Apple Watch Ultra 4 rumors just got concrete: on April 3, per 9to5Mac’s code teardown, someone dug through watchOS code and found “AppleMesa.”

If you can wait until September, wait — the Ultra 4 is the generational upgrade the Ultra 3 wasn’t.

That codename — buried in firmware alongside references to doubled sensor component counts and exterior design changes — is the most concrete evidence we’ve gotten about the Apple Watch Ultra 4. Not a supply chain whisper. Not an analyst guess. Actual code, sitting in Apple’s own software, confirming Touch ID integration and a significant hardware overhaul coming this fall.

And now anyone staring at the $799 Ultra 3 on Apple’s website is wondering if they’re about to buy last year’s model five months before the replacement ships.

I’ve been covering the Apple Watch ecosystem on this site for a while: watchOS AI coaching features, Strava navigation on Apple Watch, Project Mulberry’s health ambitions. But always the software side. This is our first look at the Ultra hardware itself, and the leaks are solid enough to have the wait-or-buy conversation.

Quick Verdict

Factor	Ultra 3 (Buy Now)	Ultra 4 (Wait)
Availability	Shipping today	Expected September 2026
Price	$799	Likely $799-$899
Touch ID	No	Confirmed in code (AppleMesa)
Health Sensors	Same core hardware as Ultra 2	Doubled sensor component count
Design	Titanium, same since Ultra 1	Code references exterior changes
Battery	36-60 hours	Power efficiency gains expected
Software	watchOS 12 this fall	watchOS 12 this fall

Short answer: If you’re training for something right now and need a watch on your wrist this month, buy the Ultra 3. It’s a great watch. If you can wait until September and your current watch still works, wait. The sensor leap alone could be worth five months of patience.

What the Code Actually Says

Here’s what’s actually confirmed vs. what people are guessing.

Confirmed in watchOS code (April 3 leak)

1. “AppleMesa” codename tied to Touch ID functionality. References in authentication frameworks point to biometric scanning integrated into a physical button (side button, Digital Crown, or Action button)
2. Sensor component count roughly doubled compared to Ultra 3 internals. This doesn’t mean twice as many visible sensors on the caseback, but it points to a big jump in sensor hardware
3. Exterior design changes referenced in code alongside new case dimensions or materials
4. Power efficiency improvements indicated by updated thermal and battery management code paths

Not confirmed (reasonable expectations)

• Specific new health metrics (blood glucose, blood pressure, advanced SpO2)
• Price point
• Exact release date beyond the standard September window
• What Touch ID would actually unlock (Apple Pay on wrist, app authentication, unlocking paired iPhone)

The distinction matters. We know the Ultra 4 is getting Touch ID and better sensors. We don’t know exactly which health features those sensors will enable at launch. Apple has a long history of shipping sensor hardware and activating features later via software updates. The Apple Watch had the hardware for crash detection and temperature sensing before those features went live.

What Doubled Sensors Could Mean for Athletes

This is the part that got my attention.

The Ultra 3 (and the Ultra 2 before it) uses essentially the same optical heart rate sensor array that’s been in the Apple Watch since Series 6. It works fine for most training. Heart rate during steady-state cardio is accurate within a few BPM of a chest strap. But wrist-based optical sensors have known limitations: interval work, cold weather, dark skin tones, certain wrist positions during weightlifting. More sensor components typically means more LED wavelengths and photodiodes, which translates to better signal quality in harder conditions.

Doubled sensor density could enable:

• More accurate HRV readings. Currently, the Apple Watch’s HRV measurements are decent for trends but noisy compared to chest straps or dedicated devices like WHOOP. Better optical hardware could close that gap.
• Improved SpO2 reliability. Blood oxygen on the current Ultra is inconsistent enough that I rarely trust a single reading. More sensor points means more data averaging, which means less noise.
• New biometric capabilities. Blood pressure estimation (Samsung is already doing this with Galaxy Watch, though setup is painful), continuous glucose indication, hydration monitoring. None of these are confirmed for Ultra 4, but doubled sensor hardware makes them physically possible.
• Better accuracy during high-intensity movement. The optical sensor’s worst moments are during explosive movements: box jumps, burpees, heavy cleans. More LEDs and photodiodes reading from slightly different angles could reduce motion artifact.

