Smoker Airflow Calculator

Dial in clean smoke with accurate airflow targets. Compare intake, exhaust, and fan assist needs. Better draft means steadier heat and tastier barbecue daily.

Estimate smoker airflow to maintain stable cooking temperatures. Get intake area, exhaust size, and draft guidance. Export results to share settings for repeatable burns nightly.

Inputs

Example: 6–12 cu ft for many backyard cookers.
Typical low-and-slow: 225–275°F.
Used to adjust volumetric flow and draft.
Higher elevation reduces oxygen per cubic foot.
Affects air required for clean combustion.
Estimate from past cooks or a scale test.
Higher values reduce dirty smoke, increase airflow.
Sets chamber air-change target.
Adds cushion for door gaps and seams.
Used to compare exhaust area vs. requirement.
More height generally increases draft.
Effective area = chimney area × opening.
Lower velocity needs more vent area.
Higher velocity reduces required exhaust area.
Reset
Tip: If your cooker runs dirty, increase excess air or open intake.

Example data table

Volume (cu ft) Target (°F) Ambient (°F) Fuel Burn (lb/hr) Excess air (%) Stack (in × ft) Damper (%) Required airflow (CFM) Intake area (in²) Exhaust area (in²)
8.0 250 70 Charcoal 1.50 50 3.0 × 3.0 70 7.5 1.5 1.2
10.0 275 55 Wood 2.20 75 4.0 × 4.0 80 15.0 3.1 2.4
6.5 225 85 Pellets 1.10 40 3.0 × 2.5 60 5.7 1.2 0.9
Examples are illustrative. Your cooker’s leaks and wind can shift results.

Formula used

1) Combustion airflow
Air_scfh = BurnRate(lb/hr) × AirReq(scf/lb) × (1 + ExcessAir%)
CFM_std = Air_scfh ÷ 60
This estimates oxygen demand plus extra air for cleaner smoke.
2) Temperature and elevation adjustment
CFM_actual = CFM_std × (T_avg / T_std) × (P_std / P_local)
Warmer air and higher elevation require more volumetric flow.
3) Chamber exchange airflow
CFM_exchange = Volume(cu ft) × ACH ÷ 60
ACH rises with heavier smoke preferences.
4) Vent free area targets
Area(ft²) = CFM ÷ Velocity(fpm)
Area(in²) = Area(ft²) × 144
“Free area” means after grates, screens, and sliders.

How to use this calculator

  1. Measure your chamber volume in cubic feet.
  2. Enter target and ambient temperatures for your cook.
  3. Choose your fuel, then estimate burn rate.
  4. Set excess air higher for cleaner, lighter smoke.
  5. Enter chimney size and damper opening percentage.
  6. Press Calculate and compare areas to your vents.
  7. If exhaust is smaller, open it or increase stack size.

Safety note

Always confirm good airflow outdoors. Avoid enclosed spaces and carbon monoxide buildup.

{"inputs":{"smoker_volume_cuft":8,"target_temp_f":250,"ambient_temp_f":70,"elevation_ft":0,"fuel_type":"charcoal","fuel_burn_rate_lbh":1.5,"excess_air_percent":50,"smoke_level":"medium","chimney_diameter_in":3,"chimney_height_ft":3,"damper_open_percent":70,"intake_velocity_fpm":700,"exhaust_velocity_fpm":900,"leak_factor_percent":10},"results":[],"generated_at":"2026-02-25 10:43:48"}

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.