11 Results from Our Thermometer Types Comparison

5. Mercury/glass thermometers (legacy)

Mercury glass thermometers were once the household standard for accurate readings, but safety concerns have pushed them out of everyday use. These thermometers rely on mercury expansion in a glass tube to indicate temperature, and they can be accurate when functioning properly. The major drawback is risk—if a glass thermometer breaks, mercury exposure and sharp glass are hazards to people and pets. Disposal and cleanup require special handling through hazardous-waste channels. As a result, most health authorities do not recommend mercury thermometers for home use, and many retailers no longer sell them. Reading times are relatively slow compared with modern digital devices, often requiring several minutes. In practice, there’s little reason to keep a mercury thermometer in a home with children or older adults; digital alternatives deliver similar accuracy without the same safety risk. If you find an old mercury thermometer in a family drawer, consider replacing it and disposing of it safely per local hazardous-waste guidelines rather than keeping it as a backup.