Look at your hands while typing. Your fingers are responsible for dozens of keys, while your thumbs get… the spacebar.
Seems like a waste, doesn't it? Keyboard designers thought so too. Almost 50 years ago, they started experimenting with ways to give our thumbs more keys. Some tried to cram as many keys as possible under our thumbs, while others placed just a few along their natural movement.
But there was a problem: the more keys you added, the harder they were to reach and press comfortably.
So, how have thumb clusters evolved over the last 50 years? And are we any closer to finding the perfect design?
The two original approaches to thumb clusters
To understand how thumb clusters evolved, we need to go back to the 1970s.
One of the earliest approaches was the thumb block, pioneered by Maltron.
The idea was simple: give your thumbs more keys so they could take over functions that would otherwise require awkward finger movements, such as Backspace, Enter, Control, or Shift.
But there's a catch. Some keys are easy to press, while others require you to stretch your thumb or even move your entire hand. Packing so many keys together can also make it harder to distinguish them by touch.
So, in the early 1980s, another approach appeared: the thumb curve.
Instead of cramming as many keys as possible into a block, the idea was to arrange fewer keys along the natural arc of the thumb. This made them easier to reach and distinguish, at least in theory.
But, of course, there was a trade-off. Fewer keys meant fewer functions you could assign to your thumbs.
And that leads to the question keyboard designers have been dealing with ever since: how do you give your thumbs more keys without making them harder to use?
How thumb clusters evolved
Both approaches have survived to this day.
You can see variations of the thumb block in keyboards like the Kinesis Advantage, Ergodox, or Moonlander.
The thumb curve is especially popular among smaller ergonomic keyboards, such as the Corne or the Go60.
Some designs go in the opposite direction and use just two thumbkeys per side, like the Voyager.
But while fewer keys are generally easier to accommodate, they also limit how many functions you can assign to your thumbs.
So perhaps the answer isn't just how many keys you have or where you place them. Perhaps it's also about the shape of the keys themselves.
Thumbkey design isn't just about position
When you press most keys on your keyboard, you use the tip of your fingers. That's why standard keycaps are often concave: their shape helps guide your fingertips toward the center of the key.
But we don't use our thumbs quite the same way.
We often press thumb keys with the sides of our thumbs, so the raised edges of traditional keycaps can become uncomfortable.
So why not design keycaps specifically for thumbs?
That's something we explored when designing the original Dygma Raise.
Instead of regular concave keycaps, the Raise uses specially shaped convex thumbkeys with smooth surfaces that are more comfortable to press from different angles.
But there was another challenge. The design needed four keys per thumb, arranged in two rows. If both rows were at the same height, it would be easy to accidentally press one key while reaching for another.
The resulting arrangement makes it easier to move between the two rows without accidentally pressing the other one.
Another interesting solution can be found on the Keyboardio Model 100.
It also uses specially sculpted keycaps, but arranges them in a curved thumb cluster.
But there's still something left to solve: what if four keys per thumb aren't enough?
Can you add more thumbkeys without sacrificing comfort?
One keyboard that explores this idea is the Glove80.
It combines a curved arrangement with two rows of thumbkeys, giving you six keys per thumb. It's a clever way of fitting more keys around the natural movement of the thumb.
However, some keys can still be harder to reach than others, especially on the top row. In some cases, you may also need to curl your thumb to avoid hitting the top row when pressing a key in the bottom row.
We faced a similar challenge when developing the Dygma Defy.
The goal was to combine the number of keys of the thumb block with the natural movement of the thumb curve. To achieve that, we used a two-row design arranged in an arc.
Instead of standard keycaps, the Defy uses custom-sculpted convex keycaps that fit closely together while remaining distinguishable by touch.
Some have different shapes, others have beveled edges, and there are small gaps between them to help you navigate the cluster.
But does that mean everyone can comfortably reach all eight keys with each thumb?
Not really.
We all have different hand sizes, thumb flexibility, and typing habits. Some people find the outer keys more comfortable, while others prefer the inner ones.
The goal with the Defy was for everyone to find at least four or five keys they could comfortably use, even if they weren't the same ones for every person.
The trade-off of fitting more thumbkeys
There is, however, a price to pay for fitting so many keys into such a compact space.
We had to design very specific keycaps that sit extremely close together. So close, in fact, that you can't simply replace them with standard 1u MX keycaps, because they would collide.
And that's not ideal if you want to customize your keyboard with your favorite keycaps.
Still, we are incredibly happy with the Defy's thumb cluster. It's one of the features we're proudest of.
So, when it came time to design the company's next keyboard, you might expect us to use the exact same approach again.
But we didn't.
Why the Dygma Sonsei went back to four thumbkeys
The Dygma Sonsei has only four thumbkeys per side.
So, after spending so much time developing a thumb cluster with sixteen keys on the Defy, why go back to eight in total?
Designing a keyboard isn't simply the sum of individual features. It's about making everything work together.
The Sonsei was designed with a very different goal in mind: a compact, lightweight, low-profile ergonomic keyboard that you can take anywhere.
A keyboard you can use on your desk, at a small café table, or even on top of your laptop.
That meant every millimeter mattered.
We actually experimented with adding another row of thumbkeys using ultra-low-profile switches.
But that extra row would have made the keyboard larger and interfered with the trackpads of some laptops.
For a keyboard designed around portability, that was a compromise the team didn't want to make.
So, the Sonsei kept four thumbkeys per side.
We also redesigned the keycaps to maintain a comfortable shape while leaving enough space between them to use compatible standard low-profile keycaps if you prefer.
Does that mean we think four thumbkeys are better than eight?
Not at all.
Miquel loves having eight thumbkeys on each side of his Defy. But the Sonsei has different priorities.
Is there a perfect thumb cluster?
So, after almost 50 years of experimenting, are we any closer to finding the perfect thumb cluster?
We've certainly come a long way.
Keyboard design has evolved from simply putting more keys under our thumbs to carefully designing their position, shape, and height to make them easier and more comfortable to use.
But there's still no one-size-fits-all solution.
Because the perfect thumb cluster isn't necessarily the one with the most keys. It's the one that best fits your hands and your needs.
How many thumbkeys do you actually use?
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