Convert Fermi to Kilometer
Convert fermis to kilometers instantly. 1 fermi = 1e-18 kilometer — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Kilometer 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.
Kilometer
A kilometer is a metric unit of length equal to one thousand meters. It is the standard unit for measuring road distances, geographic distances, and other large-scale measurements in metric countries.
The kilometer was defined alongside the meter in 1795 using the standard SI prefix kilo- (from Greek chilioi, "thousand"), denoting one thousand units.
Kilometers are used worldwide (except the United States and a few others) for road signage, geographic distance, athletic events, and scientific distances at planetary scale. Speed limits in most countries are given in km/h.
Adopted 1795 in France as part of the original metric system; the kilometer became the global standard for road and geographic distance through the 19th and 20th century metric adoption.
Fermi to Kilometer conversion formula
The relationship between fermis and kilometers:
To convert fermis to kilometers, multiply the value in fermis by 1e-18. To reverse, multiply kilometers by 1e+18.
How to use this converter
Type a value into the calculator. The result in kilometers updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Kilometer to Fermi converter for the reverse direction.
Step-by-step: convert fermis to kilometers
- Write down the value in fermis (F).
- Multiply that value by the factor 1e-18.
- The product is the equivalent value in kilometers (km).
- To reverse, multiply the kilometer value by 1e+18.
Worked examples
Example 1 — Convert 1 F to km:
1 × 1e-18 = 1e-18 km
Example 2 — Convert 100 F to km:
100 × 1e-18 = 1e-16 km
Real-world example — Twelve orders of magnitude
A trillion fermis maps to a single, recognizable distance in kilometers. This kind of conversion arises in cosmology and electromagnetic-spectrum exercises where atomic and astronomical scales sit side by side.
1e+12 F × 1e-18 = 1e-6 km
Real-world example — Wavelength to road distance
A trillion fermis equals one kilometer — the kind of conversion that appears in physics problems spanning the electromagnetic spectrum across many orders of magnitude.
1e+12 F × 1e-18 = 1e-6 km
Fermi to Kilometer conversion table
Standard reference values for converting fermis to kilometers:
| Fermi [F] | Kilometer [km] |
|---|---|
| 0.01 | 1e-20 |
| 0.1 | 1e-19 |
| 1 | 1e-18 |
| 2 | 2e-18 |
| 3 | 3e-18 |
| 4 | 4e-18 |
| 5 | 5e-18 |
| 10 | 1e-17 |
| 20 | 2e-17 |
| 30 | 3e-17 |
| 40 | 4e-17 |
| 50 | 5e-17 |
| 100 | 1e-16 |
| 500 | 5e-16 |
| 1000 | 1e-15 |
Frequently asked questions
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Metric / SI (4 units)
Imperial / US Customary (4 units)
Sources & references
Conversion factor (1 F = 1e-18 km) 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.