Concept: Humanly Watch, the thinnest smartwatch we can imagine
A concept for a very thin smartwatch: a 5 mm titanium case, an AMOLED screen that stays black until you raise your wrist, three glances, no apps and about a week of battery.
The Humanly Watch is a concept for the thinnest smartwatch we can imagine: a flat titanium case about 5 mm thick, a screen that stays black until you raise your wrist, and three things to look at. The time, who is calling, and what is next. There are no apps, no watch faces to download and no health dashboard. It taps your wrist when one of a few chosen people needs you, and otherwise it is a thin piece of metal that tells the time.
Like the Humanly Phone and the Slate, this is a concept. We are a software studio, nothing here is for sale or in development, and every number is an estimate from public parts and teardowns rather than a prototype. We drew it because a watch is the device where "does less" is easiest to defend and hardest to build.
Where the idea came from
Mechanical watchmaking has a long tradition of extremely thin watches. Some of them are only a couple of millimetres thick, with the movement and the case merged into one plate. They are beautiful because every part had to argue for its place. Nothing is there by default.
Smartwatches went the other way. They grew thicker as they gained sensors, a brighter screen and a bigger battery to feed both. A typical smartwatch today sits somewhere around 10 to 12 mm, and sports models with large sensor domes on the back are thicker still. That is not a design failure. It is the honest size of a device that measures your heart, runs apps and stays on all day.
We wanted to ask the opposite question. If a smartwatch only needed to show three things and buzz for a few people, how thin could it get? We did not want to copy the look of any thin mechanical watch. The shape comes from our own mark: the rounded square of the orange "h", flattened into a case.
What it shows
The screen is AMOLED, and most of the time it is completely black, which on AMOLED means the pixels are off. It lights up in two situations only: when you raise your wrist and look, or when someone on your allow-list calls.
- The time. Large numerals and the date. That is the whole face. No complications, no step rings.
- Who is calling. The name of an allow-listed caller and a short haptic tap. You answer on your phone. The watch has no microphone or speaker, so it cannot take calls itself, and we think that is fine.
- What is next. Raise your wrist twice in a row and it shows the next event from your calendar, with how long until it starts.
Messages from the allow-list could appear as a name and a dot, without the text. Everything else stays on the phone. The watch has one flush button on the side that wakes the screen, and a long press silences the allow-list for the rest of the day.
The allow-list is the heart of it. You pick a handful of people, the same idea as the quiet slider on the phone concept. When one of them calls, the watch taps your wrist in a pattern you learn after a day or two. Nobody else can make it buzz. There are no app notifications at all, because there are no apps to send them and the phone does not forward them.
How 5 mm could add up
The case is a flat titanium shell with rounded corners, about 36 mm across. Titanium is stiff and light, which matters when the walls are this thin. The front is a flat sapphire cover, because a thin glass on a watch takes knocks against door frames all day.
- Sapphire cover, 0.5 mm. Flat, no curved edge, bonded to the case.
- AMOLED with touch, 0.4 mm. A small flexible OLED panel. Touch is there for dismissing a call, not for scrolling.
- Board, haptic and antenna, 1.1 mm. A low-power chip with Bluetooth LE, a basic accelerometer for wrist raises, and a thin linear haptic motor. The antenna has to sit behind a non-metal window, which is one reason the front is sapphire and not titanium edge to edge.
- Flat cell, 2.2 mm. A thin lithium-polymer pouch filling most of the case area.
- Titanium case back, 0.8 mm. Completely flat. No sensor window, no dome.
Charging is the detail we like most. Most smartwatches charge through the back, with a magnetic puck and coils or pins under your wrist. We moved two small charging pins to the lower edge of the case, so the back can stay one flat plate. A small cradle holds the watch on its edge at night. It is a slightly odd way to charge, and it saves the fraction of a millimetre that a coil and its shielding would take.
A week on a small cell
A cell 2.2 mm thick and about 30 mm square holds something like 200 to 250 mAh, depending on how much of the case area it can use. That is small even for a watch. The budget only works because the watch does almost nothing.
We used the method from A week on one charge. Sleep with the accelerometer listening for wrist raises is the steady cost. The screen is on for a few seconds at a time, perhaps three or four minutes a day in total, and it is mostly black. Bluetooth LE keeps a low-duty connection to the phone. There is no heart-rate sensor sampling in the background, which in that post was the single largest line for a simple watch. Our rough total is about 0.1 Wh per day, which puts a 0.8 to 0.9 Wh cell at around a week in real use. That is an estimate on paper, and Bluetooth behaviour on real phones is less tidy than a spreadsheet.
It pairs with the Humanly Phone concept, or with any ordinary phone through a small companion app. The companion app holds the allow-list and the calendar access. The watch itself stores almost nothing.
Spec sheet, on paper
| Case | Titanium, rounded square, about 36 × 36 × 5 mm (estimate) |
|---|---|
| Screen | Small AMOLED with touch, black until wrist raise or an allow-listed call |
| Front | Flat sapphire cover |
| Controls | One flush side button |
| Sensors | Basic accelerometer for wrist raises. No heart rate, no health suite |
| Feedback | Linear haptic motor, patterns for allow-listed people |
| Battery | About 200 to 250 mAh, around a week (estimate) |
| Charging | Two pins on the lower case edge, flat back |
| Connection | Bluetooth LE to the Humanly Phone concept or any phone |
| Straps | Standard quick-release, in leather, fabric or a titanium link |
| Software | Three screens, no apps, no store |
What we gave up
A concept is only useful if it is honest about its weak points. Here are the ones we see.
Battery volume. Energy lives in volume, and a 5 mm case leaves very little of it. A week is only possible because the feature list is tiny. Add an always-on display, GPS or a speaker and the battery life falls to a day or two, or the case gets thicker. There is no clever trick that avoids this.
Health sensors. We dropped them. No optical heart rate, no blood oxygen, no skin temperature, no ECG. Those sensors need a window on the back, usually a raised dome to press against the skin, and they are some of the most useful things a modern watch does. For many people, especially anyone who relies on a watch for health tracking, that alone rules this concept out. We would rather say so plainly than add one weak sensor and pretend.
Water resistance. A thin case with a sapphire front, a button and two charging pins has several seams to seal. Splash and rain resistance seems realistic. Swimming, without a thicker case or more gasket, we are not confident about. The pins would need to be sealed in the case and resistant to sweat corrosion, which is a known problem with exposed contacts.
Comfort and strength. A flat back sits nicely on a wrist. A 5 mm titanium shell is stiff, but a very thin case is always more vulnerable to a hard knock at the corners than a thick one.
Cost. Machined titanium, sapphire and a custom thin cell are expensive parts. A watch that does three things at the price of one that does thirty is a hard sell, and we do not have an answer to that yet.
If you wear a thin mechanical watch and gave up on smartwatches because of their size, or you think a watch without health sensors is pointless, we would like to hear from you on the contact page. The allow-list tap is the one feature we would keep if we had to cut everything else, and we are curious whether that is true for anyone besides us.