Server Room Exhaust Calculator
Exhaust/supply airflow for a small server or IT closet.
Enter your values
Enter the it equipment load in W.
Enter the allowable temperature rise in °F.
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.
- Required airflow
- 948 CFM
- Heat load
- 10,236 BTU/hr
- Recommendation
- Consider dedicated cooling (CRAC/mini-split) instead of ventilation alone
- Redundancy
- Critical rooms should have N+1 cooling, not ventilation alone
Quick answer
Small server rooms without dedicated CRAC units can sometimes be cooled by ventilation alone if the heat load is modest, using CFM = watts x 3.41 / (1.08 x allowable rise).
CFM = (watts x 3.412) / (1.08 x allowable temp rise)
At a glance
| What it does | Exhaust/supply airflow for a small server or IT closet. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | IT equipment load, Allowable temperature rise |
| Main output | Required airflow |
| Formula | CFM = (watts x 3.412) / (1.08 x allowable temp rise) |
| Cost | Free — no sign-up, no download |
How to use the Server Room Exhaust Calculator
- 1Total the IT equipment's electrical load in watts (essentially all becomes heat).
- 2Choose an allowable temperature rise, typically 8-10°F.
- 3For loads above roughly 500-1000 CFM equivalent, dedicated mechanical cooling is safer than ventilation alone.
Inputs explained
- IT equipment load(W)
- Enter the it equipment load in W.
- Allowable temperature rise(°F)
- Enter the allowable temperature rise in °F.
Worked example
Using the values the calculator loads with:
Inputs
- IT equipment load3000 W
- Allowable temperature rise10 °F
Results
- Required airflow948 CFM
- Heat load10,236 BTU/hr
- RecommendationConsider dedicated cooling (CRAC/mini-split) instead of ventilation alone
- RedundancyCritical rooms should have N+1 cooling, not ventilation alone
Frequently asked questions
Can ventilation alone cool a server room?
Only for small loads with a reliable, cool air source — most server rooms need dedicated, redundant cooling to protect uptime.
What temperature should the room be?
ASHRAE recommends 64-80°F (18-27°C) at equipment intake for most IT gear.
What do I need to enter into the Server Room Exhaust Calculator?
Just 2 values: it equipment load, allowable temperature rise. 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 Server Room Exhaust Calculator work out the answer?
Small server rooms without dedicated CRAC units can sometimes be cooled by ventilation alone if the heat load is modest, using CFM = watts x 3.41 / (1.08 x allowable rise). It applies the formula CFM = (watts x 3.412) / (1.08 x allowable temp rise) and shows the working so you can check each step by hand.
Is the Server Room Exhaust 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.