The Number Your Apple Watch Calculates But Never Shows You

Your Apple Watch knows something about your training that it never tells you.

Every single workout you log, the watch calculates a value called MET. It records it. Stores it. Sends it to the Health app. And then it just… sits there. No weekly total. No trend line. No comparison to any standard. The single most important number in exercise science, and Apple treats it like metadata.

Meanwhile, the World Health Organisation has been using MET minutes as the gold standard for measuring physical activity for over a decade. Every major public health guideline on the planet references them. Your watch has all the raw data needed to calculate your weekly MET minutes total. It simply never does.

What are MET minutes (and why should you care)?

MET stands for Metabolic Equivalent of Task. One MET is the energy you burn sitting completely still. It is your baseline, your metabolic idle speed. When you walk briskly, you hit about 3.5 METs. A hard cycling session might put you at 8 METs. Flat out sprinting pushes you north of 12.

MET minutes multiply the intensity by the duration. A 30 minute run at 8 METs gives you 240 MET minutes. A 45 minute yoga session at 2.5 METs gives you 112.5. The beauty of this system is that it lets you compare completely different activities on the same scale. Rowing versus swimming versus a CrossFit class versus a long walk with the dog. All reduced to one number that accounts for both how hard you worked and how long you worked for.

The WHO recommends 150 to 300 MET minutes of moderate intensity activity per week, or 75 to 150 MET minutes of vigorous activity. In practical terms, a combination of both is how most people train. If you are a serious athlete doing five or six sessions a week, you are almost certainly blowing past these minimums. But by how much? And is your volume consistent week to week, or does it swing wildly?

You have no idea. Because nobody shows you the total.

Your Apple Watch already does the hard part

Here is what makes this genuinely frustrating. Open the Health app on your iPhone. Tap into any workout. Scroll down to the details. You will find a field called “Average METs” or “MET value” sitting right there in the data. Apple Watch is calculating this for every single session using your heart rate, weight, age, and the type of activity you logged.

The hard part is the calculation. Apple already does it. The easy part is multiplying that number by the duration and adding up the week. Apple never does that.

Think about what the watch does show you. Three coloured rings. Move, Exercise, Stand. These are fine for getting sedentary people off the couch. But if you train seriously, you closed those rings before breakfast. They tell you nothing about training load, intensity distribution, or whether your week was harder or easier than last week in any meaningful way.

Active calories are similarly limited. They don’t account for intensity in a standardised way. Two people burning 500 calories had wildly different sessions depending on their weight, fitness level, and what they were doing. MET minutes normalise all of that.

The gap between consumer fitness and sports science

This is where consumer fitness tracking and actual sports science diverge. Research papers don’t measure physical activity in calories or ring closures. They use MET minutes. Dose response studies on exercise and mortality use MET minutes. The studies that tell you “X amount of exercise reduces cardiovascular risk by Y percent” are quantifying X in MET minutes.

When your doctor asks if you’re getting enough exercise, the clinical answer is measured in MET minutes. When the WHO publishes guidelines for 194 member states, they use MET minutes. This is not an obscure academic metric. It is the global standard.

And yet no major consumer wearable surfaces it as a weekly dashboard number.

Garmin gives you Training Load and Body Battery. Apple gives you rings and trends. Whoop gives you strain scores. All of these are proprietary interpretations of your data, built on internal algorithms that you cannot compare across platforms. MET minutes are none of those things. They are an open, standardised, universally understood unit. That is precisely why they matter.

Why weekly MET minutes change how you train

Tracking weekly MET minutes does something that no other consumer fitness metric currently does. It gives you a single number that captures your total training volume in a way that is comparable across time, across activities, and across people.

Say you normally log around 1,800 MET minutes per week. Then you travel for work, miss two sessions, and only hit 900. That is a 50% drop in volume. You can see it. You can plan around it. You can decide whether to ramp back up gradually or jump straight back in.

Or say you’re building towards an event. Hyrox in July, a half marathon in August. You can watch your weekly MET minutes climb from 1,200 to 1,600 to 2,000 over a training block and know that you’re progressively overloading in a measurable way. Not guessing. Not vibing. Measuring.

Compare that to checking whether you closed your rings. The rings are binary. You either did or you didn’t. There is no gradient, no volume tracking, no periodisation insight. They were designed to motivate beginners, and they do that job well. But they were never built for athletes who need to manage training load across a season.

The problem with proprietary scores

Whoop’s strain score is a number from 0 to 21. What does a 14.2 mean in universal terms? Nothing, unless you’re inside the Whoop ecosystem. Garmin’s Training Load uses a different scale entirely. Apple’s Exercise ring counts minutes above a heart rate threshold but doesn’t weight for intensity.

None of these translate. Switch platforms and your history is meaningless. Compare notes with a training partner on a different device and you’re speaking different languages.

MET minutes solve this. A MET minute is a MET minute regardless of whether it was recorded on an Apple Watch, a Garmin, a Polar, or a chest strap connected to a phone. The unit is defined by physiology, not by a product team in Cupertino or Oulu.

This is not a knock on those companies. Their proprietary metrics serve specific purposes and some of them are genuinely useful. But the fitness industry is missing a lingua franca for training volume. MET minutes already exist as exactly that. The wearables just refuse to surface them.

What P247 is building

We think this is a gap worth closing.

P247 is building MET minutes tracking into the platform. Not as a novelty feature, but as a core metric. Weekly totals. Trend lines over months. Breakdowns by activity type. Context against WHO guidelines so you can see where your volume sits relative to evidence based recommendations.

Your Apple Watch (or Garmin, or whatever you wear) already captures the data. P247 will pull it together, aggregate it, and show you the number that actually matters.

Because the point of wearing a sensor on your wrist all day is not to collect data. It is to understand what the data means. And right now, for one of the most important metrics in exercise science, the understanding part is completely missing.

The bottom line

MET minutes are not new. They are not experimental. They are the established global standard for quantifying physical activity, used by every major health organisation on the planet. Your wearable calculates the components every time you work out. The final step of adding them up and showing you the total is trivially simple.

Nobody does it.

That is about to change.