The Complete Handbook of Chair Mats

Chapter 1: Understanding Chair Mats

The functional definition of a chair mat

A chair mat is a rigid or semi-rigid panel placed between the casters of an office chair and the floor. It has three jobs, and only three jobs. First, it protects the floor underneath from the concentrated mechanical load of the chair's wheels. Second, it provides a smooth, low-friction rolling surface so the chair moves predictably. Third, it prevents the casters from gouging, staining, or abrading the floor material when the user shifts position. If a product does not do all three of these things well, it is not fulfilling the function of a chair mat, regardless of what the packaging claims.

The reason a chair mat is needed at all comes down to basic physics. A standard office chair carries the weight of a human being, and that weight is transmitted to the floor through an extremely small contact area: the caster wheels. A typical dual-wheel caster has two polyurethane or nylon wheels, each about 3 centimeters in diameter and 50 millimeters wide. When a person weighing 90 kilograms sits in a chair, the weight is distributed across five caster bases, so each caster carries roughly 18 kilograms. But that 18 kilograms is concentrated on a contact patch no larger than a few square millimeters. The resulting pressure at the point of contact can easily exceed 600 kilograms per square centimeter. That is more than enough to permanently indent a hardwood floor, crack a tile, or crush