ppm is a value that represents the concentration of one part per million parts (1/1,000,000) of something in water or soil. One ppm is equivalent to 1 milligram of something per liter of water or 1 milligram of something per kilogram of soil.
Formula:
PPM = (Defective Parts / Total Parts) × 1,000,000
Defective Rate = (Defective Parts / Total Parts)
Defective Rate (%) = (Defective Parts / Total Parts) × 100