Convert mol/L, mmol/L, or µmol/L to ppm, mg/L, or µg/L using molecular weight, or solve for concentration or molecular weight from any two values.
| mol/L to ppm | ppm to mol/L |
|---|---|
| 0.000001 mol/L = 0.05844 ppm | 1 ppm = 0.00001711 mol/L |
| 0.00001 mol/L = 0.5844 ppm | 5 ppm = 0.00008557 mol/L |
| 0.0001 mol/L = 5.844 ppm | 10 ppm = 0.0001711 mol/L |
| 0.00025 mol/L = 14.61 ppm | 25 ppm = 0.0004278 mol/L |
| 0.0005 mol/L = 29.22 ppm | 50 ppm = 0.0008557 mol/L |
| 0.001 mol/L = 58.44 ppm | 100 ppm = 0.001711 mol/L |
| 0.002 mol/L = 116.88 ppm | 250 ppm = 0.004278 mol/L |
| 0.005 mol/L = 292.2 ppm | 500 ppm = 0.008557 mol/L |
| 0.01 mol/L = 584.4 ppm | 750 ppm = 0.01284 mol/L |
| 0.1 mol/L = 5,844 ppm | 1,000 ppm = 0.01711 mol/L |
| Formulas: ppm (mg/L) = (mol/L) × MW × 1000; mol/L = ppm ÷ (MW × 1000). Assumes MW = 58.44 g/mol. | |
| mol/L to ppm | ppm to mol/L |
|---|---|
| 0.000001 mol/L = 0.18016 ppm | 1 ppm = 0.000005551 mol/L |
| 0.00001 mol/L = 1.8016 ppm | 5 ppm = 0.00002776 mol/L |
| 0.0001 mol/L = 18.016 ppm | 10 ppm = 0.00005551 mol/L |
| 0.00025 mol/L = 45.04 ppm | 25 ppm = 0.0001388 mol/L |
| 0.0005 mol/L = 90.08 ppm | 50 ppm = 0.0002776 mol/L |
| 0.001 mol/L = 180.16 ppm | 100 ppm = 0.0005551 mol/L |
| 0.002 mol/L = 360.32 ppm | 250 ppm = 0.001388 mol/L |
| 0.005 mol/L = 900.8 ppm | 500 ppm = 0.002776 mol/L |
| 0.01 mol/L = 1,801.6 ppm | 750 ppm = 0.004163 mol/L |
| 0.1 mol/L = 18,016 ppm | 1,000 ppm = 0.005551 mol/L |
| Formulas: ppm (mg/L) = (mol/L) × MW × 1000; mol/L = ppm ÷ (MW × 1000). Assumes MW = 180.16 g/mol. | |
mol/L to PPM Formula
Mass ppm means mg of solute per kg of solution. First calculate mg/L as mol/L × molar mass × 1000, then divide by actual solution density in kg/L (numerically equal to g/mL). The mg/L and mass-ppm values are approximately equal only when solution density is approximately 1 kg/L. The conversion tables use that stated approximation.
Molar Mass of Common Substances
Molar mass must match the exact reported analyte and chemical form; actual solution density is also needed for mass ppm unless the dilute-water approximation applies. Values for frequently converted compounds:
| Substance | Formula | Molar Mass (g/mol) | Common Use Context |
|---|---|---|---|
| Water | H₂O | 18.015 | Solvent baseline |
| Sodium chloride | NaCl | 58.44 | Salinity, saline solutions |
| Glucose | C₆H₁₂O₆ | 180.16 | Blood glucose, cell culture media |
| Ethanol | C₂H₅OH | 46.07 | Solvents, fermentation monitoring |
| Calcium carbonate | CaCO₃ | 100.09 | Water hardness (as CaCO₃) |
| Nitrate ion | NO₃⁻ | 62.00 | Fertilizer runoff, drinking water |
| Nitrite ion | NO₂⁻ | 46.01 | Cured meats, wastewater |
| Phosphate ion | PO₄³⁻ | 94.97 | Eutrophication, wastewater treatment |
| Copper(II) sulfate | CuSO₄ | 159.61 | Algicide, micronutrient dosing |
| Sodium bicarbonate | NaHCO₃ | 84.01 | pH buffering |
| Potassium permanganate | KMnO₄ | 158.03 | Water treatment oxidant |
| Arsenic | As | 74.92 | Groundwater contamination |
| Lead | Pb | 207.2 | Pipe corrosion, legacy contamination |
| Fluoride ion | F⁻ | 19.00 | Drinking water fluoridation |
| Mercury | Hg | 200.59 | Industrial effluent monitoring |
EPA Drinking Water Limits: ppm and Molar Equivalents
EPA values below are mass-per-volume limits or action levels. mg/L only approximates mass ppm near a solution density of 1 kg/L. Match the reporting basis: nitrate and nitrite limits are measured as nitrogen. These arithmetic equivalents do not establish compliance or give laboratory preparation instructions.
| Contaminant | MCL/action level (mg/L) | Molar Mass (g/mol) | MCL (mol/L) |
|---|---|---|---|
| Nitrate (as nitrogen) | 10 | 14.01 (N) | 7.14 × 10⁻⁴ |
| Fluoride (F⁻) | 4.0 | 19.00 | 2.11 × 10⁻⁴ |
| Copper (Cu) | 1.3 * | 63.55 | 2.05 × 10⁻⁵ |
| Nitrite (as nitrogen) | 1.0 | 14.01 (N) | 7.14 × 10⁻⁵ |
| Selenium (Se) | 0.05 | 78.96 | 6.33 × 10⁻⁷ |
| Arsenic (As) | 0.010 | 74.92 | 1.34 × 10⁻⁷ |
| Lead (Pb) | 0.015 * | 207.2 | 7.24 × 10⁻⁸ |
| Mercury (Hg) | 0.002 | 200.59 | 9.97 × 10⁻¹⁰ |
| Source: EPA National Primary Drinking Water Regulations, checked October 20, 2026. * Denotes action level, not MCL. Lead 0.015 mg/L is the current action level; the revised 0.010 mg/L begins November 1, 2027. Formula: mol/L = mg/L ÷ (reported-analyte molar mass × 1000). Nitrate and nitrite molar equivalents use nitrogen mass (one N per ion). | |||
