Laser Levels To check laser level calibration before use, do the following: 1. Note one axis of laser as X1 and opposite side X2 (front to back). 2. Note other axis of laser as Y1 and Y2 (left to right). 3. Set up the laser level instrument on a level surface or tripod. 4. Turn on receiver and place in finest grade mode 5. Take a reading on a fixed vertical surface at 150 to 200 ft from laser and mark as X1. 6. Rotate the instrument 180 degrees and take a second reading and mark as X2. 7. Rotate laser 90 degrees and take a 3rd reading and mark as Y1. 8. Rotate laser 180 degrees and take a 4th reading and mark as Y2. The readings must be within the particular laser level’s specification and if they are not, the instrument needs to be calibrated. (review the specification sheet for your laser for tolerances). Do not assume that a slope laser that is within calibration in the level mode is accurate when used with a grade value entered. You will be required to perform a simple mathematical calculation to determine the departure from level at a said grade value and distance. Since one percent of slope at 100 feet is equal to 12 inches (1 foot), you would expect to have 18 inches of fall at 150 feet and 24 inches (2 feet) at 200 feet.