What tog sleeping bag for my baby?

Short answer: the NHS lists 2.5 tog for rooms of 16–20°C, 1.0 tog for 20–24°C and 0.5 tog for 24–27°C. The Lullaby Trust advises a room thermometer where your baby sleeps, and Tommee Tippee says to go by the room temperature, not the weather outside.

Checked against NHS, Lullaby Trust and maker guidance on 19 October 2026.

Sleeping bag tog by room temperature

NHS Best Start in Life and Tommee Tippee Grobag tog guides
Room temperature	NHS tog rating	Grobag tog (maker’s own chart)
16°C and below	Not listed	3.5 tog, “cold nights”
16–20°C	2.5 tog: all year, standard rooms	2.5 tog, “cool to warm nights”
20–24°C	1.0 tog: warmer weather and rooms	1.0 tog, “warm nights”
24–27°C	0.5 tog: hot weather	0.2 tog at 24°C and above, “hot nights”
Above 27°C	Not listed	0.2 tog

The NHS figures are for commercial sleeping bags in general. Tommee Tippee's chart is for its own Grobags, which come in 0.2, 1.0, 2.5 and 3.5 tog. Other makers' ranges differ, so the Lullaby Trust's advice is to follow the tog guide that came with your bag.

What does tog mean?

Tog is a warmth rating: the higher the number, the warmer the bag. Tommee Tippee points out it measures warmth, not thickness. Two bags don't add up: the Lullaby Trust says two 1.0 tog bags together do not make 2.0 tog, because air trapped between layers adds extra warmth, so don't double up.

What should my baby wear under a sleeping bag?

The NHS says to adjust your baby's clothing for the room temperature and the tog. The Lullaby Trust's guidance:

Room temperature	Lullaby Trust guidance
Cooler than 16°C	Add an extra layer of clothing or choose a higher tog bag if your baby feels cold. Don’t add blankets on top of a sleeping bag.
16–20°C	A baby grow (sleepsuit) and a sleep bag.
Warmer than 20°C or hot weather	A lightweight layer such as a short-sleeve bodysuit, or even just a nappy.
Really hot weather	A short-sleeve vest or even just a nappy.

Mother&Baby publishes a midwife's chart that puts it in layers. It's one magazine's guide, not official advice:

Room temperature	Mother&Baby midwife chart
Under 16°C	2.5 tog bag + sleepsuit + vest
16–20°C	2.5 tog bag + sleepsuit
20–22°C	1.0 tog bag + sleepsuit
22–24°C	Sleepsuit
24–27°C	Vest, with or without a 0.5 tog bag
Over 27°C	Nappy

Take hats off indoors: the Lullaby Trust says babies release heat through their heads.

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

Feel their chest or the back of their neck. Hands and feet usually feel cooler, which is normal.
Hot or sweaty skin: remove one or more layers.
Chest feels cold: add a layer of clothing or use a higher tog bag.
If your baby is unwell, the Lullaby Trust says dress them for the room as usual rather than wrapping them up more. If you're worried, call your GP or 111.

Choosing a safe sleeping bag

No hood, with arm holes. GOV.UK's product safety advice for buying a baby sleeping bag: make sure it has arm holes and no hood, and that it fits with no slipping.
Snug at the neck and shoulders. The Lullaby Trust says it should be well fitted around the neck and shoulders so your baby can't wriggle down inside. The NHS says it should fit well around the shoulders so your baby's head can't slip down into the bag. Tommee Tippee's test: when fastened, your baby's head should not pass through the neck hole.
Fit by weight, not just age. The Lullaby Trust says most sleeping bags are sized by weight, so check the maker's guide.
Look for BS EN 16781:2018, the British safety standard for baby sleeping bags (Lullaby Trust).
Not weighted. The Lullaby Trust doesn't recommend weighted sleeping bags for babies under one.

Sleeping bag sizes by age (0–3 years)

Grobag sizes from Tommee Tippee’s size guide
Age	What the guidance says
Newborn to 6 months	Use a bag made for this size and check the maker’s weight guide. Tommee Tippee’s Grobag sleepbags start at 6 months.
6–18 months	Grobag size 6–18 months: from 8.2 kg, 68–86 cm.
From 12 months	The Lullaby Trust says don’t use pillows and duvets for babies under 12 months. For when and which duvet after that, see the toddler duvet tog guide and its sources.
18–36 months	Grobag size 18–36 months: from 11.3 kg, 86–98 cm. Grobag’s Steppee (with feet) comes in 0.2, 1.0 and 2.5 tog, not 3.5.

Tommee Tippee says to stop using a Grobag once your child can climb out of their cot, and never to use one with a cot duvet or blanket. When it's time to move on: what tog duvet for a toddler. For toddlers in pyjamas and a bed, see what should a toddler wear to bed.

Questions

What tog sleeping bag at 18 degrees?

The NHS lists 2.5 tog for standard room temperatures of 16–20°C. The Lullaby Trust suggests a baby grow underneath.

What tog sleeping bag at 22 degrees?

The NHS lists 1.0 tog for warmer rooms of 20–24°C. Tommee Tippee’s Grobag guide also gives 1.0 tog.

Is a 0.5 tog sleeping bag for summer?

Yes. The NHS lists 0.5 tog for hot weather and rooms of 24–27°C.

When should a baby use a 3.5 tog sleeping bag?

Tommee Tippee suggests its 3.5 tog Grobag for rooms of 16°C and below. The NHS list stops at 2.5 tog, and the Lullaby Trust says add a layer or choose a higher tog if your baby feels cold.

Can I put a blanket over a sleeping bag?

No. The NHS says there should be no other bedding, and the Lullaby Trust says don’t add blankets on top of a sleeping bag.

Are hooded baby sleeping bags safe?

GOV.UK’s product safety advice warns that not all baby sleeping bags are safe: choose one with arm holes and no hood, and check it fits with no slipping.

Where these numbers come from

Checked 19 October 2026. Brands change their charts, so always check the size guide of the shop you're buying from.