Baby Formula Calculator
A rough guide to how much formula milk a baby usually needs each day and at each feed, worked out from their weight.
In kg, or lb if you picked lb above. For babies up to about 6 months.
Newborns often feed 8 to 12 times a day; older babies fewer, larger feeds.
Formula a day
675 ml to 900 ml
- Each feed
- 96 ml to 129 ml
- Weight used
- 4.5 kg
A 4.5 kg baby usually needs about 675 ml to 900 ml of formula a day, or 96 ml to 129 ml at each of 7 feeds.
How it's worked out
- A day
150 to 200 ml × 4.5 kg675 to 900 ml - Each feed
÷ 7 feeds96 to 129 ml
- This is a rough guide for babies up to about 6 months. Every baby is different: follow their cues for hunger and fullness rather than pushing them to finish a bottle.
- Make up feeds as the formula's instructions say. Talk to your health visitor, midwife or doctor if you're worried about feeding, weight gain or premature babies.
How it is worked out
The daily range is the baby's weight in kilograms × 150 ml and × 200 ml. Dividing by the number of feeds gives the range for each feed.
Making up feeds
Follow the instructions on the formula pack exactly when making up feeds.
Questions people ask
How much formula does a 4.5 kg baby need?
Usually about 675 ml to 900 ml a day. Over 7 feeds, that's about 96 ml to 129 ml a feed.
How is it worked out?
Babies usually need around 150 to 200 ml of formula per kilogram of body weight a day until they're about 6 months old.
Is there a daily maximum?
Yes. The American Academy of Pediatrics advises no more than an average of about 960 ml (32 fl oz) of formula a day, so the calculator never goes above that, even for heavier babies.
What if my baby wants more or less?
That's normal. Babies' appetites change from day to day. Follow their cues and don't make them finish a bottle.
Who should I ask about feeding?
Your health visitor, midwife or doctor, especially if your baby was premature, isn't gaining weight or seems unwell.
About this calculator
Formula and rules last checked 10 November 2026Written and tested by the CalculatorDex teamReport a problem
Sources: NHS 111 Wales: Infant formula, common questions · NHS: Formula milk, common questions · American Academy of Pediatrics (HealthyChildren.org): Amount and schedule of baby formula feedings