Baby Formula Calculator

The American Academy of Pediatrics (AAP) bases formula amounts on body weight: about 2.5 ounces of formula a day for every pound your baby weighs, up to about 32 ounces a day¹. This calculator applies that rule, then splits the total across a typical number of feeds for your baby's age.

What This Calculator Measures

It gives an average starting amount for a healthy, full-term baby on standard infant formula, from birth to 12 months. It does not measure hunger, growth or health. Every baby is different, and how much and how often a baby feeds depends on their needs².

The Formula

Formula per day (oz) = 2.5 x weight in pounds, up to 32 oz

Formula per feed = formula per day ÷ feeds per day

Metric: about 163 mL per kg per day, up to about 945 mL (32 oz converted exactly; AAP rounds this to 960 mL)

The 2.5 ounce rule and the 32 ounce daily maximum both come from AAP guidance for parents¹. In the UK, the NHS uses a range of about 150 to 200 mL per kg per day, from the end of the first week to 6 months³.

How This Calculator Computes Your Result

Enter weight in pounds and ounces or kilograms, and age in weeks (0 for the first week) or months. Feeds per day is optional; if blank, the tool uses a typical number for the age.

You get formula per day and per feed, in US fluid ounces and mL (1 fl oz = 29.57 mL), and about how many hours apart the feeds are. For babies from 1 week to 6 months it also shows the NHS range for their weight. In the first week it shows 1 to 2 oz per feed instead of the weight rule, since the AAP advises no more than about that per feed in the first week¹.

Example: a 3-week-old baby who weighs 9 lb 4 oz may take about 23.1 oz (685 mL) a day. Over 8 feeds, that is about 2.9 oz (85 mL) per feed, every 3 hours.

What Your Result Means

Your result is an average. Intake changes with growth spurts, illness and teething³. These are the typical amounts by age that the AAP and CDC describe¹ ²:

At 2.5 oz per pound, a baby reaches the 32 oz maximum at 12.8 lb (5.8 kg). From that weight on, the daily result stays at 32 oz. The AAP says a baby should usually drink no more than an average of about 32 ounces in 24 hours¹.

Following Your Baby's Hunger and Fullness Cues

The CDC says babies generally take what they need at each feeding and stop eating when full². Signs of hunger in babies up to 5 months include hands to the mouth, turning toward the bottle, smacking or licking lips, and clenched hands⁴. Signs of fullness include closing the mouth, turning the head away from the bottle and relaxing the hands⁴.

Your baby does not need to finish a bottle⁴. The AAP notes that a baby who becomes fidgety or easily distracted during a feed is probably finished, while one who drains the bottle and keeps smacking their lips may still be hungry¹.

Signs Your Baby Is Getting Enough

Weight gain and the number of wet and dirty diapers show whether a baby is getting enough formula³. The NHS says a baby should have around 6 wet diapers a day from a few days after birth³. Regular weigh-ins at checkups track growth over time (the Baby Weight Percentile Calculator compares weight with WHO charts).

If your baby often seems to want much more or much less than the usual amount, the AAP suggests talking with your pediatrician¹. Fewer wet diapers than usual or slow weight gain are also worth raising with your pediatrician.

Mixing Formula Safely

The calculator tells you how much prepared formula, not how much powder. Always use the scoop and the amount of water on the formula label, and mix it exactly as the maker directs⁵. Never water formula down to make it last longer. The AAP warns that too much water can slow growth and upset the balance of sodium, potassium and calcium in the body, which can lead to seizures⁵. Ready-to-feed formula needs no water at all⁵.

Formula After 6 Months

Most babies start solid foods at about 6 months⁶. At first, they still get most of their nutrition from breast milk or formula, and solids are added gradually⁶. As your baby eats more food, formula intake goes down. So from 6 months, treat the result as an upper guide, not a target.