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US-EPA Air Quality Index from PM₂.₅ Calculator

Piecewise-linear AQI from PM₂.₅ in µg/m³ (24-h avg).

Compute the US-EPA Air Quality Index (AQI) from a 24-hour average PM₂.₅ concentration in µg/m³. Uses the official piecewise-linear breakpoint table (Good 0-50, Moderate 51-100, USG 101-150, Unhealthy 151-200, Very Unhealthy 201-300, Hazardous 301-500).

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

µg/m³

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

AQI = (I_hi − I_lo) / (BP_hi − BP_lo) · (PM − BP_lo) + I_lo (per band).

In depth

Compute the US-EPA Air Quality Index (AQI) from a 24-hour average PM₂.₅ concentration in µg/m³. Uses the official piecewise-linear breakpoint table (Good 0-50, Moderate 51-100, USG 101-150, Unhealthy 151-200, Very Unhealthy 201-300, Hazardous 301-500).