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What TOG Sleep Sack Does My Baby Need?
Short answer: choose a sleep sack for the temperature in the room where your baby will actually sleep, then use the manufacturer's chart for that exact sack. If the room is warm, choose a lightweight sack. TOG helps compare insulation; it is not a universal thermostat setting. The right size and avoiding overheating matter just as much as the number.
Start with the room, not the season
A January night can mean a well-heated condo; a June night can mean an air-conditioned nursery. Check the room temperature at bedtime and account for heating or cooling overnight. Health Canada's advice is plain: keep your baby warm, not hot. Sleepwear should suit the room, and a temperature comfortable for you will generally be comfortable for your baby.
Next, match the TOG and sleepwear underneath to the manufacturer's chart for that model. Charts can differ, so do not carry a temperature range from one brand to another. When in doubt, return to that product's instructions and favour avoiding overheating.
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What TOG can — and cannot — tell you
TOG is an insulation rating: in general, a higher number indicates more insulation and a lower number less. It cannot account by itself for every layer, room change, fit or product instruction. That is why a universal “this TOG equals this temperature” table can mislead. The useful combination is the actual room, the exact sack and its own guide.
Choose in that order: room temperature, product guide, then simple, fitted sleepwear underneath. Do not add a loose blanket because a sack feels light. Health Canada says a blanket is not needed with a sleep sack. Babies also do not need an indoor hat or outerwear for sleep.
Fit is a safety check
A sack can have the “right” TOG and still be wrong if its size is off. Follow the product's size guide. The neck and arm openings must not allow your baby to slip inside. A sack that is too large can create overheating or suffocation risks; one that is too small may restrict the hips and legs, especially if your baby rolls onto their tummy.
Fasten it as designed and check for loose snaps, zipper pulls, buttons or threads. Keep the nose and mouth clear and leave the hips and legs free. Do not size up simply for extra growing room.
Weighted and swaddle-style sacks
Do not use a weighted sleep sack, swaddle or blanket: Health Canada says these are not safe for babies. Health Canada also says there is no research to support the use of swaddle sleep sacks. If you choose one, swaddle loosely enough for breathing and free hip and leg movement, always place your baby on their back, and stop around two months — before rolling. Stop sooner if your baby shows signs of trying to roll.
Frequently asked questions
Is there one TOG chart for every brand?
No. Health Canada says to choose for the room and use a lightweight sack in a warm room; it does not publish a universal TOG-to-temperature table. Use the chart for the exact product instead.
Should I add a blanket over the sleep sack?
No. A blanket is not needed with a sleep sack. Keep the sleep space clear and choose the sack and fitted sleepwear for the room temperature.
Can I buy a bigger sack so my baby grows into it?
Not if your baby can slip inside it. Use the manufacturer's size guide now: the neck and arm openings should be secure, with room for the hips and legs to move.
When should I stop using a swaddle sleep sack?
Stop swaddling around two months, before your baby can roll, and sooner if they show signs of trying to roll. Swaddling is not safe when a baby is on their tummy.
Read Health Canada's full guidance, then explore our pyjamas and sleep sacks and bedding and swaddles.
This article provides general information, not medical advice. Follow the instructions for your exact product and the guidance of your health professional.