Fidamen

Convert Square Feet to Square Kilometers - Area Converter

Convert area values from square feet (sq ft) to square kilometers (sq km) using SI-consistent definitions. This tool applies the internationally accepted relationships between the foot, metre, and kilometre so results are compatible with scientific and regulatory reporting.

The underlying definition used is that 1 foot = 0.3048 metres exactly (by international agreement). From that exact definition the area relationship follows, enabling repeatable conversions for engineering, land measurement, reporting, and data exchange.

Updated Nov 15, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record eee550ebb8d6 • Reviewed by Fidamen Standards Committee

Interactive Converter

Convert between square foot and square kilometer with precision rounding.

Quick reference table

Square FootSquare Kilometer
1 ft²0 km²
5 ft²0 km²
10 ft²0 km²
25 ft²0 km²
50 ft²0 km²
100 ft²0 km²

Methodology

Start from the exact definition: 1 foot = 0.3048 metres (internationally defined). Square that linear relationship to express one square foot in square metres: 1 sq ft = (0.3048 m)² = 0.09290304 m².

Convert square metres to square kilometres by dividing by 1,000,000 because 1 km = 1,000 m and therefore 1 km² = 1,000,000 m². Combining these steps gives the conversion from square feet to square kilometres.

For high-volume or programmatic uses, use the exact chained definition above rather than a rounded factor to avoid cumulative rounding error. When publishing results, follow the significant-figure or rounding rules required by your regulatory or data consumer context.

Worked examples

Example 1: 1,000 sq ft → 1,000 × 9.290304e-8 = 9.290304e-5 sq km.

Example 2: 435,600 sq ft (one US survey section) → 435600 × 9.290304e-8 = 0.040468564224 sq km (rounded per context).

When converting very large or very small areas, present results with appropriate significant figures or scientific notation to preserve clarity (for instance, 2.5e-4 sq km).

F.A.Q.

Is the conversion factor exact?

Yes. Because 1 foot is defined exactly as 0.3048 metres by international agreement, the derived factor 1 sq ft = 9.290304e-8 sq km is exact to the precision of that definition. Use the exact chained definitions for highest accuracy.

How many significant digits should I display?

Choose significant digits based on the measurement uncertainty of the source value and the reporting requirements of your audience or regulator. For engineering and scientific work, keep at least as many significant digits as present in the original measurement; for public reporting, round to the usual readable precision (for example, 3–6 significant digits).

Does this conversion account for local surveying definitions (US survey feet)?

This converter uses the international foot (1 ft = 0.3048 m exactly). If you require conversions based on the US survey foot or other legacy definitions, convert from that linear definition first and then square it; check relevant land-survey documentation or national mapping agency guidance when exact legacy-unit handling is required.

How should I report converted area in official submissions?

Follow the unit and rounding rules specified by the receiving agency (for example, cadastral authorities, environmental regulators, or statistical offices). Where available, cite the SI definitions (NIST/BIPM) used and include the number of significant digits or rounding method applied.

Can I convert very large datasets without losing precision?

Yes — perform conversions using double-precision arithmetic (or arbitrary-precision libraries when needed) and avoid intermediate rounding. Export results in a format that preserves numeric precision (CSV, JSON with numeric fields) and document the conversion factor used.

Sources & citations

Further resources

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: eee550ebb8d6

What changed (latest)

v1.0.0 • 2025-11-15 • 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 15, 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 • 2025-11-15 • 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: 2fba951d7cb2