Buzz — But What Does It Really Mean

We’ve all been there. Walking through the airport, pushing a luggage cart, and your watch buzzes — another 100 steps closer to your daily goal. It feels good. Almost too good.

But here’s the question nobody asks: did you actually earn those steps?

I spent a month testing three different smart watches while manually tallying my actual steps with a clicker counter. The results made me realize that step counting isn’t measurement. It’s interpretation.

The Pendulum Inside Your Wrist

At its core, step counting is glorified pendulum detection.

Your watch contains an accelerometer — a tiny chip that measures acceleration forces in three directions. Every time you move your arm, the chip records a wave of data: how fast, which direction, and for how long.

But here’s the catch: walking isn’t the only thing that makes your arm swing. Brushing your teeth, typing furiously, or even gesturing while talking all create similar acceleration patterns.

The algorithm’s job is to distinguish between “this is walking” and “this is just random arm movement.”

Frequency, Amplitude, and the Art of Filtering

Smart watch engineers use two main filters to separate steps from noise.

Frequency filtering. Walking has a characteristic rhythm — typically between 1.5 and 2.5 steps per second. Arm flaps outside this range get discarded. That’s why drumming on your desk rarely counts as steps, no matter how vigorously you channel your inner rockstar.

Amplitude thresholding. Real steps produce sustained, moderate acceleration. A sudden, sharp movement — like swatting a mosquito — creates a high-amplitude spike that the algorithm recognizes as noise, not locomotion.

Still, these filters aren’t perfect. Push a shopping cart with stationary arms? Zero steps. Push a stroller with one hand and swing your free arm? Congratulations, you just walked an extra mile.

Why Different Watches Give Different Numbers

I wore an Apple Watch, a Garmin, and a Xiaomi band simultaneously for a week. Same wrist, same walks. The step counts differed by up to 12%.

This isn’t manufacturing defect. It’s algorithmic philosophy.

Some brands prioritize sensitivity — they’d rather overcount than miss a step. Others prioritize specificity — they accept missing some real steps in exchange for not counting false ones.

Neither is wrong. They’re just optimized for different user expectations.

Wrist-based step counting has a fundamental blind spot.

Your arm swings after your foot lands. There’s a slight delay between ground contact and arm motion. The watch isn’t measuring your steps — it’s measuring the aftermath of your steps.

This is why waist-worn pedometers were technically more accurate. They sat closer to your center of mass, where walking actually happens. But we traded accuracy for convenience, and honestly, most of us don’t want to clip a device to our belt loops anymore.

Calories — The Step Count’s Unreliable Cousin

Once your watch decides you’ve taken steps, it multiplies that number by your weight, height, age, and estimated stride length to calculate calories burned.

This is where things get fuzzy.

Calorie estimation formulas were developed in laboratories using metabolic chambers and face masks — not wrist motion. Your watch doesn’t know your muscle mass, your metabolic efficiency, or whether you walked uphill or on flat ground unless it has built-in GPS.

Take those calorie numbers as rough suggestions, not scientific facts.

What Actually Matters

The exact number doesn’t matter.

What matters is consistency.

If your watch says you walked 6,000 steps today and 7,500 steps yesterday, the absolute numbers might be inaccurate, but the trend is real. You moved more yesterday. That’s useful information.

Step counting algorithms aren’t truth-tellers. They’re translators — imperfect ones at that. But they translate the messy physics of arm swinging into a language we understand: progress.