Single Pass Method 

Calibration Steps 
Sample Problem 
1. Set the gate openings on your spreader using the product label directions; or set them so that they are slightly larger than the granules. Read the label recommended rate of application.

Gate setting – 5 ¾ Label rate – 20 lb/ 5,000 ft^{2 } or 4 lb / 1,000 ft^{2} 
2. Measure the width of the bottom of the hopper between the wheels.

Length – 24 in 
3. Convert the inches in Step 2 to feet by dividing by 12

Length – 2 ft 
4. Measure and mark a convenient distance on clean pavement such as a driveway; fifty feet is suggested. Ten passes back and forth along this distance will result in the release of enough product, to calibrate the equipment accurately.

50 ft x 10 passes = 500 ft 
5. Compute the area covered by multiplying the length of the hopper
(Step 3) times the length of the area (Step 4). 
2 ft x 500ft^{2}= 1,000 ft^{2} 
6. Weigh the amount of product that you use to fill the hopper. Turn the spreader on and push it over the test strip ten times, using a consistent walking speed. Be sure to turn the spreader off, immediately, when you reach the end of the test strip

Put 5 lb of product in the hopper 
7. Weigh the amount of product that is left in the hopper.

1 lb left in hopper 
8. Compute the amount of product that was used to cover the test area by subtracting the leftover amount (Step 7) from the amount put into the hopper (Step 6). The result represents the amount of product applied to the 1,000 squarefoot test area.

5 lb – 1lb = 4 lb / 1,000 ft^{2} 
9. If the amount of the product used (Step 8) is within 10 percent (high or low) of the labelrecommended rate (Step 1), the spreader is calibrated correctly. If the amount of product is not between 90 and 110 percent of the labeled rate, (that is, if it is not within ±10 percent), reset the gate openings and repeat the process.

In this case, 4 lb per 1,000 ft^{2 }equals the label rate of 20 lb per 5,000 ft^{2}. So no additional adjustments are necessary. 
10. Determine the area to be treated by multiplying its length times its width and subtracting the square footage of areas that will not be to be treated.

From option 1, the total area to be treated id 6,300ft^{2} 
11. Apply the product according to label directions, using the gate setting determined in calibrating the spreader.

6,300ft^{2 }÷ 5,000 ft^{2} per bag = 1.26 bags 