PREMIUM FABRICS FOR BEST COMFORT - The award-winning 4 Season® Ultimate Baby Sleep Bag keeps your baby at a perfect temperature throughout the night, year-round. That means there’s no need to worry about which weight sleeping sack to use, or whether your baby will be too hot or cold while sleeping – they’ll always be just right!
SAFER, BETTER, AND LONGER SLEEP - Made with super-fine and supremely breathable merino wool, it helps keep your baby warm when it’s cold and cool when it’s warm. That temperature regulation means that your baby will sleep comfortably throughout the night– and that means a better night's sleep for you too. The cuddly-soft organic cotton outer adds to the comfort as it's perfect for the most delicate skin.
THE ONLY SLEEP BAG YOU NEED – With a universal size that fits babies from 2 months to 2 years, there is no need to worry about buying different sleeping bags as your little one grows or as the seasons change. You only need one Woolino sleep bag, right up until your baby turns two! And for toddlers, we’ve got you covered too, with a size for ages 2-4 years.
Premium natural fabrics Silky-soft hypoallergenic merino wool lining and the finest organic cotton outer.
4 Season use Unlike other brand sleep sacks that come in either winter or summer weight/TOG rating, the Woolino 4 Season Sleep Bag can be used year-round. It’s suitable for room temperature 63-75F (17-24C). Because of merino’s unique ability to regulate body temperature, it helps keep your baby warm when it's cold and cool when it's hot.
Grows with your baby It has a universal size so it can be used for babies 2 months up to 2 years old. For smaller babies, simply close the underarm snaps to adjust the fit. Toddler size fits from 2 - 4 years.
Excellent value You don’t have to buy a different sleep bag every few months. Woolino Ultimate 4-Season Sleep Bag is the only baby sleep bag your baby needs, in winter or summer, until they turn two years old.
Designed to be practical It features double shoulder snaps and a two-way side zipper, so it opens up completely flat for easy dressing without waking the baby. For easy nighttime diaper changes, you can open the bottom only. Zipper-pull guards protect baby's skin and discourage baby from chewing on the zipper pull.
Travel friendly A closable seatbelt opening allows for easy transfer between stroller, car seat, and crib, so you can keep your baby’s sleep routine intact while on the go.
A safer alternative to loose blankets Helps your baby stay covered through the night, replaces loose blankets in the crib, and promotes back sleeping.
Free Nursery Thermometer with a dressing guide included (baby size only).
Free shipping in the USA (Expected Delivery: 3-6 Business Days) on orders of $95 USD or more.
VIP Shipping: Your order is processed within 1 business day, even during high-volume periods. Enjoy faster delivery (estimated 2–4 business days) for a flat rate of $10 USD, available at checkout.
Express international shipping (Expected Delivery: 2-5 business days) starting at $14.99 USD.
Additional information about our shipping policy can be found here.
Machine wash on low (100°F max), use wool or mild detergent. Close zipper. Can be tumble dried on No Heat or Air Dry setting. Hang to dry whenever possible. To refresh and reduce washing, turn garment inside-out and air often.
We do not recommend sizing up.The sleep bagshould be well-fitted around your child's upper body for a safe and secure fit. We recommend using our sizing guidelines to determine the correct size based on your child's age, height, and weight. Your baby should not be below the minimum recommended weight.
Certifications
Setting the standard for textile safety, from yarn to finished product, Woolino sleep sacks bearing the OEKO-TEX® STANDARD 100 label (23.HUS.59156, Hohenstein HTTI) have passed safety tests for the presence of harmful substances.
Woolmark® and RWS certified merino wool (Responsible Wool Standard - cruelty-free, mulesing-free wool);
GOTS certified organic cotton.
Awards #1 rated and #1 selling merino wool baby sleep bag in US and Canada and winner of 2021 Cribsie Award, Creative Child and Baby Maternity's 2012 & 2018 Top Choice of the Year Award, 2017 Eco Excellence Award, 2016 Green Scene Mom Award, and Mom's Choice Award.
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. They are made from 100% natural breathable fibers and contain NO synthetic filling. Therefore, they do not have a fixed TOG. 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 be used in room temperatures 63-75F (17-24C). Simply adjust the layers of sleepwear worn under 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 baby 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.
Woolino sleep bags sizing chart?
