How to Prepare and Store Baby Formula: Steps, Water and Storage Times

A bottle you mixed before the last nap, a half-finished feed at 3 a.m., a can that has been open for weeks: knowing how to prepare and store baby formula, and how long formula is good for once mixed, is one of the most common questions parents ask.

The short answer: use prepared baby formula within 2 hours of making it and within 1 hour after your baby starts drinking it. If you will not use it within 2 hours, put it in the refrigerator immediately (40°F or colder) and use it within 24 hours of preparation. Throw out whatever is left in the bottle after a feed. These times come from the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP).

This guide covers powdered baby formula: storage times and reheating, step-by-step preparation, which water to use, scoops versus weighing, how many scoops per bottle size, and how many bottles to have. Guidance was checked on November 8, 2026. Your formula's own label comes first: if its instructions differ from anything here, follow the label, and ask your pediatrician about your baby.

How Long Is Baby Formula Good For? Storage Times at a Glance

Your label comes first: This table is general U.S. guidance, not permission to go past your formula's own label. Some labels, especially UK and European ones, are stricter, for example asking you to make every feed fresh or to use an opened can within 3 or 4 weeks. When the label is stricter, follow the label.

At room temperature, CDC uses two clocks: one starts when you mix the bottle, the other when your baby begins to drink from it. Use the formula within 2 hours of preparation and within 1 hour from the start of the feed, whichever comes first. Prepared formula that goes straight into the fridge, untouched, follows the refrigerator limit instead.

Unopened cans need a cool, dry, indoor spot too. If a delivery sat in the sun or you are wondering about a can left in a hot car, our guide can baby formula go bad in heat? covers storing powder in warm weather.

How Long Is Formula Good in the Fridge?

Up to 24 hours from when you mixed it. If you are not going to use a prepared bottle within 2 hours, put it in the refrigerator immediately, at 40°F or colder, and use it within 24 hours of preparation, as long as your baby has not drunk from it. AAP suggests labeling each bottle with the date and time you mixed it and keeping prepared bottles at the back of the fridge, where the temperature stays more consistent than in the door. Once your baby starts feeding, the 1-hour clock applies.

Why Leftovers Go in the Trash

Once your baby drinks from a bottle, saliva mixes with the formula, and CDC explains that this combination can grow bacteria. So the 1-hour clock starts at the first sip, and leftovers are not saved, even in the fridge. AAP suggests mixing smaller amounts, such as 2 to 4 ounces, so less is thrown away.

Can You Reheat Formula?

Not formula your baby has already drunk from. CDC says to throw out whatever is left in the bottle after a feed and not to refrigerate it to save for later. FDA notes that bacteria from a baby's mouth can keep growing even after refrigeration and reheating.

Prepared baby formula refrigerated right after mixing, and never fed from, keeps up to 24 hours from preparation in AAP's storage table. AAP says bottles can be warmed under a stream of warm tap water or in a bowl of heated water for a few minutes, then shaken well to get rid of hot spots. CDC adds: keep the water out of the bottle and off the nipple, test a few drops on your wrist, and never use a microwave, which heats unevenly and can burn your baby's mouth and throat.

Warming is optional. None of the CDC, AAP, FDA or NHS pages cited here says whether an untouched bottle can be warmed a second time, so ask your pediatrician if you are unsure. Once your baby starts a warmed bottle, CDC's 1-hour clock applies and what is left is thrown out. Some labels, such as HiPP's and Aptamil's UK labels, ask you to make every feed fresh and use it straight away; when your label says that, follow it.

How to Prepare Powdered Baby Formula, Step by Step

These steps follow CDC, AAP and FDA guidance for most babies most of the time. If your baby is younger than 2 months, was born prematurely or has a weakened immune system, read the extra steps below the list first. Read the directions on your formula before you start: water amounts, scoop sizes and water temperature differ from brand to brand.

