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Three-Phase Power Calculator

Calculate real power (kW) for a three-phase electrical load from voltage, current, and power factor.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Real power

35.33 kW

High confidence
Apparent power
41.57 kVA

For the dimensions entered, expect a real power of 35.3 kW. Note that current sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Add the equipment this sizes

This result is a specification — 35.334 kW — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Standard three-phase power formula: P = sqrt(3) x V x I x power factor

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why does three-phase power use sqrt(3) instead of just multiplying voltage by current?
In a three-phase system, the three phases are offset by 120°, so their combined power isn't a simple sum — the sqrt(3) factor (approximately 1.732) accounts for this phase relationship in the standard line-to-line voltage power formula.
What's the difference between kW and kVA?
kVA is apparent power (voltage x current, ignoring phase angle); kW is real power, the actual usable power after accounting for power factor — kW is always less than or equal to kVA, and equipment ratings sometimes use one or the other depending on the context.
Where would I use this calculation?
Common uses include sizing generators, transformers, or panels for three-phase equipment like large HVAC units, industrial motors, or commercial pump systems.