This is the Adidas Ultra Boost size chart for men and women in 2021.
Every year, Adidas drops another Ultra Boost silhouette, and every year, it seems to get just a little bit more Boost.
With the 21st iteration, it looks like Adidas went crazy with Boost.
Without further ado, let’s get right into the size chart…
Adidas Ultra Boost Size Chart
Men’s Ultra Boost Size Chart
|Heel – Toe
|Heel – Toe
|4.5||8.9″||22.5 cm||4||36 2/3 *||225|
|5||9.0″||22.9 cm||4.5||37 1/3 *||230|
|6||9.4″||23.8 cm||5.5||38 2/3 *||240|
|6.5||9.5″||24.2 cm||6||39 1/3 *||245|
|7.5||9.8″||25.0 cm||7||40 2/3 *||255|
|8||10.0″||25.5 cm||7.5||41 1/3 *||260|
|9||10.4″||26.3 cm||8.5||42 2/3 *||270|
|9.5||10.5″||26.7 cm||9||43 1/3 *||275|
|10.5||10.9″||27.6 cm||10||44 2/3 *||285|
|11||11.0″||28.0 cm||10.5||45 1/3 *||290|
|12||11.3″||28.8 cm||11.5||46 2/3 *||300|
|12.5||11.5″||29.3 cm||12||47 1/3 *||305|
|13.5||11.9″||30.1 cm||13||48 2/3 *||315|
|14||12.0″||30.5 cm||13.5||49 1/3 *||320|
|15||12.4″||31.4 cm||14.5||50 2/3 *||–|
|16||12.7″||31.8 cm||15||51 1/3 *||–|
|17||13.0″||32.6 cm||15||52 2/3 *||–|
|18||13.3″||33.5 cm||17||53 1/3 *||–|
|19||13.7″||34.3 cm||18||54 2/3 *||–|
|20||14.0″||35.2 cm||19||55 2/3 *||–|
Women’s Ultra Boost Size Chart
|Heel – Toe
|Heel – Toe
|5.5||8.9″||22.5 cm||4||36 2/3 *||225|
|6||9.0″||22.9 cm||4.5||37 1/3 *||230|
|7||9.4″||23.8 cm||5.5||38 2/3 *||240|
|7.5||9.5″||24.2 cm||6||39 1/3 *||245|
|8.5||9.8″||25.0 cm||7||40 2/3 *||255|
|9||10.0″||25.5 cm||7.5||41 1/3 *||260|
|10||10.4″||26.3 cm||8.5||42 2/3 *||270|
|10.5||10.5″||26.7 cm||9||43 1/3 *||275|
|11.5||10.9″||27.6 cm||10||44 2/3 *||285|
|12||11.0″||28.0 cm||10.5||45 1/3 *||290|
|13||11.3″||28.8 cm||11.5||46 2/3 *||300|
|13.5||11.5″||29.3 cm||12||47 1/3 *||305|
|14.5||11.9″||30.1 cm||13||48 2/3 *||315|
|15||12.0″||30.5 cm||13.5||49 1/3 *||320|
- Related: Adidas Yeezy 380 Size Chart & Review
Adidas Ultra Boost Review
Starting things off, the Adidas Ultra Boost 21 officially released on January 28th and February 4th, 2021.
The UltraBoost 21 replaces last year’s UltraBoost 20 and sits alongside the UltraBoost DNA which is kind of their legacy model.
- Related: Adidas UltraBoosts vs NMDs
The retail price for the Ultra Boost 21 is the same that’s it’s been for the last couple of Ultra Boost sneakers and that’s $180.
I think it’s fair to say that the Ultra Boost always has been positioned as a premium running sneaker. When I first saw images of the Ultra Boost 21, I was floored by the amount of Boost it looks like it has in the heel. (pic 1.38)
It really looks like it has by far the most Boost that they’ve ever put in an Ultra Boost sneaker. While that is true, there is some caveats to that.
But the real question that a lot of you all have is how comfortable is the UltraBoost 21 sneaker and is it good for performance running?
Let’s find out…
Sizing & Fit
So, do the Adidas UltraBoost run small, big, or true to size?
As far as sizing and fit, I have narrow feet and the UltraBoost 21 does run true to size.
If you have wider feet, it might not hurt to go up half a size. However, if you own any of the previous 19 or 20s, the fit is very similar to those.
But at the end of the day, the best way to know if a shoe fits is just to try it on before you buy it.
Here’s the ultimate Yeezy sizing guide of all the Yeezy models released so far. Make sure you check it out.
- Related: Adidas NMD Size Chart & Review
As far as performance running is concerned, the UltraBoost 21 is still definitely a neutral running sneaker. However, it does have a lot of cushion under your foot.
So, if you’re looking for a very heavily cushioned running shoe that’s still very responsive, the UltraBoost 21 is a great way to go.
