Formula Preparation and Handling

Proper preparation of powdered infant formula is important to ensure an infant is receiving the recommended levels of calories and nutrients in formula.

Safe preparation of infant formula begins with safe water. Water used for mixing infant formula must come from a reliable water source. If safe tap water is not available, bottled water or boiled water may be used. Learn more about clean water.

It is important that formula be prepared with correct water-to-formula ratios. Adding too little water to formula can burden an infant’s kidneys and digestive system, leading to diarrhea and dehydration. Adding too much water will dilute the formula and can lead to water toxicity and under-nutrition. Diluted formula provides inadequate calories, placing an infant at risk for stunting, wasting, developmental delays and/or infection. Always follow manufacturer’s instructions to ensure formula is prepared using accurate water-to-formula ratios.

Infant formula can be prepared in single bottle or large batches. It is preferable that infant formula be prepared one bottle at a time, since it is easier to ensure proper proportions of powdered formula to water. However, in many institutional settings infant formula is prepared in large batches for the convenience of staff and caregivers. Formula should be prepared in batches no larger than 1 liter. It is important that when preparing large batches, proper calculations are used in order to ensure optimal formula concentration.

Here is an example of the difference between single bottle and large batch amounts of powdered infant formula and water:

Single Bottle
9 grams of powder (1 level scoop) for every 60 milliliters (2 oz.) of water

Large Batch
153 grams (17 level scoops) for every 1-liter (34 oz.) of water

Single Bottle Preparation

To prepare a single bottle of powdered infant formula:

  • Wash bottle and bottle parts (nipple, ring, cap) with soap and water
  • Sterilize bottle in boiling water for five minutes
  • Prepare sterile water (bottled or water that has been boiled*)
  • Thoroughly wash hands with soap and water
  • Measure sterile water into clean bottle as indicated on the product label
  • Measure corresponding amount of powdered formula into the bottle as indicated on the product label
  • Secure nipple and ring to the bottle
  • Shake bottle until formula is well mixed
  • Do not shake bottle too much; excessive foaming may increase likelihood of feeding air to the infant
  • Use immediately or cover bottle with cap and refrigerate until use

*NOTE: After boiling, water should be cooled to at least 70º C before mixing with formula.

Large Batch Preparation

To prepare powdered infant formula in a large batch:

  • Wash bottle and bottle parts (nipple, ring, cap), large spoon, large bowl, and storage container with soap and water
  • Sterilize all preparation equipment in boiling water for five minutes
  • Prepare sterile water (bottled or water that has been boiled*)
  • Thoroughly wash hands with soap and water
  • Measure sterile water into clean bowl according to proper calculations for large batches of the indications on the product label (no more than 1 liter)
  • Measure corresponding amount of powdered formula into the bowl according to proper calculations for large batches of the indications on the product label
  • Stir until well mixed (powder is completely dissolved and no clumps remain)
  • Distribute mixed formula into clean, sterile bottles
  • Use immediately or seal in a container with an air-tight lid in a refrigerator until use

*NOTE: After boiling, water should be cooled to at least 70º C before mixing with formula.

Handling and Storing Formula

After mixing, formula should be used immediately or stored in a refrigerator (2º C – 4º C/35º F – 40º F). Bacteria can grow if formula is left at room temperature for too long. Bottles can be served at room temperature or cold, but can be warmed if desired.

Considerations for warming bottles:

  • Bottles can be warmed by holding under warm, flowing tap water
  • Bottles can be warmed by placing in a container of water no warmer than 48º C
  • Do not leave bottles in a pot of warm water for over 5 minutes
  • Do not microwave bottles, since this can create hot spots and cause serious burns

After feeding an infant, discard any unused formula. Prepared formula should be discarded within one 1 hour of feeding an infant. Bacteria can grow in room-temperature formula, and illness can spread from infant-to-infant if bottles are shared.

Storing powdered formula
Powdered formula should be stored tightly covered in a cool, dry area. Powdered formula canisters should be used within one month of opening. Formula should not be used past the stated expiration date printed on the canister.

Storing prepared formula
If prepared formula is not being used to feed a child immediately after mixing, it should be stored in a refrigerator. Bottles of formula prepared from powder should be stored in the refrigerator at 35 – 40º F (2 – 4ºC) for no longer than 24 hours. Unused, mixed formula should be covered and labeled with the date before refrigerating. Formula should be discarded if it is more than 24 hours old. Ready-to-use and concentrated liquid formulas are commercially sterilized during processing, so opened cans or bottles prepared from these forms can be kept for up to 48 hours in the refrigerator at 35 – 40º F (2-4ºC). Do not use prepared formula or formula from opened liquid containers if it is unrefrigerated for more than a total of 2 hours.

Learn more about formula preparation: