RV Vent Fan CFM Calculator
Roof vent fan size for an RV or van.
Enter your values
ⓘ Live results
Results
- Fan airflow
- 324 CFM
- Interior volume
- 432 cu ft
- Intake opening needed
- 1.08 sq ft
- Cooking boost (60 ACH)
- 432 CFM
- Power draw estimate
- 16.2 W
Quick answer
A camper interior is small, so most van builds target 30-60 air changes per hour for effective cooling.
CFM = interior volume x ACH / 60
How to use the RV Vent Fan CFM Calculator
- 1Measure the usable interior box dimensions.
- 2Pick 30-45 ACH for comfort, more if you cook inside a lot.
- 3Crack a window or fit a floor vent so the fan has intake air.
Worked example
Using the values the calculator loads with:
Inputs
- Interior length12 ft
- Interior width6 ft
- Interior height6 ft
- Air changes45 ACH
Results
- Fan airflow324 CFM
- Interior volume432 cu ft
- Intake opening needed1.08 sq ft
- Cooking boost (60 ACH)432 CFM
- Power draw estimate16.2 W
Frequently asked questions
One fan or two?
Two fans, one intake and one exhaust, cross-ventilate far better than a single unit.
Battery drain?
Most 12V roof fans use 1-3 amps, so overnight running is easy on a modest battery bank.
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.