How Much Weight Can Tempered Glass Hold?

Much like the human heart, glass is vulnerable to breakage. But since you probably don't let the threat of a broken heart stop you from loving, you shouldn't allow the threat of broken glass stop you from enhancing your home décor with glass. Tempered glass tables and shelves can add a modern, elegant flare to your space. And while glass may be fragile, tempered glass is resilient, minimizing the risk of injury in case of breakage.

The secret to tempering glass lies in how quickly it is cooled after exposure to high levels of heat. First the glass is cut to size and all fabrication operations like etching or edging are completed prior to the heat treatment. Once the glass is ready for tempering, it is heated in an oven at about 620 degrees Celsius or higher.

The hot glass is then subjected to a rapid cooling procedure called "quenching," in which an array of nozzles shoots high-pressure blasts of cold air at the surface of the glass, forcing the surface to cool at a faster rate than its center. The quenching process is what gives tempered glass its strength because it causes tension to remain in the center of the glass while shifting the outer surfaces into compression. This also means that the edges of tempered glass surfaces are weaker than the center.

Glass in compression is stronger than glass in tension. Tempered glass, which breaks at about 24,000 pounds per square inch (psi) when made to federal specifications, is about four to seven times stronger than regular glass, which breaks at 6,000 psi. In addition to its increased resistance to breakage, tempered glass is designed to break off into smaller fragments that are less likely to cause serious injury.

While tempered glass is stronger than regular glass, it still has its limits. Maximize the longevity of your glass table or shelf by determining and then adhering to its weight limits. How much weight your tempered glass piece can hold depends on a variety of factors including width, height, thickness and distance between supporting brackets. Fortunately, glass load calculators are freely available online.

All you need to do is enter the data for the factors listed above and the weight limits for your specific tempered glass table or shelf will be calculated automatically. For example, a tempered glass shelf that is 11 inches wide by 16 inches long and 3/16 of an inch thick with one foot between supports could hold approximately 239 pounds. Never try to load a glass table or shelf with more weight than it can support.