I've been wanting to buy a laser level for several years now but, out of all the lasers on the market, I've been unable to decide which one would be right for me. There are many potential applications for a laser in a carpenter's routine, and just as many questions to answer in order to choose one instrument that's equal to all of these tasks.

Do I want a tool that shoots horizontal or vertical lines, or one that does both? What about one that projects two lines simultaneously at 90 degrees to each other? And what about dots? I definitely want plumb dots, but for horizontal applications, would I be better off with dots or lines? I can have either one with a 90-degree projection option, but do I want an instrument with a revolving dot instead?

As luck would have it, I was given the challenge of writing this review. It was probably the only way I was ever going to pick the right laser for my work, so that's what I set out to do.

During the course of my research, I discovered that — even among the mountain of lasers on the market — there is no perfect tool, although there are several close calls. A complete review of all the lasers available today would be nearly impossible, so I limited this article to covering self-leveling, non-rotating lasers that retail for no more than $600. (We'll look specifically at rotating lasers in a future article.) I also limited the coverage to tools that fit the needs of the general trades — carpenters, plumbers, electricians, hvac technicians, drywallers, and so forth.

In Search of the All-Purpose Laser

No matter which trade we're in, most of us would like a laser that performs a variety of similar functions. A level dot or line for laying out items such as cabinets, wainscoting, electrical boxes, and drain lines is surely a must. A split dot that projects a 90-degree angle is great for all kinds of squaring-up jobs. A plumb line that connects the floor, wall, and ceiling is extremely useful for accurate framing, jamb installations, and locating structural beams, deck piers, and recessed ceiling lights. Matching right-angle lines simplify the installation of flooring, tile, and decorative ceilings. And most of us would like our bright new laser to replace that old, spinning, swaying plumb-bob.

Dots and Lines

Right from the start, I had a hard time deciding between dot lasers and line lasers. Until recently, I thought that line lasers were best for use by flooring and ceiling installers, but these instruments are just as useful in other applications. A horizontal line is easier and faster to work to than a dot: No dot can match the usefulness of a line cast straight across the floor, up the wall, and back across the ceiling, plumb to its point of origin.

Unfortunately, the visibility of the line deteriorates rapidly as projection distance increases. Line levels are excellent in smaller rooms, like kitchens, closets, and bathrooms, cast on walls that are within 20 feet of the instrument. But lines aren't easily visible in brightly lit rooms or large rooms where the line must be cast farther than 30 feet. And the line levels I tested were not acceptable for exterior use at all.

Likewise, most dot levels are barely visible outdoors. But there are significant differences between individual dot lasers. Some tools have only one horizontal dot, while others employ a prism to split the laser and create two horizontal dots — the second dot at a right angle to the first. Other tools project three horizontal dots, all at perfect 90-degree angles. One thing that most dot lasers have in common is that they shoot plumb dots — up, as well as down.

Judging Quality

There are several characteristics that affect the quality of a laser. I graded each tool by the following criteria:

Dot size. Dot size varied dramatically from tool to tool, from 3/32 inch to 1/4 inch, but seemed to grow smaller as the price increased. Several manufacturers suggested that dot size wasn't that important, and that users should simply measure to the "center" of the dot. But finding the exact center of an extremely bright, sometimes fuzzy red dot can be difficult. For that reason, the smaller the dot, the better.

Dot clarity. Some manufacturers tout the brightness of their dots, while others claim that their dots are sharper than the next guy's. Both are subjective claims, relating to the clarity of the dot: Like the focus on a slide projector, some dots appear fuzzy, while others are tack sharp. Sharp dots tend to travel longer distances without degradation. Sharp dots are also easier to work with and ensure greater accuracy. I graded dot clarity on a scale of 1 (worst) to 10 (best).

Self-leveling. Although all the instruments in this review are self-leveling, I discovered that some dots moved out of level when the tool was jostled or moved. I therefore tested each tool for "constant" self-leveling. After placing the tool on a perfectly level surface and aligning the dot with a premeasured fixed point, I gradually shimmed the tool out of level until the laser beam or the safety light blinked or the instrument shut off. I measured the accuracy of the dot just prior to safety shutoff, and I measured the size of the shim that produced safety shutoff.

Dampening. I relied on subjective terms to evaluate the sensitivity of the pendulum dampening system (described below) in each tool, and how quickly it controlled a dancing dot. Systems that brought the dot to rest quickly were graded Good; I gave a grade of Fair to those that allowed the dot to dance in 8- to 10-inch orbits around the target as I walked across the floor of my raised-foundation home. A dot that jumped violently, skittered around the target, and remained nervous after I'd walked across the floor, earned a Poor rating.

Pendulum lock. Self-leveling lasers calibrate and correct themselves via a swinging pendulum mechanism. The pendulum levels the tool quickly, which saves considerable setup time. Most of these tools will self-adjust if the work surface is within approximately 5 degrees of level.

The pendulum system is so sensitive that several manufacturers include a pendulum-locking mechanism on their unit to safeguard the delicate instrumentation during travel, repositioning, and storage. Other manufacturers implied that a pendulum lock wasn't necessary for their tool.

Accuracy

Before testing any of the laser units, I set up my transit in my living room and established three reference points. I shot two opposing points across the longest distance (20 feet) inside my house, and, for each, I marked a fine ink line on masking tape, exactly at the cross hairs. For testing accuracy over a 50-foot distance, I opened the French doors in my living room, swung my transit, and marked the cross hairs by driving a 6d finish nail into a tree in my back yard. I checked the accuracy of these marks by relocating the transit in a second position and shooting all three positions again. The error factor was no more than 1/16 inch. (Although my transit is much more accurate than any $600 laser level, it takes longer to set up, occupies too much space in my truck, and can't shoot plumb lines or project reference points. Lasers have advantages in these areas.)

To test the lasers, I used a Stabila elevator tripod equipped with a rotating base. I leveled the mounting plate with a spirit level, then adjusted the elevator to align each of the lasers in turn with the first mark at the end of my hallway. Next, I rotated the tool to check the second mark and, finally, to the nail in my rear yard. To double-check the results, I moved the tripod to a second location and tested each tool again.