Convert Square Millimeter to Rai (mm² → rai)

Converting square millimeters to rais is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in square millimeters

   Start with the number of square millimeters (mm²) you want to convert.
2. 2
   Multiply by 6.25 × 10^-10

   The conversion factor from mm² to rai is 6.25 × 10^-10. Multiply your value by this number.
3. 3
   Read the result in rais

   The result is your value in rais (rai).

Multiply the value in square millimeters by 6.25 × 10^-10. For the reverse direction, multiply by 1,600,000,000.

• ✓1 mm² = 0.01 cm² = 10⁻⁶ m².
• ✓Electrical cables: 1 mm² up to 10 A; 2.5 mm² up to 16 A (EU standards).
• ✓Always convert to m² for large structures; mm² for precision parts.

• ✗Using mm² instead of cm² for medium-sized surfaces — clutters figures.
• ✗Confusing mm² with mm — different dimensions.
• ✗Assuming a cable rated at 1.5 mm² is 1.5 mm wide — it is the conductive cross-section.

What is the Square Millimeter?

The square millimeter equals one millionth of a square meter (10⁻⁶ m²) and is the precision area unit for electronics, microfabrication, mechanical engineering, and component cross-sections. Wire gauges in electronics specify cross-sectional area in mm² (a 2.5 mm² wire is standard for household lighting circuits). Computer chip die sizes and printed circuit board footprints are measured in mm². The square millimeter relates to the square centimeter (100 mm² = 1 cm²), the square meter (1,000,000 mm² = 1 m²), and the square inch (1 mm² ≈ 0.00155 in²). Engineering tolerances, microscope-image areas, and laser-spot sizes all use this scale. The square millimeter is critical in stress calculations: pressure (N/mm²) and strength (MPa) calculations in mechanical engineering routinely use this unit.

• Electrical cable cross-section (e.g. 2.5 mm² copper)
• Microelectronics and semiconductor areas
• Pharmaceutical tablet surface areas

What is the Rai?

The rai equals exactly 1,600 square meters (40 m × 40 m) and is the traditional Thai land unit, still officially used in Thailand for real estate, agriculture, and property records. The rai is divided into 4 ngan (each 400 m²), and 1 ngan equals 100 wa (each 4 m²). Despite Thailand's adoption of the metric system, the rai remains the everyday unit for buying and selling land in Thai contexts — a small urban plot might be 1 rai, while rural farms are quoted in tens or hundreds of rai. The rai relates to the square meter (1 rai = 1,600 m²), the hectare (1 ha = 6.25 rai), and the acre (1 acre ≈ 2.529 rai). The rai's exact metric definition (1,600 m²) makes conversion to SI units precise, unlike many traditional land units.

• Thai rural property and farmland
• Thai real-estate listings
• Agricultural yield reporting in Thailand