Equivalent of one and half line spacing in terms pt

I have the following decleration:

``````\documentclass[12pt,a4paper,oneside,noindent,nocenter,bold]{thesis}
``````

The required format for captions of figures is that there should be a skip equal to 1.5 line. So, I do the following to get the required effect:

``````\usepackage[skip=18pt]{caption}
``````

What I assume here is that `12pt x 1.5 = 18pt`, which I am not sure of its validity. Therefore:

1. How do we calculate equivalent of 1.5 line spacing in terms pt? If I want to make a line 1.5 of the a selected font manually, how should I calculate it?

2. Is there any way to assign value to skip dynamically? I mean instead of using `skip=18pt` (or any constant), can I use something like `skip=onehalfspacing` with or without using other packages?

• Welcome to TeX.SE. There are a lot of document classes named `thesis` available on the Internet. Please provide a link to the one you're using. – Mico May 27 '15 at 7:54
• Welcome to TeX SX! If you look at the documented code of `setspace`, one half spacing corresponds to a factor of 1.241 in 12pt. But as the `skip`in the `caption` package is the distance between caption and figure/table, they simply mean `skip=1.5\baselineskip`. In points that would be \$\approx\$ 22.5pt, but it's better to use the expression in `\baselineskip`. – Bernard May 27 '15 at 8:01
• @Mico I use standart thesis class that comes with MiKTeX – Mehmed May 27 '15 at 8:19
• @Bernard Thank you for the solution and the explanations, could you also write it as an answer so that I can accept it. – Mehmed May 27 '15 at 8:21
• @Mehmed: Done. I've checked and corrected some details. – Bernard May 27 '15 at 8:43

If you look at the documented code of setspace, one half spacing corresponds to a factor of `1.241` in 12pt, `1.25` for 10 and 11pt. But as the `\skip` in the `caption` package denotes the distance between caption and figure/table, I think they simply mean `\skip=1.5\baselineskip`. In points that would be approximately 1.5×14=21.75pt, but it's better to use the expression in \baselineskip as it gives some elasticity.