Swaddle vs Sleep Sack, Sizes and TOG
A swaddle wraps a baby's arms for the newborn weeks, a sleep sack leaves them free; both are sized by weight and length, and TOG says how warm they are.
By Amanda RoseContributing writer.
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The short answer
A swaddle wraps snugly around the body and holds the arms in, which can calm a newborn. A sleep sack (also sold as a wearable blanket or sleep bag) is a zip-up sack with armholes, so the arms stay free and the legs can move inside.
Most families use a swaddle first and move to a sleep sack once the baby starts to roll. Both replace a loose blanket in the crib, which the American Academy of Pediatrics (AAP) advises against.
Swaddle vs sleep sack
| Swaddle | Sleep sack | |
|---|---|---|
| Arms | Wrapped in (some styles free one or both) | Free, through armholes |
| Fit around the chest | Snug | Loose enough to move |
| Typical stage | Newborn weeks, until rolling starts | From birth or after swaddling, into the toddler years |
| Rolling baby | Stop using | Fine if it does not swaddle or compress |
When to stop swaddling
The AAP's parent site, HealthyChildren.org, says to stop swaddling as soon as a baby shows any sign of trying to roll over. Some babies start working on that as early as 2 months, so watch the baby rather than the calendar. The same advice applies to sleep sacks that compress the body or pin the arms. A sack that lets the baby move freely can be used as long as you like.
Other points from the same page:
- Always lay a baby on their back to sleep, swaddled or not.
- Keep the hips loose. Legs should be able to bend up and out; a tight wrap with straight legs can contribute to hip dysplasia. You should fit two or three fingers between the chest and the swaddle.
- Skip weighted swaddles and weighted sleep sacks.
- Watch for overheating: sweating, damp hair, flushed cheeks or fast breathing.
Sleep sack sizes
Sizes go by weight and length, not only age, and each brand draws the lines a little differently. Kyte Baby, for example, publishes these bands for its sleep bags:
| Size | Weight | Length |
|---|---|---|
| XS | 7 to 13 lb | 20 to 25 in |
| S | 14 to 20 lb | 22 to 27 in |
| M | 18 to 30 lb | 26 to 33 in |
| L | 28 to 42 lb | 33 to 40 in |
| XL | 38 to 50 lb | 37 to 47 in |
Kyte advises buying the size that matches the child's current weight and length rather than sizing up, with a snug fit at the neck and armholes so the sack cannot ride up over the face. Check the chart of the brand you are buying, since another maker's "Small" may cover a different range.
What TOG means in sleep sacks
TOG stands for thermal overall grade, a rating of how well a fabric holds warmth. A higher number is warmer. Sleep sacks commonly come in 0.5, 1.0 and 2.5 TOG. Kyte Baby matches them to room temperature like this:
| Room temperature | TOG |
|---|---|
| Below 70°F | 2.5 |
| 70 to 75°F | 1.0 |
| 75°F and up | 0.5 |
Adjust the layer underneath (a diaper only, a short-sleeved or long-sleeved bodysuit) before adding anything on top. Feel the back of the neck after a few minutes: sweaty means too warm.
Shopping on Wiki Shopping
Swaddles and sleep sacks sit with the rest of the nursery gear under baby products. Before you buy, compare the listing's size chart with your baby's weight and length, and look for the TOG rating in the product details.