Are Amazon Thermometers Any Good? Temperature Accuracy Tested

Yes, a thermometer bought on Amazon can be a good choice for checking a fever, but accuracy depends on the model and how you take the reading. For an adult who can comfortably hold a probe under the tongue, I'd start with a digital oral thermometer. If you prefer a faster check, Global Swanky's ear and forehead thermometer collection gives you both types to compare. Check the intended age and measuring instructions for the individual model before you buy.

What did temperature accuracy tests actually find?

A 2021 clinical study tested six commercially available non-contact forehead thermometer models in 1,113 adults. Researchers compared the forehead readings with an oral reference thermometer. At one end of the results, a model read about 0.9°C low on average, roughly 1.6°F. At the other end, a model read about 0.2°C high on average, roughly 0.4°F. Two devices that look similar on a shopping page can give meaningfully different results.

The word average matters here. Adding 1.6°F to a forehead reading at home would be a mistake. That figure described one model across a group of adults. It can't tell you how far off a particular reading is, and it doesn't apply to every forehead thermometer. The researchers also didn't test every device now sold on Amazon. Their findings give buyers a reason to look for evidence about the exact model they're considering.

For a shopper, there's a practical question behind those figures. If a family member feels ill and the display shows a surprisingly low temperature, would you know how to check the result? A thermometer with readable instructions and a measurement method you can repeat is a better purchase than one whose main selling point is a one-second reading.

Which type of thermometer should you buy for home use?

Start with who will use it. An adult taking their own temperature may find an oral probe easiest. A parent buying for a child needs to consider age and whether the child can stay still for that method. Mayo Clinic lists oral thermometers as an option from about age four, when a child can cooperate. For a young infant, ask the pediatrician which method to use.

Think about an ordinary evening at home. If you drink tea throughout the day, an oral thermometer is still a reasonable choice, but you'll need to wait after your last cup. If you're buying a forehead scanner to share between caregivers, make sure everyone can find the correct measuring distance in the instructions. Those small differences matter more in daily use than the size of the display.

How can you judge an Amazon thermometer listing before buying?

Look for the manufacturer, exact model number and intended use. You should be able to tell whether the thermometer measures human body temperature, which part of the body it measures and who can use it. A product photo of someone aiming a device at a forehead tells you less than a manual that identifies the model and explains the procedure.

Pay attention to what an accuracy claim actually describes. A screen that displays 98.6°F can show tenths of a degree. That final digit tells you how the display rounds a reading. It doesn't tell you how closely the thermometer matched a reference when people used it. A laboratory check against a controlled heat source and a clinical comparison on real people answer different questions. If a listing advertises “clinically tested,” look for the model tested and the results.

Use reviews for details buyers can reasonably observe. Can someone read the screen in a dim room? Is it easy to switch accidentally from Fahrenheit to Celsius? Does the printed manual match the device in the box? A reviewer can give a useful answer to any of those questions. A comment saying “it matched my old thermometer” leaves out how each reading was taken and whether either device had been checked against a reference.

Why can a forehead thermometer give different readings a minute apart?

A non-contact thermometer measures infrared energy from the forehead. A damp hairline, a hat you've just removed or a change in the angle of your hand can affect the result. The FDA advises using the device indoors, away from drafts and direct sunlight, with the sensor facing a clean, dry, uncovered forehead.

One detail that's easy to miss is the temperature of the device itself. Say a thermometer arrives on a cold porch and you open the package in a warm kitchen. Before trying it, check how long the manual says to leave it in the room. The FDA gives a typical adjustment time of 10 to 30 minutes. That waiting period is for the thermometer to adjust to its surroundings.

Then check the measuring distance. If you've replaced an older scanner, the new one may need to be held closer or farther away. The correct distance comes from the instructions for that model. If two caregivers get different results, have each demonstrate how they hold the scanner. You may spot the difference before either person presses the button.

How do you check an unexpected temperature at home?

First, repeat the measurement using the same thermometer and body site after correcting anything that could have affected it. If the result still seems inconsistent with how the person feels, use another age-appropriate method if available. When speaking with a clinician, report the readings you saw and where you took them.

