Femtometer is 1e-15 meter units.
Femtometers to Astronomical units Converter — fm to AU
Convert Femtometer (fm) to Astronomical unit (AU) using the exact conversion factor (1 femtometer = 6.684587e-27 astronomical unit). See the formula, worked examples, conversion table, history, and common uses.
Femtometers to Astronomical units converter
Converter
Length Converter
Convert SI, imperial, US customary, astronomical, scientific, and historical length units.
Context values
Some unit families need one extra value for a physically accurate result.
An astronomical unit is the mean Earth-Sun distance.
Result = input x 1e-15 / 1.49597871e+11.
Length uses the meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Femtometers to Astronomical units
Femtometer and Astronomical unit both measure length. Specifically: Femtometer is 1e-15 meter units, and an astronomical unit is the mean Earth-Sun distance.
Formula
astronomical units = femtometers × 6.684587e-27
This factor comes from each unit's defined relationship to the category's base unit: 1 femtometer equals 1e-15 base units, and 1 astronomical unit equals 149597870700 base units, so dividing one by the other gives the direct femtometer-to-astronomical unit factor of 6.684587e-27.
Simple example
1 fm × 6.684587e-27 = 6.684587e-27 AU
1 femtometer = 6.684587e-27 astronomical units.
Real-world example
10 fm × 6.684587e-27 = 6.684587e-26 AU
10 femtometers = 6.684587e-26 astronomical units.
Conversion table
| Femtometer (fm) | Astronomical unit (AU) |
|---|---|
| 1 fm | 6.684587e-27 AU |
| 5 fm | 3.342294e-26 AU |
| 10 fm | 6.684587e-26 AU |
| 21.0975 fm | 1.410281e-25 AU |
| 42.195 fm | 2.820562e-25 AU |
| 100 fm | 6.684587e-25 AU |
Reverse conversion: Astronomical unit to Femtometer
6.684587e-27 AU × 1.495979e+26 = 0.9999999817 fm
6.684587e-27 astronomical units = 0.9999999817 femtometers.
femtometers = astronomical units × 1.495979e+26
For a page dedicated to this direction, see Astronomical unit to Femtometer.
Understanding the Femtometer (fm)
Femtometer is 1e-15 meter units.
Understanding the Astronomical unit
Astronomical unit (AU) measures distance. The astronomical unit is defined as exactly 149,597,870,700 meters, close to the average Earth-Sun distance. It is classified as a Non-SI unit accepted for use with SI (astronomical).
Where it's used: Used internationally in astronomy for solar-system-scale distances.
Uses of the Astronomical unit today
- Measuring distances within the solar system (planetary orbits)
- Astronomical calculations and spacecraft navigation
- Popular science communication about the solar system
History of the Astronomical unit
The astronomical unit originated from 17th-19th century attempts to measure the Earth-Sun distance, refined over time using transits of Venus and later radar and spacecraft ranging.
In 2012, the International Astronomical Union fixed the AU at exactly 149,597,870,700 meters, replacing its earlier definition (tied to gravitational calculations) with a simple fixed distance, independent of the slightly-variable actual Earth-Sun distance.
Historical origin. Astronomical unit was not the invention of a single named person; it developed through the process described above.
Astronomical unit — sources
- IAU Resolution B2 (2012) — Fixes the astronomical unit at exactly 149,597,870,700 meters.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many astronomical units are in 1 femtometer?
1 femtometer equals 6.684587e-27 astronomical units, using the exact defined conversion factor rather than an estimate.
How do I convert femtometer to astronomical unit?
Multiply the femtometer value by 6.684587e-27. The converter above does this instantly to whatever precision you set.
How do I convert astronomical unit back to femtometer?
Use the reverse factor: 1 astronomical unit equals 1.495979e+26 femtometers. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtometer?
Femtometer (fm) is a unit of length.
What is a astronomical unit?
Astronomical unit (AU) measures distance. The astronomical unit is defined as exactly 149,597,870,700 meters, close to the average Earth-Sun distance. It is classified as a Non-SI unit accepted for use with SI (astronomical).
Is the femtometer to astronomical unit conversion exact?
Yes. The astronomical unit is defined as exactly 149,597,870,700 meters, close to the average Earth-Sun distance. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.