Leica Geosystems introduced the first hand-held laser distance meter in 1993. Although there are now at least 17 brands and 42 models on the market, most of us still exclusively use our familiar steel tape measures. But postings on various builders' forums indicate that the mindset among pros is gradually changing as they gain trust in laser-measuring technology and realize the benefits.
Laser distance meters, or LDMs, work by bouncing a visible laser beam off a stationary surface. They receive the reflection through a lens, calculate the phase shift or time of flight, and translate the results into a digital measurement. The simple point-and-click operation normally delivers a measurement in less than a second and allows you to measure by yourself with minimal walking and climbing.
LDMs can quickly measure existing architecture for preparing floor plans and elevations, and some are ideal for estimating and takeoffs. Finish carpenters have discovered that well-equipped models are faster and more accurate than tapes when running baseboard, crown moldings, chair rail, and long top casings, or when squaring up jambs for wide or tall doors. Some models can find the angles for stair skirts and handrails.
The meters have limited value for framing, but they do make it easier to frame walls in place, fit tall posts, and measure between rim boards to size long joists. You can also use them to plan staging, determine which of your ladders will reach a roof, measure between deck posts for infilling top and bottom rails, and so on. Tapes are still required, however, for taking very short measurements, transferring dimensions to your stock at the cutting station, and measuring to a layout mark, an edge, or an outside corner (unless you put a target there).
You can buy a basic LDM for around $100 (or less) that's accurate to within 3/32 inch. At the other extreme, $350 to $800 buys advanced features, such as built-in scopes or cameras that make it easier to aim at distant targets or in bright light, and integrated Bluetooth for transmitting data to Excel, AutoCAD, and other programs.
For this article, I evaluated 13 state-of-the-art models that cost about $115 to $280 and are accurate to within 1/16 inch or better. In my opinion, that's the sweet spot for most residential and light-commercial work. I used the tools for several weeks, then compared their features, performance, and ease of use.
The spec chart on the next two pages lists the range and accuracy for each model. To measure at the maximum distance, though, you need to aim the laser at a target plate like the ones sold by Bosch, Hilti, and Leica. These plates increase the measuring range and effectively magnify and brighten the dot for easier viewing. Aiming at typical building materials can reduce the range by 20% or more. Bright light, high temperatures, and unpredictable surfaces such as shiny metal can all cause measuring problems, but you'll normally receive an error alert rather than an incorrect measurement when conditions are unfavorable.
Outdoors, the biggest issue is being able to spot the laser dot from a reasonable distance or in bright light. Using a target plate is one solution, but you have to position it and account for its thickness, which is extra work.
Laser-enhancement eyeglasses, on the other hand, make it easier to spot the dot without adding any extra steps. Wearing Hilti's optional PUA 60 glasses, I could (with plenty of concentration) find the dot from more than 150 feet away when measuring to shaded yellow metal siding, virtually doubling my viewing range. When I tried to measure to a sunny section, I could barely see the dot at 10 feet without the glasses, but with them I could pick it out of the glare at 50 feet. Prices for laser-enhancement glasses start at about $10.
Five of the meters I tested can mount to a tripod, which also makes it much easier to hit a distant target.
I found that most of these LDMs can measure lengths down to about 2 to 4 inches, but three of them needed more than a foot of separation to record a measurement.
According to Stanley Tools, short FatMax tapes are accurate to 1/16 inch, not counting sag or temperature fluctuation. Long tapes are typically less reliable, declining to 1/2-inch accuracy at just 33 feet. By comparison, nine of the LDMs are supposed to be accurate to 1/16 inch, and four to 1/25 inch.
Some manuals recommend that you periodically verify the accuracy by setting up a fixed target at a known distance from the meter (Hilti recommends about 3 to 15 feet) and measuring the distance 10 times to check for deviation. I clamped a 2-by stop to one end of a kitchen island and used my FatMax tape to position a hardwood block 11 feet away to serve as a target, then took 30 shots with each model. I repeated the test another day with a white target plate. All 13 models passed the tests, straying within limits only occasionally.
Units of Measurement
All 13 models can measure in fractional inches, feet and inches, decimal feet, and metric units. The Leica Disto E7300 and E7400x and the two Stanley models also display decimal inches, while the Bosch GLM 80, Hilti PD 5, and Spectra Precision QM75 and QM95 can show decimal inches and yards. For finish carpentry, I appreciate the models that display fractions down to 1/32 inch. Six of the models do that, while the rest go down to 1/16 inch.