Drop (unit)
Encyclopedia
The drop is a unit of measure
of volume
, the amount dispensed as one drop from a dropper
. It is often used in giving quantities of liquid drug
s to patients, and occasionally in cooking.
The volume of a drop is not well-defined: it depends on the device and technique used to produce the drop and on the physical properties of the fluid.
A water drop is a basic measurment. Create a dripping faucet or hose. Each drop must be a single unit; it cannot be a stream or have multiple drops coming together. Collect and count each drop using a small container calibrated in mL or ounces (1000 mL = 1 Liter and 29.6 mL = 1 fluid oz). The experiment shows that 5 drops of water equals 1 mL or about 150 drops equals 1-oz (US Fluid). A standard unit conversion gives (5.0 drops-water/1.0 mL-water) or (0.2 mL-water/1 drop-water).
There are several exact definitions of a "drop":
According to Webster dictionary, "drop" indicates the smallest volume of a liquid that may be measured. Drop size varies according to gravity, the density and the surface tension of the liquid.
In the past, a drop was another name for a minim. This meaning was used in Pharmacy
to describe a volume equal to one 60th of a fluid dram or one 480th of a fluid ounce
. This is equal to about 61.6 μL (U.S.) or 59.2 μL (Britain). Pharmacists have since moved to metric measurements, with a drop being rounded to exactly 0.05 mL (that is, 20 drops per milliliter). In hospitals, intravenous tubing is used to deliver medication in drops of various sizes ranging from 10 drops/mL to 60 drops/mL. A drop is abbreviated gtt, with gtts used for the plural. These abbreviations come from gutta, the Latin for drop.
A drop can also be used less formally as a unit of volume in recipes. According to some older kitchen references, 24 drops = ¼ teaspoon. Using U.S. definitions, this makes the drop equal to about 0.051 mL, making it quite comparable to the pharmacist's drop.
Unit of measure
Unit of measure may refer to:* Units of measurement for relevance to weights and measures* Unit of account for relevance in economics* Unit of Measure , a 2000 album by Tony Rice...
of volume
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
, the amount dispensed as one drop from a dropper
Pasteur pipette
Pasteur pipettes, also known as droppers or eye droppers, are used to transfer small quantities of liquids. They are usually glass tubes tapered to a narrow point, and fitted with a rubber bulb at the top. The combination of the Pasteur pipette and rubber bulb has also been referred to as a teat...
. It is often used in giving quantities of liquid drug
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
s to patients, and occasionally in cooking.
The volume of a drop is not well-defined: it depends on the device and technique used to produce the drop and on the physical properties of the fluid.
A water drop is a basic measurment. Create a dripping faucet or hose. Each drop must be a single unit; it cannot be a stream or have multiple drops coming together. Collect and count each drop using a small container calibrated in mL or ounces (1000 mL = 1 Liter and 29.6 mL = 1 fluid oz). The experiment shows that 5 drops of water equals 1 mL or about 150 drops equals 1-oz (US Fluid). A standard unit conversion gives (5.0 drops-water/1.0 mL-water) or (0.2 mL-water/1 drop-water).
There are several exact definitions of a "drop":
- the "metric" drop, 1/20 mL (50 μL).
- the medicalMedicineMedicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
drop, 1/12 mL (83⅓ μL). - the ImperialImperial unitThe system of imperial units or the imperial system is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The system came into official use across the British Empire...
drop, 1/36 of a fluidram (1/288 of an Imperial fluid ounceFluid ounceA fluid ounce is a unit of volume equal to about 28.4 mL in the imperial system or about 29.6 mL in the US system. The fluid ounce is distinct from the ounce, which measures mass...
, or 1/1440 of a gillGill (unit)The gill is a unit of measurement for volume equal to a quarter of a pint. It is no longer in common use, except in regard to the volume of alcoholic spirits measures but it is also kept alive by the occasional reference, such as in the cumulative song, "The Barley Mow".Imperial gillUnited States...
) (approximately 99 μL). - an alternate, possibly apocryphal, definition of the drop is 1/1824 of a gill (approximately 78 μL).
- the U.S. drop, 1/60 of a US fluidram, 1/80 of a teaspoonTeaspoonA teaspoon, an item of cutlery, is a small spoon, commonly part of a silverware place setting, suitable for stirring and sipping the contents of a cup of tea or coffee...
or 1/480 of a U.S. fluid ounce (approximately 62 μL). - an alternate definition of the U.S. drop is 1/96 of a teaspoon or 1/576 US fl oz (approximately 51 μL).
According to Webster dictionary, "drop" indicates the smallest volume of a liquid that may be measured. Drop size varies according to gravity, the density and the surface tension of the liquid.
In the past, a drop was another name for a minim. This meaning was used in Pharmacy
Pharmacy
Pharmacy is the health profession that links the health sciences with the chemical sciences and it is charged with ensuring the safe and effective use of pharmaceutical drugs...
to describe a volume equal to one 60th of a fluid dram or one 480th of a fluid ounce
Fluid ounce
A fluid ounce is a unit of volume equal to about 28.4 mL in the imperial system or about 29.6 mL in the US system. The fluid ounce is distinct from the ounce, which measures mass...
. This is equal to about 61.6 μL (U.S.) or 59.2 μL (Britain). Pharmacists have since moved to metric measurements, with a drop being rounded to exactly 0.05 mL (that is, 20 drops per milliliter). In hospitals, intravenous tubing is used to deliver medication in drops of various sizes ranging from 10 drops/mL to 60 drops/mL. A drop is abbreviated gtt, with gtts used for the plural. These abbreviations come from gutta, the Latin for drop.
A drop can also be used less formally as a unit of volume in recipes. According to some older kitchen references, 24 drops = ¼ teaspoon. Using U.S. definitions, this makes the drop equal to about 0.051 mL, making it quite comparable to the pharmacist's drop.