Sleep sack TOG calculator: which TOG at which room temperature?
The TOG rating tells you how warm a baby sleep sack is – and the right value depends solely on the room temperature in the bedroom. Simply set the temperature below: the calculator immediately shows you the right TOG rating and what your baby should wear underneath.
In short: from 24 °C ≈ 0.5 TOG · 20–24 °C ≈ 1.0 TOG · 16–20 °C ≈ 2.5 TOG · below 16 °C ≈ 3.5 TOG. In the UK, keep the bedroom at 16–20 °C (NHS). In the US there is no set number: keep the room comfortable for a lightly dressed adult (AAP). When in doubt, slightly too cool rather than too warm.
What does TOG mean?
TOG stands for Thermal Overall Grade and is a measure of the thermal insulation of fabrics. The higher the TOG rating, the warmer the sleep sack keeps your baby. Because a sleep sack replaces loose blankets, which don't belong in the crib, the right TOG rating makes sure your baby neither gets cold nor overheats.
TOG calculator
Slide the room temperature – read off the right TOG rating & clothing underneath.
Chart: TOG rating by room temperature
For everyone who prefers to look it up – the same recommendations as an overview:
| Room temperature | TOG rating | Clothing underneath |
|---|---|---|
| from 24 °C | 0.5 TOG · summer | Just a short-sleeve bodysuit |
| 20–24 °C | 1.0 TOG · spring and autumn | Long-sleeve bodysuit or thin sleepsuit |
| 16–20 °C | 2.5 TOG · all year | Bodysuit + sleepsuit |
| below 16 °C | 3.5 TOG · winter | Bodysuit + sleepsuit, possibly thin socks |
Look it up the other way round: which TOG for which temperature?
Most sleep sacks carry their TOG rating on the label. If one is already in the wardrobe, this is where you read off the room temperature it fits.
| TOG rating | Matching room temperature | Clothing underneath |
|---|---|---|
| 0.5 TOG · summer | 24 to 27 °C | Just a short-sleeve bodysuit |
| 1.0 TOG · transition | 20 to 24 °C | Long-sleeve bodysuit or thin sleepsuit |
| 2.0 TOG | 18 to 21 °C | Bodysuit and sleepsuit |
| 2.5 TOG · all year | 16 to 20 °C | Bodysuit and sleepsuit |
| 3.5 TOG · winter | below 16 °C | Bodysuit and sleepsuit, thin socks if needed |
At 25 or 26 °C the 0.5 TOG sleep sack still applies. If it gets warmer than that, a bodysuit alone is enough for many babies. Between two steps, take the thinner one and check at the neck.
Safety & safe sleep
What should my baby wear in the sleep sack?
The principle: the warmer the room, the less underneath. From 24 °C a short-sleeve bodysuit is enough, between 20 and 24 °C a long-sleeve bodysuit or a thin sleepsuit, below 20 °C you combine bodysuit and sleepsuit. If it's cool below 16 °C, thin socks help as well. Make sure the sleep sack fits well: the neck opening must be tight enough that the head can't slip inside.
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Frequently asked questions
What does TOG mean?
TOG stands for Thermal Overall Grade and measures thermal insulation. The higher the value, the warmer the sleep sack: 0.5 TOG for summer, 1.0 TOG for the transition seasons, 2.5 TOG for all year, 3.5 TOG for winter.
Which TOG at 18, 20 or 24 °C?
At ~18 °C a 2.5 TOG sleep sack, at ~20 °C a 1.0–2.5 TOG sleep sack, from 24 °C a thin 0.5 TOG summer sleep sack.
What should my baby wear in the sleep sack?
From 24 °C just a short-sleeve bodysuit, 20–24 °C a long-sleeve bodysuit or thin sleepsuit, below 20 °C bodysuit + sleepsuit. No hat, no loose blanket.
From what age can I use a sleep sack?
From birth, as long as the size fits: the neck opening must be tight enough that the head can't slip in. The sleep sack replaces loose blankets in the crib.
What temperature is a 2.5 TOG sleep sack for?
A 2.5 TOG sleep sack is considered right for a room temperature of 16 to 20 °C. A bodysuit and a sleepsuit underneath are enough. If the room is warmer than 20 °C, a 1.0 TOG sleep sack fits better.
How many TOG at 25 or 26 degrees?
At 25 to 27 °C a thin 0.5 TOG summer sleep sack is considered right, with just a short-sleeve bodysuit underneath. Above 27 °C a bodysuit without a sleep sack is enough for many babies. Check at the neck whether it is too warm.
More dressing guides
General guidance, not medical advice. When in doubt, ask your paediatrician or midwife.
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Sources: Safe sleep and TOG values: The Lullaby Trust, the UK safer-sleep charity; room temperature in the UK: NHS; clothing layers and room temperature in the US: American Academy of Pediatrics (AAP) and NICHD Safe to Sleep; clothing in the car seat: ADAC, German automobile club, child seat guidance; overheating and the neck check: German Professional Association of Pediatricians (BVKJ).