Bedroom CFM Calculator
Supply airflow for a bedroom.
Enter your values
Enter the room area in sq ft.
Enter the ceiling height in ft.
Enter the airflow rate in CFM/sq ft.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Supply airflow
- 150 CFM
- Air changes
- 7.5
- Register size at 450 FPM
- 7.8 in equivalent
- Branch duct at 700 FPM
- 6.3 in dia
- Return path
- Undercut door or transfer grille
Quick answer
Bedrooms are typically supplied at about 1 CFM per square foot, or 4-5 air changes per hour.
CFM = area x 1 CFM per sq ft
At a glance
| What it does | Supply airflow for a bedroom. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Room area, Ceiling height, Airflow rate |
| Main output | Supply airflow |
| Formula | CFM = area x 1 CFM per sq ft |
| Cost | Free — no sign-up, no download |
How to use the Bedroom CFM Calculator
- 1Measure the bedroom floor area.
- 2Use 1 CFM per sq ft as a starting point, more for rooms with big west-facing glass.
- 3Give the room a return path so the door does not pressurise it.
Inputs explained
- Room area(sq ft)
- Enter the room area in sq ft.
- Ceiling height(ft)
- Enter the ceiling height in ft.
- Airflow rate(CFM/sq ft)
- Enter the airflow rate in CFM/sq ft.
Worked example
Using the values the calculator loads with:
Inputs
- Room area150 sq ft
- Ceiling height8 ft
- Airflow rate1 CFM/sq ft
Results
- Supply airflow150 CFM
- Air changes7.5
- Register size at 450 FPM7.8 in equivalent
- Branch duct at 700 FPM6.3 in dia
- Return pathUndercut door or transfer grille
Frequently asked questions
Why does a closed bedroom get stuffy?
Without a return path, supply air pressurises the room and airflow collapses.
Master bedroom?
Large or sun-exposed rooms often need 1.2-1.5 CFM per sq ft.
What do I need to enter into the Bedroom CFM Calculator?
Just 3 values: room area, ceiling height, airflow rate. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Bedroom CFM Calculator work out the answer?
Bedrooms are typically supplied at about 1 CFM per square foot, or 4-5 air changes per hour. It applies the formula CFM = area x 1 CFM per sq ft and shows the working so you can check each step by hand.
Is the Bedroom CFM Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.