How to Convert JPG to PDF Without Losing Quality

The typical JPG-to-PDF converter takes your image, runs it through JPEG compression again, and embeds the result. The output looks fine at a glance but zooms soft, and you've permanently degraded your source. There's a better way.

Why Re-Encoding a JPEG Destroys Quality

JPEG uses lossy compression. Every time you re-encode, you add another generation of artefacts — even at quality 95. A JPEG that's been through three converters will be noticeably softer than the original, with visible blocking artefacts around high-contrast edges.

The correct approach is to embed the JPEG bytes directly into the PDF stream without re-encoding. The PDF format natively supports JPEG-compressed image streams — you can store the original bytes as-is, meaning zero quality loss.

// Embed JPEG bytes directly into PDF — no recompression
import { PDFDocument } from 'pdf-lib';

const pdfDoc = await PDFDocument.create();
const jpgBytes = new Uint8Array(await file.arrayBuffer()); // original bytes

// embedJpg stores the original JPEG stream — no quality loss
const jpgImage = await pdfDoc.embedJpg(jpgBytes);

// Page sized exactly to the image (72 DPI = 1px per point in PDF units)
const page = pdfDoc.addPage([jpgImage.width, jpgImage.height]);
page.drawImage(jpgImage, { x: 0, y: 0, width: jpgImage.width, height: jpgImage.height });

const pdfBytes = await pdfDoc.save();

Setting the Right Page Size for Print

PDF page sizes are in points (1 point = 1/72 inch). For a photo intended to print at A4 at 300 DPI, the source image needs to be 2480×3508 pixels. Scaling a smaller image up in the PDF adds interpolated pixels — it won't be sharp.

• ●Letter (8.5×11″) at 300 DPI: 2550×3300px source
• ●A4 (210×297mm) at 300 DPI: 2480×3508px source
• ●A5 (148×210mm) at 300 DPI: 1748×2480px source
• ●Screen only: any size — DPI doesn't affect on-screen display

PNG and WebP Sources

PNG files are lossless — any conversion to JPEG is the first lossy step, so choose quality carefully. WebP is not a native PDF image format and must be converted to JPEG or PNG first. Our Image to PDF converter embeds JPEG data directly without re-encoding.