We do not recommend sizing up.The sleep bagshould be well-fitted around your child's upper body for a safe and secure fit. We suggest using our recommended sizing guidelines to find the correct size based on your child's age, height, and weight.
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.
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 63-75F (17-24C). 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.
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.
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.
Why does wool smell when it gets wet?
There is an odor associated with wet wool, sometimes described as a "wet dog", "burned", or "perm" smell. This particular smell of wet wool is present because we use natural merino wool that has been minimally processed in order to preserve the lanolin content inside the wool.
Lanolin is naturally present in merino wool and is responsible for giving wool all of the great properties that we love: wicks away sweat, resists stains, feels soft to the touch, stays elastic, and resists bacteria and odors. Wool is a natural product. Even if you have multiple products, one may have a higher lanolin content than the other, accounting for a difference in smell.
You should not notice this smell at all when the product is completely dry. Over time, the smell will be less and less noticeable after washing as the lanolin content in the wool dissipates.
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, air the garment often.
Machine wash: Close zipper. Wash on Low, 85°F /30°C max
Use wool or mild detergent.
Line-dry clothing and blankets. Sleep bags can be tumble dried on No Heat or Air Dry settings.
How to remove stains from wool?
Stains should be treated immediately. Do not apply any form of heat, as this tends to fix most stains making them more difficult to remove. Rinse the stain immediately and thoroughly in cold water. Then, apply one of these two homemade stain remover mixtures that we recommend:
The preferred option is a mixture of liquid laundry detergent and a few drops of white vinegar. Cover the stain with the mixture and allow the liquid to sit on the stain for at least an hour. Blot the stained area gently with a cloth before rinsing thoroughly with clean water. Repeat if necessary.
Another option is a mixture of one part (1 Tsp) dish soap and two parts (2 Tsp) Hydrogen Peroxide (3%). Apply some of the mixture over the stain and let it sit for several hours. Wash afterwards as usual.
When ready to wash, check the product care tag for best results. Following our recommended care instructions will ensure the best possible wear while maintaining & prolonging the life of your Woolino.
Here's a link to The Best Ways to Remove Stains from Your Wool Clothes provided by Woolmark. It contains a comprehensive list of different types of stains and a step-by-step guide for removal: https://www.woolmark.com/care/stain-removal-wool/
Please Contact Us and we'll answer your question promptly.
A study done by the University of Sydney has found that a better night's sleep is achieved when sleeping in wool.
Fine merino wool is the perfect fiber to have next to your child's sensitive skin. It's cuddly soft and uniquely temperature regulating - creates a perfect micro-climate for safer and longer sleep.
Safe & Certified
Crafted from premium natural materials, Woolino sleep sacks are certified by trusted standards (OEKO-TEX 100, Woolmark, GOTS, and RSW) to ensure the highest level of safety, comfort, and quality for your little one.
Grows With Your Baby
Designed as a universal size, it fits babies from 2 months to 2 years (toddler size fits from 2 - 4 years). For smaller babies, simply close the underarm snaps to adjust the fit. No need to buy a new size sleep sack every few months!
My baby absolutely loves this sleep sack. Every other sleep sack before this he woke up with a sweaty back, so we switched to Woolino and he no longer is sweating all night long. The size range and four season wearability makes it well worth the money and I will be purchasing more!
Alexis G.5/5Verified
We love it and so does our baby! Takes the stress away from figuring out what TOG to use depending on weather / room temperature.
Emily B.5/5Verified
Love!!!! We have two and they are amazing. Very nice quality and keep our baby warm but never too warm. Definitely worth the money since they can be used for so long and year around! It keeps sleep sacks simple and not complicated to figure out (temperature and sizes).
Amelia I.5/5Verified
Woolino offers the perfect sleep sack. We were gifted one, and I ended up purchasing another because our son loves them so much. We tried a few other sleep sacks, and this is the only one he always seems comfortable in. I wouldn't recommend another sleep sack besides this one. It's worth the price.
Kaitlin S.5/5Verified
We love the woolino! The shoulder snaps are super convenient and we love how long our baby will be able to wear it. We will definitely be investing in another.
Susannah P.5/5Verified
It is really well made and she seems to sleep really well in it!
Jessica B.5/5Verified
Our baby loves the Woolino sleep sack! So cozy, but not too warm on summer nights either. The hot air balloon print is adorable too!
