Convert Carat (metric) to Grain
Convert carats (metric) to grains instantly. 1 carat (metric) = 3.0864721469 grain — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Grain to Carat (metric) converter for the reverse conversion.
Units explained
Carat (metric)
The metric carat (ct) equals exactly 200 milligrams (0.0002 kg).
From Arabic 'qirat' and Greek 'keration', the carob seed once used as a counterweight.
The worldwide standard for gemstone and diamond mass.
The metric carat was fixed at 200 mg internationally in 1907.
Grain
The grain (gr) equals 1/7000 of an avoirdupois pound, about 64.8 milligrams.
Based on the nominal mass of a single barley grain.
Ammunition and bullet mass, archery, and historical pharmacy.
Standardized through the English avoirdupois system and retained in 1959.
Carat (metric) to Grain conversion formula
The relationship between carats (metric) and grains:
To convert carats (metric) to grains, multiply the value in carats (metric) by 3.0864721469. To reverse, multiply grains by 0.3239945.
How to use this converter
Type a value into the calculator. The result in grains updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Grain to Carat (metric) converter for the reverse direction.
Step-by-step: convert carats (metric) to grains
- Write down the value in carats (metric) (ct).
- Multiply that value by the factor 3.0864721469.
- The product is the equivalent value in grains (gr).
- To reverse, multiply the grain value by 0.3239945.
Worked examples
Example 1 — Convert 1 ct to gr:
1 × 3.0864721469 = 3.0864721469 gr
Example 2 — Convert 100 ct to gr:
100 × 3.0864721469 = 308.6472146904 gr
Real-world example — Plastic-film thickness alternates
A 150-carat (metric) plastic film converts cleanly to grains — useful for packaging buyers reconciling supplier datasheets across metric and US measurement systems.
150 ct × 3.0864721469 = 462.9708220356 gr
Real-world example — Hair-width scale measurements
A 70-carat (metric) measurement (about the diameter of a human hair) is the kind of value materials engineers regularly express in adjacent micro-scale units like grains for direct comparison across supplier datasheets.
70 ct × 3.0864721469 = 216.0530502833 gr
Real-world example — Paper and film thicknesses
At the thickness of office paper (roughly 3 carats (metric)), converting between sub-millimeter units is routine for packaging and printing buyers comparing quotes from metric and US suppliers.
3 ct × 3.0864721469 = 9.2594164407 gr
Carat (metric) to Grain conversion table
Standard reference values for converting carats (metric) to grains:
| Carat (metric) [ct] | Grain [gr] |
|---|---|
| 0.01 | 0.0308647215 |
| 0.1 | 0.3086472147 |
| 1 | 3.0864721469 |
| 2 | 6.1729442938 |
| 3 | 9.2594164407 |
| 4 | 12.3458885876 |
| 5 | 15.4323607345 |
| 10 | 30.864721469 |
| 20 | 61.7294429381 |
| 30 | 92.5941644071 |
| 40 | 123.4588858761 |
| 50 | 154.3236073452 |
| 100 | 308.6472146904 |
| 500 | 1543.2360734519 |
| 1000 | 3086.4721469037 |
Frequently asked questions
How many grains is 1 carat (metric)?
How do I convert carats (metric) to grains?
How do I convert grains back to carats (metric)?
How many grains is 100 carats (metric)?
Popular weight unit conversions
Convert Carat (metric) to other weight units
Show all Carat (metric) conversions
Metric / SI (18 units)
Avoirdupois (15 units)
Troy & Apothecary (9 units)
Indian / South Asian (6 units)
Scientific / Atomic (9 units)
Astronomical (4 units)
Biblical / Ancient (14 units)
Sources & references
Conversion factor (1 ct = 3.0864721469 gr) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.