In place of a built-in footrest, some chairs come with a matching ottoman.

Design considerations for chairs have been codified into standards. ISO 9241, "Ergonomic requirements for office work with visual display terminals (VDTs) -- Part 5: Workstation layout and postural requirements" is the most common one for modern chair design.
There are multiple specific standards for different types of chairs. Dental chairs are specified by ISO 6875. Bean bag chairs are specified by ANSI standard ASTM F1912-98 [2]. ISO 7174 specifies stability of rocking and tilting chairs. ASTM F1858-98 specifies plastic lawn chairs. ASTM E1822-02b defines the combustibility of chairs when they are stacked.
The Business and Institutional Furniture Manufacturer's Association (BIFMA)[3] defines BIFMA X5.1 for testing of commercial-grade chairs. It specifies things like [4]:
chair back strength of 150 pounds (68 kg)
chair stability if weight is transferred completely to the front or back legs
leg strength of 75 pounds (34 kg) applied one inch (25 mm) from the bottom of the leg
seat strength of 225 pounds (102 kg) dropped from six inches (150 mm) above the seat
seat cycle strength of 100,000 repetitions of 125 pounds (57 kg) dropped from 2 inches (50 mm) above the seat
The specification further defines heavier "proof" loads that chairs must withstand. Under these higher loads, the chair may be damaged, but it must not fail catastrophically.
Large institutions that make bulk purchases will reference these standards within their own even more detailed criteria for purchase. [5] Governments will often issue standards for purchases by government agencies (e.g. Canada's Canadian General Standards Board CAN/CGSB 44.15M [6] on "Straight Stacking Chair, Steel" or CAN/CGSB 44.232-2002 on "Task Chairs for Office Work with Visual Display Terminal").
Chairs may be rated by the length of time that they may be used comfortably — an 8-hour chair, a 24-hour chair, and so on. Such chairs are specified for tasks which require extended periods of sitting, such as for receptionists or supervisors of a control panel.


In place of a built-in footrest, some chairs come with a matching ottoman. An ottoman is a short stool intended to be used as a footrest but can sometimes be used as a stool. If matched to a glider, the ottoman may be mounted on swing arms so that the ottoman rocks back and forth with the main glider.
A chair cover is a temporary fabric cover for a side chair. They are typically rented for formal events such as wedding receptions to increase the attractiveness of the chairs and decor. The chair covers may come with decorative chair ties, a ribbon to be tied as a bow behind the chair. Covers for sofas and couches are also available for homes with small children and pets. In the second half of 20th century, some people used custom clear plastic covers for expensive sofas and chairs to protect them.
Chair pads are cushions for chairs. They contain cotton or foam for padding. Some are decorative. In cars, they may be used to increase the height of the driver. Orthopedic backrests provide support for the back. Some manufacturers have patents on their designs and are recognized by medical associations as beneficial [7][8][9]. Car seats sometimes have built-in and adjustable lumbar supports. These can also be used on kitchen chairs.
Chair mats are mats meant to cover carpet or hardwood flooring. They are usually made from plastic. This allows chairs on wheels to roll easily over the carpet and/or protects the carpet or floor. They come in various shapes, some specifically sized to fit partially under a desk.
Remote control bags can be draped over the arm of easy chairs or sofas and used to hold remote controls. They are counter-weighted so as to not slide off the arms under the weight of the remote control.
Chair glides are attached to the feet of chairs to prevent them from scratching or snagging on the floor.