PPM Concentration Calculator
Parts per million converted to mg/L, percent, ppb, total mass and molarity.
Results
Concentration
250.0000
mg/L
Percentage
0.025000
%
Parts per billion
250,000
ppb
Mass
250.0000
g
Molarity
0.00249775
mol/L
What this tool does
Parts per million is the unit trace measurements live in, from drinking water limits to pool chemistry to air quality. One ppm is one milligram in a kilogram — about a pinch of salt in a bathtub. The total mass tells you how much substance a whole tank actually contains at that concentration.
Formula
ppm = mg of solute ÷ kg of solution (in water ≈ mg/L)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
pp | Parts per million | ppm |
v | Volume | L |
mm | Molar mass | g/mol |
ML | Concentration | mg/L |
PC | Percentage | % |
PB | Parts per billion | ppb |
MS | Mass | g |
MO | Molarity | mol/L |
Worked example
- Parts per million250 ppm
- Volume1000 L
- Molar mass100.09 g/mol
- Concentration250.0000 mg/L
- Percentage0.025000 %
- Parts per billion250,000 ppb
- Mass250.0000 g
- Molarity0.00249775 mol/L
Limitations
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.
- Density changes with temperature, moisture and composition. Use a value from the supplier's data sheet whenever precision matters.
Frequently asked questions
Is one ppm really the same as one mg per litre?
In dilute water solutions, near enough. It works because a litre of water weighs almost exactly a kilogram, so a milligram in a litre is a milligram in a million. In brine, in solvents or in anything whose density is far from 1.00 g/mL, the equivalence breaks down and you need the mass-based definition instead.