The FFF Quick-and-Dirty Guide to Formula Feeding: Mixing bottles

Hola, FFFs. And holla, because here is the quick-and-dirty guide to formula feeding I’ve been promising for ages! Actually, this is just Part One, but I will be posting new parts every so often until the entire guide is finished – at which point I will make it available via a tab on the right-hand side of the blog. Sound good?

I hope that this guide will offer some simple, accurate info for prospective (and current) formula feeders, without the subtle guilt-mongering prevalent in most formula feeding info. I figure the least we deserve is some evidence-based advice that doesn’t come via the formula companies.

Since many readers of this blog are experienced, educated formula feeders, I’m sure they will be able to elaborate on what I write in this guide. Be sure to read the comment threads, as I hope that there will be even more helpful hints and tips offered by the FFF community.

And as always, if you have any specific questions, please feel free to email me at and I will try and find the answer for you.

Happy formula feeding, lovely ones!

– The FFF

The FFF Quick-and-Dirty Guide to Formula Feeding:
Mixing Bottles

Mixing up a bottle of powdered formula isn’t rocket science, but it can be trickier than one might assume. First, always read the back of the can, because brands vary – some say to use an unpacked level scoop, others require a “packed” scoop. It’s important to have the proper ratio of formula and water because the wrong ratios can lead to stomach upset, which might make you think your baby is “intolerant” of the formula you’re using, when really it’s just that you’ve been using too much powder.

Finished reading the directions on your can? Cool. On to the next steps – and please note that I’ve broken this down into two categories, for newborns and babies older than three months. More precautions are necessary when your baby is a fragile newborn, since even the most insignificant illness can have a big impact on a human that tiny.You’ll notice that the instructions for older babies are much shorter. Like everything else about parenting, as the kid gets older, things get easier. If you can afford it, for the first month, use Ready-to-Feed formula rather than powdered. It’s safer (no chance of contamination from water, and less chance of contamination from your hands as all you have to do is pour it into a bottle or, in the case of those little nurser bottles some companies make, attach a pre-sterilized nipple. Easy-peasy, but pricey, so this is really just a short-term solution – but well worth it in the early days when the last thing you want to be worrying about is mixing formula the wrong way at 3am.)

Mixing Formula for Newborns

  • Measure the water. In terms of water, if you are mixing formula for a baby under three months old, the water source is pretty important. This is because if the water is contaminated with any bacteria, your baby can get sick. You know all those “facts” you hear about how formula fed babies get more gastrointestinal diseases? Most likely, it’s the water and not the formula which is causing these problems. (By the way, I’m sure you don’t need me to tell you this, but always wash your hands before you open the can and before you make up any formula. Duh, right?) Your best bet is distilled, bottled water (not all bottled waters are purified enough to reduce the chance of bacteria, and the distilling process helps gets rid of the little buggers), or simply boil a batch of water on your stove, let it cool, and keep it in the fridge. As long as you live in a community with a good water source, you’ll be able to use tap water (or tap water that’s been run through a home filtering system like a Brita pitcher) when your baby is a bit older.Pour the same amount of water into the bottle that you want to make of formula. So for example, if you are making a 4-oz bottle, pour 4 oz of water into the bottle.

(A little note about the “nursery water” that they sell at many grocery stores – this is usually fortified with fluoride, which may or may not be a good thing. Check out this post for more info.)

