[Tex/LaTex] the equivalent of fullpage in geometry package

Question

There's an occasion when I am forced to use geometry package instead of fullpage. However the document margins should match another document which uses fullpage.

Where can I find the default top, bottom, right, left values when simply using fullpage?
The document class is article.

Answer 1

The only difference between

\documentclass[a4paper]{article}
\usepackage[
  margin=1.5cm,
  includefoot,
  footskip=30pt,
]{geometry}
\usepackage{layout}

\begin{document}
\layout
\end{document}

and

\documentclass[a4paper]{article}
\usepackage[cm]{fullpage}
\usepackage{layout}

\begin{document}
\layout
\end{document}

seems to be that the head height and the head separation in fullpage are zero.

For the in default option, change margin=1.5cm into margin=1in.

---

Just for experimenting, I compiled the same document with both preambles; the one with geometry with red text. I converted the DVI files to PNG with transparent background with dvipng. Next I superimposed the two PNG files in a single document. Here's the picture showing no essential difference between the two.