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How do Smartwatch Sensors actually work? Find out.

How do Smartwatch Sensors actually work? Find out.

Smartwatches have been in the spotlight for their extensive health and fitness benefits for a long time running, and countless studies prove that they do make a difference! They have changed the dynamic of at-home healthcare and have allowed individuals to experiment with fitness, all with the help of advanced secret algorithms that allow them to be more productive, efficient, and connected.

You might have noticed the number of sensors and lights on the back of your smartwatch. But how do they really work, and can they benefit you? Let’s find out.

1. SpO2

The level of oxygen in your blood can be determined by its color. Your smart tracker examines this using reflectance-based oximetry which basically measures the relative refraction of red and infrared lights from your blood, via the wrist, and accounts for its variation with your heartbeats. The darker the blood, the lesser the oxygen present in it.

This can be used as a preventative measure for anyone suffering from shortness of breath on the regular. However, this doesn’t cover for your regular doctor's visits!

2. HR and Stress

Trackers nowadays use a technology called photoplethysmography, or PPG, to measure your heart rate. Blood is red because it reflects red light and absorbs green light, so when your heart beats, there’s more blood flow in your wrist, and more green light absorption. Between heart beats, there’s less absorption of green light.

By flashing its LED lights hundreds of times per second, a smartwatch can calculate the number of times the heart beats each minute — your heart rate. Similarly, it accounts for your stress by measuring the variation of time between beats.

3. Calories

Tired of manually logging your daily calories? Let the watch do your dirty work. A smartwatch has proven to keep eating habits in-check by giving constant health reminders from the smart health app and logging daily calorie intakes, so you know when to stop munching.

Calories burned are measures based on two things: The measurements taken with the watch’s internal accelerometer tracking your activity levels, and your basal metabolic rate, which is determined by algorithms and the data you provide.

So, set your calorie goals for the week and you’ll be good to go!

4. Sleep

Another hallmark feature that smartwatches provide is their ability to tell you how long you slept — and even how well you slept. This often bags the question, “how does the watch know I’m asleep?”

It’s the wrist trackers monitoring your littlest movements to determine your state of consciousness. While you sleep, your heart rate fluctuates as you go through the light, deep and REM stages, and the watch uses this data to map your sleep cycles and give you customized sleep insights.

You can use this feedback to make the required changes to your routine as per what works, and what doesn’t.

5. Fitness

Smartwatches are booming among athletes and fitness enthusiasts because of their dynamic real-time fitness tracking that’s not just confined to workouts, but also a variety of sports, thanks to their Multisport function.

They record your pace, intensity, and distance travelled, so you’re better informed and avoid mistaking poor technique for low stamina. Most watches have a three-axis accelerometer and gyroscope that sense and interpret your movements throughout the day to give you useful performance feedback.

Additionally, they store all your data so you can see how far you've come from your last checkpoint.


Your smartwatch can be anything you make it to be – a tracker, motivator, trainer. All you must do is make it work for you and take all the health and fitness advantages that come with it.

Looking for a banger Smartwatch to track your everyday progress? Check out our Smart Collections.

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