Since 3 teaspoons make 1 tablespoon, and 2 tablespoons make 1 fluid ounce, 1 ounce is equivalent to 6 teaspoons. Care must be taken to distinguish between measurements of weight and volume in this case, as dry ounces and liquid ounces measure weight and volume, respectively.
Since a teaspoon is a measure of volume, it cannot be directly converted to dry ounces, which measure weight. Confusion between the two units can result in radically different amounts of ingredients being added to recipes, depending on the density of the ingredient. Fluid ounces are also defined slightly differently in the United States and Great Britain. A fluid ounce of water in Great Britain weighs exactly 1 dry ounce, but in the United States 1 fluid ounce of water is somewhat more than a dry ounce in weight.