TOG Chart: Choosing the Right TOG to Dress Baby for Sleep

Sleep sacks help with infant sleep in another practical way beyond thermoregulation: because there's nothing loose to kick off during the night, a properly fitted sleep sack keeps the correct TOG in place until morning, which a loose blanket simply cannot do. Sleep sacks offer this consistency at any TOG you need, from the lightest hot-weather option to the heaviest winter-rated bag.

Choosing the right TOG sleep sack for every room temperature

Short answer: the warmer the room, the lower the TOG sleep sack and the lighter the layer underneath; below 60°F, increase the TOG rating rather than stacking multiple layers of baby sleepwear.

A simple rule of thumb: within the ideal 68-72°F range, a long-sleeve bodysuit under a 1.0 to 1.5 TOG sleep sack keeps your baby comfortable without overheating. Above 75°F, dress your baby with a lower TOG and remove a layer rather than adding a lighter sleep sack on top of a heavy one; a sleeveless bodysuit alone under a 0.5 TOG sleep sack is often enough to keep your baby warm without excess. Below 60°F, reach for the next TOG up (a 3.5 TOG sleep bag) rather than layering trousers, extra socks, or a hat, which add bulk without proportional warmth and are harder to check for overheating. Every baby is different, so treat the chart as a starting point and adjust the appropriate TOG rating using the neck check described further below.

During a heatwave, the goal is to bring the room back into the 68-72°F range rather than stripping baby down further in an already-hot room: a fan providing airflow across the room (never aimed directly at baby) or air conditioning set moderately helps keep the sleep space stable, which is far more effective for keeping baby comfortable than switching to an even lighter sleep sack in a room that's still too warm.

TOG for newborns vs. older babies

Short answer: the TOG chart above applies at any age, but newborns lose heat faster than older babies and are usually transitioned from a swaddle into a sleep sack once they start rolling, which changes how the same TOG rating is used in practice.

A newborn has a larger skin surface relative to body weight than an older baby or toddler, so their body temperature can shift faster in either direction, warranting slightly closer attention to the same TOG chart rather than a different one. In the first weeks, many parents combine the same TOG-rated sleep sack with swaddling for extra security; the research on swaddling below explains why a TOG-rated sleep sack alone is just as effective for warmth. Past 2 to 4 months, once baby starts rolling, the sleep sack takes over entirely from the swaddle at the same TOG rating for that room temperature. Older babies and toddlers moving into a wearable blanket for a bigger sleep space generally follow the identical TOG-to-temperature chart; the main practical difference is that a toddler who kicks off a blanket at night benefits even more from a properly TOG-rated sleep sack than a younger baby who moves less.

What the research says: overheating, swaddling, and safe sleep

Short answer: excessive thermal insulation from clothing and bedding is a documented risk factor, particularly for babies sleeping on their stomach, and swaddling shows no thermal advantage over a properly TOG-rated sleep sack.

Excess clothing and bedding is a known risk factor, modified by sleep position. A landmark study of SIDS cases found that a level of thermal insulation greater than what's needed to maintain body temperature increases risk, mainly among infants sleeping prone, and to a lesser extent among infants whose mothers smoked or who were mildly unwell (Ponsonby et al., 1996). The takeaway: placing baby on their back and avoiding overheating are two complementary precautions, neither interchangeable with nor sufficient without the other.

Thermal stress directly affects infant breathing and heart rate. A review of the literature on hyperthermia and heat stress in infants explains that excess heat can impair cardiovascular and respiratory function, with consequences including slowed heart rate or breathing pauses (Bach & Libert, 2022). The head plays a major role in an infant's heat loss, which is why hats should never be worn indoors once the room is within the recommended range.

Swaddling doesn't keep baby warmer than a sleep sack, and can increase overheating risk indoors. A randomized controlled trial in Mongolia, where outdoor temperatures are extreme, compared swaddled infants to infants sleeping in a sleep sack of equivalent thermal insulation. Result: no signs of cold stress were observed in the sleep sack group, and swaddling showed no thermal advantage over the sleep sack, even during the coldest hours of the night; in heated apartments, swaddling could even contribute to daytime overheating risk (Tsogt et al., 2016). The practical message: a correctly rated sleep sack is at least as effective as swaddling for keeping baby warm, without the added overheating risk.

How to tell if your baby is too hot

Short answer: touch the back of baby's neck or chest, never their hands or feet, which are naturally cooler and unreliable as indicators of whether baby is warm enough.

