PPM Calculator (Parts per Million)
By Santaji GadepatilinUpdated October 27, 2026
Parts per million (ppm) expresses very small concentrations — dissolved salts in water, pollutants in air or trace elements in a sample. 1 ppm is about 1 mg per litre of water.
How to use the PPM calculator
Enter the mass of the substance and the mass of the sample. You get ppm, percent and ppb. For water, 1 kg ≈ 1 L, so mg/kg ≈ mg/L ≈ ppm.
PPM formula
ppm = msubstance ÷ msample × 10⁶
Worked example
50 mg of chlorine in 1 kg (1 L) of water:
ppm = 0.050 g ÷ 1,000 g × 10⁶ = 50 ppm = 0.005%
Typical values
| Example | Concentration |
|---|---|
| Drinking-water chlorine (typical) | 0.2–1 ppm |
| WHO drinking-water fluoride limit | 1.5 ppm |
| CO₂ in air | ~420 ppm |
| Sea-water salt | ~35,000 ppm |
ppm, mg/L and percent
| ppm | mg/L (in water) | Percent |
|---|---|---|
| 1 | 1 | 0.0001% |
| 10 | 10 | 0.001% |
| 100 | 100 | 0.01% |
| 500 | 500 | 0.05% |
| 1,000 | 1,000 | 0.1% |
| 5,000 | 5,000 | 0.5% |
| 10,000 | 10,000 | 1% |
For dilute water solutions, 1 ppm ≈ 1 mg/L because 1 L of water weighs about 1 kg.
Drinking water guidelines (WHO)
| Substance | Guideline value |
|---|---|
| Fluoride | 1.5 mg/L |
| Nitrate (as NO₃⁻) | 50 mg/L |
| Arsenic | 0.01 mg/L (10 ppb) |
| Lead | 0.01 mg/L (10 ppb) |
Local standards may be stricter. Many countries also set limits for total dissolved solids (TDS) for taste, often around 500–1,000 mg/L.
ppm in gases
In air, ppm is usually by volume (ppmv). Carbon dioxide in outdoor air is now above 420 ppm. Indoor CO₂ above about 1,000 ppm suggests poor ventilation.
Dosing chlorine
To dose a 10,000 L tank to 2 ppm free chlorine with 10% sodium hypochlorite: chlorine needed = 10,000 × 2 = 20,000 mg = 20 g, so about 200 mL of 10% solution (assuming a density close to 1 g/mL; real bleach is slightly denser).
Conversions
1% = 10,000 ppm · 1 ppm = 1,000 ppb · 1 ppm = 1 mg/kg
Frequently asked questions
What does ppm mean?
Parts per million — 1 part of a substance in 1,000,000 parts of the whole. 1 ppm = 0.0001%.
Is ppm the same as mg/L?
For dilute water solutions, yes — 1 litre of water weighs about 1 kg, so 1 mg/L ≈ 1 ppm.
How do I convert ppm to percent?
Divide by 10,000. 5,000 ppm = 0.5%.
How many ppm is 1%?
10,000 ppm.
Is ppm the same as mg/L?
For dilute water solutions, yes, approximately. For other solvents or concentrated solutions, convert using density.