A tablespoon, denoted as “tbsp.,” is a unit of volume often used in cooking recipes. The United States customary system defines that 1 tbsp. is equal to one-half of a liquid ounce. However, a powder, such as sugar or salt, is measured in ounces (oz.) as weight. To make an exact conversion of ounces to tablespoons, you need to know the density of the powder.
Divide the volume of 29.6 ml that corresponds to 1 oz. liquid by two to calculate the volume in 1 tbsp.; 1 tbsp. equals to 29.6 /2 = 14.8 ml.
Get the density of the powder from the table given in the Resource section; for example, the density of brown sugar is 721 kg per cubic meter.
Divide the density of powder by 1,000 to convert it to grams per milliliter. In this example, the density of brown sugar is 721 / 1,000 = 0.721 g/ml.
Multiply the density of the powder by the volume of 1 tbsp. to calculate the mass of the powder in 1 tbsp. In this example, 1 tbsp. of brown sugar equals to 14.8 x 0.721 = 10.67 g.
Divide the weight of 28.35 g (1 oz.) by the weight of the powder in 1 tbsp. to convert ounces to tablespoons. In this example, 1 oz. corresponds to 28.35 / 10.67 = 2.6 tbsp.
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Oxana Fox is a freelance writer specializing in medicine and treatment, computer software and hardware, digital photography and financial services. She graduated from Moscow Medical College in 1988 with formal training in pediatrics.