SleepSack TOG Ratings Explained: Which Weight for Which Season

Quick answer

Match the SleepSack TOG to the room your baby actually sleeps in, not to the calendar. For a typical 68–72°F nursery, TOG 1.5 over a light cotton sleeper is the most flexible starting point; go lighter (TOG 0.5) for warm rooms above roughly 75°F, and heavier (TOG 2.5) only when the room stays below about 68°F. If you are unsure, choose the lower TOG and add a layer of clothing rather than buying a warmer bag.

What a TOG rating actually measures

TOG stands for thermal overall grade, a laboratory measure of how much heat a garment traps. It is not a temperature setting and it is not a safety certification. Two bags with the same TOG can feel different if one uses muslin and the other uses thick terry, because fabric weight, airflow, and fit all change how warm your baby feels.

That is why a wearable blanket tog chart is only a starting point. The number tells you how much insulation the bag adds; your job is to add the right amount of clothing underneath so the total warmth matches the room. A TOG 1.5 bag over a short-sleeve cotton onesie lands in a different place than the same bag over a fleece footie.

Tog rating by room temperature: a simple working range

Use these ranges as a decision rule, then adjust for your baby. They assume a normal-weight, healthy baby sleeping in a room with still air and no extra blanket.

If your nursery swings between ranges overnight, pick the TOG for the warmer end and add clothing for the cooler hours. Overheating is the bigger risk to avoid, and it is easier to add a layer than to remove one from a sleeping baby.

• Above about 75°F (24°C): TOG 0.5, short-sleeve cotton bodysuit, no socks.
• 68–75°F (20–24°C): TOG 1.0–1.5, long-sleeve cotton sleeper or bodysuit plus light pants.
• 61–68°F (16–20°C): TOG 2.5, long-sleeve cotton sleeper, optional socks.
• Below about 61°F (16°C): TOG 2.5 plus warmer sleepwear, or warm the room instead of stacking bags.

What tog for baby sleep in summer vs winter

Summer and winter are less useful than room temperature, but the seasonal pattern is real. In summer, air conditioning and fans can push a room below the outdoor temperature, so a TOG 0.5 bag plus a cotton bodysuit often works while a TOG 1.5 bag becomes the choice in an air-conditioned room held near 70°F.

In winter, central heat usually keeps rooms warmer than people expect. Check the thermostat at 2 a.m. before buying a heavier bag. If the room holds near 68°F, a TOG 1.5 over a long-sleeve sleeper is often enough, and a TOG 2.5 is reserved for genuinely cool rooms or older homes that run cold.

How to check whether your baby is too warm or too cool

Do not judge by hands or feet, which run cool in babies even when they are comfortable. Slide a hand under the bag and feel the back of the neck and the chest. Warm and dry means the setup is working; sweaty, clammy, or flushed means remove a layer or drop to a lower TOG; cool with a mottled chest means add a layer.

Check about 30 minutes after your baby falls asleep, then again during the night for the first week after any change. If your baby wakes frequently, fusses, or has a damp neck, the room and the TOG are probably mismatched rather than the bag being wrong.

Fit rules that matter more than the TOG number

A bag that is too large can ride up over the face or let arms slip through the neck opening, and a bag that is too small restricts leg movement. Follow the manufacturer's size chart by weight and height, not by age alone, because two babies of the same age can differ by several pounds.

The neck opening should sit snug against the chest with no gap you can pull over the chin, and the armholes should keep arms inside without pinching. Stop using a wearable blanket once your child can unzip it or climb out of the crib, and switch to a toddler sleep bag or regular bedding only when the crib is converted.

Swaddle, SleepSuit, or wearable blanket: which stage are you in?

Newborns who still startle often do best in a swaddle with arms in. Once they show signs of rolling, swaddling must stop for safety, and that is the moment many families move to a transition product or a standard wearable blanket.

If your baby is fighting the swaddle but still needs containment, a transition suit can bridge the gap before a plain SleepSack. If your baby already sleeps well with free arms, skip the transition step and buy the wearable blanket TOG that matches your room.

Decision rules for choosing a TOG

• Start with the room, not the season: Put a thermometer in the nursery and read it at bedtime and again overnight. Choose the TOG for the warmest temperature the room reaches, then add clothing for cooler hours. If the room varies more than about 5°F, buy the lighter TOG and layer clothing.
• Pick one bag per temperature band: Most families need two bags: a TOG 0.5 for warm months or heated rooms, and a TOG 1.5 for the middle range. Add a TOG 2.5 only if your nursery regularly drops below about 68°F. Two well-chosen bags cover more nights than three overlapping ones.
• Adjust clothing before changing the bag: If your baby feels cool, add a long-sleeve sleeper or socks before moving to a higher TOG. If your baby feels warm, remove a layer before buying a lighter bag. Clothing is the fine adjustment; TOG is the coarse one.
• Recheck at every size change: A larger bag has more air space and can feel cooler at the same TOG, and a bag that no longer fits the neck opening is a safety issue regardless of warmth. Size up by weight and height, and retire any bag that gaps at the neck.

Products that fit these rules

• Swaddle 100% Cotton Muslin TOG 1.5: SleepSack Swaddle in 100% cotton muslin with TOG 1.5, a 3-in-1 design that can be worn arms in, hands to face, or arms out, with adjustable wings and a double zipper. The 3-in-1 design lets you keep the same TOG 1.5 warmth while changing arm position as your baby's startle reflex fades, so you may not need to buy a second bag just to transition out of swaddling.
• Baby Merlin's Magic Sleepsuit® 100% Cotton: Baby Merlin's Magic Sleepsuit in 100% cotton, designed to help babies move out of swaddling while calming the startle reflex. Useful when your baby has outgrown the swaddle but still needs a contained feeling; it is a transition layer, not a replacement for choosing the right TOG for your room.

Who this approach fits

Best for

• Parents setting up a nursery who want one clear rule for matching TOG to room temperature
• Families whose baby is transitioning out of a swaddle and needs to keep consistent warmth
• Caregivers in climates with both hot and cold seasons who want to buy only two bags

Not for

• Parents looking for a medical sleep or temperature recommendation; ask your pediatrician for that
• Babies who can unzip or climb out of a bag, who need a toddler sleep solution instead
• Anyone who wants a single bag to cover every room temperature without adjusting clothing