Carats to Micrograms
Type a value in either box to convert between carats and micrograms. The factor is 200000.
| Carats | Micrograms |
|---|---|
| 1 ct | 200000 µg |
| 2 ct | 400000 µg |
| 3 ct | 600000 µg |
| 5 ct | 1000000 µg |
| 10 ct | 2000000 µg |
| 25 ct | 5000000 µg |
| 50 ct | 10000000 µg |
| 100 ct | 20000000 µg |
How to use
- Enter a value in the Carats field.
- The Micrograms figure appears immediately — no button to press.
- Typing in the Micrograms field converts back to Carats the same way.
- Use the reference table for the values that come up most often.
Carats to Micrograms formula
The factor from carats to micrograms is 200000.
µg = ct × 200000
Why this factor: the carat and the microgram are both defined against the kilogram, so dividing one definition by the other gives 200000 directly. Both definitions are set out in full below.
To go the other way, divide by 200000 — or use the Micrograms to Carats converter, which is the same calculation reversed.
Worked example
Start with 2 ct. Multiply by 200000 to get 400000 µg.
2 ct × 200000 = 400000 µg
The converter above does this for any value you type, in either direction.
What is a carat?
A metric carat is the standard mass unit for gemstones.
Definition: Exactly 200 milligrams — that is, 0.2 gram — standardized internationally in 1907.
Where it is used: Diamond and gemstone weight throughout the jewellery trade.
Worth knowing: Do not confuse the carat (gemstone mass) with the karat (gold purity out of 24). A 1-carat diamond and 24-karat gold measure entirely different things.
What is a microgram?
A microgram is one millionth of a gram, used where quantities are vanishingly small but still matter.
Definition: Exactly 1×10⁻⁹ kilogram by SI prefix definition. Symbol µg.
Where it is used: Trace nutrients such as vitamin B12 and folate, hormone doses, and air-quality measurements.
Worth knowing: Sometimes abbreviated 'mcg' on labels specifically to avoid µg being misread as mg — a thousandfold dosing error.
Carats vs Micrograms
The carat is a specialized unit while the microgram is a metric unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many micrograms are in a carat?
One carat equals 200000 micrograms.
What is the formula to convert carats to micrograms?
Multiply the number of carats by 200000. To reverse it, divide by 200000 instead.
How do I convert micrograms back to carats?
Divide by 200000, which is the same as multiplying by 5e-06.
How many micrograms are in 10 carats?
10 ct works out to 2000000 µg.
Is there anything to watch out for with carats?
Do not confuse the carat (gemstone mass) with the karat (gold purity out of 24). A 1-carat diamond and 24-karat gold measure entirely different things.
How is the carat defined?
Exactly 200 milligrams — that is, 0.2 gram — standardized internationally in 1907.