Baker's Percentage: The One Concept That Makes Every Recipe Make Sense

You've been baking sourdough for a while. You're comfortable with the process, you know how your dough feels. Then one day a recipe hits you with this:

• 78% hydration
• 2% salt
• 20% starter

And suddenly bread looks less like dinner and more like homework.

It's not. Baker's percentage is the simplest trick in the bakery, and once it clicks you'll never read a recipe the same way again. Ten minutes from now you'll be calculating it in your head.

Why bakers talk in percentages

Here's the problem with writing recipes in grams: the numbers only work for one batch size.

Say you find a recipe for 500g of flour and you want to make four loaves instead of one. Now you're doing division and multiplication on every single ingredient, trying not to lose track of a decimal. It's annoying. It's also how mistakes happen.

Percentages fix this. When a recipe is written in baker's percentage, the ratio between every ingredient is locked in. Scale the flour up or down, and you know exactly how much of everything else you need. No recalculating from scratch. No mystery.

There's a second benefit: comparing recipes. Two sourdough recipes can look totally different in grams but be almost identical when you look at the percentages. Seeing "both are 73% hydration and 2% salt" tells you a lot more than comparing 450g versus 750g of water.

This is why every professional baker thinks in percentages. And once you do too, you'll be able to look at any recipe and immediately understand what kind of bread it'll make.

The one rule of baker's percentage

Ready? Here it is:

Flour is always 100%. Every other ingredient is calculated as a percentage of the total flour weight.

That's it. That's the whole system.

If you have 1000g of flour, salt is calculated as a percentage of 1000g. Water is calculated as a percentage of 1000g. Starter is calculated as a percentage of 1000g. The flour is the anchor, and everything else hangs off it.

The baker's percentage formula is:

That's all there is to how to calculate baker's percentage. Plug any ingredient into that formula and you've got its share.

So if your recipe has 1000g flour and 750g water:

If it has 20g salt:

That's baker's math. You can do this with any recipe, any ingredient, any batch size.

Calculator

Run this in the calculator

single-loaf recipe entry with live baker's percentage readout below every ingredient field. User types weights, percentages appear instantly

Open calculator

If you want to play with a recipe right now, the baker's percentage calculator will run these numbers for you as you type.

A worked example: from grams to percentages

Let's take a real sourdough recipe and pull it apart.

The recipe:

• 500g bread flour
• 375g water
• 10g salt
• 100g starter

Step one: flour is 100%. Always. So our anchor is 500g = 100%.

Now we calculate everything else the same way:

75% water is your hydration. On the wetter side of average. Sticky but workable. 2% salt is right in the sweet spot. Most sourdough recipes land between 1.8% and 2.2%. 20% starter is a fairly active, moderately fast ferment.

So the full recipe in baker's percentage is: 100% flour / 75% water / 2% salt / 20% starter.

Now here's the cool part. Someone else baking from that same percentage recipe can make it at any size. 800g flour? 300g flour? The percentages tell them exactly what to do.

Calculator

Run this in the calculator

Pre-filled with 500g flour, 375g water, 10g salt, 100g starter. Adjust any value and watch the percentages update.

Open calculator

"Wait, my total is 197%?"

Yes. And that's completely fine.

This trips up almost every beginner. You add up 100% + 75% + 2% + 20% and get 197%. Or you add the grams and divide by the total. Either way, you're looking at a number that's not 100% and wondering what went wrong.

Nothing went wrong.

Baker's percentages don't add up to 100%. They're not slices of a pie. They're all individual ratios against one anchor: the flour.

Think of it like this. The flour is your ruler. You're not measuring how much of the total each ingredient takes up. You're measuring how big each ingredient is compared to the ruler. The ruler itself is always 12 inches (or 100%), and every other measurement is just relative to it.

So yes, your total will be well over 100%. That's correct. That's expected. If it ever added up to exactly 100%, something would be off.

Going the other way: percentages to grams

This is where baker's percentage gets genuinely useful for day-to-day baking.

Say you want to make a loaf with a specific recipe you've saved in percentages: 75% hydration, 2% salt, 18% starter. You decide you want to use 700g of flour. How much of everything else?

The formula flips:

So:

Done. One loaf figured out in about 30 seconds.

Now say you want four loaves at 1200g of flour each. Use 4800g as your flour weight and run the same formula. The percentages don't change. The math is identical. This is exactly how bakeries scale from a test batch to a full production run without anyone doing anything creative with the numbers.

For a deeper look at scaling, check out the guide on how to scale a sourdough recipe. It covers batch math in much more detail, including what to watch for when hydration needs adjusting at larger quantities.

Calculator

Run this in the calculator

scaling mode. Enter total flour weight and a saved percentage recipe, get grams for each ingredient computed automatically

Open calculator

The starter problem (and how to handle it)

Here's the thing nobody warns you about upfront.

Your starter is not just starter. Your starter is flour and water. Most casual recipes treat it as a single line item, and for everyday baking that's fine. But if you want honest math, especially around hydration, you need to account for what's hiding inside it.

Here's how it works.

A 100% hydration starter (the most common kind) is made with equal parts flour and water by weight. So 100g of starter contains 50g flour and 50g water.

