A LaTeX compiler (also called an engine) transforms your .tex source files into the final output format (usually PDF). Understanding the differences between compilers helps you choose the right tool for your project.
In LaTeX Cloud Studio: We handle compiler selection automatically, but you can switch between engines in your document settings for specific needs.

​
What is a LaTeX Compiler?

A LaTeX compiler:
  1. Reads your source file (.tex)
  2. Processes all commands and content
  3. Generates output (PDF, DVI, etc.)
  4. Reports any errors or warnings
Think of it as a translator that converts your human-readable LaTeX code into a beautifully formatted document.

​
Main LaTeX Compilers

​
pdfLaTeX (Default Choice)

The most common and widely-supported compiler. Pros:
  • Fast compilation
  • Excellent compatibility
  • Mature and stable
  • Supports most packages
  • Default in most systems
Cons:
  • Limited to 8-bit fonts
  • No direct Unicode support
  • Can’t use system fonts
Best for:
  • Most documents
  • Academic papers
  • When compatibility matters
  • Beginning LaTeX users
\documentclass{article}
\usepackage[utf8]{inputenc} % Needed for special characters
\usepackage[T1]{fontenc}     % Better font encoding

\begin{document}
This document compiles perfectly with pdfLaTeX!
\end{document}

​
XeLaTeX (Modern Typography)

A modern engine with excellent font support. Pros:
  • Full Unicode support
  • Use any system font
  • Better multilingual support
  • Advanced typography features
  • Handles complex scripts
Cons:
  • Slower compilation
  • Some packages incompatible
  • Larger file sizes
Best for:
  • Documents with special fonts
  • Multilingual documents
  • Non-Latin scripts
  • Typography-focused work
\documentclass{article}
\usepackage{fontspec} % XeLaTeX font selection

% Use any font installed on your system
\setmainfont{Helvetica Neue}
\setsansfont{Arial}
\setmonofont{Consolas}

\begin{document}
XeLaTeX lets you use any font: English, 中文, العربية, ελληνικά!
\end{document}

​
LuaLaTeX (Programmable Power)

The newest engine with embedded Lua scripting. Pros:
  • Full Unicode support
  • Lua scripting capability
  • Modern font handling
  • Microtype improvements
  • Active development
Cons:
  • Slowest compilation
  • Newest (less documentation)
  • Some compatibility issues
Best for:
  • Complex programmatic documents
  • Advanced typography
  • When you need scripting
  • Future-proof projects
\documentclass{article}
\usepackage{fontspec}
\usepackage{luacode}

\begin{document}
LuaLaTeX can execute Lua code:

\begin{luacode}
for i = 1, 5 do
    tex.print("Line " .. i .. "\\\\")
end
\end{luacode}
\end{document}

​
Comparison Table

FeaturepdfLaTeXXeLaTeXLuaLaTeX
SpeedFast ⚡⚡⚡Medium ⚡⚡Slow ⚡
UnicodeLimitedFull ✓Full ✓
System FontsNo ✗Yes ✓Yes ✓
CompatibilityExcellentGoodGood
ScriptingNoNoLua ✓
Memory UsageLowMediumHigh
Output QualityExcellentExcellentExcellent

​
How to Choose

​
Use pdfLaTeX when:

  • You’re just starting with LaTeX
  • Writing standard academic documents
  • Need maximum compatibility
  • Want fastest compilation
  • Using traditional LaTeX packages

​
Use XeLaTeX when:

  • Need specific fonts (corporate branding)
  • Writing in multiple languages
  • Using non-Latin scripts
  • Want OpenType font features
  • Typography is crucial

​
Use LuaLaTeX when:

  • Need programmatic document generation
  • Want the latest features
  • Require advanced typography
  • Can accept slower compilation
  • Building complex automated documents

​
Compiler-Specific Commands

​
Checking Your Compiler

You can make your document adapt to different compilers: 
\documentclass{article}

