{"uid":"cap_v3gYsthZzSRZlsiXSVLb4","slug":"hvac-air-changes-per-hour-ach-calculator-244da913","name":"HVAC Air Changes Per Hour (ACH) Calculator","description":"Air changes per hour (ACH) from airflow and room volume, or the CFM needed for a target ACH.","url":"https://hvac-calc.x402tookit.com/air-changes?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":{"ach":{"type":"number","description":"Target air changes per hour to get the CFM needed"},"cfm":{"type":"number","description":"Airflow in CFM to get the ACH; send this or ach"},"widthFt":{"type":"number","description":"Room width in feet"},"heightFt":{"type":"number","description":"Room height in feet"},"lengthFt":{"type":"number","description":"Room length in feet"},"volumeCubicFeet":{"type":"number","description":"Room volume in cubic feet; or send lengthFt, widthFt and heightFt"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"ach":{"type":["null","number"]},"cfm":{"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"}},"volumeCubicFeet":{"type":["null","number"]},"minutesPerChange":{"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_vSF08GKzbjNtqmNk-x8op","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 changes per hour (ACH) from airflow (CFM) and room volume, or computes the CFM needed to achieve a target ACH rate.","exampleAgentPrompt":"What are the air changes per hour for a room that's 20 feet long, 15 feet wide, and 9 feet tall with a fan moving 450 CFM?","exampleUseCases":[{"title":"Verify server room ventilation ACH","prompt":"My server room is 12 feet long, 10 feet wide, and 9 feet tall with a 300 CFM cooling unit — how many air changes per hour is that giving me?"},{"title":"Size fan for target ACH rate","prompt":"I need 8 air changes per hour in a 1,800 cubic foot storage room — what CFM airflow do I need to hit that target?"},{"title":"Check classroom ventilation compliance","prompt":"Our classroom is 30 feet long, 25 feet wide, and 10 feet tall and the HVAC delivers 1,200 CFM. How many air changes per hour are we getting?"}],"resultDescription":"Returns the computed ACH value (if CFM was provided), or the required CFM (if a target ACH was provided), along with the room volume in cubic feet, minutes per air change, a plain-English summary, and an optional disclaimer. Fields may be null if inputs are insufficient.","failureModes":["Missing both CFM and ACH target — endpoint cannot compute without at least one of these","Missing room volume and insufficient room dimensions to derive it — requires volumeCubicFeet or all three of lengthFt/widthFt/heightFt","Non-positive or zero values for dimensions may produce invalid results","HTTP 402 if payment header is not provided or USDC balance is insufficient"],"whenToPreferThis":"Choose this endpoint when you need to quickly compute ACH from known airflow and room dimensions, or size airflow for a ventilation target — it is purpose-built for HVAC ventilation rate math and returns structured results with a human-readable summary, making it ideal for automated HVAC compliance checks, design calculations, or educational tools.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T00:31:12.204Z","isFirstParty":false,"canonicalSlug":"hvac-air-changes-per-hour-ach-calculator-244da913"}