Convert X-unit to Centimeter
Convert x-units to centimeters instantly. 1 x-unit = 1.0021e-11 centimeter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Centimeter to X-unit converter for the reverse conversion.
Units explained
X-unit
The X-unit (or siegbahn) is a historical X-ray crystallography unit of approximately 1.0021×10⁻¹³ meters. It was used before X-ray wavelengths could be measured directly in meters.
Introduced by Manne Siegbahn in 1925 as a self-consistent unit for X-ray crystallography. The 'X-unit' was defined to make the X-ray wavelength of the molybdenum K-alpha line a round number.
X-units appear in X-ray crystallography literature from 1925 through the 1960s. Modern crystallography uses meters or angstroms; X-units are mostly of historical interest now.
Defined by Manne Siegbahn in 1925; superseded by direct SI measurement of X-ray wavelengths after the 1960s; retained in literature for historical comparison.
Centimeter
A centimeter is a metric unit of length equal to one hundredth of a meter (1/100 m). It is one of the most commonly used SI sub-units in daily life, especially for measuring small objects, body dimensions, paper sizes, and short distances.
The centimeter emerged from the French metric system established by the French Academy of Sciences in 1793. The metric system introduced decimal-based prefixes (milli-, centi-, deci-, deca-, hecto-, kilo-) to create proportional sub-units of the meter.
Centimeters are the standard unit for everyday measurement in nearly every country outside the United States. They are used for body height, clothing sizes, rainfall, paper formats (A4 is 21 × 29.7 cm), screen dimensions, and most consumer product specifications.
Developed in France during the late 18th century as part of the metric system designed by the French Academy of Sciences. Formally adopted in France in 1795 and ratified internationally through the Metre Convention signed in Paris in 1875.
X-unit to Centimeter conversion formula
The relationship between x-units and centimeters:
To convert x-units to centimeters, multiply the value in x-units by 1.0021e-11. To reverse, multiply centimeters by 9.979044e+10.
How to use this converter
Type a value into the calculator. The result in centimeters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Centimeter to X-unit converter for the reverse direction.
Step-by-step: convert x-units to centimeters
- Write down the value in x-units (X).
- Multiply that value by the factor 1.0021e-11.
- The product is the equivalent value in centimeters (cm).
- To reverse, multiply the centimeter value by 9.979044e+10.
Worked examples
Example 1 — Convert 1 X to cm:
1 × 1.0021e-11 = 1.0021e-11 cm
Example 2 — Convert 100 X to cm:
100 × 1.0021e-11 = 1.0021e-9 cm
Real-world example — Sub-micron to millimeter
500,000 x-units converts to a small everyday quantity in centimeters — useful when relating optical-wavelength specifications to physical mounting hardware.
500000 X × 1.0021e-11 = 5.0105e-6 cm
Real-world example — From wavelengths to millimeter-scale objects
A value of one million x-units sounds vast at the atomic scale but converts to a small everyday quantity in centimeters — useful when relating optical-wavelength specifications to physical mounting hardware.
1000000 X × 1.0021e-11 = 1.0021e-5 cm
X-unit to Centimeter conversion table
Standard reference values for converting x-units to centimeters:
| X-unit [X] | Centimeter [cm] |
|---|---|
| 0.01 | 1.0021e-13 |
| 0.1 | 1.0021e-12 |
| 1 | 1.0021e-11 |
| 2 | 2.0042e-11 |
| 3 | 3.0063e-11 |
| 4 | 4.0084e-11 |
| 5 | 5.0105e-11 |
| 10 | 1.0021e-10 |
| 20 | 2.0042e-10 |
| 30 | 3.0063e-10 |
| 40 | 4.0084e-10 |
| 50 | 5.0105e-10 |
| 100 | 1.0021e-9 |
| 500 | 5.0105e-9 |
| 1000 | 1.0021e-8 |
Frequently asked questions
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Sources & references
Conversion factor (1 X = 1.0021e-11 cm) 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.