A metric carat is exactly 200 milligrams.
Carats to Rontograms Converter — ct to rg
Convert Carat (ct) to Rontogram (rg) using the exact conversion factor (1 carat = 2e+26 rontogram). See the formula, worked examples, and conversion table.
Carats to Rontograms 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.
Rontogram is 1e-27 gram units.
Result = input x 0.0002 / 1e-30.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Carats to Rontograms
Weight conversions between Carat and Rontogram 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: A metric carat is exactly 200 milligrams, and rontogram is 1e-27 gram units.
Formula
rontograms = carats × 2e+26
This factor comes from each unit's defined relationship to the category's base unit: 1 carat equals 0.0002 base units, and 1 rontogram equals 1e-30 base units, so dividing one by the other gives the direct carat-to-rontogram factor of 2e+26.
Simple example
1 ct × 2e+26 = 2e+26 rg
1 carat = 2e+26 rontograms.
Real-world example
50 ct × 2e+26 = 1e+28 rg
50 carats = 1e+28 rontograms.
Conversion table
| Carat (ct) | Rontogram (rg) |
|---|---|
| 1 ct | 2e+26 rg |
| 5 ct | 1e+27 rg |
| 10 ct | 2e+27 rg |
| 25 ct | 5e+27 rg |
| 50 ct | 1e+28 rg |
| 100 ct | 2e+28 rg |
Reverse conversion: Rontogram to Carat
2e+26 rg × 5e-27 = 1 ct
2e+26 rontograms = 1 carats.
carats = rontograms × 5e-27
For a page dedicated to this direction, see Rontogram to Carat.
Understanding the Carat (ct)
A metric carat is exactly 200 milligrams.
Understanding the Rontogram (rg)
Rontogram is 1e-27 gram units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many rontograms are in 1 carat?
1 carat equals 2e+26 rontograms, using the exact defined conversion factor rather than an estimate.
How do I convert carat to rontogram?
Multiply the carat value by 2e+26. The converter above does this instantly to whatever precision you set.
How do I convert rontogram back to carat?
Use the reverse factor: 1 rontogram equals 5e-27 carats. You can also use the swap control in the converter above to flip the direction instantly.
What is a carat?
Carat (ct) is a unit of mass/weight.
What is a rontogram?
Rontogram (rg) is a unit of mass/weight.
Is the carat to rontogram conversion exact?
Yes. Both carat and rontogram are defined by fixed standards rather than physical artifacts, so the factor of 2e+26 used above is exact to as many digits as you choose to display.