As a unit of measurement, a tablespoon is three times larger than a teaspoon. In the U.S., a tablespoon is equal to 0.5 fluid ounce, or 14.79 milliliters, while a teaspoon is equal to 0.17 fluid ounce, or 4.93 milliliters. In British Imperial measurements, a tablespoon is equal to 0.625 fluid ounce, or 17.76 milliliters, while a teaspoon is equal to 0.21 fluid ounce, or 5.92 milliliters.