Now go back to our worked example:

• 500g flour
• 375g water
• 10g salt
• 100g starter at 100% hydration

In most home recipes, that 500g is the flour you actually add from the bag, and the 100g starter contributes its own flour and water on top. So when you mix:

• 500g flour (added, the anchor for percentages)
• 375g water (added)
• 100g starter (which carries 50g flour and 50g water)
• 10g salt

The dough's total flour is 550g and its total water is 425g. The recipe's stated "75% hydration" is calculated against the anchor flour (375 ÷ 500), so it's a nominal number. The dough's true hydration is 425 ÷ 550, about 77%.

Worth knowing: a few professional formulas and books use the opposite convention, where the listed flour and water are the totals already and starter is broken out from inside them. Both approaches show up in print. This site, like most home baking, treats listed amounts as added.

Which means a 20% starter at 100% hydration is really:

• 10% prefermented flour sitting inside that starter
• 10% prefermented water sitting inside that starter

For a deeper look at how that prefermented flour and water moves your true hydration, see the sourdough hydration calculator guide.

Why does this matter? Two reasons.

First, comparing recipes. Two bakers can both say "20% starter" and mean slightly different things. One means 20% starter by weight relative to anchor flour. Another means 20% of the flour is prefermented (which would be a 40% starter at 100% hydration). Not always the same thing. Check the wording.

Second, scaling. If you ever switch starter hydrations (say, from a 100% to a stiff 50%) and don't account for the new flour/water split inside it, your true hydration shifts without you noticing.

Starter Builder

Build this in the starter tool

input starter weight and starter hydration percentage, get the flour and water components that live inside it

Open starter builder

For most home bakers making one or two loaves, treating starter as a single ingredient is totally fine. But the moment you start developing your own recipes or comparing formulas seriously, decomposing the starter is the move. The starter breakdown tool will do the split for you.

Standard ranges you'll see over and over

Once you start reading recipes in percentages, certain numbers will show up again and again. Here's a quick map of what's normal.

Salt almost always lands between 1.8% and 2.2%. Go below 1.5% and the bread tastes flat. Go above 2.5% and you'll notice it. Most sourdough recipes hit exactly 2%.

Hydration is where recipes diverge most. For sourdough specifically, you'll see everything from 65% (firm, easy to shape, great for beginners) up to 85% or even higher (very slack, open crumb, challenging to handle). If you're chasing that glossy, open crumb, the sourdough hydration calculator helps you dial in hydration based on your flour type and what you're going for.

Starter typically runs 10-25% for sourdough. Lower percentages mean slower fermentation and more complex flavor. Higher percentages speed things up, which is useful in cold kitchens. If you're working with commercial yeast instead, the percentages are much smaller (usually 0.1-1% for instant yeast) but the same logic applies. There's a guide on converting between yeast and sourdough if you need to swap leavens in a recipe.

Enriched breads (brioche, milk bread, soft rolls) introduce fat and sugar into the equation. Fat usually runs 10-30%, sugar 5-15%. These are percentages of flour weight, same as always.

Mistakes that bite beginners

A few things that catch people out early.

Forgetting the flour in the starter. Already covered above, but worth repeating. If you're scaling a formula or comparing recipes precisely, starter flour counts.

Scaling off total dough weight without the flour anchor. If you have a complete gram recipe, multiplying every ingredient by the same factor preserves the ratios cleanly. The trap is when you only know a target dough weight (say 800g) and try to back-solve. Then you have to find the flour weight first using the total formula percentage, then rebuild each ingredient from the percentages. Trying to eyeball it from total weight usually gives you wrong numbers.

Adding the percentages together and trying to interpret the sum. They don't add up to a meaningful number. 197% isn't hydration or anything else. It's just the sum of separate ratios. Leave it alone.

Mixing different flour types without adjusting hydration. If a recipe is written for bread flour and you swap in 20% whole wheat, you'll need more water. Whole wheat absorbs more liquid. The percentages don't change, but your total water percentage needs to go up a few points. This one takes experience to feel out, but knowing it exists puts you ahead.

Reading "20% starter" as if everyone means the same thing. Sometimes that means 20% starter by weight relative to flour. Sometimes the author is really talking about prefermented flour. Not always identical. Always check the recipe wording before you copy a number across.

Why every bakery uses this

It comes down to consistency.

A recipe written in baker's percentage works for one loaf and for two hundred loaves without a single change to the card. A new baker on the team can read it, pick a flour weight for their batch, and produce the same bread. Across days, across staff, across ovens, the ratios hold.

That's the real reason this system exists. Not because bakers love math. Because a percentage recipe never goes out of date and never needs to be rewritten for a different batch size. One card. Any size.

Once you start writing your own recipes this way, you'll see why. Tweak a loaf on Saturday, write down the percentages, and you've captured that recipe forever.

Baker's percentage feels opaque until it suddenly doesn't. The moment it clicks, you'll look back at the grams-only recipes you used to follow and feel a little sorry for past-you. It's just ratios. Flour is the anchor, everything else is relative to it, and the total will be more than 100% because that's how the math works.

That's all of it. Go bake something.