Bosch Laser Measure (GLM100C) - Canadian Woodworking Magazine

Make faster, easier, and more accurate longer distance measurements.

Bosch Laser Measure (GLM100C)

Bosch Laser Measure - GLM100C

If you've never used a laser distance measurer (aka laser tape, laser meter, digital tape) then you're in for a real treat. You'll still need your tape measure for short distance measurements, but for longer distance measurements a laser tape is faster and easier to use, much more convenient, and a lot more functional – it can calculate square footage and volume, and keep track of your measurements. A laser won't sag like a tape measure, it doesn't need a buddy to hold the other end of the tape, and it doesn't require you to climb a ladder or scoot on your knees in a crawl space - all you do is point and click. 

Lasers work by sending out a beam of laser light to a target, and measure the time it takes for the reflection to return. An integrated circuit works out the exact distance based on this information, or calculates the area and volume from multiple measurements.

Lasers come in a fairly wide range of price points with various features. The Bosch GLM100C is a premium laser with just about every measurement mode that you're ever likley to use. It will be of particular interest to carpenters, renovators, architects, plumbers, painters, electricians, building inspectors, real estate agents, landscapers, and the like. 

Compact design and light in weight

The GLM100C is a compact 1-1/8" by 2" by 4-3/8" – not much larger than a smartphone – and weighs just 5 ounces (with the battery installed). Unlike many other lasers, it comes with a built-in rechargeable 3.7 V, 1.25 Ah Lithium-ion battery. It takes about 3-1/2 hours to fully recharge the battery, via the USB port on the back of the laser ('A' in the photo above), but you get an incredible 25,000 measurements or so on a single battery charge. You can charge the laser with your computer (via the included micro-USB cable), or with the included mini charger, This is a much better arrangement than having to constantly purchase and replace disposable batteries. 

Also on the back of the laser is a 1/4" tripod mount ('B' in the photo) and a positioning pin ('C').

The GLM100C comes with a decent carrying case that you can attach to your tool belt by means of a Velcro strap. I find this type of strap a bit awkward to use, and much prefer a standard metal belt clip, which is quicker to attach and remove.

The laser also comes with an instruction manual, which is, typical of most manuals, very poorly written. This is unfortunate, considering that you do need to read the manual thoroughly in order to understand how to use the GLM100C to its fullest potential. However, Bosch also includes a useful shortcut guide that fits in the carry case and provides helpful reminders while you get accustomed to the unit.

The business end

On the top end of the laser are two lenses. The smaller one is where the laser beam comes from The larger lens receives the reflected beam, and using the rate of return, determines the distance that the laser is from the surface.

This laser is listed as having a measuring range of up to 330'. I assume this is under ideal conditions. Inside, or on cloudy days, you'll likely get the full distance. I had no problem taking indoor measurements up to 210'. But, on bright sunny days you'll be lucky to take a measurement at half that distance, as the laser beam (in reality the red laser dot) is difficult to see in direct sunlight. Taking measurements off a reflective surface such as glass, steel, or marble is problematic as well. You'll need to attach some kind of opaque material to the reflective surface (I tape on a 4" square piece of black Bristol board).

The measuring accuracy is listed as +/-1/16". I wasn't prepared to test this over a very long distance, but I did measure out several short distances with my tape measure, and then checked the distance with the GLM100C (mounted on a tripod). The result was spot-on.

For rough measurements you can just hold the laser in your hand. But unless you hold it rock steady you'll get variable readings. Whereever possible it's best to rest the laser on a stationary surface. Otherwise, mount it on a tripod. Even then the slightest vibration will affect the reading – which really only matters if you need measurements down to the nth degree.

A nice bonus is that you can use the GLM100C as a laser pointer when you need to draw someone's attention to a feature that's out of reach. A note of caution here - don't direct the laser beam towards anyone's eyes – not just bad form, it can result in a serious eye impairment.