1. Check the can. Make sure it is before its Use By date and has no dents, puffy ends or rust spots.
2. Wash your hands and clean the counter. Use a clean bottle and nipple; CDC's cleaning and sanitizing guidance covers how.
3. Measure the water first. Pour the exact amount of safe water the label lists into the bottle.
4. Add the powder. Use the amount the label lists, measured with the scoop that comes with that formula, filled loosely and leveled with the leveler or a clean, dry knife. Never add extra water or extra powder, and never add cereal or anything else to the bottle.
5. Cap and shake. CDC advises shaking the bottle to mix rather than using a blender.
6. Warm only if you want to. Formula does not need to be warmed. If you warm it, keep the bottle capped and hold it under warm running water without letting water reach the nipple or get inside, never use a microwave, and test a few drops on your wrist: warm, not hot.
7. Feed, then discard. Hold your baby and the bottle during the feed, stop when your baby shows signs of being full, and never prop the bottle or put your baby to bed with one. Throw out what is left and clean the bottle after every feed.

Getting the ratio right matters. CDC notes that too much water may mean the formula does not meet your baby's nutritional needs, and too little water can make your baby's kidneys and digestive system work too hard. AAP warns that watering down formula is dangerous. Never stretch formula to make a can last longer.

Extra Steps for Younger or Higher-Risk Babies

Powdered formula is not sterile. For babies younger than 2 months, born before 37 weeks or with a weakened immune system, CDC recommends boiling the water, waiting about 5 minutes, then mixing, because very hot water (around 158°F/70°C) is needed to kill germs such as Cronobacter; then let the bottle cool before feeding. FDA describes liquid ready-to-feed formula as the safest option for these babies. Some specialty formulas warn against hot water, so if your formula's label and this advice conflict, ask your pediatrician for a plan for that product rather than choosing on your own.

When the Label Says Something Different

Formula labels are written for the country where the product is sold, so directions differ. The UK's NHS takes a different approach from the U.S. guidance above: it uses freshly boiled water that is still at least 70°C (158°F) for every feed and advises making feeds one at a time, as your baby needs them. Many of the UK and European formulas Formuland sells carry directions written for that approach. If your formula's label asks for hotter water, a fresh feed every time or a shorter storage time, follow the label.

What Water Should You Use for Baby Formula?

Most of the time, safe tap water is fine. CDC says it is usually safe to mix powdered baby formula with tap water, filtered or unfiltered, following the directions on the container. If you are not sure your water is safe, contact your local health department.

Is Distilled Water Best for Formula?

Distilled water is one of the low-fluoride options CDC lists, not a requirement. AAP's advice is to use safe tap water most of the time and some non-fluoridated bottled water now and then. Whatever water you use, the formula label's directions on temperature and amount still apply.

Should You Weigh Formula Instead of Using the Scoop?

Follow the measuring method and exact amounts on your formula's label. CDC and FDA ask for the exact water the label lists, then the exact amount of powder. When the label uses scoops, AAP says to use only the scoop that comes with the container, because different brands, and different formulas within the same brand, use different-sized scoops.

• Fill the scoop loosely and level it with the leveler or a clean, dry knife (NHS). Do not pack it.
• Never use a scoop from another brand or another formula, and keep the scoop and powder dry.
• Do not make up your own scoop-to-gram conversion or change the concentration. If your pediatrician gives you a recipe, follow it exactly.

How Many Scoops of Baby Formula for 4, 6 or 8 oz?

It depends on the scoop in your can, so read the label before you count. Many U.S. formulas use 1 unpacked, level scoop per 2 fl oz of water, so 6 fl oz of water takes 3 scoops. The HiPP, Kendamil, Aptamil and Kabrita labels we checked use 1 level scoop per 30 ml of water (about 1 fl oz), and their tables pair 180 ml of water, the milliliter amount they list for 6 fl oz, with 6 scoops.

