Convert Kilometers per Hour to Feet per Second - Speed Converter
This converter transforms a single speed value in kilometers per hour (km/h) to feet per second (ft/s) using the internationally defined relationships between metres and feet. It is intended for quick, repeatable conversions for engineering, reporting, and everyday use.
Results are computed from exact unit definitions (1 km = 1000 m; 1 hour = 3600 s; 1 international foot = 0.3048 m). For high-stakes or regulatory measurements, follow the referenced standards and maintain traceable calibration of measurement instruments.
Governance
Record 7e04c35e907f • Reviewed by Fidamen Standards Committee
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Methodology
Conversion applies exact, standard unit definitions. Kilometres are first converted to metres and hours to seconds to obtain metres per second, then metres are converted to feet using the internationally agreed value of 1 foot = 0.3048 metres.
The tool derives a single multiplicative conversion factor from these exact definitions and applies numeric rounding only at the display stage. For precision-critical work, preserve extra significant digits and document uncertainty per the cited standards.
Worked examples
Example 1: 50 km/h → 50 × 0.911344415 = 45.56722075 ft/s ≈ 45.57 ft/s (rounded to 2 decimals).
Example 2: 0 km/h → 0 ft/s (stationary).
F.A.Q.
What is the exact conversion factor from km/h to ft/s?
Using exact definitions (1 km = 1000 m; 1 h = 3600 s; 1 ft = 0.3048 m) the factor is (1000 ÷ 3600) ÷ 0.3048 ≈ 0.911344415. Multiply km/h by this factor to get ft/s.
How accurate are the results from this converter?
The converter uses exact international unit definitions. Numerical results are exact up to floating point limits; displayed values may be rounded. For traceable measurement and reporting follow NIST and ISO guidance and account for instrument uncertainty.
Can I convert from feet per second back to kilometers per hour?
Yes. Use the inverse factor: km/h = ft/s ÷ 0.911344415 (approximately km/h = ft/s × 1.097280254).
When should I worry about calibration or regulatory compliance?
When results are used for safety, legal enforcement, or precise engineering calculations, ensure instruments are calibrated to traceable standards and that you comply with applicable regulations (for example workplace safety rules). Refer to the cited standards for calibration and documentation practices.
What display precision should I use?
Choose precision based on use case: two decimal places are common for display, while engineering analyses may require 4–6 significant digits and documentation of measurement uncertainty.
Are km/h and ft/s SI units?
Kilometres per hour is a commonly used derived unit but the SI base unit for speed is metres per second (m/s). Feet per second is not an SI unit; it is based on the international foot defined in metric terms.
Sources & citations
- NIST Special Publication 811 - Guide for the Use of the International System of Units (SI) — https://www.nist.gov/pml/special-publication-811
- NIST: Reference on the International Foot and Unit Definitions — https://www.nist.gov/pml/weights-and-measures
- ISO 80000-1 Quantities and units (overview and definitions) — https://www.iso.org/standard/30669.html
- IEEE Standards and measurement best practices — https://standards.ieee.org
- OSHA - Occupational safety and health guidance — https://www.osha.gov
Further resources
Related tools
External guidance
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 7e04c35e907fWhat changed (latest)
v1.0.0 • 2025-11-02 • 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 • 2025-11-02 • 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 2, 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 • 2025-11-02 • 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: 1481bbec160b