Physics

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Mixed-Air Temperature Calculator.

Calculate the adiabatic sensible mixed temperature of two streams from mass flow, heat capacity, and temperature.

On-device calculationNo signup
01

Set your values

Results update as you type.

Stream 1 heat-capacity rate: 1,005 W/K

Stream 1 heat-capacity rate

0.00000000W/K
Stream 2 heat-capacity rate: 1,005 W/K

Stream 2 heat-capacity rate

0.00000000W/K
Mixed temperature: 303.15 K

Mixed temperature

0.00000000K
Mixed temperature: 30 °C

Mixed temperature

0.00000000°C

Results update automatically as you type.

Educational model with every parameter shown. No material, weather, equipment, or safety defaults are inferred.

Use Cases

HVAC system design

Determine the supply air temperature when mixing return air with fresh outdoor air in ventilation systems.

Example: Mixing 2 kg/s of return air at 295 K with 1 kg/s of outdoor air at 305 K.

Industrial process mixing

Estimate the temperature of combined gas streams in ducts or pipes for process control and equipment sizing.

Example: Blending 0.5 kg/s of hot gas at 500 K with 1.5 kg/s of cold gas at 300 K.

Frequently Asked Questions

What is the mixed-air temperature calculator used for?
It computes the resulting temperature when two air streams mix adiabatically, based on their mass flows, specific heats, and initial temperatures. This is common in HVAC system design and ventilation analysis.
What units should I use for the inputs?
Mass flow must be in kg/s, specific heat in J/(kg·K), and temperature in Kelvin. Ensure consistent units to get the mixed temperature in Kelvin.
Does this calculator account for humidity or latent heat?
No, it only considers sensible heat. It assumes adiabatic mixing without phase changes or moisture effects. For moist air, use a psychrometric calculator.

Tips & Common Mistakes

Tips

  • Ensure both streams use the same units for mass flow, specific heat, and temperature to avoid calculation errors.
  • If specific heat varies with temperature, use an average value over the expected range for better accuracy.
  • For adiabatic mixing, the result is a weighted average based on heat capacity rates (mass flow × specific heat).
  • Double-check that temperatures are in Kelvin, not Celsius, to prevent negative or incorrect results.

Common Mistakes to Avoid

  • Using Celsius instead of Kelvin for temperature inputs, leading to incorrect mixed temperature.
  • Forgetting to convert mass flow to kg/s if given in other units like g/s or lb/h.
  • Assuming the mixed temperature is simply the arithmetic average of the two temperatures, ignoring mass flow and specific heat differences.

Last updated: August 13, 2026