Square Kilometers to Acres Converter - Convert km² to acres (Exact: 1 km² = 247.105381467165 acres)
Accurate square kilometers (km²) to acres converter using exact metric–US relationships. Ideal for land planning, agriculture, forestry, conservation, and real estate. Includes exact formulas, step-by-step examples, expanded tables, rounding guidance, detailed FAQs, and practical tips.
Exact factor: 1 km² = 247.105381467165 acres ⇒ acres = km² × 247.105381467165. See all agricultural land area converters.
About Square Kilometers to Acres Conversion
The square kilometer (km²) is the standard for large tracts: districts, watersheds, protected areas, and regional planning. The acre (ac) is commonly used in U.S. land markets, ranching, and many ag/forestry datasets. Converting km² to acres helps you present results in a familiar U.S. unit while keeping your analytics clean in SI. Because the underlying constants are exact, you can move confidently between km², hectares, m², and acres without drift.
A practical modeling pattern is: compute geometry in your GIS/engine, output areas in m², and derive km², ha, and acres only for presentation. Rounding once at display time avoids the classic double-rounding mismatch between maps, PDFs, emails, and CSV exports.
Square Kilometers to Acres Formula
Exact relationship
Use either expression:
acres = km² × (1,000,000 ÷ 4,046.8564224)
// simplified
acres = km² × 247.105381467165
// inverse
km² = acres × 4,046.8564224 ÷ 1,000,000Example:
2.75 km² × 247.105381467165 = 680.53980 acresRelated Area Converters
What is a Square Kilometer (km²)?
A square kilometer is the area of a square 1,000 meters on each side. It equals 1,000,000 m² and exactly 100 hectares. It’s ideal for regional summaries-city parks networks, habitat extents, and land-use classes. For national stats, km² gives compact values while remaining tightly aligned with SI.
What is an Acre (ac)?
The international acre is defined as exactly 4,046.8564224 m². It remains common in U.S. property listings, agriculture, and many government datasets. When communicating with U.S. stakeholders, showing acres alongside km² or hectares improves comprehension while your backend stays consistent in SI units.
Step-by-Step: Converting km² to acres
- Compute the area in m² or km² from your geometry or survey.
- Multiply by 247.105381467165 to convert km² → acres.
- Round once at presentation (e.g., 2–3 decimals for dashboards; more for technical annexes if required).
Example walkthrough:
Input: 0.84 km²
Compute: 0.84 × 247.105381467165 = 207.56852 acres
Output: 207.57 acres (UI policy: 2 decimals; store full precision internally)Common Conversions
Everyday quick checks (km² → acres)
| km² | acres | km² | acres |
|---|---|---|---|
| 0.10 | 24.71054 | 1.00 | 247.10538 |
| 0.25 | 61.77635 | 2.50 | 617.76345 |
| 0.50 | 123.55269 | 5.00 | 1,235.52691 |
| 0.75 | 185.32904 | 10.00 | 2,471.05381 |
| 0.84 | 207.56852 | 25.00 | 6,177.63454 |
Quick Reference Table
Acres to square kilometers (ac → km²)
| acres | km² | acres | km² |
|---|---|---|---|
| 25 | 0.10117141 | 250 | 1.01171410 |
| 50 | 0.20234282 | 500 | 2.02342820 |
| 100 | 0.40468564 | 1,000 | 4.04685642 |
| 150 | 0.60702846 | 2,500 | 10.11714106 |
| 500 | 2.02342820 | 10,000 | 40.46856422 |
Precision, Rounding & Significant Figures
Operational rounding
For public dashboards and press releases, 2–3 decimals in acres are typically enough. For compliance filings or survey annexes, align decimals with your measurement method and uncertainty. Compute in full precision and round once at presentation to keep maps, PDFs, and exports synchronized.
Consistent documentation
Standardize field names (e.g., area_m2, area_km2, area_ha, area_ac) and include a short methods note: “Exact constants; 1 ac = 4,046.8564224 m²; 1 km² = 1,000,000 m²; round once at presentation.” Consistency prevents subtle discrepancies during audits and reconciliations.
Where This Converter Is Used
- 🌾 Agriculture: Converting regional field blocks in km² to acres for U.S. stakeholders and budgeting.
- 🌳 Forestry & conservation: Reporting reserve footprints, burn perimeters, and habitat extents in acres.
- 🏞️ Parks & planning: City and county park inventories that need both km² and acre summaries.
- 🏡 Real estate & appraisal: Cross-border land listings and valuations that align with U.S. customary units.
- 🛰️ GIS & remote sensing: Raster and vector area rollups in m²/km² converted to acres for end-user familiarity.
Frequently Asked Questions
What is the exact formula to convert square kilometers to acres?
Start from the international acre: 1 acre = 4,046.8564224 m² (exact). Since 1 km² = 1,000,000 m² (exact), divide by the acre: acres = km² × (1,000,000 ÷ 4,046.8564224) = km² × 247.105381467165 (exact to the constants used). The inverse is km² = acres × 4,046.8564224 ÷ 1,000,000.
Which acre does this converter use-international or U.S. survey?
This tool uses the international acre (exactly 4,046.8564224 m²), which is standard for modern land, agriculture, and real-estate work worldwide. The U.S. survey acre differs by only a few parts per million and mainly matters for legacy geodetic projects; for planning and reporting, the international acre is appropriate.
Should I store land area in km², hectares, acres, or m²?
Use a single canonical unit for storage and analytics-most teams choose square meters (m²). Render km² for regional summaries, hectares for fields, and acres for U.S.-facing audiences. Converting at the edges and rounding once at presentation keeps PDFs, emails, maps, and CSV exports identical.
How should I round km² ↔ acres for public dashboards and legal reports?
Compute with full precision and round once at output. For public pages, 2–3 decimals in acres or hectares reads cleanly; for permits or survey annexes, follow your measurement method and governing standard. Publish one rounding policy and apply it consistently across all surfaces.
Do map projections affect these unit factors?
Unit factors are definitions and never change. Projections affect how you *calculate* the polygon’s area from coordinates. Once you have an area in m² or km², converting to acres is a pure unit step that uses exact constants.
What are common mistakes when converting large land areas?
Frequent pitfalls include using rounded factors (e.g., 1 km² ≈ 247.11 ac) in intermediate steps, mixing the survey acre with the international acre, and double-rounding in different layers (map → CSV → report). Keep one source of truth (m²), convert once on render, and document your constants.
How do km² relate to hectares and square miles?
1 km² = 100 hectares (ha) exactly; 1 mi² ≈ 2.58999 km². Since 1 ha = 10,000 m² and 1 acre = 4,046.8564224 m², you can bridge between ha and acres precisely: 1 ha ≈ 2.47105381467165 acres.
What field names and documentation prevent confusion across teams?
Use explicit columns like area_m2, area_km2, area_ha, and area_ac. Add a short methods note: “Exact constants: 1 acre = 4,046.8564224 m²; 1 km² = 1,000,000 m²; round once at presentation.” This prevents silent drift and off-by-factor mistakes.
Tips for Working with km² & acres
- Keep m² canonical; derive km², ha, and acres for UI.
- Round once at output; avoid re-rounding during exports and report generation.
- Use explicit unit columns (area_m2, area_km2, area_ha, area_ac) and publish constants in your docs.
- Maintain regression pairs (e.g., 1 km² ↔ 247.105381467165 ac; 0.40468564 km² ↔ 100 ac) and assert both directions in tests.