There are those of us who use cups and those of us who use LB’s and Oz’s, or grams. I know that a large hand grab of flour out of the packet is about 55g and that a large pinch of instant yeast, for me, is about 1/8th of a teaspoon or 0.5grams. And, that a thumb and two fingers pinch of loose tea makes an excellent mug of tea. Another baker here can eyeball teaspoons and desert spoons in the palm of her hand.

That takes years of practice and it's not such a helpful way to write a recipe for others to follow.

Accuracy matters in bread making. It is the only way to get reliably predictable results. May I add my voice to the loud chorus saying, “Please consider giving up cups?" They’re just too inaccurate and a good set of electronic scales is quite inexpensive.

I have spent a lifetime converting the recipes I come across to my preferred measures.

Baker’s percent deals with all of our ingredient measures in a very flexible manner and no need for conversions.

How to do the maths

Essentially, we take all of the flour in the recipe, including the flour in scalds, preferments and natural leavens and that is 100%. All other ingredient are given as a percentage of that 100% as a weight.

So if I have 2lb (32oz) of flour and my recipe calls for 22oz of water that’s: 22oz divided by 32oz which is 0.69. We multiply that by 100 to make that into %.

22/32 x 100 = 69%. We are using 100% of flour and 69% of water.

To get that back into imperial measures we merely multiply the weight of the flour in ounces, with the percentage of the ingredient.

69 divided by 100 makes is a fraction again, times the weight of the flour we are using, gives us our weight.

69/100 = 32oz x 0.69 = 22oz of water.

It works just as well in grams.

907g (flour) x 0.69 = 626g

A simple way to work with percentages.

To get 70% of 500g of flour we multiply 500 by 0.7

We have moved the decimal point two places to the left. This converts any percentage figure to a fraction of 100 for multiplication.

Why use Baker's Percent?

Having our recipes written in this form enables us to do a number of things, very easily.

No more converting between Imperial and Metric measures

That water is 67% of the total weight of your flour, in whatever weight scale you prefer, metric or imperial. No conversions required. All bakers whatever the measure they prefer can read the recipe without needing to convert the meadures.

Ingredient Windows

Every ingredient has a window in which it works well. For example, adding water to flour at under 55% does not give enough water to properly hydrate the flour. More than 65% of water is unlikely to work with weak flour such as heirloom or ancient grain and more than 75% of water with a strong bread flour needs to have a very good reason, such as for ciabatta.

Vegetable oil has a window of 2% - 25%. Vegetable oil in a dough reduces the glutens ability to trap CO2 and so it can deny us a light loaf. It has a ‘sweet spot’ of about 3% where it helps in slowing staling and gives a softer mouthfeel and still doesn’t have too much impact on the final loaf volume.

Above 15% vegetable oil starts to have a marked impact on the volume of the final loaf. This is really a high maximum for a loaf bread. However, for pizzas, focaccias and other flat breads where the gluten does not have to support a large mass of dough above, we can ramp it up to 25% for the mouthfeel and with olive oil, the flavour.

Instant yeast’s recommended dosage for 500g of flour is a level teaspoon, 3.15g, or 0.0063%. This gives a brisk dough fermentation time whilst allowing some time for flavours to develop. We can increase this to 1% if we need a super fast ‘bread on the table’, or we can go down to 1/8 of that for a yeasted preferment which will need to be left for eight hours or overnight to ferment in those flavours for our bake.

Every ingredient has it’s window. Working in Baker's percent enables us to instantly see whether the recipe is workable. Those Typo's that frequently creep in during publishing immediately stand out too.

Varying recipes

If we know the window in which an ingredient works at its best we can use that information to vary a recipe without getting a baking fail. We want to increase the speed of the fermentation and so decide to add diastatic malt. The amylase in it will make sugars for the yeast to feed on more readily. It will also add some malty tones to the finished loaf.

If too much Diastaic malt is added the increased amylase will destroy a loaf's crumb structure. The same will happen if a long cold fermentation is used, such as in retarding the dough. The 'ideal window for Diastatic Malt is 0.5% – 0.6%. Knowing this we can add it to a recipe with some confidence.

Checking Recipes for errors

Once we get used to Baker’s Percents it becomes a very quick task to check a recipe. Recipes online and in books are notorious for errors.

Here in the UK we have a very famous Cake Baking Chef. Who heads up a major TV show. He is excellent and has incredible knowledge. He published a Bread Baking Book. Not only were the recipes in the style of early 1960’s small kitchen baking (think buying a 1960’s car in the 21st Century – things have moved on), but it was rife with errors. Many recipes were unusable without correction. Buckets of yeast here and buckets of salt there. At times the hydration levels varied well out of anything sensible too. Being kind, I expect it was ghost written and not checked before printing. The point is that by converting his recipes to baker’s percent all of the errors were immediately obvious. 15 grams of salt is hard to spot as an error in a recipe. But, converted to Baker’s percent it became 3%. Salt has a window of about 1.2% - 2%. 3% would have been very salty indeed.

Scaling Recipes

Another advantage of Baker’s Percent is the ease of scaling. If I want two 2lb loaves I know I need to use 1kg of flour. About 2.2lb’s. It's then very easy to multiply that by the percentages in the recipe.

Tip: I dislike devices like echo dot. However, someone gave me one and I had no idea what to use it for. Then one day I discovered it would do all of my bread maths for me. When reading recipes I merely have to call out, “echo, what’s 65% of 500” or, “echo, what’s 400 Fahrenheit in Centigrade.” It works a treat!

Charlie Chain Baker has a great video on how to work in Bakers Percent.