Weigh everything. Write it down. Bake it again.

Flour is always 100%

In baker's percentages every ingredient is written as a share of the total flour weight. Water at 65% means 65 g of water for every 100 g of flour; salt at 2% means 2 g. Write a recipe this way and three useful things happen. You can scale it to any size by multiplying. You can compare two recipes at a glance: a 65% dough bakes into a tight sandwich crumb, an 80% dough into an open, wet ciabatta. And you can catch mistakes before you mix, because a cookie with 20% butter is not a cookie.

To convert a recipe you already use, weigh the flour, then divide each ingredient by that weight and multiply by 100. If a recipe uses two flours, they add up to 100% together. Typical anchors for lean bread: salt 1.8–2.2%, instant yeast 0.7–1.2% for a same-day loaf, water 60–75%.

Percentages only work by weight. A cup of flour weighs anywhere from 120 g to 150 g depending on how it was scooped, which is a 25% swing before you have started. A scale reading in 1 g steps is the most useful tool in the kitchen; a 0.1 g pocket scale for salt and yeast is a cheap second.

Flour

Protein is what you are buying. Bread flour (12–14%) makes elastic dough that holds gas; plain or all-purpose (10–12%) suits soda bread, cookies and most cakes; cake flour (7–9%) gives a fine, tender crumb. Wholemeal absorbs more water, so add 5–10% extra and expect a denser loaf. Keep white flour in an airtight tub; wholemeal contains the oily germ and turns rancid within months, so keep it cold.

Leaveners

Instant yeast goes straight into the flour. Active dry yeast is coarser and needs dissolving in the liquid first; use about 25% more by weight. Bicarbonate of soda only works with an acid in the bowl (buttermilk, yoghurt, brown sugar, natural cocoa); baking powder carries its own acid. Test old boxes: bicarb should fizz in vinegar, baking powder in hot water.

Fats, sugar, salt

Butter is about 80–82% fat and the rest water, which is why melted butter behaves differently from oil. Brown sugar carries molasses, adding moisture and a little acidity. Fine salt is what the recipes assume; flaky salt is half as dense by the spoon, so always weigh it.

Weighing

Put the bowl on the scale, zero it, add the first ingredient, zero again, and continue. One bowl, no measuring cups, nothing to wash. For yeast doughs, use water around 25–30 °C; hotter water speeds fermentation but flattens flavour.

Your oven is lying

Home ovens are commonly 10–25 °C off their dial and swing during a bake. A cheap oven thermometer on the middle shelf settles the argument. Preheat for at least 20 minutes, bake on the middle shelf, and rotate the tray two-thirds of the way through. For fan ovens, drop the temperature by about 20 °C.

Knowing when it is done

A probe thermometer removes the guesswork: lean bread is done at 93–98 °C inside, enriched bread at 88–93 °C. Cookies should look slightly underdone in the centre when they come out; they finish on the hot tray. Let bread cool at least an hour before slicing, because the crumb is still setting.

Keep notes

Date, flour brand, room temperature, timings and what you would change. After three bakes of the same recipe your notes are worth more than any book.