need to change the way title chapters are displayed in 'report' document class

Question

I'm using the report document class and the chapter titles are very large, in bold font, and left justified. I need them to be 18pt, not bold, and centered. I also need the words 'chapter 1' to be centered above the chapter title. My preamble and chapters look like this:

\documentclass[12pt]{report}
\usepackage{graphicx}
\usepackage{fullpage}
\usepackage{setspace}\doublespacing    % important!
\textfloatsep 0.75in                   % important with double spacing




\begin{document}

\chapter{chapter title}

\end{document}.

I have tried modifying as follows:

\centerline{\chapter{chapter title}}

or

\begin{center}
\chapter{chapter title}
\end{center}

but I don't think this is going to work...

Their are lots of posts related to this topic but I can't make sense of which exact parts to use for my application. Please help with my specific case.

Answer 1

You can achieve this by using titlesec package and \titleformat command:

\titleformat{\chapter}[display]{\Large\centering}{Chapter \thechapter:}{0pt}{}{}

where you choose what command to modify (\chapter), use vertical mode with zero spacing (display and 0pt) and set font and centering (\Large is a 18 pt?).

Full listing:

\documentclass[12pt]{report}
\usepackage{graphicx}
\usepackage{fullpage}
\usepackage{setspace}
    \doublespacing
    \textfloatsep 0.75in

\usepackage{titlesec}
    \titleformat{\chapter}[display]{\Large\centering}{Chapter \thechapter:}{0pt}{}{}

\begin{document}

    \chapter{chapter title}

\end{document}