There are dozens of ways to count your steps, from mechanical pedometers to computerized fitness trackers.

Nearly all of them work well enough to monitor your daily activity, says Catrine Tudor-Locke, director of the Walking Behavior Research Laboratory at the Pennington Biomedical Research Center.

“They measure differently,” Tudor-Locke says. “You yourself can go out and get three or four different devices, and you may get some kind of general agreement between them, but you will definitely get differences between them. It’s not like a ruler. … And there is no industry standard.”

Pedometers that only measure steps have been around for decades, while computerized activity trackers — made by Fitbit, Jawbone and other companies — that count steps and measure the quality of your sleep have become the most popular fitness gadgets on the market in recent years.

Some use mechanical lever arms to register steps taken, while others use accelerometers or electronic circuits. The electronic ones each use different algorithms to reach their measurements. Tudor-Locke does not recommend a particular brand.

“All of them should be able to accurately pick up walking if you went for a walk — a purposeful, forceful walk,” she says. “They all should be able to get that. But all of them will be slightly different on the slow, shuffling steps and the jumping activities.”

Step counters are not meant to precisely count every step. They are meant to give you an idea of your daily activity level.

“It’s meant to increase awareness,” Tudor-Locke says. “It’s meant to help you with your behavior change.”

To ensure your step counter works well, Tudor-Locke recommends the following tests:

GO FOR A SHORT WALK. Wearing your step counting device, walk 20 steps, counting them aloud. The device should read 19, 20 or 21 steps.

“That is within an acceptable margin of error,” Tudor-Locke says. “If it says 13 or 43, you may want to move it around on your body a bit and see if it is a placement issue and try it again. If it continues to be out of whack, then it is not the one for you.”

TAKE A DRIVE. Put on your step counter, get in your car and take a drive.

If your device only counts a few steps, it should be working well.

“If it says 122 or 1,000, then it’s counting steps while you’re sitting in a car,” Tudor-Locke says. “On some devices, their measurement mechanism, they make it very sensitive to low-force acceleration. It’s trying to give you benefit for all those shuffle steps. The trade-off is it’s going to give you false steps when you are in a car.”