Mixed Air Temperature Calculator
Find the resulting temperature when two air streams are blended. Enter the flow rate and temperature of each stream — the calculator computes the flow-weighted average mixed temperature and shows the fraction each stream contributes.
CFM / m³h
°C / °F
CFM / m³h
°C / °F
Flow-weighted average of both streams (same temperature unit as inputs)
- 1
Total flow
1,000 + 3,000 = 4,000 - 2
Weighted heat — stream 1
1,000 × 35 = 35,000 - 3
Weighted heat — stream 2
3,000 × 24 = 72,000 - 4
Mixed temperature
(35,000 + 72,000) ÷ 4,000 = 26.75
How does this calculator work?
Mix temperature = (Q₁ × T₁ + Q₂ × T₂) / (Q₁ + Q₂). Enter flow rate and dry-bulb temperature for each stream; the result is the flow-weighted average. For 1000 CFM at 35° and 3000 CFM at 24°: (1000×35 + 3000×24)/4000 = 26.75°. Works in °C or °F with any flow unit.
Formula
How this is calculated
When two air streams are combined in a duct or mixing box, the resulting temperature is a flow-weighted average of the two inlet temperatures. Each stream contributes proportional to its volumetric flow rate: a stream with three times the flow has three times the influence on the mix temperature.
The formula T_mixed = (Q₁T₁ + Q₂T₂) / (Q₁ + Q₂) works with any consistent flow unit (CFM, m³/h, L/s) and any temperature scale (°C or °F) — just make sure both streams use the same units. The result will be in the same temperature unit and will always fall between the two inlet temperatures.
This is the fundamental "sensible heat mixing" calculation and forms the basis of all more complex psychrometric calculations. It assumes the streams mix fully and instantaneously, that no condensation occurs, and that the specific heat of air is the same for both streams — valid assumptions for typical HVAC mixing applications.
Frequently asked questions
T_mix = (Q₁ × T₁ + Q₂ × T₂) / (Q₁ + Q₂), where Q is the flow rate (in any consistent unit) and T is temperature. The result is a flow-weighted average that lies between the two inlet temperatures.
Yes — this is the core HVAC mixed-air point calculation. Set stream 1 to your outdoor air (OA) flow and temperature, and stream 2 to your return air (RA) flow and temperature. The result is the mixed-air (MA) temperature entering the cooling or heating coil.
No — this calculator handles only dry-bulb temperature (sensible heat). For a complete psychrometric calculation that includes humidity ratio, enthalpy, and wet-bulb temperature of the mixed air, use the Mixed Air Calculator.
Also known as
TG we-Calculate Editorial Team. (2026). Mixed Air Temperature Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/mixed-air-temperature-calculator
TG we-Calculate Editorial Team. "Mixed Air Temperature Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/mixed-air-temperature-calculator.
TG we-Calculate Editorial Team, "Mixed Air Temperature Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/mixed-air-temperature-calculator
@misc{wecalculate_mixed_air_temperature_calculator, title = {Mixed Air Temperature Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/mixed-air-temperature-calculator}}, year = {2026}, note = {TG we-Calculate} }
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