Baker's Percentage Explained: Hydration, Salt, and Scaling Any Recipe

The first time I saw a bread formula written as "water 70%, salt 2%, yeast 1%," I assumed those numbers had to add up to 100 and that something was missing. They don't, and nothing is. Baker's percentage is a small idea that fixes a real problem: recipes written in fixed grams only work at one batch size, and the moment you want a smaller test loaf or a bigger production run, you have to re-derive every number by hand. Once flour becomes your anchor, scaling stops being arithmetic and becomes a single multiplication.

Flour Is Always 100%

The whole system rests on one rule: flour is the reference, and you call it 100%. Every other ingredient is then expressed as a percentage of the flour weight, not as a percentage of the dough. That is why the numbers run past 100 — they are parts of the flour, not slices of a pie.

The formula for any ingredient is short:

ingredient % = (ingredient weight ÷ flour weight) × 100

So if a dough uses 1000 g of flour and 700 g of water, the water is (700 ÷ 1000) × 100 = 70%. Salt at 20 g is (20 ÷ 1000) × 100 = 2%. Yeast at 10 g is 1%. Add those up and you get 173%, which feels wrong until you remember that flour itself is the 100 those others are measured against. A dough that reads 70% / 2% / 1% is completely normal. If you force everything to sum to 100, you will starve the dough of water and end up with a brick.

Hydration Is Just the Water Percentage

Hydration is the single number bakers argue about most, and it is nothing more than the water expressed as a baker's percentage. Water weight divided by flour weight, times 100.

With 700 g of water and 1000 g of flour, hydration is 700 ÷ 1000 × 100 = 70%. That tells you, before you ever touch the dough, what kind of bread you're aiming at:

60–65% — firm sandwich-bread dough that shapes easily on the bench.
70% — a workable artisan loaf with an open but manageable crumb.
75–80% — wet ciabatta and focaccia territory, handled with wet hands and folds rather than kneading.

The percentage gives you a target you can hit on a scale instead of chasing by feel. Two recipes also become directly comparable: a 65% loaf and a 75% loaf differ by exactly ten points of water, and that gap alone explains a tighter crumb versus an open one.

One trap worth flagging: if you build with sourdough starter or levain, count both its flour and its water. A 100% hydration starter is half flour, half water. Fold in 200 g of it and you've added 100 g of flour and 100 g of water to your totals. Leave that flour out of the denominator and your real hydration reads higher than the dough actually is. The Baker's Percentage Calculator handles this by summing every row tagged as flour and every row tagged as water, so multi-flour and starter-heavy doughs still report one clean hydration figure.

A Worked Example: A 70% Hydration Dough

Let's make the math concrete with a classic country loaf.

Flour: 1000 g → 100% (the anchor)
Water: 700 g → 70% hydration (700 ÷ 1000 × 100)
Salt: 20 g → 2% (20 ÷ 1000 × 100)
Yeast: 10 g → 1% (10 ÷ 1000 × 100)

Total dough weight is 1730 g. Read it back as a formula and you have something portable: 100% flour, 70% water, 2% salt, 1% yeast. Nothing in that line is tied to the number 1000 — it describes the relationships, which is exactly what you need to rebuild the dough at any size.

Why salt at 2% and yeast at 1%? Salt between 1.8% and 2.2% of the flour is the band where bread tastes seasoned without tasting salty, and where it still tightens the gluten and slows fermentation enough to keep proofing under control. Instant yeast around 1% gives a normal room-temperature rise; halve it for a slow overnight bulk, or swap in roughly 20% starter for a sourdough version. Type 2 and 1 against your flour weight and you get the exact grams to weigh — no guessing.

Scaling a Recipe to Any Flour Weight

This is where baker's percentage earns its keep. Because every amount is anchored to flour, scaling is one operation: pick a new flour weight and multiply each percentage by it.

Say your house formula is 100% flour, 72% water, 2% salt, and you want a single 250 g test loaf instead of the usual kilo. Set flour to 250 g and:

Water: 250 × 0.72 = 180 g
Salt: 250 × 0.02 = 5 g

The ratios never drift, so the test bake behaves like the full batch instead of a guess. Going the other way works identically — enter 12000 g of flour for a market-stall batch and the same percentages print every ingredient in grams for the day's mix. The crumb and flavor stay the same because the relationships stayed the same.

I lean on this constantly. I'll free-hand a bake that comes out great, then type the grams I actually used back into the tool to recover the percentages, and only then do I have a formula I can trust to repeat. Reverse-engineering a one-off into a real recipe is half of why I keep the calculator open while I bake. If you're scaling things that aren't bread — syrups, brines, or anything ratio-based — a general-purpose percentage calculator covers the same multiply-by-a-percent move without the baking-specific tagging.

Keep the Two Modes Straight

The most common avoidable error is mixing the two directions of the calculation. Weights-to-percentages is for when you have grams and want to discover the formula. Percentages-to-weights is for when you have a formula and want grams. Typing a percentage into a weight field, or a gram value into a percent field, produces a number that looks plausible and means nothing. Keep each column in its own unit and the tool will keep you honest.

Once the formula language clicks, you stop thinking in fixed recipes and start thinking in ratios — which is how professional bakers have always worked. Flour at 100%, water as hydration, salt and yeast as small percentages, and a single multiplication standing between a test loaf and a full production batch.

Made by Toolora · Updated 2026-06-13