Electrical calculator

kVA to kW Calculator

Convert apparent power (kVA) to real power (kW) with power factor. States when PF is required and when loads are assumed balanced. Try it free.

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Trust summary CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance

Input interpretation: Enter values to calculate.
Result: —
Assurance: Engineering
Declared partition coverage: PASS · 3/3 declared partitions (kva-kw, kw-kva, invalid-domain) · Matrix
Known limitations: Sinusoidal PF model; no distortion factor
Core CVP does not include live graph, viewport, or pointer interaction.
Model: Real power in kW from kVA and PF, or apparent power in kVA from kW and PF.
Scope: PF is the displacement/true power factor relating P and S
Verification: Engine tested · Source checked · v1.4.1 · CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Versions: Calculation 1.4.1 · CVP protocol 1.0.0-proposed
CVP identity: 3/3 property · digest e00f9aa8ed23
Legacy regression: 14/14 tests · Production surface contract 2/2
Reference: O1 model · O2 expected_values · O2 numerical_behavior
Interfaces: PASS · UI (SSR) / REST / MCP — ui-ssr is query-result HTML, not a live browser session.
Supplemental domain review: Internal · Pass · electrical-engineer
Named expert review: Not performed
CVP suite: 2/2 golden · 4/4 CVP boundary · 4/4 invalid · 3/3 property · 1/1 cross-interface · 1/1 CVP contract · Manifest
Sources: IEC 60050 — International Electrotechnical Vocabulary — Apparent power (IEV 131-11-41)
IEC 60050 — International Electrotechnical Vocabulary — Power factor (IEV 131-11-46)
IEEE Std 1459-2025 — Relationship P = S × PF for sinusoidal conditions
BIPM SI Brochure (9th edition, version 4.01) — SI units for watt and volt-ampere
NIST Guide to the SI (SP 811) — Kilowatt and related power units
Sources
Evidence: 7 legacy golden · 4 legacy boundary · legacy regression suite · 2/2 oracle-backed golden · 4/4 invalid · Artifact integrity PASS · CalculatorX electrical review
Semantic contract: PASS

Full verification

Manifest identity, reference classes, interfaces, suite, and production records.

Formulas

Core equations used by this calculator.

kVA → kWkW = kVA × PF

kW → kVAkVA = kW ÷ PF

Power factorPF = kW ÷ kVA

iPF is dimensionless, typically 0–1 (lagging for inductive loads). At PF = 1, kW = kVA. Many gensets use PF = 0.8, so kW ≈ 0.8 × kVA and kVA ≈ kW × 1.25. Phase (1φ/3φ) is not required for this conversion.

How to use

Choose kVA → kW or kW → kVA

Forward mode needs apparent power; reverse needs real power.

Enter power and power factor

Use nameplate PF when available. Generators often use 0.8.

Read kW or kVA

Result updates as you type. To get amps, continue with kVA to amps (needs voltage and phase).

Example calculations

Common configurations with formula and result.

100 kVA genset at PF 0.8

Common generator rating

100 × 0.8

80 kW

50 kVA · PF 0.9

Higher efficiency load

50 × 0.9

45 kW

10 kVA · PF 0.85

Motor-style PF

10 × 0.85

8.5 kW

kW → kVA at PF 0.8

80 kW real power

80 ÷ 0.8

100 kVA

Unity power factor

25 kVA · PF 1

25 × 1

25 kW

Generator shortcut — PF 0.8 (kW = 0.8 × kVA)

Common values at a glance.

kVA	kW (PF 0.8)	Note
5	4	Small portable
10	8
50	40
100	80	kVA × 1.25 ↔ kW
150	120
200	160
250	200
500	400
750	600
1,000	800

i Matches common genset tables at PF 0.8. Amps still need voltage and phase — use kVA to amps. Not valid for every site voltage.

kVA to kW calculator specification

Version 1.4.1 · Engine tested · Supplemental domain review · Internal · 2026-08-08

Calculation status

Engine tested 14/14 tests · Production surface contract 2/2
Supplemental domain review Internal · Pass · electrical-engineer · 2026-08-08
Named expert review Not performed
Calculation version 1.4.1

Review policy · Evidence · Reviewed by CalculatorX electrical review (electrical-engineer)

