A dry ounce is a measurement of weight, not volume. One dry ounce is equivalent to 28.3495231 grams, or about 0.960769979 ounces. When measuring ingredients for baking and cooking, it's important to pay attention to the difference between a dry ounce and a liquid ounce – they're not the same!
When it comes to converting an ounce of dry ingredients into tablespoons (or any other unit of measure), it depends entirely on what type of ingredient you're measuring. For example, one dry ounce of flour weighs approximately 3 tablespoons; however one dry ounce of oats would be closer to 2/3 cup or 4 1/2 tablespoons when measured out.