Convert Square Thou to Square Microinch
Convert square thous to square microinches instantly. 1 square thou = 999999.9999999999 square microinch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Square Microinch to Square Thou converter for the reverse conversion.
Units explained
Square Thou
A square thou is an imperial unit of area equal to 6.4516×10⁻¹⁰ m², identical to the square mil. The word 'thou' is short for 'thousandth' (of an inch).
Identical in value to the square mil; 'thou' is the British engineering term, 'mil' is the American term. Both refer to 1/1000 of an inch.
Square thous are used in British and Commonwealth engineering contexts where 'thou' is preferred over 'mil', particularly in mechanical engineering tolerance specifications.
Standardized via the 1959 International Yard and Pound Agreement.
Square Microinch
A square microinch is an imperial unit of area equal to 6.4516×10⁻¹⁶ m². It is used in precision-engineering contexts where surface roughness is measured in microinches.
Derived by squaring the microinch (1 µin = 25.4 nm). Standardized via the 1959 International Yard and Pound Agreement which defined 1 inch = 25.4 mm exactly.
Square microinches appear in surface metrology and high-precision manufacturing in countries that use imperial units, though more often surface roughness is reported as a length parameter (Ra) rather than as an area.
Standardized via the 1959 International Yard and Pound Agreement.
Square Thou to Square Microinch conversion formula
The relationship between square thous and square microinches:
To convert square thous to square microinches, multiply the value in square thous by 999999.9999999999. To reverse, multiply square microinches by 1e-6.
How to use this converter
Type a value into the calculator. The result in square microinches updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Square Microinch to Square Thou converter for the reverse direction.
Step-by-step: convert square thous to square microinches
- Write down the value in square thous (thou²).
- Multiply that value by the factor 999999.9999999999.
- The product is the equivalent value in square microinches (µin²).
- To reverse, multiply the square microinch value by 1e-6.
Worked examples
Example 1 — Convert 1 thou² to µin²:
1 × 999999.9999999999 = 999999.9999999999 µin²
Example 2 — Convert 100 thou² to µin²:
100 × 999999.9999999999 = 1e+8 µin²
Real-world example — Molecular dimensions
The diameter of small molecular structures (around 2 square thous) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.
2 thou² × 999999.9999999999 = 1999999.9999999998 µin²
Real-world example — Wavelengths across the spectrum
Optical and atomic-scale phenomena are routinely cross-converted between sub-micron units. A photon of wavelength 800 square thous can be re-expressed in square microinches for direct comparison with another instrument's calibration data sheet.
800 thou² × 999999.9999999999 = 8e+8 µin²
Square Thou to Square Microinch conversion table
Standard reference values for converting square thous to square microinches:
| Square Thou [thou²] | Square Microinch [µin²] |
|---|---|
| 0.01 | 10000 |
| 0.1 | 100000 |
| 1 | 999999.9999999999 |
| 2 | 1999999.9999999998 |
| 3 | 2999999.9999999995 |
| 4 | 3999999.9999999995 |
| 5 | 4999999.9999999991 |
| 10 | 9999999.9999999981 |
| 20 | 2e+7 |
| 30 | 3e+7 |
| 40 | 4e+7 |
| 50 | 5e+7 |
| 100 | 1e+8 |
| 500 | 5e+8 |
| 1000 | 1e+9 |
Frequently asked questions
How many square microinches is 1 square thou?
How do I convert square thous to square microinches?
How do I convert square microinches back to square thous?
How many square microinches is 100 square thous?
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Metric / SI (5 units)
Imperial / US Customary (14 units)
Sources & references
Conversion factor (1 thou² = 999999.9999999999 µin²) 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.