How to Switch Baby From Formula to Milk: At 12 Months, Over 1 to 2 Weeks

Here is the short version: most babies switch from formula to plain whole cow's milk at 12 months, the change is phased in over 1 to 2 weeks by mixing prepared formula with milk, the milk goes into a cup rather than a bottle, and the target after the switch is about 16 to 24 oz (475 to 710 ml) a day. Toddler milk is not needed, and food, not milk, becomes the main source of nutrition.

If you are searching for how to switch baby from formula to milk, you are asking one of the most common first birthday questions. This guide walks through the whole handover: the right moment, a day by day plan, the whole milk versus toddler milk decision, how much to serve, what to do when your baby refuses, and the nutrients (iron and vitamin D) that need a little attention once formula is gone.

Key Takeaways

▸ Whole cow's milk can replace formula from the first birthday, not before
▸ Phase it in over 1 to 2 weeks: mix prepared formula with milk and shift the ratio every few days
▸ Plain whole milk until age 2; toddler milk is not necessary for healthy children
▸ Aim for 16 to 24 oz (475 to 710 ml) a day, served in a cup with meals
▸ Keep iron rich foods on the plate and give vitamin D as your doctor advises, because cow's milk contains very little iron

When to Switch From Formula to Milk

The American Academy of Pediatrics (AAP), the CDC and the NHS all agree on the timing: whole cow's milk is suitable as a main drink from 12 months. Before that, formula or breast milk stays the main drink. Cow's milk contains very little iron, more protein and minerals than a young baby's kidneys handle comfortably, and it can cause tiny amounts of blood loss in the gut of babies under 12 months. None of that is a problem once your child is a year old and eating a varied diet.

The birthday is a guide, not a switch that flips on the day. Your baby is ready when three things are true:

✓ They are around 12 months old (talk to your pediatrician first if your baby was born prematurely or has a medical condition)
✓ They eat three solid meals a day with a good range of foods, including iron rich ones such as meat, beans, lentils or fortified cereal
✓ They can take sips from a cup, even if it is messy

If your baby was breastfed rather than formula fed, nothing needs to change at 12 months. You can keep breastfeeding for as long as you both want; cow's milk is then simply an option, not a replacement. Our guide on how long babies drink formula explains why the first year is the formula year, and will my baby drink less milk when starting solids covers the earlier shift, when solids first joined the bottles.

How to Phase Formula Out Over 1 to 2 Weeks

Plenty of babies accept plain whole milk on day one. If yours does, there is no rule that says you must go slowly. But a gradual mix helps babies who notice the different taste, and it gives the gut a few days to adjust to the new protein and fat profile. This is the schedule most families use:

Days	Mix in each cup	What to watch
Days 1 to 3	3 parts prepared formula, 1 part whole milk	Acceptance of the taste, normal stools
Days 4 to 6	Half formula, half whole milk	Any constipation, tummy discomfort or rash
Days 7 to 10	1 part formula, 3 parts whole milk	Appetite for solid meals stays good
Days 11 to 14	Whole milk only, 16 to 24 oz a day	Milk with meals, water in between

A second approach works just as well and suits babies who hate mixed drinks: replace one feed at a time. Start with the midday feed (usually the one your baby cares least about), serve whole milk in a cup there, and keep the other feeds as formula. Every 2 to 4 days, convert another feed. The bedtime feed goes last, because it is the one most tied to comfort.

Important: always prepare the formula with water exactly as the tin says, and only then combine it with milk. Never stir formula powder into cow's milk. That makes the drink far too concentrated in protein and minerals for a baby.

Whole Milk vs Toddler Milk vs Plant Drinks

Standing in the supermarket aisle, you will see three options that all claim to be right for a one year old. Here is how they compare.

Plain whole cow's milk

Pasteurized whole milk (3.25 percent fat in the US, 3.5 percent in Europe) is the recommended drink from 12 to 24 months. The fat matters: toddlers need it for brain growth and to absorb the fat soluble vitamins A and D. In the US, milk is fortified with vitamin D, which makes it a useful contributor to the daily target. Reduced fat milk is generally introduced from age 2; the NHS puts semi skimmed milk at 2 years for children who eat well and skimmed milk only from age 5. Never give raw (unpasteurized) milk to a toddler. Learn more about cow's milk in our food library.