Kendamil's and Kabrita's U.S. labels also use 1 scoop per fluid ounce, so where a formula is sold does not settle it. The table shows each brand's own label or preparation page for the formula named, checked on November 8, 2026. Scoops are level and unpacked, and the water goes in first.

*The HiPP, Aptamil and Dutch Kabrita feeding tables stop at 180 to 210 ml of water per feed; 8 scoops in 240 ml is their 1-per-30 ml ratio, not a feeding amount. We could not find Holle's table on holle.ch, so read the one on your Holle pack.

In the baby formula mixing tables cited here, the water column is water, not the finished bottle. Enfamil's NeuroPro table notes that each scoop adds about 0.2 fl oz, and the German HiPP PRE table turns 180 ml of water into 200 ml of ready-to-drink formula. One fluid ounce is 29.57 ml, so 6 U.S. fl oz is about 177 ml, which HiPP's UK table lists as 180 ml; when your label is in milliliters, measure with the ml marks on your bottle rather than converting the recipe yourself.

• Use only the scoop that came with your can of baby formula. AAP notes that different brands, and different formulas within the same brand, have different-sized scoops, and Holle says its scoops are not always the same size because the scoop makes up for production differences in how densely the powder packs.
• Never swap scoops between brands, never add an extra scoop and never leave one out. CDC asks for the exact amount of water and formula listed on the container, and the NHS warns against adding extra powder or extra water.
• If your pediatrician gives you different mixing instructions, follow them: AAP says to mix formula as the manufacturer directs unless you are given changed instructions for a baby with special health needs.

This table only counts scoops; the steps above on safe water, hygiene, water temperature and higher-risk babies still apply.

Can You Mix Breast Milk and Formula?

This is a feeding decision to make with your pediatrician, who can give you handling instructions for a combined bottle. The CDC and AAP pages cited here do not give a recipe for combining the two, but their handling guidance still applies:

• Prepare the formula with water exactly as the label says first. Changing the amount of water changes the formula's concentration.
• Do not add fresh milk or formula to a bottle your baby has already drunk from; CDC notes that germs can grow quickly in a partially used bottle.
• Combining does not restart any clock: use the earliest deadline that applies to anything in the bottle, and throw out what is left after the feed.

How Many Baby Bottles Do You Need?

The CDC and AAP pages cited here do not say how many bottles to buy, so treat it as simple arithmetic: each feed needs its own clean bottle, so count the feeds between one wash and the next, then add one or two spares. In the first days, CDC describes formula-fed newborns taking 1 to 2 ounces every 2 to 3 hours, which is about 8 to 12 feeds a day. By the end of the first month, AAP says most formula-fed babies feed about every 3 to 4 hours and take 3 to 4 ounces at a time.

These are planning estimates, not a feeding schedule: feed your baby on cues of hunger and fullness. Smaller bottles may suit the first week, when AAP describes feeds of about 1 to 2 ounces; intake grows through the first month, and by 6 months AAP describes feeds of 6 to 8 ounces. Washing once a day means every feed still gets a clean bottle, never a rinsed one. For how much formula babies typically take at each age, see how much formula does a baby need.

Shop Baby Formula at Formuland

Formuland ships European and UK baby formula with duties included, free U.S. shipping on orders of $100 or more, and Subscribe & Save at 7% off eligible items. Check the age range and the preparation directions on each can.

• Stage 1 formulas from birth, including HiPP, Holle and Kendamil
• Kendamil ready-to-feed formula and HiPP ready-to-feed formula: do not add water; shake and follow the label's storage time once opened
• Kendamil, HiPP and Holle formula ranges

Disclosure: This guide summarizes public guidance from CDC, AAP, FDA and the NHS for general information. It is not medical advice. Your formula's label and your pediatrician come first, especially for babies born early, younger than 2 months, or with a medical condition.

Frequently Asked Questions About Preparing and Storing Baby Formula