AQI Calculator
Enter your pollutant readings and see the Indian National Air Quality Index, the dominant pollutant and what it means for your health.
Your result will appear here
Enter at least PM2.5 and PM10, then press Calculate. Adding NO₂, SO₂, CO or O₃ makes the result more complete.
How the CPCB AQI works
The Air Quality Index (AQI) is based on the concentration of pollutants in the air, such as PM2.5 and PM10 (fine and coarse dust particles), NO2, SO2, CO and O3. The Central Pollution Control Board (CPCB) turns each pollutant's measured concentration into a sub-index, and the highest sub-index becomes the AQI that is reported. The result is a number from 0 to 500, and a higher number means more polluted air.
The CPCB groups the AQI into six categories:
- Good (0-50)
- Satisfactory (51-100)
- Moderate (101-200)
- Poor (201-300)
- Very Poor (301-400)
- Severe (401-500)
Calculated values come from sensor readings. An outdoor air quality monitor measures the air in a city or on a site, and an indoor air quality monitor tracks PM2.5 and other readings inside offices, schools and homes.
AQI calculator FAQ
What is AQI?
AQI stands for Air Quality Index. It is a single number that tells you how clean or polluted the air is and what that may mean for your health. Lower numbers mean cleaner air.
How is AQI calculated in India?
India uses the National Air Quality Index set by the CPCB. Each pollutant's concentration is converted into a sub-index using fixed breakpoints, and the highest sub-index is the overall AQI. This calculator needs your PM2.5 and PM10 readings, and the other four pollutants are optional.
What is a good AQI value?
An AQI of 0 to 50 is rated Good, and 51 to 100 is Satisfactory. Values from 101 upwards are Moderate, Poor, Very Poor or Severe, and the higher the number, the more people are affected. At Very Poor and Severe levels everyone should limit time outdoors.
How AQI is calculated
The Indian National AQI, set by the Central Pollution Control Board (CPCB), turns the concentration of each pollutant into a number between 0 and 500. Each pollutant gets its own sub-index. The worst sub-index is the overall AQI, and the pollutant behind it is called the dominant pollutant.
Between two breakpoints the sub-index rises in a straight line:
Sub-index = (IHi − ILo) ÷ (BPHi − BPLo) × (concentration − BPLo) + ILo
BPLo and BPHi are the lower and upper concentration of the band your reading falls in, and ILo and IHi are the index values of that band. For example, a PM2.5 reading of 45 µg/m³ falls in the 31 to 60 band (index 51 to 100) and gives a sub-index of 75.
Indian AQI categories
- Good 0 to 50
- Satisfactory 51 to 100
- Moderate 101 to 200
- Poor 201 to 300
- Very poor 301 to 400
- Severe 401 to 500
Breakpoints used by this calculator
| Category (index) | PM2.5 µg/m³ |
PM10 µg/m³ |
NO₂ µg/m³ |
SO₂ µg/m³ |
CO mg/m³ |
O₃ µg/m³ |
|---|---|---|---|---|---|---|
| Good (0–50) | 0 to 30 | 0 to 50 | 0 to 40 | 0 to 40 | 0 to 1 | 0 to 50 |
| Satisfactory (51–100) | 31 to 60 | 51 to 100 | 41 to 80 | 41 to 80 | 1.1 to 2 | 51 to 100 |
| Moderate (101–200) | 61 to 90 | 101 to 250 | 81 to 180 | 81 to 380 | 2.1 to 10 | 101 to 168 |
| Poor (201–300) | 91 to 120 | 251 to 350 | 181 to 280 | 381 to 800 | 10.1 to 17 | 169 to 208 |
| Very poor (301–400) | 121 to 250 | 351 to 430 | 281 to 400 | 801 to 1600 | 17.1 to 34 | 209 to 748 |
| Severe (401–500) | above 250 | above 430 | above 400 | above 1600 | above 34 | above 748 |
Source: CPCB, National Air Quality Index. PM2.5, PM10, NO₂ and SO₂ are 24-hour averages; CO and O₃ are 8-hour averages. The CPCB also covers NH₃ and lead, which this calculator does not.
Why this is not the same as the AQI on the map
The Live AQI map shows the US AQI, because that is the scale the free Open-Meteo data service provides. The US and Indian scales use different breakpoints, so the same air can give different numbers on each. Use this calculator when you want the Indian National AQI.