By Gemma, Child Sleep Specialist
Choosing the right sleeping bag TOG shouldn’t feel like decoding science homework! However, we need to bear in mind different room temperatures, changing seasons and hundreds of sleeping bags on the market and therefore it can get confusing fast!
This sleep bag tog guide will show you exactly how to choose the right tog rating for your little one, including a simple sleeping bag TOG guide chart, safety advice, when to choose 2.5 tog and 3.5 tog bags, and what your baby should wear underneath each option.
Whether your baby sleeps in a cot or Moses basket, this guide will help you sleep safely, avoid the risk of overheating and keep your little one comfortable year round.
Table of Contents
Disclosure: This post may contain affiliate links. I receive a commission if you buy something on my recommendation. Purchasing via an affiliate link doesn’t cost you any extra, and I only recommend products and services I trust.
What Is a Sleeping Bag TOG?
TOG stands for Thermal Overall Grade, which simply tells you how warm a sleeping bag is. The tog rating tells you how much heat the bag holds:
Lower tog = holds less heat so is cooler
Higher tog = holds more heat so is warmer
Baby sleeping bags or sleep sacks need very specific tog ratings because your baby’s temperature regulation is still developing. Unlike adults, babies can’t remove covers, kick off heavy duvets or adjust their body temperature as easily.
This is why choosing the appropriate tog rated sleeping bag is essential for safe sleep.
How Sleeping Bag TOG Ratings Are Tested
TOG ratings aren’t guessed. Every baby sleeping bag is tested in a specialist laboratory using strict European safety standards. The finished bag is placed on a heated plate that mimics warm skin, and the lab measures how much heat escapes through the fabric. The result gives the thermal overall grade – the TOG rating. This process ensures that each sleeping bag is tested in a controlled environment, so parents can trust that a 1.0 tog, 2.5 tog or 3.5 tog will provide the level of warmth it claims, without risking overheating.
Baby Sleeping Bag TOG Guide Chart (Quick Reference)
Use this sleep bag tog guide chart to choose the right tog based on room temperature, not the weather outside or what you sleep under.
NOTE: This is a guide. Follow the manufacturers recommendations for each individual sleeping bag,
| Room Temperature | Recommended TOG | What Baby Should Wear Underneath |
|---|---|---|
| >24°C (warm room temperatures) | 0.5 tog | Short-sleeve bodysuit or vest |
| 21–23°C | 1.0-1.5 tog | Bodysuit or light sleepsuit |
| 16–20°C | 2.5 tog | Sleepsuit (+ vest if closer to 16°C) |
| <16°C (very cold nights) | 3.5 tog | Long sleeve sleepsuit (+ vest if really cold) |
Always check your baby’s chest or back to assess warmth. Hands and feet will often feel cool and don’t reflect core temperature.
Why Baby Sleeping Bags Are Different to Adult Duvets
One of the biggest misconceptions I hear is:
“I sleep under a 10 tog duvet… won’t my baby be freezing in a 2.5 tog?”
No. …and here’s why.
Babies:
- have developing temperature control
- can’t push blankets away
- get warm quickly
- sleep in a controlled sleep space (cot/Moses basket)
- wear layers under the sleeping bag
Adults:
- can throw blankets off
- regulate heat better
- generate more body heat
- use duvets that trap far more warm air
Baby sleeping bags are deliberately regulated to prevent babies overheating, reduce the risk of SIDS, and keep your little one safe.
This is why you’ll never see a baby 7–10 tog sleeping bag. It simply wouldn’t be safe. Whilst we’re here, make sure you’re up to date on Safe Sleep guidance from trusted sources such as the NHS and The Lullaby Trust.
See this blog post for more information on whether newborns should use sleeping bags.
Understanding Different TOG Ratings for Baby Sleeping Bags
0.5 Tog
Perfect for:
- hot weather
- warmer nights or tropical holidays with no air-con
- room temperatures around 24°C+
Keeps your baby cool while preventing them wriggling underneath loose blankets.
1.0 Tog
A great year-round option for different room temperatures (21–23°C).
Best for mild nights and consistent controlled house temperatures (controlled by air-con or thermostatic valves).
Ideal when you can maintain a current warm temperature in the sleep space.
2.5 Tog
This is the most popular winter warmth option.
Use it when your baby’s room is between 16–20°C.
Most parents reach for a 2.5 tog when the nights start to get chilly and you see the room temperature lowering overnight.
3.5 Tog
A heavier winter bag for very cold nights or older houses that significantly drop in temperature overnight. Also for houses that can’t afford to heat the house all day.
Use when the room is under 16°C, and check your baby’s temperature regularly.
Important: Your baby should never feel sweaty, hot or clammy. That means the tog is too warm (even if it’s really chilly in the house!).
If you’re needing a top winter sleeping bag for temperatures under 16°C, check this one out from Love to Dream.
Sleeping Bags With Arms, No Arms, and Sleep Bags With Feet
Arms or no arms?
Baby sleeping bags come with:
- no arms (most newborn bags)
- detachable sleeves
- padded sleeves
Sleeves do not increase the tog.
They simply add upper-body comfort for colder nights.
Sleeping bags with feet
Brands like ErgoBaby offer on-the-move sleeping bags with little foot holes. These are brilliant for:
- wriggly toddlers
- those with sensory preferences (some don’t like fabric on their feet)
- bedtime routines where they’re toddling about
- giving little one more independence
Whether they wear socks is down to preference.
