[Tex/LaTex] How to put line spacing with a certain length (kind of manually)

line-spacingspacing

I need to write a entire document with line spacing equals 1.5 cm. I've searched about it and found that there is three kinds of spacing: single, double and 1.5, but I need my document to be EXACTLY 1.5 cm (centimeters!). How do I do that? Is there some relation between "LaTeX spacing" and "centimeters"? I mean, for example,
A 1.5 spacing is approximatedly x cm (What is the value of x?)

Thanks everybody!

Best Answer

If this is LaTeX, try \setlength{\baselineskip}{1.5cm} anywhere after \begin{document}; if Plain or thereabouts, type \baselineskip=1.5cm directly.