Convert Exameter to Femtometer
Convert exameters to femtometers instantly. 1 exameter = 1e+33 femtometer — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Femtometer to Exameter converter for the reverse conversion.
Units explained
Exameter
An exameter is a metric unit of length equal to one quintillion meters (1×10¹⁸ m). It is among the largest defined SI prefix units of length and appears almost exclusively in astrophysical contexts.
The exameter uses the SI prefix exa- (from Greek hex, six, related to the exponent's powers-of-thousand grouping), adopted by the CGPM in 1975 to denote 10¹⁸.
Exameters could be used to express galactic-scale distances. One kiloparsec is approximately 30.9 Em. Astronomy generally uses parsecs, kiloparsecs, and megaparsecs instead.
SI prefix exa- adopted in 1975; the exameter has very limited practical use because galactic-scale astronomy has its own well-established unit system.
Femtometer
A femtometer is a metric unit of length equal to one quadrillionth of a meter (1×10⁻¹⁵ m). It is the standard unit for measuring sub-atomic dimensions, particularly the size of atomic nuclei. The femtometer is also known historically as the fermi.
The femtometer was defined using the SI prefix femto- (from Danish femten, meaning fifteen), adopted by the CGPM in 1964 to denote one quadrillionth. The synonymous name fermi was named after Italian physicist Enrico Fermi.
Femtometers are used to express the size of atomic nuclei (typically 1–10 fm in diameter), the range of strong nuclear forces, and characteristic dimensions in particle physics. The proton charge radius is approximately 0.84 fm.
SI prefix femto- adopted in 1964; the unit became standard in nuclear physics through the late 20th century. The name fermi (after Enrico Fermi) was used informally from the 1950s but officially superseded by femtometer.
Exameter to Femtometer conversion formula
The relationship between exameters and femtometers:
To convert exameters to femtometers, multiply the value in exameters by 1e+33. To reverse, multiply femtometers by 1e-33.
How to use this converter
Type a value into the calculator. The result in femtometers updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Femtometer to Exameter converter for the reverse direction.
Step-by-step: convert exameters to femtometers
- Write down the value in exameters (Em).
- Multiply that value by the factor 1e+33.
- The product is the equivalent value in femtometers (fm).
- To reverse, multiply the femtometer value by 1e-33.
Worked examples
Example 1 — Convert 1 Em to fm:
1 × 1e+33 = 1e+33 fm
Example 2 — Convert 100 Em to fm:
100 × 1e+33 = 1e+35 fm
Exameter to Femtometer conversion table
Standard reference values for converting exameters to femtometers:
| Exameter [Em] | Femtometer [fm] |
|---|---|
| 0.01 | 1e+31 |
| 0.1 | 1e+32 |
| 1 | 1e+33 |
| 2 | 2e+33 |
| 3 | 3e+33 |
| 4 | 4e+33 |
| 5 | 5e+33 |
| 10 | 1e+34 |
| 20 | 2e+34 |
| 30 | 3e+34 |
| 40 | 4e+34 |
| 50 | 5e+34 |
| 100 | 1e+35 |
| 500 | 5e+35 |
| 1000 | 1e+36 |
Frequently asked questions
How many femtometers is 1 exameter?
How do I convert exameters to femtometers?
How do I convert femtometers back to exameters?
How many femtometers is 100 exameters?
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Sources & references
Conversion factor (1 Em = 1e+33 fm) 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.