Gas Concentration Converter

Q: 1. What is the difference between PPM and mg/m³?

PPM (Parts Per Million) is a measurement of volume-to-volume ratio. It tells you how many "gas particles" are in the air relative to air particles. It does not change with temperature. mg/m³ (Milligrams per cubic meter) is a measurement of mass-to-volume. It tells you the physical weight of the contaminant. This does change as the gas expands or contracts.

Q: 3. How much is 1 PPM in PPB?

1 PPM=1000 PPB. Example: 5 PPM = 5,000 PPB

Understanding gas concentration units is critical in chemical plants, safety audits, environmental monitoring, and laboratory work. Different standards and reports use different units like PPM to PPB, mg/L to PPM, mg/m³, or percentage, which often leads to confusion.

To make this simple, we’ve built this Gas Concentration Converter added to chemical engineering calculator list, that lets you convert values accurately under both general conditions and real industrial operating conditions, including temperature and pressure effects.

Convert PPM to mg/m³, mg/L, and % (With OSHA Limits)

Concentration (PPM)

mg/L (Water/Liquid)

Parts Per Billion (PPB)

Percentage (%)

PPM → mg/m³ mg/m³ → PPM

Select Chemical / Gas

Custom Molecular Weight (g/mol)

Concentration (PPM)

Temperature (°C)

Pressure

Calculated Result

0.000 mg/m³

Mode 1: Simple (Water & Liquids) ppm to ppb converter

Use this tab for water treatment, pool chemistry, or laboratory solutions.

mg/L to PPM Converter or PPM to PPB.
The Logic: For dilute aqueous solutions, the density of water is approximately 1kg/L. Therefore, 1mg/L ≈1PPM.

Mode 2: Industrial Gas (Engineering)

Use this tab for air quality monitoring, industrial hygiene, and sensor calibration.

Best for: Converting mg/m³ to PPM for gases like Ammonia, Benzene, or Chlorine.
The Logic: Gases expand with heat and compress with pressure. Our tool uses the Ideal Gas Law (PV=nRT) to adjust the concentration based on your specific environmental conditions.

What does this Gas Concentration Converter do?

This calculator helps you for the following conversions

Convert PPM to mg/m³ and mg/m³ to PPM for gases
Convert PPM ↔ PPB ↔ mg/L ↔ % for dilute aqueous solutions
Apply temperature and pressure correction using the ideal gas law
Compare results with OSHA exposure limits for common industrial gases
Quickly assess whether a concentration is safe, cautionary, or hazardous

Engineers make the mistake of using a simple “times 1000” conversion for gases. This is dangerous because it ignores the physical properties of the gas.

A gas sensor reading 50 PPM of Ammonia in a cold storage room (-10 deg C) represents a completely different mass of gas than the same 50 PPM reading in a hot boiler room (40 deg C).

Conversion Formulas (mg/L to PPM converter

For Liquids (mg/L ↔ PPM)

$1 \text{ PPM} = 1 \text{ mg/L}$

(Note: This assumes the solvent is water with a density of 1.0 g/mL. For denser liquids like Sulfuric Acid, this 1:1 ratio does not apply.)

2. For Gases (mg/m³ ↔ PPM)

To convert volumetric concentration (PPM) to gravimetric concentration (mg/m³), we must calculate the Molar Volume ( $V_m$ ) of the gas at the measured temperature and pressure.

$\mathrm{mg/m^3} = \frac{\mathrm{PPM} \times \mathrm{Molecular\ Weight\ (MW)}}{V_m}$

$V_m = \frac{R \times T}{P}$

R: Ideal Gas Constant (0.082057 L·atm·K⁻¹·mol⁻¹)
T: Temperature in Kelvin (℃ + 273.15)
P: Pressure in Atmospheres (atm)

Example 1 : Determining Chlorine PPM to mg/L

A wastewater treatment technician measures a residual Chlorine concentration of 2.5 mg/L in a final effluent sample. Express this concentration in Parts Per Million (PPM) and Parts Per Billion (PPB).

For dilute solutions where water is the primary solvent, the conversion factor is 1:1 because 1 Liter of water weighs 1 Kilogram.

1 mg/L ≈ 1 mg/kg = 1PPM

Hence 2.5mg/L = 2.5 PPM

To convert to PPM to PPB,

2.5PPM X 1000 =2,500 PPB

Answer: The concentration is 2.5 PPM or 2,500 PPB.

Example 2 : How to Convert PPM to mg/m³

An industrial sensor detects Ammonia (NH₃) at a concentration of 50 PPM inside a process plant. The temperature is 40°C and a standard pressure of 1 atm. Calculate the gravimetric concentration in mg/m³

Convert Temperature to Kelvin T(K) = 40 + 273.15 = 313.15 K

Calculate Molar Volume

$V_m = \frac{R \times T}{P}$

$V_m = \frac{0.082057 \times 313.15}{1} = \mathbf{25.69 \text{ L/mol}}$

Calculate Final Concentration

$\text{mg/m}^3 = \frac{\text{PPM} \times MW}{V_m}$

$\text{mg/m}^3 = \frac{50 \times 17.03}{25.69}$

$\text{mg/m}^3 = \frac{851.5}{25.69} = \mathbf{33.14 \text{ mg/m}^3}$

The concentration of Ammonia is 33.14 mg/m³

FAQ

1. What is the difference between PPM and mg/m³?

PPM (Parts Per Million) is a measurement of volume-to-volume ratio. It tells you how many “gas particles” are in the air relative to air particles. It does not change with temperature. mg/m³ (Milligrams per cubic meter) is a measurement of mass-to-volume. It tells you the physical weight of the contaminant. This does change as the gas expands or contracts.

2. How do I convert PPM to Percentage (%)?

The conversion factor is 10,000. 1%=10,000 PPM

3. How much is 1 PPM in PPB?

1 PPM=1000 PPB. Example: 5 PPM = 5,000 PPB

4. How to convert PPB to PPM?

To convert from Parts Per Billion to Parts Per Million, you divide by 1,000