Milligrams per Liter (mg/L) is equivalent to which measurement?

Milligrams per Liter (mg/L) is equivalent to Parts Per Million (PPM) because both measurements represent the same concentration level in water. Specifically, 1 mg/L means there is 1 milligram of substance in one liter of water, which is effectively the same as saying there are 1 million parts of that substance in 1 million parts of water. This relationship is foundational in chemistry and environmental science, especially when evaluating water quality.

Other choices represent different scales of measurement. Parts Per Billion (PPB) would be a smaller scale, where 1 ppb is equal to 0.001 mg/L. Grams per Liter (g/L) is a larger measurement scale, where 1 g/L equals 1000 mg/L. Micrograms per Liter (ug/L) translates to parts per billion, with 1 ug/L equal to 0.001 mg/L, which further emphasizes the difference in measurement granularity.