General ⇒ Setting leading...are my assumptions right or wrong?

[Noraft]

I'd like to typeset a book in Palatino 10, with 12 point leading. Normally, my only default options are single, 1.5, and double spacing.

I know that I can set \linespread{factor} to {1.3} (1.5 spacing) or {1.6} (double spacing). However, if 1.3 = space and a half and 1.6 = double spacing, does that mean that I can assume .1 is a sixth of a line? So if I'm using Palatino 10, a factor of .1 is 1.67 points? if so, I could approximate 10/12 leading with \linespread{1.12}

Is this correct? Or am I starting with a faulty assumption?

[phi]

Do you really want 12 pt leading? This would be very much. Or do you rather want 12 pt as baseline skip (distance between consecutive baselines)? This is already the default. I think that you cannot set the leading directly, as it depends on the properties of the selected font. For example, if you have a horizontal box (line), then the leading would be the baseline skip minus the height minus the depth of the box. \linespread multiplies the baseline skip by the argument number, so 12 pt × 1.3 = 15.6 pt ≈ 15 = 1.5 × 10 pt and 12 pt × 1.6 = 19.2 pt ≈ 20 = 2.0 × 10 pt.