Toddler milk (toddler formula, "stage 3")

Toddler milks are marketed for 12 months and up, and they are not what a healthy toddler needs. In its 2023 clinical report on older infant and young child formulas, the AAP concluded that these products offer no nutritional advantage over a balanced diet with whole milk, and that many contain added sugars. They also cost several times more than milk. The only exception is a child on a special medical formula for an allergy or a medical condition; in that case, your pediatrician decides when and how to move on.

Plant based drinks

If your child cannot have cow's milk because of an allergy, fortified unsweetened soy milk is the alternative that both the AAP and the CDC consider nutritionally closest to cow's milk. Almond, oat, rice and coconut drinks are low in protein and often in fat, so they are not suitable as a main milk drink for a toddler, even when they are fortified with calcium. Talk to your doctor or a dietitian before relying on any plant drink.

How Much Milk Per Day After the Switch

The guideline for 12 to 24 months is 16 to 24 oz (2 to 3 cups, about 475 to 710 ml) of whole milk a day. That is noticeably less than many babies drank as formula at 10 or 11 months, and the difference is deliberate: milk now supplements food instead of being the food.

More than 24 oz a day tends to cause:

✗ A full tummy and a poor appetite for meals
✗ Iron deficiency, because milk is low in iron, blocks some iron absorption and crowds out iron rich foods
✗ Constipation in some toddlers

Yogurt and cheese count toward the dairy total, so a toddler who eats a yogurt at breakfast and a few cubes of cheese at lunch can sit comfortably at the lower end of the milk range. For a month by month breakdown, see how much milk a toddler should drink from 12 to 24 months; for the specific question most parents type, see how much milk a 15 month old should drink. To see where the cups fit between meals and snacks, use our 15 month old feeding schedule.

Keep milk and meals in balance after the switch

The app shows age appropriate portions for every meal and snack and flags iron rich foods, so milk supplements the diet instead of replacing it.

App Store Google Play

Cups Instead of Bottles

The formula to milk switch is the natural moment to retire the bottle. The AAP recommends weaning from the bottle between 12 and 15 months, and no later than 18 months. Bottles at this age are linked to tooth decay (milk pooling around the teeth, especially in bed), to drinking far more milk than needed, and to ear infections when a baby drinks lying down.

1. Pick the cup

A small open cup or a straw cup teaches mature sipping. Hard spout sippy cups are a halfway house at best; if you use one, use it briefly.

2. Serve milk only in the cup, only at the table

Milk becomes part of the meal, like the food on the plate. Between meals, offer water.

3. Drop daytime bottles first, bedtime last

Replace the bedtime bottle with a cup of milk at dinner and a new wind down ritual (bath, book, song). Brush teeth after the last milk of the day.

4. Let the bottles disappear

Once you are down to zero, put them away. A bottle that is visible is a bottle that will be asked for.

What If Your Baby Refuses Milk?

Refusal is common and almost always temporary. Formula is sweeter than cow's milk, and a baby who has drunk warm formula from a bottle for a year is being asked to change taste, temperature and container at once. Change one thing at a time:

▸ Slow the ratio down. Stay at the 3 to 1 mix for a full week before moving on.
▸ Match the temperature. Warm the milk slightly at first, then cool it a little every few days.
▸ Change the container later. If cup plus milk is too much at once, do milk in the familiar bottle first, then move that same milk to a cup a week later. Or the other way round: water in the cup for two weeks, then milk.
▸ Serve it with food. Milk next to a plate of pancakes is more interesting than milk on its own.
▸ Do not force it. Offer, leave the cup within reach, take it away without comment when the meal ends.

And if your toddler simply never becomes a milk drinker? That is fine. Milk is a convenient package of calcium, fat, protein and (in fortified milk) vitamin D, but none of those nutrients require milk. Yogurt, cheese, kefir, fortified soy milk, tofu set with calcium, canned salmon with bones and beans all supply calcium. Toddlers aged 1 to 3 need about 700 mg of calcium a day; a cup of yogurt and a slice of cheese already get you most of the way there.

Iron and Vitamin D: The Two Nutrients to Watch

Formula is fortified with iron and vitamin D. Cow's milk contains almost no iron, and outside the US it is often not fortified with vitamin D either. That is why these two nutrients deserve a plan of their own.

