Case Fan Airflow Calculator
Calculate case airflow, air changes and the temperature rise it permits.
About Case Fan Airflow Calculator
Airflow removes heat in proportion to mass flow, so doubling airflow halves the temperature rise. Intake filters cost far more airflow than exhaust paths, which is why intake and exhaust are derated differently. Positive pressure means all incoming air passes a filter, which keeps the interior clean and is usually worth a small airflow penalty.
Formula
Case Fan Airflow
Temperature rise = heat ÷ (mass flow × specific heat of air)
- static pressure loss
- Filters and mesh reduce intake airflow substantially
- positive pressure
- More intake than exhaust, which keeps dust out
Worked example
With the default values below, Case Fan Airflow Calculator returns Air Temperature Rise of 8.71. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Intake fansminimum 0
- 3
- Exhaust fansminimum 0
- 2
- Airflow per fanminimum 0 cfm
- 55 cfm
- Loss from filters and restrictionaccepts 0–80 %
- 35 %
- System heat outputminimum 0 W
- 450 W
Results
- Air Temperature Rise
- 8.71 C
- Effective Intake Airflow
- 107.25 cfm
- Effective Exhaust Airflow
- 90.75 cfm
- Pressure Balance
- Positive pressure — less dust ingress through unfiltered gaps
- Effective Airflow
- 154.18 m3/h
Step by step
- 1Values used
- 2Case Fan Airflow
- 3Air Temperature Rise= 8.71 C
- 4Effective Intake Airflow= 107.25 cfm
- 5Effective Exhaust Airflow= 90.75 cfm
- 6Pressure Balance= Positive pressure — less dust ingress through unfiltered gaps
- 7Effective Airflow= 154.18 m3/h
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Case Fan Airflow calculated?
Temperature rise = heat ÷ (mass flow × specific heat of air) Airflow removes heat in proportion to mass flow, so doubling airflow halves the temperature rise. Intake filters cost far more airflow than exhaust paths, which is why intake and exhaust are derated differently.
Why does Case Fan Airflow matter?
Positive pressure means all incoming air passes a filter, which keeps the interior clean and is usually worth a small airflow penalty.
What values do I need to enter?
This calculator takes 5 inputs: Intake fans, Exhaust fans, Airflow per fan, Loss from filters and restriction, System heat output. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.