How to Convert Images to PDF — Combine Photos into One Document

Why Convert Images to PDF?

Images are great for viewing, but PDFs are better for sharing, printing, and archiving. A folder of 20 JPG scans is awkward to email — a single PDF is professional. A set of product photos needs to go to a printer as one file. Receipts captured with a phone camera need to be compiled into an expense report. Converting images to PDF solves all of these.

PDFs also preserve page order, support consistent print layouts, and are the expected format for legal documents, academic submissions, and business correspondence. When someone says "send me the document," they almost always mean a PDF.

Methods for Converting Images to PDF

1. Browser-Based Conversion

FileKit's Images to PDF tool lets you upload multiple images (JPG, PNG, WebP, or HEIC), drag to reorder them, choose a page size (A4, Letter, or auto-fit), and download a single PDF. The conversion uses the pdf-lib library running entirely in your browser. For JPG-only workflows, there's also a dedicated JPG to PDF tool.

2. macOS Preview

Select multiple images in Finder, right-click → Open With → Preview. In Preview, select all thumbnails in the sidebar, then File → Print → Save as PDF. This approach is quick but gives limited control over page size, margins, and image placement.

3. Command Line with ImageMagick

# Convert multiple images to a single PDF
magick img1.jpg img2.jpg img3.jpg output.pdf

# Resize images to fit A4 before conversion
magick *.jpg -resize 595x842 -gravity center -extent 595x842 output.pdf

ImageMagick is powerful for batch processing. The resize-and-extent approach centers each image on an A4-sized page (595 × 842 points at 72 DPI), adding white space as needed.

Page Size and Layout Options

How images fit onto PDF pages depends on the page size setting:

• Auto-fit (match image size). Each page is exactly the size of the image. No margins, no white space. Best for photo portfolios and presentations where you want edge-to-edge images.
• A4 (210 × 297 mm). Standard paper size used internationally. Images are scaled to fit within the page with margins. Best for documents intended for printing in most countries.
• Letter (8.5 × 11 in). Standard paper size in the US and Canada. Use this when the recipient will print on US-standard paper.

Orientation (portrait vs. landscape) can be set globally or auto-detected per image based on its aspect ratio.

Image Quality Considerations

The quality of your PDF depends entirely on the source images:

• Resolution matters. A 640 × 480 phone photo will look blurry when scaled to fill an A4 page. For print-quality results, use images that are at least 2000 pixels on the long edge.
• JPG artifacts carry over. If your source JPGs are heavily compressed, the artifacts will be visible in the PDF. Use the highest quality originals available.
• PNG vs. JPG. PNG images are lossless but produce larger PDFs. JPG images are smaller but may show compression artifacts. For documents with text and diagrams, PNG is better. For photos, JPG is fine.

Common Workflows

Compiling Scanned Receipts

Photograph each receipt with your phone, transfer the images to your computer (or use the tool directly on your phone), arrange in chronological order, and convert to PDF. The result is a single file ready to attach to an expense report or tax filing.

Creating a Photo Portfolio

Select your best images, arrange them in presentation order, and convert with auto-fit page sizing. Each image gets its own page at full resolution. After conversion, consider compressing the PDF if the file size is too large for email.

Submitting Documents Online

Many government forms, university applications, and job portals require PDF uploads. If you have scanned documents as individual images, combine them into a single PDF. Add page numbers for documents with multiple sections.

HEIC Photos from iPhone

iPhones capture photos in HEIC format by default. Many tools don't accept HEIC directly. You have two options: convert HEIC to JPG first, then create the PDF, or use FileKit's HEIC to PDF tool which handles the conversion in one step.

After Conversion

• Check page order. Verify that pages appear in the intended sequence.
• Compress if needed. High-resolution images produce large PDFs. Compression can cut the file size by 40-70% with minimal visible quality loss.
• Add text if needed. Image-based PDFs are not searchable. Run OCR to add a searchable text layer if the images contain text you need to find later.