• Sweaty neck, flushed cheeks, damp hair: signs your baby is too hot. Remove a layer or switch to a lower TOG sleep sack.
• Warm, dry neck: baby is warm enough and the current TOG rating is right; no adjustment needed.
• Genuinely cold neck (rarer than most parents expect): add a layer or move to a higher TOG.
• Cool hands and feet: normal at any age; a baby's peripheral circulation naturally cools the extremities, and it isn't a reliable sign of overall body temperature.

A baby who is restless, sweating, or breathing faster than usual during sleep is worth checking against room temperature and sleep sack TOG first, before considering any other cause.

What should never be in baby's sleep space

Short answer: before age one, no loose blanket, comforter, pillow, crib bumper, or bulky stuffed toy belongs in the sleep space; a properly rated sleep sack is the only sleep layer recommended, regardless of room temperature.

• No loose blankets or comforters, even in cold weather: the associated risk (suffocation, slipping over the face) outweighs the thermal benefit, which a correctly rated TOG sleep sack already covers.
• No pillows or padded crib bumpers before age one, and no bedside sleeper attachments left unsecured.
• Swaddling should stop as soon as baby shows early signs of rolling over, typically between 2 and 4 months: once baby can roll onto their stomach, a swaddle that restricts arm movement for repositioning becomes a risk, independent of the temperature question addressed above.
• One layer if in doubt: it's easier to add a layer if baby is cold than to manage overheating that has already set in.

Quick tips for getting the correct TOG every night

Using a sleep sack instead of loose bedding is the single biggest change that makes baby's sleep environment safer, but a few extra habits help match the TOG to the room every time:

• Check the room thermometer before picking pajamas, not the weather app: the correct TOG depends on the temperature range inside, not outside.
• Keep a couple of sleep sacks on hand across a wider TOG range (a lighter one and a heavier one) rather than a single mid-weight option, so you always have the right TOG for your baby's room as seasons or heating settings change.
• When in doubt, size down the TOG, then check the neck: it's simpler to add a layer than to cool an overheated baby who is already dressed too warmly.
• Choose sleep sacks with a wide, unrestricted leg opening for safe hip movement, on top of picking the correct TOG for the temperature range.

FAQ

What is a TOG rating for baby sleep sacks?

TOG (Thermal Overall Grade) measures how much warmth a sleep sack traps: the higher the TOG rating, the warmer the sack. TOG ratings for baby sleep sacks typically range from about 0.2 (very light, for hot rooms) to 3.5-4 TOG (heavy, for cold rooms), and should be chosen based on the actual room temperature, not the season on the calendar.

What temperature should baby's room be at night?

Most safe-sleep guidance recommends keeping the room between 68 and 72°F (about 20-22°C) year-round. This room temperature, not the weather outside, is what should determine both the TOG rating of the sleep sack and the layer worn underneath.

How do I know if my baby is too hot or too cold?

Check the back of baby's neck or chest, not their hands or feet, which are normally cooler. A sweaty neck, flushed cheeks, or damp hair signal your baby is too hot; a genuinely cold neck signals baby needs another layer or a higher TOG. A warm, dry neck means baby is warm enough.

Can I use a blanket instead of a sleep sack?

No. Loose blankets, comforters, weighted blankets, pillows, and crib bumpers are not recommended in a sleep space before age one at any room temperature, regardless of how warm they might seem. A sleep sack rated for the room's TOG is the safer sleep alternative recommended by pediatric sleep guidelines.

Should I swaddle my baby to sleep, and until what age?

A randomized controlled study found no thermal advantage to swaddling over a properly TOG-rated sleep sack, even in cold conditions, and noted swaddling could increase overheating risk in heated indoor environments. Swaddling should also stop once baby shows early signs of rolling over, typically between 2 and 4 months, for safety reasons independent of temperature.

Key takeaways

• Room temperature (68-72°F / 20-22°C) determines the right TOG sleep sack, not the season on the calendar.
• Sleep sack TOG ranges from about 0.2 (hot rooms) to 3.5-4 (cold rooms), chosen by the degrees actually measured in the room, at any age from newborn to toddler.
• Excess thermal insulation from clothing and bedding is a documented SIDS risk factor, especially for babies sleeping prone.
• The neck, not the hands, is the reliable way to tell if your baby is too hot or too cold.
• Swaddling has no thermal advantage over a properly TOG-rated sleep sack and should stop once baby starts rolling over.
• No blankets, comforters, pillows, or crib bumpers before age one: a sleep sack remains the only recommended sleep layer.

Mothair is a wellness device designed to support parents' peace of mind during baby's nights and naps. It is not a medical device and does not diagnose, treat, or prevent any condition. For any question about dressing, sleep safety, or your baby's health, always consult your pediatrician or a qualified healthcare professional.