A pedometer, or step-counter, is a device, usually portable and electronic or electromechanical, that counts each step a person takes by detecting the motion of the person's hands or hips. Because the distance of each person's step varies, an informal calibration, performed by the user, is required if presentation of the distance covered in a unit of length (such as in kilometers or miles) is desired, though there are now pedometers that use electronics and software to automatically determine how a person's step varies. Distance traveled (by walking or any other means) can be measured directly by a GPS receiver.

Used originally by sports and physical fitness enthusiasts, pedometers are now becoming popular as an everyday exercise counter and motivator. Often worn on the belt and kept on all day, it can record how many steps the wearer has walked that day, and thus the kilometers or miles (distance = number of steps × step length). Some pedometers will also erroneously record movements other than walking, such as bending to tie one's shoes, or road bumps incurred while riding a vehicle, though the most advanced devices record fewer of these 'false steps'. Step counters can give encouragement to compete with oneself in getting fit and losing weight. A total of 10,000 steps per day, equivalent to 8 kilometres (5.0 mi), is recommended by some to be the benchmark for an active lifestyle, although this point is debated among experts. Thirty minutes of moderate walking are equivalent to 3,000-4,000 steps as determined by a pedometer. Step counters are being integrated into an increasing number of portable consumer electronic devices such as music players, smartphones, mobile phones and watches (called activity trackers)