\engines{comparison}
LuaLaTeX vs pdfLaTeX
Both engines produce high-quality PDFs, but LuaLaTeX adds a full Lua scripting runtime and modern font loading at the cost of speed. This guide covers every meaningful difference so you can pick the right engine for each document.
- Speed matters — fastest engine available
- Maximum package compatibility required
- Standard Latin text documents
- Microtype kerning and protrusion needed
- Lua scripting for dynamic content generation
- Modern font loading with fontspec
- Unicode text beyond basic Latin
- Complex algorithmic typesetting
\section{Technical differences}
Technical Differences
Understanding the underlying architecture helps you predict behavior when packages interact, fonts are loaded, or scripts run.
Lua scripting capability
LuaLaTeX embeds a full Lua 5.3 interpreter. You can write procedural code, loop over data, call tex.print(), and manipulate the typesetting engine programmatically. pdfLaTeX has no such scripting layer.
Font loading
LuaLaTeX uses fontspec to load any OpenType or system font by name — no manual .tfm configuration. pdfLaTeX relies on the TeX font system and requires inputenc + fontenc for proper encoding.
Unicode support
LuaLaTeX reads UTF-8 natively at the engine level. pdfLaTeX approximates Unicode through the inputenc package, which covers most Latin scripts but requires workarounds for CJK, Arabic, or advanced mathematical symbols.
Compilation speed
pdfLaTeX is the fastest LaTeX engine — typically 0.6–1 second for a simple document. LuaLaTeX initialises the Lua VM and a larger font system, making it 2–3× slower on average. For CI pipelines or live preview, this difference is significant.
\section{Feature comparison}
Feature Comparison
| Feature | pdfLaTeX | LuaLaTeX |
|---|---|---|
| Unicode input | Via inputenc | Native |
| System fonts | No | Yes (fontspec) |
| Lua scripting | No | Yes (luacode) |
| Compilation speed | Fast (~0.8s) | Slower (~2–3×) |
| Package compat. | Excellent | Good |
| Microtype | Full support | Partial |
| RTL languages | Limited | Yes (luabidi) |
| Memory usage | Low | Higher (Lua VM) |
\section{Code examples}
Code Examples
Side-by-side minimal documents for each engine.
% pdfLaTeX — fast, maximum compatibility
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{microtype}
\begin{document}
Standard pdfLaTeX document. Fast compilation, excellent package support.
$f(x) = \int_0^x t^2\, dt = \frac{x^3}{3}$
\end{document}% LuaLaTeX — Lua scripting, modern fonts
\documentclass{article}
\usepackage{fontspec}
\usepackage{luacode}
% Lua scripting inside LaTeX
\begin{luacode}
local n = 10
local sum = 0
for i = 1, n do sum = sum + i end
tex.print("Sum 1.." .. n .. " = " .. sum)
\end{luacode}
\begin{document}
LuaLaTeX natively handles Unicode and supports Lua scripts.
\end{document}\section{When to use LuaLaTeX}
When to Use LuaLaTeX
LuaLaTeX is the right choice in these specific scenarios.
Dynamic content generation
Use Lua loops and conditionals to generate repetitive table rows, chapter lists, or structured output programmatically inside LaTeX.
Custom font rendering
Load any OpenType or system font by name with fontspec — ideal for branded reports, custom typography, or non-Latin scripts.
Complex algorithms
Embed number-crunching Lua code directly in your document: statistics, transformations, or data formatting before typesetting.
Modern arXiv submissions
Some newer journal templates and arXiv submissions explicitly require or prefer LuaLaTeX for modern font and Unicode handling.
\section{Migration guide}
Migrating pdfLaTeX → LuaLaTeX
Most pdfLaTeX documents compile under LuaLaTeX with a few preamble changes.
| Action | Package / command |
|---|---|
| Remove | \usepackage[utf8]{inputenc} |
| Remove | \usepackage[T1]{fontenc} |
| Add | \usepackage{fontspec} |
| Optional | \usepackage{luacode} |
| Consider | \usepackage{polyglossia} |
\api{FormaTeX}
Using LuaLaTeX via the API
Pass "engine": "lualatex" in your compile request to select LuaLaTeX.
curl -X POST https://api.formatex.io/v1/compile/sync \
-H "Authorization: Bearer $FORMATEX_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"engine": "lualatex",
"source": "\\documentclass{article}\\usepackage{fontspec}\\begin{document}Hello\\end{document}"
}' \
--output document.pdf