Easy to read screen in any lighting condition

The 1-1/4" square backlit screen is very easy to read, even in the brightest light, and at whatever angle the laser is tilted. After about 12 seconds of inactivity the screen dims somewhat to conserve battery power, and after a further 30 seconds of inactivity the screen dims a bit more – almost dark, but still readable. Just press any button to illuminate the screen to full brightness.

The GLM100C is supposed to have a built-in intelligent light sensor that ensures the display automatically adjusts depending on the brightness of the surroundings. This feature didn't work on the laser I tested, and there was no reference to it in the manual. Unless it referred to the aformentioned screen dimming.

The blister-type push buttons are proud of the surface, making them easier to depress, and also keeping out dust and moisture. The buttons also make a tactile click when pressed (though you can turn this feature off).

You can also display measurements in imperial or metric units, and in various measurement units, including fractions (e.g. 35-19/32"), inches with two decimal places (e.g. 21.78"), feet/inches in fractions (e.g. 2' 11-78'), and both feet and yards to three decimal places (e.g. 3.111', 1.059 yds). Switching from one unit of measurement to another takes about 10 seconds.

Rotating display

When you turn the laser on its side the display rotates – a feature that I haven't, as of yet, found particularly useful. However, the laser can be mounted on the Bosch R60 measuring rail to transform the laser into a digital level. As I don't have an R60 I can't attest as to how well this works.

Top: Outside measuring; Bottom: inside measuring

The folding positioning pin is likely to see a lot of use. I didn't mind that it's made of plastic, and I am glad to see that it's easily replaceable. The pin enables you to take outside (position the pin at 90° to the laser) and inside (position the pin straight out) measurements. The result you get will be extremely accurate. You need to 'inform' the laser when you use the pin – you do this by pressing the 'Measuring Reference' button on the keypad (see below).
Keypad layout is intuitive and easy to memorize

The keypad might look a bit confusing at first, but I found that once I used the various keys a few times their functions were fairly easy to remember. In any event there are only a few buttons I regularly use. The two most frequently used buttons 'On/Off' and 'Measuring' (or 'fire the laser') are bright red and in the center of the pad. The rest of the buttons have visual clues (icons) on their surface that are fairly intuitive.

The laser has 9 measuring modes:

  • length
  • area
  • volume
  • continuous min/max
  • indirect height
  • double indirect height
  • indirect length
  • multi-surface area
  • angle
Additionally there are a range of basic settings you can customize (units of measure, display illumination, tone signal, etc), as well as features for adding and subtracting measurements, setting up timed measurements, store up to 50 consecutive measurements, transmitting data to any Bluetooth enabled device, and downloading data to your computer.

There really are too many features to attempt to learn all of them at once. I suggest you begin with a few of the basic (and likely most useful) features, and add other functionality as the need arises.

Measurement reference options

As mentioned above, each time you use the folding positioning pin to make an inside or outside measurement you'll need to tell the laser. When you turn on the laser it defaults to the rear edge position (the bottom edge of the laser). Simply press the 'Measuring Reference' button to select a new reference point, which will appear in the top left portion of the screen (red circles above). Each time you turn the laser off it resets to the default setting (rear edge).

Basic measurement modes

90 percent of the measurements I make are length and area. The 'Measurement' button is conveniently placed directly to the right of the power button. When you power on the laser it defaults to the length measurement, so all you need to do is point and fire. As you begin taking readings the measurements will appear on the top right of the screen. Each time you press the 'Measurement' button it advances to the next measurement type. You'll quickly associate the various symbols (red circles in the photo above) with the measurement type, as they're all very intuitive – a line, a rectangle, a cube. 

