Baker's percentage is a baker's notation method indicating the flour-relative proportion of ingredients used when making breads, cakes, muffins, and other pastries. It is also referred to as baker's math, or otherwise contextually indicated by a phrase such as based on flour weight. It is sometimes called formula percentage, a phrase that refers to the sum of a set of bakers' percentages.[note 1] Baker's percentage expresses each ingredient in parts per hundred as a ratio of the ingredient's mass to the total flour mass (that is, the unit mass).
For example, if a recipe calls for 10 pounds of flour and 5 pounds of water, the corresponding bakers' percentages will be 100% and 50%. Because of the way these percentages are stated, as a percent of flour mass rather than of all ingredients, the total will always exceed 100%.
Flour-based recipes are more precisely conceived as baker's percentage, and more accurately measured using mass instead of volume. The uncertainty in using volume measurements follows from the fact that flour settles in storage and therefore does not have a constant density.
Baker percentages 
A yeast-dough formula could call for the following list of ingredients, presented as a series of baker percentages:
There are several main conversions that are used with baker percentages. Converting baker percentages to ingredient weights is one, or using them. Converting known ingredient weights to baker percentages is another, or creating them. Conversion to true percentages, or based on total weight, is helpful to calculate an unknown flour weight from a desired total or formula weight.
Using baker percentages 
To derive the ingredient weights when any weight of flour is chosen:
- ingredient weight = flour weight × baker's percent(ingredient)⁄100%[note 2]
ingredient % weights
flour 100% X * 1.00 water 35% X * 0.35 milk 35% X * 0.35 fresh yeast 4% X * 0.04 salt 1.8% X * 0.018
In the example below, 2 lb and 10 kg of flour weights have been calculated. Depending on the desired weight unit, only one of the following four weight columns is used:
weights 2 lb 10 kg ingredient % lb oz kg g flour 100% 2 32 10 10000 water 35% 0.7 11.2 3.5 3500 milk 35% 0.7 11.2 3.5 3500 fresh yeast 4% 0.08 1.28 0.4 400 salt 1.8% 0.036 0.576 0.18 180
Creating baker percentages 
The baker has determined how much a recipe's ingredients weigh, and uses uniform decimal weight units. All ingredient weights are divided by the flour weight to obtain a ratio, then the ratio is multiplied by 100% for baker's percentage:
ingredient weight ingredient mass⁄flour mass × 100% flour 10 kg 10 kg÷ 10 kg= 1.000 = 100% water 3.5 kg 3.5 kg÷ 10 kg= 0.350 = 35% milk 3.5 kg 3.5 kg÷ 10 kg= 0.350 = 35% fresh yeast 0.4 kg 0.4 kg÷ 10 kg= 0.040 = 4% salt 0.18 kg 0.18 kg÷ 10 kg= 0.018 = 1.8%
Due to the canceling of uniform weight units, the baker may assign any desired system, metric or avoirdupois or other customary, to the flour weight when scaling and using bakers' percentages. Generally, the baker will find it easiest to use their balances' or scales' weight system.
Formula percentage and total weight 
flour 100% 56.88% water 35% 19.91% milk 35% 19.91% fresh yeast 4% 2.28% salt 1.8% 1.02% Total 175.8% 100%
The total or sum of the bakers' percentages is called the formula percentage. The sum of the ingredient weights is called the formula weight. The flour weight times the formula percentage also equals formula weight.
When each ingredient's bakers' percent is divided by the formula percentage, its multiplicative inverse, and all are expressed as percentages, their resulting sum equals 100%. When removing an ingredient from the list or adding one to it, or increasing or decreasing a bakers' percentage, the formula percentage changes. If it changes, the true percentages require recalculation.
A desired formula weight times the true percent of each ingredient equals the ingredients' respective weights. A desired formula weight times each ingredients' bakers' percent divided by the formula percentage also equals the ingredients' respective weights. Thus, it is not necessary to pre-calculate the true percentages, only the formula percentage.
Weights and densities 
The use of customary U.S. units can sometimes be awkward and the metric system makes these conversions simpler. In the metric system, there are only a small number of basic measures of relevance to cooking: the gram (g) for weight, the liter (L) for volume, the meter (m) for length, and degrees Celsius (°C) for temperature; multiples and sub-multiples are indicated by prefixes, two commonly used metric cooking prefixes are milli- (m-) and kilo- (k-). Intra-metric conversions involve moving the decimal point.
