What is a TOG rating for babies and why is it important?

Every sleep sack and baby sleeping bag comes with a TOG number on the label. Most parents glance at it and move on, but that number is doing real work. It tells you exactly how much warmth the product provides, and choosing the right one for your baby’s room temperature is one of the simplest things you can do to support both safe sleep and comfortable sleep for your little one.

This guide explains what TOG means, how to use the temperature chart, how TOG needs to shift as your baby grows, and what to do when the number on your product doesn’t match the standard options.

What is a TOG rating?

TOG stands for Thermal Overall Grade. TOG is a standard unit of heat measurement. In plain terms, it helps you determine how well a piece of bedding or sleepwear will insulate your little one. The higher the TOG number, the warmer the product. If the material has a lower TOG rating, it means that it’s made from a cooler, more breathable material.

TOG is useful because you can’t always tell how warm a fabric would be just by touching it. The TOG rating is not only based on how thick the fabric is, but the material type, how much heat it retains, and the amount of warmth it provides.

Why is the TOG rating important?

When your little one is in the womb, their body temperature is regulated by that environment. After they are born, they cannot regulate their body temperature. They keep themselves warm through their body fat, ending up consuming a lot of energy and being tired. 

Babies also lose body heat rapidly, four times faster than adults. Since premature babies and babies born with low weight have low body fat, they struggle more with regulating their body temperature. 

Another interesting fact is that although babies can absorb heat very well, they don’t generate it easily. Babies are also more sensitive to temperature changes than adults. That’s why you must be attentive to their clothing and how much heat it’s going to retain. Hence, TOG ratings were introduced to sleep sacks, swaddles, and baby clothes to improve baby sleep safety. 

Another fabulous benefit? When babies are comfortable, they sleep longer, and that’s good news for everyone in the family.

How the TOG rating system for babies works

Most baby sleepwear is available across a range from 0.2 TOG up to 3.5 TOG. Think of it as a simple scale:

• 0.2–0.5 TOG: Very lightweight. A thin layer or covering only. For hot rooms and summer nights.
• 1.0 TOG: Light warmth. Good for mild temperatures and air-conditioned rooms that stay consistently cool.
• 1.9 TOG: Mid-range. Read more about it further in the blog.
• 2.5 TOG: The most widely used rating. Standard warmth for cool to cold rooms.
• 3.5 TOG: Maximum warmth. For very cold rooms only, with minimal base layering.

The TOG number accounts for the product’s insulating fill and fabric, tested under standardised conditions. 

Cradlewise Note: TOG measures only the product, what your baby wears underneath also contributes to their total warmth.

TOG rating chart: Room temperature guide

The table below uses the safe sleep room temperature range recommended by the American Academy of Pediatrics (64–72°F / 18–22°C) as its midpoint, with guidance for temperatures above and below.

TOG Rating Chart

Room Temp (°C)	Room Temp (°F)	Recommended TOG	Suggested Base Layer
Above 24°C	Above 75°F	0.2–0.5 TOG	Nappy only, or short-sleeve vest
21–24°C	70–75°F	0.5–1.0 TOG	Short-sleeve vest or bodysuit
18–21°C	64–70°F	1.0–1.5 TOG	Long-sleeve vest or light onesie
16–20°C	61–68°F	2.5 TOG	Long-sleeve vest + footed pyjamas
Below 16°C	Below 61°F	3.5 TOG	Long-sleeve vest + fleece pyjamas

Sources: Lullaby Trust dressing guidance and Sleep Foundation room temperature guidance 

Cradlewise Note: Always use a room thermometer to check the actual temperature at crib level. A thermostat reading can differ from the temperature where your baby sleeps, especially near air conditioning units or radiators.

TOG for preemies, newborns, babies, and toddlers

The temperature chart gives you the right starting point for any room. But your baby’s age and size affect how well they regulate their own body temperature.

TOG Chart by Age Group

Age Group	Key Consideration	TOG Adjustment	Special Note
Premature (born before 32 weeks) / low birth weight	Loses heat fastest; least body fat; poorest thermoregulation	Use upper end of chart range; keep room temperature 23–25°C (73.4–77°F)	Follow NICU discharge team’s specific guidance over general chart
Newborns (0–3 months)	Runs warmer than expected; cannot signal discomfort or move away from heat	Start at lower end of chart range for any given temperature	Never add hat indoors; overheating risk is highest at this stage
Babies (3–12 months)	Standard chart applies; increasing mobility means fit matters	Follow chart; ensure sleep sack fits snugly at neck and shoulders	Transition from swaddle to sleep sack when rolling begins
Toddlers (12 months+)	Better thermoregulators; kick covers off during sleep	Standard chart applies; sleep sack helps maintain consistent warmth	Can introduce blanket after 12 months if preferred — check TOG of blanket

Sources: PMC on neonatal thermoregulation in preterm infants

Premature and low-birth-weight babies

Premature and low-birth-weight babies have significantly less subcutaneous fat than full-term infants. Fat acts as insulation, without it, these babies lose body heat much faster and struggle to maintain a stable core temperature. 

For premature babies at home after NICU discharge: Always follow the discharge team’s specific guidance over a general TOG chart. As a baseline, keep the room at the warmer end of the safe range (23–25°C / 73.4–77°F minimum) and err toward a slightly warmer base layer than you would for a full-term baby.

Newborns (0–3 months)

Newborns tend to run warmer than parents expect. They also cannot signal discomfort, move away from heat, or kick off covers. This makes overheating risk highest in the newborn stage.

