Air Flow Rate Calculator
Calculate CFM, air changes, and velocity for HVAC systems
Input Parameters
Method 1: From BTU Capacity
Method 2: From Room Volume & ACH
Method 3: From Duct & Velocity
Air Flow Results
CFM from BTU Capacity
1667 CFM
Formula: BTU ÷ (1.08 × ΔT)
CFM from Room Volume & ACH
160 CFM
Formula: (Volume × ACH) ÷ 60
CFM from Duct & Velocity
800 CFM
Formula: Area × Velocity
Derived Values
Velocity (from BTU):1667 FPMACH (from BTU):62.5Mass Flow:125.00 lb/minCFM per Ton:556Supply Temp:55°F
Typical ACH Requirements
• Bedroom: 4-6 ACH
• Living Room: 6-8 ACH
• Kitchen: 15-20 ACH
• Bathroom: 8-10 ACH
• Commercial: 8-12 ACH
Key Formula:
CFM = Sensible BTU ÷ (1.08 × ΔT)
Where 1.08 = 60 min/hr × 0.075 lb/ft³ × 0.24 BTU/lb·°F