It is one of the questions every new parent asks at least once, usually at 11pm with a thermometer in one hand: what should my baby wear to bed tonight? Too many layers and they overheat. Too few and they wake up cold. And the answer changes with the weather, the room and the season.

This guide gives you a simple starting point for every room temperature from below 16°C to above 26°C, explains what TOG means on a baby sleeping bag, and covers the safer sleep basics that matter more than any outfit.

What temperature should a baby's room be?

The Lullaby Trust, the UK's safer sleep charity, advises keeping the room your baby sleeps in at 16–20°C. A cheap room thermometer near the cot is the easiest way to know rather than guess, because a room that feels comfortable to you can be warmer or cooler than you think.

Overheating is linked to a higher risk of sudden infant death syndrome (SIDS), so it is better for a baby to be slightly cool than too warm. Babies don't need to be hot to sleep well.

What to dress your baby in at every room temperature

Use this as a starting point, then check your baby (see below) and adjust. Always follow the TOG guidance printed on your own sleeping bag, because brands vary.

Swipe the table sideways to see every column.

If you use a blanket instead of a sleeping bag, use lightweight cellular blankets, place your baby feet to foot of the cot and tuck the blanket in no higher than their shoulders. Never put a blanket over the top of a sleeping bag.

What to dress a baby in at 20 degrees

20°C is the top of the recommended range, so keep it light. A short-sleeved bodysuit under a 1.0 TOG sleeping bag, or a cotton sleepsuit on its own with a light 1.0 TOG bag, works for most babies. If the room is creeping above 20°C, open a window slightly or draw the curtains in the day rather than adding or removing lots of layers at bedtime.

What to dress a baby in at 18 degrees

18°C sits right in the middle of the ideal range. A sleepsuit inside a 2.5 TOG sleeping bag is the classic combination. If your baby runs cool, add a short-sleeved bodysuit underneath; if they run warm, the sleepsuit alone is usually plenty.

What to dress a baby in at 16 degrees and below

At 16°C, a long-sleeved bodysuit under a sleepsuit and a 2.5 TOG bag will keep most babies cosy. Below 16°C, add a layer of clothing or use a higher TOG bag designed for cold rooms, rather than piling blankets on top.

What does TOG mean?

TOG is a measure of how warm a fabric is: the higher the number, the warmer. Baby sleeping bags are usually sold in a few standard weights:

• 0.5 TOG for very warm rooms and summer nights
• 1.0 TOG for warmer rooms, roughly 20–24°C
• 2.5 TOG for the recommended 16–20°C, and the most-used weight in UK homes for most of the year
• 3.5 TOG for cold rooms below 16°C

TOG only tells you about the bag. What your baby wears underneath matters just as much, which is why the table above pairs the two.

How many layers should a baby wear to sleep?

A useful rule of thumb is that a baby needs one more layer than you would be comfortable in, but a sleeping bag counts as a layer. In practice that usually means one or two layers of clothing plus the sleeping bag. Don't add a hat, and don't use a sleeping bag or sleepwear with a hood indoors, because babies lose heat through their heads and covering them makes overheating more likely.

How to check your baby isn't too hot or too cold

Feel the back of your baby's neck or their chest. If the skin feels hot or sweaty, remove a layer. If it feels cool, add one. Don't go by their hands and feet: these are almost always cooler than the rest of the body and are not a reliable guide.

If your baby has a temperature or seems unwell, dress them in fewer layers, not more, and speak to your GP, health visitor or NHS 111 if you are worried.

Safer sleep basics

• Always put your baby on their back to sleep, in a clear, flat cot or Moses basket.
• Choose a sleeping bag that fits well around the neck and arms, so your baby can't slip down inside it.
• Keep the cot away from radiators, heaters and direct sunlight.
• No hats, hoods, pillows, duvets or bumpers in the cot.
• Take outdoor clothes and hats off as soon as you come inside, even if your baby is asleep.

For the full guidance, see The Lullaby Trust.

Why fabric matters at night

Synthetic fabrics can trap heat and sweat against the skin, which is the opposite of what you want for a baby who is wrapped up for 10 to 12 hours. Breathable natural fibres like cotton let heat and moisture escape, which helps your baby stay at a comfortable temperature through the night.

Everything we make, including our sleepsuits and sleeping bags, is 100% GOTS certified organic cotton: soft from the first wear and made without harsh chemical finishes. Some favourites for bedtime:

• Peacock Sleeping Bag, 2.5 TOG and Cow Sleeping Bag, 2.5 TOG, for the recommended 16–20°C
• Peacock Zip Babygrow: zip-up sleepsuits make night feeds and nappy changes much quicker
• Star & Moon Cow Two Pack Bodysuits, for the layer underneath

Browse the full range: Organic Cotton Sleepsuits & Babygrows · Organic Cotton Vests & Bodies

Not sure which size? Our baby clothes size guide covers sizing by age, weight and height, including why sleepwear should fit now rather than be bought big.

Common questions

Should my baby wear a sleepsuit under a sleeping bag?

Usually, yes. At the recommended 16–20°C, a sleepsuit inside a 2.5 TOG sleeping bag suits most babies. In warmer rooms, swap the sleepsuit for a short-sleeved bodysuit and use a lighter bag.

Can my baby sleep in just a sleepsuit?

Yes, in a warm room (around 22°C or above) a sleepsuit alone can be enough. In cooler rooms, add a sleeping bag or a lightweight, firmly tucked cellular blanket.

Should my baby wear socks or a hat to bed?

No hat indoors. Footed sleepsuits mean socks aren't usually needed; if your sleepsuit is footless and the room is cool, socks are fine.

Is it OK if my baby's hands feel cold at night?

Yes, cool hands are normal. Check the back of the neck or chest instead. If that feels warm and dry, your baby is a comfortable temperature.