These are the three things to look out for when counting calories on your fitness tracker.
First off, make sure your information is up to date.
Fitness trackers like the Apple Watch and Fitbit use stats like gender, height, and weight to determine calorie count.
They also factor in heart rate into the equation, especially during a workout to figure out how hard you're working.
So it's important to get a good read.
To do this, make sure the censor is as close to your skin as possible and will stay in place, even if you're swinging your arm around.
This means getting the band as tight as possible without pinching your skin.
And the censor should always sit on top of your wrist.
The last thing to take into account is distance traveled, which is determined by your stride and pace along with GPS, if your tracker has this feature.
Which is why most trackers will have you calibrate them during setup.
To do this you'll want to walk or run in a flat area with good GPS signal for about 10 to 20 minutes to establish a baseline for this type of information.
And you may want to bring your phone along with you for the first one.
In San Francisco, I'm Vanessa Hand Orellana.
CNET.com for CBS News.