The general rule for dressing a newborn is one layer more than you’d wear comfortably in the same environment. Newborns can’t regulate their body temperature well, so they lose heat quickly in cool conditions and overheat easily when overdressed. Getting it right comes down to choosing the right fabrics, layering for the temperature, and avoiding a few common safety hazards.
The One-Layer Rule
If you’re comfortable in a t-shirt, your newborn likely needs a t-shirt plus a light layer on top, like a cotton onesie under a sleep sack or a thin cardigan. If you’re wearing a sweater, add a sweater-weight layer to your baby’s outfit too. This simple formula works for most everyday situations, indoors and out.
To check whether your baby is dressed right, feel the back of their neck or their chest. Warm skin means they’re comfortable. Sweating or hot skin on the chest are signs of overheating, which is a bigger concern than being slightly cool. Cool hands and feet are normal in newborns and don’t necessarily mean they need more clothing.
Choosing the Right Fabrics
Cotton is the classic choice for newborn clothing because it’s soft, widely available, and breathable. It does have one downside: cotton absorbs moisture and holds it against the skin rather than pulling it away, which can leave your baby feeling clammy in warm or humid conditions.
Bamboo fabric is roughly 20% more breathable than cotton and stays about 2 to 3 degrees cooler against the skin. Its fibers contain tiny micro-gaps that let air circulate, and it wicks sweat outward to evaporate instead of trapping it. Bamboo also offers natural UV protection around UPF 50+, compared to cotton’s UPF 5 to 10. Muslin is another good option, especially for swaddle blankets, because its open weave dries fast and breathes well.
Avoid polyester and other synthetic fabrics against a newborn’s skin. They trap heat, don’t breathe well, and are more likely to irritate sensitive skin.
Dressing for Sleep
For safe sleep, newborns should wear a fitted onesie or sleeper with no loose blankets in the crib. A wearable blanket (sleep sack) is the safest way to add warmth. Sleep sacks are rated by TOG, a measure of thermal resistance, and the right one depends on your room temperature:
- 0.2 TOG: 75°F to 81°F (warm rooms or summer)
- 1.0 TOG: 68°F to 75°F (typical indoor temperature)
- 2.5 TOG: 61°F to 68°F (cooler rooms)
- 3.5 TOG: below 61°F
Most homes kept around 68°F to 72°F call for a 1.0 TOG sleep sack over a long-sleeved onesie. In warmer months, a short-sleeved bodysuit with a 0.2 TOG sack, or even just a onesie alone, is often enough.
Hip-Safe Swaddling
If you swaddle your newborn, keep the arms snug but leave room around the hips and legs. A baby’s legs should rest in a natural “froggy” position, with hips slightly bent and knees apart. Swaddling that forces the legs straight and pressed together can stress the hip joint and increase the risk of developmental hip dysplasia. Look for swaddles designed with a wide pouch or sack at the bottom that lets your baby bend and kick their legs freely.
Working Around the Umbilical Cord Stump
Until the cord stump falls off (usually within the first two weeks), dress your baby in loose-fitting outfits that don’t pull on it. Tight waistbands can tug at the stump and cause irritation or bleeding. Fold your baby’s diaper below the stump so it stays dry and exposed to air. Some newborn-sized diapers come with a small cutout at the front for exactly this purpose. Skip belly bands, binders, or anything taped over the area.
Getting the Right Size
Newborn-sized clothing typically fits babies 5 to 8 pounds. If your baby is born at 8 pounds or more, they may skip newborn sizes entirely and go straight into 0 to 3 month clothing, which fits up to about 12 pounds. It’s worth having a few outfits in each size on hand before the birth, since you won’t know the exact weight until delivery day. Slightly too big is fine and more comfortable than too snug. Avoid anything that restricts movement around the hips, legs, or neck.
Dressing for the Car Seat
Puffy coats and thick snowsuits are unsafe in a car seat. The bulk compresses on impact, creating slack in the harness and reducing its ability to hold your baby securely. The National Highway Traffic Safety Administration recommends lightweight fleece layers instead of puffy materials so the harness fits snugly against your baby’s body. For extra warmth, buckle your baby in first, then drape a blanket over the harness or place a coat on backwards over the straps.
Sun and Heat Protection
Sunscreen isn’t recommended for babies under 6 months, so clothing is your primary defense against UV damage. Dress your baby in lightweight, long-sleeved shirts and pants when you’ll be outdoors. A wide-brimmed hat protects the face, ears, and neck. Keep your baby in the shade as much as possible, using a stroller canopy or umbrella when natural shade isn’t available.
In hot weather, a single layer of lightweight, breathable fabric is usually enough. A short-sleeved onesie or even just a diaper works indoors if the temperature is above 75°F. Watch for flushed skin, rapid breathing, or fussiness, all of which can signal your baby is too warm. In very hot conditions, bamboo or muslin fabrics offer better cooling than cotton.
Cold Weather Layering
In cold weather, think in layers rather than one heavy outfit. A base layer (onesie or bodysuit), a middle layer (fleece or knit), and an outer layer (bunting bag or coat) gives you flexibility to add or remove clothing as you move between indoors and outdoors. Mittens, socks, and a hat that covers the ears round out the outfit, since newborns lose a significant amount of heat through their heads and extremities.
Remove outer layers as soon as you come inside or get into a warm car. Overheating is a greater risk than being slightly underdressed, and it’s easier to add a blanket than to cool down an overheated baby who’s buried in layers.