Free Air Quality Calculators
Quick, free calculators for the questions people ask before buying an air purifier or humidifier.
Each calculator runs in your browser, needs no sign-up and shows the formula it uses, so you can check the result yourself.
- Air purifier size calculator: enter your room size and ceiling height to get the minimum CADR you need, or check how many air changes per hour a specific purifier delivers.
- Air purifier electricity cost calculator: see what running a purifier costs per day, month and year, including replacement filters.
- Dew point calculator: find the dew point for any temperature and humidity, and check whether a window or wall will collect condensation.
Not sure what to buy yet? Start with where to put an air purifier or our guide to the ideal indoor humidity.
In this section
Free tool
Air Purifier Electricity Cost Calculator: What Does It Cost to Run?
Enter the watts, hours of use and your electricity rate to see what an air purifier costs per day, month and year, including replacement filters.
Free calculator
Free tool
Air Purifier Size Calculator: What CADR Do You Need?
Enter your room size and ceiling height to get the minimum CADR you need, or check how many air changes per hour a specific purifier delivers.
Free calculator
Free tool
Dew Point Calculator: Will Your Windows Fog Up?
Enter the temperature and relative humidity to get the dew point, then check whether a window, wall or pipe will collect condensation.
Free calculator