HVAC Airflow & BTU Load Calculator

Inputs

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Supply, return or ventilation airflow through the coil or heat exchanger.
cfm
Air temperature rise for heating or drop across a cooling coil. Use the absolute difference.
°F
Target sensible capacity used to back-calculate required airflow and ΔT.
Btu/h
Air density at the coil or duct condition. Room-temperature sea-level air is about 1.2 kg/m³.
lb/ft³
Specific heat of air. Dry air near room temperature is about 1.006 kJ/(kg·K).
kJ/kg·K

Results

Default result
Edit inputs
Sensible load(q)
11,440Btu/h
Pass

sensible-only capacity from airflow and temperature difference

Also computed

Airflow for target load(Q_req)789.8cfm

ΔT for target load(ΔT_req)29.82°F

Cooling tons equivalent(tons)0.9535tons

Airflow per ton(CFM/ton)Caution555.6cfm/ton

high airflow per ton; check coil leaving-air temperature and noise

Air mass flow(ṁ)39.68lb/min

Method notes 3 notes
  • Sensible heat only: q = ρ · cₚ · Q · ΔT. It does not include latent/moisture load.
  • With standard air, the same relation is the common imperial shortcut q ≈ 1.08 × CFM × Δ°F.
  • Use Manual J/ASHRAE load methods, equipment data and psychrometrics for final HVAC equipment sizing.

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