Most babies can stop drinking formula at 12 months old. At that point, whole cow’s milk becomes the recommended replacement, along with a balanced diet of solid foods. Before 12 months, a baby’s digestive system and kidneys aren’t mature enough to handle cow’s milk as a primary drink, which is why formula (or breast milk) remains essential through the entire first year.
Why 12 Months Is the Cutoff
Cow’s milk contains roughly three times more sodium and potassium than breast milk, four times more calcium, and six times more phosphorus. For an older child, those minerals are fine. For a baby under one, they create a much higher workload on the kidneys. The resulting strain narrows the margin of safety if your baby gets sick or dehydrated from a stomach bug or fever. Formula is specifically designed to match what an infant’s body can process.
Iron is the other major concern. Cow’s milk is low in iron and can irritate the lining of a young baby’s intestines, causing tiny amounts of blood loss that add up over time. Babies who drink cow’s milk too early are at increased risk for iron-deficiency anemia, which is linked to lower developmental scores in childhood. Formula is fortified with iron at levels that match what a growing baby needs, making it irreplaceable during the first year.
There’s also an allergy consideration. A younger infant’s gut lining is more permeable to large protein molecules. As the intestinal barrier matures toward the end of the first year, the risk of developing a cow’s milk protein allergy from direct exposure drops.
What Your Baby Should Be Eating First
Stopping formula at 12 months only works if your baby is eating a solid, varied diet by then. That transition happens gradually over the second half of the first year. Most babies start with single-ingredient purees (avocado, peas, banana, squash) around six months. By about nine months, they should be handling thicker textures and small finger foods like shredded meat or soft pieces of fruit and vegetables. By 12 months, the goal is three meals a day with small snacks in between, covering proteins, grains, fruits, and vegetables.
If your baby is still mostly relying on formula at 11 months and barely touching solids, that’s worth addressing before you make the switch. Milk after 12 months is a supplement to food, not a replacement for it. Some babies take 10 to 12 tries before accepting a new food, so persistence matters more than perfection.
How to Make the Switch
You don’t need to swap formula for milk overnight. A gradual transition over one to two weeks is easier on your baby’s taste buds and digestion.
If your baby takes to cow’s milk easily, start by offering a 2- to 4-ounce serving of milk for every two or three servings of formula. Over the next week, increase milk servings and decrease formula servings until formula is gone entirely.
If your baby resists the taste of plain milk, try mixing it into prepared formula. Start with a ratio of about 3 ounces formula to 1 ounce milk in a 4-ounce bottle. Gradually shift the ratio over several days, adding more milk and less formula until the bottle is all milk. Always mix the milk into already-prepared formula rather than adding it to dry powder.
How Much Milk Per Day
Once your toddler is fully on cow’s milk, aim for 16 to 24 ounces per day. That range provides enough calcium and fat for bone and brain development without crowding out solid foods. Going over 24 ounces is where problems start: too much milk fills a toddler up, leaving less appetite for iron-rich foods like meat, beans, and fortified cereals. Over time, that pattern can lead to iron deficiency.
Use whole milk (not reduced-fat or skim) until age two. Toddlers need the fat content for brain development.
Vitamin D After Formula Ends
Formula is fortified with vitamin D, so while your baby drinks it, they’re covered. Once you switch to cow’s milk, the math changes. Children between 12 and 24 months need 600 IU of vitamin D daily. A cup of fortified whole milk contains about 100 IU, so even 2 to 3 cups a day won’t fully close the gap. Many pediatricians recommend continuing a vitamin D supplement after the switch, especially if your child gets limited sun exposure.
Skip Toddler Formula
Walk down the formula aisle and you’ll see “Stage 3” or “toddler formula” products marketed for children 12 months and older. The American Academy of Pediatrics has called these products “unnecessary and potentially harmful to young children,” noting that their popularity is driven largely by misleading advertising rather than any nutritional advantage. For a healthy toddler eating a varied diet, whole cow’s milk does the job at a fraction of the cost.
If Your Child Can’t Drink Cow’s Milk
For toddlers with a confirmed cow’s milk allergy or lactose intolerance, fortified soy milk is the closest nutritional match. A standard serving of soy milk provides comparable protein (about 6 to 7 grams per cup) and similar calories to whole cow’s milk, especially when fortified with calcium and vitamin D. Look for versions with no added sugar.
Other plant milks fall short in important ways. Almond milk provides very little protein or fat. Rice milk is similarly low in both. Oat milk offers slightly more fat but still delivers only about a third of the protein found in cow’s milk or soy milk. If your toddler drinks one of these alternatives as their primary milk, they’ll need to make up the missing protein and fat from other foods. For any plant-based option, choose one that’s fortified with calcium and free of added sugars.
If your child has multiple food allergies or you’re unsure which alternative fits their diet, a pediatrician or dietitian can help you map out a plan that covers all the nutritional bases without formula.