{"uid":"cap_Z5zBsDfpyGHCJXy4tLyFe","slug":"electrical-calculators-transformer-sizing-e1ae9efe","name":"Electrical Calculators – Transformer Sizing","description":"Transformer kVA for a load with a stated margin, next common standard size, and primary and secondary full-load current.","url":"https://electrical-calc.x402tookit.com/transformer-sizing?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":["loadKw","secondaryVoltageV"],"properties":{"phase":{"type":"string","description":"single or three (default three)"},"loadKw":{"type":"number","description":"Connected load in kilowatts"},"marginPct":{"type":"number","description":"Spare capacity margin in percent (default 25, 0 to 200)"},"powerFactor":{"type":"number","description":"Load power factor above 0 to 1 (default 0.9)"},"primaryVoltageV":{"type":"number","description":"Primary (line-to-line if three phase) voltage in volts, for primary current"},"secondaryVoltageV":{"type":"number","description":"Secondary (line-to-line if three phase) voltage in volts"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"asOf":{"type":["null","string"]},"phase":{"type":["null","string"]},"source":{"type":["null","string"]},"loadKva":{"type":["null","number"]},"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"}},"turnsRatio":{"type":["null","number"]},"requiredKva":{"type":["null","number"]},"commonSizesKva":{"type":["array","null"],"items":{"type":"number"}},"spareAtSelectedPct":{"type":["null","number"]},"selectedStandardKva":{"type":["null","number"]},"primaryFullLoadCurrentA":{"type":["null","number"]},"secondaryCurrentAtLoadA":{"type":["null","number"]},"secondaryFullLoadCurrentA":{"type":["null","number"]},"secondaryCurrentAtRequiredKvaA":{"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_DI-Iz-3DuSbpWYlH55Hh-","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 transformer kVA requirement with margin, selects the next standard size, and computes primary and secondary full-load currents.","exampleAgentPrompt":"Size a three-phase transformer for a 75 kW load at 0.85 power factor, 480 V secondary and 11000 V primary, with a 25% spare capacity margin — give me the required kVA, the next standard size, and both primary and secondary full-load currents.","exampleUseCases":[{"title":"New industrial facility transformer selection","prompt":"I'm installing a 120 kW three-phase load at 0.9 power factor on a 415 V secondary fed from a 11000 V primary. Size the transformer with a 20% margin and tell me the standard kVA to order plus primary and secondary full-load currents."},{"title":"Single-phase residential service sizing","prompt":"I need to size a single-phase transformer for a 15 kW residential load at unity power factor, 240 V secondary, with a 30% spare margin. What standard kVA transformer should I buy?"},{"title":"Generator step-up transformer check","prompt":"We have a 200 kW three-phase generator at 0.8 power factor stepping up from 400 V to 33000 V. With a 25% safety margin, what kVA transformer do we need and what are the full-load currents on each side?"}],"resultDescription":"Returns the load kVA, required kVA after applying the margin, the selected next standard transformer kVA size, a list of common standard sizes, primary and secondary full-load currents in amps, secondary current at actual load, turns ratio, spare capacity percentage at the selected size, phase, and a plain-language summary.","failureModes":["Missing required parameters (loadKw or secondaryVoltageV) returns a validation error","Power factor of 0 or outside 0–1 range causes rejection","Negative or zero voltage values are invalid","marginPct outside 0–200 range is rejected","Endpoint returns degraded flag if results are partial or uncertain"],"whenToPreferThis":"Choose this endpoint when you need a complete transformer sizing calculation in one call — covering required kVA with margin, standard size selection, and full-load current calculations for both windings. It is more complete than a standalone kVA calculator because it also returns standard size recommendations and winding currents. Use it when planning transformer procurement for new installations, load upgrades, or verifying existing transformer adequacy.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-11-02T18:32:59.957Z","isFirstParty":false,"canonicalSlug":"electrical-calculators-transformer-sizing-e1ae9efe"}