Concentration Unit Converter

For dilute aqueous solutions, ppm (parts per million) and mg/L are essentially equivalent. 1 ppm = 1 mg/L when the solution density is approximately 1 g/mL, which is true for most water-based solutions at room temperature.

PPB (parts per billion) is 1000 times smaller than ppm (parts per million). To convert: ppm × 1000 = ppb, or ppb ÷ 1000 = ppm. For example, 5 ppm equals 5000 ppb.

Molecular weight is required when converting to or from molarity (M). Molarity is moles per liter, so you need the molecular weight to convert between mass-based units (like mg/L, ppm) and mole-based units (molarity).

Solution density is the mass of solution per unit volume, typically expressed in g/mL. It's needed for conversions involving weight percentage (%) because weight percentage is mass of solute per mass of solution, not per volume.

Yes, but you need to know the solution density. The conversion is: weight% × density × 10,000 = ppm. For example, 0.1% in water (density ≈ 1 g/mL) equals approximately 1000 ppm.

For aqueous solutions, μg/L (micrograms per liter) is approximately equal to ppb (parts per billion). This relationship holds when the solution density is close to 1 g/mL, which is typical for dilute water-based solutions.

The conversions are mathematically accurate, but real-world accuracy depends on the precision of your input values and the assumptions made (like solution density). For very concentrated solutions or non-aqueous solvents, additional factors may need consideration.

Environmental science commonly uses mg/L and μg/L; chemistry uses molarity (M) and weight percentage; water treatment uses ppm and ppb; air quality monitoring uses mg/m³ and μg/m³. The choice depends on the concentration range and application requirements.