Convert Planck Length to Fermi
Convert planck lengths to fermis instantly. 1 planck length = 1.616255e-20 fermi — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Fermi to Planck Length converter for the reverse conversion.
Units explained
Planck Length
The Planck length is approximately 1.616×10⁻³⁵ meters — the natural unit of length in Planck's system of natural units. It is constructed from the gravitational constant, the speed of light, and the reduced Planck constant.
Defined by Max Planck in 1899 as part of a natural unit system independent of any human or planetary reference. The current CODATA 2018 value is 1.616255×10⁻³⁵ m, derived from G, ℏ, and c.
The Planck length appears in quantum-gravity research and string theory as the scale at which classical notions of spacetime are expected to break down. It is not measurable directly with current technology.
Defined by Planck in 1899; value derived from fundamental constants, most recently updated by CODATA 2018.
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.
Planck Length to Fermi conversion formula
The relationship between planck lengths and fermis:
To convert planck lengths to fermis, multiply the value in planck lengths by 1.616255e-20. To reverse, multiply fermis by 6.187142e+19.
How to use this converter
Type a value into the calculator. The result in fermis updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Fermi to Planck Length converter for the reverse direction.
Step-by-step: convert planck lengths to fermis
- Write down the value in planck lengths (ℓP).
- Multiply that value by the factor 1.616255e-20.
- The product is the equivalent value in fermis (F).
- To reverse, multiply the fermi value by 6.187142e+19.
Worked examples
Example 1 — Convert 1 ℓP to F:
1 × 1.616255e-20 = 1.616255e-20 F
Example 2 — Convert 100 ℓP to F:
100 × 1.616255e-20 = 1.616255e-18 F
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 planck lengths can be re-expressed in fermis for direct comparison with another instrument's calibration data sheet.
800 ℓP × 1.616255e-20 = 1.293004e-17 F
Real-world example — Molecular dimensions
The diameter of small molecular structures (around 2 planck lengths) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.
2 ℓP × 1.616255e-20 = 3.23251e-20 F
Planck Length to Fermi conversion table
Standard reference values for converting planck lengths to fermis:
| Planck Length [ℓP] | Fermi [F] |
|---|---|
| 0.01 | 1.616255e-22 |
| 0.1 | 1.616255e-21 |
| 1 | 1.616255e-20 |
| 2 | 3.23251e-20 |
| 3 | 4.848765e-20 |
| 4 | 6.46502e-20 |
| 5 | 8.081275e-20 |
| 10 | 1.616255e-19 |
| 20 | 3.23251e-19 |
| 30 | 4.848765e-19 |
| 40 | 6.46502e-19 |
| 50 | 8.081275e-19 |
| 100 | 1.616255e-18 |
| 500 | 8.081275e-18 |
| 1000 | 1.616255e-17 |
Frequently asked questions
How many fermis is 1 planck length?
How do I convert planck lengths to fermis?
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How many fermis is 100 planck lengths?
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Sources & references
Conversion factor (1 ℓP = 1.616255e-20 F) 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 Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.