Baker's percentage

A bread formula written in weights only tells you about one bake. Written as percentages of the flour it tells you what kind of bread it is, and scales to any quantity without a second thought. The convention is old, industrial and slightly odd: the flour is 100%, every other ingredient is measured against it, and the column therefore adds up to well over a hundred. BAKERpedia states it plainly — "the weight of the flour is always 100%, and the total percent of all the other ingredients is always greater than 100%". Once you are used to it you can read a formula at a glance: 62% water is the pan bread in BAKERpedia's own worked example, 80% is a ciabatta, and the salt in that example is 2%. This page does the arithmetic in all three directions — weights to percentages, percentages to weights, and a dough weight back to the flour it starts from — and it splits a sourdough starter into the flour and water it is made of, because those belong in the totals rather than beside them.

How it is calculated

ingredient % = ingredient weight ÷ total flour weight × 100

That is the whole of it, and BAKERpedia's worked example is the check: 37.2 lb of water against 60.0 lb of flour is 62.0%, 1.2 lb of salt is 2.0%, and the seven lines together come to 176.0% for 105.6 lb of dough. Running it backwards is the same equation rearranged, which is how the batch mode works — "divide the desired or total batch weight by the total baker's percent (in decimal form). This gives the weight of flour." A starter is handled before any of this: at 100% hydration it is half flour and half water by definition, so 200 g of it adds 100 g to the flour and 100 g to the water, and the hydration you read is the dough's, not the mixing bowl's.

Source: BAKERpedia, "Baker's Percent" — "In baker's percent, the weight of the flour is always 100%, and the total percent of all the other ingredients is always greater than 100%."

Questions people ask

Why does my formula add up to more than 100%?

Because it is supposed to. Baker's percentage is not a share of the whole: every ingredient is measured against the flour, and the flour is one ingredient among several. A lean dough of flour, 70% water and 2% salt totals 172%, and there is nothing wrong with it. The number is still useful — it is what you divide a target dough weight by to get back to flour, which is exactly what the third mode here does.

Does the flour in my sourdough starter count?

Yes, and this is the single thing most hydration arguments are actually about. BAKERpedia describes a preferment as the case where "a portion of the total formula flour is fermented prior to mixing with dough ingredients" — the starter is not a separate ingredient sitting outside the formula, it is some of the formula's own flour and water, already mixed. So 200 g of a 100% starter moves 100 g into the flour total and 100 g into the water total, and a dough that looks like 65% hydration before the starter is counted usually is not. The page shows how much of your flour arrived that way, as a percentage.

What hydration should I use?

The number tells you what to expect rather than what to do. BAKERpedia puts it in terms of crumb: "80% hydration (8 parts water to 10 parts flour) often leads to an airy and irregular crumb such as in Italian Ciabatta bread while 60% hydration (6 parts water to 10 parts flour) yields denser and closed crumb similar to American-style bread." What the same percentage feels like in your hands also depends on the flour: a strong wheat flour or a whole grain drinks more water than a supermarket plain flour at the same number on the page.

I use two flours. Which one is the 100%?

Both, added together. BAKERpedia: "when multiple flours such as whole wheat, rye, cornmeal, or wheat patent are used in a formula as in the case of multigrain and high-fiber breads, the total weight of all flour- and grain-type ingredients is usually assigned to be 100%." Put the sum of your flours in the flour box. If you want to know what proportion of it is rye, that is a separate ratio and this page does not track it.

What units does this want?

One unit, consistently, and it does not matter which. A percentage is a ratio of two weights, so grams in gives grams out and pounds in gives pounds out — BAKERpedia's own worked example is in pounds. What it will not take is volume: a cup of flour and a cup of water are not comparable quantities, which is the reason bread formulas went to weight in the first place.

Why will it not give me a water weight?

If your starter percentage and its hydration between them carry more water than the hydration you asked for, there is no amount of water you can add to reach that figure — you would have to take some out. The page says so instead of printing a negative. Either lower the starter, use a stiffer starter, or accept the higher hydration.

Sources

The documents this page reads its numbers out of, linked so you can check them yourself.

1. BAKERpedia, "Baker's Percent" — "In baker's percent, the weight of the flour is always 100%, and the total percent of all the other ingredients is always greater than 100%."
2. BAKERpedia, "Preferment" — "In a preferment, a portion of the total formula flour is fermented prior to mixing with dough ingredients. The pre-fermented mixture contains flour, water and yeast/microorganisms."
3. BAKERpedia, "Sourdough Starter", typical formulation of a lean or basic starter — white flour from hard wheat 100.0 baker's %, water 80.0 (viscous, very loose dough) to 100.0 (almost liquid consistency), total 180.0 to 200.0

Related tools