Free weaning plan - Register here
How do you prepare formula milk? Your questions answered.
When feeding your little one, you want to get things just right. And if you’re wondering about how to prepare formula milk, you’re certainly not alone.
Below, you’ll find the answers to some common questions on how to prepare formula milk in a safe and hygienic way so that your baby feeds safely.
How to make a bottle of formula milk
When it comes to how to make your baby’s bottle, it’s very important to follow the instructions on the pack very carefully. This will ensure your baby gets the right amount of powdered baby milk formula with each feed. It will also help you safely prepare your baby’s bottle feed.
Feeding equipment - what do I need?
Here’s our handy list1:
- Baby feeding bottles - anywhere between 6-8 should be enough to keep you covered.
- Bottle teats. There are lots of different bottle teats available, but no evidence to suggest that one type is better than another. The most important thing is choosing the bottle teat with the correct flow for your baby - a slow flow is best for newborn babies.
- Bottle brushes to keep your baby’s bottles and teats clean.
- Sterilising equipment - take a look at our guide on how to sterilise your baby’s bottle.
- Baby milk formula, either powdered or ready-to-feed liquid.
Want more information on how to get bottle-feeding ready?
Your step-by-step guide on how to prepare formula milk
Here are all the steps you need to follow to prepare your baby’s formula feeds. Failure to follow instructions could make your baby ill:
- Wash your hands and sterilise all utensils according to manufacturers’ instructions.
- Boil 1 litre of freshly run tap water. Leave the kettle to cool for 30 minutes and no longer. Measure the required amount of water (refer to feeding guide) into a sterilised bottle. Be careful of scalding. Do not use artificially softened or repeatedly boiled water.
- Using the scoop provided, level off the powdered infant formula with a clean knife or the built-in leveller if provided. Do not press/heap the powder.
- Add the correct measure of powdered infant formula to the water (please refer to the pack instructions). Adding too many or too few scoops can be harmful. Place the sterilised teat and cap on the bottle and shake immediately, vertically and vigorously for at least 10 seconds until the powder is dissolved.
- Cool the bottle feed under a cold running water tap. Check the temperature and feed immediately.
What’s shakin’, baby?
Did you know that shaking your baby’s milk is a key part of perfectly prepared formula milk? Immediately after the powdered infant formula is added to the water, shake your baby’s bottle feed vigorously and vertically until all the powder has dissolved - this takes at least 10 seconds.
Top tips for formula milk feeds
Here are a few handy parenting hacks to make formula feeds as fuss-free as possible:
- Keep everything you need to prepare your baby’s bottle in one place. That way, you’ll know where everything is, saving time when your little one is hungry! Seb's mum says, “We had a dedicated space in the kitchen where we kept all of the baby feeding equipment. It saved me from searching the kitchen for bottles, teats and baby formula.”
- Ready-to-feed formula milk can come in handy for those night-time feed s, rather than using powdered formulations. “In those early days, I always kept a couple of bottles of ready-to-feed formula milk on my bedside table, along with a pre-sterilised bottle”, says George’s mum. “This meant that there was less disturbance and moving around. We could get straight on with feeding and enjoying those night-time snuggles.”
- A top tip from Isla’s mum? “Have a couple of nappies and a spare change of clothes close by when feeding. It just made things easier if she needed changing - especially at night.”
Any questions? Formula Preparation FAQs
Parenting is the ultimate plate-spinning exercise. You won’t be the first, and you certainly won’t be the last, to prepare a formula feed only to be distracted by a leaking nappy or an unexpected knock at the door. Or it might just be that your baby isn’t in the mood to drink the whole bottle of milk that you’ve just prepared.
On that basis, you might be wondering whether you can reheat your baby’s bottle of formula milk when they’re ready to feed again. The answer is no. The bottle is no longer sterile if your baby starts a feed but doesn't finish it. Bacteria can multiply very quickly at room temperature, so the safest option to avoid the risk of infection is to discard it and make up a fresh bottle2.
If your baby hasn't yet started drinking from the bottle of formula milk, it will be safe to use for up to 2 hours after you've prepared it. If it's been longer than 2 hours, it's safest to discard and make up a fresh bottle to avoid the risk of infection. You can reheat it within this window by standing the bottle in boiled water.
It may be that your baby enjoys their milk at room temperature, whilst others prefer it warm. You’ll soon know your baby’s preferences when it comes to feeding.
You should never reheat your baby’s bottle in a microwave. It can result in the milk heating unevenly, which can cause harmful burning.
We know that when it comes to parenting, it can feel as though there just aren’t enough hours in the day. Whilst preparing formula feeds in advance to use throughout the night is tempting, the safest option is to prepare formula and feed it to your baby straight away, as this reduces the risk of infection and tummy upsets2.
