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HVAC Duct Velocity & Velocity Pressure Calculator
x402
HVAC Duct Velocity & Velocity Pressure Calculator is a paid API for AI agents from hvac-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Calculates air velocity (FPM) and velocity pressure (in. wg) in a round or rectangular duct from CFM, or the CFM required to achieve a given velocity.
Price / call$0.02
Success—
StatusUnknown
How this service works
Air velocity (FPM) and velocity pressure (in. wg) in a round or rectangular duct from CFM, or the CFM at a velocity.
Output
Returns calculated air velocity in FPM, velocity pressure in inches water gauge (in. wg), duct cross-sectional area in both square inches and square feet, and the input CFM or FPM (whichever was derived). Also includes a summary, disclaimer, and data timestamp.
Example use cases
Duct sizing for new HVAC install
“I'm designing a supply duct system — what velocity and velocity pressure will I get in a 12-inch round duct moving 900 CFM?”
Verify velocity in rectangular return air duct
“Can you check the airflow velocity in a 16-inch wide by 10-inch tall rectangular duct carrying 1,200 CFM, and give me the velocity pressure too?”
Find CFM needed for target duct velocity
“I need to hit 800 feet per minute in a 14-inch round duct — how many CFM does that require?”
Technical details
Endpoint
GEThttps://hvac-calc.x402tookit.com/duct-velocity?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to compute duct air velocity (FPM) or velocity pressure (in. wg) from a known airflow rate and duct geometry, or reverse-calculate CFM from a target velocity — specifically for round or rectangular ducts in HVAC design, commissioning, or troubleshooting contexts.
Side effects
- Missing both cfm and fpm — must provide at least one
- Missing both diameterIn and widthIn/heightIn — duct dimensions required
- Non-positive or zero values for dimensions may produce errors
- Rectangular duct requires both widthIn and heightIn together
- Very large or unrealistic values may return warnings or degrade gracefully
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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