Federal law does not impose a universal cap on the number of hours an adult can legally work in a row. The maximum allowable hours depend entirely on the worker’s age, the industry, the specific job function, and the state where they are employed. For most of the workforce, the law focuses on how employers must compensate for extended hours, rather than how many hours they can demand. Restrictions on continuous work become more definite when public safety is a factor or when the employee is a minor.
General Federal Guidelines on Working Hours
Federal law, established by the Fair Labor Standards Act (FLSA), does not set an upper limit on the number of hours an adult employee (aged 16 or older) can be required to work in a single day or workweek. An employer can legally schedule an adult for shifts of 12 hours, 16 hours, or longer, and for any number of consecutive days. The law requires that non-exempt employees receive overtime pay at a rate of one and one-half times their regular rate for all hours worked over 40 in a single workweek. This financial penalty serves as the main federal deterrent against excessively long work schedules. The absence of a daily or weekly hours cap means that, without state-specific or industry-specific rules, an employer has significant discretion over scheduling.
Mandatory Break and Rest Periods
Federal law does not mandate meal or rest breaks for adult employees during a shift. The FLSA only dictates how breaks must be treated when an employer chooses to provide them. Short rest periods, typically lasting 5 to 20 minutes, must be counted as compensable work time and cannot be unpaid. Meal periods are not required to be paid if they are 30 minutes or longer and the employee is completely relieved of all duties. Many states enforce stricter standards, often requiring a 30-minute unpaid meal break for shifts exceeding five or six hours, or mandating paid rest breaks, such as a 10-minute break for every four hours worked.
State-Specific Regulations on Maximum Hours
Many states have introduced their own regulations concerning the amount of rest required between shifts. While most states do not impose a hard limit on the number of hours an adult can work in a day or week, some laws effectively cap hours by mandating a minimum rest period between shifts. These “right to rest” laws often require 8 to 10 consecutive hours off between scheduled work periods. State laws also frequently target specific, high-stress occupations, such as healthcare, to prevent fatigue-related errors. Several states restrict mandatory overtime for nurses, particularly in hospitals, often capping shifts at 12 consecutive hours after they have completed a scheduled shift. This patchwork of state rules means that an employee’s maximum continuous working hours can vary significantly depending on their geographic location.
Federal Limits for Regulated Industries
The most definitive federal limits on working hours are found in industries where employee fatigue poses a direct threat to public safety. These regulations are known as Hours-of-Service (HOS) rules and are enforced by various federal agencies.
Transportation and Commercial Driving
The Federal Motor Carrier Safety Administration (FMCSA) imposes strict HOS rules on commercial truck and bus drivers. A property-carrying commercial driver is limited to a maximum of 11 hours of driving time within a 14-hour duty window, after which they must take a mandatory 10 consecutive hours off-duty. Furthermore, drivers are limited to working a maximum of 60 on-duty hours over seven consecutive days or 70 hours over eight consecutive days, which can only be reset by taking a 34-hour rest period.
Aviation
Pilots and flight crew operating under Federal Aviation Administration (FAA) regulations also face strict flight time and rest requirements. For most commercial operations, flight time is limited to a maximum of 8 hours in any 24-hour period for a single-pilot crew. Crew members must be scheduled for a minimum rest period of 9 to 11 consecutive hours immediately before beginning a flight duty period.
Healthcare Professionals
The Accreditation Council for Graduate Medical Education (ACGME) sets duty-hour standards for medical residents. These standards limit the workweek to a maximum of 80 hours, averaged over a four-week period. Continuous duty periods for residents are typically limited to 24 hours. A mandatory 10 hours of rest must be provided between duty periods.
The Impact of Fatigue and Safety Regulations
Extended work periods, especially those exceeding 12 continuous hours, significantly increase the risk of errors and accidents due to sleep deprivation and diminished cognitive function. Studies have shown that injury rates are substantially higher during night shifts and after a worker has been on duty for an extended duration. The Occupational Safety and Health Administration (OSHA) addresses these risks through its General Duty Clause. This clause requires employers to provide a workplace free from recognized hazards that are likely to cause serious harm. Although OSHA does not set specific hour limits for most workers, the agency can cite employers if excessive working hours have created a recognized fatigue hazard leading to injury.
Special Considerations for Young Workers
Federal law imposes the most stringent limits on the working hours of minors. Under the FLSA, 14- and 15-year-old workers in non-agricultural jobs face strict daily and weekly limitations. When school is in session, these young workers are limited to a maximum of 3 hours on a school day and 18 hours during a school week. Their work hours are also restricted to the period between 7:00 a.m. and 7:00 p.m., with the evening limit extended to 9:00 p.m. during the summer. Once a worker reaches 16 years of age, federal law lifts these hours and time-of-day restrictions.