About 10% more. A little less actually but 10% is an easy number.

If the 40oz container is filled with 30oz of water and the rest is filled such that the ice is forced into the 40oz volume by the lid we'll first have a total "volume" of 40oz of combined ice and water.

When the ice melts it will take up 10% less volume. Staying with oz for simplicity, we'll consider it a measure of volume in this case. So, the final amount of water in the container once all the ice turns to liquid water is 10% less than the volume the ice originally occupied. So 10 oz reduces down to 9oz of occupied volume.

So the total loss off volume as compared to not putting ice in is 1oz of final water in the containers steady state condition.

It's pretty negligible even in the case of 1/4 of the container being filled with ice.