What should you dress your baby in for sleep? Put your baby in a well-fitting baby sleeping bag over a short-sleeve vest, adding a sleepsuit if the room needs it, and pick the tog using your bag's own printed guide. Babbez explains the clothing, tog and sizing; for room temperature, overheating and every safe-sleep judgement, follow The Lullaby Trust and the NHS, who also say never to add loose blankets on top of a sleeping bag.
Key takeaways
- Tog is a warmth rating, not a thickness — the higher the tog, the warmer the sleeping bag. UK bags are usually sold in 0.5, 1.0, 2.5 and 3.5 tog (some brands add 1.5 tog).
- Sleeping bags are sized by weight and length, not age alone, and must fit snugly at the neck and shoulders. Look for the UK safety standard BS EN 16781:2018.
- The Lullaby Trust and the NHS own the safe-sleep rules here: room temperature 16–20°C, back to sleep, a firm flat clear cot, and checking your baby is not too hot. Babbez does not set these.
- The Lullaby Trust and the NHS say to check for overheating at the chest or back of the neck — cool hands and feet are normal.
- There is no single Babbez "at X°C use Y tog" rule. Follow the tog guide printed on your own bag by its manufacturer, and follow The Lullaby Trust for room temperature.
Babbez sells baby and children's clothing, so we can explain how vests, sleepsuits and sleeping bags are made, sized and used. This guide covers clothing and product facts only. It is written by the Babbez team, who are not doctors or health visitors, and it is not medical or safe-sleep advice. For safe sleep, overheating and room temperature, always follow The Lullaby Trust and the NHS, linked throughout, and read our medical disclaimer.
What does tog mean on a baby sleeping bag?
The Lullaby Trust describes it plainly: "Tog is a measure of insulation (warmth) that is used for items like baby sleeping bags and blankets." A higher tog is warmer, and tog rates warmth rather than fabric thickness — a lightweight bag can still be a high tog. The table below explains the common UK togs as a product fact.
| Tog rating | Relative warmth | Typically sold for |
|---|---|---|
| 0.5 tog | Lightest | Warm summer nights and hot rooms |
| 1.0 tog | Light | Warmer rooms and milder nights |
| 1.5 tog | Medium (not all brands) | Spring and autumn transitional nights |
| 2.5 tog | Warm (a common all-year choice) | Cooler rooms and most of the year |
| 3.5 tog | Warmest | Cold winter rooms, where a brand offers it |
What should you dress a baby in to sleep?
For the clothing layers, a simple, well-tested combination is a short-sleeve vest (the bodysuit base layer), a sleepsuit or babygrow over it, and a baby sleeping bag sized and togged for the room. A sleeping bag is used instead of loose blankets, duvets or quilts, so your baby cannot wriggle down under covers or cover their head. The NHS lists baby sleeping bags among the safer alternatives to loose bedding. In a warm room a vest alone under the bag is often enough.
How warm those layers make your baby is a safety judgement, not ours to set. The NHS advises that "overheating can increase the risk of SIDS. Babies can overheat because of too much bedding or clothing, or because the room is too hot," and The Lullaby Trust adds that "the risk of sudden infant death syndrome (SIDS) is higher in babies who get too hot." Use the chest and back-of-neck check below whenever you add or remove a layer.
What is the right room temperature for a baby's room?
The Lullaby Trust states, "The recommended room temperature for babies is 16-20°C," and the NHS advises to "keep the room at a temperature between about 16 to 20C." Because it is hard to judge by feel, The Lullaby Trust suggests you "use a room thermometer in the rooms where your baby sleeps."
How can you tell if your baby is too hot or too cold?
The Lullaby Trust and the NHS give one clear method, which we relay here: feel your baby's chest or the back of their neck. As the NHS puts it, "Check your baby's temperature by feeling their chest or the back of their neck. Do not worry if their hands or feet feel cool, this is normal." The Lullaby Trust likewise says to "feel your baby's chest or the back of their neck (your baby's hands and feet will usually be cooler, which is normal)." If the chest or neck feels hot or sweaty, remove a layer. None of this is Babbez's rule — follow The Lullaby Trust and the NHS, and see our medical disclaimer.
What tog sleeping bag should you use for the room temperature?
The Lullaby Trust advises: "Follow the manufacturer's tog guide to ensure you're using the right tog sleep bag for the room temperature." There is no single canonical "at this temperature, use this tog" table, because different products insulate differently, so the guide printed on your own bag is the one to follow. The answer has two parts, and neither is a Babbez rule: for which tog at which temperature, follow the guide printed on your own bag by its maker; for the room temperature itself and whether your baby is too hot, follow The Lullaby Trust and the NHS above.
The table below is an example only of one manufacturer-style guide (a Tommee Tippee / Grobag-range guide, summarised by UK retailer Tiny Sleepers). It is here to show what such a guide looks like — not as our rule, and not as The Lullaby Trust's. Figures vary from brand to brand, so read the tog-and-temperature label on your own sleeping bag and follow that, alongside The Lullaby Trust and NHS for the room-temperature basics.
| Room temperature | Example tog this maker suggests |
|---|---|
| Below about 14–16°C | 3.5 tog |
| About 16–20°C | 2.5 tog |
| About 20–24°C | 1.0–1.5 tog |
| About 24–27°C | 0.5 tog |
The Lullaby Trust says, "If you're using a baby sleeping bag, don't add extra blankets on top. Add an extra layer of clothing or choose a higher tog sleeping bag." And do not double up bags: The Lullaby Trust warns that "dressing your baby in two 1.0 tog sleep bags does not make the sleep bag 2.0 tog," because air trapped between the layers increases the warmth unpredictably.
