Flextime (also spelled flexitime (BE) or flex-time) is a flexible hours schedule that allows workers to alter their workday and decide/adjust their start and finish times. In contrast to traditional work arrangements that require employees to work a standard 9 a.m. to 5 p.m. day, flextime typically involves a "core" period of the day during which employees are required to be at work (e.g., between 11 a.m. and 3 p.m.), and a "bandwidth" period within which all required hours must be worked (e.g., between 5:30 a.m. and 7:30 p.m.). The working day outside of the "core" period is "flexible time", in which employees can choose when they work, subject to achieving total daily, weekly or monthly hours within the "bandwidth" period set by employers, and subject to the necessary work being done. The total working time required of employees on flextime schedules is the same as that required under traditional work schedules.

A flextime policy allows staff to determine when they will work, while a flexplace policy allows staff to determine where they will work. Advantages include allowing employees to coordinate their work hours with public transport schedules, with the schedules of their children, and with daily traffic patterns to avoid high congestion times such as rush hour. Some claim that flexible working will change the nature of the way we work. The idea of flextime was invented by Christel Kammerer and Wilhelm Haller. The World Health Organization and the International Labour Organization estimate that over 745,000 people die from ischemic heart disease or stroke annually worldwide because they have worked 55 hours or more per week, making long working hours the occupational hazard with the largest disease burden.