The Complete Guide to HTML-to-PDF Conversion in 2026

The fundamentals

HTML-to-PDF conversion takes an HTML document with CSS styling and produces a PDF file. The challenge is that HTML is designed for screens (infinite scrolling, responsive layout) while PDF is designed for print (fixed pages, exact positioning).

Approaches

1. Browser-based (Puppeteer, Playwright)

Load the HTML in a headless browser, call page.pdf(). Pros: supports JavaScript, renders exactly like Chrome. Cons: slow, memory-hungry, requires Chromium binary.

2. Native engines (pdfRelay, Prince, WeasyPrint)

Parse HTML and CSS directly without a browser. Pros: fast, lightweight, consistent output. Cons: may not support every CSS feature (though pdfRelay supports flexbox, grid, and most modern CSS).

3. Template libraries (pdf-lib, jsPDF, React-PDF)

Build the PDF programmatically with code instead of HTML. Pros: full control over every element. Cons: you're writing imperative code to position every element — no CSS, no responsive layout, no reuse of existing HTML skills.

CSS for print

The key CSS features for PDF generation:

@page {
  size: A4;
  margin: 20mm;
}

@page :first {
  margin-top: 40mm; /* Extra top margin on first page */
}

.page-break {
  break-before: always; /* Force a page break */
}

.no-break {
  break-inside: avoid; /* Keep element on one page */
}

With pdfRelay, your existing CSS just works. Flexbox, Grid, custom fonts, background colors — the Rust engine handles it all. No proprietary markup languages. No coordinate-based layouts. Just HTML and CSS — the standards every web developer already knows.