Convert Square Millimeter to Chō
Convert square millimeters to chōs instantly. 1 square millimeter = 1.008333e-10 chō — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Chō to Square Millimeter converter for the reverse conversion.
Units explained
Square Millimeter
A square millimeter is a metric unit of area equal to 10⁻⁶ m² (1 mm × 1 mm). It is widely used in engineering, electronics, and small-scale technical work.
Derived by squaring the millimeter, defined as 1/1000 of a meter. The milli- prefix comes from the Latin 'mille' (thousand).
Square millimeters express PCB trace cross-sections, the area of small mechanical features in CAD drawings, biological sample sizes, and material thicknesses.
Millimeter has been part of the metric system since 1795.
Chō
A chō is a Japanese unit of large-scale area equal to approximately 9917.36 m² (about 0.991 hectare or 2.45 acres). It equals 3,000 tsubo.
Traditional Japanese land area unit, used historically for rice paddies and large estates.
Chōs appear in Japanese agricultural records and historical land documents. Modern usage favors hectares for new transactions but legacy records remain.
Traditional Japanese unit; standardized via the tsubo definition.
Square Millimeter to Chō conversion formula
The relationship between square millimeters and chōs:
To convert square millimeters to chōs, multiply the value in square millimeters by 1.008333e-10. To reverse, multiply chōs by 9.91736e+9.
How to use this converter
Type a value into the calculator. The result in chōs updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Chō to Square Millimeter converter for the reverse direction.
Step-by-step: convert square millimeters to chōs
- Write down the value in square millimeters (mm²).
- Multiply that value by the factor 1.008333e-10.
- The product is the equivalent value in chōs (chō).
- To reverse, multiply the chō value by 9.91736e+9.
Worked examples
Example 1 — Convert 1 mm² to chō:
1 × 1.008333e-10 = 1.008333e-10 chō
Example 2 — Convert 100 mm² to chō:
100 × 1.008333e-10 = 1.008333e-8 chō
Real-world example — Feature-scale to long-haul
One billion square millimeters equals exactly one chō — the conversion an optical-network engineer performs when totalling feature-level path lengths into a single long-haul fiber-link distance.
1e+9 mm² × 1.008333e-10 = 0.1008332863 chō
Real-world example — Fiber-optic link lengths
Converting from microscale square millimeters to the chōs of a long-haul fiber link is the conversion an optical engineer performs when calculating attenuation per kilometre of fiber.
1e+9 mm² × 1.008333e-10 = 0.1008332863 chō
Square Millimeter to Chō conversion table
Standard reference values for converting square millimeters to chōs:
| Square Millimeter [mm²] | Chō [chō] |
|---|---|
| 0.01 | 1.008333e-12 |
| 0.1 | 1.008333e-11 |
| 1 | 1.008333e-10 |
| 2 | 2.016666e-10 |
| 3 | 3.024999e-10 |
| 4 | 4.033331e-10 |
| 5 | 5.041664e-10 |
| 10 | 1.008333e-9 |
| 20 | 2.016666e-9 |
| 30 | 3.024999e-9 |
| 40 | 4.033331e-9 |
| 50 | 5.041664e-9 |
| 100 | 1.008333e-8 |
| 500 | 5.041664e-8 |
| 1000 | 1.008333e-7 |
Frequently asked questions
How many chōs is 1 square millimeter?
How do I convert square millimeters to chōs?
How do I convert chōs back to square millimeters?
How many chōs is 100 square millimeters?
Popular area unit conversions
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Metric / SI (15 units)
Imperial / US Customary (15 units)
US Survey (5 units)
Indian Subcontinent (16 units)
Other Regional (10 units)
Scientific / Physics (5 units)
Sources & references
Conversion factor (1 mm² = 1.008333e-10 chō) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.