  • Measure the formula. Again, check if you’re supposed to use an unpacked or packed level scoop. Always use the scoop that the formula company provides, because they vary. The ratio for all formulas is one scoop to 2 oz of water (the exception to this is prescription Neocate, which uses a ratio of one formula scoop to one oz – thanks to FFF Perfesser for alerting me to this), so if you are making a 4-oz bottled, you’ll use 2 scoops; a 6-oz bottle, 3 scoops, and so on. Now, if you want to make an odd number of oz, things get trickier. You can eyeball a half-scoop, but this is obviously not an exact science, and I wouldn’t recommend it for a newborn. Instead, I’d suggest making more formula than you need, and pouring the remainder into another bottle which you can refrigerate and use at the next feeding. So for example, to make a 3-oz bottle, just make 6 oz of formula (6 oz of water/3 scoops of formula), shake up the bottle, and then pour 3 oz into another clean bottle to save for later. Cap that extra bottle and stick it in the fridge, and serve the other 3 oz immediately to your baby. When the time comes for the next feeding, warm the refrigerated bottle to room temp, and serve.
  • Insert any rings/discs that your bottle needs (for example, Avent bottles have little circular rings that need to be inserted before putting on the nipple; Dr. Brown’s use a whole elaborate contraption, and Born Free use a two-part disc. Other bottles don’t need anything but the nipple. I’ll leave figuring out the particular mechanics of your bottle of choice to the manufacturer’s website, because those things confuse the hell out of me. Took me like 3 weeks to figure out how to get the Dr. Brown’s system to work…) and then attach the nipple.
  • Mix or shake. Once everything is attached correctly, cap the bottle (or just place your finger over the hole in the nipple) and shake it vigorously. Then place the bottle on a flat surface and let it settle before serving. Check the nipple to make sure there are no clumps of formula stuck up in there, because it happens. A lot. Your other option is to use a formula mixer. Some folks swear by the little hand-held ones; they are supposed to mix the formula more smoothly and prevent air bubbles from forming. Personally, they didn’t work for me; the formula seemed more clumpy than when I shook the bottles by hand. I preferred using a formula pitcher, or even a salad dressing mixer (a heck of a lot cheaper than the commercial formula pitchers, and they do the trick). With these, you mix batches of formula and then pour the desired amount into bottles. Now, some warn against using these, as it is recommended that you make each bottle separately right before feeding. This is done, once again, to protect against bacterial contamination. Bacteria breeds the longer it is left out, so the theory is that if you have formula lying around – even in the fridge – it gives the bacteria a chance to grow and multiply. But if you are using pre-boiled or distilled water refrigerate the formula immediately and use it within a few hours, your chance of this happening is pretty tiny. You can also be extra-cautious and mix only the amount of formula that you need in the pitcher. One more caveat to using a separate pitcher/mixer – make sure you clean it after every use. And I’ll say it again – duh, right?
  • Make sure you feed your baby the bottle within 2 hours of mixing it up, unless you refrigerate it for later use. I used to be skeptical of this rule, but I’ve recently changed my mind. Just to clarify (thank to FFF Becky05 for this one), if you refrigerate the bottle, it stays good for 24 hours. But at room temp, you need to use it within 120 minutes, and once your babe has put it’s mouth to the nipple, it’s only good for 2 hours regardless of whether you stick it back in the fridge (although I still stick to my original belief that for an older baby, nursing a bottle for a little longer than 2 hours probably won’t hurt him/her, with a newborn, it’s better safe than sorry.)


Mixing formula for an older baby (3+ months)

  • Pour the water. At this point, you can use whatever water you personally drink. Bottled or tap (as long as it is from a safe water source – check with your city’s health department if you’re not sure) or filtered.
  • Scoop the formula. If you’ve recently switched formulas, double check that you are using the right amount – packed or unpacked – and make sure to use the scooper provided by the manufacturer. A hint for those of you as absent-minded as me – don’t try and have a conversation while mixing formula. You may find you suddenly have no idea if you’ve put in two scoops or three, at which point the whole batch might be ruined. It sucks. Pay attention and count aloud when you’re doing it. Seriously… or you’ll be crying over (unusable) milk.
  • Shake or mix. As long as there isn’t formula clumped in the nipple, you’re good to go. If you are worried about air bubbles, or your baby has an issue with excess gas, you can add a few of those infant gas drops (like Mylicon) to each bottle. But there’s really no need unless your baby is particularly gassy or spits up a lot. You can also just mix up the formula 15 minutes or so before a feed and let it settle – this will allow the air bubbles to subside.
  • Feel free to mix the day’s amount of formula in a formula pitcher (or even just a 32-oz Tupperware container), refrigerate, and use within 24 hours. If you’re using thickened feeds for a reflux baby, this is a total lifesaver – you can mix your batch to your baby’s specifications and not have to measure everything out for each bottle.

A few other hints:

  • For night time feedings: pre-measure water into bottles. Buy a formula dispenser, and measure out your formula into the dispenser. Bring all the stuff into your bedroom or master bath, and when you need to feed your baby in the middle of the night, all you need to do is pour the formula from the dispenser into the bottle. No fumbling around or measuring half-asleep.
  • The formula dispenser is also a great tool for outings. They have 3 little compartments, so you can measure out the amount of scoops you need for each bottle; bring bottles filled with water, and this way you don’t need to bring a cooler or anything when you’re out and about.
  • These instructions make it look like formula feeding is a massive undertaking. I promise you, it’s not. But I also strongly believe that most of the “dangers” of formula that are so widely discussed are due to improper formula handling. The older babies get, the lower the risk for major problems with bacteria and dehydration, and you can get more lax about things. But most of this stuff becomes pretty rote, anyway. Using ready-to-feed formula takes a lot of the stress out in the beginning, and as things get more chill in general, the less scary everything becomes. Just like breastfeeding has a learning curve, there’s a learning curve with formula feeding. You’ll get good at it and figure out what works best for you. As long as you have safe water, clean bottles, and accurately measured formula, you’ll be fine.


   Suzanne Barston (me) on

Suzanne Barston is a blogger and author of BOTTLED UP. Fearless Formula Feeder is a blog – and community – dedicated to infant feeding choice, and committed to providing non-judgmental support for all new parents. It exists to protect women from misleading or misrepresented “facts”; essentialist ideals about what mothers should think, feel, or do; government and health authorities who form policy statements based on ambivalent research; and the insidious beast known as Internetus Trolliamus, Mommy Blog Varietal.

Suzanne Barston – who has written posts on Fearless Formula Feeder.

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