What size baby sleeping bag does your baby need?
Sizing is a product-fit fact we can explain. As The Lullaby Trust notes, "most baby sleeping bags... are fitted by weight, not age, so always check the manufacturer's guidelines." The fit at the neck and shoulders matters most, so your baby cannot wriggle down inside or slip their head through the neck hole. The bands below are typical UK figures; confirm against your own bag.
| Age band | Approx. minimum weight to start | Fit notes |
|---|---|---|
| 0–6 months (newborn) | From about 3.5–4 kg (around 8lb 13oz) | Must fit snugly at neck and shoulders so the head cannot slip through the neck hole |
| 6–18 months | From about 8 kg (around 18lb) | Maximum length around 86 cm |
| 18–36 months | From about 11.5 kg (around 24lb) | Maximum length around 98 cm |
When you buy, look for a bag made to BS EN 16781:2018. The Lullaby Trust names this as the safety standard for baby sleeping bags: "The safety standard for baby sleeping bags (sleepbags) is: BS EN 16781:2018."
What do The Lullaby Trust and the NHS say about safe sleep?
Everything in this section is safe-sleep guidance from the authorities, relayed word-for-word where possible — not Babbez's opinion. Follow the full guidance from The Lullaby Trust and the NHS:
- Back to sleep. The NHS advises to "always place your baby on their back to sleep in the feet-to-foot position – this means with their feet at the bottom of the cot, Moses basket or pram."
- Firm, flat, clear cot. The NHS says to "use a firm, flat mattress" and "keep your baby's cot clear of anything that could cover their face and head – do not use pillows, duvets, cot bumpers, loose blankets, soft toys."
- No hats indoors for sleep. The NHS advises to "remove hats and extra clothing as soon as you come indoors... even if it means waking your baby," because a covered head indoors can cause overheating.
- A sleeping bag rather than swaddling. The NHS lists, among its advice, to "not swaddle your baby (baby sleeping bags are safer)."
- No weighted products. The Lullaby Trust states, "Weighted swaddles, blankets and sleeping bags are not recommended for babies under one year as there is a risk of overheating and head covering."
What should a baby wear to sleep in hot weather?
In warm weather, dress your baby in fewer, lighter layers. The Lullaby Trust says, "In really hot weather, it's fine to have your baby in a short sleeve vest or even just a nappy." It adds that if you feel the chest or the back of the neck and "they feel clammy or sweaty, these are signs they're getting too hot, so remove a layer of clothes and adjust the room temperature if possible." Keep following all the other safer-sleep guidance above, even when it is hot.
Frequently asked questions
What does tog mean?
Tog is a warmth (thermal-insulation) rating for baby sleeping bags and bedding. The Lullaby Trust calls it "a measure of insulation (warmth)." The higher the tog, the warmer the bag; it measures warmth, not fabric thickness.
What tog sleeping bag should I use at what temperature?
There is no single universal chart, because warmth varies by product. The Lullaby Trust advises following "the manufacturer's tog guide" to match your bag to the room, and keeping the room at 16–20°C. Read the label on your own bag, and follow The Lullaby Trust and the NHS for room temperature and for checking your baby is not too hot.
Are baby sleeping bags sized by age or by weight?
By weight and length, not age alone. The Lullaby Trust says most bags "are fitted by weight, not age, so always check the manufacturer's guidelines." The neck and shoulders must fit snugly so your baby cannot slip down inside the bag.
Can I put a blanket over my baby's sleeping bag if it is cold?
No. The Lullaby Trust advises: "If you're using a baby sleeping bag, don't add extra blankets on top. Add an extra layer of clothing or choose a higher tog sleeping bag." Never use two sleeping bags at once. This is a safe-sleep judgement from The Lullaby Trust, not from Babbez.
Does my baby need a hat to sleep indoors?
No. The NHS advises removing hats and extra clothing as soon as you come indoors, and The Lullaby Trust explains that a covered head indoors can cause a baby to overheat. Hats are for outdoors, not for sleep at home.
Sources (safe-sleep, room-temperature and overheating guidance belongs to these authorities, not to Babbez):
- The Lullaby Trust — How to dress your baby for sleep (tog definition, BS EN 16781:2018, weight-not-age sizing, blankets, two-bag warning, manufacturer's tog guide, weighted products): lullabytrust.org.uk
- The Lullaby Trust — Baby room temperature (16–20°C, overheating, room thermometer, chest/back-of-neck check): lullabytrust.org.uk
- The Lullaby Trust — Hot weather (short-sleeve vest or just a nappy): lullabytrust.org.uk
- NHS — Reduce the risk of sudden infant death syndrome (back to sleep, firm flat mattress, clear cot, no swaddling, temperature check, hats indoors): nhs.uk
- Tommee Tippee — What should a baby wear to bed (UK garment vocabulary): tommeetippee.com
- Example manufacturer-style tog-and-temperature guide (UK retailer; figures differ by brand, use your own bag's label): tinysleepers.co.uk
