Baker’s Percentages Explained, in Plain English

The one rule: flour is 100%

Baker’s percentage is a way of writing recipes where the total flour always equals 100%, and everything else is measured against it. It is not a percentage of the whole dough — it’s a percentage of the flour. That’s the mental hurdle, and once you clear it the rest is arithmetic.

Because flour is the anchor, the numbers can add up to well over 100%. A focaccia at 80% hydration, 2% salt, and 6% oil totals 188%. That’s fine and expected — the percentages describe ratios relative to flour, not slices of a pie. The payoff is that you can compare any two recipes at a glance and scale a formula to any batch size without it ever going wrong.

How to convert a percentage into grams

The formula is: ingredient weight = flour weight × (ingredient percentage ÷ 100). If you have 1000 g of flour and want 75% hydration, that’s 1000 × 0.75 = 750 g of water. Salt at 2% is 1000 × 0.02 = 20 g. Oil at 8% is 1000 × 0.08 = 80 g. That’s the entire calculation, repeated for each ingredient.

To go the other way — from grams back to a percentage — divide the ingredient by the flour and multiply by 100. If a recipe lists 900 g flour and 720 g water, hydration is 720 ÷ 900 × 100 = 80%. This is how you reverse-engineer a recipe you like so you can scale or tweak it later.

This is also why serious bread recipes ask you to weigh in grams rather than measure in cups. A cup of flour can vary by 20% or more depending on how it’s scooped, which throws every ratio off. Weight makes the percentages true, and true percentages are what let a formula behave the same at 500 g or 5 kg of flour.

Reading a focaccia formula: what each number tells you

Hydration (water as a percent of flour) is the big lever for crumb. Focaccia typically lives between 70% and 85%; higher means a wetter dough and a more open, custardy crumb, lower means an easier-to-handle dough and a tighter crumb. Our hydration guide covers this in depth.

Salt is usually 2–2.5% of flour. Below about 1.5% the bread tastes flat and ferments a touch fast; much above 2.5% and it starts to taste salty and can slow the yeast. Oil in the dough is often 3–10%; it tenderizes the crumb and is separate from the generous oil you pour in the pan and on top, which isn’t always counted in the formula.

Yeast is written as a percentage too, and it’s small: roughly 0.3–1% instant yeast for focaccia, with the lower end used for long, cold ferments and the higher end for same-day bakes. Sourdough is expressed as inoculation — the starter as a percentage of flour — commonly 15–30%. Remember that a starter is part flour and part water, so it changes your real hydration; count both halves.

A full worked example

Say you want to build a classic focaccia formula: 100% flour, 78% water, 2% salt, 5% oil, 0.6% instant yeast. Pick a flour weight — start with 1000 g. Water: 1000 × 0.78 = 780 g. Salt: 1000 × 0.02 = 20 g. Oil: 1000 × 0.05 = 50 g. Yeast: 1000 × 0.006 = 6 g. Total dough weight is about 1856 g before pan oil.

Now scale it to fit a specific pan instead of a round flour number. Suppose you know from experience you want about 1200 g of dough for your tray. Your total percentage is 185.6%, so the flour needed is 1200 ÷ 1.856 = about 647 g. Run the same multiplications: water 505 g, salt 13 g, oil 32 g, yeast 3.9 g. The ratios — and therefore the character of the bread — are identical to the 1000 g version; only the batch size changed.

This is the real power of the method. You never memorize gram amounts for every pan size; you memorize one set of percentages and let the flour weight float to match your tin. Our recipes list the percentages alongside the grams so you can rescale any of them the same way.

Common mistakes and how to avoid them

The most frequent error is forgetting that a preferment or sourdough starter contributes both flour and water. If your recipe uses 200 g of 100%-hydration starter, that’s 100 g flour and 100 g water hiding inside your totals — leave them out of the math and your calculated hydration will be wrong, usually lower than reality.

The second is treating percentages as fractions of the whole dough; they’re fractions of the flour only. The third is mixing weight and volume — as soon as one ingredient is measured by cup or spoon rather than grams, the percentages stop being reliable. Weigh everything, anchor on flour, and the formula will behave predictably every time.