Acres to Hectares Converter — Convert ac to ha (Exact: 1 acre = 0.40468564224 ha)
Accurate acres (ac) to hectares (ha) converter using exact definitions: 1 acre = 43,560 ft² and 1 ft = 0.3048 m ⇒ 1 acre = 4046.8564224 m² = 0.40468564224 ha. Built for land sales, farm management, cadastral mapping, GIS, planning approvals, and environmental reporting. Includes precise formulas, worked examples, expanded reference tables, and in-depth FAQs.
Exact bases: 1 acre = 43,560 ft², 1 ft = 0.3048 m ⇒ 1 acre = 4046.8564224 m² ⇒ ha = acres × 0.40468564224. Browse all free area unit converters.
About Acres to Hectares Conversion
The acre (ac) dominates land descriptions in the United States and parts of Canada for listings, deeds, and property tax rolls. The hectare (ha) is the international standard in agriculture, forestry, environmental reporting, and planning approvals. Converting acres to hectares lets you publish one set of figures that satisfies local expectations while keeping SI-compliant analytics.
Because the definitions are exact—1 ft = 0.3048 m, 1 acre = 43,560 ft², and 1 hectare = 10,000 m²—the conversion ha = acres × 0.40468564224 is exact as well. Keep full precision in your pipeline and round once on output so plats, spreadsheets, and disclosures agree everywhere they appear.
A common data model stores area_m2 or area_ha as canonical and computes acres for US-facing documents. Use explicit unit-suffixed field names and a short methods note to prevent confusion across teams and vendors.
Acres to Hectares Formula
Exact relationship
Use either expression:
ha = acres × 0.40468564224
// inverse
acres = ha × 2.4710538146717Example:
10 ac × 0.40468564224 = 4.0468564224 haRelated Area Converters
What is an Acre (ac)?
The acre is a customary land unit equal to 43,560 square feet. Historically it was standardized via survey measures (1 chain × 1 furlong). Using the international foot makes its metric equivalent exact: 1 acre = 4046.8564224 m². Acres are common in property listings, ranch operations, and zoning summaries in the US.
What is a Hectare (ha)?
A hectare is an SI-compatible unit defined as 10,000 square meters—a square of 100 m by 100 m. It’s the default unit for farm sizes, forestry compartments, wildlife habitat metrics, and many national statistics offices. Because it integrates cleanly with meters, hectares simplify GIS analysis, yield calculations, and environmental modeling.
Step-by-Step: Converting ac to ha
- Read the land area in acres (ac) from a deed, listing, or GIS attribute.
- Multiply by 0.40468564224 to convert to hectares (ha).
- Round once at presentation per your policy (e.g., ha to 3 d.p. for reports; 2 d.p. for listing portals).
Example walkthrough:
Input: 2.75 ac
Compute: 2.75 × 0.40468564224 = 1.11388556516 ha
Output: 1.114 ha (UI, 3 decimals)Common Conversions
Everyday quick checks (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 |
Precision, Rounding & Significant Figures
Operational rounding
For listings and PR, acres to 2 d.p. and hectares to 3 d.p. strike a good balance. For cadastral reconciliation or program compliance, carry more decimals or use square meters in backups. Store exact values; round once on output so deeds, maps, and statements stay in sync.
Consistent documentation
Standardize field names (e.g., area_ac, area_ha, area_m2). Publish a short methods note: “Exact: 1 ac = 4046.8564224 m²; 1 ha = 10,000 m²; ha = ac × 0.40468564224. Round once at presentation.” Consistency prevents confusion when multiple teams collaborate across regions.
Where This Converter Is Used
- 🏡 Real estate & land sales: Present parcels in acres for local buyers and hectares for international marketing.
- 🌾 Agriculture & farm management: Field sizes, yields per hectare, and input planning (seed, fertilizer, irrigation).
- 🗺️ GIS & planning: Zoning summaries, environmental impact assessments, and protected area metrics in ha.
- 🌲 Forestry: Compartment inventories, thinning areas, and annual allowable cuts reported in hectares.
- 🌿 Conservation & carbon projects: Restoration and afforestation areas, monitoring plots, and registry submissions.
Quick Reference Table
Hectares to acres (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 |
Frequently Asked Questions
What is the exact formula to convert acres to hectares?
Start from the exact bases: 1 acre = 43,560 ft² and 1 ft = 0.3048 m. Therefore 1 acre = 43,560 × (0.3048 m)² = 4046.8564224 m². A hectare is exactly 10,000 m². Hence ha = acres × 4046.8564224 ÷ 10,000 = acres × 0.40468564224. The inverse is acres = ha ÷ 0.40468564224 ≈ ha × 2.4710538147. These are exact relationships derived from the international foot.
Why do area conversions use squared length factors?
Area is two-dimensional. A linear change from feet to meters multiplies by 0.3048, so area must use (0.3048)² = 0.09290304 when moving from ft² to m². Because the acre is defined from square feet, its square-meter value is exact and so is the acre ↔ hectare factor.
How should I round for deeds, listings, and regulatory forms?
Retain full precision internally and round once at the presentation layer. Real-estate listings often use 2 decimals for acres and 3 decimals for hectares. Environmental and agricultural reporting may require 3–4 decimals depending on program rules. Publish the rounding policy—e.g., “store exact; display ha to 3 d.p.”—to avoid discrepancies across PDFs and exports.
Does the US survey foot change the value of an acre?
Modern workflows use the international foot (exactly 0.3048 m). Historic US survey-foot projects differ by ~2 ppm, which shifts one acre by about 0.008 m²—negligible for most applications. Unless a legacy survey explicitly requires it, use the international definitions used on this page.
What is a hectare and why is it common outside the US?
A hectare (ha) is exactly 10,000 m²—one square hectometer (100 m × 100 m). It is the standard land unit in agriculture, forestry, environmental reporting, and planning across most of the world because it integrates cleanly with SI units and GIS systems.
Can I add parcels listed in acres and hectares in one column?
Avoid mixing units in the same field. Normalize to a canonical unit (many GIS databases and planning tools choose hectares or square meters), perform sums and analytics there, and convert for display. Mixed-unit columns are a frequent source of audit errors.
What precision should I use for small plots vs. large ranches?
For small urban lots, show more decimals (e.g., acres to 3 d.p. or hectares to 4 d.p.). For very large tracts, fewer decimals keep reports readable. Always keep raw values exact and round once on output to ensure invoices, plats, and dashboards match.
How do I validate my conversion pipeline?
Maintain a short regression set of pairs—e.g., 1 ac = 0.40468564224 ha; 10 ac = 4.0468564224 ha; 1 ha = 2.4710538147 ac—and assert both directions in CI. This catches accidental constant changes and rounding twice in different layers.
Where does the 43,560 ft² definition come from?
An acre was historically defined as 1 chain (66 ft) by 1 furlong (660 ft), yielding 66 × 660 = 43,560 ft². With the international foot fixed at exactly 0.3048 m, the acre’s metric equivalent becomes exact as well.
Do I need density or elevation data for this conversion?
No. This is a pure unit conversion between area measures. Terrain slope, vertical datum, or density are unrelated. If you need surface area over terrain (plan vs. surface), use GIS tools; the unit conversion remains the same.
Tips for Working with Acres & Hectares
- Keep SI (m²/ha) canonical for analytics and compliance; compute acres for regional display.
- Avoid mixing units in one column; normalize on write and convert on read.
- Document your rounding policy and exact constants in a short “Methods” note shared across teams.