Right align header not working

Question

I'm trying to align my header to the right side but it is not going all the way to the right.

Here is a minimal example (I'm including my margins in case that is part of the problem? I honestly have no idea):

\documentclass[11pt]{article}

\usepackage{blindtext}
\usepackage{nopageno}
\usepackage{fancyhdr}

\pagestyle{fancy}
\fancyhf{}
\rhead{header}
\renewcommand{\headrulewidth}{0pt}

\textwidth=7in
\textheight=9.5in
\topmargin = -.25 in
\hoffset=-1in
\voffset=-0.5in
\parskip = 0.1in
\parindent = 0.0in

\begin{document}

\blindtext

\end{document}

Answer 1

You should set \pagestyle{fancy} after having set the page parameters, because fancyhdr uses the current text width for preparing its headers and footers.

I recommend using geometry, though: probably

\usepackage[textwidth=7in,textheight=9.5in]{geometry}
\usepackage{fancyhdr}

\pagestyle{fancy}
\fancyhf{}
\fancyhead[R]{header}
\renewcommand{\headrulewidth}{0pt}

is sufficient for your needs.

Above all, never set \hoffset and \voffset: they are thought for making corrections in case the output driver needs them.

Answer 2

This often happens (at least on my side) when you set a different page geometry for the title page.

If, you set pagestyle{fancy} and all the header specifications already in the preamble, then the your header specification are for the default geometry. If you change your page geometry afterwards, all the header settings will be skewed. Therefore, I recommend a specifing in a newcommand and calling it when your page properties are set and done.