In SSR 83-10, the Social Security Administration defines the different exertional levels of a job. Social Security defines each level based on how much weight can be picked up, how long a person can sit and stand, how long a person can walk etc.
Lifting and carrying is limited to 10 pounds or less, standing and walking is limited to under two hours out of an eight hour day. The majority of the time is spent sitting. However, a job can allow you to alternate between sitting and standing, and still be considered a sedentary job.
The regulations define sedentary work as involving lifting no more than 10 pounds at a time and occasionally lifting or carrying articles like docket files, ledgers, and small tools. Although sitting is involved, a certain amount of walking and standing is often necessary in carrying out job duties. Jobs are sedentary if walking and standing are required occasionally and other sedentary criteria are met. By its very nature, work performed primarily in a seated position entails no significant stooping. Most unskilled sedentary jobs require good use of the hands and fingers for repetitive hand-finger actions.
“Occasionally” means occurring from very little up to one-third of the time. Since being on one’s feet is required “occasionally” at the sedentary level of exertion, periods of standing or walking should generally total no more than about 2 hours of an 8-hour workday, and sitting should generally total approximately 6 hours of an 8-hour workday. Work processes in specific jobs will dictate how often and how long a person will need to be on his or her feet to obtain or return small articles.
The standing and sitting maximums are flipped: sitting is limited to 2 hours out of an eight-hour day, and standing is limited to 6 hours out of an eight-hour day. Lifting increases from 10 pounds to 20 pounds occasionally, and 10 pounds frequently.
The regulations define light work as lifting no more than 20 pounds at a time with frequent lifting or carrying of objects weighing up to 10 pounds. Even though the weight lifted in a particular light job may be very little, a job is in this category when it requires a good deal of walking or standing, the primary difference between sedentary and most light jobs. A job is also in this category when it involves sitting most of the time but with some pushing and pulling of arm-hand or leg-foot controls, which require greater exertion than in sedentary work; e.g., mattress sewing machine operator, motor-grader operator, and road-roller operator (skilled and semiskilled jobs in these particular instances). Relatively few unskilled light jobs are performed in a seated position.
“Frequent” means occurring from one-third to two-thirds of the time. Since frequent lifting or carrying requires being on one’s feet up to two-thirds of a workday, the full range of light work requires standing or walking, off and on, for a total of approximately 6 hours of an 8-hour workday. Sitting may occur intermittently during the remaining time. The lifting requirement for the majority of light jobs can be accomplished with occasional, rather than frequent, stooping. Many unskilled light jobs are performed primarily in one location, with the ability to stand being more critical than the ability to walk. They require use of arms and hands to grasp and to hold and turn objects, and they generally do not require use of the fingers for fine activities to the extent required in much sedentary work.
Medium work requires almost constant standing or walking, or kneeling, squatting, bending, climbing along with lifting 50 pounds occasionally and up to 25 pounds frequently.
The regulations define medium work as lifting no more than 50 pounds at a time with frequent lifting or carrying of objects weighing up to 25 pounds. A full range of medium work requires standing or walking, off and on, for a total of approximately 6 hours in an 8-hour workday in order to meet the requirements of frequent lifting or carrying objects weighing up to 25 pounds. As in light work, sitting may occur intermittently during the remaining time. Use of the arms and hands is necessary to grasp, hold, and turn objects, as opposed to the finer activities in much sedentary work, which require precision use of the fingers as well as use of the hands and arms.
The considerable lifting required for the full range of medium work usually requires frequent bending-stooping. (Stooping is a type of bending in which a person bends his or her body downward and forward by bending the spine at the waist.) Flexibility of the knees as well as the torso is important for this activity. (Crouching is bending both the legs and spine in order to bend the body downward and forward.) However, there are relatively few occupations in the national economy which require exertion in terms of weights that must be lifted at time (or involve equivalent exertion in pushing and pulling), but are performed primarily in a sitting position, e.g., taxi driver, bus driver, and tank-truck driver (semi-skilled jobs). In most medium jobs, being on one’s feet for most of the workday is critical. Being able to do frequent lifting or carrying of objects weighing up to 25 pounds is often more critical than being able to lift up to 50 pounds at a time.
Heavy and very heavy work:
Heavy and very heavy work is any work above the median exertional category. It involves jobs lifting up to, or more than, 100 pounds. The heaviest and most difficult construction work, often including construction cleanup, may be characterized as heavy or very heavy work.