Baby Sleep Sack TOG Guide (2026) — A Pediatrician’s Chart

TOG (Thermal Overall Grade) tells you how insulating a sleep sack is. 0.5 TOG is for warm rooms (74–78°F), 1.0 TOG for room-temperature nurseries (69–73°F), and 2.5 TOG for cool rooms (61–68°F). Matching TOG to room temperature is the single most important step in preventing both overheating (a known SIDS risk) and cold-related waking.

Quick TOG chart

Safe sleep is always: back-sleeping, firm flat mattress, tight sheet, empty crib (no blankets, bumpers, or loveys until 12 months), and appropriate room temperature (68–72°F ideal).

Table of contents

• What TOG means
• How TOG differs from clothing weight
• The full TOG chart with layering
• Room temperature — how to measure it correctly
• Signs of overheating and how to check
• Signs your baby is too cold
• TOG by season
• Sleep sack safety rules
• When to stop using a sleep sack
• Best sleep sack brands by TOG
• Common mistakes
• Red flags — when to call your pediatrician
• Frequently asked questions
• About the author

What TOG means

TOG stands for Thermal Overall Grade — a UK textile standard that measures how much heat a fabric traps. Higher TOG = warmer. It was developed for bedding and adapted for infant sleep sacks so parents can match insulation to room temperature.

Common infant TOG ratings:

• 0.2 TOG — muslin, mesh, or lightweight cotton. Almost no insulation.
• 0.5 TOG — light cotton, single layer.
• 1.0 TOG — quilted cotton or bamboo, single filling layer.
• 2.5 TOG — quilted cotton with heavier filling.
• 3.5 TOG — heaviest, for the coldest rooms.

TOG measures the garment, not the baby. Two babies in the same 1.0 TOG sack in identical rooms can still overheat or feel cold based on what they wear underneath.

How TOG differs from clothing weight

A common mistake is treating TOG as a stand-alone rating. It is not — TOG is the insulation of the sack, and total warmth is TOG + clothing underneath + room temperature. If you upgrade a bodysuit to footed pajamas, you have effectively increased the warmth by roughly 0.5 TOG.

Use TOG as the base layer, then adjust underneath clothing to fine-tune.

The full TOG chart with layering

Never add a blanket over a sleep sack for extra warmth. Any loose fabric in the crib is an AAP-recognized suffocation and SIDS risk before 12 months. Increase TOG or layer under the sack instead.

Room temperature — how to measure it correctly

• Place a thermometer at crib level, not on a shelf or wall high up. Warm air rises; the temperature near the ceiling can be 3–5°F higher than at the crib.
• Take the reading at the time your baby sleeps, not at the warmest hour of the day.
• Aim for a bedroom range of 68–72°F (20–22°C) — the AAP-recommended safe sleep temperature.
• Avoid space heaters, hot water bottles, and heated mattresses in the nursery.

Modern digital nursery thermometers (many with a target-zone display) are worth the small cost. A room that “feels” 70°F to an adult can be significantly warmer to a swaddled or well-dressed baby.

Signs of overheating and how to check

Overheating is a documented independent risk factor for SIDS, and it is the most common dressing mistake I see in clinic. Check every night by touching the back of the neck or the chest (not hands or feet — those are always cooler and are not a reliable temperature signal).

Signs of overheating:

• Sweaty hair or damp neck
• Flushed cheeks or red skin
• Rapid breathing at rest
• Warm, sweaty chest and back
• Unusual restlessness with squirming to escape covers
• Waking earlier than usual, upset

If any of these are present, drop one full TOG level or remove a layer underneath. Confirm the room temperature.

Source: American Academy of Pediatrics, Safe Sleep Recommendations.

Signs your baby is too cold

Cold babies fuss and wake but rarely fall dangerously cold in a heated home. Look for:

• Cool chest and back (not hands or feet)
• Pale skin
• Waking every 60–90 minutes and settling as soon as picked up
• Persistent hiccups (mild cold response)

Add one TOG level or upgrade the underneath layer.

TOG by season

Summer. Most homes without central air run 74–78°F at night. Use 0.5 TOG or even 0.2 TOG (muslin sleep bag) with a short-sleeve bodysuit only.

Fall / spring transition. Highly variable. Keep 1.0 TOG on hand as the workhorse; switch underneath layers weekly as temperatures move.

Winter with heating. Central heat typically keeps nurseries at 68–72°F. 1.0 TOG with a long-sleeve footed pajama is the standard combination.

