How to dress a baby for sleep: what the tog on the label actually means

It is 9pm, the room feels cool, and you have two charts open with different answers.

Use the chart that came with your own sleeping bag, not a chart off the internet. Neither The Lullaby Trust nor the NHS page on dressing a newborn publishes a room-temperature-to-tog chart. That absence is the useful answer, because only the maker's guide describes the bag in your hands. Read the room, follow that guide, then check your baby.

This guide is for babies under one at home, for an ordinary night. It does not cover choosing a sleeping bag, swaddling, or managing a heatwave.

Start with the room, not the baby

Both The Lullaby Trust and the NHS page on dressing a newborn give the same practical guide: 16–20 °C for the room where your baby sleeps.

That number is a guide, not a target set for your baby. The Lullaby Trust's own evidence review puts it plainly: the optimum temperature for an individual infant varies widely enough for no specific value to be recommended for all infants. In practice, the test is the baby, not the thermometer — warm to the touch but not sweating.

So the first step is knowing what the room is actually doing. Use a room thermometer where your baby sleeps. A guessed room temperature makes every step after it guesswork.

Tog, when you meet it on a label, is a measure of insulation used for items like baby sleeping bags and blankets. The higher the tog number, the warmer the product.

Why The Lullaby Trust will not give you a tog chart

The Lullaby Trust states outright that it cannot give a chart matching room temperature to clothing layers and tog, and it gives three reasons. Every product uses different materials, so thermal insulation differs. Heat trapped between layers changes the warmth significantly. And every baby is different.

The NHS page on dressing a newborn does the same thing in fewer words. It publishes no tog chart at all. For winter tog thickness, it tells you to check the manufacturer's recommendation.

This matters because the charts you can find do not agree with each other. We checked four UK guides that ranked on page one for this question in September 2026, each publishing a tog chart of its own. 20 °C is the top of that recommended range, and in these four guides it points to 1.0, 1.5 or 2.5 tog, depending on which page you open. On three of the four, it falls into more than one of that page's own bands at once. A gap that wide is not a rounding error. It is what happens when a general chart has to describe products it has never measured.

Follow the tog guide supplied with the specific bag you own. Most bags are sized by weight rather than age, so the maker's card is the place to check both size and warmth.

What to put them in tonight

Work in this order.

1. Read the room. Take the thermometer reading from where your baby will sleep, not the hallway or living room. Keep the cot or Moses basket away from radiators, heaters and direct sunlight.

2. Find your bag's own guide. Look at the card, label or booklet that came with that exact bag and find tonight's temperature on it. That guide was written for the filling, fabric and thickness you are actually using. A general chart is written for none of them.

3. Set the layer underneath. Use the base layer that same guide suggests. For a winter night, the NHS page on dressing a newborn puts a sleepsuit under the sleeping bag.

4. If they feel cold, add clothing, not blankets. If your baby's chest feels cold, add an extra layer of clothing, or move to a higher tog bag next sleep. Do not lay extra blankets over a sleeping bag.

5. If the room sits below the range, add a layer first. The Lullaby Trust says an extra layer will usually help when you cannot bring a cool room up to the guide range. It is rarely necessary to leave the heating on all night; if you do, the Trust says keep it low and certainly no higher than 20 °C.

Three ways layers go wrong

Putting a baby in two sleeping bags does not add the tog numbers together. Two 1.0 tog bags do not make a 2.0 tog bag, and The Lullaby Trust warns this can be dangerous, because air becomes trapped between the layers and increases the warmth. Use one bag, in the tog its own guide gives for the room.

Folding a blanket over does add up. Both the Trust and the NHS say the same thing: a blanket folded in half counts as two blankets. If your baby sleeps under a blanket rather than in a bag, use a single lightweight cellular one and count what you actually laid down.

Hats come off indoors. Babies lose heat through their heads, so a covered head can lead to overheating. Duvets and quilts stay out of the sleep space too.

How to tell you got it right

The Lullaby Trust gives the check point: feel your baby's chest or the back of their neck. Hands and feet will usually be cooler than the rest, and that is normal.

The NHS page words the check a little differently for newborns. If your baby is sweating or their tummy feels hot to the touch, take off some of their clothing or bedding.

From there it is two branches. Hot or sweaty skin means one layer off, then another check shortly after. A cold chest means one layer of clothing on, not a blanket over the bag.

Both authorities point the same way: babies are safer cooler than too hot. The Lullaby Trust's evidence review adds that winter is when it is easiest to overshoot, because parents heat the room and add warm layers at the same time.

Tonight, go and read the label on the bag you already own, and keep its card where you can find it at bedtime. That card, a thermometer and a quick check of the chest are the whole method.

Keep reading: for more on the 16–20 °C guide and what to do when the room will not stay in it, see what temperature should a baby’s room be? For the checks you make later in the night, our guide to dream feeds and night checks covers doing them without waking everyone. If you are shopping for a new parent, our baby shower gift ideas that actually get used may help.

References

1. The Lullaby Trust, How to dress your baby for sleep — room-temperature guidance, the refusal to publish a general tog chart with its three reasons, the manufacturer's guide, layering traps and the chest-or-back-of-neck check.
2. NHS Best Start in Life, How to dress a newborn baby — newborn scope, 16–20 °C range, manufacturer deferral for tog thickness, folded-blanket rule and the sweating-or-hot-tummy wording.
3. The Lullaby Trust, Temperature and room temperature — the research (PDF) — evidence review behind the guidance, including why no single ideal temperature can be recommended for all infants.
4. The Lullaby Trust, Your baby's room temperature — heating guidance and adding a layer when the room sits below the range.