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Most chairs are made to fit around 90 percent of people but those on the ends of the spectrum may not fit. Since there is no "average" person chairs are made in sizes that can be fully adjustable so that they can be made to fit most people. However, if you are very tall or very short then you may need a custom-made chair. Unless you get a custom-made chair, you should get a fully adjustable chair so that you can adjust it properly for your body. Choosing a chair with controls that are easy to operate while sitting will allow you to adjust your chair completely to your body. You can put yourself in the chair and then adjust all the pieces directly onto your body. Height is a very important factor when adjusting a chair so it is very important that the height of the chair can be adjusted according to your body and needs. Tilt is also important for allowing correct posture while sitting. The curve along the edge will provide more space for your knees and comfort on the backs of your thighs. Additionally, the seat should not put pressure on the back of thighs or knees. You don't want to get all sweaty while working at your desk nor do you want to slide around too much so these factors are important when choosing a chair. Adjusting the backrest to completely support your lower back will allow your to remain pain and injury free. The base should be a five-point system that provides balance and stability while sitting on the chair. The base should be on casters or wheels depending on your preferences. You should be able to easily get in and out of the chair but the armrests should be as close as possible while sitting. The closer your elbows stay to your body while sitting, the more comfortable you will be. Armrests should never hamper your movement while working or typing. Adjustable armrests will allow you to customize their height for your body size and arm length.
Choose the chair made for your body size. Choose a chair with controls that can be easily operated while sitting. Choose a chair with a seat that can be adjusted for height and tilt. Choose a comfortable seat that curves towards the floor at the front edge. Choose a chair with breathable, non-slippery fabric. Choose a chair with a backrest that is shaped to support the lower back and adjustable in height and angle. Choose a chair with a stable five-point base. Choose a chair with armrests that are the right distance apart. Choose a chair with adjustable armrests.