand-in for a calibrated measuring teaspoon, since decorative spoons are rarely standardized.
US Teaspoon vs Metric Teaspoon
| US Teaspoon | Metric Teaspoon | |
|---|---|---|
| Volume | 4.929 ml | 5 ml |
| Fraction of tablespoon | 1/3 | 1/3 (approx.) |
| Common context | US recipes | Pharmacology, intl. recipes |
Related Converters
Frequently Asked Questions
How many ml are in a teaspoon?+
4.93ml, close to the rounded 5ml figure used on most measuring spoons.
How many ml are in 2 teaspoons?+
About 9.86ml.
Is a metric teaspoon different?+
Yes, it's defined as exactly 5ml.
Is the difference between 4.93ml and 5ml significant in cooking?+
No, it's under 1.5% and falls well within normal kitchen measuring tolerance for nearly every recipe.
How many ml are in half a teaspoon?+
About 2.46ml.
Is a dosing syringe more accurate than a teaspoon?+
Yes, significantly — a calibrated syringe measures to a precise ml marking, while a household teaspoon's actual volume can vary noticeably between sets.
Is a coffee spoon the same as a teaspoon?+
No, a coffee or demitasse spoon typically holds less than a standard teaspoon and shouldn't be used as a substitute for precise measuring.