system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are fitness trackers accurate?

How do Apple watches, FitBits, etc. accurate? Are they truly precise?
gpt
Short answer? They're not. They use algorithms based on things like movement (steps) to estimate calorie burn to varying degrees of success.

*However*, a good fitness tracker can still be worthwhile. That's because a good tracker is usually *consistent*. That means that once you get it dialed in, you can use it fairly effectively for things like weight loss.