How to Choose the Right Sleep Bag for Your Baby

Getting baby sleep right is a top priority for any parent. A baby sleeping bag (or sleep bag) is one of the best ways to keep your little one snug, safe, and comfortable throughout the night. But with so many options available, how do you choose the right one?

Let’s break it all down—TOG ratings, materials, sizes, and everything else—so you can find the best baby sleeping bag for a safe and restful baby sleep.

 

Why Use a Baby Sleeping Bag Instead of Blankets?

A sleeping bag for your baby is not just about keeping them cosy—it’s actually a safer option than blankets. Babies can easily kick off their bedding, or worse, pull a loose blanket over their face, increasing the risk of overheating or restricted breathing [1].

✅ A sleep bag keeps your baby warm without overheating
✅ Prevents the risk of loose blankets covering their face
✅ Encourages back sleeping—the safest sleep position [2]
✅ Provides a familiar sleep environment for better sleep routines

So, how do you choose the best baby sleeping bag? Let’s start with TOG ratings.

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What is a TOG Rating & How to Choose the Right One?

TOG stands for Thermal Overall Grade

This indicates how warm a sleeping bag will keep your baby. The higher the TOG, the warmer the bag. However, TOG ratings are only relevant for regular fibre sleeping bags made from materials like cotton and polyester.

Merino wool does not require a TOG rating because it naturally regulates temperature, reducing the risk of overheating. While TOG ratings can still serve as a general warmth guide, wool sleeping bags are safer as they wick away moisture and adapt to your baby's body temperature, even if you layer clothing underneath.

Why Merino Wool is Best for Temperature Control
Unlike cotton, merino wool keeps babies warm without overheating. It helps regulate body temperature by trapping heat when it's cold and releasing excess heat when it's warm—making it the ideal choice for year-round comfort.

How to Choose the Right TOG rating?

A sleep bag comes with a TOG rating, which tells you how warm it will keep your baby. The higher the TOG, the warmer the bag. The right TOG depends on the temperature of the room where your baby sleeps.

Tip: The ideal room temperature for baby sleep is between 16-20°C [3]. Always check your baby’s neck to make sure they are not too hot or too cold—if they’re sweaty, they may be overheating!

 

What Should My Baby Wear Under a Sleep Bag?

The clothing your baby wears inside the sleeping bag depends on TOG rating and room temperature. Here’s a quick guide:

 

Make sure your baby’s clothing is breathable to avoid overheating. Swaddles should only be used when your baby is very young, and once they start rolling, it’s time to switch to a baby sleep sack [4].

 

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How to Choose the Right Size Baby Sleeping Bag?

The right sleeping bag should be snug around the chest but loose around the legs to allow for movement.

🔹 Too small? It will feel restrictive.
🔹 Too big? Your baby could slide down inside, making it unsafe.

Use this simple formula to find the right size:

📏 Baby’s length – head size + 10cm = Ideal sleep bag size

Tip: Make sure the neck opening is not too wide—your baby’s head should not slip through when fastened.

 

Key Features to Look for in a Baby Sleeping Bag

✅ Double-ended zip – Makes night-time nappy changes easier
🌿 Breathable materials – Merino wool is superior to cotton for temperature control
🛏 No thick seams or buttons – Ensures a comfortable sleeping position
🦶 Sleeping bags with legs – Great for older babies who like to move

A good sleeping bag should feel snug but not tight, providing warmth without restricting movement.

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Safe Sleep: Things to Avoid

🚫 No loose blankets or cot bumpers – They can pose a suffocation hazard.
🚫 No hats or extra layers – Babies cannot regulate temperature like adults.
🚫 Avoid synthetic fabrics – Opt for natural, breathable materials like merino wool instead of cotton.
🚫 Don’t let your baby overheat – Monitor room temperature and adjust layers accordingly.

Layering in Merino Wool is the most effective way to prevent overheating while keeping your baby warm and comfortable.

Following these safe sleeping tips will help your baby sleep better and reduce the risk of overheating.

TOG Ratings & Room Temperature Guide

Tip: The ideal room temperature for baby sleep is 16-20°C. Always check your baby's neck to ensure they are not too hot or too cold—if they’re sweaty, they may be overheating.

Choose Merino Wool Over Cotton – Merino wool is more breathable, wicks away moisture, and reduces overheating risk, even when layered.

Ready to Find the Best Baby Sleeping Bag?

Now you know how to choose the right baby sleeping bag—but where do you find the perfect one?

✅ Soft, breathable fabrics to keep your baby comfortable
✅ Double-ended zips for easy nighttime changes
✅ Perfect TOG ratings for every season

Give your little one the best sleep ever with our cosy, safe, and TOG-rated baby sleep sacks!

