How much formula does a baby need? A guide by weight and age

Standing in the kitchen at 3am wondering how much formula to make up is a rite of passage. The good news is there's a genuinely useful rule of thumb, and once you've seen it worked out in real numbers, the whole thing gets a lot less mysterious.

How much formula should a baby have per day?

For most healthy full-term babies from about a week old up to around 6 months, the guide is roughly 150 ml of formula per kilogram of body weight per day, split across their feeds.

So a 4 kg baby needs somewhere around 600 ml over a full day. Not per feed, per day. Some babies need a bit more, some a bit less, and that's normal. Premature babies and any baby under medical care follow their own plan from the hospital or PHN, so if you've been given specific amounts, use those.

One important caveat: in the first week feeds are tiny and frequent, and the amount builds up day by day. Don't expect the 150 ml/kg figure to apply on day two. It's a guide for once feeding is established, not for a brand new newborn.

How much formula does a 3 kg, 4 kg, 5 kg or 6 kg baby need?

Here's what the rule of thumb looks like in practice. The last column shows what the daily total looks like if your baby takes 6 feeds in the day, which many do.

Real babies don't take identical bottles all day, and that's fine. It's the daily total that matters, not any single feed.

How often should a newborn have a bottle?

Newborns typically feed every 2 to 3 hours, roughly 6 to 8 feeds in 24 hours, spacing out as they grow. But the timing is your baby's to set, not yours. Follow the baby's cues rather than the clock or the tin. The numbers printed on formula tins are averages across many babies, not targets for yours.

Two things never to do:

• Never force a baby to finish a bottle. When they turn away or slow right down, they're done.
• Never add extra scoops or cereal to a bottle. The recipe on the tin is the recipe.

How do I know if my baby is getting enough formula?

Forget the maths for a moment. The real signs a baby is getting enough are:

• Steady weight gain, which your PHN tracks at the check-ups
• Around 6 or more wet nappies a day after the first week
• A baby who's generally content between many of their feeds

If those three are in order, the exact ml count matters much less than you'd think at 3am.

Why is my baby suddenly hungrier than usual?

Growth spurts, commonly around 2 to 3 weeks, 6 weeks and 3 months, mean hungrier days where the usual amounts suddenly aren't enough. Feed to the cues. It settles again in a few days, and you don't need to change anything permanently.

How much formula should a 6 month old have?

From around 6 months, once solids start, milk amounts gradually reduce as food takes over some of the work. Formula (or breastmilk) stays the main drink until 12 months though, so the bottles don't disappear, they just shrink.

How do I make up a bottle safely?

One line on preparation, because it matters: make feeds fresh with water of at least 70°C and follow the HSE steps for safe preparation.

And if you're worried about intake, weight or reflux, the PHN and GP are the people to ask. This is a guide, not a prescription.

How do I know if my baby is getting enough?

Add up every bottle over a full day and compare it with the figure for your baby's weight above, then check the wet nappies. Most parents do this in their head at 3am and lose count. Lullagram does the adding up: log each bottle in a tap, and the day's total, the nappy count and the trend are on one screen, for both parents. It is free to try on Android, iPhone and web.