If you’re formula feeding, liquid ready-to-feed formula milk can be used to feed your baby on the go. Be sure to follow the preparation instructions.
Your little one can go from happy as a clam to beyond famished in no time at all. But there are no shortcuts here. There’s no ‘quick’ way to prepare formula, and you should always follow the instructions on the pack to ensure you’re preparing feeds safely for your baby.
If you know you’re likely to be short on time, liquid ready-to-feed formula milk can be used, as you’ll just need to decant into a sterilised bottle or beaker.
When you read the instructions on how to prepare a bottle of formula milk, you’ll notice that they also provide clear guidance on how to prepare tap water for use when making a bottle of baby formula.
You’ll need to boil 1 litre of freshly run tap water and leave it to cool in the kettle for no longer than 30 minutes. Leaving it to cool for 30 minutes means that the temperature of the water will be around 70℃. According to the World Health Organisation, Department of Health (UK) and the HSE, this is the right temperature for mixing.
The water needs to be at this temperature for two reasons. Firstly, to kill any harmful bacteria that may be present (as formula milks are not sterile), and secondly, to ensure that the water is not too hot when mixing it with the powdered infant formula, as there’s a risk of affecting its nutritional value.
The NHS doesn’t advise using bottled water to make up your baby’s formula milk. It can contain added sodium and sulphates and often isn’t sterile. You should always use tap water when preparing your baby’s bottles.
If your water supply is interrupted, read our guidance on preparing formula feeds without tap water.
Some parents use the Perfect Prep machine to prepare their baby’s feeds, however NHS and HSE do not recommend them as they do not offer the highest standard of safe formula preparation. If you choose to use one, then we recommend that you carefully follow the instructions provided by the manufacturer, as they will differ from World Health Organisation, Department of Health (UK) and HSE recommendations.
Whether you choose to use a Perfect Prep machine or not, we always advise that you follow the specific instructions on your pack of formula powder and use the scoop provided. This way, you can be sure you’re preparing formula safely for your little one.
Preparing your baby’s feeds as and when they need them isn't always possible. This is especially true if you’re out and about with your baby or going on a trip.
As mentioned above, we recommend that any formula not consumed by your baby and/or has had contact with your baby's mouth be thrown away after 2 hours. We recommend that any formula your baby doesn’t consume within two hours is thrown away. In these circumstances, you may want to use a ready-made liquid feed.
No. It’s never advisable to freeze formula milk. Try to prepare your formula feeds as your baby needs them, so they’re always freshly made.
Figuring out how much formula powder to use might be giving you a headache! For guidance on how much powder to add, you can look at our handy milk intake chart here.
Remember that the instructions on the formula pack are there to help and guide you, so always make sure that you read and follow them in the first instance when preparing your baby’s feeds.
IMPORTANT NOTICE:
Breastfeeding is best for babies and provides many benefits. It is important that, in preparation for and during breastfeeding, you eat a varied, balanced diet. Combined breast and bottle feeding in the first weeks of life may reduce the supply of your own breast milk, and reversing the decision not to breastfeed is difficult. The social and financial implications of using an infant formula should be considered. Improper use of an infant formula or inappropriate foods or feeding methods may present a health hazard. If you use an infant formula, you should follow manufacturer’s instructions for use carefully – failure to follow the instructions may make your baby ill. Always consult your doctor, midwife or health visitor for advice about feeding your baby.
- NHS Start for Life. Things you need for formula feeding [online]. Available at https://www.nhs.uk/start-for-life/baby/feeding-your-baby/bottle-feeding/how-to-make-up-a-feed/things-you-need-for-formula-feeding/. [Accessed February 2025]
- NHS. How to make up baby formula [online 2023]. Available at https://www.nhs.uk/conditions/baby/breastfeeding-and-bottle-feeding/bottle-feeding/making-up-baby-formula/. [Accessed February 2025]
Join our baby club
Ready to stop worrying about what other people think and do what feels right to you? We’ll give you the support you need to follow your instincts and enjoy parenthood to the max:
Helpful emails
Non-judgemental support
Free weaning plan
Tips from real parents
More from baby
Explore our baby hubs
Baby topics
Need free advice with a smile? Get in touch with our dedicated Care team.
Ask us a question (8am - 8pm Monday to Friday, 10am - 4pm Weekends)
Messenger
Contact us on Facebook ( 10am–10pm Mon–Sat, 10am–5:30pm Sun)
Call us
Call us on 0800 977 8880 (8am - 8pm Monday to Friday)
FAQs
Get answers to your most frequently asked questions