That's what I set out to discover when I strapped my Jawbone UP, FitBit Force, and Basis B1 Band to my left wrist, and an Omron Walking Style pedometer to my right hip.
I attached all four fitness trackers from the moment I woke up until the moment I went to sleep for 8 days. I went about my daily activities, noting down the step count that each device at recorded at the end of each day.
While I had my own impressions of the general trend for each of these fitness trackers, the chart provides and interesting comparison of how these fitness trackers really measure up in the steps department.
Fitness Tracker Step Accuracy Comparison
Thoughts on Accuracy
For most people's use cases, it's not such a great harm if some arm motions do get categorized as steps. Calories were burned making arm motions intense enough to be picked up by the fitness tracker in the first place, and having them interpreted as steps at least gives some credit (in terms of active time and calories) for that upper body physical activity.
In a similar test with the same set of fitness trackers, I manually counted out exactly 1000 steps while on a walk, letting each of the trackers do their best to count the same steps. This helps provide a benchmark to measure accuracy against. I'll post that comparison to the blog soon, and will link to it from here!
If you're curious to read more about these fitness trackers, I have reviews of the Jawbone UP, Basis B1, Basis Peak, and FitBit products.
Notes on Human Error
Another note: After my morning workout, which was heavy on the jumping jacks and arm exercises with weights, the wrist-based trackers seemed to have counted an extra 500 to 1000 steps more than the Omron Walking Style pedometer.