The answer depends on whether you mean five months pregnant or a five-month-old baby outside the womb, and both are common searches. At five months of pregnancy (around 20 weeks), your baby is roughly the size of a grapefruit, measuring about 6⅓ inches from head to rump and weighing around 11 ounces. A five-month-old infant, on the other hand, typically weighs between 13 and 18 pounds and measures 24 to 27 inches long. Here’s what to expect at each stage.
At Five Months Pregnant
By the 20-week mark, your baby has grown from a barely visible cluster of cells into a recognizable little person. Crown to rump (not counting the legs), the fetus measures about 6⅓ inches and weighs roughly 11 ounces, or just under three-quarters of a pound. A grapefruit is the go-to size comparison at this stage, and it’s surprisingly accurate in both weight and circumference.
This is the halfway point of pregnancy, and growth is accelerating. Your baby’s limbs are fully formed, eyebrows and eyelids are developing, and you’re likely feeling kicks and rolls for the first time (or noticing them more clearly if you felt flutters earlier). Over the next few weeks, your baby will start putting on fat and muscle rapidly, roughly doubling in weight by the end of the second trimester.
A Five-Month-Old Infant
If your baby is already born and five months old, size varies quite a bit depending on birth weight, genetics, and feeding. On average, a five-month-old weighs around 15 to 16 pounds and is about 25 to 26 inches long, though healthy babies fall above and below those numbers. What matters more than hitting a specific weight is following a consistent growth curve on the chart your pediatrician uses.
Weight gain slows noticeably around this age. In the early months, babies pack on about 1 ounce (28 grams) per day. By four months, that drops to roughly 20 grams a day. By six months, many babies are gaining 10 grams or less daily. So if your baby’s weight seems to be climbing less steeply than before, that’s the normal pattern rather than a cause for concern.
What Your Five-Month-Old Can Do
Size is only part of the picture. At five months, your baby’s body is catching up to a brain that’s been wiring itself at breakneck speed, and you’ll notice new physical skills appearing quickly.
Most five-month-olds are rolling over in at least one direction, and many are working on rolling both ways. Arms and legs move with more purpose now, kicking and reaching rather than just flailing. Head control is much stronger: when placed on their stomach, most babies lift their heads confidently and may push up on their arms, mini push-up style. Some are already bearing weight on their legs when you hold them upright, though independent standing is still months away.
Hand coordination is developing fast too. Your baby can probably grasp a rattle, grab your finger, or pull a soft toy closer using a raking motion with their fingers. Sitting independently isn’t typical yet at five months, but many babies can stay upright for a few seconds when propped into a seated position, building toward sitting alone around six months.
Feeding to Support Growth
At five months, breast milk or formula is still the primary source of nutrition. Formula-fed babies at this age typically take 6 to 7 ounces per feeding, five to six times a day, which works out to roughly 30 to 42 ounces in 24 hours. Breastfed babies regulate their own intake but generally consume a similar total volume spread across more frequent sessions.
Some parents start introducing solid foods around this time, though many pediatricians recommend waiting until closer to six months, when babies can sit with support and show interest in food. Either way, solids at this stage are about exposure and practice, not calories. Milk remains the main fuel driving your baby’s growth through the end of the first year.
When Size Feels Off
It’s natural to compare your baby to others the same age, but the normal range is wide. A baby in the 15th percentile for weight is just as healthy as one in the 85th, as long as they’re growing steadily along their own curve. Pediatricians look for sudden drops or jumps across percentile lines rather than focusing on a single number.
Premature babies often track smaller for the first year or two, and their development is typically measured against their adjusted age (calculated from their due date, not their birth date). If your baby was born four weeks early, their five-month size and skills will more closely match a four-month-old’s, and that’s expected. Most preemies catch up to their peers by age two.