Comfort aside, I love the way that this Boost midsole is sculpted. Yes, I don’t love the fact that it’s kind of lying to you about how much Boost is underfoot, but I do really love the way that it’s shaped.
It looks fast, it looks speedy, and it looks is going to bounce you over any obstacle that gets in your way. I especially love the speed lines that are pressed into the middle of the midsole and I feel like they give this shoe a lot of character.
Adidas Ultra Boost 21 vs Ultra Boost 20
Right off the bat, you can see that there are some pretty dramatic changes between the newest model and the previous model.
It looks like Adidas is making the Ultra Boost 21 a much more apparent performance model and separating it from the sort of lifestyle aesthetic the 20 and 19 had.
I know the 20 and the 19 definitely look a lot more performance and running-driven than any of the previous UltraBoosts and they kind of lost that cool lifestyle aesthetic that the older UltraBoost had.
But it’s become very obvious with the UltraBoost 21 that the Ultra Boost line is now headed fully towards performance aesthetics.
Honestly, I kind of feel that that’s a good thing because the 19 and the 20 didn’t really seem to fit in any categories visually.
They didn’t look as good as the other lifestyle UltraBoosts and they didn’t really have that sort of aggressive performance look that some other running shoes have.
So, I think whether you like the new design direction of the UltraBoost or you don’t, I think it’s the right move for Adidas. This really gives the Ultra Boost line a lane and makes this shoe look like what it’s supposed to be.
If you had to guess what this sneaker was from just looking at it, I think you would understand the idea that they’re trying to communicate which is an aggressive running performance shoe.
- Related: Adidas Yeezy 700 Size Chart & Review
Primeknit vs PrimeBlue
Aside from the overall shape and silhouette change, the UltraBoost 21 does have some notable performance improvements that have to do with materials and new design details.
Diving into some of those details, around the toe of the sneaker, you’ll notice that Adidas is using a brand-new knit material called PrimeBlue.
PrimeBlue is the new version of Adidas’ Primeknit that utilizes primarily recycled materials like the Parley Ocean plastics.
What I really like about this new PrimeBlue upper on the Ultra Boost 21, in particular, is that because they made it a little bit thicker than the previous PrimeKnit, it really contains your foot very well and keeps your foot in place and locked in so that you have no slipping issues.
That seems to be the case even without actually tying the laces. Even if you wear this shoe unlaced for just lifestyle wear, you’re not going to have any issues whatsoever.
Of course, being a brand-new Ultra Boost silhouette, you do have a new knit pattern which seems to be similar to previous UltraBoost sneakers except it kind of extends all the way up to the midfoot of the sneaker.
Around the edges of the ventilation holes, you have these heat-pressed details to add a little bit more structure and aesthetics as well.
Now let’s move to the part of the UltraBoost 21 that I think most people are interested in…
According to Adidas, the UltraBoost 21 has 6% more Boost than the UltraBoosts 20. If you look at them back-to-back, it really looks there’s significantly more Boost in the 21 than in the 20. Unfortunately, it’s kind of visually deceiving.
While there is more Boost in the UltraBoost 21 over the 20 and significantly more Boost than the UltraBoost DNA, a lot of the Boost looks like it’s under your foot, but it really isn’t.
On the heel of the 21, it looks like your foot is on top of an inch and a half of Boost, which is obviously a crazy amount. However, there are two reasons why this Boost looks a lot thicker and a lot more plush than it actually is.
The first is that the heel of the shoe actually has a pretty significant curve upward which, to be honest, is really great for running because it makes your movements a lot more smooth.
The second and the most disappointing reason is that your foot actually rests deeper into the shoe than you would expect.
When I first tried the 21, I was expecting mind-blowing levels of Boost. I was expecting my foot to feel like it was just bouncing on top of a cloud. It still feels great and still feels Boost, but it doesn’t feel that much more Boosty than really any other UltraBoosts.
The reason for that is because when your foot actually goes into the shoe, the Boost in the heel is just cupping your foot and it’s not under your foot. Because of that, it doesn’t really do anything more special.
So, your heel is pretty much only on about the same amount of Boost on the UltraBoost 20 and 19. Again, it’s still an incredibly comfortable shoe and it’s probably the most comfortable UltraBoost ever. However, it just doesn’t have as much Boost underneath your foot as it looks like it would.
Is that really that big of a deal? Not really.
You’ll notice that the outsole has been completely redesigned.
The rubber panels on the outsole are made up of Continental rubber. Adidas has been partnering with Continental for years and that’s a good thing because the outsoles that they’ve created together last a very long time.
Adidas LEP Torsion System
But that’s not the biggest change. The largest change is the brand-new torsion system called Adidas LEP. What LEP stands for is Linear Energy Push.
Apparently, what this new torsion system does is reduce a lot of the torsional flexing while still giving you a lot of responsiveness.
