Feeding FAQ: 8-12 weeks – Formula Feeding

How do I move from breast to bottle feeding?

I have a 10-week-old baby boy, Ayton. He weighed 9lb 6oz at birth and has gained 8oz each week and is now 13lb 6oz. I have been breastfeeding him, and giving him a bottle of formula at the 10:30pm feed. He does seem to be a hungry baby, and I have been worrying that I’m not producing enough milk for him (despite knowing he is gaining the right amount of weight!)

I have twice followed the plan to increase my milk supply, which seems to work for a short while before it seems to decrease again. I am also giving him a top-up of expressed milk of 1-2 oz just before putting him down for his lunchtime nap, as he isn’t sleeping well at this time. Other than that he sleeps well, and for the last week he had been sleeping from 11pm to 7am, however the last two mornings he has woken at 5am and today he woke at 3:30am.

I have therefore decided that I’d like to start the transition to bottle feeding him. I’m going back to work after 6 months anyway, so it wouldn’t be much longer before I’d have to think about it anyway. It may seem like I’m giving up, but I can’t help but worry constantly about not producing enough milk, even though I know that is probably making it worse!

I read the section about weaning the baby from breast to bottle, so I know the time it is going to take, the order I drop the feeds and how much milk a baby should need each day according to weight, and I was interested to see how the example you give worked with regards to how the total amount is split.

Are there any guidelines as to how I should split the total amount he needs in 24 hours between each of the feeds? For example is there a rough percentage I should follow? The book mentions it is important to structure it possible so he gets more milk at certain times than at others.

I have no idea how much to feed him at the 11am feed once I have reduced the breastfeeding time for this feed, and likewise so on until I’m bottle feeding him entirely. He takes 7.5oz of formula at the 10:30pm feed if that helps.

I look forward to hearing from you.


For a baby weighing between 13 -14lbs the average amount he needs in the day is between 33-35 ozs. That is based on a baby needing 2.5 ozs per lb bodyweight. When you have that figure divide it by the number of feeds in the day. I imagine in your son’s case it will be about five: 7am, 11am, 2.30pm, 6pm and 10.30pm. You may still be splitting the 6pm feed and giving him a small feed before his bath at 5pm. So 34 ozs divided by 5 = 6.8ozs. Obviously you will make 7oz bottles to allow for Ayton to be hungrier at some feeds more than others. When I care for a formula-fed baby I am happy if there is a small amount of feed left in the bottle at the end, rather than it being drained each time. I then know the baby has had enough for his needs.

In order for you to structure the feeds properly, think how he feeds from you. Ayton should be hungry at 7am so will take a full feed of 7ozs then. He may only take 6.5ozs at 11am and maybe only 6ozs at 2pm. This feed is best kept smaller, especially if your baby still feeds at 5pm. The split feed could be 3ozs at 5pm followed by 4ozs at 6.15pm. Or he may be able to wait until after his bath and take a full 7ozs. As you say he already takes 7.5ozs at 10.30pm. So his total daily amount would be 34ozs. Not all babies keep exactly to this average amount. Some take 1oz or so more or less in 24hours but it is meant as a guideline so your baby is not over- or under-feeding. If you keep a record of his feed amounts over several days you will see his average intake and can adjust it according to his weight.

To answer the second part of your question: how much to top him up with when you first begin to introduce formula. I suggest you begin with a 2oz bottle. Feed your son as usual except stop him feeding about five minutes before he normally does and offer him the bottle. Let him take as much as he wants. He will probably not take the full amount. Depending how much is left you can roughly guess how much to increase the bottle by as he feeds less and less from you. It makes sense if making powdered formula to increase the amounts by a full ounce each time as it is easier to use full scoops. Be prepared for some wastage in the early days but you will know you son’s needs are being met if he continues to be settled between feeds.