Up to 4 measurements visible on screen in length mode

When taking length measurements (which accounts for 75 percent of what I use the laser for), the three most recent measurements will appear on the top right of the screen – which means you can have up to four measurements on your screen at any one time. The current measurement is at the bottom of the screen (3'07" in the photo above), while the preceding measurement moves to the bottom of the list (3'04"). You can preview your last 50 measurements by pressing the 'List/Storage' button on the lower right of the keypad. The values appear in reverse order – the last measured value first. I find this a very useful feature as I no longer have to write down the measurements. The measurements remain in memory even after you turn the laser off. They only disappear as you enter new measurements, or if you delete the measurements in memory. You do this by pressing the 'List/Storage' and 'On/Off' buttons simultaneously.

Additional measurement modes

The other measurement modes (continuous min/max, indirect height, indirect length, etc) are accessed through the 'Func' (Function/Basic Settings) button. Once you've become familiar with the three direct measurement modes (length, area, volume) you can tackle these other modes. The only one that I use somewhat regularly is the 'Wall Surface' mode, which enables me to quickly calculate the area of a room when the height is consistent for all the walls. You measure the room height just once, and then step through the room, measuring all the walls. The laser calculates the total cumulative surface area.

Grade (angle) measurement mode

The GLM100C has a built In tilt sensor that displays 90° angle measurements with the laser placed on its side or back.Each time you press the 'Grade Measurement' button it switches the axis. It has an accuracy of +/- 0.2°, which makes it very sensitive. I find it impossible to get an accurate measurement holding it in my hand, but on a stationary surface, or tripod, it's a different story – instant accuracy.

Download data to your computer

After you install the free GLM Transfer software onto your computer you can download the up-to-50 measurements stored in the laser to a text file or spreadsheet on your computer. The data is simply listed in sequential order. If you've taken a series of measurements in a predefined order, without any deviation, then you might remember what each measurement actually relates to. In most situations though, you'll want to keep a written list of what the measurements refer to. But, if you do that, it's probably just as fast to write down the actual measurements at the same time – which is why I don't find this feature of much value.
I'm probably one of the very few people in Canada who doesn't use a smart device, so I wasn't able to try out the Bluetooth feature. However, Bosch does have a short overview of how it works and a link to where you can download the smartphone app: Learn more about using Bluetooth with the GLM100C. 

After using the Bosch GLM100C for the better part of a month I'm hooked on its versatility and practicality. I like its small size and light weight, it's intuitive keypad, the clear backlit LCD screen, the ability to use fractional units, the display of the 4 most current length measurements on-screen, the tripod mount (which I find indispensable), the convenient USB charging system, and the integrated lithium-ion battery that provides an amazingly long run time. While I don't use all nine of the available measurement functions regularly, it's nice to know that they're available if I do need them. The GLM100C does take some investment of time to get used to all the features, but the learning curve isn't as steep as I thought it might be.
While I've only been using the GLM100C for a month, there isn't much I don't like about it. The data download feature proved to be a bit lackluster, and the manual was downright irritating.
If you do a lot of measuring, then I'm convinced that you'll save time and money with a laser measurer. It's a product for which you'll quickly see a positive return on your investment. If you don't need all the functionality that the GLM100C offers, then check out the Bosch GLM15. For around $50 you get a simple point and click laser tape that provides linear measurements up to 50'.


  • Battery: Rechargeable 3.7 V, 1.25 Ah Li-ion
  • Charging Time: 3-1/2 hours
  • Dimensions: 1-1/8" x 2" x 4-3/8"
  • Weight: 5 ounces
  • Leveling Accuracy (Vial): +/- 0.2°
  • Measuring Accuracy Typical: +/-1/16-in
  • Measuring Range: 2" -  265' (typical); 2" - 330' (maximum)
  • Measurement Modes: length, area, volume, angle, min/max, continuous, single indirect height, single indirect length, combined indirect height
  • Vertical or horizontal screen display
  • Auto switch off: 5 minutes
  • Bluetooth wireless connectivity
  • Remote controllable by smart device
  • Warranty: 2 years
  • Includes: Charger, micro USB cable, belt pouch

MADE IN:Malaysia
SOURCE:Where to Buy
August 2014

Carl Duguay
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