Cooking weights and measures
For most of history, most cookbooks did not specify quantities precisely, instead talking of "a nice leg of spring lamb", a "cupful" of lentils, a piece of butter "the size of a walnut", and "sufficient" salt.1 Informal measurements such as a "pinch", a "drop", or a "hint" (soupçon) continue to be used from time to time. In the US, Fannie Farmer introduced the more exact specification of quantities by volume in her 1896 Boston Cooking-School Cook Book.
Today, most of the world prefers metric measurement by weight, though the preference for volume measurements continues in the United States ("almost exclusively"),2 North America, Australia, and Sweden.3 Different ingredients are measured in different ways:
Liquid ingredients are generally measured by volume worldwide.
Dry bulk ingredients, such as sugar and flour, are measured by weight in most of the world ("250 g flour"), and by volume in North America and Australia ("1/2 cup flour"). Small quantities of salt and spices are generally measured by volume worldwide, as few households have sufficiently precise balances to measure by weight.
Meats are generally specified by weight or count worldwide: "a 2 kg chicken"; "four lamb chops".
Eggs are usually specified by count. Vegetables are usually specified by weight or occasionally by count, despite the inherent imprecision of counts given the variability in the size of vegetables.
In most of the world, recipes use the metric system of units—litres (L) and millilitres (mL), grams (g) and kilograms (kg), and degrees Celsius (°C). The spelling "litre" is the British (and French) spelling, the US (and German) spelling is "liter".
The USA measures weight in pounds (avoirdupois), while recipes in the UK, following the advice of the Guild of Food Writers, tend to be first in metric quantities and in pounds and ounces or may exclusively be in metric.4 The USA also uses volume measures based on cooking utensils and pre-metric measures. The actual values frequently deviate from the utensils on which they were based, and there is little consistency from one country to another.
The volumetric measures here are for comparison only. See below for the definition of Gallon for more details.
In addition, the "cook's cup" above is not the same as a "coffee cup" which can vary anywhere from 100 to 200 mL (3.5 to 7.0 imp fl oz; 3.4 to 6.8 US fl oz), or even smaller for espresso.
In Australia – since 1970 – metric utensil units have been standardized by law and imperial measures no longer have legal status. However – it is wise to measure the actual volume of the utensil measures – particularly the 'Australian tablespoon' – see above – since many are imported from other countries with different values. Dessertspoons are standardized as part of the metric system at 10 mL, though they are not normally used in contemporary recipes. Australia is the only metricated country with a metric tablespoon of 20 mL, unlike the rest of the world, which has a 15 mL metric tablespoon.
In Europe older recipes frequently refer to pounds (e.g. Pfund in German, pond in Dutch, livre in French). In each case, the unit refers to 500 g, about 10% more than an avoirdupois pound (454 g). Dutch recipes may also use the ons, which is 100 g.
With the advent of accurate electronic scales it has become more common to weigh liquids for use in recipes, avoiding the need for accurate volumetric utensils.678 The most common liquids used in cooking are water and milk, milk weighing approximately the same as water in the low volumes used in cooking.
1 mL of water weighs 1 gram so a recipe calling for 300 mL (≈ ½ Imperial Pint) of water can simply be substituted with 300 g (≈ 10 oz.) of water.
1 fluid ounce of water weighs approximately 1 ounce so a recipe calling for a UK pint (20 fl oz) of water can be substituted with 20 oz of water.
More accurate weight equivalents become important in the large volumes used in commercial food production. To an accuracy of five significant digits, they are:
at 4.0 °C (39.2 °F)
|1 fl.oz. UK||28.413||1.0022|
|1 fl.oz. US||29.574||1.0432|
|1 pint US||473.18||16.691|
|1 pint UK||568.26||20.045|
Even a home cook can use greater precision at times. Water at 4.0 °C (39.2 °F) may be volumetrically measured then weighed to determine an unknown measuring-utensil volume9 without the need for a density adjustment.10
|Ingredient||Density (g/mL or av.oz./fl.oz.)|
The US uses pounds and ounces (avoirdupois) for weight, and US customary units for volume. For measures used in cookbooks published in other nations navigate to the apropos regional section in Traditional measurement systems.
