Hectares to Acres Converter — Convert ha to ac (Exact: 1 ha = 2.4710538147 acres)
Accurate hectares (ha) to acres (ac) converter derived from exact definitions: 1 hectare = 10,000 m² and 1 acre = 4046.8564224 m². Ideal for land sales, farm management, cadastral mapping, GIS, planning approvals, forestry, and conservation reporting. Includes precise formulas, step-by-step examples, expanded reference tables, and in-depth FAQs.
Exact bases: 1 ha = 10,000 m², 1 ac = 4046.8564224 m² ⇒ ac = ha × 2.4710538147…. Explore all area metric conversion calculators.
About Hectares to Acres Conversion
The hectare (ha) is the international workhorse for land area: a clean SI-compatible square of 100 m by 100 m (10,000 m²). It is standard across agriculture, forestry, ecology, and government statistics. The acre (ac), defined as 43,560 square feet, remains common in real-estate listings, deeds, and ranching across the US. Converting hectares to acres lets you publish figures in the unit your audience expects without sacrificing SI fidelity for analytics and compliance.
Because both units are derived from exact definitions (meter and international foot), the factor 1 ha = 2.4710538147 ac is exact. Keep full precision internally and round once when you display or export so parcel sheets, PDFs, and CSVs remain in sync.
A reliable approach is to store area_m2 or area_ha canonically, derive acres for US-facing documents, and include a short methods note with constants and rounding policy. This prevents silent drift when multiple teams and vendors exchange data.
Hectares to Acres Formula
Exact relationship
Use either expression:
ac = ha × 2.4710538146717
// inverse
ha = ac × 0.40468564224Example:
3.2 ha × 2.4710538146717 = 7.90737 acRelated Area Converters
What is a Hectare (ha)?
A hectare equals 10,000 square meters—one square hectometer (100 m × 100 m). The size is convenient for farm fields, forest compartments, habitat plots, and park planning. Because it’s built from meters, a hectare integrates naturally with GIS layers (m, km, m²), agronomic calculations, and environmental indicators (e.g., tCO₂e/ha).
What is an Acre (ac)?
An acre is a customary land unit fixed at 43,560 square feet. Using the international foot (0.3048 m exactly), one acre is exactly 4046.8564224 m². It remains the preferred headline unit for ranches, listings, and zoning summaries in the US, even when the underlying analytics are metric.
Step-by-Step: Converting ha to ac
- Read the land area in hectares (ha) from your GIS attribute or document.
- Multiply by 2.4710538147… to convert to acres (ac).
- Round once at presentation based on your policy (e.g., 2 decimals for listings; 3–4 for audits).
Example walkthrough:
Input: 12.75 ha
Compute: 12.75 × 2.4710538146717 = 31.51194 ac
Output: 31.51 ac (UI, 2 decimals)Common Conversions
Everyday quick checks (ha → ac)
| ha | ac | ha | ac |
|---|---|---|---|
| 0.1 | 0.24710538 | 0.25 | 0.61776345 |
| 0.5 | 1.23552691 | 1 | 2.47105381 |
| 2 | 4.94210763 | 5 | 12.35526907 |
| 10 | 24.71053815 | 100 | 247.10538147 |
Precision, Rounding & Significant Figures
Operational rounding
For marketing and portals, acres to 2 decimals and hectares to 3 decimals are common. For cadastral reconciliation or program compliance, retain more decimals or store square meters alongside. Always round once at presentation to keep deeds, maps, invoices, and dashboards synchronized.
Consistent documentation
Adopt explicit field names—area_ha, area_ac, area_m2—and publish a methods note: “Exact: 1 ha = 10,000 m²; 1 ac = 4046.8564224 m²; ac = ha × 2.4710538147…; round once on output.” Consistency prevents confusion across teams, vendors, and exports.
Where This Converter Is Used
- 🌾 Agriculture & farm management: Field sizes in hectares with buyer-friendly acres in brochures.
- 🌲 Forestry & conservation: Compartment areas, restoration plots, and registry submissions.
- 🗺️ GIS & planning: Zoning summaries, environmental impact assessments, and public notices.
- 🏡 Real estate & auctions: International catalogs that show both ha and ac for clarity.
- 🏛️ Government statistics: Land-use surveys and agricultural censuses standardized in hectares.
Quick Reference Table
Acres to hectares (ac → ha)
| ac | ha | ac | ha |
|---|---|---|---|
| 0.25 | 0.10117141 | 0.5 | 0.20234282 |
| 1 | 0.40468564 | 2 | 0.80937128 |
| 5 | 2.02342821 | 10 | 4.04685642 |
| 20 | 8.09371284 | 50 | 20.23428211 |
| 100 | 40.46856422 | 1000 | 404.68564224 |
Frequently Asked Questions
What is the exact formula to convert hectares to acres?
Begin with exact bases: 1 hectare = 10,000 m² and 1 acre = 4046.8564224 m² (from 43,560 ft² with 1 ft = 0.3048 m). Therefore acres = hectares × (10,000 ÷ 4046.8564224) = hectares × 2.4710538147…. The inverse is hectares = acres × 0.40468564224. Because these constants are exact, your results are reproducible across GIS, spreadsheets, and deeds.
Why do many datasets store hectares instead of acres?
Hectares are SI-compatible (10,000 m²), so they integrate cleanly with metric layers in GIS, agronomy models, and environmental reporting. Many systems store m² or ha as canonical and derive acres for US-facing reports. This avoids mixing units and keeps analytics consistent across borders.
How should I round hectares ↔ acres for listings, audits, and permits?
Compute with full precision and round once at presentation. Listings often show acres to 2 decimals and hectares to 3 decimals; scientific and regulatory programs may require 3–4 decimals or square meters in backups. Publish your rounding policy so PDFs, CSV exports, and dashboards always match.
Does terrain slope change the conversion from ha to ac?
No. This is a pure unit conversion between planimetric area measures. If you need surface area over sloped terrain, compute that in GIS with a terrain model first. Once an area value is determined, the unit conversion (ha ↔ ac) is the same.
What about the US survey foot—does it affect acre size?
Modern practice uses the international foot (exactly 0.3048 m). Historic survey-foot projects differ by ~2 ppm, shifting one acre by ~0.008 m²—negligible for most workflows. Unless a legacy survey explicitly requires it, use the international definitions employed here.
Can I sum parcels that are in mixed units (some in ha, some in ac)?
Avoid mixing units in a single column. Normalize all areas to a canonical unit (ha or m²), perform math and analytics there, then convert for display. Mixed-unit columns are a top source of audit discrepancies and off-by-percentage errors.
How can I regression-test my conversion pipeline?
Maintain a short set of known pairs—e.g., 1 ha = 2.4710538147 ac; 10 ha = 24.710538147 ac; 1 ac = 0.40468564224 ha—and assert both directions in CI. This catches accidental constant edits and double-rounding across layers.
Tips for Working with Hectares & Acres
- Keep SI (m²/ha) canonical for analytics and compliance; compute acres for regional display.
- Normalize units on write; convert on read. Never mix ha and ac in the same numeric column.
- Document constants and rounding once, and reuse across PDFs, emails, and CSV exports.