Working out how much formula your baby needs can feel like a guessing game, especially at 3 a.m. The good news: there’s a simple rule of thumb, and your baby will help you fine-tune it. This guide covers typical amounts by age and weight, and why your baby’s cues matter more than any chart.
This is general information, not medical advice — check with your doctor, midwife or health visitor, and always follow the directions on your formula tin.
How much formula does a baby need per day?
For most healthy babies under 6 months, a useful starting point is about 150 ml of formula per kilogram of body weight per day. You then split that total across the day’s feeds.
A quick example:
- A 4 kg baby → about 600 ml a day
- A 5 kg baby → about 750 ml a day
- A 6 kg baby → about 900 ml a day
This is an average, not a target to hit exactly. Some babies need a little more, some a little less, and intake naturally varies from day to day — just like adults aren’t equally hungry at every meal. If you’d rather not do the maths, our formula feeding calculator turns your baby’s weight into a gentle daily estimate and a rough amount per feed.
How much formula by age?
Amounts climb quickly in the early weeks, then settle. These are typical ranges, not rules:
| Age | Per feed | Feeds per day |
|---|---|---|
| First few days | 30–60 ml | 8–12 |
| 2 weeks–1 month | 60–90 ml | 6–8 |
| 1–2 months | 90–120 ml | 5–7 |
| 2–4 months | 120–180 ml | 5–6 |
| 4–6 months | 150–210 ml | 4–5 |
By around 6 months, daily amounts tend to level off rather than keep rising, because solid foods start to fill part of the gap. Your baby may also drop a feed as they sleep longer at night.
Why cues matter more than exact amounts
Charts are a guide. Your baby is the real expert on their own appetite. Watching for hunger and fullness cues keeps feeding comfortable and helps avoid pushing too much.
Signs of hunger:
- Stirring, turning toward the bottle, opening their mouth
- Bringing hands to their mouth, sucking on fists
- Fussing or rooting (crying is a late sign — try to feed before that)
Signs of fullness:
- Slowing down or pausing for longer
- Turning their head away
- Closing their mouth or pushing the bottle out
- Relaxing their hands and body
If your baby drains the bottle and still seems hungry, it’s fine to offer a little more. If they leave some, that’s fine too — there’s no need to encourage them to finish.
How do I know my baby is getting enough?
Rather than counting every millilitre, look at the bigger picture over days, not single feeds:
- Weight and growth. Steady gain along their own curve is the strongest sign. Your provider checks this at routine visits.
- Nappies. Plenty of wet nappies (often around six or more in 24 hours once feeding is established) and regular dirty ones.
- Mood. A baby who is generally alert when awake and settled after most feeds.
If your baby seems constantly hungry, rarely satisfied, or feeding is becoming stressful, that’s worth a chat with your provider — not a sign you’ve done something wrong.
When should I adjust the amount?
Babies don’t grow in a straight line, so it’s normal to tweak amounts over time:
- Growth spurts. Around 2–3 weeks, 6 weeks and 3 months, your baby may want more for a few days. Following their cues usually sorts this out naturally.
- Weight gain. As your baby gets heavier, the per-kilogram rule means their daily total slowly rises — recheck the estimate every couple of weeks.
- Starting solids (around 6 months). Milk stays important, but daily formula often plateaus as food fills part of the day.
Always make up formula exactly as the tin says — the right scoop-to-water ratio matters for your baby’s safety. Don’t water it down to stretch a tin, and don’t add extra powder to make it “richer.”
What about ounces, and how often?
If your tin or bottle uses ounces, the same idea applies — just in different units. Roughly 2.5 oz per pound of body weight per day lines up with the 150 ml/kg guide. So a baby weighing about 9 lb (4 kg) lands near 22–24 oz a day. Use whichever unit your bottles are marked in; you don’t need to convert in your head at every feed.
As for timing, newborns usually feed little and often — every 2–3 hours, day and night. As your baby grows, feeds tend to space out and get bigger. Try not to wake a thriving, growing baby just to hit a number; if your provider has asked you to wake your baby for feeds (for example a very small or newborn baby), follow their advice instead.
A calm way to think about it
Start with the rough daily amount for your baby’s weight, divide it into the feeds that suit your day, then let your baby lead from there. Some feeds will be big, some small, and that evens out. Once solids begin, our starting solids guide is a natural next read. If numbers help you feel calmer, the formula feeding calculator gives you a personalised starting point in seconds — then trust your baby and your provider to fine-tune the rest.
This article is for general information only and isn’t medical advice. Always follow the directions on your formula tin and your healthcare provider’s guidance — they’re the best people to ask about your own baby.