Measures are classified as either dry measures or fluid measures. Some of the fluid and dry measures have similar names, but the actual measured volume is quite different. A recipe will generally specify which measurement is required. U.S. recipes are commonly in terms of fluid measures.
|teaspoon||tsp. or t.||1⁄3 tbsp.||1⁄6||4.93|
|tablespoon||tbsp. or T.||1⁄2 fl.oz.||1⁄2||14.79|
|fluid ounce||fl.oz. or oz.||1⁄128 gal.||1||29.57|
|fifth 11||—||1⁄5 gal.||25.36||750|
|gallon 11||gal.||231 in3||128||3,785.41|
|pint, dry||pt.||1⁄2 dry qt||33.60||550.61|
|quart, dry||qt.||1⁄8 peck||67.20||1,101.22|
|bushel 11||bu||684.5π in3||2,150.42||35,239.07|
Dashes, pinches, and smidgens are all traditionally very small amounts well under a teaspoon, but not more uniformly defined. In the early 2000s some companies began selling measuring spoons that defined a dash as 1⁄8 teaspoon, a pinch as 1⁄16 teaspoon, and a smidgen as 1⁄32 teaspoon.1213 Based on these spoons, there are two smidgens in a pinch and two pinches in a dash.
In domestic cooking, bulk solids, notably flour and sugar, are measured by volume, often cups, though they are sold by weight at retail. Weight measures are used for meat. Butter may be measured by either weight (1⁄4 lb) or volume (3 tbsp) or a combination of weight and volume (1⁄4 lb plus 3 tbsp); it is sold by weight but in packages marked to facilitate common divisions by eye. (As a sub-packaged unit, a stick of butter, at 1⁄4 lb [113 g], is a de facto measure in the US)
Cookbooks in Canada use the same system, although pints and gallons would be taken as their Imperial quantities unless specified otherwise. Following the adoption of the metric system, recipes in Canada are frequently published with metric conversions.
Note that measurements in this section are in imperial units
Traditional British measures distinguish between weight and volume.
- Weight is measured in ounces and pounds (avoirdupois) as in the U.S.
- Volume is measured in Imperial gallons, quarts, pints, and fluid ounces. The Imperial gallon was originally defined as 10 pounds (4.5359 kg) of water in 1824, and refined as exactly 4.54609 litres in 1985. Older recipes may well give measurements in cups; insofar as a standard cup was used, it was usually 1⁄2 pint [~285 mL] (or sometimes 1⁄3 pint [~190 mL]), but if the recipe is one that has been handed down in a family, it is just as likely to refer to someone's favourite kitchen cup as to that standard.
|Unit||Ounces||Pints||Millilitres||Cubic inches||US ounces||US pints|
|fluid ounce (fl oz)||1||1⁄20||28.4130625||1.7339||0.96076||0.060047|
|Note: The millilitre figures are exact whereas the cubic-inch and US measure figures are to five significant digits.|
|Note 2: The Imperial Gallon is equal to 10 lbs of water.|
American cooks using British recipes, and vice versa, need to be careful with pints and fluid ounces. A US pint is 473 mL, while a UK pint is 568 mL, about 20% larger. A US fluid ounce is 1⁄16 of a US pint (29.6 mL); a UK fluid ounce is 1⁄20 UK pint (28.4 mL). This makes an Imperial pint equivalent to 19.2 US fluid ounces.
On a larger scale, perhaps for institutional cookery, an Imperial gallon is eight Imperial pints (160 imp fl oz, 4.546 litres) whereas the US gallon is eight US pints (128 US fl oz, 3.785 litres).
The metric system was officially adopted in the UK, for most purposes, in the 20th century and both imperial and metric are taught in schools and used in books. It is now mandatory for the sale of food to also show metric. However, it is not uncommon to purchase goods which are measured and labeled in metric, but the actual measure is rounded to the equivalent imperial measure (i.e., milk labeled as 568 mL / 1 pint). In September 2007, the EU with Directive 2007/45/EC deregulated prescribed metric packaging of most products, leaving only wines and liqueurs subject to prescribed EU-wide pre-packaging legislation;141516 the law relating to labelling of products remaining unchanged.
Volume measures of compressible ingredients have a substantial measurement uncertainty, in the case of flour of about 20%.17 Some volume-based recipes, therefore, attempt to improve the reproducibility by including additional instructions for measuring the correct amount of an ingredient. For example, a recipe might call for "1 cup brown sugar, firmly packed", or "2 heaping cups flour". A few of the more common special measuring methods:
- Firmly packed
- With a spatula, a spoon, or by hand, the ingredient is pressed as tightly as possible into the measuring device.
- Lightly packed
- The ingredient is pressed lightly into the measuring device, only tightly enough to ensure no air pockets.
- Even / level
- A precise measure of an ingredient, discarding all of the ingredient that rises above the rim of the measuring device. Sweeping across the top of the measure with the back of a straight knife or the blade of a spatula is a common leveling method.
- Allowing a measure of an ingredient to pile up above the rim of the measuring device naturally, into a soft, rounded shape.
- Heaping / heaped
- The maximum amount of an ingredient which will stay on the measuring device.
- This instruction may be seen in two different ways, with two different meanings: before the ingredient, as "1 cup sifted flour", indicates the ingredient should be sifted into the measuring device (and normally leveled), while after the ingredient, as "1 cup flour, sifted", denotes the sifting should occur after measurement.
