Milk weighs approx. 3% more than water. (That's regular cow's milk)
So, 1 fluid ounce would be 1.03 ounces by weight, hardly any difference.
But 1 US gallon (128 fl oz) would be 131.84 ounces by weight.
For cooking, the volumes of milk you would typically be dealing with are small enough that you can just pretend 1 fluid ounce equals 1 ounce.
1 oz
Take one ounce of breast milk by volume and weigh it -- what is the weight?
It weighs from 1/4 oz - 1 oz
1 troy oz = 1.09714286 ounces.
1 oz
1 pound 1 ounce
1 oz
1
Usually 1 oz. or less.
1 oz. Look at his drivers permit.
one half of a oz
0.5 oz