Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
Carats to Milligrams Converter (ct to mg)
Carats
ct → mg
200 mg
1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
- You typed
- 1 ct
- One mg is
- 0 ct
- How it’s calculated
- milligrams = carats × 200. Exact metric carat.
Carats to Milligrams conversion table
Common ct values in mg. Same factor as the converter above: milligrams = carats × 200. Exact metric carat.
| Carats | Milligrams |
|---|---|
| 0.3 ct | 50 mg |
| 0.5 ct | 100 mg |
| 1 ct | 200 mg |
| 2 ct | 400 mg |
| 5 ct | 1,000 mg |
| 10 ct | 2,000 mg |
| 20 ct | 4,000 mg |
| 25 ct | 5,000 mg |
| 50 ct | 10,000 mg |
| 100 ct | 20,000 mg |
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Carats
The “Carats” value used in this tool’s formula. Adjust it to see results update live.
milligrams = carats × 200. Exact metric carat.
The metric carat is exactly 200 mg (0.2 g) since 1907. A 1 ct diamond is 200 mg. Jewelers still cut “points” (0.01 ct = 2 mg). This is not a gold-karat purity scale.
How this calculator works
The metric carat is exactly 200 mg (0.2 g) since 1907. A 1 ct diamond is 200 mg. Jewelers still cut “points” (0.01 ct = 2 mg). This is not a gold-karat purity scale. milligrams = carats × 200. Exact metric carat. Scenario: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
milligrams = carats × 200. Exact metric carat.
Scenario: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
When to use this Carats to Milligrams
Common use cases
- The metric carat is exactly 200 mg (0.2 g) since 1907. A 1 ct diamond is 200 mg. Jewelers still cut “points” (0.01 ct = 2 mg). This is not a gold-karat purity scale.
- Sanity-check with this scenario: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
- The relationship is: milligrams = carats × 200. Exact metric carat.
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: Carats
- milligrams = carats × 200. Exact metric carat.
- Scenario on the page: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
How to Convert Carats to Milligrams
- 1Enter Carats. Use the values you have, not a catalog average, unless that is all you know.
- 2milligrams = carats × 200. Exact metric carat.
- 3Scenario: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
milligrams = carats × 200. Exact metric carat.
1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
Variable definitions
- value
Carats
The “Carats” field. Default 1; typical range 0–1000000000.
- The conversion (milligrams = carats × 200. Exact metric carat.) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Karat (k) is gold purity. Carat (ct) is gem mass. Different words on purpose.
Related calculators
Unit Converters
- SI Gram Prefix ConverterMass prefixes attach to the gram, not the kilogram. Kilogram is already kilo + gram. Scale yottagram down to yoctogram, or milligram to microgram, without mixing in pounds. Jewelry carats and troy ounces are separate legal pages.
- Carats to GramsA metric carat is 0.2 g, defined in 1907 so jewelers would stop arguing. A 1 ct diamond is 0.2 g — the size you see is cut, not this mass. Gold “karat” (purity) is a different word on purpose.
- Grains to MilligramsAmmunition, arrows, and old pharmacy weights still use grains. One grain is 64.79891 mg. A “115 gr” 9 mm bullet is 7.45 g. This is not a grain of rice.
- Milligrams to GramsPills, caffeine, and lab reagents print milligrams. Recipes print grams. Divide mg by 1,000. A 500 mg tablet is 0.5 g — not 500 g. That mix-up is how people scare themselves with supplement labels.
- Acres to HectaresUS farm ads in acres, EU paperwork in hectares. Divide acres by 2.471. Ten acres is 4.05 ha. A 160-acre quarter-section is 64.7 ha.
- Acres to Square FeetUS land: one acre is 43,560 ft², a chain-and-furlong leftover that refused to die. A quarter-acre lot is 10,890 ft². Multiply acres by 43,560. Soccer-field metaphors are not a survey.
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Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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