Kitchen Ventilation Need Calculator

Calculator Inputs

The calculator uses a single-column page layout, while the input fields shift to 3 columns on large screens, 2 on medium screens, and 1 on mobile.

Kitchen Length (ft)

Kitchen Width (ft)

Kitchen Height (ft)

Hood Length (ft)

Hood Depth (ft)

Hood Style

Appliance Duty Level

Custom Capture Velocity (fpm)

Enter 0 to use the built-in duty and hood style method.

Appliance Sensible Heat Load (BTU/h)

Allowable Temperature Rise (°F)

Target ACH

Diversity Factor

Safety Factor

Makeup Air (% of Exhaust)

Fan Static Pressure (in.w.g.)

Fan Efficiency (%)

Operating Hours per Day

Operating Days per Year

Energy Cost per kWh

Example Data Table

Kitchen Size	Hood Size	Duty	Heat Load	Target ACH	Recommended Exhaust
20 × 14 × 10 ft	10 × 4 ft	Heavy	120,000 BTU/h	35	5,016.00 CFM

This example reflects the default starting values shown in the form and helps users verify the calculator behavior quickly.

Formula Used

1) Room Volume
Room Volume (ft³) = Length × Width × Height

2) Hood Face Area
Hood Area (ft²) = Hood Length × Hood Depth

3) Face Method Exhaust
Face Method CFM = Hood Area × Effective Capture Velocity × Diversity Factor × Safety Factor

4) ACH Method Exhaust
ACH Method CFM = (Room Volume × Target ACH) ÷ 60

5) Heat Method Exhaust
Heat Method CFM = Sensible Heat Load ÷ (1.08 × Allowable Temperature Rise)

6) Final Recommended Exhaust
Recommended Exhaust CFM = Maximum of Face Method, ACH Method, and Heat Method

7) Makeup Air
Makeup Air CFM = Recommended Exhaust × Makeup Air Percentage

8) Fan Brake Horsepower
Fan BHP = (CFM × Static Pressure) ÷ (6356 × Fan Efficiency)

9) Fan Power and Annual Cost
Fan kW = BHP × 0.7457
Annual Energy = kW × Hours/Day × Days/Year
Annual Cost = Annual Energy × Energy Cost per kWh

How to Use This Calculator

Enter the kitchen length, width, and height.
Input hood length and depth for the planned capture area.
Select hood style and appliance duty level.
Add heat load, ACH target, and allowable temperature rise.
Set diversity, safety, makeup air percentage, and fan details.
Enter operating schedule and electricity rate for annual energy cost.
Click Calculate Ventilation Need.
Review the result block above the form, then export CSV or PDF if needed.

Frequently Asked Questions

1. What does this calculator estimate?

It estimates kitchen exhaust airflow, makeup air, air changes, fan power, and annual energy cost. It compares hood capture, room ACH, and heat-removal methods, then selects the controlling airflow requirement.

2. Why does the calculator use three airflow methods?

Commercial kitchen ventilation should not rely on one check only. Hood capture, space air change rate, and appliance heat release can each control the design, depending on the room and equipment layout.

3. What is capture velocity?

Capture velocity is the air speed needed at the hood face to pull heat, grease, smoke, and vapors into the exhaust hood. Higher-duty cooking generally needs a higher value.

4. Why is makeup air important?

Without enough replacement air, the kitchen can become overly negative. That can reduce hood performance, affect comfort, pull in unfiltered air, and cause doors to become harder to open.

5. What does residual negative balance mean?

It is the remaining difference between exhaust and supplied makeup air. A modest negative balance can be intentional, but a large one may create pressure and performance problems.

6. Can I override the built-in capture velocity?

Yes. Enter a custom value in the capture velocity field. If you leave it at zero, the calculator uses the selected duty level and hood style factors automatically.

7. Is this suitable for final code compliance?

It is a practical planning and estimating tool. Final compliance should still be checked against local mechanical codes, hood listing requirements, equipment schedules, and project engineer review.

8. Why does fan power increase so quickly?

Fan power rises with airflow and static pressure. Poor duct routing, dirty filters, or low efficiency can significantly increase motor energy demand over a full operating year.