Most babies stay on formula until 12 months of age, at which point they can switch to plain whole cow’s milk. This timeline applies to healthy, full-term infants who are also eating a varied diet of solid foods. The 12-month mark isn’t arbitrary: it’s the age when a baby’s digestive system and kidneys are mature enough to handle cow’s milk and when solid foods can supply the nutrients formula previously covered.
Why 12 Months Is the Cutoff
Before a baby turns one, cow’s milk poses real risks. It contains too many proteins and minerals for a baby’s kidneys to process efficiently. It can cause microscopic intestinal bleeding. And it simply doesn’t have the right balance of nutrients a baby needs during that first year, particularly iron, vitamin C, and essential fatty acids that formula is specifically designed to deliver.
Formula bridges the gap between birth and the point where a child can get adequate nutrition from regular food and milk. Between 8 and 12 months, babies still rely on formula for roughly 400 to 500 calories a day, which works out to about 24 ounces. The rest of their calories come from solid foods, which they typically start around 6 months. By 12 months, solids have become the primary source of nutrition, and formula’s job is essentially done.
How Formula Needs Change Month by Month
Newborns start small, taking just 1 to 2 ounces per feeding every few hours. By 2 months, most babies drink 4 to 5 ounces per feeding. Volume continues to climb until it plateaus around 6 to 8 ounces per feeding somewhere between 4 and 6 months.
Once solid foods enter the picture around 6 months, formula volume gradually decreases. Your baby won’t drop bottles overnight. Instead, solid meals slowly replace some of the calories that formula used to provide. By 8 to 12 months, the target is around 24 ounces of formula per day alongside three meals of solid food. That ratio keeps shifting toward food until, at 12 months, you can make the full switch.
How to Make the Switch to Milk
You don’t need to swap formula for cow’s milk in a single day. The CDC suggests starting by replacing one formula feeding with cow’s milk and working from there. If your baby resists the taste, you can mix equal parts whole milk and prepared formula, then gradually increase the milk ratio over a week or two. Children’s Hospital of Philadelphia notes that it’s fine to offer a small amount of whole milk, about an ounce in a sippy cup, starting around 11 months to ease the transition.
Once your baby is fully on cow’s milk, aim for 8 to 10 ounces per day as a minimum (especially if they’re also eating cheese, yogurt, or other dairy) and no more than 24 ounces per day. Too much milk can crowd out other foods and make it harder for your child’s body to absorb iron. Stick with whole milk until age 2, since toddlers need the fat for brain development.
This is also a good time to move away from bottles entirely. The goal is to transition to sippy cups or straw cups as soon after the first birthday as possible, which helps protect developing teeth and encourages self-feeding skills.
Do You Need Toddler Formula?
Walk down the formula aisle and you’ll see “stage 2” or “stage 3” toddler milks marketed for children 12 months and older. The American Academy of Pediatrics is clear on this: most toddlers don’t need them. These products are generally unnecessary, nutritionally incomplete compared to standard infant formula, and offer no advantage over regular cow’s milk for healthy children over 12 months. Many are also high in added sugar and cost significantly more than a gallon of whole milk.
For a toddler eating a varied diet that includes fruits, vegetables, grains, protein, and dairy, plain whole milk covers the same nutritional ground at a fraction of the price. Toddler formulas can safely be used as part of a varied diet, but they aren’t a substitute for real food and they aren’t an upgrade from cow’s milk.
When Some Babies Stay on Formula Longer
Certain situations call for extending formula use past 12 months. Premature babies often follow an adjusted timeline based on their corrected age rather than their birth date. Babies with milk protein allergies, metabolic conditions, or feeding difficulties may need a specialized formula longer. Children who aren’t yet eating a sufficient variety of solid foods by their first birthday may also benefit from continuing formula while their diet catches up. In these cases, the timeline is individualized rather than following the standard 12-month guideline.
Signs Your Baby Is Ready for the Transition
The switch from formula to milk isn’t just about hitting a birthday. Your baby should also be eating a range of solid foods reliably. By 12 months, most babies can sit independently, chew soft foods, drink from a cup with help, and eat three meals a day with snacks. They should be getting nutrition from multiple food groups, not just relying on formula and a few bites of cereal.
If your baby is turning one but still getting the vast majority of calories from formula and showing little interest in solids, focus on expanding their diet before rushing the milk switch. The 12-month milestone assumes a baby who has been building solid food skills since around 6 months, when most children show readiness signs like sitting with support, controlling their head and neck, swallowing food instead of pushing it out, and reaching for objects to bring to their mouth.