LaTeX Lengths and Units

\documentclass{article}
\usepackage[margin=1in]{geometry}

\begin{document}

% Setting margins
\newgeometry{left=2cm, right=2cm, top=3cm, bottom=3cm}

% Horizontal spacing
This text\hspace{2cm}has 2cm space.

% Vertical spacing
This is the first line.
\vspace{1in}
This line is 1 inch below.

% Paragraph indentation
\setlength{\parindent}{0.5in}
This paragraph is indented by half an inch.

% Line spacing
\setlength{\baselineskip}{14pt}
This text has 14pt baseline skip.

\end{document}

\documentclass{article}
\begin{document}

% Get current values
The current font size is \the\fontdimen6\font pt.

% Text width measurements
Text width: \the\textwidth

Line height: \the\baselineskip

Paragraph indent: \the\parindent

% Using lengths in calculations
\newlength{\mywidth}
\setlength{\mywidth}{0.5\textwidth}
This box is half text width: \fbox{\parbox{\mywidth}{Content here}}

\end{document}

\documentclass{article}
\usepackage{geometry}

% Absolute measurements
\geometry{
    paperwidth=210mm,      % A4 width
    paperheight=297mm,     % A4 height
    left=25mm,             % Left margin
    right=25mm,            % Right margin
    top=30mm,              % Top margin
    bottom=30mm            % Bottom margin
}

% Relative to paper size
\geometry{
    width=0.8\paperwidth,  % 80% of paper width
    height=0.9\paperheight % 90% of paper height
}

\begin{document}

Current page dimensions:
\begin{itemize}
\item Paper width: \the\paperwidth
\item Paper height: \the\paperheight
\item Text width: \the\textwidth
\item Text height: \the\textheight
\end{itemize}

\end{document}

\documentclass{article}
\begin{document}

% Em-based spacing (scales with font size)
{\normalsize Normal text with \hspace{2em} 2em space.}

{\large Large text with \hspace{2em} 2em space.}

{\huge Huge text with \hspace{2em} 2em space.}

% Ex-based spacing (scales with x-height)
Baseline text\vspace{2ex}
Text with 2ex vertical space above.

% Comparison of units
\begin{tabular}{ll}
2cm space: & Text\hspace{2cm}continues \\
2em space: & Text\hspace{2em}continues \\
2ex space: & Text\hspace{2ex}continues \\
\end{tabular}

\end{document}

\documentclass{article}
\usepackage{calc}

\begin{document}

% Define custom lengths
\newlength{\sidebarwidth}
\newlength{\mainwidth}

% Calculate widths
\setlength{\sidebarwidth}{0.25\textwidth}
\setlength{\mainwidth}{\textwidth - \sidebarwidth - 1cm}

% Use in layout
\noindent
\begin{minipage}{\sidebarwidth}
\textbf{Sidebar}\\
Content here
\end{minipage}%
\hspace{1cm}%
\begin{minipage}{\mainwidth}
\textbf{Main Content}\\
This is the main content area calculated to fit properly.
\end{minipage}

% Complex calculations
\newlength{\complexwidth}
\setlength{\complexwidth}{(\textwidth - 3\columnsep) / 2}

Width calculation: \the\complexwidth

\end{document}

\documentclass{article}
\usepackage{ifthen}

\begin{document}

% Set length based on conditions
\newlength{\dynamicspace}

\ifthenelse{\lengthtest{\textwidth > 400pt}}
  {\setlength{\dynamicspace}{2cm}}
  {\setlength{\dynamicspace}{1cm}}

Dynamic spacing: \the\dynamicspace

% Responsive margins
\newcommand{\responsivemargin}{%
  \ifthenelse{\lengthtest{\textwidth > 500pt}}
    {2cm}
    {1cm}
}

\newgeometry{margin=\responsivemargin}

\end{document}

\documentclass{article}
\begin{document}

% Fixed horizontal spaces
Word\hspace{1cm}space

% Flexible spaces
Left\hfill Right

% Negative space
Over\hspace{-2mm}lap

% Stretchable space
\hspace{1cm plus 1cm minus 0.5cm}

% Fill remaining space
Text\hfill\hfill More text

% Specific spacing commands
Thin\,space (3/18 em)
Medium\:space (4/18 em)
Thick\;space (5/18 em)
Quad\quad space (1 em)
Double\qquad space (2 em)

\end{document}

\documentclass{article}
\begin{document}

First paragraph.

\vspace{2cm}
Paragraph with 2cm space above.

\vspace*{1in}
Paragraph with 1 inch space that won't disappear at page breaks.

% Stretchable vertical space
\vspace{1cm plus 2cm minus 0.5cm}
Flexible space above this paragraph.

% Fill remaining page
Content at top.
\vfill
Content at bottom.

% Negative vertical space
Line one.
\vspace{-\baselineskip}
Line that overlaps above.

