{"uid":"cap_U8iotP7lWCu8YH1WWIeua","slug":"hvac-duct-velocity-velocity-pressure-calculator-b30fd5d3","name":"HVAC Duct Velocity & Velocity Pressure Calculator","description":"Air velocity (FPM) and velocity pressure (in. wg) in a round or rectangular duct from CFM, or the CFM at a velocity.","url":"https://hvac-calc.x402tookit.com/duct-velocity?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":[],"properties":{"cfm":{"type":"number","description":"Airflow in CFM to get the velocity; send this or fpm"},"fpm":{"type":"number","description":"Velocity in feet per minute to get the CFM"},"widthIn":{"type":"number","description":"Rectangular duct width in inches"},"heightIn":{"type":"number","description":"Rectangular duct height in inches"},"diameterIn":{"type":"number","description":"Round duct diameter in inches; or send widthIn and heightIn"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"cfm":{"type":["null","number"]},"fpm":{"type":["null","number"]},"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"areaSquareFeet":{"type":["null","number"]},"areaSquareInches":{"type":["null","number"]},"velocityPressureInWg":{"type":["null","number"]}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_JYmUj93x24bmgoFXqBXKt","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"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.","exampleAgentPrompt":"What's the air velocity and velocity pressure in a 10-inch round duct carrying 600 CFM?","exampleUseCases":[{"title":"Duct sizing for new HVAC install","prompt":"I'm designing a supply duct system — what velocity and velocity pressure will I get in a 12-inch round duct moving 900 CFM?"},{"title":"Verify velocity in rectangular return air duct","prompt":"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?"},{"title":"Find CFM needed for target duct velocity","prompt":"I need to hit 800 feet per minute in a 14-inch round duct — how many CFM does that require?"}],"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:13:44.356Z","isFirstParty":false,"canonicalSlug":"hvac-duct-velocity-velocity-pressure-calculator-b30fd5d3"}