{"id":"three-phase-power-calculator","name":"Three-Phase Electrical Power Calculator","shortName":"Three-Phase Power","canonicalUrl":"https://calcurhome.com/calculators/three-phase-power-calculator","catalogUrl":"https://calcurhome.com/api/calculators","category":{"id":"home-energy","name":"Home energy & comfort","url":"https://calcurhome.com/calculators/category/home-energy"},"language":"en-US","audience":"US homeowners, DIYers and home-project planners","primaryKeyword":"three phase electrical power calculation","secondaryKeywords":["3 phase power calculator","three phase kW calculator","three phase kVA calculator","volts amps power factor calculator","three phase horsepower calculator"],"description":"Calculate balanced three-phase kVA, real input kW and estimated output horsepower from line voltage, current, power factor and efficiency.","directAnswer":"Enter average line-to-line voltage, average line current, measured power factor, and equipment efficiency. The calculator estimates balanced three-phase apparent power in kVA, real electrical input in kW, efficiency-adjusted output kW, and horsepower. It does not evaluate phase unbalance, harmonics, motor starting, conductor size, protection, or equipment suitability.","inputs":[{"key":"lineVoltage","label":"Average line-to-line voltage","unit":"V","defaultValue":480,"min":1,"max":50000,"step":1,"help":"Use the average of safely measured phase-to-phase voltages for a balanced planning estimate."},{"key":"lineCurrent","label":"Average line current","unit":"A","defaultValue":20,"min":0.1,"max":50000,"step":0.1,"help":"Use average operating line current; starting and transient current require separate evaluation."},{"key":"powerFactor","label":"Measured power factor","unit":"%","defaultValue":85,"min":1,"max":100,"step":1},{"key":"efficiency","label":"Equipment efficiency","unit":"%","defaultValue":90,"min":1,"max":100,"step":1,"help":"Use current nameplate or test data when estimating mechanical output; use 100% when only electrical input is needed."}],"formula":{"title":"Balanced three-phase apparent and real power","expression":"kVA = √3 × line-to-line volts × line amps ÷ 1,000; input kW = kVA × power factor; output kW = input kW × efficiency; hp = output kW × 1,000 ÷ 746.","explanation":"The square-root-of-three factor relates line quantities in a balanced three-phase system. Power factor converts apparent power to real electrical input, while efficiency estimates useful output. The formula is a steady-state balanced model and cannot diagnose unbalance, harmonics, transients, wiring, protection, or motor performance."},"measurementGuide":["Use a qualified person and appropriately rated instruments to obtain line-to-line voltage, current, power factor, and operating condition data safely.","Average all three phase-to-phase voltages and all three line currents only after recording the individual values and checking whether unbalance is acceptable.","Use measured power factor and efficiency when possible; nameplate or generic assumptions can materially change output estimates.","Record whether measurements represent steady load, startup, unloaded operation, full load, or a changing process before interpreting the result."],"buyingTips":["Do not select motors, conductors, breakers, starters, drives, transformers, capacitors, or generators from this power conversion alone.","Check equipment nameplates, manufacturer curves, duty, service factor, temperature, altitude, enclosure, starting method, harmonics, and load profile.","Have a qualified professional evaluate phase unbalance, protection, available fault current, coordination, grounding, and the adopted electrical requirements.","Measure and trend real equipment under representative conditions before relying on an efficiency or power-factor improvement estimate."],"workedExample":{"title":"Balanced 480-volt motor input estimate","scenario":"A balanced planning measurement averages 480 volts line to line and 20 amperes. Measured power factor is 85%, and the motor's operating efficiency is estimated at 90% for the observed condition.","result":"The model gives about 16.63 kVA and 14.13 kW real electrical input. After the efficiency assumption, estimated output is about 12.72 kW or 17.1 horsepower."},"commonQuestions":[{"question":"Why does three-phase power use the square root of three?","answer":"In a balanced three-phase system, the relationship between line and phase quantities introduces a square-root-of-three multiplier when power is expressed using line-to-line voltage and line current. Different voltage/current definitions or unbalanced systems require the appropriate phase-by-phase method."},{"question":"What is the difference between kVA and kW?","answer":"kVA is apparent power based on voltage and current, while kW is real power doing useful electrical work. Multiplying balanced three-phase kVA by power factor estimates real input kW. Reactive power and distortion can make apparent power larger than real power."},{"question":"Can the calculator determine motor horsepower from the nameplate?","answer":"It estimates output horsepower only when the entered voltage, current, power factor, and efficiency represent the operating condition. Nameplate values describe ratings, not necessarily current shaft output. Direct testing and manufacturer performance information provide better evidence for changing loads."},{"question":"Does averaging the three phases hide electrical problems?","answer":"It can. The balanced formula is useful only after individual phase voltages and currents have been recorded and unbalance, harmonics, and waveform quality have been evaluated. Large differences should be investigated with qualified personnel and appropriate power-quality instruments."}],"sources":[{"name":"Eaton — Power factor correction guide","url":"https://www.eaton.com/content/dam/eaton/products/low-voltage-power-distribution-controls-systems/power-factor-corrections/portfolio/eaton-pfc-guide-plant-engineer-SA02607001E.pdf","note":"Manufacturer engineering guide documenting real power, apparent power, power factor, and balanced three-phase kW and kVA equations."},{"name":"Fluke — Determining three-phase load horsepower","url":"https://www.fluke.com/en-in/learn/blog/power-quality/determining-load-horsepower-wiring-and-breaker-size-for-safe-and-efficient-installations","note":"Test-equipment manufacturer guidance relating measured line voltage, current, efficiency, power factor, three-phase power, and horsepower."},{"name":"NFPA 70 — National Electrical Code development","url":"https://www.nfpa.org/codes-and-standards/nfpa-70-standard-development/70","note":"Official NFPA information for the model electrical code used by adopting jurisdictions; the locally adopted edition and amendments control an installation."}],"defaultCalculation":{"inputs":{"lineVoltage":480,"lineCurrent":20,"powerFactor":85,"efficiency":90},"result":{"value":"14.13","unit":"kW input","label":"Estimated balanced three-phase real power","lines":[{"label":"Apparent power","value":"16.63 kVA"},{"label":"Reactive power","value":"8.76 kVAR"},{"label":"Efficiency-adjusted output","value":"12.72 kW"},{"label":"Estimated output horsepower","value":"17.1 hp"}],"summary":"480 volts line to line and 20 amperes produce 16.63 kVA in the balanced model. At 85% power factor, real input is 14.13 kW; 90% efficiency gives about 17.1 output horsepower.","note":"Use safely obtained measured averages or trusted nameplate data. Unbalanced phases, waveform distortion, motor slip, starting conditions, service design, protection, conductor sizing, and equipment limits require appropriate instruments and qualified review."}},"reviewedOn":"2026-08-03","disclaimer":"Planning estimate only. Verify product coverage, supplier rounding, local codes and structural requirements before purchase or construction."}