Scruples to Grains (s ap to gr) Converter
1 Scruple equals 20 Grains (1 s ap = 20 gr). Convert Scruples to Grains with formula, table, and examples.
One scruple equals exactly 20 grains. This is a defining relationship within the apothecary weight system, as clean and fundamental as 24 grains per pennyweight in the troy system. The scruple was designed to contain precisely 20 grains, making subdivision into halves, quarters, fifths, and tenths straightforward for pharmaceutical compounding.
How to Convert Scruples to Grains
- Take your value in Scruples
- Multiply by 20
- Read the result in Grains
Good to Know About Scruples to Grains Conversion
The 20-grain scruple, like the 24-grain pennyweight, reflects medieval measurement design philosophy: choose numbers that divide cleanly into many fractions. Pharmacists needed halves, quarters, fifths, and tenths of a scruple more often than thirds or sixths, making 20 the ideal base. This practical numerology shaped pharmaceutical dosing for over 500 years, until the milligram rendered these divisions unnecessary.
Scruples to Grains: What You Need to Know
When 18th-century physicians wrote prescriptions in scruples and pharmacists filled them using grain weights on balance scales, the 20-grain scruple was the essential bridge between prescription notation and physical measurement. A prescription for 'half a scruple' meant exactly 10 grains, and a 'quarter scruple' meant 5 grains, both whole numbers that pharmacists could weigh precisely.
What is a Scruple? s ap
An apothecary scruple equals 20 grains or 1/3 of a dram apothecary (1.2959782 grams). A historical pharmaceutical unit largely replaced by metric measurements.
Learn more about Scruple →What is a Grain? gr
A grain is a unit of mass equal to exactly 64.79891 milligrams. It is the same in the avoirdupois, troy, and apothecaries' systems, derived from the 1959 international agreement defining the pound as exactly 0.45359237 kilograms.
Learn more about Grain →Going the other way? Use our Grains to Scruples converter.
Scruples to Grains FAQ
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Twenty was chosen because it divides evenly into halves (10), quarters (5), fifths (4), and tenths (2), all useful fractions for pharmaceutical dosing. This divisibility made the scruple practical for pharmacists who subdivided doses using balance scales and grain weights.
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Yes, the grain is identical across the apothecary, troy, and avoirdupois systems at exactly 64.79891 milligrams. The grain is the one universal unit shared by all three English weight traditions.
Non-Frequently Asked Questions About Scruples to Grains
Questions nobody should ask - but someone did.
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In the apothecary sense, zero scruples equals zero grains, which is mathematically true and pharmaceutically useless. In the moral sense, having no scruples leaves you with an undetermined number of grains, since ethical weight and physical weight unfortunately do not correlate. Many unscrupulous individuals are quite heavy.
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Both are excellent choices for pre-calculator arithmetic. Twenty divides by 2, 4, 5, and 10; twenty-four divides by 2, 3, 4, 6, 8, and 12. The pennyweight has more factors, but the scruple has rounder ones. Pharmacists preferred 20 because dose fractions in fifths and tenths were common in their work; goldsmiths preferred 24 because thirds and sixths mattered in metal alloying.
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You would get an approximation, not an exact scruple. The grain weight unit (64.8 mg) was standardized long ago against a physical reference, not against actual seeds. Modern barley grains vary from about 50 to 80 mg each, so 20 grains of barley would give you roughly 1 to 1.6 grams versus the scruple's precise 1.296 grams. Close, but not pharmacy-grade precision.
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Need the reverse? Use our Grains to Scruples converter. See all Weight & Mass converters.