Convert Femtometer to Micrometer
Convert femtometers to micrometers instantly. 1 femtometer = 1e-9 micrometer — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Micrometer to Femtometer converter for the reverse conversion.
Units explained
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 The name fermi (after Enrico Fermi) was used informally from the 1950s but officially superseded by femtometer.
Micrometer
A micrometer (also called a micron) is a metric unit of length equal to one millionth of a meter (1×10⁻⁶ m). It is the standard unit for measuring microscopic dimensions in biology, materials science, and semiconductor manufacturing.
Defined alongside the meter when France adopted the metric system in 1795, using the SI prefix micro- (from Greek mikros, "small") to denote one-millionth.
Micrometers are used to measure cell sizes, bacteria, semiconductor process nodes, fiber diameters, dust particles, and wavelengths of infrared radiation. The diameter of a human hair is about 70 μm.
Defined in 1795 as part of the original French metric system; the name "micron" was officially deprecated by the BIPM in 1967 in favor of micrometer.
Femtometer to Micrometer conversion formula
The relationship between femtometers and micrometers:
To convert femtometers to micrometers, multiply the value in femtometers by 1e-9. To reverse, multiply micrometers by 1e+9.
How to use this converter
Type a value into the calculator. The result in micrometers updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Micrometer to Femtometer converter for the reverse direction.
Step-by-step: convert femtometers to micrometers
- Write down the value in femtometers (fm).
- Multiply that value by the factor 1e-9.
- The product is the equivalent value in micrometers (μm).
- To reverse, multiply the micrometer value by 1e+9.
Worked examples
Example 1 — Convert 1 fm to μm:
1 × 1e-9 = 1e-9 μm
Example 2 — Convert 100 fm to μm:
100 × 1e-9 = 1e-7 μm
Real-world example — Sub-visible-light wavelength
500 femtometers (the green-yellow visible band) equals 0.5 micrometers — the canonical conversion in optics between wavelength specifications and micron-scale lens-coating thicknesses.
500 fm × 1e-9 = 5e-7 μm
Real-world example — Spanning sub-micron to micron scale
Crossing from femtometers to micrometers is the everyday workflow of microscopy and semiconductor engineering — a measurement of 1000 femtometers translates to a much more compact value in micrometers that fits the scale of biological cells and process nodes.
1000 fm × 1e-9 = 1e-6 μm
Femtometer to Micrometer conversion table
Standard reference values for converting femtometers to micrometers:
| Femtometer [fm] | Micrometer [μm] |
|---|---|
| 0.01 | 1e-11 |
| 0.1 | 1e-10 |
| 1 | 1e-9 |
| 2 | 2e-9 |
| 3 | 3e-9 |
| 4 | 4e-9 |
| 5 | 5e-9 |
| 10 | 1e-8 |
| 20 | 2e-8 |
| 30 | 3e-8 |
| 40 | 4e-8 |
| 50 | 5e-8 |
| 100 | 1e-7 |
| 500 | 5e-7 |
| 1000 | 1e-6 |
Frequently asked questions
How many micrometers is 1 femtometer?
How do I convert femtometers to micrometers?
How do I convert micrometers back to femtometers?
How many micrometers is 100 femtometers?
Popular length unit conversions
Convert Femtometer to other length units
Show all Femtometer conversions
Metric / SI (17 units)
Imperial / US Customary (4 units)
Sources & references
Conversion factor (1 fm = 1e-9 μm) 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.