Jennifer S.5/5Verified
This sleep sack is amazing!! We love the seat belt slots because a lot of times our kids know it’s time to sleep when their sleep sack goes on, and since we travel a lot, it’s nice to be able to have them wear it on long car rides. I also love the extra space in the arm holes. It’s so nice to only have to buy one sleep sack for ages 2-24 months. We bought way too many for our first son!
Erin L.5/5Verified
My baby loves this sleep sac. It seems to keep him comfortable no matter the weather and the quality is amazing ! It is really big but also that is great as it will allow us to use it for the 2 years it’s states
Nicole S.5/5Verified
Love how easy this sleep sack is and how versatile and comfy it is too! Little one slept for 40 minutes on the play mat for the first time
Lisa W.5/5Verified
The sleep sack is buttery soft, very functional and well-made. We just transited her out from swaddle up. We were a bit concerned that she would not sleep well and mentally prepared that it would take couple of nights for her to get used to the sleep sack. But I think she loves it and she slept through the night even the very first night without a swaddle. The design is super cute. We are first time parents and probably wasted some money here and there buying unnecessary stuff. However, we think the sleep sack is totally worth it. We just bought another one with the snowboarder print per Dad’s request. Hoping the one with universe print for 2 month-2 year will eventually be back in stock ( per Dad’s request too)
Chailu Q.5/5Verified
We love it! At first, I was hesitant to purchase because of the price. But, my baby runs very hot and this sleep sack is always the perfect temperature for him.
Shelby I.5/5Verified
This sleep suit is worth the price tag! I appreciate the natural fibers and that this is the only sleep suit I will need to buy for my daughter. It saves me money in the end! I also appreciate the room thermometer that came with the sleep suit, it helps me know the temperature of her room and how to dress her accordingly.
Hannah P.5/5Verified
I and my daughter have loved this sleep sack! I have noticed that she sleeps much more comfortably and it gives me peace of mind to know that she will not be too hot or too cold! After a month or two some of the stitching started coming apart (as shown in the photos) and got worse as time went on with the seam binding ripping off. It was so easy to file a warranty claim and I got a replacement quickly! I would highly recommend going with Woolino when choosing a sleep sack for the top tier quality and the amazing customer service! I will be recommending them to everyone!
Stacy D.5/5Verified
I’ve got a tall baby and I also value natural fibers, so this is the perfect sleep sack for my little guy. He was growing out of other brands, so I am happy to invest in these knowing they will be the only sleep sacks I will need for a long time. They are super soft, and I love that they came with a thermometer card and advice on what to put underneath them. Very helpful! Would highly recommend and will likely buy more!
Katie D.5/5Verified
The Woolino Ultimate 4 Season Baby Sleep Sack has been one of my favorite baby essentials! The merino wool and organic cotton feel incredibly soft, and I love that it helps keep baby comfortable without constantly worrying about overheating or getting too cold. The two-way zipper makes nighttime diaper changes so much easier, and the quality is outstanding. I also have to mention their customer service—it was absolutely exceptional. I had a delivery issue, and their team responded quickly and resolved it immediately with no hassle at all. Best of all, it’s a long-lasting investment that works year-round and grows with your little one. Absolutely worth every penny for better sleep and true peace of mind! I absolutely would recommend and will (very soon) be repurchasing!
Tammy K.5/5
We got a hand me down Woolino from a friend and had to buy a back up. She used it for 2 kids and you would never know. These hold up so well and are extremely comfortable. I wish I knew about these with my other 3 kids. My son loves this sleep sack he grabs the extra material and cuddles it, but safely since it can not get close to his face.
Kristi F.5/5Verified
Love it! We used the 4 season classic with our first baby and the ultimate sleep bag with this baby. I think I prefer the ease and quickness of the classic. This feels nice and secure and fit to our baby but it's annoying to have to do all the buttons every time I put it on. It's beautiful though and I love the print. It's so so soft. Love our woolinos!
Casey P.5/5Verified
This has been the first and only sleep sack that my baby has been able to successfully fall asleep in and stay asleep independently in her own crib. We will be purchasing another just to have on rotation. Well worth the price considering she will be able to use them until she is 2. We will also use these for our next child as well.
