When you're breastfeeding, figuring out whether your baby's getting the right amount to eat is usually a pretty simple calculation — if enough's coming out in the diaper, enough's going in. With bottle-feeding, however, there's some math to do. After all, you'll want to know how much you can expect your little one to down, or how much formula will get the babysitter through the day — or you through the week. Which is why rough guidelines for formula amounts are so handy.

But these guidelines also come with some caveats. Bottle-fed babies, just like breastfed babies, know when they've had enough. But because formula delivery is regulated by caregivers, it's possible that parental pushing — prodding your little one to take those last few ounces — can result in your bottle-fed baby getting too much of a good thing.

So take your cues from your baby's hunger and feed to match her appetite instead of to a specified number of ounces. As long as your baby is gaining enough weight, is wetting and dirtying enough diapers, and is happy and healthy, you can be sure you're on target. Remember: Let your little one call the shots — and call it quits — when it comes to feedings.

Formula feeding guide

So given those caveats, you may still be wondering how much formula in general your baby needs. As a rule of thumb, infants under 6 months who haven't yet started solids should be taking 2 to 2½ ounces of formula per pound of body weight over a 24-hour period. In practice, that may work out to somewhere between 18 and 36 ounces per day, depending on your baby's size and mood.

So, if your baby weighs 10 pounds, that could translate to 20 to 25 ounces of formula a day; in a 24-hour period you'll be feeding your baby about 3 to 4 ounces every four hours.

But remember, every baby is different — bigger babies tend to drink more than smaller babies, and your baby's appetite may vary day-to-day and feeding-to-feeding. So treat these guidelines as rough approximations — there are no absolutes when it comes to how much formula to feed your little one at each meal — and always take your cues from your baby. If she becomes fidgety or easily distracted during a feeding, she's probably had enough. If she drains the bottle and starts smacking her lips for more, she might still be hungry.

Formula-feeding chart

Wondering just how much formula to give your baby? Use this formula-feeding chart as a guide.

formula-feeding chart, how much formula does my baby need

How much formula does a newborn need?

Your adorable bundle's tummy is tiny (the size of a fist — hers, not yours), so it's best to start slowly when it comes to feedings.

For newborns, offer just 1 to 3 ounces at each feeding every three to four hours (or on demand). Gradually up the ounces, adding more as the demand becomes greater, but never push a baby to take more than she wants.

How much formula should you feed your baby by age?

Your cutie will be taking in more formula at each feeding, anywhere from 3 to 7 ounces, depending on her age. Her stomach capacity has increased, too, which means she'll likely stretch out the time between feedings.

In general, here's what you can expect:

  • 2-month-olds will usually drink 3 to 6 ounces of formula every three to four hours. That adds up to 18 to 32 ounces of formula in around eight feedings total in a 24-hour period.
  • 3-month-olds will generally drink 4 to 6 ounces of formula around every four hours. That adds up to 24 to 36 ounces of formula in around six feedings total in a 24-hour period.
  • 4-month-olds will often drink 5 to 7 ounces of formula every four to five hours. That adds up to 24 to 32 ounces of formula in four to six feedings total in a 24-hour period.
  • 5-month-olds will typically drink 6 to 8 ounces of formula around five times per day. That adds up to 24 to 36 ounces of formula total in a 24-hour period.
  • 6-month-olds will usually drink 6 to 8 ounces of formula four to five times per day. That adds up to 24 to 32 ounces of formula total in a 24-hour period.

Have a serious sipper who consistently seems to want more than that? Discuss it with your doctor. The upper daily intake formula intake for babies 6 months and younger is 32 to 36 ounces per 24-hour period, according to the American Academy of Pediatrics (AAP).

Formula-feeding schedule

Now that you've got the amounts figured out, when should your little eater be drinking up? Early on, it's best to feed your newborn on demand whenever she is sending out hunger cues like lip smacking, rooting and finger sucking. As you get a sense of her appetite and natural rhythms over the course of a month or two, you'll be able to transition to more formal mealtimes.

Newborn formula-feeding schedule

Much as you might be longing for some predictability right now, newborns aren't typically ones to stick with a schedule for eating or sleeping.

Rather than do mealtimes by the clock or try to enforce nap or bedtimes, try to go with your little one's flow. You can offer an ounce or two of formula every two to three hours, or eight to 12 feedings within a 24-hour period. But those are more loose guidelines than hard rules. Ultimately, you'll want to feed your newborn on demand when she seems hungry.

Within a few months, she'll start to establish a rhythm that you can use as the basis for a feeding and sleeping schedule.

Can a baby eat too much formula?

Healthy babies, when allowed to drink (and eventually eat) to their appetites without any prodding by parents, will grow at the rate that's normal for them. If your little one's weight is increasing at a steady clip and following a familiar curve, there's no need to worry that she's overeating. But if your baby's bottle becomes the liquid equivalent of an all-you-can-eat buffet, there's a chance she can easily get too much.

Here are signs to look for that may indicate your baby is taking in more formula than she needs:

  • Frequent spit-ups. Overfeeding can lead to overflow in the form of excessive spit-up. Put too much in her little tummy, and it's bound to come back up.
  • Excessive weight gain. If your baby's weight seems to be consistently moving upward faster than her height, check with the doctor. She may be picking up too many pounds too quickly because she's taking in too much formula.

If your pediatrician tells you that your baby seems to be overeating, there are a few things you can do to slow down her formula intake (and the rate of weight gain):

  • Feed for the right reason. The right reason being because she's hungry. Not because she's unhappy, or because she's bored, or because she got a boo-boo, or because she's craving attention. Baby's recently fed but crabby? Offer comfort with a cuddle, not an extra feed. Baby's fussy after a meal? Consider that she may just need a burp, not a second serving.
  • Offer your baby a pacifier to satisfy the need to suck. Or help her find her yummy fist or fingers. Some babies just need extra sucking (not an extra bottle) between meals or after a feed.
  • Make sure you're not under-diluting the formula. Always check the label when you're mixing formula to make sure you're not inadvertently adding too little water — which can increase the calorie count per ounce considerably.
  • Ask the doctor if you can offer your baby water. Usually not recommended before solids are started at 6 months, a few sips of water could quench her thirst without filling her up. But don't over-dilute formula with water to cut down on her consumption of calories without a doctor's advice — this can lead to a sodium imbalance.

Figuring out feeding times can feel like a lot at first. In the beginning, try to follow your baby's lead and keep the general rules of thumb for feeding times and amounts in mind as helpful guideposts. (And if you have any questions, always ask the pediatrician.) Over time, the two of you will fall into a feeding rhythm and you'll get a sense for how much your little one needs to drink and when she's likely to expect a sip.