When I first started making bracelets this weekend, just about every cobra weave tutorial I found said "basic rule of thumb is 1'-0" of cord per 1" of bracelet". I made all of one bracelet using this method, a seven incher, and used all of five feet, even though I should have used seven. Two feet of waste is no good!
Break out the calculator:

5' divided by 7" (5/7=.71)

This is a good starting point. I so want a little bit of waste so I can at least finish my piece, so I went ahead and rounded up to .75. That's your factor.
So when you need to make, for example, an 8" bracelet, multiply:

8x.75

That gives you 6'-0" of cord.
Using this factor, I've made a handful of bracelets since, and only end up with two small pieces of waste, averaging 2" in length, for each bracelet.

I'm not from America so what do these measurements mean?
Measurements given are using the Imperial system. Use the appropriate formula to convert to metric as needed.
<p>Very good idea. Thanks, I'm going to keep that in mind. Easy enough to remember that factor.</p><p>P.S. Don't feed the trolls!</p>