How Does A Laser Distance Measure Work?

They have largely taken over the traditional tape measure in quite a few professional fields thanks to their ease of use, accuracy and low cost. They are laser distance measurers, sometimes also called laser meters, little electronic boxes that shoot a laser out of one end and provide you with an instant distance reading on the screen when you press the button.

But how do these electronic boxes work and why are they so accurate?

We will take a closer look at the laser measure and dig a little deeper into the various functions that they offer to get a better understanding about how they operate. Knowing more about them should provide you with the confidence to trust their results and may also help you to use them more effectively.

The Basics


When you press the button of your laser distance meter it sends out a finely focussed pulse of light. This beam hits the target point and then reflects back to the unit where it is picked up by the receiver. The measurement is carried out by working out the time it took for the beam to make that journey.

So, of course, what that means is that when you are taking a measurement there must be a spot to aim the laser at that will reflect the beam back to the device.

The really good quality laser measuring devices are able to return distance measurements that are accurate to within +/- 1/16” or around 1.5mm. The top of the line units have been found to operate with even greater accuracy of +/- 1/32”.

The Importance of Range

As with all tools, and particularly with electronic ones, there are a few different options available to you. One of these offers you a range at which the measuring device is effective at.

You can probably break the various laser measures down into 3 categories based on their measuring range.

  • 30 meter range - Home Use
  • 30 - 50 meter range - Professional Indoor Use
  • 50+ meter range - Professional Outdoor Use

The laser measures that offer the shorter ranges will prove to be particularly effective but their short range suggests the laser is not going to be as strong. Working around home, whether it’s inside or outside, you are most likely only going to need to be able to measure short distances so the lower range will be most suitable.

The medium sized laser measures prove to be quite robust devices and are perfect for real estate professionals or painters and decorators who need to be able to measure room sizes and wall areas. The most common types in this category are 50 meter laser measures and they tend to offer all of the functionality a professional requires on a work site.

The most powerful laser measuring devices will also provide you with the longest range and the most common of these are the 100 meter laser measures, although it is possible to buy them with longer ranges. These measures will be suitable for use on large sites and will work equally well outdoors and indoors. They will prove extremely valuable for those in the construction industry. 

Measuring Area and Volume

The on-board processing that is possible with most handheld devices provides the capabilities necessary to calculate area and volume.

By providing measurements for multiple points it is then possible for those units that have been designed with the area and volume features to perform some fairly straightforward calculations instantly. All you need for an area calculation is length and width measurements. To get a volume measurement you have to capture length, width and height measurements.

It is possible to calculate these mathematical equations yourself with a standard tape measure but it will be a much slower and onerous task and it will also leave room for mistakes.

Pythagoras Theorem

You may notice, when you browse through the extensive range of laser distance measures that some of them provide “Pythagoras” functionality. This is another way of saying indirect measurement.

This uses the well-known triangle equation of a2 + b2 = c2 . The way this can be done is by pointing the laser measure to 2 points to form 2 sides of a triangle and the third side will be calculated and provided to you.

The advantage of this is that it is possible to get readings for some of the more inaccessible spots that might otherwise require putting yourself in a dangerous or uncomfortable position to achieve. Not only that, it is far easier to stand in a single spot, point and click to get two sides of the triangle which will give you the reading for the third side.

Continuous Measure

Another feature that is available with some distance meters is a continuous measure function. This feature enables you to take a measurement from Point A to Point B and then will continue to update the reading result should you wish to move Point B.

The advantage of using a device with a continuous measurement function is that you can continually walk around taking quick measurements without having to stop to reset the starting point.

Calibrating Your Laser Distance Meter

In order to confirm that your laser measure is providing you with the correct results you should calibrate it before the first time you use it. This is a fairly simple process:

  1. Measure a length using a tape measure
  2. Mark the point where the physical measurement was taken
  3. Place the laser measure at the exact spot that the physical measurement was taken
  4. Turn the laser measure on
  5. Point the laser beam toward the target point
  6. Capture a reading my pressing and releasing the measure button
  7. Compare the reading against the distance that you measured out with the tape measure
  8. If there is a sizable difference found, the laser measure should be returned to the manufacturer either for adjustment or replacement

By confirming that the linear distance functionality of the device is accurate you are also confirming that the other features will also be true. This is because once the device captures a distance reading, all of the other features are done by calculation and this type of functionality can be done by any calculator.

Not only does a laser distance measure provide you with a tool that will help you measure accurately but it will also speed up the process, proving to be a valuable time saver. Quoting jobs single-handedly will take no time at all and you will also be able to store all of your measurements and, in some cases, shoot them straight back to the office.

They are definitely a piece of equipment that will prove extremely useful in a wide variety of fields and should be a consideration for adding to your toolbox.