Baking Maths – The Baker’s Percentage

I’ve written posts in the past about the ingredients used in creating new bread recipes, and about the standard skills that I apply to each of my loaves. There is, however, a step before all of this that needs some attention: planning.

recipe notes
Working out a new recipe on paper, before the trial and error of baking

When I started baking a few years ago, I relied on fairly simplistic recipes with reliable outcomes. I began with recipes like Jamie Oliver’s foccacia, which produced a good result every time. As my own baking skills developed, the recipes I used became more complicated, leading to sourdoughs and enriched, sweet breads.

Along the way I came across a book that I have mentioned on here before: Peter Reinhart’s The Bread Baker’s Apprentice, and one part in particular has changed the way I plan and bake bread: The baker’s percentage.

The Baker’s Percentage

The purpose of a baking formula is to place all of the ingredients in relation to the flour used in the recipe. The reason for this is that, with a few simple calculations, it is possible to work out not only how much of each ingredient to use, but also to predict the outcome of the bread. As Reinhart himself writes,

“possession of this knowledge will strengthen your ability to control the outcome of your baking.” (p. 40).

So, how does it work? The total flour weight, or TFW, is always represented as 100%. From this, the other values are calculated. Using my most recent recipe, for beetroot sourdough, this would mean that 1000g of all purpose flour + 200g rye flour from the starter would equal 100% in the formula.

  • 1kg all-purpose (plain) flour
  • 670g water
  • 400g rye starter @ 100% hydration (200g starter + 200g water)
  • 18g salt
  • 430g raw beetroot, coarsely grated

From this, the rest of the ingredients can be converted by dividing the ingredient weights (I) by the total flour weight (TFW), and multiplying by 100. So, for the water: (I/TFW)x100 = ((670+200) / 1200)x100 = 72.5%.

The beetroot sourdoughs – 67% hydration with 40% starter

As a start, this not only gives the amount of water, but also the hydration of the final dough. Applying this to the rest of the ingredients gives the following:

Total Flour (including flour from starter): 100%
Total Water (including water from starter): 72.5%
Salt: 1.5%
Beetroot: 35.8%

Some other aspects of this bread can now be worked out from the formula. 72.5% hydration is fairly high, but still not as high as, for example, a ciabatta. This dough will probably be fairly wet, but will hold its shape. The high amount of starter means that the total bulk ferment and proof time will be relatively short for a sourdough, and unless the dough is refrigerated, it will need to be made and baked on the same day or it will overproof. The amount of salt (1.5%) is appropriate, as most breads will have between 1.5 and 2%.

A knowledge of this basic formula has many applications. If you find a recipe you like, but feel that it is perhaps a little dense, then you can increase the hydration and experiment. Similarly, if you wish to manage the proofing time, you can alter the percentage of starter or yeast. If a bread is too bland, you can safely increase the amount of salt, but without going much beyond that 2% guideline.

These ciabatta have a very high hydration, meaning that the very
These ciabatta have a very high hydration, meaning that the very “slack” dough can be difficult to shape

I have actually slightly changed this post following a discussion on The Fresh Loaf. Originally, I was following Reinhart’s advice and treating the starter as an ‘ingredient’. However, I have been convinced that breaking it down into the flour and water, and adding those to make the total flour weight, is a far better approach. The slightly more complex approach gives a more accurate result: treating the starter as a 400g ingredient gives a hydration of 67% (670g of water to 1000g flour). Breaking it down gives 72.5% (870g water to 1200g flour). There is quite a difference between 67 and 72% hydration, so from now on I’ll be using the latter approach.

I will be following up on this post with further ones down the track, writing about how to use the baker’s percentage to scale up or down the number of loaves, to change the size of loaves, and to “troubleshoot” recipes. The topic itself can get very confusing – my advice as a homebaker would be to find something that works, and leave the fine-tuning to the professionals!

dmsnyder at The Fresh Loaf has an excellent post on Baker’s Percentages here.

If you wish to learn more about baker’s percentages, I would highly recommend getting a hold of The Bread Baker’s Apprentice.

This loaf is around 70% hydration - not quite as wet as a ciabatta, but dry enough to hold shape as a
This loaf is around 70% hydration – not quite as wet as a ciabatta, but dry enough to hold shape as a “boule”

Skills series

A while back I put together a few blogs on baking skills, using the knowledge I have gained over the last four or five years through trial, error, and a lot of great recipe books. As I haven’t posted in a while (because I haven’t baked in a while- busy weekends) I thought I’d pull together those skills posts into one page, so, here they are!

#1 Autolyse
#2 Kneading
#3 Bulk Ferment
#4 Divide and Shape

And because I won’t be baking this weekend, here’s an old pic of some millet sourdough to be getting along with…


Overnight 100% Rye Sourdough

This bread was made using a combination of Dan Lepard’s recipe for 100% Sour Rye, and methods from Ken Forkish and Peter Reinhart.

The temperature is still up, and the best time to bake is early in the morning. Early morning baking calls for a bit of a manipulation of the proofing time of bread, and so overnight retarding in the fridge is ideal. Since it is hot in the kitchen by the afternoon, it is also a bonus to have a recipe that does not call for much hard work, and this no-knead rye bread from Dan Lepard is the perfect loaf for the situation.

Despite originating in colder climates – Scandinavia, Russia, Eastern Europe for example – a rye flour sourdough works well here because it does not need a great deal of handling and only requires a single proof; no bulk fermentation is needed. This is partly because the gluten in rye flour is extremely weak, and does not benefit from the extra developing time. Also, rye flour, when mixed with water, becomes extremely sticky. Kneading only exacerbates the problem, quickly turning the dough into an unworkable mess.

The cracks along the bottom are from the loaf’s expansion whilst proofing; rye flour is much less elastic than wheat flour.

Another bonus of this recipe was the opportunity to try something I had never used before – a rye scald. Lepard’s “hot gelatinous rye mix” is 4 parts boiling water to 1 part rye flour, which is mixed an hour prior to beginning the bread and used both in the dough and as a wash before the bread goes into the oven. The scalded rye mix adds an elasticity to the loaf which would otherwise be absent.

The recipe is from Dan Lepard’s The Handmade Loaf and I highly recommend buying it if you’re into a little bit of experimentation with traditional loaves. For the ingredients to this bread, go and buy a copy!

For the method, I followed my own instructions to suit the overnight retardation. It is a mix of Ken Forkish’s method for an overnight sourdough from Flour Water Salt Yeast, and a few techniques I picked up from Peter Reinhart’s The Bread Baker’s Apprentice.

The sliced loaf – the crumb is slightly more open than in a regular rye bread, due to the inclusion of the scalded rye mix


  1. 8pm, 2 days before baking: Refresh 2 tbsp rye starter with 100g rye flour and 150g lukewarm water.
  2. 9am, 1 day before baking: Refresh starter with 100g rye flour and 150g lukewarm water.
  3. 3pm, 1 day before baking: Mix boiling water and rye flour, stand.
  4. 4pm, 1 day before baking: Combine remaining ingredients, reserving 1 tbsp of the rye mix for glazing. Shape the dough as per instructions in the recipe and place into a floured banneton.
  5. Proof for 4 hours.
  6. 8pm, 1 day before baking: Place banneton into a clean plastic bag and refrigerate overnight.
  7. 6:30am, day of baking: Preheat oven to 210°C
  8. 7:10am, day of baking: Bake at 210°C for 50 minutes.
  9. Cool on a wire rack, then wrap in baking paper and store for one day before eating.
    The finished rye loaf. The rye flour gives an amazing colour, texture, and flavour to the sourdough.