how does a laser measure work

Laser tape measures are fantastic tools that allow you to measure long distances with a high degree of accuracy. These devices fire a concentrated laser beam at your target object. This ray of light is reflected back at the tape measure. Using the principle of how fast light travels, the laser tape measure can then calculate the time the beam took to reflect, and thus calculate the distance between the two points!

These ingenious measuring tools are easy to use and are incredibly accurate, too. Forget about the traditional measure! Invest in a laser distance meter instead so you can make your DIY work and home improvements that much easier to complete! In this guide, we look at exactly how does a laser measure work, the components of a laser distance meter, how to use one, and tips of how to get an accurate measurement every time – enjoy!

An Overview of How Laser Measures Work

distance measuring tool

This type of measuring tool calculates distance via firing a laser beam. The beam is made of light. We know that light travels at a certain speed through the air (something like 300 million metres per second for those who want to know!). This rule can be used together with the speed/distance/time triangle to calculate distances!

In this triangle, you must know two of the factors to be able to calculate the third variable. So, we know the speed i.e. how fast the laser light travels. Once the laser beam is fired at the target and then reflected, we can measure the time it took for this to happen. This means we now have speed and time. Therefore, to calculate the distance, the measure simply has to multiply the speed by the time!

It is this simple calculation process and use of basic rules of physics that allows this type of measure to be incredibly accurate, and give you measurement readings of a distance instantly.

The Makeup of Laser Measuring Tools

First, let’s look at the construction of laser measures. What components do they have? What do they look like? And what are their main features? The technology within laser measurers is complex, however, their construction and features are easy to understand:

Display Screen

All laser distance meters have a display screen. The screen is usually either LCD, backlit LCD, or LED. More expensive laser distance meters will have better quality screens and may even feature touchscreen technology.

The screen is where your measurement information is displayed. It is also the place where you can access the instrument settings and menus.

Laser Lens

One of the most important parts of this instrument is the lens. This is the component that the laser is fired through and what projects the laser beam at your target. It has complex optics that allow the creation of a concentrated laser that can travel across long distances. The laser lens is usually located on the top side of the tool, above the screen.

Pro-Tip – Always keep the laser lens clean and free from obstructions. This helps improve the accuracy of the laser.

Laser Receptor

To calculate the distance, the laser beam must reflect on a surface, and fire back into the device. The method of capture is the laser receptor. This sensor accepts the light streak that has been reflected back from the target object. Using the principle of reflection, and the speed at which light travels, it can then calculate the distance between the device and target.

Power Source

This tool must also obviously have a power source to work. There are two main types of power sources for a laser distance meter – either traditional AA/AAA or rechargeable batteries. Traditional battery models are less prevalent now and they are less convenient to use as you have to keep replacing the batteries.

However, most modern laser distance meters use Li-ion batteries. These are rechargeable. Usually, you can charge them via a dedicated charging station, but many models now offer USB charging.

How to Use a Laser Distance Meter

So how do you use a laser measure? Once you understand the basics and have used the tool a few times, you will find it incredibly easy to measure. We have described basic usage steps below for both single and multiple distances:

Single Distance Measuring

The most common calculation people use the tool for are single distances. For example, if you want to measure the distance between two walls, to see if a piece of furniture will fit. The following process generally applies:

  1. Turn the tool on
  2. Select the correct measurement function
  3. Place the back of the measure against the first surface you wish to measure from
  4. Point the measure towards the target surface
  5. Press the relative measure button to fire the laser
  6. Read the measurement from the display screen

a man measuring the interior height of a cabinet As you can see, this is an incredibly simple process and takes a few seconds to complete. Before using your tool, we advise reading the instruction manual fully. This will give you a clear overview of how the laser light works. Also, it will show you the different functions, how to interpret the display screen, and what the various buttons are for.

When using these tools, it is important to place them flat against the surface you wish to measure from. They are calibrated to automatically subtract the distance from the laser to the back of the measure. Therefore, if you don’t place it flat against the surface, you won’t get an accurate reading.

Also, it is important for the line to be as straight as possible. If you fire the laser light at an angle it could also give an inaccurate measurement. The display screen is usually easy to understand. It will show the measurement in larger numbers once you have pressed the relevant measurement button. Also, you can usually swap between imperial and metric measurements.

