Femtogram is 1e-15 gram units.
Femtograms to Attograms Converter — fg to ag
Convert Femtogram (fg) to Attogram (ag) using the exact conversion factor (1 femtogram = 1,000 attogram). See the formula, worked examples, conversion table, history, and common uses.
Femtograms to Attograms 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.
Attogram is 1e-18 gram units.
Result = input x 1e-18 / 1e-21.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Femtograms to Attograms
Weight conversions between Femtogram and Attogram 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. Specifically: Femtogram is 1e-15 gram units, and attogram is 1e-18 gram units.
Formula
attograms = femtograms × 1000
This factor comes from each unit's defined relationship to the category's base unit: 1 femtogram equals 1e-18 base units, and 1 attogram equals 1e-21 base units, so dividing one by the other gives the direct femtogram-to-attogram factor of 1000.
Simple example
1 fg × 1000 = 1,000 ag
1 femtogram = 1,000 attograms.
Real-world example
50 fg × 1000 = 50,000 ag
50 femtograms = 50,000 attograms.
Conversion table
| Femtogram (fg) | Attogram (ag) |
|---|---|
| 1 fg | 1,000 ag |
| 5 fg | 5,000 ag |
| 10 fg | 10,000 ag |
| 25 fg | 25,000 ag |
| 50 fg | 50,000 ag |
| 100 fg | 100,000 ag |
Reverse conversion: Attogram to Femtogram
1 ag × 0.001 = 0.001 fg
1 attogram = 0.001 femtograms.
femtograms = attograms × 0.001
For a page dedicated to this direction, see Attogram to Femtogram.
Understanding the Femtogram (fg)
Femtogram is 1e-15 gram units.
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.
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 attograms are in 1 femtogram?
1 femtogram equals 1,000 attograms, using the exact defined conversion factor rather than an estimate.
How do I convert femtogram to attogram?
Multiply the femtogram value by 1000. The converter above does this instantly to whatever precision you set.
How do I convert attogram back to femtogram?
Use the reverse factor: 1 attogram equals 0.001 femtograms. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtogram?
Femtogram (fg) is a unit of mass/weight.
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.
Is the femtogram to attogram conversion exact?
Yes. Both femtogram and attogram are defined by fixed standards rather than physical artifacts, so the factor of 1000 used above is exact to as many digits as you choose to display.