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Concentration shows up in ppm (parts per million), percent, ppb (parts per billion), and mg/L depending on the field — water quality reports typically use mg/L, while lab and lab-safety contexts often use ppm. This tool converts between all four.
How it works
ppm, percent, and ppb are pure ratios and always convert exactly: 1% = 10,000 ppm, and 1 ppm = 1,000 ppb. The mg/L conversion assumes a water-based solution with density ≈ 1 kg/L — the standard water-quality convention where 1 ppm ≈ 1 mg/L. For a denser solution or a different solvent, the true mg/L figure would differ from the ppm value.
- Enter value.
- Enter from.
- Enter to.
- Click Calculate to see your results.
Examples
A water quality reading
A contaminant reading of 5 mg/L in a water sample is equivalent to approximately 5 ppm, using the standard water-density assumption.
Who should use it
- Converting a water quality report's mg/L reading into ppm.
- Converting a lab concentration between ppm, percent, and ppb.
Industry applications
- Water treatment and environmental testing
- Chemistry and laboratory work
- Agriculture (fertilizer/pesticide concentration)
Advantages
- Covers the four most commonly used concentration units.
- Explicitly states the water-density assumption behind the mg/L conversion.
Limitations
- The mg/L conversion is only exact for water-based solutions near 1 kg/L density.
Common mistakes to avoid
- Applying the ppm ≈ mg/L water-density shortcut to a non-water solution or a very concentrated/dense mixture, where it no longer holds.
Best practices
- For anything beyond a dilute aqueous solution, use the solution's actual density to convert mg/L to ppm rather than assuming the water shortcut applies.
Tips
- Whenever mg/L is involved, double check whether your solution is actually water-based — for anything else, the ppm ≈ mg/L shortcut won't hold exactly.