How to Calculate Baker's Percentages

The short version

Baker's percentages describe every ingredient in a recipe as a share of the flour weight, and the flour is always 100% by definition. Water at 65% means the water weighs 65% as much as the flour; salt at 2% weighs 2% as much as the flour. Add up the percentages and you will usually land well over 100% — that is expected, because each ingredient is being compared to the flour, not to the whole batch. The baker's percentage calculator does this conversion instantly; the steps below show the hand method.

The formula, worked through a real recipe

The formula is one line: ingredient weight ÷ flour weight × 100. Take a simple lean bread recipe — 500 g flour, 325 g water, 10 g salt, 7 g yeast. Flour is 100% by definition. Water: 325 ÷ 500 × 100 = 65%. Salt: 10 ÷ 500 × 100 = 2%. Yeast: 7 ÷ 500 × 100 = 1.4%. Add them: 100 + 65 + 2 + 1.4 = 168.4% total, and the dough weighs 500 + 325 + 10 + 7 = 842 g. Nothing here is complicated — it is one division per ingredient, and the result is a formula that works at any batch size.

Why flour is the anchor

You might wonder why flour gets the honor of being 100% rather than the water, or the total. The answer is stability: the flour barely changes. A recipe's flour weight is its identity — a 500-gram-flour loaf and a 5-kilo-flour production batch are the same formula, just scaled. Water, on the other hand, varies constantly: a humid day, a thirstier flour, or a different bread style can all shift the water by tens of percent while the flour never moves. Anchoring to the one ingredient that stays put gives every baker, everywhere, the same reference point.

Hydration: the number that predicts your dough

The single most-read number in a baker's formula is the hydration — the water's percentage. It predicts how the dough will handle before you touch it:

The bands are guides, not laws — flour strength, mixing, and humidity all shift how a dough feels. Our default recipe sits at 65%, squarely in lean territory — a sandwich loaf or pizza dough that handles easily by hand.

Scaling recipes up or down

This is where percentages earn their keep. To resize a recipe, pick your new flour weight and apply it to every percentage: target flour × percentage ÷ 100. Suppose you want to double the default recipe to 1,000 g of flour. Water: 1,000 × 65 ÷ 100 = 650 g. Salt: 1,000 × 2 ÷ 100 = 20 g. Yeast: 1,000 × 1.4 ÷ 100 = 14 g. The ratios stay identical, so the bread behaves identically. Halving works the same way: 250 g of flour means 162.5 g of water. The recipe scaling calculator handles the arithmetic for you.

Preferments and sourdough starter

A sourdough starter (or any preferment — poolish, biga, levain) is part flour and part water, and percentages need it split into its two halves. A 200 g starter at 100% hydration is 100 g flour and 100 g water: add 100 g to the flour weight and 100 g to the water weight before you calculate. If 200 g of your 500 g flour and 325 g water comes from starter, the added flour is 400 g plus the starter's 100 g, and the added water is 225 g plus the starter's 100 g. The percentages still come out at 100% and 65%, but now they are honest.

Typical percentage ranges

Use these ranges as a sanity check on your own formulas — numbers far outside them usually mean a misweighed ingredient:

Common mistakes

Three errors cause most confusion. First, using volume instead of weight: a cup of flour can weigh 120 g or 160 g depending on the scoop, so weigh everything. Second, treating the percentages as shares of the whole: flour is 100% by definition, so the total always exceeds 100% — 168.4% in our example. Third, forgetting the starter's contribution: flour and water hiding inside a preferment still count.

The bottom line: weigh everything, call the flour 100%, and divide each ingredient by it — ingredient ÷ flour × 100. Scale with target flour × percentage ÷ 100. Run your own recipe through the baker's percentage calculator to see the percentages, hydration band, and dough total in one click.