1. Read the unit on the screen. Check whether the display shows °F or °C. If the device has separate body and object settings, use the setting identified in the manual for taking a person's temperature.
2. Check what happened just before the reading. For an oral measurement, MedlinePlus advises waiting 20 to 30 minutes after eating or drinking something hot or cold. A reading taken immediately after ice water is a poor comparison for one taken later.
3. Repeat the method carefully. For an oral probe, place the tip under the tongue and close the mouth. For a forehead scanner, uncover and dry the measuring area, then follow the stated distance.
4. Write down the reading and the method together. “100.2°F orally at 8 p.m.” tells a clinician more than “about 100.” If you also took a forehead reading, record that separately. Avoid averaging readings from different body sites.

A home comparison can reveal a settings error or a problem with technique. It can't establish a thermometer's exact accuracy. If the same unit repeatedly gives implausible results under the conditions in its manual, contact the manufacturer with the model number. Global Swanky's guide to checking thermometer model details for recalls is relevant if you're trying to determine whether a notice applies to your unit.

When should you act on a reading instead of testing again?

For a baby younger than three months, call the pediatrician right away for a rectal temperature of 100.4°F (38°C) or higher. If a baby this young seems ill or you suspect a fever, seek medical advice promptly. Trying several thermometers to see whether one gives a lower number can delay that call.

For a household purchase, my choice would be a digital oral thermometer for an adult who can use one comfortably. I'd choose a forehead model when the convenience matters and the instructions clearly explain how to get a dependable reading. When comparing Global Swanky's digital thermometers or an Amazon listing, look up the exact model before paying extra for a claim about accuracy.

Frequently asked questions

1. Are inexpensive Amazon thermometers accurate enough for home use?
Price alone can't answer that. Look for a thermometer intended for human body temperature, a method appropriate for the user and clear instructions for the exact model. For an adult who can take an oral reading, a basic digital probe is a reasonable starting point.

2. Did the clinical study test every thermometer sold on Amazon?
No. Researchers evaluated six commercially available non-contact forehead models in adults. The findings show how much performance varied among those models. They don't provide an accuracy score for a current Amazon listing, an ear thermometer or a device used on a newborn.

3. Should I add a degree to a forehead temperature?
No. Record the number displayed and identify it as a forehead reading. The difference between measurement sites varies, and the clinical study found that some models read low on average while another read high. A fixed correction can make the result more misleading.

4. Does getting the same reading twice prove the thermometer is accurate?
Two matching readings show that the device repeated a result under those conditions. Accuracy is a different question: how close was the result to a suitable reference? A scanner can produce a consistent reading even when the user holds it at the wrong distance each time.

5. Can I test a forehead thermometer in ice water?
Keep it out of the water. The FDA says most non-contact infrared thermometers should never be immersed. An ice bath also can't verify how a forehead model estimates human body temperature. Use the manufacturer's instructions if you suspect your unit needs service.

6. Why is my oral reading lower after drinking cold water?
The drink can temporarily affect the temperature inside your mouth. Wait 20 to 30 minutes before taking another oral measurement. If you're keeping a temperature log, note that the earlier reading was taken immediately after a cold drink.

7. Does a normal temperature have to be exactly 98.6°F?
No. That's a familiar average. Body temperature varies between people, by time of day and by measurement site. A thermometer showing a slightly different value when you feel well isn't, by itself, evidence that the device is faulty.

8. Can I use an infrared thermometer sold for cooking to check a fever?
Choose a model specifically labeled for human body temperature. A kitchen or workshop device measures surfaces for a different purpose. If a household model offers both body and object modes, check which mode is active before taking a person's temperature.

9. Which thermometer should I buy for a newborn?
Ask your pediatrician about a digital rectal thermometer and how to use it correctly. The American Academy of Pediatrics uses a rectal reading of 100.4°F (38°C) or higher as the fever threshold that warrants an immediate call for a baby younger than three months.

10. What should I tell my doctor if two thermometers disagree?
Give both readings, the times and the body site used for each. Mention anything that could have affected the measurement, such as a cold drink before an oral check. Include how the person feels. That gives the clinician more useful information than selecting whichever number looks closer to normal.