PC Case Pressure Balance Calculator
Intake vs exhaust airflow balance for a PC build.
Enter your values
Enter the total intake fan cfm in CFM.
Enter the total exhaust fan cfm in CFM.
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.
- Pressure balance
- 25%
- Verdict
- Positive pressure (less dust, slightly warmer)
- Net airflow
- 30 CFM
- Recommended target
- +10% to +20% intake for dust control
Quick answer
A PC case with 10-20% more intake than exhaust airflow runs mildly positive, which reduces dust buildup on unfiltered panels.
Balance % = (intake - exhaust) / exhaust x 100
At a glance
| What it does | Intake vs exhaust airflow balance for a PC build. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Total intake fan CFM, Total exhaust fan CFM |
| Main output | Pressure balance |
| Formula | Balance % = (intake - exhaust) / exhaust x 100 |
| Cost | Free — no sign-up, no download |
How to use the PC Case Pressure Balance Calculator
- 1List the rated CFM of every intake fan.
- 2List the rated CFM of every exhaust fan.
- 3Compare the two — slight positive pressure is usually the best trade-off.
Inputs explained
- Total intake fan CFM(CFM)
- Enter the total intake fan cfm in CFM.
- Total exhaust fan CFM(CFM)
- Enter the total exhaust fan cfm in CFM.
Worked example
Using the values the calculator loads with:
Inputs
- Total intake fan CFM150 CFM
- Total exhaust fan CFM120 CFM
Results
- Pressure balance25%
- VerdictPositive pressure (less dust, slightly warmer)
- Net airflow30 CFM
- Recommended target+10% to +20% intake for dust control
Frequently asked questions
Is negative pressure bad?
Not for temperatures, but it pulls dust through every unfiltered gap in the case.
Do fan curves matter?
Yes — rated CFM assumes free air; restriction from filters and radiators lowers real airflow.
What do I need to enter into the PC Case Pressure Balance Calculator?
Just 2 values: total intake fan cfm, total exhaust fan cfm. 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 PC Case Pressure Balance Calculator work out the answer?
A PC case with 10-20% more intake than exhaust airflow runs mildly positive, which reduces dust buildup on unfiltered panels. It applies the formula Balance % = (intake - exhaust) / exhaust x 100 and shows the working so you can check each step by hand.
Is the PC Case Pressure Balance 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.