Hannah B.5/5Verified
Woolino is one of my best purchases. We live in a rather hot climate but our house temperature fluctuates a lot during the night and I always had trouble on what was the best pyjamas or sleep sack. Now I am care free even if its 16 or 22 celcius🙏
Eleni K.5/5Verified
The temperature of our house fluctuates a lot! I love knowing that my baby will stay comfortable all night. It’s also a relief knowing that he can wear this until he grows out of a sleep sack! No need to keep purchasing larger sizes or different TOGs. It’s so soft to the touch. Ive found it really easy to undo for middle of the night diaper changes.
Taylor B.5/5Verified
Our daughter is so comfy and happy in this sleep sack. She tends to run hot and she never gets overheated in it!
Tracy F.5/5Verified
These are the perfect sleep sacks!!! Hot or cold it adjusts to keep baby comfortable. The sacks are lightweight and don’t feel bulky like some and still comfortable to burp babies in the middle of the night or to change diapers, the zipper goes all around the bottom also, easy to put on and allows babies to move freely. 🩵🩵
Amber B.5/5Verified
My girl is SUPER tall and we have gone through sleep sacks like it’s nothing because of it!! This one is perfect for her and for my wallet because she has so much room to grow into!! Her room doesn’t hold a lot of heat which has made me panic each night since she’s born on if she’s cold, but she has slept soundly and I have to with the peace of knowing she’s ok either way! We love it!!!
Mckenna R.5/5Verified
Love it! So soft and keeps my baby comfortable all night.
Yongnan P.5/5Verified
We love our woolino sleep sack! It’s such great quality and baby sleeps so comfortably in it!
Laura M.5/5Verified
He had an amazing night’s sleep and woke up happy as!
Amanda W.5/5Verified
The material is great quality and my daughter sleeps well with it!
Mubin M.5/5Verified
I dressed my 1.5 month old baby with the Woolino sleep slack, and to my surprise he's able to sleep soundly, waking every 3 hours the first night with it on. It really is weighted and super soft to the touch. I was worried about overheating, but so far he hasn't cried where removing it would calm him again.
Stephanie Alexis G.5/5Verified
My baby loves all woolino sleep bags ♥️
Olena Z.5/5Verified
We absolutely love our Woolino Ultimate Sleep Sack! The quality of the material is amazing, and it’s given us so much peace of mind. We were looking for a sleep sack that would keep our baby comfortable without worrying about her getting too hot or too cold—and this has been perfect.
After our daughter experienced a febrile seizure, having something temperature-regulating became especially important to us. Since using this, we haven’t had to worry, which has been such a relief. We also love that she can use it up to 2 years old—it’s a great long-term investment!
Our home temperature tends to fluctuate, and this sleep sack has really helped ease our minds. Best of all, our girl absolutely loves it and sleeps so well in it. Just look at that smile!
We love seeing our happy girl in her Woolino sleep sack and highly recommend it.
Cassandra R.5/5Verified
We bought our baby’s first Woolino second-hand and fell in love with it, we knew immediately we’d need another! Our baby’s room tends to run warm but the Woolino helps to keep her comfortable. I’ve already bought another one for a friend as a baby shower gift.
Kennedy G.5/5Verified
Love!! Perfect for those cold days between the car seat and stroller. We also use at night and I love how amazing the quality is.
Breanne B.5/5Verified
I’ve been in childcare for over 7 years and I just started using these for my own son, and truthfully they are now my favorite sleep sacks. So much that I bought a second one! You can tell the quality is top notch, and the fact that it’s all season AND can grow with baby makes it well worth the money.
Rachel P.5/5Verified
We LOVE this sleep sack. This is our second child going through them but I just wanted a backup. We have 2 for home and one for daycare. I also buy one for all my friends baby showers and they switch their sleep sacks to woolino. The 2 year sizing is the best, side sippers and just all over cozy feeling with temperature regulation.
Nicole M.5/5Verified
Really great quality!! Can see this lasting years!
Stephanie S.5/5Verified
Love this! We feel so much better knowing that this will regulate his body temperature. Already buying back up because our baby loves it!
Abbiegail H.5/5Verified
Such great quality keeps its structure after washing! My little loved it!
Elizabeth S.5/5Verified
The indigo Woolino I recently purchased was for my nephew as he welcomes a new little one. However, it's only because my little guy has his own that was purchased for him and we absolutely love it!
Tori S.5/5Verified
Our 22 month old does not like blankets so we knew we wouldn’t be transitioning to those for sleep anytime soon. The smaller version was a life saver for us so it was a no brainer when we found out they had a toddler version. Will recommend these to everyone and continue to use them with our second!
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