Mix outdoor and return air by airflow
Calculate mixed-air dry-bulb temperature, humidity ratio and outdoor-air percentage from two airstreams.
Project inputs
Mixed Air Calculator results
How this Mixed Air Calculator works
Dry-bulb temperature and humidity ratio are independently airflow-weighted.
What assumptions should I verify?
The Mixed Air Calculator uses U.S.-first defaults where conventions affect Outdoor airflow CFM, Outdoor dry-bulb °F, and Outdoor humidity ratio lb/lb; its visible selectors identify alternate measurements explicitly. The reported Total mixed airflow, Mixed dry-bulb, and Mixed humidity ratio follows the selected units and the same canonical equation W = (oa × Out Humidity+ra × Ret Humidity) ÷ total.
Is information sent anywhere?
The Mixed Air Calculator evaluates W = (oa × Out Humidity+ra × Ret Humidity) ÷ total locally in the browser. Values entered for Outdoor airflow CFM, Outdoor dry-bulb °F, and Outdoor humidity ratio lb/lb are used to produce Total mixed airflow, Mixed dry-bulb, and Mixed humidity ratio inside the `mixed-air` module and are not transmitted to a remote solver or stored by this calculator.
Mixed Air Calculator: formula-based step-by-step solution
This Mixed Air Calculator worked derivation uses the published default state. Its live formula panel replaces these values whenever an input, unit, mode, date, material, or scenario changes.
W = (oa × Out Humidity+ra × Ret Humidity) ÷ totalRa = Ret CfmOa = Out CfmTotal = oa+raTemp = (oa × Out Temp+ra × Ret Temp) ÷ totalHumidity = (oa × Out Humidity+ra × Ret Humidity) ÷ totalOutdoor Pct = oa ÷ total × 100Return Pct = ra ÷ total × 100
1. Governing formulas and numeric substitution
- Formula 1:
W = (oa × Out Humidity+ra × Ret Humidity) ÷ totalDefault-value substitution:W = (oa × (0.014)+ra × (0.009)) ÷ total - Formula 2:
Ra = Ret CfmDefault-value substitution:Ra = (1500)Intermediate evaluation:1500 - Formula 3:
Oa = Out CfmDefault-value substitution:Oa = (500)Intermediate evaluation:500 - Formula 4:
Total = oa+raDefault-value substitution:Total = (500)+(1500)Intermediate evaluation:2000 - Formula 5:
Temp = (oa × Out Temp+ra × Ret Temp) ÷ totalDefault-value substitution:Temp = ((500) × (95)+(1500) × (75)) ÷ (2000)Intermediate evaluation:80 - Formula 6:
Humidity = (oa × Out Humidity+ra × Ret Humidity) ÷ totalDefault-value substitution:Humidity = ((500) × (0.014)+(1500) × (0.009)) ÷ (2000)Intermediate evaluation:0.01025 - Formula 7:
Outdoor Pct = oa ÷ total × 100Default-value substitution:Outdoor Pct = (500) ÷ (2000) × 100Intermediate evaluation:25 - Formula 8:
Return Pct = ra ÷ total × 100Default-value substitution:Return Pct = (1500) ÷ (2000) × 100Intermediate evaluation:75
2. Variables and measurement units used
- Outdoor airflow CFM =
500CFM - Outdoor dry-bulb °F =
95°F - Outdoor humidity ratio lb/lb =
0.014lb/lb - Return airflow CFM =
1500CFM - Return dry-bulb °F =
75°F - Return humidity ratio lb/lb =
0.009lb/lb
3. Mixed Air Calculator final evaluation: this calculator’s production engine evaluates the substituted relationship with unrounded internal precision; its subject-specific result cards, table, and visual report the rounded final answer and verification quantities.
Formula-based calculator guide
Mixed Air Calculator: formula, steps, units and verification
mixed air calculator is designed for a transparent calculation rather than a black-box answer. Mixed Air Calculator: calculate mixed-air dry-bulb temperature, humidity ratio and outdoor-air percentage from two airstreams. U.S.-first inputs.
How to use the mixed air calculator in 5 steps
- Choose the required mode. Select the calculation path that matches the quantity you know and the result you need.
- Enter source values. Use measured, documented or assignment values rather than rounded estimates whenever possible.
- Confirm every unit. The mixed air calculator converts supported units before formula substitution, so each selector must describe the entered number.
- Run the calculation. Review the displayed formula, normalized values and numeric substitution before accepting the final result.
- Verify the answer. Reproduce the substitution manually and check whether the output is reasonable for the stated assumptions.
Mixed Air Calculator formula and unit checks
The mixed air calculator keeps source inputs, canonical calculation units and displayed output units separate. This prevents a correct formula from producing a wrong answer because feet were treated as meters, percentages as decimals, or time values as the wrong interval.
For an independent check, copy the formula shown by the calculator, substitute the unrounded canonical values, preserve full precision through intermediate operations and round only the final result. The verified answer should match both the displayed number and its measurement unit.
How to interpret the mixed air calculator result
A result is useful only when its assumptions match the real problem. Compare the answer with expected ranges, inspect any warning or boundary message, and test a nearby input to confirm that the output changes in the direction predicted by the governing relationship.
The mixed air calculator provides an educational and planning result. For regulated, medical, structural, financial, laboratory or safety-critical decisions, verify the inputs and method against the applicable professional requirements before acting.
Related calculators
Mixed Air Calculator quick verification checklist
Before saving or reporting a result from the mixed air calculator, confirm the input source, unit selections, formula mode, intermediate substitution, final unit and rounding rule. These checks make the calculation reproducible and easier to audit.
Browse the complete published calculator sitemap or return to the Salar Cafe home page.