Winter with cool nursery. Older homes, rooms above garages, or drafty windows can drop into the low 60s. Use 2.5 TOG with a long-sleeve footed pajama.

Cold-climate winter (below 60°F). 3.5 TOG with layered footed pajamas. Consider a nursery-safe space heater with automatic shutoff placed at least 3 feet from the crib.

Sleep sack safety rules

• Correct size only. The neck opening must not fit over the baby’s head; the armhole must be snug enough that the baby cannot slip inside the bag.
• Two-way zipper (bottom-up) makes nighttime diaper changes possible without unzipping the whole bag.
• No hoods, ties, or drawstrings on any infant sleep garment.
• No swaddle sacks after rolling starts (usually 8–12 weeks). Move to a walking-arms-free sack.
• Never combine a sleep sack with a blanket in the crib.
• Wash before first use in fragrance-free detergent.
• Replace when small. A sack the baby can climb into becomes a hazard.
• Sleep sacks with weighted panels are not recommended by the AAP; the safest sacks are lightweight and unweighted.

When to stop using a sleep sack

• Rolling from back to front: stop using any sleep sack with the arms in (swaddle sack). Move to a walking sack or arms-out sleep bag.
• Standing in the crib (usually 8–12 months): most families continue sleep sacks; choose a walking-length sack.
• Climbing out of the crib (18–24 months): transition to toddler pajamas or a wearable blanket that allows walking.
• When the child asks for a blanket (usually 18–24 months): safe once the child is out of the crib and can move a blanket off their face.

Best sleep sack brands by TOG

All meet CPSC infant sleep garment safety standards. Woolino merino is naturally temperature-regulating and often needs less swapping across seasons.

Common mistakes

• Using 2.5 TOG in summer because it looks cozy. Overheats a baby fast.
• Reading TOG in isolation. Always factor in underneath layer.
• Checking hand or foot temperature. Both are almost always cool — not a warmth signal.
• Adding a blanket “just to be safe.” Blankets under 12 months are an AAP-recognized SIDS risk.
• Using a swaddle sack past first roll. Immediate hazard once rolling starts.
• Buying oversized to grow into. Baby slips inside — suffocation hazard.
• Skipping the room thermometer. Guessing room temperature is the leading cause of overheating.

Red flags — when to call your pediatrician

Call the same day for:

• Persistent sweating even at appropriate TOG
• Persistent cold body despite adequate layers
• New rash where the sleep sack contacts skin (possible allergy)
• Any breathing pauses, blue color, or difficulty rousing after sleep
• Fever with unclear cause (always evaluate infants under 3 months with any fever)

Frequently asked questions

What TOG sleep sack for 70°F room? A 1.0 TOG sleep sack with a short-sleeve bodysuit underneath, or a long-sleeve bodysuit if closer to 68°F.

What TOG for winter? 2.5 TOG for a nursery in the mid-60s, 3.5 TOG for a room under 60°F. Combine with a long-sleeve footed pajama.

Can you use a 2.5 TOG in summer? No — it will overheat most babies. Use 0.5 TOG for warm rooms (74–78°F) or 0.2 TOG for hot rooms (above 78°F).

Is 1.0 TOG safe year-round? 1.0 TOG is the workhorse for room-temperature nurseries (69–73°F). It is not safe in the mid-60s (too cold) or the mid-70s (too warm) without adjusting the layer underneath.

How do I know if my baby is overheating? Check the back of the neck or chest. Sweaty hair, flushed face, damp neck, or rapid breathing are overheating signs. Drop one TOG or remove a layer.

Should I dress my baby under a sleep sack? Yes. TOG is the sack only. Under it, dress the baby based on room temperature — short-sleeve bodysuit for warm rooms, long-sleeve footed pajamas for cool rooms.

Can I use a blanket instead of a sleep sack? No blankets under 12 months. AAP guidance is a bare crib with a wearable sleep sack. Blankets increase SIDS and suffocation risk.

When should I stop using a sleep sack? Most families stop between 18 and 24 months, once the child transitions out of the crib.

About the author

Dr. Zeeshan Salam, MD is a board-certified pediatrician and neonatologist. Learn more on the About page.

Medically reviewed: July 18, 2026 Last updated: July 18, 2026

Sources and further reading

• AAP HealthyChildren.org — Safe Sleep
• American Academy of Pediatrics — Safe Sleep Recommendations
• Consumer Product Safety Commission — Wearable Infant Blankets