Home › Unit Converter › Length Length Converter — loading units… From ⊘ ⇄ To ⊘ Formula — Quick Reference — click row to apply UnitResultEquivalent 🧪 Concentration Converter 💧 Liquid / Aqueous 💨 Gas / Air Solution Density (g/mL) Default: water = 1.000 g/mL Molar Mass (g/mol) optional Required for mol/L ↔ other Temp (°C) & Pressure (atm) Vm = 24.45 L/mol @ 25°C, 1 atm ppm (mg/kg) mg/L mg/m³ ppb µg/m³ % w/w % w/v g/L g/m³ mol/L (M) mmol/L (mM) ppmv (gas) Liquid mode (water, ρ=1.000 g/mL): ppm = mg/L ÷ ρ