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Hi all you amazing pros! I would like to make pattern #83850. It has 16 strands and 30 rows. How long should each strand be? Adult male wrist. Thank you!

Best guess is 100 -130 cm per string. It depends on how tight you knot, how long the bracelet needs to be, what closure you're making and what string you're using.
I always take 120-130 to be sure, no matter what (normal) pattern I'm making.

Hi!

Usually, the basic length I use, with six stranded embroidery floss, is 1.20m per string for an 18cm long bracelet, as I hate adding a new string.

We also have a tutorial on strings length just there: friendship-bracelets.net/tutorial.php?id=3683
And this answer on the FAQ is clear enough: https://www.friendship-bracelets.net/faq.php?id=2

I hope it helped you :)

Anyblia

Ok, great! That at least gives me an idea where to start. Thank you so much!