dsad67, Вот что написано в примечании к калькулятору
I checked your values against the ones given by [insert famous string maker], and they're different. Why?
We don't know. Makers who offer tension charts seldom state the scale length, of course, but even with a lot of experimentation we've found that our figures typically differ by 5--10% from the quoted figures. For what it's worth, we're using a classic formula and pretty good data.