What is the ratio of ml to teaspoon?

The ratio of millilitres to teaspoons depends on the ingredient being measured. For liquid ingredients, 1 teaspoon (tsp) is approximately equivalent to 5 millilitres (ml). However, for dry ingredients, the conversion may vary. For example, 1 tsp of flour is about 2.5 ml, while 1 tsp of baking powder is about 3 ml. It is important to check the specific ingredient and recipe instructions for accurate measurements.