Iron

Toddlers aged 1 to 3 need about 7 mg of iron a day. Aim for an iron rich food at most meals: red meat, poultry, fish, lentils, beans, tofu, iron fortified oat cereal, and pair plant sources with vitamin C (fruit, tomato, pepper) to boost absorption. Keep milk to the 16 to 24 oz range and serve it with meals rather than before them, so it does not blunt the appetite for the iron on the plate. Our iron rich foods guide has a full list.

Vitamin D

From the first birthday the daily target is 600 IU (15 micrograms). In the US, fortified whole milk provides roughly 100 IU per cup, so 2 to 3 cups cover a third to a half of the need; the rest comes from fortified foods, oily fish, eggs and, for many children, a supplement. The NHS recommends a daily 10 microgram vitamin D supplement for all children aged 1 to 4. Ask your pediatrician what is right for your child; the answer depends on where you live, the season and how much fortified milk your toddler actually drinks. Read more in our vitamin D guide.

Constipation, Allergy and Intolerance: What Is Normal, What Is Not

A few days of firmer stools are common during the switch and usually settle. Offer water with and between meals, serve fruit (pears, prunes, berries), vegetables and whole grains, and keep milk under 24 oz. If constipation lasts beyond two weeks or is painful, see your doctor.

A true cow's milk allergy is different and usually shows up quickly, within minutes to two hours: hives, swelling of the lips or face, vomiting, wheezing or sudden sleepiness. Any breathing difficulty or swelling is an emergency. Delayed reactions are also possible, over hours to days: worsening eczema, diarrhea, mucus or blood in the stool. Most babies with a milk allergy react to formula long before the first birthday, so a first reaction at 12 months is rare, but not impossible. Our article on signs of an allergic reaction in babies describes what to look for.

Lactose intolerance is uncommon in toddlers; it usually appears in older children and adults. A temporary version can follow a stomach bug and passes within a couple of weeks. Bloating, gas and loose stools without any skin or breathing symptoms point toward intolerance rather than allergy, and your doctor can help you tell the two apart. If your child has a confirmed cow's milk allergy, stay on the formula your allergist recommends and discuss fortified soy milk or another suitable alternative for the second year.

Frequently Asked Questions About Switching From Formula to Milk

Can I mix formula and whole milk in the same cup?

Yes. Prepare the formula with water as usual, then add the milk. Mixing is the gentlest way to bridge the taste difference. Just never add formula powder straight to milk.

Can I switch to cow's milk at 11 months?

Guidelines say 12 months, mainly because of iron. Starting the mixed phase a week or two before the birthday, so that the full switch lands at 12 months, is a reasonable compromise that many pediatricians accept. Ask yours.

Whole milk or 2 percent?

Whole milk until age 2 is the standard advice. Some doctors suggest reduced fat milk earlier when there is a strong family history of obesity or heart disease. That is an individual decision to make with your pediatrician, not a default.

Does the milk need to be warm?

No. Cold milk is perfectly fine for a toddler. Warming only helps babies who are used to warm formula; cool it gradually over a week or two.

Can I keep the bedtime bottle a little longer?

You can make it the last bottle to go, but plan its exit. Milk in bed is the single biggest cause of early tooth decay. Move the milk to a cup at dinner, then brush teeth before the bedtime routine.

Is lactose free milk okay?

Lactose free cow's milk has the same protein, fat and calcium as regular milk, so it is a fine choice if intolerance is confirmed. It is not an option for a cow's milk protein allergy.

What about goat's milk?

Pasteurized goat's milk can be used as a drink from 12 months, but it is not safer for a cow's milk allergy (the proteins are very similar) and is not naturally richer in the nutrients toddlers lack. If you use it, choose a fortified, pasteurized product and keep the same daily amounts.

How long does the transition take?

Most families are done in 1 to 2 weeks. A few babies take a month, and that is fine as long as milk stays within the recommended range and solids keep going well.

Final Thoughts

Switching from formula to milk is less a project than a handover. The essentials:

✓ Start at 12 months, once meals are going well
✓ Mix or swap one feed at a time over 1 to 2 weeks
✓ Plain whole milk, 16 to 24 oz a day, in a cup, with meals
✓ Skip toddler milk, keep iron rich foods and vitamin D in the plan

Every baby is different. Give it two weeks, change one variable at a time, and this will soon feel like the natural next step it is.