To take an ear temperature, you gently insert the tip of an infrared ear thermometer into the ear canal, wait for the beep, and read the result. The whole process takes a few seconds, but small details like pulling the ear in the right direction and waiting after being outdoors can make the difference between an accurate reading and one that’s off by a degree or more.
Before You Start
Ear thermometers work by measuring infrared heat radiating from the eardrum, so anything that changes conditions inside the ear canal can throw off your reading. A few quick preparations help:
- Wait 15 minutes if you or your child has been outside in very hot or cold weather. Extreme air temperatures temporarily affect the ear canal and can skew results.
- Don’t measure on an ear that’s been pressed into a pillow. Lying on one side warms that ear. Switch to the other ear or wait a few minutes.
- Wash your hands with soap and warm water.
- Attach a clean probe cover if your thermometer uses disposable tips. A torn or missing probe cover can produce abnormally high readings.
- Clean the thermometer before and after each use with rubbing alcohol or soap and lukewarm water if it doesn’t use disposable covers.
How to Pull the Ear (It Depends on Age)
The ear canal isn’t a straight line. It curves slightly, and that curve runs in a different direction depending on age. Pulling the outer ear straightens the canal so the thermometer’s sensor has a clear path to the eardrum. If you skip this step, the sensor may read the canal wall instead, giving you a lower number.
For adults and children older than 3, grasp the top of the outer ear and gently pull it upward and backward. This straightens the canal enough for a clear reading. For babies between 6 months and 3 years, the canal curves in the opposite direction, so pull the outer ear downward and backward instead.
Step-by-Step Instructions
Turn the thermometer on and wait for the ready signal (usually a light or display prompt). With your free hand, pull the ear as described above. Gently insert the thermometer tip into the ear canal, angling it toward the eardrum. Don’t force it deeper than the instructions indicate. Most consumer models have a built-in stop that prevents you from inserting too far.
Hold the thermometer snugly in place so it doesn’t shift. You’ll hear a beep within one to three seconds, depending on the model. Remove the thermometer and read the number on the display. If you’re using a disposable probe cover, eject it without touching it and discard it.
For the most reliable result, take two or three consecutive readings in the same ear. Expect variation of about 0.2°C (roughly 0.4°F) between measurements. If one reading looks like an outlier, use the highest consistent number.
What Counts as a Fever
A fever measured by ear thermometer is 100.4°F (38.0°C) or higher. This is the same threshold used for rectal and forehead readings. On average, ear thermometers produce similar mean results to rectal thermometers, though individual readings can vary more, which is why pediatricians sometimes prefer rectal measurements for very young or high-risk children.
Age Limits for Ear Thermometers
Don’t use an ear thermometer on a baby younger than 6 months. Infant ear canals are too small and curved for the sensor to get a reliable reading. For babies under 6 months, a rectal thermometer is the most accurate option. After 6 months, ear thermometers work well for most children and adults.
What Affects Accuracy
Earwax is the most common culprit behind inaccurate readings. A significant buildup of wax can block some of the infrared signal from the eardrum, pulling the displayed temperature down. Research has shown that removing a heavy wax blockage raises the reading by about 0.2°C (0.4°F) on average. You don’t need a perfectly clean ear canal, but if wax is visibly blocking the opening, try the other ear or clear the wax first.
Ear infections also pose a problem. An inflamed, swollen canal can distort readings in either direction. If the ear you’re measuring is sore, red, or draining fluid, switch to the other ear or use a different type of thermometer entirely.
A small or unusually curved ear canal, common in younger children, can also reduce accuracy. If you consistently get readings that seem too low or too high compared to how your child feels, try comparing with a forehead or rectal reading to see how your particular thermometer tracks.
Troubleshooting Common Problems
If you get an unusually low reading, check the probe cover and thermometer tip for obstructions, and make sure the ear canal itself isn’t blocked by wax. An unusually high reading often points to a damaged probe cover with tears or gaps, so replace the cover and try again.
A blank display means the battery is dead. Most thermometers will show a battery icon before they die completely, giving you a heads-up to swap in fresh batteries. If your thermometer displays an error code and won’t clear it after you install a new probe cover, the most common cause is a rapid change in ambient temperature. Let the device sit at room temperature for about 20 minutes, then try again. This often happens when you bring a thermometer in from a cold car or garage.
Tips for Measuring Children
Young children tend to squirm, and even a small shift during the one-to-three-second measurement window can aim the sensor away from the eardrum. Sit the child on your lap facing sideways, and use one arm to hold their head gently against your chest while you insert the thermometer with your other hand. Pull the ear down and back for children under 3, up and back for older kids.
If your child has been lying on one ear, measure the other one. A pillow-warmed ear can read noticeably higher. And if they’ve just come in from playing outside in cold weather, wait the full 15 minutes before measuring. Rushing the reading is the single most common reason parents get numbers that don’t match how their child looks or feels.