Convert Square Thou to Square Mil
Convert square thous to square mils instantly. 1 square thou = 1 square mil — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Square Mil 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 Mil
A square mil is an imperial unit of area equal to 6.4516×10⁻¹⁰ m². It is widely used in printed circuit board (PCB) design and electronics manufacturing.
Derived by squaring the mil (1 mil = 1/1000 of an inch = 0.0254 mm). Standardized via the 1959 International Yard and Pound Agreement.
Square mils are the standard unit for PCB trace cross-sections, pad areas, and component pitches in US-localized electronic design software and datasheets.
Standardized via the 1959 International Yard and Pound Agreement.
Square Thou to Square Mil conversion formula
The relationship between square thous and square mils:
To convert square thous to square mils, multiply the value in square thous by 1. To reverse, multiply square mils by 1.
How to use this converter
Type a value into the calculator. The result in square mils 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 Mil to Square Thou converter for the reverse direction.
Step-by-step: convert square thous to square mils
- Write down the value in square thous (thou²).
- Multiply that value by the factor 1.
- The product is the equivalent value in square mils (mil²).
- To reverse, multiply the square mil value by 1.
Worked examples
Example 1 — Convert 1 thou² to mil²:
1 × 1 = 1 mil²
Example 2 — Convert 100 thou² to mil²:
100 × 1 = 100 mil²
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 × 1 = 2 mil²
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 mils for direct comparison with another instrument's calibration data sheet.
800 thou² × 1 = 800 mil²
Square Thou to Square Mil conversion table
Standard reference values for converting square thous to square mils:
| Square Thou [thou²] | Square Mil [mil²] |
|---|---|
| 0.01 | 0.01 |
| 0.1 | 0.1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
| 10 | 10 |
| 20 | 20 |
| 30 | 30 |
| 40 | 40 |
| 50 | 50 |
| 100 | 100 |
| 500 | 500 |
| 1000 | 1000 |
Frequently asked questions
How many square mils is 1 square thou?
How do I convert square thous to square mils?
How do I convert square mils back to square thous?
How many square mils is 100 square thous?
Popular area unit conversions
Convert Square Thou to other area units
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Metric / SI (5 units)
Imperial / US Customary (14 units)
Sources & references
Conversion factor (1 thou² = 1 mil²) 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.