How to Choose the Right Size Sleeping Bag
Choosing the correct size sleeping bag is crucial for safety.
A safe sleeping bag:
✔ fits snugly at the neck hole
✔ sits securely around the baby’s shoulders
✔ prevents wriggling underneath additional covers
✔ supports healthy hip development
You should not size up early. Choose the size based on your baby weighs, not their age (especially when they are under 6 months of age or premature).
Safe Sleep: What Should Be in the Cot or Moses Basket?
For the first year, your baby’s sleep space needs to be completely clear.
This means no:
- loose blankets
- additional covers
- pillows
- cot bumpers
- toys
- comforters
A sleeping bag helps keep your baby safe by maintaining a constant temperature without loose bedding.
Baby Sleeping Bag TOG Guide FAQ
What tog sleeping bag should my baby use?
Choose the tog based on the room temperature, not the season or what you sleep under yourself. Use the sleeping bag TOG guide in tis blog as your starting point, then adjust layers underneath depending on whether your little one runs warmer or cooler. Always check your baby’s chest or back to make sure they’re comfortably warm.
Is a 2.5 tog sleeping bag warm enough for winter?
Usually, yes. Most UK bedrooms sit between 16–20°C overnight in winter, and a 2.5 tog is specifically designed for this range. It provides enough insulation to keep your baby comfortable while still preventing overheating. If your home is older, draughty or tends to drop below 16°C, you may occasionally need a 3.5 tog, but this is less common.
When should I use a 3.5 tog sleeping bag?
A 3.5 tog sleeping bag is for very cold rooms. Typically <16°C or for houses that cool significantly overnight. It’s more insulation than most babies need, so only use a 3.5 tog when the room temperature genuinely warrants it, and always check your baby’s chest to avoid the risk of overheating.
What should my baby wear under a sleeping bag?
This depends on the room temperature and the sleeping bag tog.
For warmer rooms (21°C+), a cotton bodysuit is enough.
As temperatures drop (17–20°C), you’ll likely need a vest + sleepsuit.
On colder nights (<16°C), add an extra layer like a vest with your sleepsuit.
Clothing works with the TOG to maintain a safe, constant temperature. Check your sleeping bag manufacturers recommendations.
Are baby sleeping bags safe?
Yes, when they fit correctly, are the appropriate TOG for the room, and are used without loose blankets or additional covers. Sleeping bags help prevent babies from wriggling underneath blankets and reduce the risk of SIDS by keeping the sleep space clear. Make sure the neck hole and shoulders fit snugly to avoid slipping down inside the bag.
Can babies overheat in sleeping bags?
Yes, if the wrong TOG or too many layers are used. Overheating is one of the biggest safety risks, so always dress baby according to the room temperature and check their chest regularly. If your little one feels sweaty, hot, or flushed, remove a layer or choose a lower TOG immediately.
Can my baby sleep in a sleeping bag year round?
Absolutely. Sleeping bags are designed to be used all year round, as long as you switch between 0.5, 1.0, 2.5 or 3.5 tog depending on the weather and your baby’s sleep environment. This helps maintain a safe and consistent sleeping temperature every night.
Should I choose a sleeping bag with arms or without?
Sleeves add comfort, not warmth, the tog stays the same. Bags with detachable sleeves are great for colder nights or toddlers who prefer covered arms. For younger babies, sleeveless bags are safer because they help prevent overheating and support healthy temperature regulation.
What about sleeping bags with feet?
These are great for toddlers on the move. Foot openings give them independence during bedtime routines and early mornings. They can choose socks or no socks based on comfort.
How do I choose the right size sleeping bag?
Choose the size based on your baby’s weight, not just their age, especially when they are a newborn or premature. The neck hole and shoulders should be snug so your baby can’t slip down inside the bag. Never size up early, an oversized bag can ride up and interfere with breathing or temperature control.
Can my baby sleep with a comforter or blanket?
For the first year, the cot or Moses basket should be completely clear, NO blankets, pillows, cot bumpers or soft toys. From around 12 months, you can introduce a small comforter if you wish, but never use additional blankets with a sleeping bag.
Final Thoughts: Choosing the Right TOG Doesn’t Need to Be Hard
Choosing the right tog rating is one of the simplest ways to keep your little one comfortable and sleep safely.
Use the sleeping bag tog guide, check your baby’s chest, and adjust layers based on different room temperatures, that’s it.
If you’re still unsure about baby sleep, room temperature, bedtime routine or night-time wake-ups, I’m here to help.
Read More:
Time to move from a sleeping bag to toddler duvet?
Moving your baby to their own room at 6 months,
My 4 Month Sleep Regression Guide
Get in touch!
For more support, tips, and tailored advice for your child’s unique sleep needs please get in touch! My sleep consultations and courses can help guide you through every step of your child’s sleep journey. And if you’re struggling with any challenges along the way, including separation anxiety at night on return, don’t hesitate to reach out.
Disclaimer
This Sleeping Bag TOG Guide is intended for general information only and is not medical advice. Always follow Safe Sleep guidance from trusted sources such as the NHS and The Lullaby Trust, and refer to the manufacturer’s specific recommendations for any sleeping bag you use. Every baby is different, and this guide should be used alongside professional advice where needed.
