Square Millimeters to Rai (Thai) (mm² to rai)

1 square millimeter equals 6.25×10⁻¹⁰ rai (Thai) exactly.

1 square millimeter = 6.25×10⁻¹⁰ rai (Thai)

How to convert square millimeters to rai (Thai)

To convert square millimeters to rai (Thai), multiply the number of square millimeters by 6.25×10⁻¹⁰. This factor is exact. To go the other way, multiply rai (Thai) by 1,600,000,000.

rai (Thai) = square millimeters × 6.25×10⁻¹⁰

Example: 10 square millimeters = 6.25×10⁻⁹ rai (Thai).

About these units

Square Millimeter (mm²)

Metric (SI)Current unit

A square one millimeter on a side. Used for the cross-section of wires and small parts.

Gauss gets the credit for putting the millimeter at the base of a scientific measuring system. His 1832 proposal for absolute units used the millimeter, milligram and second, although the centimeter-based CGS system later won out among scientists. The square millimeter is a one-thousandth-by-one-thousandth square of a meter, so it takes a million of them to make a square meter, and it has no famous inventor of its own.

Electricians know it best. Wire and cable sizes are given as the cross-sectional area of the copper conductor, and the standard sizes listed for UK domestic wiring are 1, 1.5, 2.5, 4, 6 and 10 mm². Twin and earth cable of 2.5 mm² typically serves sockets on a 16 A radial or 32 A ring circuit, 1 mm² serves lighting on a 6 A breaker, and 4 mm² feeds a cooker or shower. Conductor size depends on current capacity and allowed voltage drop, not on voltage alone. One square inch is exactly 645.16 mm², so small parts in either system compare easily.

1 square millimeter = 0.000001 square meters (exactly).

Sources: Wikipedia: Electrical wiring in the United Kingdom; Wikipedia: Centimetre-gram-second system of units; Wikipedia: Square metre

Rai (Thai) (rai)

ThaiTraditional unit (still used in some regions)

Exactly 1,600 m² (about 0.4 acre). The standard unit of land in Thailand.

Rai is a Thai word for a field or plantation, and it is the standard unit for farmland and rural property in Thailand. One rai is the area of a square one sen on each side, which with a sen of 40 m gives 1,600 square meters, or 16 ares.

That is roughly 0.4 acre, so a hectare holds 6.25 rai. The rai is divided into 4 ngan and 400 square wa, and official land documents record areas in these three tiers, sometimes in shorthand such as 4-2-25 for 4 rai, 2 ngan and 25 square wa.

Older land measures in the region were looser, but the cadastral survey started in 1896 fixed the units against metric lengths. The rai is therefore exact today, and it is still the unit in which Thai land is bought, sold and taxed.

1 rai (Thai) = 1,600 square meters (exactly).

Sources: Wikipedia: Rai (unit); Wikipedia: Thai units of measurement

Related conversions

See all area units.