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Common Measurement Conversions

Medically reviewed by C. Fookes, BPharm Last updated on Oct 29, 2019.

There are several measurement systems in use around the world and it can be daunting trying to convert a foreign measurement into one you are familiar with. To add to the confusion, some abbreviations for these measurements sound similar, yet the quantity may differ by a thousand. This article explains some of the more common conversions and abbreviations.

Conversion Calculator

Use this Conversion Calculator to convert between commonly used units.

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Liquid Measurement Conversions

How many ml in a teaspoon? How many fluid ounces in one liter? If you are giving any type of liquid, you may be seeking the answers to these questions.

But the answer may not be as straightforward as saying one teaspoon equals 5mL. Using a kitchen spoon to measure the dose of medicine is NOT a good idea unless it has been properly calibrated or sold as a kitchen measure. Teaspoons and tablespoons are NOT official measurements and most of the silverware and cutlery that you buy to eat with has not been standardized to the same volume, and actual teaspoon volumes may range from 2.5mL to 7mL. Measuring a dose with the cutlery you use to eat with will likely result in either an underdose or an overdose of the medicine.

Which is why you should always use a dosing cup, syringe, or measuring spoon. These are often supplied free with liquid medicines, but, if not, can be bought from a pharmacy and most supermarkets. Always use a properly calibrated measuring device to measure liquid medicines.

Note: Fluid ounces are a measure of volume while ounces are a measure of weight.

Quantity Conversion
½ teaspoon 2.5 mL
1 teaspoon 5 mL
2 teaspoons 10 mL
½ tablespoon 7.5 mL
1 tablespoon 15 mL
3 teaspoons 1 tablespoon
1 liter 1000 mL
1 fluid ounce 30 mL*
1 pint 473 mL*
1 gallon 3785 mL*
* Approximately

Abbreviations

  • Teaspoon = tsp
  • Tablespoon = Tbsp or Tb
  • Milliliter = mL
  • Liter = L
  • Fluid ounce = fl oz
  • Pint = pt
  • Gallon = gal

Solid Measurement Conversions

How many mcg in an mg? How many mg in an oz? Measurement conversions for solids can be confusing, particularly when many of the units sound the same.

Quantity Conversion
1000 micrograms 1 milligram
1000 milligrams 1 gram
1000 grams 1 kilogram
1 kilogram 2.2 pounds
1 ounce 28,300 milligrams
1 ounce 28.3 grams
1 pound 16 ounces
1 pound 454 grams
1 pound 0.45 kilograms
1 stone 14 pounds
1 stone 6.35 kilograms

Abbreviations

  • Microgram = mcg (may also be written µgm)
  • Milligram = mg
  • Gram = gm
  • Kilogram = kg
  • Ounces = oz
  • Pounds = lbs

Temperature Measurement Conversions

The Fahrenheit scale for temperature is only used in the United States and its associated colonies, although Canada still retains it as a supplementary scale.

To convert Fahrenheit to Celsius, take the Fahrenheit temperature and subtract 32, then multiply this number by 5, then divide the answer by 9 to obtain the temperature in degrees Celsius.

To convert Celsius to Fahrenheit, take the Celsius temperature and multiply it by 1.8, then add 32 to obtain the temperature in degrees Fahrenheit.

The Celsius and Fahrenheit scales meet at -40°. Above -40°, Fahrenheit temperatures are always higher than corresponding Celsius temperatures, and below -40°, Fahrenheit temperatures are lower than the corresponding Celsius temperatures.

Temperature Conversion
-40°C -40°F
-17.8°C 0°F
0°C 32°F
30°C 86°F
100°C 212°F

Abbreviations

  • Celsius = C
  • Fahrenheit = F

The Kelvin Temperature Scale

The Kelvin temperature scale is called an absolute temperature scale because it begins at zero and progresses in only one direction (there are no negative temperatures in the Kelvin scale).

The zero point of the Kelvin scale is absolute zero, which is the theoretical temperature at which molecules of a substance have their lowest kinetic energy and cannot get any colder. The Kelvin scale is defined using the third law of thermodynamics.

The Kelvin scale is related to the Celsius scale but is conventionally written without the degree symbol. Zero kelvin (written 0k) corresponds to −273.15°C on the Celsius temperature scale.  

The Kelvin scale is mainly used for scientific temperature measurement because it allows many physical laws and formulas to be expressed more simply. The kelvin is the base unit of temperature in the International System of Units (SI). It is named after British mathematician and physicist William Thomson Kelvin, who proposed it in 1848.

Kelvin Celsius
0 -273.15
273.15 0
373.15 100

Note that 1 kelvin has the same magnitude as 1 degree Celsius, as seen by the difference between the freezing and boiling points of water of 100 degrees Celsius (or 100 kelvins).

See Also

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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