What is a baby sleep bag or sack?

A baby sleep bag, also called a wearable blanket or sleep sack, is a bag-like garment or covering worn by infants for sleeping. It replacing loose blankets in the crib that can cover your baby's face and interfere with breathing.  

Since 2005, The American Academy of Pediatrics has recommended the use of wearable blankets for safe sleep. Unlike regular blankets, a wearable blanket or sleep sack is worn over your child's sleepwear, so it won't be kicked off and baby stays covered all night. The sleep bag will become part of your child's bedtime routine, providing a sense of security and comfort.

What is the TOG rating of your sleep bags? Are they winter or summer weight?


Our 4 Season baby sleeping bags are designed to be worn year round. Therefore, they do not have a fixed TOG. They are made from 100% natural breathable fibers and contain NO synthetic filling. The fine merino wool lining helps naturally in regulating baby’s body temperature, keeping baby warm in winter and cool in summer.

Woolino sleep bags are recommended to use in room temperatures 63-77F (17-25C). Simply adjust the layers of underwear or sleepwear worn beneath the sleeping bag to suit the nursery temperature. You can find our suggested dressing guidelines on the back of the room thermometer that comes with every sleep bag.

What is the difference between Woolino Ultimate (universal size) and Woolino Basic Baby Sleep Bags?


Both collections have same weight fabrics, Merino wool lining and organic cotton outer. The differences are:

Woolino 4 Season Ultimate Baby Sleep Bag has universal sizing: 2m-2yr, underarm snaps for adjusting the size of the armholes, travel slots for use in car seats, strollers, bouncers etc., & both shoulder snaps.

Woolino 4 Season Basic Sleep Bag has simpler design: no snaps and no travel slots; it comes in traditional sizes: 0-6, 6-18, 18-36 months.

When can my baby start using Woolino Ultimate Baby Sleep Bags in size 2m-2yr? How long will my baby fit in this Woolino sleeping bag?

Woolino Ultimate Baby Sleep Bags provide an excellent value as they are designed to fit an average size baby from about 2 months up to 2 years of age. You may start using your sleeping bag when you feel your baby is too big to be swaddled and is breaking out of it. Please use the under-arms snaps to adjust the fit for smaller babies. Our minimum recommended weight is 10lb. or 4.5 kg.

When should I use the under-arm adjustment system?

In general, you need to use the under-arm snaps for babies up to 6 months old. However, this depends on baby’s size, so for smaller babies you may have to use them longer. Please keep in mind that the underarm snaps are to be used for safety reasons, so that the sleep bag fits snugly around baby’s upper body and doesn’t climb up baby’s face.

This sleep bag looks big on my 2-month old, should I be worried about the extra length?

Woolino Ultimate Baby Sleep Bags are designed to fit an average size baby from about 2 months up to 2 years of age. The minimum recommended weight is 10lb. or 4.5 kg. This sleep bag has under-arms snaps to adjust the fit for smaller babies, so it fits snugly around baby’s body and doesn’t climb up baby’s face.

The length of the sleep bag is not an issue as long as the bag is well-fitted around your baby’s body. When it’s used on a 2-month old baby, folding the bottom up can only reach baby’s belly. Also, at this age, babies do not have sufficient body strength to lift all the material at the bottom up. The weight of the sleep bag helps in this too.

The bottom of the sack is designed to be roomy & grow with your baby. It also allows baby to move and kick inside the sack promoting healthy hip development.

Do I need more than one Woolino sleeping bag?

Yes, we recommend having two Woolino baby sleeping bags. It is always useful to have a spare sleep bag when one is being washed, to keep at grandparents' place or if baby requires a quick change in the middle of the night. Please enter code BOGO20 at checkout to receive our buy one item, get one item 20% off promotion. This promotion cannot be combined with any other offer.

Won’t wool itch my baby’s skin?

Absolutely not. We use only superfine merino wool, which unlike the traditional wool, feels like silk against baby’s delicate skin. In fact, because of its softness and unique breathability, it is perfect for helping treating conditions such as heat rash and eczema.

Isn’t merino wool too hot for warm temperatures/climates?

Our merino wool baby sleeping bags are perfect for year-round wear in nurseries with room temperatures 63-77F (17-25C). Simply adjust the layers of underwear or sleepwear worn beneath the sack to suit the room temperature. Merino creates a micro-climate around your baby’s body, gaining or losing heat as required to produce warmth in cool conditions and enhance cooling effects in warm conditions.

Woolino merino wool sleep bag seems rather thin, should I worry whether it’ll keep my child warm?

Merino provides warmth without having to be bulky. Unlike traditional wool, the finesse of the Merino fiber allows for a very fine spun yarn and knit fabric. Because of the way fine Merino fibers are crimped together, it has greater density than other fibers, which allows it to retain heat better than other thicker fabric. 

Although every baby is different, as a general guideline, Woolino sleep bags are recommended for use in room temperatures 63-77F (17-25C). Simply adjust the layers of sleepwear worn beneath the sleep bag to suit the temperature of your nursery. You can find our suggested dressing guidelines on the back of the included room thermometer.

What should my baby wear when sleeping in a Woolino 4 Season Sleep Bag?

We recommend sleepwear made of natural and breathable fabrics like cotton or merino wool. Please refer to the dressing guide we provide (also on back of your Woolino room thermometer) as general recommendations on how to dress your baby depending on the room temperature. Woolino pajamas are ideal for layering or to wear inside a Woolino sleep bag. The temperature in most rooms will rise and fall throughout the night, and the merino fiber has the remarkable ability to regulate your baby's body temperature.

How do I know if my child is hot or cold?

Please check if your baby is hot or cold while sleeping by touching her tummy or behind her neck. Touching baby’s hands and feet are NOT good indications of their actual body temperature.

Why don’t the sleeping bags have sleeves? Won’t my child get cold?

Our baby sleeping bags are sleeveless to ensure air circulation around baby’s chest. Babies that sleep with traditional sheets and blankets rarely sleep with their arms underneath the blankets. We recommend layering under-garments to ensure your child is perfectly comfortable in their sleeping environment. It is normal for babies to have cold hands and feet due to their still-developing circulation systems and it is not an indication that they are cold. Checking behind baby’s neck or his/her tummy will give you better indication of baby’s body temperature.

Woolino sleep bags sizing chart

Does the sleep bag need to be washed before the first use?

It is not required to wash your Woolino sleep bag before wearing. When you wash it, please follow the care instructions carefully.

Pajamas and clothing sizing chart

Merino wool is naturally stretchy. It has ability to expand and return to its original size so you may find our garments fit your child for longer than other non-merino garments. Our garments are cut on the generous side for a comfortable fit and to accommodate cloth diaper wearers.

How should I care for my Woolino sleep bag?

Merino wool by nature is self-cleaning and does NOT need to be washed as frequently as other fabrics. To refresh and reduce washing, turn garment inside-out and air often.

• MACHINE WASH: Close zipper. Use gentle wool cycle, on LOW temperature, 100°F /40°C max. Gentle spin
• Use wool approved detergent ONLY - we recommend Kookaburra (available at Woolino.com), a plant based alternative to "traditional" detergents
• Do not soak or bleach. Avoid fabric conditioners and softeners
• Use minimal amount of detergent as it may increase felting and pilling over time
• Hand wash: Gently soak and squish in lukewarm water. Do not agitate, wring, or rub wool against wool
• DRY FLAT when possible. When washed, Merino doesn’t feel very damp and dries very quickly. Simply place the garment over a drying rack and dry flat away from direct sunlight or any direct heat source (radiator). You may also tumble dry it on “No Heat” setting