Convert Horsepower to Kilowatts – Power Converter
This converter translates a single value in horsepower (hp) to the corresponding value in kilowatts (kW). It uses standard SI relationships and calls out the common horsepower variants so you can choose the correct factor for your context.
Use the mechanical horsepower to kilowatt factor for most engineering and automotive conversions. For tasks requiring regulatory compliance, specification matching, or precise loss accounting, check the nameplate definitions and local standards before applying rounded values.
Governance
Record 392267812166 • Reviewed by Fidamen Standards Committee
Interactive Converter
Convert between horsepower and kilowatt with precision rounding.
Quick reference table
| Horsepower | Kilowatt |
|---|---|
| 1 hp | 0.746 kW |
| 5 hp | 3.729 kW |
| 10 hp | 7.457 kW |
| 25 hp | 18.643 kW |
| 50 hp | 37.285 kW |
| 100 hp | 74.57 kW |
Methodology
Power is a physical quantity measured in watts (W) in the International System of Units (SI). Kilowatt is a multiple of watt (1 kW = 1000 W). Horsepower is a non-SI unit historically defined in several ways; the converter maps horsepower to watts and then to kilowatts using established factors.
Primary conversion uses the mechanical (imperial) horsepower definition: 1 mechanical horsepower = 745.699872 watts. Where applicable, a metric or 'PS' definition is provided: 1 metric horsepower (often written as PS or hp (metric)) = 735.49875 watts. Always confirm which hp variant your source uses.
Worked examples
150 hp (mechanical) → 150 × 0.745699872 = 111.8549808 kW (report as 111.85 kW when rounded to two decimals)
10 hp (metric/PS) → 10 × 0.73549875 = 7.3549875 kW (report as 7.355 kW to three decimals)
1 hp (mechanical) → 0.745699872 kW; 1 kW → 1.34102209 mechanical hp (inverse factor)
F.A.Q.
Which horsepower definition should I use?
Use the horsepower definition that matches your source. For engineering and many automotive contexts use mechanical (imperial) horsepower (1 hp = 745.699872 W). If a manufacturer lists 'PS' or 'metric hp', use the metric factor (1 PS = 735.49875 W). If the source is unclear, consult the equipment nameplate or specification sheet.
How many decimal places should I report?
Choose precision according to purpose. For specification sheets and procurement, two to three significant digits after the decimal are common (for example, 111.85 kW). For instrumentation or calculations feeding other models, preserve full precision internally and round only for presentation.
Does this conversion account for mechanical or electrical losses?
No. This converter performs a purely mathematical unit conversion between hp and kW. It does not include losses or efficiency factors. When comparing engine hp to motor kW, include appropriate efficiency or transmission losses separately.
Are there regulatory or standards considerations?
Yes. Use the SI-backed kilowatt values for regulatory reporting where required. For traceable measurements and documentation, follow guidance from recognized standards bodies and maintain measurement uncertainty records if results are used for compliance or safety.
Can I convert back from kW to hp?
Yes. Use the inverse factor: mechanical hp = kW ÷ 0.745699872 (approximately kW × 1.34102209). Be sure to select the correct hp variant when converting back.
Sources & citations
- NIST Guide for the Use of the International System of Units (SI) — https://www.nist.gov/pml/special-publication-811
- ISO 80000-1 Quantities and units — https://www.iso.org/standard/30669.html
- IEEE Standards and Unit Practices — https://standards.ieee.org
- Occupational Safety and Health Administration (OSHA) — https://www.osha.gov
Further resources
Related tools
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 392267812166What changed (latest)
v1.0.0 • 2025-11-25 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-25 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Engine
v1.0.0
Data
Baseline (no external datasets)
Content
v1.0.0
UI
v1.0.0
Governance
Last updated: Nov 25, 2025
Reviewed by: Fidamen Standards Committee (Review board)
Credentials: Internal QA
Risk level: low
Reviewer profile (entity)
Fidamen Standards Committee
Review board
Internal QA
Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person
Semantic versioning
- MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
- MINOR: New features or fields that do not change existing outputs for the same inputs.
- PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.
Review protocol
- Verify formulas and unit definitions against primary standards or datasets.
- Run golden-case regression suite and edge-case suite.
- Record reviewer sign-off with credentials and scope.
- Document assumptions, limitations, and jurisdiction applicability.
Assumptions & limitations
- Uses exact unit definitions from the Fidamen conversion library.
- Internal calculations use double precision; display rounding follows the unit's configured decimal places.
- Not a substitute for calibrated instruments in regulated contexts.
- Jurisdiction-specific rules may require official guidance.
Change log
v1.0.0 • 2025-11-25 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 0f76da898a0f