A Comprehensive Baby Sleep Sack Buying Guide

Every parent wants their baby to be warm, safe, and snug while they are napping in their crib. Medical experts advise parents to not put blankets or quilts in the baby crib, because they can increase the risk of sudden infant death syndrome (SIDS).

Parents still need a safe way to protect their infant from getting cold during the night, so they turn to the baby sleep sack. Below, you will discover a comprehensive buying guide to help you choose the perfect sleep sack for your precious bundle of joy.





When first shopping for a baby sack, you will discover an unlimited array of brands to select from with varying price tags. You should expect to pay a little more for name brand baby attire, because the quality and craftsmanship is superior compared to the knock off brand.


baby sleeping sack
Chart Size

The sleep sack is designed for preemies and infants up to 9 months of age. Of course, this does not mean that the child cannot use it for a longer time frame, but by this age, your child will be safe from SIDS. In order to get the perfect size, you may need to measure your infant’s height and weight.

Preemie – 17” or below or 5 pounds or below

Newborn – 18-20” or 5-8 pounds

0-3 Months – 20-23 ½” or 8-12 ½ pounds

3-6 Months – 24-25 ½” or 13-16.5 pounds

6-9 Months – 26-27 ½” or 17-20 ½ pounds

You must remember that the size chart will vary from brand to brand. Some brands may run a little smaller or larger than others, so be sure to keep this in mind, when you are shopping for a sleep sack.


sleeping sack

Most parents favor the polyester fabric over the other options, because it is capable of absorbing moisture to keep the infant’s skin dry throughout the night. This is very important, because your baby will perspire, when his body becomes overheated, just like you do.

Fleece is a synthetic fiber, just like polyester, it also absorbs moisture and keeps it from coming into contact with the baby’s skin. Both of these fabrics are perfect for the summer months, since they will keep your baby cool and dry throughout the night. If you keep the thermostat setting on a high temperature during the winter months, these fabrics will work perfectly during this season, as well.

Cotton is another favorable fabric that offers flexibility. This fabric is great for babies that can turn over and stretch out, since it will not restrict their movement. If you put your baby in a 100% cotton baby sack, you can rest assure that he/she will be comfortable all night long.

Sleeves or Sleeveless

You will find several different baby sack styles to choose from, sleeve or sleeveless. Many parents prefer the sleeveless design, because it offers better air circulation. This design is more suitable for the hot summer months, but this does not mean that they should be completely ruled out for the winter season. There are many dangers facing small infants, while they are in their crib and one of them is overheating.

A baby’s body can heat up extremely quickly and the parent would totally be oblivious, since they sleep in another room. This why the sleeveless style is so popular, because it can potentially decrease the risks of heat stroke, which is a life-threatening condition that can cause the body to shut down in a matter of minutes.

A fleece or polyester material is going to be your best option, if you are determined to purchase the sleeved design. As mentioned above, this synthetic material will absorb the excess perspiration and keep the baby’s body dry.

Appropriate Room Temperature

Most new parents may have questions concerning what to dress their baby in, when wearing a baby sack. Well, this will mostly depend on the temperature of the nursery. To be on the safe side, you should consider purchasing a small digital thermometer for the nursery, so you can monitor the temperature at all times.

The optimal temperature should range anywhere between 65-68 degrees Fahrenheit. If you keep the temperature within this range, you can dress the infant in an onesie, before placing him/her inside of the baby sack.

Safe Laundering

If you are determined to purchase a baby sack that is labeled machine washable, you should select the fleece or polyester fabric. This material will not shrink and can be safely placed in the washer and dryer, but note that the temperature setting should be on low heat. If you prefer the flexible cotton material, you should expect slight shrinkage and you may want to go up a size, just to play it safe.

Hand washing and line drying is going to be your best option, but most busy parents do not have the extra time to spare.

Zippered Design

All baby sacks are equipped with a zipper, because it offers fuss-free dressing. When shopping for baby attire with a zipper, you should stick with the well-known brands. Many of the knock off brands will come equipped with a zipper that can rub up against the infant’s body, break off, or the child may be able to get it into its mouth.

If the child gets the zipper wrapped around a tooth, it could potentially pull the tooth out of the gum socket.

Swaddle Design

The sleep sack swaddle is another very popular style, because it totally replaces blankets. This is basically a sleep sack with an adjustable swaddle that can be wrapped around the baby’s arms and body or just the body. This style is great for preemies and newborns, because they feel safer and rest better, when they are swaddled.

Once the child surpasses this stage, you can simply wrap the swaddle around the body, leaving the arms free. It is recommended to discontinue the swaddle as soon as the infant is able to turn over on its own.


Be sure to take the time to read this baby sleep sack buying guide, before heading out to the shopping mall. It will put you one step ahead in the task and help you sleep the perfect baby sack style for your little bundle of joy.



Tina is the owner of babysleep.help. She started this website after having sleeping problems with her own son so she knows how challenging it can be. Tina is also a gadget addict who loves to write about the latest baby products.

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