% Load appropriate packages based on compiler
\usepackage{ifxetex,ifluatex}
\ifxetex
    \usepackage{fontspec}
    \newcommand{\mycompiler}{XeLaTeX}
\else\ifluatex
    \usepackage{fontspec}
    \newcommand{\mycompiler}{LuaLaTeX}
\else
    \usepackage[utf8]{inputenc}
    \usepackage[T1]{fontenc}
    \newcommand{\mycompiler}{pdfLaTeX}
\fi\fi

\begin{document}
This document was compiled with \mycompiler.
\end{document}

​
Font Selection by Compiler

\documentclass{article}
\usepackage{ifxetex,ifluatex}

% Modern font setup for XeLaTeX/LuaLaTeX
\ifxetex\else\ifluatex\else
    % pdfLaTeX font setup
    \usepackage[T1]{fontenc}
    \usepackage{lmodern} % Latin Modern fonts
\fi\fi

\ifxetex
    \usepackage{fontspec}
    \setmainfont{Times New Roman}
\else\ifluatex
    \usepackage{fontspec}
    \setmainfont{Times New Roman}
\fi\fi

\begin{document}
Fonts work correctly regardless of compiler!
\end{document}

​
Special Use Cases

​
Mathematical Documents

Recommended: pdfLaTeX
  • Best package support
  • Fast compilation
  • All math packages work

​
Multilingual Documents

Recommended: XeLaTeX
  • Full Unicode support
  • Easy font switching
  • Proper script handling

​
Presentations

Recommended: pdfLaTeX with Beamer
  • Fast compilation for iterations
  • Full Beamer compatibility
  • Reliable output

​
Books with Custom Fonts

Recommended: XeLaTeX or LuaLaTeX
  • Professional typography
  • Font flexibility
  • Advanced features

​
In LaTeX Cloud Studio

LaTeX Cloud Studio makes compiler selection easy:
  1. Automatic Detection: We analyze your document and suggest the best compiler
  2. Easy Switching: Change compilers in document settings
  3. Error Handling: Clear messages if packages need a different compiler
  4. Preconfiqured: All compilers are ready to use

​
Setting Compiler in Your Document

You can specify your preferred compiler using a magic comment: 
% !TEX program = xelatex
\documentclass{article}
\usepackage{fontspec}
...

​
Troubleshooting Compiler Issues

Common compiler-related errors:
  1. “Package requires XeLaTeX/LuaLaTeX”
    • Switch to the appropriate compiler
    • Or use alternative packages
  2. “Unicode character not set up”
    • Use XeLaTeX/LuaLaTeX for full Unicode
    • Or add \usepackage[utf8]{inputenc} for pdfLaTeX
  3. “Font not found”
    • System fonts need XeLaTeX/LuaLaTeX
    • Or use LaTeX font packages with pdfLaTeX

​
Migration Guide

​
From pdfLaTeX to XeLaTeX

Remove these packages: 
% Remove these:
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

% Add this:
\usepackage{fontspec}

​
From XeLaTeX to pdfLaTeX

Replace font commands: 
% Remove:
\setmainfont{Arial}

% Add:
\usepackage{helvet}
\renewcommand{\familydefault}{\sfdefault}

​
Performance Tips

Speed up compilation:
  1. Use pdfLaTeX for drafts
  2. Switch to XeLaTeX/LuaLaTeX for final version
  3. Enable draft mode: \documentclass[draft]{article}
  4. Compile only changed parts during writing
  5. Use LaTeX Cloud Studio’s incremental compilation

​
Quick Decision Chart

Need special fonts? ──> Yes ──> XeLaTeX
         │
         No
         │
         ▼
Need Unicode? ──> Yes ──> XeLaTeX/LuaLaTeX
         │
         No
         │
         ▼
Need scripting? ──> Yes ──> LuaLaTeX
         │
         No
         │
         ▼
    pdfLaTeX (Best default choice)

​
Summary

  • Start with pdfLaTeX - It’s fast and compatible
  • Switch to XeLaTeX - When you need fonts or languages
  • Try LuaLaTeX - For advanced programmable documents
Remember: All compilers produce high-quality output. The differences are mainly about features and speed, not quality.
Next step: Learn about Paragraphs and new lines to structure your content effectively.