Also, this new torsion system acts even more spring-like than the previous torsion system and literally gives a sort of spring to your step.
Moving back in the sneaker, you get to the semi-translucent TPU midfoot cage which is really a throwback to the original UltraBoost.
Both the UltraBoost 20 and 19 had a midfoot cage which was really just one piece and extended up from the midsole. But this time around, it looks a lot more like the UltraBoost DNA’s midfoot cage.
You’ve got three individual stripes. Rather than extending the stripes down to the midsole, they’re actually sewn about maybe 5mm up from the midsole on to just the PrimeBlue upper.
I’m not totally sure why they decided to do that, but it feels fine on foot and I think it actually looks really nice.
Laces, Tongue, Ankle
Weaving to the midfoot cage, you’ve got these flat gray laces which, of course, match the upper.
What’s interesting is that when first get the shoe, the top lace eyelet is actually left untied to just allow you to customize the fit however you want.
Because this knit upper is a one-piece bootie construction, that means that there is no separate tongue. It’s really more of a sock going over the top of your sock than a regular sneaker’s upper.
Around the top of the ankle opening, you’ve got this exposed knit edge which doesn’t rub against your ankle.
Moving inside this shoe, you’ve got this really nicely padded neoprene portion which feels really great against your heel.
Then from the midfoot to the toe, there really isn’t any padding and your foot is just against the Primeknit.
You’ve got a much thinner heel counter than you’ve had on the previous UltraBoosts. Unlike the UltraBoost 19 and 20, it doesn’t actually wrap over on to the Boost midsole.
A few things that I really like about the heel area of the UltraBoost 21 is that it extends up really nice and high so it can act as a pull tab (pic 8.24)
Even though it’s this high, these shoes don’t really irritate your Achilles tendon at all, which is great. It also has a lot of structure so you never feel like you’re not secure in the heel.
Not only that, apparently there is no version or new polyester used anywhere on the upper of the shoe.
I’ve got to say it is so cool that Adidas is really focusing on using recycled materials especially in their mainline sneaker products like the Ultra Boost, the Stan Smiths, the Super Stars, and more.
For a while, they were just using it on special edition Parley sneakers, but now this sort of Parley Ocean plastic material is getting woven into their everyday sneakers, which is so cool.
That really seems to be the trend among a lot of other major sneaker brands. They all seem to be focusing on sustainability.
But I’m going to give Adidas some credit where it’s due because they really did seem to be the first company to go full tilt on using recycled materials before really anybody else, at least any of the major brands.
I know there are some smaller brands that are focusing on only using recycled materials and those brands are awesome, but as far as the big three, Adidas did really seem to be the first one to really focus on sustainability.
If this upper is made up of plastic bottles, how does it feel? Does it feel as good as regular knits?
Comfort & Breathability
Honestly, as far as breathability and comfort of this PrimeBlue upper goes, it feels great. The upper feels really nice and soft on your foot. It’s definitely a sock-like fit.
It’s a little bit thicker than regular Primeknit, but I don’t think that’s because of the materials that they’re using. I think that’s because they actually meant to make it thicker.
It’s also very breathable. But even though it’s cold outside, your feet still do get warm when you’re running. You really won’t have any overheating issues at all.
Which one is better?
So, with all of those performance improvements, is the UltraBoost 21 a better sneaker than 20?
Overall, I’d have to say yes. Even though the Boost in the midsole isn’t that much thick than you would think that it is, it’s still very comfortable and it’s still softer than the UltraBoost 20.
The PrimeBlue knit used on the upper definitely focuses more on sustainability while still containing your foot and still being very breathable and comfortable.
The LEP torsion system on the bottom reduces torsional flex while still giving you a little bit more responsiveness.
Yes, all of these performance changes are excellent and they definitely do help you with your run, but it’s not going to be like a ground-breaking difference between the two sneakers.
I think the biggest difference between the UltraBoost 21 and 20 is really the design. While that’s not a bad thing because design is very important especially when it comes to something that you’re actually wearing on your body, it’s really the biggest difference.
So, I guess my verdict is if you have a pair of UltraBoost 20 that you run in and you’re happy with it and they’re still in a great condition, stick with those.
However, if you’re looking to upgrade or you’re looking to get a new pair of UltraBoosts and you haven’t had a pair in a while, the UltraBoost 21 is definitely the shoe to go with.
Comparing the UltraBoost 21 to the 20, it doesn’t seem like it’s that great of a shoe, but that’s because the UltraBoost 20 sets such a high bar that the 21 is like just above that bar.
Even if you’re not a runner and you just love the aesthetic of this sneaker, you’re going to love the UltraBoost 21 for lifestyle wear because it’s incredibly comfortable.
This pretty much wraps up this Adidas Ultra Boost size chart, review, and comparison. Have you grabbed a pair of the UltraBoost 21? If yes, what’s your experience in the 21 compared to the 20 or even the 19?