Common avoirdupois and metric weight equivalences:
- 1 pound (lb) = 16 ounces (oz)
- 1 kilogram (kg) = 1000 grams (g) = 2.20462262 lb [note 5]
- 1 lb = 453.59237 g = 0.45359237 kg
- 1 oz = 28.3495231 g.
In four different English-language countries of recipe and measuring-utensil markets, approximate cup volumes range from 236.59 to 284.1 milliliters (mL). Adaptation of volumetric recipes can be made with density approximations:
Volume to mass conversions for some common cooking ingredients ingredient density
U.S. customary cup
≈237 mL[note 7]
g oz g oz g oz water[note 8] 1[note 9] 249–250 8.8 283–284 10 236–237 8.3[note 10] granulated sugar 0.8 200 7.0 230 8.0 190 6.7 wheat flour 0.5–0.6 120–150 4.4–5.3 140–170 5.0–6.0 120–140 4.2–5.0 table salt 1.2 300 10.6 340 12.0 280 10.0
Due to volume and density ambiguities, a different approach involves volumetrically measuring the ingredients, then using scales or balances of appropriate accuracy and error ranges to weigh them, and recording the results. With this method, occasionally an error or outlier of some kind occurs.
Baker's percentages do not accurately reflect the impact of the amount of gluten-forming proteins in the flour on the final product and therefore may need to be adjusted from country to country, or even miller to miller, depending on definitions of terms like "bread flour" and actual protein content. Manipulation of known flour-protein levels can be calculated with a Pearson square.
In home baking, the amounts of ingredients such as salt or yeast expressed by weight may be too small to measure accurately on the scales used by most home cooks. For these ingredients it may be easier to express quantities by volume, based on standard densities. Many breadmaking books targeted to home bakers will provide both percentages and volumes for common batch sizes, for this reason.
Besides the need for appropriate scales, a kitchen calculator is helpful when working directly from baker's percentage.
Baker's percentage enables the user to:
- compare recipes more easily (i.e. which are drier, saltier, sweeter, etc.);
- spot bad recipes or predict their baked characteristics;
- alter or add a single-ingredient percentage without changing the other ingredients' percentages;
- uniformly measure ingredients such as eggs, commonly used in baking, where the quantity per unit may vary;
- accurately and easily scale for different batch sizes.
Common Formulations 
Common formulations for bread include 100% flour, 60% water/liquid, 1% yeast, 2% salt and 1% oil, lard or butter. The amount of water, expressed as a percentage of the weight of flour, is referred to as the "hydration" and is indicative of the stickiness of the dough and the "crumb", or internal texture, of the bread. Lower hydration rates (e.g. 50-57%) are typical for bagels and pretzels, and medium hydration levels (58-65%) are typical for breads, and rolls. Higher hydration levels are used to produce more and larger holes, as is common in artisan breads such as baguettes or Ciabatta.
- † Except for creams and custards, when the formula includes milk, bakers almost always use high-heat NFDM (non-fat dry milk). In breads the usage is typically within a range of 5%-12%; fresh whole milk is 3.5% milk fat, 88% water, and 8.5% milk solids.
- †† A yeast flavor in the baked bread is generally not noticeable when the bakers' percent of added yeast is less than 2.5%.
- There is some ambiguity regarding the use of the phrase "formula percentage" in the literature. From the published date of 2004 to the date 2007, Hui's definitions have changed slightly. In 2004 "formula percent" was defined by "total weight of all ingredients"; however by the latter date's usage, the preference was to use the prefix "true" in the phrase "True formula percent (true percent)" when referring to "total weight of all ingredients." In 2005, Ramaswamy & Marcotte used the phrase "typical formula" in reference to a "baker's %" series of ingredients, then drew the semantic and mathematic distinctions that "actual percentage" was one based upon "total mass", which they labelled "flour %", "water %", etc. In 2010, Figoni said that "baker's percentage" was "sometimes called formula percentage...." In 1939, the phrase formula percentage was said to commonly refer to the sum of the particular percentages that would later be called bakers' percentages.
- Derived algebraically from Gisslen's formula.
