When you work with a laser distance measure, or a rangefinder often, you may rely on exact measurements. However, not all tools are perfect, and over time it's possible that your device will gain and lose distance. Thus it's important to make sure you have calibrated the device, before and after important measurements at the very least. This is actually more of a mathematical process that allows you to determine how accurate your device is.
Locate a space you can stand or rest the rangefinder on, which faces a measurable space -- ideally, one which is exactly one or two meters or yards away. Measure the distance with your measuring stick.
Write down the exact distance between the rangefinder and the point opposite with the measuring stick. Keep your paper on a clipboard, so you can jot things down while you work.
Use the rangefinder to determine the distance and write that down. Repeat this stop at least 10 times to get a more precise average.
Subtract the rangefinder distance from the measuring stick's distance. This will tell you how much the rangefinder deviates from the measuring stick.
Calculate the standard deviation for that deviation. You can simplify this by using the Standard Deviation calculator located under Resources. This number will tell you, on average, how far off your measuring device is from the standards. If your device is off by a considerable amount, return it to the factory for readjustment.
Your device may come with a tool or a procedure for realigning the laser or altering the device. Consult your manual to determine how you can adjust your laster measuring tool. For more precise measurements, use a measuring stick or tape acquired from the National Institute of Standards.