How to Choose the Right TOG Sleeping Bag for Your Baby

Quick answer

Start with your nursery's typical overnight temperature, not the season on the calendar. A 1.0 TOG bag suits warm rooms around 24-27°C, 2.5 TOG is the everyday choice for roughly 20-24°C, and 3.5 TOG is for cold rooms below about 20°C. Buy one bag in the TOG that matches your most common room temperature, then add a second weight only if your nights swing widely.

Most parents buy a sleeping bag the way they buy baby clothes: by age and season. That is where the trouble starts. A bag that is too warm is a bigger problem than one that is slightly cool, because overheating is linked to sleep discomfort and, in the worst cases, to safer-sleep risks.

TOG is simply a warmth rating, similar in spirit to the tog rating on a duvet. It does not tell you how thick the fabric feels in your hand, and it does not replace a room thermometer. Read the rules below, check your nursery temperature for a week, and the right bag becomes an easy decision.

What the TOG rating actually tells you

TOG stands for thermal overall grade, a measure of how much heat a garment or bedding traps. Higher numbers mean more warmth. For baby sleep bags, the useful range is roughly 0.5 TOG for hot summer nights up to 3.5 TOG for unheated rooms in winter. The rating assumes your baby wears a normal base layer underneath, such as a cotton bodysuit or pajamas.

Two bags with the same TOG can feel very different because of fabric and construction. A muslin or lightweight cotton bag breathes more than a padded one, which matters in humid climates. This is why the number is a starting point, not the whole answer.

• Use a room thermometer near the cot, not a phone weather app for your city.
• Check the temperature at cot height, not on a shelf or windowsill.
• If you are between two TOG ratings, choose the lower one and add a layer underneath.

How to match TOG to your baby sleep bag temperature

The chart below is a working guide, not a medical rule. Most safe-sleep guidance suggests a room between roughly 16°C and 20°C for comfortable infant sleep, with lighter clothing in warmer rooms. If your nursery regularly sits above 24°C, you want a low-TOG bag and very little underneath.

The mistake to avoid is layering a thick bag with a thick sleepsuit. That combination is what pushes babies into overheating. Pick the bag first, then dress your baby for the difference.

• Around 24-27°C: 0.5-1.0 TOG bag, short-sleeve bodysuit or just a diaper.
• Around 20-24°C: 1.0-2.5 TOG bag, long-sleeve bodysuit or light pajamas.
• Around 16-20°C: 2.5 TOG bag, pajamas plus a bodysuit.
• Below 16°C: 3.5 TOG bag and warm pajamas, or warm the room instead.

Fit and size: the part most parents get wrong

A sleeping bag should fit the neck and armholes closely enough that your baby cannot slip down inside it, while leaving room at the bottom for legs to move. If you can pull the neckline over your baby's chin, the bag is too big. If the fabric pulls tight across the chest, it is too small.

Follow the manufacturer's height and weight range rather than age alone, because babies of the same age vary enormously. A bag that is too long can bunch around the face when your baby rolls, and a bag that is too short restricts hip and leg movement. When your baby is between sizes, size down for safety and check the neck opening first.

• Do the two-finger test at the neck: two fingers should fit, but not a whole hand.
• Check armholes for gaps that could let a shoulder slip through.
• Stop using the bag when your child can undo the zip or climb out of the cot.

Fabric, closures, and what to check before you buy

Look for a two-way zip so you can change a diaper without fully unwrapping your baby at 3 a.m. Check that the zip has a fabric guard at the top so it does not rub the chin. For warm rooms, muslin and light cotton move air better than dense quilted fabrics; for cold rooms, a quilted bag with a coated or tightly woven outer layer holds warmth longer.

Certification is worth a look if your baby has sensitive skin. GOTS-certified organic cotton means the fiber and processing meet a recognized organic standard, which reduces exposure to certain chemical residues. It does not make a bag warmer, but it is a reasonable tiebreaker between two otherwise similar options.

• Two-way zip beats a single zip for night changes.
• Check the care label before buying; some quilted bags need gentle washing.
• Buy two bags in your main TOG so one can be in the wash.

Decision rules for buying a baby sleeping bag

• Rule 1: Buy for your room, not the season: Measure your nursery temperature for a week before you order. If it stays between 20°C and 24°C, one 2.5 TOG bag covers most of the year. Only buy a second TOG weight if your nights regularly fall outside that band. One well-chosen bag beats three that are almost right.
• Rule 2: When in doubt, go lighter: Overheating is harder to fix at 2 a.m. than being slightly cool. If you are torn between 1.0 and 2.5 TOG, take the 1.0 and add a bodysuit or pajamas underneath. Layers under the bag are easier to adjust than the bag itself.
• Rule 3: Fit the neck before the length: A bag that is too wide at the neck is a safety problem even if the length is correct. Test the neck opening with two fingers and check the armholes before you cut off the tags. If the neck slips over the chin, return it.
• Rule 4: Prioritize a two-way zip and easy washing: Night changes and spit-up happen. A two-way zip and a bag that survives a gentle machine wash will get used far more than a delicate one that stays in the drawer. Practical closures beat decorative details.
• Rule 5: Replace, don't stretch: Move up a size when your baby's height or weight reaches the top of the manufacturer's range, or when the bag starts to pull across the shoulders. Do not keep using a bag your child can unzip or climb out of. Check the fit every few months, not just at purchase.

Cam Cam Copenhagen pieces that support a sleep routine

• Swaddle - GOTS - Berries: A 100% organic, GOTS-certified cotton muslin swaddle in the softest cotton muslin, printed in rose, red, and blue shades on a cream white background. Muslin breathes well, so it works as a light layer in a warm nursery or as a pram cover when a full sleeping bag would be too warm.
• Muslin Cloth, 3-pack - GOTS Mix - Berries: A mixed 3-pack of soft muslin cloths in 100% premium organic, GOTS-certified cotton, wrapped with a grey ribbon. Useful at the changing table and for wiping up night feeds, and the ribbon wrap makes it an easy baby shower gift alongside a sleep bag.
• Short Sleeved Body Olivia - GOTS - Capri: A short-sleeve body with a ruffled collar, made from soft stretchy jersey cotton, available in several prints and in multiple sizes. This is the base layer you put under a low-TOG bag on warm nights; choose the size that fits snugly without pressing on the neck.
• Toiletry bag - OCS - Praline: A quilted toiletry bag coated inside and out for water repellency, with an inside pocket, brass zippers, and a delicate lining. Not a sleep product, but a practical way to keep the nursery shelf or hospital bag organized so the sleep routine stays simple.

Who this approach fits

Best for

• Parents who want one clear TOG rule instead of a drawer full of bags
• Nurseries with a stable overnight temperature between roughly 20°C and 24°C
• Families who prefer layering a bodysuit under a lighter bag over buying multiple weights

Not for

• Homes with no way to measure room temperature, where a wearable blanket with adjustable layers may suit better
• Babies who can already unzip or climb out of a cot, who need a different sleep setup entirely
• Parents looking for a medical recommendation; ask your health visitor or pediatrician for advice specific to your baby

Pick the TOG that matches your nursery's real overnight temperature, check the neck fit before anything else, and keep the base layer simple. Two well-chosen bags in your main weight, washed and rotated, will cover more nights than a shelf of seasonal buys.