Most babies should stay on formula until 12 months of age, then transition to whole cow’s milk. That 12-month mark isn’t arbitrary. Before that age, a baby’s kidneys and digestive system aren’t ready to handle cow’s milk as a primary drink, and formula provides nutrients that cow’s milk simply doesn’t.
Why 12 Months Is the Standard Cutoff
Infant formula is designed to mimic breast milk’s nutritional profile, with the right balance of iron, fats, vitamins, and proteins for a developing baby. Cow’s milk, by contrast, contains too many proteins and minerals for a young baby’s kidneys to process. Before 12 months, whole cow’s milk can actually cause microscopic intestinal bleeding, increase the risk of iron deficiency, and fail to deliver the nutrients a baby needs for healthy brain and bone development.
At 12 months, your baby’s digestive system has matured enough to handle cow’s milk. Their diet has also expanded to include solid foods that fill nutritional gaps. This combination makes the switch both safe and practical.
How Much Formula Babies Need by Age
Formula intake changes significantly over the first year as solid foods enter the picture. Here’s a rough guide to what most babies drink per day:
- 6 to 7 months: 5 to 7 ounces per feeding, about 5 to 6 times a day
- 8 to 9 months: 6 to 7 ounces per feeding, about 4 to 6 times a day
- 10 to 12 months: 6 to 7 ounces per feeding, about 3 to 4 times a day
As your baby eats more solid food, formula naturally takes up a smaller share of their total calories. But it remains essential through that first year because solids alone don’t provide enough iron, fat, or vitamin D for an infant.
How to Make the Switch to Cow’s Milk
You don’t need to swap everything overnight on your baby’s first birthday. A gradual transition over one to two weeks is easier on both of you. If your baby takes to cow’s milk easily, start by offering a small 2- to 4-ounce serving of whole milk for every two or three servings of formula. Over the next week, increase the milk servings and decrease the formula until the switch is complete.
If your baby isn’t a fan of the taste, try mixing the two together. Prepare a bottle of formula as usual, then add a small amount of whole milk. In a 4-ounce bottle, for example, start with 3 ounces of formula and 1 ounce of milk. Gradually shift the ratio over several days until the bottle is all milk. The key is adding milk to already-prepared formula rather than mixing it with dry powder.
Premature Babies May Need Formula Longer
The 12-month guideline applies to full-term infants. Babies born early often follow a different timeline based on their “corrected age,” which is calculated from their original due date rather than their actual birth date. Premature infants typically stay on fortified breast milk or specialized preterm formula for at least 6 months corrected age. Babies born very early or those with poor growth may need to continue until 12 months corrected age to support adequate catch-up growth.
A preemie who catches up quickly can sometimes switch to standard formula around 48 to 52 weeks of age, provided their weight and length are tracking at or above the 25th percentile for corrected age. Your pediatrician will guide this timing based on your baby’s individual growth curve.
Do Toddlers Need Toddler Formula?
Walk down the formula aisle and you’ll see “stage 3” or “toddler” formulas marketed for children over 12 months. For most healthy toddlers, these aren’t necessary. Once your child turns one, plain whole cow’s milk (or a fortified unsweetened dairy alternative) paired with a varied diet of solid foods covers their nutritional needs. Toddler formulas are significantly more expensive than milk and are largely a marketing category, not a medical recommendation.
That said, toddler formulas can serve a purpose for children with specific dietary restrictions, allergies, or growth concerns. If your child can’t tolerate dairy or is an extremely picky eater, a pediatrician may suggest one as a bridge.
Transitioning Off the Bottle Too
The shift away from formula is also a good time to move away from bottles. Ideally, you’ll have introduced a cup around 6 months, and the goal is to phase out bottles entirely between 12 and 18 months. Children who drink from bottles well into their second year face a higher risk of tooth decay, since milk or formula pools around teeth during prolonged sucking. Extended bottle use can also affect tooth alignment and even delay speech development, because the muscles used for clear speech need practice with open-cup drinking.
By around age 2, drinking from an open cup is the healthiest option for your child’s teeth and oral development. Sippy cups are fine as a stepping stone, but they shouldn’t become a long-term replacement for the bottle.
Breast Milk Follows a Different Timeline
Formula and breast milk aren’t interchangeable in terms of recommended duration. The World Health Organization recommends exclusive breastfeeding for the first 6 months, then continued breastfeeding alongside solid foods up to age 2 or beyond. Unlike formula, breast milk adapts its composition as a child grows, so there’s no equivalent 12-month “stop” recommendation. If you’re breastfeeding and supplementing with formula, the formula portion can stop at 12 months while breastfeeding continues as long as you and your child choose.