Re: Is there a difference between ppm and mg/l? If you are dealing with water (as most on this forum presumable do!), they are equivalent. The reason is that 1 liter of water weighs 1 kilogram. So, when you have 1 milligram of a substance dissolved in water (weight of 1,000 grams or 1,000,000 milligrams) it is the same as 1 part per million. For other liquids this does not work out so neatly because they have different weights. This is the beauty of the metric system. |