How Many mL in a Teaspoon? (US, UK, Metric Conversions)

You reach for a teaspoon to measure your medicine or a recipe ingredient, but is that little spoon delivering exactly what you expect? The short answer: it depends on where you live and what you’re measuring: in the US, a teaspoon holds 4.92892 mL, while the metric teaspoon is exactly 5 mL — a difference that rarely matters for cooking but can be critical for medication dosing.

US standard teaspoon: 4.92892 mL ·
Metric teaspoon: 5 mL ·
UK legal teaspoon: 5 mL ·
US tablespoon: 14.7868 mL ·
Metric tablespoon: 15 mL

Six key volume equivalents cover the most common confusion points:

Is 5 mL a teaspoon in the UK?

It depends on which teaspoon you mean. The UK legally defines the teaspoon as 5 mL for trade and nutrition labeling (UK National Physical Laboratory). However, the old UK imperial teaspoon is 5.92 mL — about 18% larger. The US customary teaspoon, by contrast, is exactly 4.92892 mL (NIST). For everyday cooking, the 0.07 mL difference between US and metric teaspoons is negligible, but the imperial teaspoon’s extra 0.92 mL can throw off a recipe.

US vs UK teaspoon sizes

• US customary: 4.92892 mL
• Metric (UK legal): 5 mL
• UK imperial: 5.92 mL

Why 5 mL is the metric standard

The metric system standardised the teaspoon to 5 mL for simplicity. Most countries now follow this, including the UK for nutrition labels and the EU. The US still uses its own customary system in most cookbooks.

The implication: regional recipes require checking which teaspoon definition they use, especially for older British cookbooks.

How much is 10 mL in teaspoons or tablespoons?

Ten milliliters is a common dose for liquid medicines and a frequent measurement in recipes. In metric, 10 mL equals exactly 2 teaspoons (at 5 mL each) and roughly ⅔ of a tablespoon (since a metric tablespoon is 15 mL). In US customary units, 10 mL is about 2.03 teaspoons and 0.68 tablespoons.

Converting 10 mL to teaspoons

• Metric: 10 mL ÷ 5 mL/tsp = 2 tsp
• US customary: 10 mL ÷ 4.92892 mL/tsp ≈ 2.03 tsp

Converting 10 mL to tablespoons

• Metric tablespoon (15 mL): 10 mL ÷ 15 mL ≈ 0.67 tbsp
• US tablespoon (14.7868 mL): 10 mL ÷ 14.7868 ≈ 0.68 tbsp
• Australian tablespoon (20 mL): 10 mL ÷ 20 mL = 0.5 tbsp

Differences between US and metric tablespoons

The US tablespoon is 14.7868 mL, while the metric tablespoon is 15 mL — a 1.4% difference. Australian tablespoons are larger at 20 mL. Always check which system your recipe uses.

The pattern: For most kitchen use, the 0.07 mL gap between US and metric teaspoons is irrelevant, but the 5 mL difference between metric and Australian tablespoons will noticeably alter a recipe.

Is a 5 mL Calpol syringe the same as a 5 mL spoon?

Both deliver the same volume — 5 mL — but they are not interchangeable for accuracy. An oral syringe, like those packaged with Calpol, has precise markings and a plunger that delivers the exact dose. A 5 mL medicine spoon (the type with a narrow cup) is also calibrated, but a typical kitchen teaspoon can hold anywhere from 2.5 mL to 7.3 mL (National Physical Laboratory video).

Why syringes are more accurate than spoons

The NHS advises using an oral syringe rather than a kitchen spoon for liquid medicines because household spoons vary wildly (NHS — How to use liquid medicines). The UK Medicines and Healthcare products Regulatory Agency (MHRA) also warns that dosing should use the device supplied with the medicine (MHRA guidance).

When to use a medicine spoon vs oral syringe

For children, an oral syringe is preferred for doses under 5 mL (Royal Children’s Hospital Melbourne). A 5 mL medicine spoon is acceptable for older children and adults who can swallow the entire dose in one go. Never use a kitchen teaspoon for medicine.

The catch: For liquid medicines, the dosing device supplied is always more reliable than any spoon, even a calibrated one.

Is 1 mL half a teaspoon?

No — half a teaspoon is 2.5 mL (metric) or about 2.46 mL (US). One milliliter is roughly one-fifth of a teaspoon (0.2 tsp).

Half teaspoon measurements

• ½ metric teaspoon = 2.5 mL
• ½ US teaspoon ≈ 2.46 mL
• ¼ teaspoon = 1.25 mL (metric)

Common milliliter fractions

• 1 mL ≈ 0.2 tsp (⅕ tsp)
• 2 mL ≈ 0.4 tsp
• 3 mL ≈ 0.6 tsp
• 5 mL = 1 tsp

What this means: For doses under 2.5 mL, a syringe is essential because even a half-teaspoon measure can be inaccurate.

How many ml in a teaspoon of water?

The volume is still about 5 mL, but the weight varies because different liquids have different densities. Water has a density of roughly 1 gram per milliliter, so 5 mL of water weighs about 5 grams. Milk is slightly denser (~1.03 g/mL), so 5 mL of milk weighs about 5.15 grams. Oil is less dense (~0.92 g/mL), so 5 mL of oil weighs about 4.6 grams.

Does water density affect volume?

No — density does not change the volume. A teaspoon of water, milk, or oil each occupies the same 5 mL space. But if your recipe is by weight, the mass differs.

Teaspoon measurements for milk, oil

For cooking, the volume difference between liquids is negligible. In medicine, always measure by volume, not weight — use the device provided.

The real variation across systems becomes clear when you line up the numbers side by side.

For quick reference, here’s how common units stack up against milliliters in both major systems.

The implication: Even when volumes are close, the cumulative error from multiple tablespoons in a recipe can shift the outcome, especially in baking.

How to measure a teaspoon accurately

1. Use the right tool. For cooking, use metal or plastic measuring spoons designed for standard sizes. For medicine, use an oral syringe or a calibrated 5 mL medicinal spoon (Mayo Clinic).
2. Level it off. Dry ingredients should be levelled with a straight edge. For liquids, fill to the brim without spilling.
3. Read at eye level. For liquid in a spoon, the meniscus should be at the rim. For syringes, read the plunger ring — not the liquid meniscus.
4. Check the unit. Some recipes use “tsp” for teaspoon and “tbsp” for tablespoon. Don’t confuse them.
5. When in doubt, convert to mL. Use the numbers in this guide to convert any teaspoon measurement to milliliters.

The pattern: Consistent tool selection and proper technique eliminate most measurement errors.

“The size of teaspoons ranges from about 2.5 to 7.3 mL (0.088 to 0.257 imp fl oz; 0.085 to 0.247 US fl oz).”

— Wikipedia, “Teaspoon” article

“A kitchen teaspoon is not the same as a 5 mL spoon and should not be used to measure medicine.”

— NHS (How to use liquid medicines)

“Use the dosing device that comes with the medicine because kitchen spoons are not accurate.”

— Mayo Clinic (Medicine safety: Using the right dose)

For home cooks, the difference between 4.93 mL and 5 mL rarely alters a dish. But for parents measuring children’s medicine or for anyone following an old British recipe, the variation matters. The safe rule: for cooking, round to 5 mL; for medicine, use the supplied syringe or a calibrated 5 mL spoon — never a kitchen teaspoon. A mismatched teaspoon can mean the difference between a perfect cake and a dosing error.

For larger volumes, understanding the tablespoon to milliliters conversion can help when scaling recipes up or down.

Frequently asked questions