Free Air Quality Tools & Calculators
Take control of your indoor air quality with our free calculators and tools. Whether you're interpreting CO2 readings, sizing an air purifier, or understanding how air quality affects your health, these tools give you the data you need.
CO2 Level Interpreter
Enter your CO2 reading and get instant color-coded feedback, health recommendations, and see how your air compares to common environments.
Use this toolRoom Ventilation Calculator
Calculate required air changes per hour and ventilation rates based on room size, occupancy, and activity level. See CO2 decay projections.
Use this toolAir Purifier Sizing Calculator
Find the right CADR rating and purifier size for your room. Get personalized recommendations based on your air quality concerns.
Use this toolAir Quality Index Calculator
Convert PM2.5 concentration to AQI using the official EPA formula. Get color-coded health guidance and WHO guideline comparisons.
Use this toolMonitor Comparison Tool
Compare 2-3 CO2 monitors side by side on price, sensors, connectivity, accuracy, and features. Find the best monitor for your needs.
Use this toolHealth Impact Calculator
Estimate how indoor CO2 levels affect your cognitive performance and health, based on Harvard COGFX study data.
Use this toolCalculators Estimate — Monitors Measure
Every tool here models your air from inputs. A monitor tells you what it actually is.
Aranet Aranet4 Home
$200NDIR sensor · ±50 ppm · Built-in display
Research-grade ±50 ppm accuracy and runs 2+ years on a charge.
AirGradient ONE
$150NDIR sensor · ±50 ppm · Built-in display
Research-grade ±50 ppm accuracy and tracks 6 metrics in one unit.
Airthings View Plus
$300NDIR sensor · ±50 ppm · Built-in display
Research-grade ±50 ppm accuracy and tracks 7 metrics in one unit.
See our full home monitor rankings →
Prices are typical street prices and change often. We earn a commission on purchases made through these links, at no extra cost to you.
Why Use Our Air Quality Calculators?
Science-Based Calculations
Our tools use peer-reviewed research, EPA formulas, and ASHRAE ventilation standards to give you accurate, actionable results.
Protect Your Health
Indoor air quality directly impacts cognitive performance, sleep quality, and long-term health. Understanding your air is the first step to improving it.
Make Informed Purchases
Our comparison and sizing tools help you avoid buying the wrong monitor or purifier, saving you money and ensuring effective air quality management.
100% Free
All tools are free to use with no sign-up required. Bookmark them and come back anytime you need air quality guidance.