What TOG Sleep Sack for My Baby? A Room-Temp Guide

TOG is a measure of warmth, nothing more. A 0.5 TOG sack is light, a 2.5 TOG sack is for cold rooms. The whole job is matching the TOG to your nursery temperature, then dressing your baby underneath to suit. This guide gives you the chart in plain numbers, plus how to tell if you got it right.

What TOG actually means

TOG stands for Thermal Overall Grade. It is a textile rating for how well a fabric holds heat. You will see it on duvets and, increasingly, on baby sleep sacks. A higher number means a warmer item.

That is the entire concept. A sleep sack is a wearable blanket, and the TOG tells you roughly how much warmth it provides. It does not tell you what temperature your room should be, and it does not change based on your baby's size. It is just the warmth of the sack itself.

Sleep sacks for babies usually come in a few standard weights:

• 0.5 TOG, light, for warm rooms
• 1.0 TOG, the middle weight, for average rooms
• 2.5 TOG, heavy, for cold rooms

Some brands also sell a 3.5 TOG for very cold nurseries and a near-zero 0.2 TOG for hot weather, but the three above cover most homes most of the year.

Here is the part that matters. The TOG number is only useful next to two other things: your room temperature, and what your baby wears under the sack. Get those three working together and your baby is comfortable. Miss one and they are too warm or too cold.

TOG chart by room temperature

Use a thermometer in the nursery. A guess is not good enough, because the difference between a warm room and a hot one is the difference between the right sack and an overheated baby.

Find your room temperature in the chart, then match the TOG and the layers underneath.

Treat the chart as a starting point, not a rule. Babies run a little warmer or cooler than each other, and brands cut their sacks slightly differently. After a night or two you will learn whether your baby needs a touch more or less. Adjust the layers underneath before you swap the whole sack.

One note on the overlap rows. Where the chart shows a range, pick the lower TOG if your room sits at the warm end of the band, the higher TOG if it sits at the cool end.

How to dress your baby under a sleep sack

The sleep sack is one layer of the system. What goes under it is the part you adjust night to night.

The rule of thumb most parents use: dress your baby in one more layer than you would be comfortable sleeping in. The sleep sack counts as that extra layer, so what goes underneath is usually just a bodysuit, sometimes with footed pajamas in a cooler room.

Underneath the sack, follow the chart. Diaper-only for a hot room. A short-sleeve bodysuit for an average one. Long sleeves and footed pajamas as the room gets colder.

A few things to keep off your baby for sleep. No hats indoors. A baby releases heat through the head, and a hat during sleep raises the risk of overheating, which is why Safe to Sleep advises against head coverings in the sleep space. Skip loose blankets too. The sleep sack replaces them. The whole point of a wearable blanket is that nothing loose goes in the crib.

If your sack has a swaddle feature for a young newborn, the same logic holds, with one extra rule: stop using the swaddle wings at the first sign of rolling and switch to the arms-free sack.

Signs your baby is too warm or too cold

You do not have to guess. Your baby will tell you, and so will a quick touch test.

Check the chest or the back of the neck. Those spots reflect core temperature. Do not judge by the hands or feet. A baby's hands and feet run cool and a little bluish even when the rest of them is perfectly warm, so cool hands alone are not a sign of a cold baby.

Signs your baby is too warm:

• Chest or neck that feels hot and damp
• Sweaty or damp hair
• Flushed, red cheeks
• Breathing faster than usual
• Restless, fussy sleep

Signs your baby is too cold:

• Chest, back, or tummy that feels cool to the touch
• Pale skin

Overheating gets the more attention here for a reason. It is a recognized risk factor for sudden infant death syndrome, and the American Academy of Pediatrics advises against dressing a baby too warmly for sleep. When you are unsure, it is safer to go a little cooler than a little warmer. Drop a layer underneath, or step down a TOG, and check again.

Which TOG to buy first

If you are buying one sack, buy a 1.0 TOG.

It covers the room range most homes sit in for the bulk of the year, the common 69 to 73 degree band. From that single sack you can dress up or down with layers underneath to handle a fair range of nights.

Add a second sack once you know how your nursery behaves across seasons. A 0.5 TOG for summer, or a 2.5 TOG for a genuinely cold winter room. Buy that second one when the season actually calls for it, not all at once.

When you shop, look for the TOG printed clearly on the label so you are never guessing what you own.

The Kyte Baby sleep bag is one example that prints the TOG plainly on the label and sells the same sack in more than one weight, which makes it straightforward to match to your room. It is on the expensive side. For a full comparison of sleep sacks across price points, see our best sleep sacks for newborns roundup.

One last word. These numbers are a guide, and your baby is the real thermometer. If something feels off, or you are not sure what your baby should wear to sleep, ask your pediatrician.