For the most part, bottle-feeding is pretty straightforward: Once you’ve selected the bottle you want to use and filled it up, you just need to find a comfy seat and offer it to your baby. But before you get to this sit-and-feed moment, the formula must be chosen, bought, sometimes prepared and often stored — which means you'll need a bit of know-how before you mix up that very first baby bottle.
Whether you're formula-feeding exclusively or supplementing breastfeeding with formula, here's everything you need to get started.
What is baby formula?
Baby formula is an infant nutrition source that’s made to mimic the nutrients of human breast milk. The production and distribution of baby formula in the U.S. is strictly regulated by U.S. laws and the Food and Drug Administration (FDA).
Formula may come in three main types:
- Powdered formula: You add water to the powder (this is usually the most affordable option)
- Concentrated liquid formula: You add water here, too
- Premixed, ready-to-use formula: With this type, you just need to open and serve (no need to add water, but it’s also the most expensive)
Whether you choose a generic or name-brand option, know that infant formula is carefully crafted to contain dozens of important nutrients your baby needs for optimal growth, including vitamins, minerals, protein, fats, carbohydrates, calcium and electrolytes.
Most formula for infants today also contains DHA (docosahexaenoic acid) and ARA (arachidonic acid), omega-3 and omega-6 fatty acids, respectively, that play an important role in brain function.
Types of baby formula
Here's a look at the most common types of infant formula to choose from:
Milk-based, iron-fortified formula
Cow’s milk-based formulas, which make up 80 percent of the formula sold in the U.S., contain proteins that are made easily digestible, milk sugar (lactose, which closely resembles breast milk) and vegetable oil, which is substituted for the fat found naturally in milk.
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Because iron is so essential for infant growth and development, the American Academy of Pediatrics (AAP) recommends iron-fortified formula for most babies until at least their first birthday. If needed (ask the doctor), there’s also lactose-free cow’s milk-based formula on the market.
Note that cow’s milk is not recommended for babies younger than 12 months because it doesn’t provide the complete nutrition developing infants need. However, during the 2022 formula shortage, the AAP adjusted their recommendation to say that if you can't find formula anywhere, whole cow's milk may be a temporary alternative for babies 6 months and older. This is not ideal and should not become routine, the AAP says, and infants should switch back to formula as soon as it's available.
Hydrolyzed formula
The protein content in this type of formula is broken down into smaller proteins, making it easier for a baby to digest — which is why it's also known as predigested formula. Hydrolyzed formula is often lactose-free and may be labeled hypoallergenic.
There's a lot to consider when trying a hydrolyzed or partially hydrolyzed formula (it’s often more expensive, for example), so talk to the doctor about formula for your allergy-prone baby before you make that choice.
Soy-based formula
Soy-based formulas are made from soybeans supplemented with vitamins, minerals and nutrients. But because soy formulas differ more from human milk than cow's milk, they aren't usually recommended except in certain circumstances — for example, your baby has a cow's milk allergy. Keep in mind, though, that it's common for infants with a milk allergy to also be sensitive to soy protein.
The AAP maintains that soy-based formula should only be used in a handful of situations, like in the rare instance that a baby cannot tolerate lactose, a type of sugar found in milk. While lactose-free options like soy formula are as nutritionally sound as the others in this list, check with the pediatrician before starting on one. It could be that the intolerance your baby is experiencing is temporary or due to something other than lactose.
Special formula
Some bottle-feeding babies require special formulations, including premature infants, babies allergic to both cow's milk and soy formulas, and babies with metabolic disorders such as phenylketonuria or PKU. These infant formula products, which aren't necessary or recommended unless your pediatrician says so, are often hypoallergenic, lactose-free or especially easy to digest. However, they are often very expensive.
Organic formula
Organic formulas are milk products produced without the use of pesticides, herbicides, antibiotics or growth hormones.
Probiotic and prebiotic formula
Some formulas for babies are now fortified with probiotics, gut-friendly bacteria that are supposed to prevent diarrhea in otherwise healthy children. Probiotics should not be given to chronic or seriously ill babies, and it’s unclear whether or not they're effective in treating diarrhea or preventing any other conditions.
Formulas made with prebiotics are yet another nutritional option and these may contain man-made oligosaccharides, which occur naturally in human breast milk and can promote a healthy lining in the intestine. Prebiotics are also added to some formulas in order to reduce infections in healthy children, but it's uncertain whether or not they're effective either. Check with your doctor if you have any questions.
How to prepare baby formula
Preparing your baby’s formula bottle is an important process, as each measurement impacts the nutritional content inside the bottle. To that end, it’s critical that you read labels carefully before you begin.
If you have any questions about mixing formula or you need a refresher, the Centers for Disease Control and Prevention (CDC) has a handy graphic.
Follow these steps to prepare baby formula:
- Suds up well. Wash your hands thoroughly with soap and warm water before preparing formula. And you should clean your countertop, and the bottle and nipple before you use them.
