PM2.5 AQI Calculator
Enter a 24-hour average PM2.5 concentration in µg/m³. The calculator truncates it to one decimal place, then applies the cited US EPA breakpoints.
For a 24-hour average only. Not a live, location-based or complete AQI; not health advice.
- PM2.5 AQI sub-index
- Category
A QUICK WALKTHROUGH
How to use this tool
- Enter a 24-hour average PM2.5 concentration in µg/m³.
- Calculate the US EPA PM2.5 sub-index.
- Read the category and method limits.
Method and breakpoint version
This calculator uses the US EPA PM2.5 24-hour breakpoints published in the EPA AQI table as checked on 2026-10-09, including the Good band of 0.0–9.0 µg/m³. It truncates concentration to one decimal place, interpolates between the corresponding concentration and AQI breakpoints, then rounds the index to the nearest integer. The supported concentration range ends at 325.4 µg/m³ (AQI 500).
Scope
This is a manually entered 24-hour PM2.5 sub-index only. It is not a location lookup, live or NowCast AQI, a complete multi-pollutant AQI, a forecast, or health advice. It does not account for other pollutants.
Source
US EPA, How the AQI is calculated and current AQI breakpoints: https://www.epa.gov/outdoor-air-quality-data/how-aqi-calculated · https://aqs.epa.gov/aqsweb/documents/codetables/aqi_breakpoints.html
GOOD TO KNOW
Common questions
Can I enter a live sensor reading?
Only if it represents the required 24-hour average concentration. An instantaneous reading is not equivalent.
Is this the AQI for my location?
No. It calculates a PM2.5 sub-index from the value you enter and does not retrieve location or live data.