Unlike the fragile mercury-filled products of the past, today's digital thermometers give speedier (typically 30 seconds or less) and more accurate readings, and feature more user-friendly designs. There are several ways to get a reading with digital thermometers including oral, rectal, tympanic (ear), forehead and axillary (underarm).
Accuracy varies a good deal depending on the type of thermometer used. Theoretically, they're all pretty much equal, but certain types are more difficult to set up for a good reading.
Rectal temperatures are generally regarded as the most accurate, particularly for babies who can't hold an oral thermometer in the right position. The downsides of rectal thermometers is obvious. Both parents and kids may find them uncomfortable and stressful to use. Depending on the model, these readings may not be exceptionally rapid, and when using a standard stick-style thermometer, it can be hard to tell how far to insert it.
Oral thermometers are usually very accurate, especially for adults and older children who can place them properly and hold still for the 30-60 seconds they take to produce a reading. Another upside is that the same type of thermometer can typically be used for oral, axillary or rectal readings. (For hygiene concerns, probe covers are usually available.)
Ear and temporal thermometers, when used correctly, can be just as accurate as oral and rectal thermometers while being far less invasive. They're also very rapid, taking 10 seconds or less. This makes them popular among parents in particular. Unfortunately, ear and temporal thermometers are plagued by inaccuracies.
Ear thermometers may be uncomfortable to insert depending on the thermometer or the age of the user. As a result, the thermometer may be inserted incorrectly and register an incorrect reading. Some models correct for this by only giving a reading when properly placed in the ear, but this can be just as frustrating for parents trying to get a quick temperature reading from a squirmy, sick child. Probe tips, used for hygiene, sometimes add to this issue.
Temporal thermometers take a series of over 1,000 readings while being swiped across the temporal artery in the forehead. The numerous readings allow the thermometer to select and display the single most accurate result. A reading can take mere seconds and is completely comfortable and noninvasive. However, many owners find it difficult to get the hang of the swiping motion, yielding inaccurate results.
Overall, reviewers and experts recommend going basic. Inexpensive, basic digital thermometers that read oral, rectal and underarm temperatures are considered to be the best value because they can provide accurate readings for individuals of any age. On the other hand, many people aren't prepared to sacrifice convenience and ease of use, making models that add bells and whistles popular.
To reconcile these two perspectives and identify the best digital thermometers in each category, editors analyzed thousands of owner-written reviews across sites such as Amazon.com, Walmart.com, Drugstore.com, Target.com and Viewpoints.com. A number of professional consumer testing organizations have also evaluated digital thermometers, including ConsumerReports.org, Which? magazine, Choice magazine and Consumer magazine. Editors looked for models that were accurate, easy to use and offered additional features that truly improved users' experiences.