Convert Fermi to Bohr Radius
Convert fermis to bohr radii instantly. 1 fermi = 1.889726e-5 bohr radius — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Bohr Radius to Fermi converter for the reverse conversion.
Units explained
Fermi
A fermi is a unit of length equal to one femtometer (1×10⁻¹⁵ m). It is named after physicist Enrico Fermi and is widely used in nuclear physics as a synonym for the femtometer.
The fermi was introduced informally in mid-20th-century nuclear physics literature. Although the BIPM has formally standardised the SI name 'femtometer', the fermi remains in widespread informal use.
Fermis are used to express nuclear sizes, hadron radii, and characteristic length scales in particle physics. Functionally identical to the femtometer.
Named after Enrico Fermi; in informal use from the 1950s; officially equivalent to the SI femtometer.
Bohr Radius
The Bohr radius is approximately 5.292×10⁻¹¹ meters — the most probable distance between the proton and electron in a hydrogen atom in its ground state.
Defined by Niels Bohr in his 1913 model of the hydrogen atom. The current CODATA 2018 value of 5.29177210903×10⁻¹¹ m is derived from the elementary charge, electron mass, and Planck's constant.
The Bohr radius is used throughout atomic physics, quantum chemistry, and computational chemistry as the natural length scale for electronic-structure calculations. The atomic unit (a.u.) of length equals the Bohr radius.
Defined by Bohr in 1913; current value via CODATA 2018.
Fermi to Bohr Radius conversion formula
The relationship between fermis and bohr radii:
To convert fermis to bohr radii, multiply the value in fermis by 1.889726e-5. To reverse, multiply bohr radii by 52917.7210903.
How to use this converter
Type a value into the calculator. The result in bohr radii updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Bohr Radius to Fermi converter for the reverse direction.
Step-by-step: convert fermis to bohr radii
- Write down the value in fermis (F).
- Multiply that value by the factor 1.889726e-5.
- The product is the equivalent value in bohr radii (a₀).
- To reverse, multiply the bohr radius value by 52917.7210903.
Worked examples
Example 1 — Convert 1 F to a₀:
1 × 1.889726e-5 = 1.889726e-5 a₀
Example 2 — Convert 100 F to a₀:
100 × 1.889726e-5 = 0.0018897261 a₀
Real-world example — Molecular dimensions
The diameter of small molecular structures (around 2 fermis) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.
2 F × 1.889726e-5 = 3.779452e-5 a₀
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 fermis can be re-expressed in bohr radii for direct comparison with another instrument's calibration data sheet.
800 F × 1.889726e-5 = 0.015117809 a₀
Fermi to Bohr Radius conversion table
Standard reference values for converting fermis to bohr radii:
| Fermi [F] | Bohr Radius [a₀] |
|---|---|
| 0.01 | 1.889726e-7 |
| 0.1 | 1.889726e-6 |
| 1 | 1.889726e-5 |
| 2 | 3.779452e-5 |
| 3 | 5.669178e-5 |
| 4 | 7.558904e-5 |
| 5 | 9.448631e-5 |
| 10 | 0.0001889726 |
| 20 | 0.0003779452 |
| 30 | 0.0005669178 |
| 40 | 0.0007558904 |
| 50 | 0.0009448631 |
| 100 | 0.0018897261 |
| 500 | 0.0094486306 |
| 1000 | 0.0188972612 |
Frequently asked questions
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Sources & references
Conversion factor (1 F = 1.889726e-5 a₀) 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.