How to Read a Thermometer? And How Not to Make Common Mistakes

You would be surprised how many people can not use a thermometer correctly. If you need to read a temperature, then you should know how to do it properly. There are many ways to measure a temperature and many ways to get it wrong.

If you can’t get to a doctor or are in some emergency scenario, getting exact readings at different times of the day might be important to make any diagnosis.

With many different types of infections out there, some of which make the body take lower temperature recordings in the morning than in the evening, it’s important to get it right.

Here are a few things to look out for to get the right readings.

How to Use a Thermometer?

There are several different types of thermometers with the most effective being rectal, though oral is the most commonly used.

  • ArmpitAxillary” – A thermometer is placed under the armpit.
  • Ear “Tympanic” – A thermometer takes the temperature in the ear.
  • Forehead “Temporal” – The thermometer takes a reading on the forehead.
  • Mouth “Oral”– This is your normal oral cavity thermometer.
  • Anus “Rectal”– The thermometer is placed just inside the anus.

The video below gives you a breakdown of the different ways you can take a temperature

Here are a few Mistakes People Make

You can avoid some of the common mistakes that are often used when taking a temperature. Inaccurate readings will lead to improper diagnosis and make things challenging to treat.

A Digital thermometer gives different readings because:

1. Not waiting 15 minutes after eating or drinking

To get the most accurate reading possible, wait at least 15 minutes before taking the temperature. This allows any food or drink in your mouth to clear from the oral cavity. Hot food and cold drinks can influence the temperature of your mouth making the reading not very reliable.

2. Holding the thermometer too close to their lips

When measuring the temperature, ensure the thermometer is held firmly under your tongue. Many people often just place the thermometer in their mouths or lips which will not give an adequate reading.

3. Holding the thermometer for not long enough.

Keep the thermometer under your tongue for at least 20 seconds. If you leave the thermometer in for a shorter period then it is likely that you will not get a proper reading.

Common Questions People Have

Should I use skin or ear thermometer?

You can use the skin or ear thermometer, but it is not as accurate as an oral thermometer. If there is a fever, you can take a more precise oral reading if you find skin or ear easier.

How and why would I take a rectal temperature?

A rectal temperature, surprisingly or not, is the most accurate way to get a temperature. It is especially easiest for young children who are not yet able to hold a thermometer under their tongue. It only needs to go in a half-inch and keep in place for 1-2 minutes. It is the same type of thermometer used as an oral thermometer, so be sure to have a separate one for each type of use.

What is a normal temperature?

The average body temperature is 98.6F, although normal body temperature can range from 97 F and 99 F or more.


There are many ways to take a temperature. Avoid the few common mistakes and you should have no problem getting an accurate reading.


[1] Fever: First aid.

[2] How do I take a temperature?

[3] How to Use a Thermometer to Check for Fever.

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