How Laser Levels Work

A laser level will make hanging pictures a cinch. See how a home is built by viewing these home construction pictures.
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Here's the situation: You're standing on your couch with a hammer and nail in one hand and a level in the other. You're trying to hang a series of framed pictures, but you want them hung in a straight line -- after all, this isn't a Leaning Tower of Pisa sort of above-the-couch gallery. Problem is, it's physically impossible for you to hold the level against the wall while you also hammer in a bunch of nails. You'd need an extra arm to accomplish such a task, and you don't have one. If only the level could hold itself against the wall, and you could hammer away at the nails with both of your two free hands.

Guess what? If you had a laser level in your toolbox, this wish would be reality. A laser level projects a visible and perfectly straight line across a surface like a wall or floor. Since many laser levels mount to a tripod or even to the wall, that leaves your hands free to hammer in nails or line up tiles. A laser level simplifies do-it-yourself projects like hanging wallpaper, putting up tile for a kitchen backsplash, installing a long shelf or cabinet or building a deck.

You might think that, because the tool has the word "laser" in it, it would be an expensive addition to your collection. But laser levels are actually pretty cheap. You can buy a simple model for as little as $20.

Laser levels are found throughout the construction, cabinetry and civil engineering industries, and they're commonly used for concrete and asphalt work. Grading, landscaping and surveying companies also rely on laser leveling systems. Framers use laser levels to check for square alignment of openings like windows, doors, dormers and skylights.

So if the experts are using these tools, why shouldn't you give a laser level a try?

The Technology Behind Laser Levels

Laser levels use a laser, an amplified, focused beam of light emitted from a solid-state device called a diode. These light emitting diodes, also known as LEDs, are found in many common devices, including digital clocks, remote controls, or television screens.

To understand how a laser works, it's helpful to know that the word is really an acronym for Light Amplification by the Stimulated Emission of Radiation. Simply put, when certain electrons are stimulated, they give off a beam of light. When mirrors or prisms collect this light and point it in one direction, the result is a laser beam.

Laser levels project a beam of light that can be used as a visual chalk line when a straight and level reference point is needed. The size of the beam of light depends on the size of the diode. In this case, smaller is better -- a smaller beam of light is more precise. With a wider beam of light, the actual point of "level" can be located anywhere within the width of the beam.

The first laser levels were limited to indoor use because the light of the laser was not bright enough to be seen outdoors. Today, more powerful laser levels can be used indoors or outdoors, and many are designed for use with a light detector that "reads" the laser's light. These devices are positioned away from the laser's diode, then moved up or down until the projection is detected and signaled in response with a beep or blink.

Most lasers emit a red beam of light. Some manufacturers are now offering green lasers that are 400 percent brighter than red laser beams, making them more visible for indoor applications. However, the technology that's needed to project green requires more power than a red light, so battery life is not as long lasting, and the red lasers are generally more accurate and more reliable over a range of temperatures.

Laser levels are usually manufactured with small, low-intensity diodes and are powered using rechargeable or alkaline batteries. As with any laser, looking directly at the light can be harmful to a user's eyes, so wearing safety goggles is always recommended. The light of a laser level should not be directed at another person.

Now that you know how these lasers work, let's learn how to use them.

How to Use a Laser Level

Laser levels are easy to use, and with a variety of designs available, there's a style that suits any application. Different types of laser levels have been developed for specific uses, but all laser levels include two common components: the laser plus a leveling base that can sit on the floor, mount on the wall or attach to a tripod. This base helps you to project the light at the required height. There's also a leveling mechanism, either a bubble vial or a pendulum and magnets plus electronic sensors (the differences between these two types of mechanisms will be discussed below). The enclosure, or case, is usually made of a durable plastic or metal that's tough enough for sturdy performance on a job site.

Laser levels find "level" in different ways. Manual laser levels work in the traditional way: The user lines up a bubble inside a vial either by repositioning the level or turning a knob. Well-suited for typical do-it-yourself projects, these laser levels are less expensive and require less battery power than a self-leveling unit.

Self-leveling units offer a greater degree of accuracy. They work best when placed on a surface that the user determines is "close to level." You can use a bubble vial to manually level the unit before the unit's self-leveling mechanism takes over. The laser component hangs like a pendulum inside the level. Magnets and gravity work together to still the pendulum, and the beam is then projected through a light or prism.

Some laser levels are equipped with electronic self-leveling sensors that boost accuracy and reliability, and they are ideal on a busy outdoor construction sight. For indoor jobs where the level is moved around frequently, a self-leveling mechanism helps to save time and increase reliability.

Types of Laser Levels

Several different types of laser levels are available, varying in application and cost:

  • A point generator is the simplest type of laser level. It's basically a spirit level that shoots a laser dot and sometimes incorporates a line generator that can be flipped down in front of the beam.
  • Dot lasers project a simple point that can be level, square or plumb. A wide variety of models are available that range in price from $20 to over $500. While the least expensive models are best suited to indoor use, other models can be used outside.
  • A line laser is a point-to-point level that can shoot several horizontal and vertical laser lines using multiple LED diodes over a distance of 65 to 100 feet (19.8 to 30.5 meters). Designed for indoor use, they often include plumb up and plumb down capabilities. Some models now include a pulsing light technology that works with a light detector so that they can be used outdoors or in bright indoor spaces. Prices vary from $40 to over $600.
  • Rotary lasers levels project a rotating dot to create a 360 degree line. A detector is used for reading the laser lines over a long distance. Most rotary lasers also have single line generators and plumb up, plumb down capabilities. Ideal for outdoor work, such as grading roads, laying foundations, or laying pipe, these are the most accurate and the most expensive laser levels, varying from $250 to over $2,000. Manual and self-leveling options are available, and they can be operated by a remote control. Some rotary levels, designed for grading or foundation work, are so large they need to be mounted on a platform or a tractor.

As its technology was refined over the past decade, laser levels have become more accurate, smaller, easier to use, and more affordable. Once only found on large construction sites, now small and large contractors find that laser levels can turn two- or three-man jobs into one-man tasks.

Today's laser levels allow engineers or contractors to lay out a building or site design more quickly and accurately than ever before, with less labor. In some industries, such as airline and shipbuilding, lasers provide real-time feedback comparing the layout to the actual CAE/CAD files, and it's very likely the same technologies will be available for large construction projects and homebuilding soon.

Some laser levels are even being equipped with Bluetooth wireless technology to transmit their dimensions to a handheld computer, providing site-specific information on the spot.

As laser technology itself improves, the benefits will be reflected in additional features for levels. Self-leveling models and remote control options will continue to grow and improve. And as prices continue to fall, laser levels of all types will find their way into more and more toolboxes.

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More great links


  • Baker, Stuart. "Lasers on the Job Site." Fine Homebuilding. December 1996/January 1997.
  • Jeske, Ryan. "Leveling the field: what's new in the highest of high tech lasers?" Construction Distribution. October 2005.
  • Katz, Gary. "Laser Levels: Bet You Can't Buy Just One." Fine Homebuilding. December 2006/January 2007.
  • Tomasulo, Katy. "Level headed: the latest laser levels continue to offer contractors new features, greater accuracy, more efficiency." ProSales. August 1, 2002.