- Clean the can and opener. Before opening powdered formula, wash the tops of formula cans with soap and hot water, rinse well and dry. Use a clean, punch-type can opener to open liquid formula, making two openings (one large and one small) for easy pouring. Wash the opener after each use.
- Start with water. Always pour water in the bottle first and then add the powder.
- Check your tap. Most municipal water in the U.S. is safe to use for mixing formula, but if you’re not sure about the H20 from the tap in your area, contact your local health department.
- Measure precisely. Portion out the exact amount of water and then powder per the manufacturer's instructions. Too much water can create less nutritional formula; too little can tax your baby’s kidneys and digestive tract, resulting in dehydration.
- Never dilute formula. It’s tempting to add a little more water to the bottles, either to save money by stretching what you have or if can’t get to the store. But this is dangerous, as watering down formula can cause nutritional deficiencies or seizures.
- Shake it. Give the bottle a good shake (rather than stirring it) to evenly distribute powder or concentrate.
- Don’t microwave it. It could scald your baby if it's too hot.
- Boil water if necessary. If your baby is under 3 months, was born prematurely or has a compromised immune system, boil water first, then let cool for five minutes. Pour water into a clean bottle, stir in formula, put on a nipple cap and shake. (Boiling the water first helps protect against microbes like Cronobacter.)
- Do a temperature check. Run the bottle under cool water or place it in an ice bath (not letting water get in the bottle or on the nipple cap) to cool until just warm, and test the temperature with a few drops on your wrist before feeding your baby.
- Serve quickly. Offer prepared formula within two hours of mixing it or within one hour of the start of a feeding. Not planning on using the bottle right away? Store prepared formula in the fridge ASAP and serve within 24 hours to prevent contamination.
- Refrigerate premade formula, too. You can keep bottles of ready-to-feed formula and the concentrated variety covered and in the fridge for up to 48 hours.
- Toss leftovers. Any formula left in the bottle after a feeding could harbor bacteria, even if you refrigerate it. Be sure to discard it and don’t be tempted to offer it later in the day.
- Clean up again. After each feeding, thoroughly wash the bottle and nipple.
How much formula should a baby eat?
As a general rule, babies need 2.5 ounces of formula for every pound of body weight. For the total number of ounces per day, multiply your baby's weight by 2.5 So if your infant weighs 10 pounds, she should be drinking 20 to 25 ounces per day.
Check the formula-feeding chart below for a month-by-month guide:
But you can start your newborn out slowly. A few days after birth, your baby will probably take about 1 to 3 ounces at each feeding. In fact, full-term infants at a healthy weight can be fed on demand, which means you can watch for cues so you can determine her hunger level. Here are some of the common ones you might spy:
- Sucking furiously on her hands, your shirt or your arm
- Nuzzling against your chest
- Opening her mouth
- Rooting reflex (turning the head to the side with her mouth open to find the food source, often after her cheek is stroked)
- Sucking on her lip or tongue, which can look like she's sticking her tongue out
- Making lip-smacking sounds
- Crying in a short, low-pitched wail that rises and falls
Gradually increase the ounces, adding more as the demand becomes greater, but never push your baby to take more or finish a bottle. As long as she's growing and putting on weight, seems content most of the time and isn’t spitting up large quantities, she’s likely getting the correct amount.
Need more guidance? You can always check in with your pediatrician about how much formula to give.
Top questions about baby formula
You’ve got formula questions — and we’ve got answers. Read on to learn about formula costs, whether you should always serve formula warm and if it’s safe to switch types.
What is the best baby formula for a newborn?
If your baby doesn’t have allergies, was born full-term and is generally healthy, the best baby formula just might be the one that you can find easily at a store near you and that your baby seems to enjoy. Your pediatrician can certainly make a formula recommendation and if you gave birth at a hospital, you might start off with the brand you were given there.
As for the various types of formula for sale, whether powdered, concentrated or ready-to-feed, know that all three are equally balanced in terms of nutrition and all are FDA approved if sold in the U.S.
Powdered formula is generally cheaper than the other two, though both powder and concentrated versions require extra steps to prepare.
How much does baby formula cost?
There's no getting around it: Formula can be expensive. You can expect to shell out between $1,200 and $1,500 (or more) on formula before your baby’s first birthday, which comes to about $100 to $125 a month. Prices vary depending on the type of formula you use. For example, specialized formulas can be up to 20 percent more expensive than the iron-fortified, cow's-milk variety.
The least expensive option is usually powdered formula that you mix yourself. Next comes liquid concentrate (just add water) and finally, at the top of the formula pyramid, ready-to-feed.
Looking for a way to keep costs down but not ready to give up on convenience? One approach is to splurge on ready-to-feed formula during your baby's first few weeks when sleep is hard to come by — and the last thing you want to do is measure and mix at 2 a.m.
Another way to save on formula? Try registering on the manufacturer's website for coupons and rebate checks. Buying generic formula will also save you money.
Should baby formula always be warm?
