How many ounces of formula per day for my 5 month old?

What the evidence says

There isn't one exact number that fits every baby, but most 5-month-olds drink somewhere between 20 and 40 ounces of formula a day, with 24 to 32 ounces being typical for many babies at this age.

One common way doctors estimate this is about 2.5 ounces of formula for every pound your baby weighs, spread across the day. So a 15-pound baby might take around 37 ounces, while a 13-pound baby might take closer to 32 ounces. Most babies settle around 32 ounces a day and don't need much more than that, even as they keep growing.

Canadian guidance from the Canadian Paediatric Society doesn't give one fixed ounce number. Instead it focuses on feeding your baby when they show hunger cues and stopping when they seem full, rather than watching the clock or the bottle markings. Canadian sources also confirm formula should continue until your baby is 9 to 12 months old, and solid foods usually start around 6 months, not before.

Watching your baby instead of the number on the bottle is the better approach. Signs your baby is getting enough include steady weight gain, regular wet diapers, and seeming content after most feeds. If your baby constantly seems hungry after a full bottle, or never seems to want a full feed, it's worth checking in with your doctor or public health nurse.

Since your baby is close to 6 months, this is also around the time solid foods can start. Once solids begin, formula amounts often naturally shift a bit, so don't worry if the number changes over the next few weeks.