I guess really it would depend on the density of the product that you have in your tablespoon (e.g. - a tablespoon of peanut butter won't weigh the same as a tablespoon of baking powder), but as an indication, 1 tablespoon is about 14.2 to 14.3 grams.
You should just weigh the mass of what you have in the tablespoon to find out.
20 grams equals how many tbsp