Concentration Converter
Convert between ppm, ppb, mg/L, g/L, percent, and molarity
Unit Converter
Enter a value and select units to convert
Common Concentration Examples
| Substance | Typical Concentration | Context |
|---|---|---|
| Chlorine in pool water | 1-3 ppm (mg/L) | Recommended disinfection range |
| CO₂ in atmosphere | ~425 ppm | Current global average (2024) |
| Blood alcohol (legal limit) | 0.08% BAC | US legal driving limit |
| Fluoride in tap water | 0.7 ppm (mg/L) | US recommended level |
| Dissolved oxygen in water | 6-14 mg/L | Healthy aquatic levels |
| Salt in seawater | ~35 g/L (3.5%) | Average ocean salinity |
| Caffeine in coffee | ~400-800 mg/L | Brewed drip coffee |
| Chlorine in drinking water | 0.2-4 ppm | EPA maximum 4 mg/L |
| Lead in drinking water (EPA limit) | 15 ppb | EPA action level |
Quick Reference: Concentration Unit Relationships
ppm and mg/L
1 ppm = 1 mg/L (for dilute aqueous solutions where density is approximately 1 g/mL)
ppm and ppb
1 ppm = 1,000 ppb. Parts per billion is used for very trace concentrations.
Percent and ppm
1% = 10,000 ppm. Percent (% w/v) means grams of solute per 100 mL of solution.
Molarity
mol/L = (mg/L) / (molecular weight in g/mol x 1000). Requires knowing the substance's molecular weight.
Frequently Asked Questions
Is ppm the same as mg/L?
For dilute aqueous solutions (water-based), ppm and mg/L are effectively the same because the density of dilute water solutions is approximately 1 g/mL. However, for non-aqueous solutions, gases, or concentrated solutions, the equivalence does not hold and you must account for the density of the solution.
What does ppb mean and when is it used?
PPB stands for parts per billion. It is used for extremely small concentrations, such as trace contaminants in drinking water (e.g., lead at 15 ppb), pollutants in air, or trace elements in soil. 1 ppm = 1,000 ppb.
How do I convert ppm to molarity?
To convert ppm (or mg/L) to molarity (mol/L), divide the ppm value by the substance's molecular weight in g/mol, then divide by 1000. Formula: Molarity = ppm / (MW x 1000). For example, 100 ppm NaCl (MW = 58.44) = 100 / (58.44 x 1000) = 0.00171 mol/L.
What is the difference between w/v% and v/v%?
W/v% (weight/volume percent) measures grams of solute per 100 mL of solution — used for solid solutes dissolved in liquids. V/v% (volume/volume percent) measures mL of solute per 100 mL of solution — used for liquid-liquid mixtures like alcohol in beverages. This converter uses w/v%.