Bosch GLM 50
At the moment, this model has the lowest price in the group. It's also the most intuitive, with no baffling key combinations. But although it shows fractions down to 1/32 inch, calculates areas and volumes, can add and subtract, and can measure indirectly, there's no timer, memory, or tailpiece, and tracking doesn't register minimum and maximum lengths. The display's backlight is controlled by a light sensor with no manual override. This sometimes left me in the dark — for instance, it dimmed and then turned off while tracking. Also, there's so much ghosting when viewing the display from below that it can be hard to read. The laser clicks when it records a measurement, but it doesn't beep to confirm operations like the other models do, which might be a problem on a noisy site.
Bosch GLM 80
The rechargeable GLM 80 is the only model under $200 that has an inclinometer. It isn't the most rugged model, but it displays fractions down to 1/32 inch, can handle direct and indirect measuring with ease, and has all the other perks I would want, from a timer to an erasable memory. For $250, you can buy a kit that includes Bosch's R60 attachment, which quickly expands the meter into a 24-inch digital box-beam spirit level. I found that this combo isn't as convenient as the advanced 24-inch Stabila electronic level I use (which has more helpful audio signals, for instance), but it was just as accurate after I quickly calibrated the inclinometer. The microsite at boschtools.com does a great job of demonstrating all of the GLM 80 features.
Hilti PD 5
This two-button laser is designed for installation work, period. It measures distances, has a tracking mode, and is long and slender so you can slip it into a narrow toolbelt pocket and grab it easily. You can also hose it off. But you have to press and hold the on/off button for two seconds to enter the menu and then manipulate both buttons to change the units of measure or control the beep, so it isn't completely intuitive. Also, the display is upside-down when shooting from left to right. Several models have more features for less money, but Hilti has the only lifetime warranty.
Leica Disto D2
The D2 offers all the critical measuring options you need for estimating and installing, plus deluxe amenities like a timer, a memory, and a tailpiece. It also fits into small pockets and feels just right in my hand. When it was introduced in 2008, it displayed fractions down to 1/32 inch; now it displays 16ths instead.
Leica Disto E7300
A step up from the D2, the E7300 is one of four models tested that are accurate to 1/25 inch and display fractions down to 1/32. It also has a longer range than the D2, can delete the memory so you can start a new list, allows you to shoot a common ceiling height just once when calculating the total area of a series of walls, and more. It doesn't have a timer, and you have to remember some two-key combinations to set the units, lock the keypad, and control the backlight and beep. With minor refinements, this model would be one of my favorites.
Leica Disto E7400x
A video at leica-geosystems.us shows this new model being tossed around a job site, dropped from a stepladder into a gravelly puddle, and dunked into a water bucket to clean it off. Besides having a class-leading IP65 rating for dust and water protection and passing Leica's 2-meter drop test, the E7400x is tied for first in accuracy and has a full complement of deluxe features, including an inclinometer. There's a learning curve, but the graphic manual is a big help.
This tool has the same engine, display, and endpiece as the Leica Disto D2. But Milwaukee added an extra key and rearranged the keypad so it's slightly more convenient. It also added rubber bumpers and offers a five-year warranty versus Leica's three-year one. One problem I found was that, when measuring flat surfaces with the 2280-20 on its back, I often had to raise the front of the tool to prevent the beam from "scraping" the surface and throwing off the measurement.
Spectra Precision QM55
The new QM55 offers the basic options you need for estimating or installing at a comparatively low price. It's the first LDM I've seen that has a signal-strength indicator, which displays up to four bars to help you aim at an appropriate target. It also has the biggest memory, storing up to 50 measurements and calculations. According to Spectra, it's drop-tested from 1.5 meters. On the downside, the tool is heavier than most, requires more button clicks, doesn't have a timer, and makes you insert a separate tailpiece for measuring from inside corners. You also can't turn off the beep, which may only be an issue for work in an occupied office or other quiet zone.
Spectra Precision QM75
This new model works just like the Hilti PD 5 and has an identical display. But the QM75 is shorter, wider, and thicker than the PD 5, so it's a bit less convenient in my toolbelt. Then again, the QM75 has been drop-tested from 1.5 meters while Hilti makes no drop-test claims. The QM75 also costs about $50 less than the Hilti but comes with a three-year warranty versus a lifetime one.
Spectra Precision QM95
This new long-range laser is accurate to 1/25 inch and displays 32nds. Like the other Spectras, it has been drop-tested from 1.5 meters, so it's rugged. But despite its higher-than-average price, it lacks several useful features such as min/max, a timer, and a memory. It's also the biggest and heaviest of the lot.
Stabila LD 400
Like the Milwaukee 2280-20, this model is fundamentally the same as the Leica Disto D2, adding a rubber bumper and extra buttons. But Stabila's crowded keypad is the hardest of the three to navigate, and it gives no indication that the memory button also activates the timer. Last time I checked, the Stabila cost $70 more than the other two models.
Stanley TLM 165
Of the 13 models tested, only the Bosch GLM 50 costs less than the new TLM 165. The two models are similar, except the Bosch shows fractions down to 1/32 inch and has a tripod socket, while the Stanley has a small memory, a tailpiece, and a ghost-free display. Overall I prefer the Stanley, though I wish it displayed 32nds. Stanley's manual, by the way, didn't mention that you can turn the beep on and off by pressing the function and unit keys simultaneously for a second.
Stanley TLM 330
In the spec chart, the new full-featured TLM 330 and Leica 7400x appear to be almost identical. But the Leica rates at IP65 rather than IP54 (which means you can hose it off), while the Stanley adds an extra Pythagoras function and a leveling mode that uses beeps to indicate level — handy if you can't see the display. The Stanley also has four more keys for quicker access to several functions, but I think they clutter the keypad without significantly improving the tool. For instance, a new key makes it easier to calculate triangular areas (which I've never done), but you still need to use an obscure key combination to turn the backlight on and off. The Stanley currently costs about $15 less than the Leica, but comes with a two-year rather than a three-year warranty.
The Bottom Line
A decade ago, the cheapest LDM cost $360 and was accurate to 1/8 inch. Compared to that, every one of these models is a bargain. All are exceptionally accurate, and all will measure lengths with simple pointing and clicking. There are definitely differences in convenience, though. I quickly came to appreciate extra features like timers, memories, estimating shortcuts, and the ability to measure indirectly around obstacles.
My overall favorite is the innovative Bosch GLM 80. It's an especially quick estimator, easily measures indirectly, reads angles, has a bright rotating display, uses a rechargeable lithium-ion battery that delivers up to 25,000 measurements per charge, and is priced below the average. An optional attachment quickly converts it into a 2-foot electronic spirit level. The full-featured but pricier Leica 7400x and Stanley TLM 330 finished a close second.
But not everyone needs the same features. The best choice for you depends on the type of work you do.
Bruce Greenlaw is a contributing editor at The Journal of Light Construction, which is where this article first appeared.