US fluid ounces
A US fluid ounces (sometimes referred to simply as an ounce) is a unit of volume used in the United States to measure liquids. One US fluid ounce is about 0.0296 liters.
UK fluid ounces
A UK fluid ounce is about 28.41 milliliters, a little smaller than the US fluid ounce of about 29.57 milliliters. So 1 US fluid ounce is about 1.04 UK fluid ounces.