Convert weight and mass units — kilograms, pounds, grams, ounces, tons, carats and more.
| Unit | Name | Value |
|---|---|---|
| 0.001 ct | 0.00308642 gr | |
| 0.01 ct | 0.0308642 gr | |
| 0.1 ct | 0.308642 gr | |
| 1 ct | 3.08642 gr | |
| 5 ct | 15.4321 gr | |
| 10 ct | 30.8642 gr | |
| 50 ct | 154.321 gr | |
| 100 ct | 308.642 gr | |
| 1000 ct | 3086.42 gr |
The Milligram (mg) and the Gram (g) are both units of weight & mass. Converting between them is straightforward using the formula above.
Formula: 1 ct = 3.08642 gr
This converter uses internationally recognized conversion factors. All calculations are performed client-side in your browser — no data is sent to any server.
| Carat (ct) | Grain (gr) | Real-world context |
|---|---|---|
| 1 ct | 3.0864198 gr | solitaire diamond |
| 5 ct | 15.4320988 gr | |
| 10 ct | 30.8641975 gr | collector gem |
| 50 ct | 154.321 gr | |
| 100 ct | 308.642 gr |
1 carat (ct) equals exactly 3.0864198 grains (gr). Use the formula: ct × 3.0864198 = gr.
To convert carats to grains, multiply your value in carats by 3.0864198. For example, 5 ct × 3.0864198 = 15.4320988 gr.
100 carats = 308.642 grains. Calculation: 100 × 3.0864198 = 308.642.
To convert grains back to carats, divide by 3.0864198 (or multiply by 0.324). Example: 10 gr ÷ 3.0864198 = 3.24 ct.
Yes. This converter uses the internationally recognised exact conversion factor: 1 ct = 3.0864198 gr. All calculations are performed in your browser with no rounding until display.
10 carats = 30.8641975 grains. Simply multiply by 3.0864198.
Converting carats to grains is commonly needed for jewellery valuation, gemstone trading, precious metal buying and selling, and hallmarking compliance where one system uses ct and another uses gr.
The metric carat (ct) is the unit of mass used worldwide for gemstones and pearls, equal to exactly 200 milligrams (0.2 g). It is distinct from "karat" (K), the measure of gold purity (24K = 100% gold). A 1-carat diamond weighs exactly 0.2 g; the famous 45.52-carat Hope Diamond weighs approximately 9.1 g.
The grain (gr) is the smallest unit in the avoirdupois, troy, and apothecary weight systems, equal to exactly 64.79891 milligrams (0.06479891 g). All three systems share the same grain as base: one avoirdupois pound = 7,000 grains; one troy pound = 5,760 grains. The grain is still used in ballistics (bullet and powder weights) and some pharmaceutical contexts.
The word "carat" derives from Greek keration (κεράτιον), meaning carob pod. Carob seeds were believed to have remarkably uniform weight and were used as counterweights for balancing precious stones. The carat value varied across countries (0.187–0.216 g) until the Fourth General Conference on Weights and Measures standardised the metric carat at exactly 200 mg in 1907. Most countries adopted the metric carat between 1914 and 1930.
Interesting fact: The largest gem-quality diamond ever found, the Cullinan Diamond (1905), weighed 3,106.75 carats (621.35 g) before being cut into 9 major and 96 minor stones, two of which are in the British Crown Jewels.
The grain is among the oldest measurement units in history, derived from the average weight of a grain of barleycorn (or wheat) — a practical standard used in ancient Egypt, Greece, and Rome. England formalised the barleycorn grain in the 15th century as the foundation of its weight system. The British Weights and Measures Act 1824 defined the grain, and the value remains unchanged today.
Interesting fact: The original grain was calibrated by laying dried barleycorns end-to-end — 32 grains equalled one inch in 13th-century England. Today, 9mm pistol bullets typically weigh 115–147 grains (7.5–9.5 g), and gunpowder charges are specified in grains for reloading.