Why concentration units differ
Concentration units describe how much of one substance exists inside a larger mixture, but different fields use different measurement bases.
Water quality often uses mg/L and PPM. Air quality may use PPM, mg/m³, or µg/m³. Manufacturing quality uses PPM to describe defects per million units.
Common unit relationships
One percent equals 10,000 PPM. One PPM equals 1,000 PPB. For dilute water, 1 mg/L is often approximately 1 PPM.
Gas conversions are different because PPM is usually a volume ratio, while mg/m³ and µg/m³ are mass concentrations.
Choosing the right calculator
Start with the unit you already have, then choose the calculator that converts to the unit required by your report, meter, label, or workflow.
- Use percent calculators for percent concentration labels.
- Use mg/L calculators for dilute water reports.
- Use gas calculators when molar mass and conditions matter.
Frequently asked questions
What is the most common PPM conversion?
PPM to percent, percent to PPM, PPM to mg/L, and mg/L to PPM are among the most common.
Why are gas concentration units harder?
Gas conversions need molar mass, temperature, and pressure because mass per volume changes with conditions.