Radon Fan CFM Calculator
Sub-slab depressurisation fan sizing.
Enter your values
ⓘ Live results
Results
- Target airflow
- 60 CFM
- Suction range
- 0.5 - 1.0 in wc
- Suction pits suggested
- 1
- Pipe size
- 3 in PVC
Quick answer
Radon fans are sized by slab area and sub-slab material, with tighter gravel needing higher suction and less airflow.
CFM ≈ area x rate for sub-slab material
How to use the Radon Fan CFM Calculator
- 1Measure the slab footprint the system must cover.
- 2Identify the sub-slab material from a core sample or the builder's spec.
- 3Pick a fan whose curve delivers this CFM at the listed suction, then verify with a post-mitigation radon test.
Worked example
Using the values the calculator loads with:
Inputs
- Slab area1200 sq ft
- Sub-slab materialClean gravel
Results
- Target airflow60 CFM
- Suction range0.5 - 1.0 in wc
- Suction pits suggested1
- Pipe size3 in PVC
Frequently asked questions
Does more CFM always help?
No — tight soils need high suction at low flow; an oversized flow fan just wastes energy.
Where does the pipe discharge?
Above the roof line and away from windows, per EPA guidance.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.