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)
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.
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.
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.
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. Example: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
milligrams = carats × 200. Exact metric carat.
Example: 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 case: 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.
- Example on the page: 1 ct = 200 mg. 0.25 ct = 50 mg. 2 ct = 400 mg.
How to Convert Carats to Milligrams Step-by-Step
- 1Enter Carats. Use the values you have, not a catalog average, unless that is all you know.
- 2milligrams = carats × 200. Exact metric carat.
- 3Worked case: 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.
Example: set Carats = 1, then read the result.
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
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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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