Baby Feeding Amount Calculator (per Feeding)
Estimate how much milk a formula-fed baby needs per feeding from body weight, feeds per day, and the standard daily intake per kilogram — in millilitres or ounces.
Last updated: May 2026
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About this calculator
Infant feeding volumes scale with body weight, not age alone, which is why pediatric guidance is expressed per kilogram. The widely used clinical rule of thumb is that a healthy, term, formula-fed baby needs roughly 150 millilitres of milk per kilogram of body weight per day, with a normal range of about 120–200 ml/kg/day depending on growth and appetite. This calculator multiplies the baby's weight by that per-kilogram daily intake to get the total daily volume, then divides by the number of feedings in a day to get the amount per feeding — the figure parents actually need when preparing a bottle. An optional unit selector converts the result from millilitres to fluid ounces by dividing by 29.5735 ml per ounce, because bottles are marked in ounces in some countries and millilitres in others. Every input is used: weight and the per-kilogram rate set the daily requirement, the feeds-per-day input splits it into practical bottle sizes, and the unit selector chooses the output scale. The result is an estimate for formula-fed infants; breastfed babies feed on demand and self-regulate, so volumes aren't measured the same way, and any feeding concerns should be discussed with a pediatrician.
How to use
Worked example. Your baby weighs 4 kg, you use the standard 150 ml/kg/day intake, you feed 8 times a day, and you want the answer in millilitres. Step 1 — daily requirement: 4 kg × 150 ml/kg = 600 ml per day. Step 2 — per feeding: 600 ml ÷ 8 feeds = 75 ml per feeding. Step 3 — convert if needed: switching the unit to ounces gives 75 ÷ 29.5735 ≈ 2.5 oz per bottle. As the baby grows the numbers rise: at 5 kg the daily total is 750 ml and each of 8 feeds is about 94 ml (3.2 oz). If the baby moves to fewer, larger feeds — say 6 a day at 5 kg — each feeding climbs to 125 ml (4.2 oz). These are starting estimates; actual intake varies with the individual baby and should be guided by hunger cues, wet diapers, weight gain, and your pediatrician's advice.
Frequently asked questions
How much formula should a baby drink per feeding?
A common clinical starting point is about 150 ml of formula per kilogram of body weight per day, divided by the number of feedings. For a 4 kg baby fed 8 times a day, that's 600 ml ÷ 8 = 75 ml (about 2.5 oz) per bottle. The normal range is roughly 120–200 ml/kg/day, so appetite varies. As weight increases or feeds become less frequent, the per-feeding amount grows. Use this as a guide alongside your baby's hunger and fullness cues, wet-diaper counts, and weight checks, and follow your pediatrician's specific recommendations.
How many ml of milk per kg per day does a baby need?
The standard pediatric estimate for a healthy, term, formula-fed infant is about 150 ml per kilogram of body weight per day, with a typical range of 120–200 ml/kg/day. So a 4 kg baby needs roughly 600 ml a day, and a 5 kg baby about 750 ml. The per-kilogram approach is used because intake tracks body size rather than age. This calculator multiplies weight by the per-kg rate you enter, so you can use 150 as a default or adjust within the normal range based on your baby's growth and your pediatrician's guidance.
How do I convert baby bottle amounts from ml to oz?
Divide millilitres by 29.5735 to get US fluid ounces, since one ounce equals 29.5735 ml. So 75 ml is about 2.5 oz, 90 ml is about 3 oz, and 120 ml is about 4 oz. Bottles are commonly marked in ounces in the United States and in millilitres elsewhere, which is why this calculator offers both. Select ounces as the output unit and it applies the conversion automatically. For practical purposes many parents round to the nearest quarter- or half-ounce mark on the bottle.