Flow Hood CFM Calculator
Correct a balometer flow hood reading for its calibration factor.
Enter your values
ⓘ Live results
Results
- Corrected airflow
- 152.3 CFM
- Correction applied
- 5%
- Raw reading
- 145 CFM
Quick answer
Corrected CFM equals the flow hood's displayed reading multiplied by its calibration correction factor for that register type.
CFM_corrected = CFM_reading x K_factor
How to use the Flow Hood CFM Calculator
- 1Read the raw CFM shown on the flow hood display.
- 2Apply the manufacturer's correction factor for the specific diffuser or grille type (often 0.9-1.15).
- 3Use the corrected value for TAB (testing, adjusting, balancing) reports.
Worked example
Using the values the calculator loads with:
Inputs
- Flow hood reading145 CFM
- Correction factor (K)1.05
Results
- Corrected airflow152.3 CFM
- Correction applied5%
- Raw reading145 CFM
Frequently asked questions
Why is a correction needed?
Capture hoods disturb the natural flow pattern of some diffusers, causing a small but consistent reading error.
Where do I get K factors?
From the flow hood or diffuser manufacturer's published correction tables for each diffuser model.
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.