In order to figure out how fast your granular product comes out, weigh out an amount of product to cover a specific size test area. We suggest a 200 sq ft test area. This will give you 1/5 of a 1,000 sq ft (most labels will provide you a quantity in lbs per 1,000 square feet.) For example Bifen LP says to use 5 lbs per 1,000 sq feet.
In the Bifen LP example, you would use 1lb to cover 200 sq ft. To calibrate it, you would put 1 lb in the hopper of your spreader.
Calculate (measure by measurement tools or step it off) a 200 sq ft and mark it.
You walk with your pace with your spreader to get an effective width that it spreads the chemical. This may several trial runs to get effective width rate. For example, if you discover that 1 lb throws out 10 feet width you mark out 20 feet long. This is 10 x 20 feet to get 200 square feet.
Test is 10 x 20 with a full lb of granulated product in your hopper.
Push spreader 20 feet to evenly spread the product of 200 sq ft test area.
Increase the setting number if there is still product in the hopper.
If you you run out of product, decrease the setting number.
You may want to remember this setting with this particular product for future reference.