For the average runner doing zone 2 training, the current Ultra 3 sensors are fine. The upgrade matters most for people pushing the edges of what wrist-based monitoring can do: CrossFit athletes, obstacle course racers, cold-weather endurance sports, anyone who’s noticed their HR readings get flaky when things get intense.

Touch ID: Why It Matters on a Watch

My first reaction to “Touch ID on Apple Watch” was mild skepticism. I don’t need a fingerprint sensor to start a run. But think about it for 30 seconds and the use cases stack up.

Apple Pay without a passcode dance. Currently, you authenticate Apple Pay on Apple Watch by entering a PIN after you put the watch on. If you take it off and put it back on, you re-enter the PIN. Touch ID would let you authenticate with a finger touch on the side button or crown. Small convenience that adds up over a day.

App authentication. Medical apps, banking apps, anything that currently requires you to pull out your phone to authenticate could use Touch ID on the watch instead. For athletes who leave their phone behind during training (which Strava’s new navigation makes more viable), this removes a friction point.

Security without annoyance. The passcode on Apple Watch is four digits on a tiny screen while your hands are sweaty. It’s bad. Everyone who uses Apple Watch for workouts knows it’s bad. Touch ID on a physical button you’re already pressing solves this without adding steps.

The “AppleMesa” code references point to the biometric sensor being in a physical button: side button, crown, or Action button. My bet is the Action button. It’s the most natural place to press a thumb during authentication, and it’s the button that gets the least constant use during workouts. But that’s speculation.

The Ultra 3 Problem

Here’s the uncomfortable truth about the Apple Watch Ultra 3: it was a disappointment.

Launched September 2025 at $799, the Ultra 3 used essentially the same core hardware as the Ultra 2. Same sensor array. Same display. Same titanium case. The upgrades were the S10 chip (faster processing, better battery management) and a slightly wider band of cellular connectivity. That’s it.

People who owned an Ultra 2 had no reason to upgrade. People who owned an Ultra 1 had marginal reasons. The Ultra 3 was a great watch. The Ultra 2 was a great watch, and the Ultra 3 was basically the same thing with a faster processor.

At $799, “same hardware, faster chip” is a tough pitch. And now, six months after launch, code leaks are confirming that the Ultra 4 is the generational leap the Ultra 3 should have been. Touch ID. Doubled sensors. Design changes. Power efficiency gains. That’s a real upgrade list. The kind that makes $799 feel justified.

Which makes the Ultra 3 the worst time to buy, right?

Not necessarily.

The Case for Buying Ultra 3 Now

I know. Everything I just wrote screams “wait.” But there are real scenarios where buying today makes sense.

You’re training for a fall event. Marathon in October? Ironman? A big race that has you deep in a training block right now? You need a watch now, not in September. Five months of training data, route navigation, and daily health metrics has actual value. Waiting means training with whatever you have now (or nothing) and switching devices mid-cycle. That disrupts baseline data and means your watch doesn’t understand your fitness history when race day arrives.

Your current watch is dying. If your Series 6 battery lasts four hours or your Garmin screen cracked last week, you’re not in a position to wait. Buy what’s available.

You’ll get a discount. Ultra 3 prices will drop when Ultra 4 launches. Refurbished Ultra 3 units will flood the market in September and October. But you can sometimes find deals now too: carrier promotions, trade-in credits, retailer bundles. At $650-700, the Ultra 3 is a strong value.

You don’t care about Touch ID. If the passcode doesn’t bother you and you’re not doing Apple Pay from your wrist regularly, the Ultra 4’s headline feature isn’t relevant. The sensor improvements might matter, but if your current Ultra’s HR tracking meets your needs, “better sensors” is incremental rather than essential.

The Ultra 4 might cost more. The Ultra 3 launched at $799. The Ultra 4 could hold that price. Or Apple could bump it to $849 or $899 given the new hardware. Touch ID components, doubled sensor arrays, and design changes aren’t free.

