PPM to mg/m³ (CO₂) Calculator

How to Convert CO2 PPM to mg/m3

When performing a PPM to mg/m3 conversion, it is important to understand that Parts Per Million (PPM) is a volumetric ratio, while mg/m³ is a measure of mass concentration. This CO2 PPM to mg/m3 calculator uses the exact ideal gas law to determine the true CO2 mass concentration based on your specific environmental conditions. If you need to convert back to parts per million, you can use our reverse mg/m³ to PPM (CO₂) converter.

The Ideal Gas Law & Environmental Impact

If you want to know how to calculate CO2 mass concentration at 1 atm with custom temperatures, you must account for gas expansion. Because gases expand when heated, the molar volume of air changes based on the environment. For carbon dioxide, the carbon dioxide molecular weight (44.01 g/mol) remains constant, but the molar volume shifts:

• Standard temperature and pressure (STP): At 0°C and 1 atm, the molar volume is approximately 22.4 L/mol.
• Warm Environments: At 35°C, the gas expands, increasing the molar volume and effectively lowering the final mg/m³ for the same PPM reading.

Common CO2 Limits & Conversions (at 25°C, 1 atm)

Here are several critical baseline mass concentration values for Carbon Dioxide under standard OSHA environmental conditions:

Regulatory Standards (OSHA & NIOSH)

For industrial hygiene gas conversion and indoor air quality (IAQ) monitoring, precision is required for legal compliance across our environmental safety calculators suite. If you need an OSHA exposure limit ppm to mg/m3 calculator, you can use our built-in standard preset. The NIOSH REL CO2 conversion to mg/m3 and OSHA standards both legally mandate baseline testing at standard conditions of 25°C and 1 atm, which sets the molar volume at exactly 24.45 L/mol.