There are 16 ounces in every pound. The easiest way to do this conversion without a calculator is to divide the number of ounces by 16. Whatever the answer is is the number of pounds.
You need to multiply the amount of ounces by 0.06. for instance 20 ounces would be 1.2 ponds.to get a more precise value you can multiply the ounces by 0.0625.