A good formula will have 30%-50% butter to flour ratio. This will help to determine how many layers are needed to create the flakiness in a croissant. The more butter, the more flavor but also the more delicate the structure of the layers as you do the turns needed to give you the right results. Am I getting to technical?
I hope that you are enjoying the info and can be a better baker by understanding the entire process of making the perfect croissant. You can do it at home even if I use professional equipment, I can help you to recreate what you need using what you have on hand.
The recipe is not that complicated and has relatively few ingredients. It is all technique in rolling, turning and forming these babies! Of course the rising, glazing and baking are crucial as well. There are tons of recipes using various amounts of butter. The one ingredient that I rarely see but have worked with is a croissant dough containing eggs. It is extremely important to not over mix the dough before adding the larger quantity of butter. Since you are rolling and folding the dough four times (the "turns"), you don't want to develop too much gluten at the beginning of the process or in the end your dough will be tough.
You may find some with more or less sugar and the butter can vary in quantity but NEVER EVER substitute margarine for butter unless you are vegan and eat such unholiness... so very sorry to my vegan friends, but I just find it a very bad substitute for butter... I don't know how I would live in a world without butter!! I could give up meat (if I really had to for health reasons) and wheat flour too but butter...oh I hate to even imagine...
Never count the butter lock-in as a turn on the dough it is merely placing the butter into the dough. Usually three letter folds are given with a 20 minute rest in between each one. A letter fold can be called a three fold or a single fold. Do not get confused these are all names for the same fold. It has three layers and is folded like you fold a letter into three parts. Once the dough is turned three times it can be wrapped and ideally it should be frozen and then thawed in the refrigerator the day before you form them and bake them. This will keep the dough very cold while you roll it out and then form them into pastries.
You can see how nicely these have risen. Puffy but not doubled in size only half again the size. Overproofing makes the dough bready and uninteresting.