You can enter your string length in any unit of measurement and the results will be displayed in that unit.
*The tastino is an auxiliary fret before the first fret of the 4th course. A short piece of fret material or wood can be taped or glued there.
The data used here comes from the spreadsheet fret calculator by Daniel F. Heiman and the Lute Society of America (2006), which is based on historical sources and also provides some more temperaments. I have used it for a long time, but I felt it might be useful to have a web app for this too.
For more information about meantone temperament on the lute, please see David van Ooijen's article, which is a very thorough explanation.