👉 Shop the collection now: Baby Sleeping Bags

 

Baby Sleeping Bags FAQs

What is a baby sleeping bag and why should I use one?

A baby sleeping bag is a wearable blanket designed to keep your baby warm and comfortable during sleep. It's a safer alternative to loose bedding, reducing the risk of overheating and promoting better sleep. Baby sleeping bags are designed to maintain a consistent temperature throughout the night, ensuring your little one stays cosy without the need for additional blankets.

How do I choose the right tog for my baby's sleeping bag?

To choose the right tog for your baby's sleeping bag, consider the temperature of your baby's room. Lower tog ratings (0.5-1.0) are suitable for warmer temperatures, while higher togs (2.5-3.5) are best for colder environments. Always check the clothing guide provided by sleeping bag companies to ensure you select the appropriate tog for your baby's comfort and safety.

How should I dress my baby for sleep when using a sleeping bag?

When using a sleeping bag, dress your baby in lightweight, breathable sleepwear. For cooler temperatures, you can layer with a onesie or light weight baby pyjamas underneath. In warmer weather, a diaper and thin bodysuit or sleepsuit may suffice. Always check your baby's temperature by feeling their chest or back to ensure they're not too hot or cold.

At what age can my baby start using a sleeping bag?

Most babies can start using a sleeping bag from birth, provided it's the right size and weight for their age. However, some parents prefer to swaddle newborns for the first few weeks before transitioning to a sleeping bag. Always follow the manufacturer's age and weight recommendations when choosing a sleeping bag for your little one.

How Can I Prevent My Baby from Overheating in a Sleeping Bag?

To prevent overheating:
✔ Choose a merino wool sleeping bag instead of synthetic or cotton alternatives.
✔ Dress your baby in light, breathable layers underneath.
✔ Regularly check their chest or back—if they feel warm or sweaty, remove a layer.
✔ Ensure good air circulation in the room.
✔ Select sleepwear with foot closures (such as turnover cuffs) to prevent cold feet and avoid socks slipping off during the night.

What features should I look for in a safe sleeping bag?

A safe sleeping bag should have a fitted neck and armholes to prevent your baby from slipping inside. Look for bags with secure fastenings, such as zippers or snaps, that your baby can't easily undo. Choose bags made from breathable, natural fabrics like cotton or merino wool. Ensure the sleeping bag is the right size for your baby's height and weight to avoid any loose fabric around the face.

How do I compare sleeping bags to find the best one for my baby?

When comparing sleeping bags, consider factors such as tog rating, size, material, and ease of use. Look for reputable brands such as Hello Night Kids that meet safety standards. Read reviews from other parents and consider your baby's specific needs, such as temperature regulation or ease of diaper changes.

Can I Use Sleep Suits Instead of Traditional Sleeping Bags?

Yes! Sleep suits are a great alternative to traditional sleeping bags. They offer the same temperature-regulating benefits while providing more mobility for active babies. Many sleep suits come with built-in feet or legs, which make it easier for your baby to move and for you to do quick nappy changes.

Choose a merino wool sleep suit for better temperature control and moisture-wicking properties.

How often should I wash my baby’s sleeping bag?

Unlike cotton, merino wool is naturally antimicrobial and odour-resistant, meaning it doesn’t need to be washed frequently. Instead, we recommend airing it out between washes.

Washing tip: Wash your baby’s merino wool sleeping bag only when necessary, typically every 1-2 weeks, unless soiled. This helps maintain the wool’s natural benefits and longevity.

How can I transition my baby from swaddling to using a sleeping bag?

To transition from swaddling to a sleeping bag, start by swaddling with one arm out for a few nights. Then, try both arms out of the swaddle. Once your baby is comfortable with this, introduce a lightweight sleeping bag. You can use transitional products like the Hello Night Kids swaddle, which allows for a gradual transition. Be patient and consistent, as it may take some time for your baby to adjust to the new sleeping arrangement.

References:

[1] Red Nose Australia – Safe Sleep Guidelines: https://rednose.org.au/section/safe-sleeping
[2] NHS – Back to Sleep Advice: https://www.nhs.uk/conditions/sudden-infant-death-syndrome-sids/
[3] Lullaby Trust – Room Temperature Guide: https://www.lullabytrust.org.uk/
[4] Safe Sleep Advice – Swaddle vs. Sleep Bag: https://www.lullabytrust.org.uk/safer-sleep-advice/
[5] Baby Centre – Overheating in Babies: https://www.babycentre.co.uk/a1050025/keeping-your-baby-at-the-right-temperature