Negative Pressure Kitchen Calculator
Net pressure differential for a commercial kitchen.
Enter your values
Enter the total kitchen exhaust in CFM.
Enter the total kitchen supply/makeup 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.
- Net airflow deficit
- 400 CFM
- Percent negative
- 10%
- Assessment
- Within recommended range
- Target range
- 5-10% negative
Quick answer
A well-balanced commercial kitchen typically runs 5-10% negative relative to its total exhaust, enough to prevent odour migration without making doors hard to operate.
Percent negative = (exhaust - supply) / exhaust x 100
At a glance
| What it does | Net pressure differential for a commercial kitchen. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Total kitchen exhaust, Total kitchen supply/makeup |
| Main output | Net airflow deficit |
| Formula | Percent negative = (exhaust - supply) / exhaust x 100 |
| Cost | Free — no sign-up, no download |
How to use the Negative Pressure Kitchen Calculator
- 1Enter total kitchen exhaust airflow from all hoods.
- 2Enter total supply/makeup air delivered to the kitchen.
- 3Check the resulting percent negative against the 5-10% target range.
Inputs explained
- Total kitchen exhaust(CFM)
- Enter the total kitchen exhaust in CFM.
- Total kitchen supply/makeup(CFM)
- Enter the total kitchen supply/makeup in CFM.
Worked example
Using the values the calculator loads with:
Inputs
- Total kitchen exhaust4000 CFM
- Total kitchen supply/makeup3600 CFM
Results
- Net airflow deficit400 CFM
- Percent negative10%
- AssessmentWithin recommended range
- Target range5-10% negative
Frequently asked questions
What if I can't hit the range exactly?
Adjust the makeup air unit's damper or fan speed, or add transfer air from an adjacent positively-pressured space.
Does outdoor wind affect this?
Yes, wind and stack effect both add variability day to day, so aim for the middle of the target range.
What do I need to enter into the Negative Pressure Kitchen Calculator?
Just 2 values: total kitchen exhaust, total kitchen supply/makeup. 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 Negative Pressure Kitchen Calculator work out the answer?
A well-balanced commercial kitchen typically runs 5-10% negative relative to its total exhaust, enough to prevent odour migration without making doors hard to operate. It applies the formula Percent negative = (exhaust - supply) / exhaust x 100 and shows the working so you can check each step by hand.
Is the Negative Pressure Kitchen 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.