\end{document}

\documentclass{article}

% Customize default lengths
\setlength{\parindent}{2em}        % Paragraph indentation
\setlength{\parskip}{1ex plus 0.5ex} % Space between paragraphs
\setlength{\baselineskip}{14pt}    % Line spacing
\setlength{\columnsep}{2em}        % Column separation

% Custom length variables
\newlength{\sectionspace}
\setlength{\sectionspace}{2ex plus 1ex minus 0.5ex}

\newlength{\figuremargin}
\setlength{\figuremargin}{1cm}

\begin{document}

% Use custom lengths
\section{Introduction}
\vspace{\sectionspace}

Normal paragraph with custom settings.

% Dynamic adjustments
\addtolength{\leftskip}{2em}
This paragraph is indented by 2em on the left.
\addtolength{\leftskip}{-2em}

Back to normal margins.

\end{document}

\documentclass{article}

% Custom spacing commands
\newcommand{\smallgap}{\vspace{0.5\baselineskip}}
\newcommand{\mediumgap}{\vspace{\baselineskip}}
\newcommand{\largegap}{\vspace{2\baselineskip}}

% Responsive spacing
\newcommand{\smartspace}[1]{%
  \ifthenelse{\lengthtest{#1 > 2cm}}
    {\vspace{#1}}
    {\vspace{2cm}}%
}

% Context-aware spacing
\newcommand{\sectiongap}{%
  \ifthenelse{\equal{\@currsize}{\large}}
    {\vspace{1.5ex}}
    {\vspace{1ex}}%
}

\begin{document}

First section.
\smallgap

Second section.
\mediumgap

Third section.
\largegap

Fourth section with large gap.

\end{document}

\documentclass{article}
\usepackage{amsmath}

\begin{document}

% Math mode spacing units
\begin{align}
f(x) &= x^2 \quad \text{(1 em space)} \\
g(x) &= x^3 \qquad \text{(2 em space)} \\
h(x) &= x^4 \, \text{(thin space)} \\
i(x) &= x^5 \: \text{(medium space)} \\
j(x) &= x^6 \; \text{(thick space)} \\
k(x) &= x^7 \! \text{(negative thin space)}
\end{align}

% Custom math spacing
\begin{equation}
\int_0^\infty \! f(x) \, dx = \sum_{n=0}^\infty \, a_n
\end{equation}

% Math spacing commands
\[
\text{Thin: } a\,b \quad
\text{Medium: } a\:b \quad  
\text{Thick: } a\;b \quad
\text{Quad: } a\quad b
\]

\end{document}

\documentclass{article}
\usepackage{graphicx}
\usepackage{booktabs}

\begin{document}

% Table with unit-based sizing
\begin{table}[h]
\centering
\begin{tabular}{p{3cm}p{4cm}p{2cm}}
\toprule
Fixed 3cm & Fixed 4cm & Fixed 2cm \\
\midrule
Content adapts & to specified & column width \\
\bottomrule
\end{tabular}
\caption{Table with fixed column widths}
\end{table}

% Figure scaling with units
\begin{figure}[h]
\centering
% Scale by absolute size
\includegraphics[width=8cm]{example-image}
\caption{Figure scaled to 8cm width}
\end{figure}

% Relative scaling
\begin{figure}[h]
\centering
\includegraphics[width=0.8\textwidth]{example-image}
\caption{Figure scaled to 80\% of text width}
\end{figure}

\end{document}

\documentclass{article}
\usepackage{framed}

% Define environment with custom spacing
\newenvironment{myquote}[1][2em]
{%
  \vspace{1ex}%
  \begin{quote}%
  \leftskip=#1%
  \rightskip=#1%
  \itshape%
}
{%
  \end{quote}%
  \vspace{1ex}%
}

\begin{document}

Regular paragraph text.

\begin{myquote}
This is a quote with default 2em indentation.
\end{myquote}

\begin{myquote}[4em]
This quote has 4em indentation on both sides.
\end{myquote}

Regular text continues.

\end{document}

\documentclass{article}

% Good: Font-relative spacing
\setlength{\parskip}{0.5\baselineskip plus 0.2\baselineskip}

% Good: Consistent unit system
\geometry{margin=2.5cm, marginparwidth=2cm}

% Good: Flexible spacing
\newcommand{\flexspace}{\vspace{1ex plus 0.5ex minus 0.2ex}}

% Avoid: Mixing systems inconsistently
% \geometry{margin=1in, marginparwidth=3cm}  % Don't mix

% Good: Relative to context
\newlength{\myindent}
\setlength{\myindent}{2em}  % Scales with font

\begin{document}

Properly spaced content with consistent units.

\end{document}

\documentclass{article}
\usepackage{layouts}

\begin{document}

% Display current settings
\begin{itemize}
\item Text width: \the\textwidth
\item Text height: \the\textheight
\item Line height: \the\baselineskip
\item Paragraph indent: \the\parindent
\item Paragraph skip: \the\parskip
\end{itemize}

% Show page layout
\currentpage
\pagediagram

% Measure specific elements
\newlength{\testlength}
\settowidth{\testlength}{Sample text to measure}
Width of "Sample text to measure": \the\testlength

\settoheight{\testlength}{Sample text}
Height of "Sample text": \the\testlength

\end{document}