How Accurate Are Infrared Thermometers?

How Accurate Are Infrared Thermometers?

Learn how to compensate for reflective surfaces and ensure accurate readings, and discover tips for calibration to guarantee consistent accuracy across different tests.
Table of Contents

Infrared thermometers use thermal imaging to accurately measure the surface temperature of objects. They do this by detecting infrared radiation emitted by an object’s surface, then correcting for emissivity to provide an accurate reading.

Infrared thermometers can be employed in a number of ways, including home inspections and DIY projects. They’re also helpful when cooking or doing auto repair work, as well as measuring the internal temperatures of the body, solid foods, and liquids.

  • Accuracy

The accuracy of an infrared thermometer depends on several factors, including its emissivity, distance-to-spot ratio (D/S), and field of view. Generally speaking, the higher the D:S ratio, the farther away a thermometer can accurately measure surface temperature.

Furthermore, the temperature of a target may be affected by any steam or dust between it and the thermometer. Furthermore, dirty or scratched lenses on the thermometer may deflect some of the infrared energy required for accurate readings.

Infrared thermometers can be inaccurate when measuring shiny or reflective objects, so to compensate, you should use a non-reflective target. For instance, you could place tape over metal surfaces to get an accurate reading or put flat paint on glass surfaces to get a better reading.

  • Distance to Spot

When using infrared thermometers, the D:S ratio is an essential factor to take into account. This figure tells you the diameter of the “circle of surface area” an IR thermometer will measure at a given distance – an accurate indication of what temperature it can read.

The D:S ratio can also determine how close to a target you should place the thermometer for optimal readings. Generally, devices with a D:S ratio of 1:1 or lower should be held as close as possible for accurate results, while higher D:S instruments may be used at much farther distances for accurate measurements.

Another essential feature of a medical infrared thermometer is emissivity, which measures how well an object emits infrared energy. This factor should be taken into account when taking measurements from shiny or reflective surfaces that tend to reflect light rather than absorb it.

  • Field of View

One of the most crucial elements in getting accurate readings from an infrared thermometer is its field of view. This refers to what measurement spot its lens can capture as the distance between itself and the surface being measured increases.

Infrared thermometers come in two varieties, handheld portable units or permanently mounted ones. Handheld portable thermometers have a narrow field of view and can be used for maintenance and troubleshooting tasks like testing printed circuit boards, motors, and bearings up close.

Fixed-mount laser thermometers are installed in a specific location to continuously monitor a process. These units tend to be more ruggedized, featuring NEMA or ISO industrial-rated enclosures. They typically output 4-20 mA process control signals.

  • Temperature Range

Non contact infrared thermometers are widely used in a range of industries to quickly and precisely measure surface temperatures from a safe distance. They help prevent accidents by identifying potential trouble areas and averting potentially hazardous failures before they take place.

Infrared thermometers typically measure temperatures from a few hundred degrees Fahrenheit up to several thousand degrees Fahrenheit, making them ideal for detecting elevated temperatures on mechanical equipment, electrical circuits, and building systems.

  • Calibration

Calibration is an integral component of non contact thermometer operation and must be done regularly to guarantee accurate readings across various applications. It should be performed to prevent errors and guarantee consistent accuracy across different tests.

Infrared thermometers are calibrated using reference radiation sources, also known as black bodies. These provide a stable range of temperatures over an extended period.

Before beginning calibration, a black body should be placed in an area that won’t be reflected by any surfaces. Furthermore, the use of purge gas prevents ice and moisture accumulation on the surface.


Caretek Medical Infrared Thermometers are perfect for a number of uses. From detecting drafts to catching a fever, these thermometers are user-friendly, precise, and handy. They’re ideal for checking the temperature of objects with their different types of thermometers, like in ear infrared thermometer or gun type infrared thermometer. The best-infrared thermometers are user-friendly, accurate, and long-lasting enough to withstand regular use. If you want to know about what is an infrared thermometer in detail, then give this a read.


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