It is important to know how to check calibration of a laser level. We recommend that you check the calibration of your laser after it has been shipped, or if it has taken a drop or an impact. The following procedure will work with any rotating laser level.

1. Checking the calibration of the laser is the responsibility of the contractor. This is a simple procedure that takes about 10-15 minutes. The only equipment needed are a flat head tripod, the laser and detector, and a carpenter's level. This procedure will work with any laser.
2. Set the tripod up so that it is approximately 100 feet from a fixed object such as a wall or utility pole. Take the carpenter's level, and, using the tripod legs, level the head of the tripod as carefully as possible.
3. Attach the laser to the tripod and level it with the screws on the laser base, (L4, L4+, and L5 only). Servo leveled lasers such as the L1-AS and L6 will automatically level upon being turned on. If the tripod head has been properly leveled, it will be possible to rotate the laser 360° on the tripod with minimal re-leveling.
4. Rotate the laser so that the front is pointed at the target. On the L1-AS this will be the sloping part of the main housing. On the L4, L4+, or L5 this will be the side with the control panel.
5. Turn the laser on, then go to the target with the detector. Remove the clamp. When the detector gives the on grade signal, make a mark on the target using the detector's marking notch. Label this mark +Y.
6. Go back and rotate the laser 180° so that the back side of the laser is pointed at the target. This will be the side with the battery cover. Make sure that the laser is still level. Make a level mark with the detector, just as before. Label this mark -Y. The mid point between the -Y and +Y marks is true level. If the specified accuracy of the laser is ±1/8th inch, neither the -Y or +Y marks should be more than 1/8th inch from the mid point. If the specified accuracy of the laser is ±1/16th inch, neither the -Y or +Y marks should be more than 1/16th inch from the mid point.
7. Rotate the laser 90º the third side of the instrument is pointed at the target. Make sure the laser is level. With the detector, mark level on the target. Label this mark +X. The distance between this mark and true level should be within the specified accuracy of the laser. If the laser needs calibration refer to the full calibration procedure in the operator's manual, or take the instrument to an authorized service center.