@giulimar for bracelets, it’s usually recommended to use your wingspan length of string (from one hand to the other, stretching across your torso) and because of all the folding and knots, it shortens down to fit your wrist
@whosjanvii cut two strings of 130cm from each color. But cut 150cm from the string that you want to make a loop. Then fold them into two and put all ends at the same line except that one you want to make the loop will be a little longer than others. But when you finish the loop all should be equal length. Then you can start tying as in the pattern. Hope this helps.