If its over the 4oz line and it's just below the 2oz line then she's had whatever is left so just over 2oz? There's also measurements on the plastic lid that you could pour it into to see how much is actually left in there?
You are meant to count it by how much water you put in because the added formula is just displacing the water but it’s difficult to judge to be honest. As Lauren said, the lids have measurements on so when I empty the bottle I measure it and then go roughly in between the 2 😂
Even though it takes it over the line, it’s still 4oz. So if she’s finished the bottles, she’s had 4 oz. The powder doesn’t add more milk, it just weighs on the water to make it looks like there’s more. It’s still 4oz of water. I believe the lid is 30ml worth if that helps to see what’s left. (1oz)
We went to a dietician when my LO was younger & he said to actually count the ‘displacement’ as volume. Because overall that is still what baby would be drinking. 4oz of prepared formula makes 4.4oz total volume of feed, 5oz is 5.5, 6oz is 6.6 and so on. To figure out how much is left below the 2oz line you can pour it into the lid which has measurements on the side x
Same as comments above, I pour into the lid and work it out like that x
The lid goes up to 50ml, so worth pouring any left over in there if you want an exact measurement
I always looked at how much was in the bottle after it had been made, and judged it from that.