Acres to Hectares

Land Surveying & NIST SP 811 Standards

The National Institute of Standards and Technology (NIST SP 811) defines exact legal conversion factors for agricultural and cadastral land measurement.

Primary Land Area Conversion Factors

• 1 Acre: 0.40468564224 Hectares = 43,560 sq ft = 4,046.86 m^2 = (1) / (640) sq mi

• 1 Hectare: 2.47105381467 Acres = 10,000 m^2 = 107,639.1 sq ft

• 1 Square Mile (Section): 640 Acres = 258.9988 Hectares

• Acres to Hectares Formula: ha = Acres × 0.4046856

• Hectares to Acres Formula: Acres = Hectares × 2.471054

How to Use This Calculator

Enter your Land Area to Convert (e.g. 50.0) and Conversion Direction — choose from Acres to Hectares (ac → ha), Hectares to Acres (ha → ac). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Conversion factors used in this calculator:

1 Acre = 0.40468564224 Hectares

1 Hectare = 2.47105381467 Acres

Worked Example

A 50-acre farm in North America occupies 20.23 hectares of farmland, spanning 2.18 million square feet.

Understanding Your Result

Unit conversion precision: round to the same number of significant figures as your original measurement. Converting 6 feet to meters gives 1.8288 m — but if your measurement was approximate (±1 inch), expressing more than 2 decimal places is false precision. For international trade and technical specifications, SI units (meters, kilograms, liters) are the standard. US customary units (feet, pounds, gallons) differ from Imperial UK units: 1 US gallon = 3.785 L vs. 1 UK gallon = 4.546 L.