@hinamyyy for me 99 rows would be around 16cm, so for the base strings you need 16cm plus whatever you need for the ties/loop. If you have ever made an alpha you can also use your own measurements to estimate how long 99 rows are. If you want to shorten the bracelet to fit your wrist, you'll need enough base string to reach around your wrist and then again some extra for loop and ties. For the leading strings I recommend just leaving them on the skein and cutting them in the end.