Latent Heat Calculator (0.68 × CFM × Δgr)
Latent heat is the energy removed when moisture condenses out of air. It is calculated from the change in humidity ratio across the coil.
HVAC Pro calculator — inputs, formula and example are open to everyone.
Result
Results for this calculator are part of HVAC Pro
You can see the inputs, formula and worked example. Unlock results for every Pro calculator.
Unlock with HVAC ProAlready a member? Sign in
Formula
- Q (BTU/h) = 0.68 × CFM × Δgr
Variables
- Δgr
- — Humidity ratio difference, grains of moisture per lb of dry air
Example calculation
1,200 CFM × 25 gr/lb × 0.68 = 20,400 BTU/h.
Practical HVAC use
Split total cooling load into sensible and latent parts and evaluate dehumidification.
Common mistakes
- Using relative humidity instead of humidity ratio (grains).
Related calculators
Sensible Heat
ProCalculate sensible heat in BTU/h and kW from airflow and temperature difference using Q = 1.08 × CFM × ΔT, with metric inputs.
Total Heat
ProCalculate total (sensible + latent) heat from airflow and enthalpy difference: Q = 4.5 × CFM × Δh. Includes tons and kW.
Dew Point
ProCalculate dew point temperature from air temperature and relative humidity, in °F and °C.
Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators