A tablespoon (tbsp) is a unit of volume used mainly in cooking. In the US customary system it equals 3 teaspoons, half a fluid ounce and one sixteenth of a US cup. It is a measure of volume, not the size of a dining spoon, which varies between cutlery sets.
Conversion
1 tbsp = 3 tsp = 1/2 fl oz = 1/16 cup
mL = tbsp × 14.78676
NIST's conversion factors give 14.78676 mL per tablespoon. For US nutrition labeling, 21 CFR 101.9(b)(5)(viii) rounds it to 15 mL.
Example
Three tablespoons of oil are 3 × 3 = 9 teaspoons, 1.5 fl oz, 3/16 cup and 3 × 14.78676 = 44.36 mL. Eight tablespoons make half a cup.
The tablespoons in a cup guide has the chart for every fraction, how many teaspoons in a tablespoon covers the small step, and the converters tablespoons to cups and tablespoons to ml handle other values.
Common mistakes
Swapping tablespoon and teaspoon abbreviations triples or divides an amount by three. Heaped spoons also hold more than level ones, so recipes assume a level spoon.