{"uid":"cap_PVROTO9vifuGXfixuBCq0","slug":"plumbing-pipe-flow-calc-drain-slope-calculator-f3f15f8c","name":"Plumbing & Pipe Flow Calc – Drain Slope Calculator","description":"Fall needed for a drain run at a given slope in inches per foot, or the slope of a measured fall, with typical code minimums.","url":"https://plumbing-calc.x402tookit.com/drain-slope?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":["runFeet"],"properties":{"runFeet":{"type":"number","description":"Horizontal run in feet"},"fallInches":{"type":"number","description":"A measured fall in inches, to get the slope instead"},"inchesPerFoot":{"type":"number","description":"Slope in inches of fall per foot (for example 0.25); default 0.25"},"pipeDiameterInches":{"type":"number","description":"Drain diameter in inches, to compare with the usual minimum slope"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"asOf":{"type":["null","string"]},"fallCm":{"type":["null","number"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"runFeet":{"type":["null","number"]},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"disclaimer":{"type":["null","string"]},"fallInches":{"type":["null","number"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"slopeDegrees":{"type":["null","number"]},"slopePercent":{"type":["null","number"]},"slopeRatioOneIn":{"type":["null","number"]},"slopeInchesPerFoot":{"type":["null","number"]},"meetsTypicalMinimum":{"type":["boolean","null"]},"typicalMinimumInchesPerFoot":{"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_I5HDXXkiftR7zLm6P1GDf","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 the fall needed for a drain run at a given slope in inches per foot, or derives the slope from a measured fall, and compares against typical plumbing code minimums.","exampleAgentPrompt":"I have a 20-foot horizontal drain run for a 4-inch pipe — can you calculate how many inches of fall I need at the standard 1/4-inch-per-foot slope and tell me if it meets code minimums?","exampleUseCases":[{"title":"Rough-in drain slope verification","prompt":"I'm roughing in a bathroom drain that runs 18 feet to the stack. The pipe is 3 inches in diameter and I want to use a 1/4-inch-per-foot slope — can you tell me the total fall I need and confirm it meets typical code?"},{"title":"Reverse-engineering slope from a measured fall","prompt":"I already installed a drain and measured a 2.5-inch drop over a 12-foot run on a 2-inch pipe. What slope does that work out to in inches per foot and percent grade, and does it meet the minimum?"},{"title":"Sewer lateral grading check","prompt":"I'm laying a 4-inch sewer lateral that runs 40 feet from the house to the street. What's the total fall in inches at the standard slope, and will it pass a typical inspection?"}],"resultDescription":"Returns the computed fall in inches and centimeters, the slope expressed in inches per foot, percent, degrees, and ratio form, a boolean indicating whether the slope meets typical code minimums, the typical minimum slope for reference, a human-readable summary and verdict, plus any disclaimers or notes about what was not checked.","failureModes":["Missing required runFeet parameter returns an error","Non-numeric or negative runFeet value causes a validation error","Providing neither fallInches nor inchesPerFoot results in default slope (0.25 in/ft) being used","Unknown or unsupported pipe diameter may result in notChecked fields being populated","Service may return degraded:true if reference data is partially unavailable"],"whenToPreferThis":"Choose this endpoint when you need to quickly calculate or verify drain pipe slope and fall for plumbing rough-in or inspection purposes, especially when you want a comparison against typical code minimums. It is ideal for contractors, homeowners, and building inspectors working with horizontal drain runs. Prefer this over a general-purpose calculator when you need plumbing-specific outputs like inches-per-foot slope, code compliance flags, and multi-unit slope representations in a single call.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:11:17.500Z","isFirstParty":false,"canonicalSlug":"plumbing-pipe-flow-calc-drain-slope-calculator-f3f15f8c"}