Such special instructions are unnecessary in weight-based recipes.
- Schofield, Mary Anne (1989). Cooking by the book: food in literature and culture. Bowling Green, OH: Bowling Green State University Popular Press. p. 8. ISBN 0-87972-443-9. Retrieved 2011 April 20. "An example is Lydia M. Child. The Frugal Housewife provides recipes of the "butter the size of a walnut, a good handful of sugar, bake until done" variety along with...."
- Gisslen, Wayne (2010). Professional Cooking, College Version. New York: Wiley. p. 107. ISBN 0-470-19752-8. Retrieved 2011 April 20. "The system of measurement used in the United States is complicated. Even when people have used the system all their lives, they still sometimes have trouble remembering things like how many fluid ounces are in a quart or how many feet are in a mile. ... The United States is the only major country that uses almost exclusively the complex system of measurement we have just described."
- "Metrication". Guild of Food Writers. 2013. Retrieved 5 April 2013.
- "Food and Drugs: FDA Food Labeling". U.S. Government Printing Office. April 1, 2004.
For Nutrition facts labeling "a teaspoon means 5 milliliters (mL), a tablespoon means 15 mL, a cup means 240 mL, 1 fl oz means 30 mL, and 1 oz in weight means 28 g."
- Scott, Alan; Daniel Wing (1999). The Bread Builders: Hearth Loaves and Masonry Ovens. Chelsea Green Publishing Company. p. 30. ISBN 1-890132-05-5. Retrieved 2010 Dec 15. "Weight is more convenient and accurate than volume for measuring ingredients and is universally used in bakeries. Electronic scales can be set back to zero after each ingredient is added...."
- Griffin, Mary Annarose; Gisslen, Wayne (2005). Professional baking (Fourth ed.). New York: John Wiley. p. 6. ISBN 0-471-46427-9. Retrieved 2010 Dec 15. "Volume measure is often used when scaling water for small or medium-sized batches of bread. Results are generally good. However, whenever accuracy is critical, it is better to weigh."
- Rees, Nicole; Amendola, Joseph (2003). The baker's manual: 150 master formulas for baking. London: J. Wiley. p. 11. ISBN 0-471-40525-6. Retrieved 2010 Dec 15. "Weighing the water and other liquids like milk also ensures accuracy, especially when increasing batch sizes."
- C.A. Street (1997). Flour Confectionery Manufacture. New York: Wiley-Interscience. p. 146. ISBN 0-471-19817-X. Retrieved 2011 April 28. "The volume of the cup can be measured by filling it with water at 4°C (39°F) and weighing. At this temperature, the weight of water in grams will equal the volume of the cup in millilitres."
- "Water Density Calculator".
- Rowlett, Russ (July 11, 2005). "How Many? A Dictionary of Units of Measurement". University of North Carolina at Chapel Hill.
The "fifth", originally exactly one-fifth US gallon (=25.6 US fl oz, ≈757 mL) was adjusted slightly to make it exactly 750 mL (≈25.36 US fl oz). It is normally only used as a retail measure of wine and liquor.
Volume measures in the United States are based on the U.S. gallon for fluids (legally defined as 231 cubic inches (≈ 3.785 litres)), and the US bushel for dry goods (legally defined as an 8-inch tall cylinder 18.5 inches in diameter (≈ 35.24 litres)).
- Rowlett, Russ (December 2003). "P". How Many? A Dictionary of Units of Measurement. University of North Carolina at Chapel Hill.
- "Pinch, Dash and Smidgen Measurements". Internet Accuracy Project. 2009.
- "Legal metrology and pre-packaging – Pre-packaging – Pack sizes". European Commission – Enterprise and Industry. Retrieved 28 March 2012.
- "Government response to the consultation on specified quantities – Non pre-packages and food information". London: National Measurement Office, Department for Business Innovation and Skills. September 2009. Retrieved 28 March 2012.
- "Guidance note on UK implementation of a European directive deregulating specified quantities (fixed pack sizes)". National Weights and Measures Laboratory, an Executive Agency of the Department for Innovation, Universities and Skills. January 2009. Retrieved 28 March 2012.
- L. Fulton, E. Matthews, C. Davis: Average weight of a measured cup of various foods. Home Economics Research Report No. 41, Agricultural Research Service, United States Department of Agriculture, Washington, DC, 1977.
- The Weight of Water from Fourmilab Switzerland
- Canadian Weights and Measures Act ( R.S., 1985, c. W-6 )
- Australian National Measurement Regulations 1999
- UK Weights and Measures Act 1985 (1985 c. 72)
- U.S. NIST Guide to SI Units metric conversions → see Appendix B.9
- U.S. NIST Household Weights and Measures Chart Abbreviated or rounded figures.