Multiple Distance Measuring

Most tools also have a function that allows you to measure multiple distances and add or subtract the distance. For example, you may want to measure the overall distance between two walls that are separated by a partition. The following is the general process for multiple distance measuring:

  1. Turn the tool on
  2. Select the correct measurement function
  3. Place the back of the measure against the first surface you wish to measure from
  4. Point the measure towards the target surface
  5. Press the relative measure button to fire the laser
  6. Press the plus or subtract button
  7. Repeat steps 3 to 5 to measure the next distance
  8. Read the measurement from the display screen


Essentially, you are taking a series of individual readings, but using the add and subtract functions in-between each measurement to get an overall distance reading. You can do this for any number of measurements. Plus, this function can greatly reduce the work and manual calculations you would usually need to complete.

Tips for Best Usage of Your Laser Measures

Now that you have a firm grasp of how laser measures work, we can give some general tips that should help you use them more effectively. They can be fragile tools so it is important to look after your measure, clean it, and store it properly if you want it to last for a long time.

1. Add a spirit level to your measure for greater accuracy.

For the most accurate distance measurements, the line you project needs to be straight and at the right angle. For example, if you measure from one wall to another, and the laser line you project is at an angle, this may add unnecessary distance and skew your measurements.

A way to combat this is to attach a spirit level to your laser measuring tool. You can easily get separate spirit levels that are not attached to another tool from a hardware store. Once you have a level, tape it securely to the measure. It is important that the spirit level bubble is aligned properly with the laser measure. It should be laid flat on the top of the measure without obstructing the screen. Also, it should be aligned horizontally so that the bubble is pointing the same way as the laser beam outlet.

2. You get better results from highly reflective surfaces.

To get accurate measurement data and better performance, the surface you are pointing the laser beams at should be reflective. As discussed above, this gadget works on a principle that involves reflections – the laser beam hits the target surface, and is reflected back at the receptor.

As a result, if the surface you are aiming at is dull and unreflective, the effectiveness of the laser distance measure is reduced.

3. Consider marking the end target with a post-it note.

When you are measuring over long distances or in confined spaces, it can be difficult to target the exact spot you want to measure towards. This may not matter if you do not need accuracy to a few millimetres. However, if you need precise measurements, you could consider marking the target spot with something.

A post-it note is a simple way to do this. You could attach a post-it note to the target object or surface and even make a pen mark in the middle of the post-it note that you want to fire the laser beam at. This will provide a clear target for you to aim the laser measure at and ensure that your measurements are incredibly accurate.

4. Regularly clean your laser distance measure.

a father measuring the height of his son Over time, as with any tool, laser distance meters will become dirty. It is, therefore, important to clean your laser regularly. This is a quick and simple job and should only take a few minutes maximum.

The most important parts to clean are the display screen and the laser lens. If the laser lens gets dirty and covered in dust and grime, it could affect the beam and cause it to be less accurate. Also, keeping the display screen clean is important so you can actually read it and the measurements you are taking! You can clean your device with a wet cloth or a cleaning wipe and always place it in a carry case for portability and protection.

5. Never use the laser pulse measure near flammable materials.

Laser measures generate a concentrated beam of light that contains energy and heat. As a result, they should never be used in environments with flammable or explosive materials. The result can be disastrous.

You could fire the laser and potentially start a fire, or even cause an explosion. The likelihood of this is not huge, however, is it always important to use these tools responsibly and with extreme care. Check the area you want to measure beforehand to make sure any dangerous materials are removed.

6. Never point the laser light at people or animals.

Following on from the above point, it is also important to never point the laser at animals or people. You never know how someone may react to a laser. In minor instances, the laser could cause skin irritation and skin damage. In extreme cases, if you point a laser in someone’s eyes, it could cause blindness.

We understand the temptation to use a laser measure like a simple laser pointer, but this is not what it is meant for and if used recklessly, it can be dangerous and harmful.

Laser Measure FAQ

To further help you get more familiarised with this tool, we’ve answered a couple of questions about its usage and common features.

What is the maximum distance you can measure with a laser?

Generally, 20 metres is the maximum distance that the laser beam will travel and reflect. However, this will vary depending on the range and power of the individual model

Can you use laser measuring tools outside?

Yes, however, using the measure outside in a bright area can make it more difficult to see the dot on the target plate you are pointing the gadget at.

How accurate is a laser measure?

Their accuracy primarily depends on how you use them. However, you can count on a high degree of accuracy from your laser measure. Typically, they are accurate up to 1/8 or 1/16 of an inch.

Measuring With Ease

Now you can answer if somebody asks you ‘how does a laser measure work?’. With all these tips and tricks, we hope you make the most out of your laser measuring device and do not hesitate to use it the next time you’re moving furniture!

Let us know what you use your laser meter for in the comments.

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