Attogram is 1e-18 gram units.
Attograms to Femtograms Converter — ag to fg
Convert Attogram (ag) to Femtogram (fg) using the exact conversion factor (1 attogram = 0.001 femtogram). See the formula, worked examples, conversion table, history, and common uses.
Attograms to Femtograms converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
Context values
Some unit families need one extra value for a physically accurate result.
Femtogram is 1e-15 gram units.
Result = input x 1e-21 / 1e-18.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Attograms to Femtograms
Weight conversions between Attogram and Femtogram come up constantly in everyday commerce, shipping, and cooking, since US packaging is usually labeled in pounds while most of the rest of the world uses kilograms. Attogram is most often used for nanotechnology and single-molecule mass measurement.
Formula
femtograms = attograms × 0.001
This factor comes from each unit's defined relationship to the category's base unit: 1 attogram equals 1e-21 base units, and 1 femtogram equals 1e-18 base units, so dividing one by the other gives the direct attogram-to-femtogram factor of 0.001.
Simple example
1 ag × 0.001 = 0.001 fg
1 attogram = 0.001 femtograms.
Real-world example
50 ag × 0.001 = 0.05 fg
50 attograms = 0.05 femtograms.
Conversion table
| Attogram (ag) | Femtogram (fg) |
|---|---|
| 1 ag | 0.001 fg |
| 5 ag | 0.005 fg |
| 10 ag | 0.01 fg |
| 25 ag | 0.025 fg |
| 50 ag | 0.05 fg |
| 100 ag | 0.1 fg |
Reverse conversion: Femtogram to Attogram
0.001 fg × 1000 = 1 ag
0.001 femtograms = 1 attogram.
attograms = femtograms × 1000
For a page dedicated to this direction, see Femtogram to Attogram.
Understanding the Attogram
Attogram (ag) measures mass. An attogram is 10⁻¹⁸ grams (10⁻²¹ kilograms) — 'atto-' is the SI prefix for one quintillionth. It is classified as a SI derived (metric prefix) unit.
Where it's used: Used in specialized scientific measurement, not everyday contexts
Uses of the Attogram today
- Nanotechnology and single-molecule mass measurement
- Analytical chemistry at extremely small mass scales
- Comparing against atomic-scale mass units like the atomic mass unit
History of the Attogram
The attogram is simply the gram combined with the SI prefix 'atto-' (10⁻¹⁸), one of the small-scale metric prefixes introduced by the International Committee for Weights and Measures as part of the broader SI prefix system, not a unit with its own separate history.
Historical origin. Attogram was not the invention of a single named person; it developed through the process described above.
Understanding the Femtogram (fg)
Femtogram is 1e-15 gram units.
Attogram — sources
- BIPM SI Brochure — SI prefixes — Defines 'atto-' as the prefix for 10⁻¹⁸.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many femtograms are in 1 attogram?
1 attogram equals 0.001 femtograms, using the exact defined conversion factor rather than an estimate.
How do I convert attogram to femtogram?
Multiply the attogram value by 0.001. The converter above does this instantly to whatever precision you set.
How do I convert femtogram back to attogram?
Use the reverse factor: 1 femtogram equals 1,000 attograms. You can also use the swap control in the converter above to flip the direction instantly.
What is a attogram?
Attogram (ag) measures mass. An attogram is 10⁻¹⁸ grams (10⁻²¹ kilograms) — 'atto-' is the SI prefix for one quintillionth. It is classified as a SI derived (metric prefix) unit.
What is a femtogram?
Femtogram (fg) is a unit of mass/weight.
Is the attogram to femtogram conversion exact?
Yes. Both attogram and femtogram are defined by fixed standards rather than physical artifacts, so the factor of 0.001 used above is exact to as many digits as you choose to display.
Where is the attogram still used today?
Used in specialized scientific measurement, not everyday contexts