What this calculator does
Formula guidance is given per kilogram of body weight, and the rate per kilogram falls as a baby grows. Newborns in their first days take around 45 mL/kg; from five days to three months the figure rises to 150, then tapers back to 100 by six to twelve months.
The taper reflects solid food arriving. A 4.5 kg baby at the peak rate needs about 675 mL a day, which at six feeds is 113 mL each time.
The formula
The age band selects a millilitres-per-kilogram rate, which is multiplied by the baby's weight for the daily total. Dividing by the number of feeds gives the volume per feed.
| Term | Meaning |
|---|---|
| mL/kg per day | The guideline rate, which changes with age band. |
| Per feed volume | Daily total divided by the number of feeds. |
| Responsive feeding | Following the baby's hunger cues rather than a fixed volume. |
The inputs explained
| Field | What to enter |
|---|---|
| Baby weight (kg) | Baby weight in kilograms. |
| Age | Age band, which selects the millilitres-per-kilogram rate. |
| Feeds per day | Number of feeds per day, used to divide the daily total. |
When to use it
Working out roughly how much to prepare
A daily total helps plan how much formula to make up.
Checking a feeding pattern
Comparing actual intake against the guideline can be reassuring.
Understanding why intake changes
The per-kilogram rate falls with age even as total volume may rise.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How does the rate change with age?
The same weight across four age bands.
| Age band | Daily formula volume | In fluid ounces |
|---|---|---|
| 1-4 days | 203 mL | 6.8 fl oz/day |
| 5 days to 3 months | 675 mL | 22.8 fl oz/day |
| 3-6 months | 540 mL | 18.3 fl oz/day |
| 6-12 months | 450 mL | 15.2 fl oz/day |
Questions
Should I hold my baby to these volumes?
No. These are averages, and healthy babies vary considerably from feed to feed and day to day. Responsive feeding, following hunger and fullness cues, is the recommended approach, and your paediatrician or health visitor is the right source of guidance.
What if my baby takes much less than this?
Occasional smaller feeds are normal. Consistently low intake, poor weight gain, fewer wet nappies or a baby who seems unwell should be discussed with a healthcare professional rather than managed against a calculator.
Why does the rate per kilogram fall with age?
Partly because growth rate slows after the first months, and partly because solids begin to contribute from around six months. Total volume may still rise even as the per-kilogram figure falls.
Does this apply to breastfed babies?
No. Breastfed babies self-regulate intake and volumes are not measured, so the guideline does not translate. Mixed feeding should be discussed with a health professional.
For correcting age in premature babies, see the adjusted age calculator. For predicting adult height, see the mid-parental height calculator.