US Fluid Drams (fl-dr) to Glas (glas) conversion

What is the US Fluid Dram?

The US fluid dram (also spelled fluid drachm) is a small United States customary unit of liquid volume, historically important in pharmacy and medicine for dispensing doses of liquid medication.

Definition

The US fluid dram is defined as one eighth of a US fluid ounce, or equivalently 60 minims.

$$1\ \text{fl-dr} = 0.00369669\ \text{L}$$

Since the US fluid ounce — which the NIST Guide to the SI lists at exactly 2.957353×10⁻⁵ m³ — is exactly 29.5735295625 mL, a fluid dram equals 3.6966912 mL. The UK/imperial fluid drachm is slightly larger at about 3.5516 mL (1/8 of the imperial fluid ounce).

Origin and History

"Dram" derives from the Greek drachma, an ancient coin and weight. The apothecaries' system split the fluid ounce into 8 fluid drams and each dram into 60 minims, giving pharmacists a fine graduation for compounding and measuring liquid remedies.

Law and Notable Facts

The fluid dram is a legal US customary unit but is now largely obsolete in clinical practice, superseded by milliliters. Its legacy survives in the term "dram" for a small pour of whisky and in the traditional 8-dram, 1-fluid-ounce medicine bottle.

Real-World Examples and Conversions

• A single US fluid dram is about 3.70 mL, roughly three-quarters of a metric teaspoon.
• 8 US fluid drams equal 1 US fluid ounce (29.5735 mL).
• 1 US fluid dram = 60 minims ≈ 0.75 teaspoon; 1 mL ≈ 0.2705 US fluid dram.

What is Glas?

Glas is a Swedish unit of volume used in cooking and baking. The word "glas" is Swedish for "glass," reflecting its origin as a measure based on the contents of a drinking glass. In modern Swedish recipes it is a standardized measure.

Definition of Glas

In the standardized Swedish system of kitchen measures (matmått), one glas is defined as 2 deciliters, which is equal to 200 millilitres.

$$1 \text{ glas} = 2 \text{ dL} = 200 \text{ mL} = 0.2 \text{ L}$$

Like the other Swedish cooking measures (kryddmått, tesked, matsked, and kaffekopp), the glas follows the metric system, so conversions to litres and millilitres are exact.

Relationship to Other Units

The glas fits neatly into the family of Swedish volume measures and the wider metric system:

• 1 glas = 200 mL = 20 centilitres
• 1 glas = 2 deciliter (dL)
• 1 glas ≈ 6.76 US fluid ounces
• 1 glas ≈ 7.04 Imperial fluid ounces
• 1 glas ≈ 0.85 US cups

Because 1 kaffekopp (coffee cup) is 1.5 dL, a glas (2 dL) is slightly larger than a kaffekopp.

Historical Context

The glas belongs to the set of household measures that Swedish cooks have long used in place of scales. As Sweden adopted the metric system in the late 19th century, these traditional kitchen measures were standardized to round metric values, giving the glas its modern value of 2 dL. There is no single law or historical figure directly associated with it; rather, it reflects the gradual standardization of everyday cooking measurements.

Real-World Examples

Glas measurements appear frequently in Swedish and Scandinavian recipes:

• Baking: A cake recipe might call for 3 glas of flour.
• Cooking: A sauce or soup might need 1 glas of cream or stock.
• Drinks: Punch and cordial recipes are often measured in glas.

Converting Glas

Because the glas is defined in exact metric terms, conversion is straightforward. To convert a volume in glas to litres:

$$\text{Volume in Liters} = \text{Volume in Glas} \times 0.2$$

For example, 4 glas equals $4 \times 0.2 = 0.8$ litres (800 mL).