Parts per million (ppm) is a way of expressing very small (trace) concentrations — for a dilute water-based solution, 1 ppm is approximately equal to 1 milligram of solute per liter of solution.
Parts per million (ppm) is a way of expressing very small (trace) concentrations — for a dilute water-based solution, 1 ppm is approximately equal to 1 milligram of solute per liter of solution. This calculator finds ppm using the common convention of milligrams of solute per kilogram of solution.
A water sample contains 5 mg of a contaminant in 10 kg of water. Concentration = 5 / 10 = 0.5 ppm.
Parts per million, a way of expressing very dilute concentrations, scaled by a million instead of a hundred.
ppm = (mass or volume of solute ÷ mass or volume of total solution) × 1,000,000.
Percentage becomes awkward with tiny numbers, while ppm keeps the numbers in a more readable range.