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Convert Carat to Grain (ct to gr) instantly with accurate, readable results.
Use our Mass Unit Converter to convert between grams, kilograms, pounds, ounces, and other weight units instantly. Designed for cooking, science, fitness, and engineering needs, this unit conversion tool offers accurate results between metric and imperial systems. Whether you’re tracking body weight, measuring ingredients, or handling heavy machinery, our mass unit conversion calculator has you covered.
Carat (ct) — a metric unit of mass for gemstones
It is defined as exactly 200 milligrams, or one fifth of a gram. Used worldwide for measuring diamonds, gemstones, pearls, and other jewels; it should not be confused with karat, which measures gold purity.
- Symbol: ct
- System: Non-SI metric unit for mass; used with SI
- Exact relations: 1 ct = 200 mg = 0.2 g = 0.0002 kg
- Imperial equivalents (derived from 1 lb = 0.45359237 kg exactly): 1 ct ≈ 0.00705479 oz ≈ 0.000440925 lb
- Typical examples: a small diamond ~0.25 ct; an engagement-ring diamond ~1 ct; large gemstones may be several ct.
Grain (gr) — a small imperial and US customary unit of mass
It is defined as exactly 1/7000 of an avoirdupois pound; since 1 lb = 0.45359237 kg exactly, 1 gr = 64.79891 mg exactly. Used mainly for measuring bullets, gunpowder, arrows, and some pharmaceutical or historical masses.
- Symbol: gr
- System: Imperial and US customary unit for mass
- Exact relations: 1 gr = 1/7000 lb = 1/437.5 oz = 64.79891 mg
- Metric equivalents: 1 gr = 0.06479891 g ≈ 0.0000647989 kg
- Typical examples: a small bullet ~40 gr; a larger rifle bullet ~150 gr; an aspirin tablet was historically 5 gr.