How this calculator works
The US customary teaspoon is one third of a US tablespoon, or 1/768 of the 231 cubic inch US gallon. That makes it exactly 4.92892159375 mL. The metric teaspoon used in Canadian cooking holds 5 mL, about 1.4 percent more. The metric-teaspoon comparison in the tables helps when a recipe and a measuring set use different definitions.
Formula
mL = tsp x 4.92892159375. tsp = mL / 4.92892159375. Three US teaspoons make one US tablespoon, and one US tablespoon is 14.78676478125 mL.
Worked example
1 tsp = 4.92892 mL. 0.5 tsp = 2.46446 mL. 3 tsp = 14.7868 mL. 0.25 tsp = 1.23223 mL. 1 metric teaspoon of 5 mL is 1.01442 US tsp. 48 tsp = 1 US cup.
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Frequently asked questions
Is a teaspoon 5 mL?
A metric teaspoon is rounded to 5 mL, but a US customary teaspoon is exactly 4.92892159375 mL. The US value is about 1.4 percent smaller, which is negligible for seasoning and noticeable in careful baking.
Does this work for a heaped teaspoon?
No. A heaped spoon has no fixed volume. Use a level measuring spoon for a repeatable volume, or weigh the ingredient if the recipe gives a mass.
How many teaspoons are in a cup?
One US cup is 48 US teaspoons, because a cup holds 16 tablespoons and each tablespoon is three teaspoons. That is 236.588 mL.
Why does the result differ from a metric recipe?
A metric recipe assumes 5 mL per teaspoon, while this page uses the exact US 4.92892159375 mL. For a single teaspoon the difference is under 0.1 mL; for a large batch it accumulates.