Attogram is 1e-18 gram units.
Attograms to Carats Converter — ag to ct
Convert Attogram (ag) to Carat (ct) using the exact conversion factor (1 attogram = 5e-18 carat). See the formula, worked examples, conversion table, history, and common uses.
Attograms to Carats 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.
A metric carat is exactly 200 milligrams.
Result = input x 1e-21 / 0.0002.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Attograms to Carats
Weight conversions between Attogram and Carat 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
carats = attograms × 5e-18
This factor comes from each unit's defined relationship to the category's base unit: 1 attogram equals 1e-21 base units, and 1 carat equals 0.0002 base units, so dividing one by the other gives the direct attogram-to-carat factor of 5e-18.
Simple example
1 ag × 5e-18 = 5e-18 ct
1 attogram = 5e-18 carats.
Real-world example
50 ag × 5e-18 = 2.5e-16 ct
50 attograms = 2.5e-16 carats.
Conversion table
| Attogram (ag) | Carat (ct) |
|---|---|
| 1 ag | 5e-18 ct |
| 5 ag | 2.5e-17 ct |
| 10 ag | 5e-17 ct |
| 25 ag | 1.25e-16 ct |
| 50 ag | 2.5e-16 ct |
| 100 ag | 5e-16 ct |
Reverse conversion: Carat to Attogram
5e-18 ct × 2e+17 = 1 ag
5e-18 carats = 1 attogram.
attograms = carats × 2e+17
For a page dedicated to this direction, see Carat 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 Carat (ct)
A metric carat is exactly 200 milligrams.
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 carats are in 1 attogram?
1 attogram equals 5e-18 carats, using the exact defined conversion factor rather than an estimate.
How do I convert attogram to carat?
Multiply the attogram value by 5e-18. The converter above does this instantly to whatever precision you set.
How do I convert carat back to attogram?
Use the reverse factor: 1 carat equals 2e+17 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 carat?
Carat (ct) is a unit of mass/weight.
Is the attogram to carat conversion exact?
Yes. Both attogram and carat are defined by fixed standards rather than physical artifacts, so the factor of 5e-18 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