Units used at MEL

Lab results are usually reported as densities - the amount of some element per unit of sample.

Not all labs use the same units in reporting results for the same tests. This page will help you compare test results if different units have been used.


mg/L= 1 ppm (part per million) = 1 milligram of element per liter of liquid

μg/L = 1 ppb (part per billion) = 1 micrograms of element per liter of liquid


mg/L ÷ 1000 = μg/L

μg/L x 1000 = mg/L


mg/kg = 1 ppm (part per million)= 1 milligram of element per kilogram of material

μg/kg = 1 ppb (part per billion)= 1 microgram of element per kilogram of material


mg/kg ÷ 1000 = μg/kg

μg/kg x 1000 = mg/kg



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Units of Measurement


g- a gram is about as much mass as a paper clip

kg - a kilogram = 1000 grams = about 2.2 pounds

mg - a milligram = 1/1000 of a gram

μg- a microgram = 1/1,000,000 of a gram*


L - a liter is about 4 cups of liquid.

mL - a milliliter = 1/1000 of a liter.


* "μ" is the symbol for "micro" or "1/million."

It may appear in lab reports as a simple "u", as in ug/kg.