- X denotes a flour weight. In this column the percentage was divided by 100%. When using a calculator, pressing the "%" key usually divides by 100. When using a spreadsheet, formatting the cell as percentage versus number automatically handles the per-cent portion of the calculation.
- True percent values have been rounded and are approximate.
- It's worth noting the multiplicative inverse of 2.20462262.
- One gram per millilitre is very close to one avoirdupois ounce per fluid ounce: 1 g/mL ≈ 1.002 av oz/imp fl oz This is not a numerical coincidence, but comes from the original definition of the kilogram as the mass of one litre of water, and the imperial gallon as the volume occupied by ten avoirdupois pounds of water. The slight difference is due to water at 4 °C (39 °F) being used for the kilogram, and at 62 °F (17 °C) for the imperial gallon. The U.S. fluid ounce is slightly larger.
- 1 g/mL ≈ 1.043 av oz/U.S. fl oz
- From cup (unit). Note the similarity of cup mL to water weight or mass as g. This density relationship can also be useful for determining unknown volumes.
- 1 g/mL is a good rough guide for water-based liquids such as milk (the density of milk is about 1.03–1.04 g/mL).
- The density of water ranges from about 0.96 to 1.00 g/mL dependent on temperature and pressure. The table above assumes a temperature range 0–30 °C (32–86 °F). The variation is too small to make any difference in cooking.
- Since an imperial cup of water weighs approximately 10 avoirdupois ounces and five imperial cups are approximately equal to six U.S. cups, one U.S. cup of water weighs approximately 8⅓ avoirdupois ounces.
- Paula I. Figoni (2010). How Baking Works: Exploring the Fundamentals of Baking Science. New York: Wiley. pp. 9–11. ISBN 0-470-39267-3. Retrieved 2010 Dec 06. "Baker's percentage—sometimes called formula percentage or indicated as "on flour weight basis"—is different from the percentages commonly taught in math classes."
- Griffin, Mary Annarose; Gisslen, Wayne (2005). Professional baking (4th ed.). New York: John Wiley. p. 10. ISBN 0-471-46427-9. Retrieved 2011 Jan 1.
- Corriher, Shirley (2008). BakeWise: The Hows and Whys of Successful Baking with Over 200 Magnificent Recipes. New York: Scribner. p. 32. ISBN 1-4165-6078-5. Retrieved 2010 Dec 9.
- Hui, Yiu H. (2006). Handbook of food science, technology, and engineering. Washington, DC: Taylor & Francis. p. 16-6. ISBN 0-8493-9849-5. Retrieved 2010 Dec 9.
- Laura Halpin Rinsky; Glenn Rinsky (2009). The pastry chef's companion: a comprehensive resource guide for the baking and pastry professional. Chichester: John Wiley & Sons. p. 19. ISBN 0-470-00955-1. Retrieved 2010 Dec 9.
- Daniel T. DiMuzio (2009). Bread Baking: An Artisan's Perspective. New York: Wiley. p. 31. ISBN 0-470-13882-3. Retrieved 2010 Dec 11.
- Cauvain, Stanley P. (2003). Bread making: improving quality. Boca Raton: CRC Press. p. 475. ISBN 1-85573-553-9. Retrieved 2010 Dec 8. "Generally the taste of yeast itself is not detectable in bread unless the amount of yeast used is greater than 2.5% based on the weight of flour."
- J. Scott Smith, Yiu H. Hui, ed. (2004). Food processing: principles and applications. Cambridge, MA: Blackwell Pub. p. 178. ISBN 0-8138-1942-3. Retrieved 2010 Dec 29. "Formula—term used instead of "recipe," by the baking industry; the weight of each ingredient is determined based on the weight of flour at 100%.
Formula percent—term used by the baking industry to describe the amount of each ingredient by weight for a "recipe" or formula compared to the weight of all ingredients."
- Yiu H. Hui, ed. (2007). Handbook of food products manufacturing. New York: Wiley. p. 302. ISBN 0-470-12524-1. Retrieved 2010 Dec 29. "True formula percent (true percent): Term used by the baking industry to describe the amount of each ingredient by weight for a "recipe" or formula compared with the total weight of all ingredients."
- Michele Marcotte; Hosahalli Ramaswamy (2005). Food Processing: Principles and Applications. Boca Raton: CRC. pp. 14–15. ISBN 1-58716-008-0. Retrieved 2010 Dec 25.
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