High-Wall Register Size Calculator
Size a high sidewall supply register.
Enter your values
ⓘ Live results
Results
- Required free area
- 0.217 sq ft
- Gross opening size
- 0.289 sq ft
- Approx size
- 6.4 x 6.4 in
- Suggested throw check
- Aim for throw ≈ 3/4 of room width
Quick answer
High sidewall registers are commonly designed for 500-700 FPM face velocity since throw across the ceiling plane matters more than at floor level.
Free area = CFM / face velocity
How to use the High-Wall Register Size Calculator
- 1Enter the register's design CFM.
- 2Use 500-700 FPM, higher than floor registers, since the jet needs to travel and mix near the ceiling.
- 3Verify the resulting throw with the register throw calculator.
Worked example
Using the values the calculator loads with:
Inputs
- Register CFM130 CFM
- Face velocity600 FPM
- Free area fraction75 %
Results
- Required free area0.217 sq ft
- Gross opening size0.289 sq ft
- Approx size6.4 x 6.4 in
- Suggested throw checkAim for throw ≈ 3/4 of room width
Frequently asked questions
Why higher velocity than floor registers?
High sidewall registers rely on the Coanda effect along the ceiling for mixing, needing more velocity to carry that far.
Floor or high sidewall — which is better?
It depends on climate and duct routing; high sidewall suits cooling-dominant climates, floor suits heating-dominant ones.
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.