PPB Concentration Calculator

About this calculator

Parts per billion (ppb) expresses an even more dilute concentration than ppm, calculated as ppb = (mass of solute / mass of solution) × 10⁹ — one ppb is a thousand times more dilute than one ppm, and equals 0.0000001%. This unit exists because many trace substances are meaningfully present, or regulated, at concentrations too small to express usefully in ppm or percentage.

Environmental scientists and water utilities use ppb to measure trace contaminants like heavy metals, pesticide residues, or emerging pollutants in drinking water and wastewater, since regulatory limits (such as EPA maximum contaminant levels) are often set in the ppb range. Toxicologists and analytical chemists doing ultra-trace analysis, and regulatory compliance officers verifying a facility meets discharge or emission limits, also rely on ppb as their standard working unit.