Definition: Kilovolt-amperes (kVA) measure apparent power; kilowatts (kW) measure real power. They are linked by power factor: kW = kVA × PF and kVA = kW ÷ PF. This conversion does not need voltage or phase — only apparent (or real) power and PF. Generators are often rated at PF 0.8.
What it calculates: Real power in kW from kVA and PF, or apparent power in kVA from kW and PF.
Inputs: Apparent power S (kVA) or real power P (kW)
Power factor PF (0–1)
Outputs: Real power in kW
Apparent power in kVA
Formula: P = S × PF; S = P ÷ PF
Assumptions: PF is the displacement/true power factor relating P and S
Voltage and phase are not required when S or P is already known
Units: kVA, PF → kW
Boundary conditions: power_factor must be in (0, 1] — PF≤0 → FRACTION_OUT_OF_RANGE (engine kva-kw)
Missing PF → MISSING_REQUIRED_INPUT
Zero kVA/kW yields 0 — soft boundary
Example: 100 kVA × 0.8 = 80 kW
Validation cases: 13 published on this page · 14/14 tests · Production surface contract 2/2 · View evidence
100 kVA, PF 0.8 → 80 kW
50 kVA, PF 0.9 → 45 kW
10 kVA, PF 0.85 → 8.5 kW
80 kW, PF 0.8 → kVA → 100 kVA
25 kVA, PF 1 → 25 kW
200 kVA, PF 0.8 (2×) → 160 kW (linear in kVA)
100 kVA, PF 0.4 (half PF) → 40 kW (linear in PF)
80 kW, PF 0 → kVA → 0 kVA (soft: PF=0 on quotient → 0)
100 kVA, PF 0 → 0 kW
0 kVA, PF 0.8 → 0 kW
50 kVA, PF 0.5 → 25 kW
0 kW, PF 0.8 → kVA → 0 kVA
100 kVA → kW → kVA round-trip at PF 0.8 → 100 kVA
Sources: IEC 60050 — International Electrotechnical Vocabulary — Apparent power (IEV 131-11-41) · accessed 2026-09-05
Supports: kVA is apparent power S; unit volt-ampere (VA) at 10³ scale
IEC 60050 — International Electrotechnical Vocabulary — Power factor (IEV 131-11-46) · accessed 2026-09-05
Supports: λ = |P| / S; P(kW) = S(kVA) × λ and S = P ÷ λ
IEEE Std 1459-2025 — Relationship P = S × PF for sinusoidal conditions · 2025-05-16 · errata checked · accessed 2026-09-05
Supports: P(kW) = S(kVA) × PF; S = P ÷ PF
BIPM SI Brochure (9th edition, version 4.01) — SI units for watt and volt-ampere · 2026-06 · DOI · accessed 2026-09-05
Supports: kW / kVA unit relationships; kilo (k) = 10³
NIST Guide to the SI (SP 811) — Kilowatt and related power units
Supports: kW / kVA unit relationships
Last reviewed: 2026-08-08
Reviewed by: CalculatorX electrical review (electrical-engineer)
Calculation version: 1.4.1

Background

Interpretation and common distinctions.

Convert kilovolt-amps (kVA) to kilowatts (kW) — or reverse — using power factor:

P((kW)) = S((kVA)) × PF S((kVA)) = (P((kW)))/PF

Default example: 100 kVA × 0.8 = 80 kW (typical genset rating).

kVA vs kW

Quantity	Symbol	Meaning
Apparent power	kVA	Voltage × current capacity of the source / wiring
Real power	kW	Power that does work or becomes heat
Power factor	PF	PF = kW / kVA (usually 0–1)

At PF = 1, kW equals kVA. At lower PF, the same kVA delivers less real power.

Do I need voltage or phase?

Not for this step. Once you have kVA (or kW) and PF, the conversion is complete.

Goal	Inputs	Tool
kVA ↔ kW	Power + PF	This calculator
kVA → amps	kVA + V + phase	kVA to amps
Amps → kW	A + V + PF + phase	Amps to kW

Some sites also offer V/I-based 1φ/3φ calculators; those compute power from current and voltage. Here you already start from kVA or kW.

Typical power factors

Load	Typical PF
Resistive heater / incandescent	≈ 1.00
UPS / IT (varies)	0.9–1.0
Induction motor (full load)	≈ 0.85
Standby generator rating	often 0.8
Induction motor (light load)	can be much lower

Prefer nameplate or measured values when sizing equipment.

Other calculators in this family: Amps to kW Calculator, Amps to VA Calculator, Amps to Volts Calculator, Electric Power Calculator, Energy Consumption Calculator, Energy Cost Calculator, eV to Volts Calculator, kVA to Amps Calculator . Explore all Power & Energy.

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Frequently asked questions

Key distinctions behind the calculation.

How do I convert kVA to kW?

Multiply apparent power by power factor: kW = kVA × PF. Example: 100 kVA × 0.8 = 80 kW.

How do I convert kW to kVA?

Divide real power by power factor: kVA = kW ÷ PF. At PF 0.8, kVA = kW × 1.25.

What is the difference between kVA and kW?

kVA is apparent power (how hard the supply is loaded in volts × amps). kW is real power that does work or becomes heat. kW is always ≤ kVA for PF ≤ 1.

Do I need single-phase or three-phase for this conversion?

No. Once you already have kVA (or kW) and PF, phase is not in the formula. Phase matters when you calculate kVA or kW from volts and amps.

What power factor should I use?

Prefer the equipment nameplate or measured PF. Resistive heaters ≈ 1. Many induction motors ≈ 0.8–0.9 at full load. Standby generators are often rated at PF 0.8.

Why do generators list both kVA and kW?

The kVA rating limits current (thermal / winding capability). The kW rating is the real power available at the stated PF — often 0.8 × kVA.

How do I get amps from kVA or kW?

From kVA: use kVA to amps with voltage and phase (PF not required). From kW: use amps to kW reverse path, which needs voltage, phase, and PF.

Is PF the same as efficiency?

No. Power factor is the ratio of real to apparent power (cosine of phase angle for sinusoidal systems). Efficiency is output power divided by input power and is a separate factor (e.g. in hp formulas).