Teaspoon (tsp)

The teaspoon is the smallest standard measure in US recipes, used for salt, baking soda, spices and vanilla. It is a tiny slice of the customary system: 6 teaspoons make a fluid ounce, and 48 teaspoons fill a cup.

NIST lists the measuring teaspoon next to the cup and tablespoon, but calls the teaspoon and tablespoon "imprecise units" and rounds their metric equivalents to the nearest milliliter (NIST Handbook 44, Appendix C). A footnote there says a number of dictionaries give the teaspoon as one fluid dram, while NIST found a larger figure matches real measuring and silver teaspoons better.

Dip the spoon into the dry ingredient, lift it out heaped, and sweep the back of a knife across the top. Recipes mean a level spoon unless they say heaping or rounded.

For liquids, hold the spoon flat over a small bowl and fill it to the brim. Spoon sets usually run from 1/4 tsp to 1 tbsp, and many add 1/8 tsp.

A spoon from the cutlery drawer is a poor stand-in, since table spoons vary in size and shape. Pinch and dash have no official size at all, so treat them as a matter of taste.

Yes. For Nutrition Facts panels, US rules count a teaspoon as 5 ml, the same size as the metric teaspoon in the table above, and allow teaspoon serving sizes only in set steps from 1/8 tsp to 2 tsp (21 CFR 101.9).

The gap between US and metric spoons is small: one metric teaspoon equals 1.014 teaspoons in US measure. For baking soda or salt, that difference is far smaller than the one between a level and a heaping spoon.