Baby Formula Calculator
pounds
ounces
Enter age in months (0–12)
Gender is informational; this calculator uses weight-based rates for all sexes
How many times per day do you plan to feed your baby?
Premature / Preterm Baby
Use higher intake rates (180–200 ml/kg/day) for premature infants
Enter Your Baby's Details
Add your baby's weight and age to see how much formula they need each day and at each feeding.
How to Use the Baby Formula Calculator
Enter Your Baby's Weight
Choose kilograms or pounds + ounces and enter your baby's most recent weight. Weigh your baby at home or use the weight from your last paediatrician visit. Accurate weight is the most important input — it directly determines the formula volume.
Enter Your Baby's Age
Select whether to enter age in months or weeks, then enter your baby's current age. For newborns under one month, using weeks gives a more precise age bracket. Ages 0–12 months are supported. If your baby is premature, toggle the preterm switch to apply higher intake rates.
Set Feedings Per Day
Enter how many times per day you plan to feed your baby. For newborns this is typically 8–12 times; for older infants it may be 4–6 times. The calculator will divide the daily total by this number to give you a per-bottle target volume.
Review Results and Export
Your daily formula range (minimum to maximum) and per-feeding amounts are shown in both ml and oz. Review the age-group chart to see how your baby's needs compare to other stages. Use the cost estimator to budget monthly formula spend, then export to CSV or print for your records.
Frequently Asked Questions
How much formula does a newborn need per day?
In the first 1–4 days of life, a newborn needs only 30–60 ml per kilogram of body weight per day due to their tiny stomach capacity. From day 5 through to three months, this increases significantly to 150–180 ml/kg/day — the highest intake rate relative to body size in the entire first year. A newborn weighing 3.5 kg might need between 105 ml and 210 ml on day 1, rising to 525–630 ml per day by the end of the first week. These amounts are then divided across 8–12 feedings throughout the day, meaning each bottle contains just 45–75 ml on average.
How do I know if my baby is getting enough formula?
The most reliable sign that your baby is getting enough formula is consistent weight gain. Most healthy newborns regain their birth weight within 10–14 days and then gain approximately 150–200 grams per week for the first three months. Other positive signs include 6–8 wet nappies per day, regular bowel movements, and a baby who seems satisfied after feedings and is alert and active during wakeful periods. If your baby consistently seems hungry after finishing a bottle, does not gain weight appropriately, or shows signs of dehydration (fewer wet nappies, dry mouth), contact your paediatrician promptly.
Can I overfeed a formula-fed baby?
Yes, it is possible to overfeed a formula-fed baby, though it is less common than parents fear. Unlike breastfed babies who control flow by unlatching, bottle-fed babies may continue to suck past fullness because the bottle flow is constant. Signs of overfeeding include excessive spit-up or vomiting after feeds, gassiness, discomfort, and weight gain above the 97th percentile. To help prevent overfeeding, use paced bottle feeding (holding the bottle horizontal, allowing baby to take breaks), and stop the feeding when your baby shows fullness cues such as turning their head away, slowing sucking, or becoming drowsy.
When should I increase formula amounts?
Formula amounts should be increased as your baby's weight increases, roughly every two to four weeks in the first few months when growth is fastest. Recalculate using this tool whenever your baby has a new weight measurement. Practical signs that your baby is ready for more include finishing every bottle quickly and then showing hunger signs, waking more frequently at night despite previously sleeping through, or seeming frustrated during feeds. Do not increase amounts based on age alone — always use current weight as the basis for calculation, since babies of the same age can vary considerably in size.
What about premature babies — are the rates different?
Yes, premature infants have higher energy needs relative to their body weight than term infants because they must complete the growth that would have occurred in the womb while also maintaining body temperature and organ development. Preterm infants are typically given 180–200 ml/kg/day of formula or breast milk, and may receive specialised preterm formulas or breast milk fortifiers that provide additional calories per millilitre. The preterm mode in this calculator applies the 180–200 ml/kg/day range. However, premature infant feeding is complex and must always be guided by a neonatal team or paediatric dietitian — this calculator is a general reference only.
When should my baby stop formula and switch to cow's milk?
According to the AAP and WHO, cow's milk should not replace formula or breast milk before 12 months of age. Before that point, a baby's kidneys and digestive system are not mature enough to handle the protein and mineral load in cow's milk. After 12 months, full-fat cow's milk (whole milk) can replace formula as the primary dairy source, alongside a varied solid food diet. Between 6 and 12 months, formula remains the primary nutrition source even as solid foods are introduced. After 12 months, children typically need only 2–3 cups (480–720 ml) of milk per day as part of a balanced diet.