Smart watch metrics - how accurate are they?
May 31, 2023
I was curious about how accurate my apple watch is, so I did some digging and found this video: https://www.youtube.com/watch?v=fDj2kYIF-sE
In this, they try out four devices: Apple watch, Mi Band, Fitbit, and a phone in hand.
It's worth watching in full, but here's a summary:
- In general Apple watch is close. Phone does the best
- If your hand is fully steady, Apple watch counts 0 (in the video he's carrying a glass of water). Fitbit and the phone do better.
- Apple watch does better when you are walking weirdly too. Fitbit/mi band and phone all overcount in these cases.
- Fitbit overcounts a lot. For eg, in this video, it counts steps even when driving.
- Heart rate
- Benchmarked against an electric measure strapped to the chest.
- While running
- All of them mostly do good, except in extreme cases (sudden change in running pace for example).
- In the case of a sudden increase, Apple watch comes the closest to real heart rate.
- Throughout the day
- Apple watch's frequency of recording is 4 minutes, compared to Fitbit's 8 seconds & Mi Band's one minute. This means that Apple watch misses a lot of cases.
- Mi band is the least accurate.
- Sleep tracking
- All watches work well in this case, as conditions are ideal. Avg error is 1.8 bpm for Apple & Fitbit, 3.4 for Mi band