Half a bottle left again, and you're wondering whether your baby has actually had "enough". The honest answer: there is no single magic number, and your baby is better at this than any chart. Here's how to think about it calmly.
The rough rule of thumb
A widely used starting estimate is around 150 mL of formula per kilogram of body weight per day for babies under about 6 months, divided across all the feeds in 24 hours. So a 4 kg baby would land somewhere near 600 mL a day total.
Note that this per-kg figure isn't fixed for life: it's highest in the early months and eases down as your baby grows — roughly 150 mL/kg under 6 months, dropping towards about 120 mL/kg and then around 100 mL/kg as they approach 12 months (because solids start covering more, and growth slows). So an older baby needs proportionally less milk per kilo than a newborn.
This is a guide, not a quota. Some babies need a little more, some a little less, and appetites swing from day to day — especially during growth spurts. Raising Children Network and the AAP both stress that the number on the tin or in a table is an average, not a rule your baby has agreed to.
| Stage | Amount |
|---|---|
| Newborn (first week)8-12 feeds a day, on demand (~150 mL/kg/day) | 30-60 mL per feed |
| 1-2 monthsevery 3-4 hours (~150 mL/kg/day) | 90-120 mL per feed |
| 2-6 monthsfeeds slowly space out (~150 mL/kg/day) | 120-210 mL per feed |
| 6-12 monthsplus solids, fewer milk feeds (~100-120 mL/kg/day) | 180-240 mL per feed |
Feed responsively, not by the millilitre
The most reliable "amount" is the one your baby asks for. Responsive (or paced) feeding means watching your baby, not the bottle.
- Offer when you see hunger cues: rooting, hands to mouth, lip-smacking, stirring and fussing. Crying is a late cue.
- Stop when you see fullness cues: turning away, slowing right down, relaxing their hands, pushing the teat out.
- Never pressure the last few millilitres. A baby who's done is done. Forcing the rest can lead to spit-up and teaches them to override their own appetite.
Paced bottle-feeding — holding the bottle more horizontally and pausing — lets your baby control the flow and is gentler on tummies. It's especially handy if you're combining breast and bottle.
Look at the week, not the bottle
One light feed, one big feed, a fussy evening — none of these mean anything on their own. What tells the real story over time:
- Wet nappies: roughly 6 or more heavy, pale wet nappies a day once feeding is established.
- Growth: steady gains along their own curve. Your child-health nurse or GP plots this; both the WHO and AAP charts follow a baby's own trend rather than chasing a percentile.
- A baby who is generally settled, alert when awake, and meeting milestones.
| Reassuring signs | Worth a chat with your nurse or GP |
|---|---|
| 6+ wet nappies a day | Far fewer wet nappies, very dark urine |
| Following their own growth curve | Crossing down through curves, or flat for weeks |
| Alert and settled between feeds | Persistently lethargic, very hard to rouse |
| Some day-to-day appetite swings | Sustained refusal, or never seems satisfied |
A few safety notes worth keeping
- Always make formula exactly as the tin directs. Never water it down to stretch a tin or scoop it stronger to "fill them up" — both can make your baby unwell.
- Don't add anything to bottles — no cereal, no honey (honey isn't safe under 12 months), nothing to help sleep.
A note on regional differences
Guidance is broadly aligned, but a few details vary:
- Vitamin D: the US AAP recommends a 400 IU/day vitamin D supplement for breastfed and partially-breastfed babies, and for formula-fed babies it's conditional — a supplement is recommended only while they're taking less than about 1 litre (32 oz) of vitamin-D-fortified formula a day. A fully formula-fed baby drinking that much or more generally doesn't need a supplement, because the formula is already fortified. Australian advice (including Raising Children Network) is broadly similar: several Australian sources recommend routine supplementation up to around 6 months unless formula intake is above roughly 1000 mL/day, alongside a separate risk-factor pathway (for example babies with darker skin or whose mothers were vitamin-D deficient). Ask your GP or child-health nurse what applies to you.
- Starting solids: AU (ASCIA, RCN), the US (AAP) and WHO all point to around 6 months (and not before 4 months) — once solids begin, milk volumes gradually ease down.
You're doing better than you think. Trust your baby's cues, watch the bigger picture over days and weeks, and lean on your child-health nurse, GP or doctor for anything that worries you — that's exactly what they're there for.