There is no health reason to warm formula, so if you’re weary or it’s the middle of the night, know that room-temperature bottles are perfectly fine. But if you do want to warm a bottle, heat it in a bowl of warm water, run warm water over it or use a bottle warmer.
Never microwave a formula bottle, which can create hot spots that could burn a baby’s mouth or throat, and always check the temp on the inside of your wrist before serving it.
How long can baby formula sit out after it’s mixed?
The safest way to feed formula to your baby is to offer it in a timely manner and store it safely.
A bottle of prepared formula should be used within one hour from the start of a feeding session or within two hours of preparation (if it has been at room temperature). If you’re not giving the bottle to your baby within two hours, refrigerate it and use within 24 hours.
As for that little bit of formula left in the bottle at the end of a feeding? It's safest to throw it out, since the combination of baby saliva and formula can prompt bacteria to grow in the bottle.
Does formula change a baby’s poop?
Generally, formula-fed babies have stool that smells stronger, is darker in color (it can even be brownish-green) and is firmer than a breastfed baby’s.
However, poop varies among babies and most smells and colors are usually nothing to worry about. Ask the doctor if you’re concerned about stool colors and always call if your little one's poop seems hard and pebbly, much thicker than peanut butter, very watery, red- or black-tinged, or has a white or chalk-like appearance.
Can you switch formulas?
Any formula change for your infant should start with a conversation with your pediatrician, as they can guide you to the best choice. That said, unless your baby requires a special type of formula, switching to a different type or brand is generally no issue.
If you can’t locate the exact brand or type that your baby normally drinks, your pediatrician can suggest a good alternative. In general, it’s fine to change brands, though it’s usually best to stick with the same type of formula (so like for like). This means if your baby was doing well on concentrated cow’s milk-based formula, you might look for this same form under a different label.
When do babies stop drinking formula?
Most babies should make the switch from formula to whole cow’s milk around their first birthday, but not before. Cow’s milk is not recommended for babies under 1 as it doesn’t contain the nutrients infants need and can be hard for their sensitive stomachs to digest.
Cow’s milk isn’t as sweet as formula (or breast milk), so the taste might take some getting used to for your newly minted toddler. If she’s a little wary, try making the transition by mixing cow’s milk into prepared formula, slowly increasing the ratio of milk to formula in the bottle (just make sure you premix the formula before mixing it with the milk) until your child has adjusted to all milk. At that point, aim to offer 2 to 3 cups (16 to 24 ounces) of cow’s milk daily.
Your baby's first birthday is also a good time to work on trading the bottle for a toddler sippy cup or open cup. Some parents opt to start serving cow’s milk from an open cup straight away, but a gradual approach works, too. The AAP recommends weaning your toddler off bottles by 12 to 15 months of age.
Safety tips when using formula
Baby formula is easier to use than ever. But you still have to be careful when buying, preparing and storing it.
Follow these tips to make sure formula is as safe as possible for your baby.
- Vet the container. When selecting formula, always check the expiration date. If it’s expired, recalled or damaged (leaky, dented, rusty or misshapen), don’t buy or use it.
- Mix it right. Check the label to see whether the formula needs to be mixed with water. If it does, follow the measurements to the letter. Formula that's under-diluted can lead to problems including dehydration, while over-diluted formula can interfere with growth and nutrition.
- Don’t make your own. Homemade formula is never safe — and the AAP strongly urges parents not to make their own infant formula. It’s impossible for a home cook to come up with all of the ingredients in the proper amounts, which means homemade formula won’t nourish your baby properly and might even be deadly.
- Be super clean. Certain germs, like Cronobacter, are a possibility in an open container of formula. To fight contamination on counters, the sink, container lids and bottles, clean surfaces and gear well with soap and water. You should also wash your hands for at least 20 seconds before preparing bottles, touching your baby’s mouth or pacifier, and after using the bathroom or changing diapers.
- Know your water. Boiling is a good idea for certain health conditions, but otherwise, tap is fine. Still, it’s good to know how safe your water is when mixing formula. If you don’t, have your supply tested and, if necessary, purified. Or use the cold-water faucet and let the water run for a minute to flush out the stagnant supply. Or just use bottled water (but not distilled).
- Toss leftovers. Bacteria from a baby's saliva can multiply in a bottle, so always discard leftovers. Worried about waste? Prepare smaller servings, such as 2 ounces at a time, and give a refill if she's still hungry.
- Keep prepared bottles refrigerated. If you're traveling away from home, store previously prepared bottles in an insulated container or a tightly sealed plastic bag with a small ice pack or a dozen ice cubes. The formula will stay fresh as long as most of the ice is frozen. Don't use pre-mixed formula that's no longer cold to the touch — it'll have to be tossed.
Figuring out the whole formula thing can seem like a lot at first. But take heart and know that once you find a formula your baby likes and you learn about preparation and safe storage, you’ll settle into a good feeding routine. And before you know it, making formula bottles will become second nature.
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