The Case for Waiting

Five months isn’t that long. September is 22 weeks away. If your current watch works, that’s not an eternity. And watchOS 12 (whatever it brings) will ship to both Ultra 3 and Ultra 4.

The sensor leap matters. Going from incremental sensor improvements to doubled component count is unusual for Apple. They typically make small refinements year over year. A big jump suggests either new health features at launch or the hardware foundation for features coming in watchOS 13 and beyond. Either way, you want the newer sensor platform.

Touch ID will be standard going forward. If Apple puts Touch ID in the Ultra 4, every future Ultra will have it. The Ultra 3 becomes the last generation without it. That affects resale value and long-term usability.

The Ultra 3 was a skip year. Buy the leap, not the placeholder. Ultra 1 was the leap. Ultra 2 was the refinement. Ultra 3 was treading water. Ultra 4 looks like the next leap. The pattern says buy.

Who Should Buy the Ultra 3 Right Now

You’re mid-training-cycle for a goal event before November. You need a watch today, your current one isn’t cutting it, and five months of training data on a reliable platform is worth more than hypothetical future features.

You want the Apple Watch Ultra experience at the lowest price it’ll ever be. Wait for Ultra 4 to launch, then buy the Ultra 3 at a discount. That’s the smart play if you want the form factor without the premium of new-model pricing.

Who Should Wait for the Apple Watch Ultra 4

You’re not in an urgent training window. Your current watch (Apple Watch, Garmin, whatever) still works. You can afford patience.

You care about health tracking accuracy enough that doubled sensor hardware actually matters to your training decisions. You rely on HRV, blood oxygen, or heart rate data during high-intensity training and you’ve noticed the current sensors falling short.

You want the most future-proof Apple Watch hardware available. The Ultra 4’s sensor platform and Touch ID will be the baseline for years. The Ultra 3’s won’t.

What About Garmin and WHOOP Instead?

Fair question. If you’re on the fence about Ultra hardware, maybe the answer isn’t either Ultra.

A Garmin Fenix 8 or Forerunner 970 gives you better battery life, better navigation, deeper training load analysis, and costs about the same. You lose the Apple ecosystem integration (iMessage on your wrist, Apple Pay, smooth iPhone pairing), but for pure training, Garmin is still ahead of any Apple Watch. The watchOS AI coaching features are closing the gap on the software side, but hardware-wise, Garmin’s multi-day battery and built-in maps remain unmatched.

And if recovery tracking is your priority over smartwatch features, a WHOOP 5.0 or Garmin CIRQA gives you more granular recovery data than any Apple Watch, Ultra or not. Different tool for a different job.

My Honest Take

If someone handed me $799 today and said “buy a watch,” I’d wait until September.

The Ultra 3 is good. I’ve tested apps on it extensively, tracked runs with it, used it for daily health monitoring. As a smartwatch for athletes, it’s the best Apple has shipped. But “the same as Ultra 2 with a faster chip” is exactly the kind of product that gets superseded hard when the real upgrade comes.

And the Ultra 4 looks like the real upgrade. Touch ID isn’t a gimmick — it solves a genuine annoyance (that tiny passcode screen with wet fingers). Doubled sensors aren’t marketing. That’s a hardware investment that enables either immediate or future health capabilities. Design changes suggest Apple knows the Ultra needed more than a chip swap this time.

September is 22 weeks away. Unless you’re in a training block that can’t wait, those weeks will pass. And you’ll either buy the Ultra 4 at launch or buy the Ultra 3 at a discount once the new model makes it last-gen.

Either way, buying the Ultra 3 at full price in April 2026 is the worst of the three options.

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Based on watchOS code analysis published April 3, 2026 revealing “AppleMesa” Touch ID codename and doubled sensor component counts for Apple Watch Ultra 4. Ultra 3 pricing reflects current US Apple Store rates. Expected Ultra 4 availability September 2026 based on Apple’s standard Watch release cadence. No hands-on testing of Ultra 4 hardware. All Ultra 4 details are from code analysis, not personal use.