For any given room temperature, choose the lower end of the recommended TOG range for newborns, and never add a hat indoors during sleep.

Babies (3–12 months)

This is the stage where swaddles should be phased out. Once your baby shows signs of rolling, typically around 3–4 months, transition to a well-fitted sleeveless or arms-out sleep sack matters as much as the right TOG.

Toddlers (12 months+)

Toddlers are significantly better at thermoregulation than infants. They can also communicate discomfort and kick off covers if they’re warm. The TOG chart still applies, but the margin for error is larger.

A sleep sack remains useful for toddlers as they move a lot during sleep and tend to kick off loose blankets.

What are 1.9 TOG ratings for babies? 

If you’ve bought a sleep sack labelled 1.9 TOG and want to know what it is and when to use it: a 1.9 TOG sits between the standard 1.0 and 2.5 options and is designed for room temperatures of approximately 18–20°C (64–68°F).

• At 18–20°C: pair with a long-sleeve vest or light onesie underneath.
• At 20–21°C: pair with a short-sleeve vest or bodysuit.
• Below 18°C: the 1.9 TOG may be too light on its own. Add a warmer base layer or step up to 2.5 TOG.

The 1.9 TOG is a practical year-round option for homes where the room temperature sits consistently in the mild range. It’s particularly suited to air-conditioned rooms in warmer climates where overnight temperatures can drop below the daytime setting.

Quick check: If your baby’s chest feels hot or sweaty, the TOG is too warm. If it feels cool to the touch, add a layer or move up a TOG. Always check the chest or back of the neck as hands and feet naturally feel cooler and are not reliable temperature indicators.

What to do when room temperature changes overnight

Rooms often don’t hold a single temperature through the night. Central heating switches off at midnight. Outdoor temperatures drop after 3 am. Air conditioning cycles on and off. 

• Plan for the coolest point of the night, not the temperature at bedtime. If your room is 22°C at 7 p.m. but drops to 18°C by 4 a.m., choose your TOG for 18°C.
  
• Adjust the base layer, not the TOG. If the room is warm when you put your baby down but cools overnight, use a slightly lighter base layer under the same TOG sleep sack. Removing a layer mid-sleep disturbs the baby; choosing the right base layer at bedtime avoids this.
  
• Use a room thermometer with overnight logging. Many smart baby monitors track room temperature throughout the night, so you can see the actual range rather than guessing.
  
• For air-conditioned rooms, place the thermometer at crib height, not at head height or across the room. AC rooms can vary significantly by height and distance from the unit.

Cradlewise smart crib includes a built-in room temperature monitoring. See how it works.

TOG ratings across different baby sleep products

Parents often use sleep sacks, swaddles, blankets, and wearable blankets interchangeably, but the TOG logic applies differently to each.

TOG Ratings for Baby Sleep Products

Product Type	Typical TOG Range	Best Use	TOG Applies?
Sleep sack / sleeping bag	0.2–3.5	Newborns to toddlers; all-night sleep	Yes
Swaddle blanket	0.2–1.0	Newborns (0–4 months); bedtime routine	Yes — always use low TOG
Wearable blanket	0.5–2.5	Transitional stage; rolling babies	Yes — same as sleep sack
Quilt / duvet	Variable	Not recommended under 12 months	No — avoid for infants
Muslin wrap	~0.2	Warm weather, swaddling newborns	Effectively low TOG

Signs your baby is too hot or too cold

According to the American Academy of Pediatrics (AAP), your little one’s sleeping space should be clear of loose blankets, quilts, or duvets to reduce the risk of suffocation. TOG-rated wearable blankets and sleep bags keep babies warm without the risk that blankets pose. They help standardize your baby’s sleepwear, making it easier to control and monitor their sleep temperature.

Signs of overheating

• Chest feels hot or sweaty to touch
• Damp hair or flushed cheeks
• Rapid breathing or restlessness
• Unusually unsettled during what should be a settled sleep period

If you notice these: remove a layer of clothing, check the room temperature, and ensure the room is ventilated. Never cover your baby’s head with a hat indoors during sleep.

Keep in mind, babies are safer sleeping cooler than hotter. 

Signs your baby may be too cold

• Chest or back of neck feels cold to the touch (not hands or feet)
• Pale skin, baby seems lethargic or difficult to settle
• Frequent waking in the early hours, when room temperatures typically drop

If your baby seems cold: add a layer underneath the sleep sack rather than adding a blanket on top of it.

Conclusion

Choosing the right TOG is simpler than it looks once you have a thermometer and a basic chart. The core principle is consistent: match the warmth of the sleepwear to the coolest point of the night, dress the right base layer underneath, and check your baby’s chest rather than their hands to confirm they’re comfortable.

Age adds one layer of nuance: go slightly cooler for newborns, keep premature babies in a warmer room, and know that by toddlerhood your child’s thermoregulation is doing most of the work for you.

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Sources:

1. Did you know? Overheating is a recognised risk factor for SIDS (Sudden Infant Death Syndrome). PubMed Central. 2015. New Risk Factor for SIDS? Peaks in Cot Deaths Associated with Heat Waves.
2. Body fat in babies at birth. ScienceDirect. 2005. Brown Adipose Tissue. 
3. Did you know? Babies can’t shiver. PubMed Central. 2019. Brown Adipose Tissue in Human Infants. 
4. Signs your baby is too hot or too cold.  American Academy of Pediatrics. 2022. Sleep-Related Infant Deaths: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment.
5. Babies are safer sleeping cooler than hotter. The Lullaby Trust. How to dress your baby for sleep.