Apple Watch Aura Strap measures body fat and hydration

Bioimpedance analysis?

The Aura Strap for Apple Watch uses bioimpedance technology to measure body composition broken down into four components: fat, muscle mass, minerals, and body water.

"Bioimpedance analysis is a noninvasive, low cost and a commonly used approach for body composition measurements and assessment of clinical condition." - The Theory and Fundamentals of Bioimpedance Analysis in Clinical Status Monitoring and Diagnosis of Diseases

Basically, a small electric is transmitted through your body and then the resulting electrical resistance measured is used to determine how much fat mass, fat-free mass, water, muscle, and mineral the body is made of.

The use of bioimpendance to determine body composition is not new. It has been used in high tech smart scales for quite some time.

However, having the technology on your wrist and connected to the Apple Watch enables a more convenient and regular measurement of your body composition, which in turns allows you to see the trend in your body composition changes.

Take away the guess work

With the Aura Strap connected to your Apple Watch, you can get more out of your fitness activities as you can now see how it affects your body.

Using the Aura App you can set goals like gain a certain amount of muscle or lose a certain amount of fat. You can then follow a training philosophy or join a training program and track your body composition on a daily basis to see if it works for you. 

The Aura Strap can help you find out what works for your unique biology so you can reach your fitness goals much quicker.


The Aura Strap can also tell you when you need to drink water based on your activity data and your body hydration levels.

Hydration can be tracked daily, hourly, or more frequently depending on your needs.

No Apple Watch?

At the time of writing, you can get the Aura Strap for $99 on pre-order. For that price you get the Aura Strap, a coin battery (CR1620), and a screwdriver for battery replacement, which you'll need to do in about 6 months.

You'll need an Apple Watch for the device to work. If you don't have an Apple Watch, consider getting the Aura Band - a similar device but it can also measure your heart rate and track activities including your workouts and sleep.

The Aura Band works with Apple Healthkit, Google Fit, Strava, and MyFitness Pal.


  • Add functionality to your Apple Watch
  • Can help you determine which workouts are best for you and your goals
  • Can be used to regularly check your body composition and spot trends


  • Pre-order only (at the time of writing)
  • Not the best looking strap
  • Accuracy unknown


The Aura Strap adds more functionality to your Apple Watch that can be quite useful to make the most out of your workouts. The accuracy of such a device is yet to be known but it doesn't take away its usefulness especially when you use it to spot trends.

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