This free croissant butter block calculator sizes the butter sheet, called the beurrage, for laminated croissant dough. Enter your dough weight, the butter percentage and your fold plan, and the tool gives the butter weight, the square block size and the layer count, so every fold lands evenly.
Lamination lives or dies on the butter block. A block that is too small leaves bare dough that bakes flat, while a block that is too large squeezes out of the edges and melts away in the oven. The classic target is butter at about 25 percent of the dough weight, rolled to an even sheet that matches the dough size at each fold.
To use the tool, enter your numbers in the fields above and press the calculate button. The results table updates at once, and you can change any number and calculate again as often as you like. Everything runs in your browser, so nothing you enter is sent to a server, and you need no account and no sign-up.
The formula starts with butter weight, which is dough weight times the butter percent. Block size assumes butter density of 0.96 grams per cubic centimetre and an 8 millimetre sheet, so the sheet area is butter weight divided by 0.768, and the square side is the square root of that area. Each letter fold triples the layers, so three folds give 27 layers.
Example: for 1000 grams of dough at 25 percent butter with 3 letter folds, the tool gives a 250 gram butter block, an 18 centimetre square sheet at 8 millimetres thick, 27 layers, and 1250 grams of laminated dough. Roll the butter between baking paper to that square, chill it firm, and it will fold cleanly into the dough.
Tip: keep dough and butter at the same firmness. If the butter is much harder than the dough it cracks and tears through, and if it is much softer it melts into the dough and the layers vanish, so both should dent the same way under a finger.
Tip: chill between folds. A 30 minute rest in the fridge firms the butter again and relaxes the gluten, so the next roll-out stays even instead of shrinking back and squeezing butter out of the sides.
Tip: trim the edges before shaping. A thin, sealed edge bakes into a flat border, so a clean cut exposes the layers and lets the croissant puff tall and open in the oven.
Common question: How much butter do croissants need? About 25 percent of the dough weight is the standard starting point. Less butter gives fewer, drier layers, while much more butter makes handling harder and can leak in the oven.
Common question: What is a letter fold? It is folding the dough in thirds, like a letter going into an envelope. Each letter fold triples the layer count, so three folds turn one butter layer into 27 layers of dough and butter.
Common question: Why did my butter leak in the oven? The usual causes are butter that was too soft during folding, dough rolled too thin at the edges, or a proof that ran too warm. Keep everything cool and prove below 26 degrees.
Timing and storage matter as much as the numbers. Make the dough when you have time for a slow rise and a proper bake, not rushed between other jobs, because bread rewards patience far more than speed. Store finished bread in a way that protects the crust you worked for, and reheat gently rather than microwaving it soft.
A note on accuracy: weigh your ingredients with a kitchen scale, because cup measures vary by how flour is scooped and packed, and a 10 percent flour error changes hydration enough to notice. Check your scale with a known weight now and then, and keep the same units through the whole recipe so nothing gets converted twice by mistake.
This tool is free to use as often as you like. Bookmark it, run it for every batch, and let it carry the measuring while you focus on shaping, baking and enjoying the bread itself.