It can be tricky to figure out how much expressed breast milk you should put in a bottle – especially if your baby is usually breastfed!
This breast milk calculator was designed to help make that job a little bit easier. It is meant to be a starting point – based on average intake amounts – to help you make sure your baby gets enough to eat without developing a bottle preference.
New to bottle feeding your breastfed baby? This article should help – How to Give a Breastfed Baby a Bottle and Avoid Bottle Preference
How this Calculator Works
This calculator is based on the 24-30 ounces amount mentioned below, which is about how much your baby will be getting from about four weeks on.
Before that, some calculate the amount baby needs in a 24 hour period based on weight – which is about 2.5 ounces of breast milk per lb of bodyweight until they reach about 10 pounds (and this is after about the first week of life, where baby needs significantly less). If your baby isn’t quite four weeks yet, you can use the calculator at the bottom.
All babies are different and this calculator is meant to give you a starting place – always make sure you monitor your baby’s weight gain and diaper output! Watch for hunger cues, signs of fullness, and listen to your baby!
Expressed Breast Milk Calculator
Breast Milk by Weight Calculator
This calculator is really only accurate for babies 10-12ish pounds and under until about four weeks. Bottle amounts top out around 24-30 ounces.
More About How Much Baby Should Eat
It can be tricky to figure out exactly how breast milk your baby should get in a bottle.
Most research supports the idea that breastfed babies should get between 24-30 ounces in a 24 hour period from about four weeks until six months. While that can vary a little bit, it usually falls in this range. After six months, the amount tends to slowly start to decrease.
Using those numbers, I have created this bottle amount calculator. I am asked this question time and time again, so hopefully, this calculator will help you get a better idea of what your baby needs.
If you are just trying to figure out how much milk you need for work, I would put in your total number of feeds (bottle and breast). In general, though, I do suggest about 1-1.25 ounces per hour from the last time your baby ate.
When combined with paced feeding, this can help substantially with a bottle and flow preference. You want your baby to see their time at the breast as high supply and bottle as lower supply times.
If you are exclusively pumping, there can be a little more flexibility in bottle amounts (especially if the baby is sleeping through the night), and this calculator should be helpful for you to figure out those bottle amounts.
In general, eight feeds a day is pretty typical – though some babies will eat more and others will eat less.
The goal is not to give your baby the amount in the bottle that they would be getting from the breast. You should not use a weighted feed to determine how much your baby should be getting in a bottle – nor should you use how much you are pumping to determine how much baby is getting from the breast or that you should put into a bottle.
I hope that this breast milk calculator was helpful! Be sure to leave a comment if you have any questions. Good luck!