How to Convert Multiple Images to a Single PDF

Why Combine Multiple Images Into One PDF?

Loose image files are inconvenient to share, organize, and print. When you have 15 scanned pages of a contract, 30 photos from a product shoot, 8 whiteboard captures from a meeting, or 50 slides exported as images — you need them in a single, ordered document. PDF is that document.

Combining images into a PDF transforms a scattered collection into a structured document with sequential pages, consistent sizing, and a single file that can be emailed, uploaded, printed, or archived. Recipients get one file to open instead of a ZIP archive of images to extract and sort.

The process is straightforward, but doing it well — with correct page order, proper sizing, consistent orientation, and optimal file size — requires attention to a few key settings.

Understanding the Process

When you combine images into a PDF, each image becomes a page. The converter must decide:

1. Page dimensions — What size is each PDF page? (A4, Letter, or custom to match the image)
2. Image placement — How does the image fit on the page? (Fill, fit, center, stretch)
3. Image compression — Is the original JPEG data preserved or re-encoded?
4. Page order — What sequence do the images appear in?
5. Orientation — Portrait or landscape, per-page or uniform?

Step-by-Step Guide

Step 1: Prepare Your Images

Before combining, ensure your images are ready:

File naming for correct order. Most converters process files in alphanumeric order by filename. If your files are named photo1.jpg, photo10.jpg, photo2.jpg, they will sort as 1, 10, 2 (not 1, 2, 10). Use zero-padded numbers: photo01.jpg, photo02.jpg, photo10.jpg. Or use full dates: 2026-02-24-scan-001.jpg.

Consistent orientation. If some images are rotated incorrectly (common with smartphone photos), fix rotation before combining. A single sideways page in a 20-page document looks unprofessional. Check EXIF orientation tags — some images appear correct in viewers that read EXIF but display sideways in tools that ignore it.

Resolution consistency. Mixing a 300 DPI scan with a 72 DPI screenshot produces pages with dramatically different text sizes unless the converter normalizes them to a common page size. If possible, ensure all images are at similar resolutions.

Crop and clean. Remove unnecessary borders, margins, and blank areas from scanned images. A scanner often captures the scanner lid as a dark border — crop this out before combining.

Step 2: Choose Page Size and Layout

For scanned documents: Use the paper size that matches the originals (A4 or Letter), zero margins, and fit-within mode. This produces a PDF that looks like the original paper documents.

For photo albums or portfolios: Match page size to image dimensions (or use a standard photo size like 4x6 or 5x7), zero margins, and fill mode.

For mixed content (photos, screenshots, diagrams): Use a fixed page size (A4 or Letter), small margins (10mm), and fit-within mode. All images display at their native aspect ratio on consistently-sized pages.

Step 3: Set Compression and Quality

For scanned documents where text clarity matters, avoid heavy JPEG compression — text becomes blurry and unreadable below quality 70. If your scans are already JPEG, the best converters embed the original JPEG data without re-encoding (zero additional quality loss).

For very large collections (100+ images), compression matters significantly. A 100-page document at 2 MB per page is 200 MB. At 500 KB per page (JPEG quality 85), it is 50 MB — much more practical for email and upload.

Step 4: Upload and Combine

Upload your images to our JPG to PDF converter or PNG to PDF converter. Both support multi-file upload for creating multi-page PDFs. Our converter processes multiple images in the order you arrange them and combines them into a single output PDF.

Step 5: Verify the Output

After conversion, check:

• Page order is correct (first page is page 1 of the intended document)
• All pages are present (count pages vs. input images)
• Orientation is correct on every page
• Text readability on scanned documents (zoom to 100% and check)
• File size is appropriate for your delivery method

Advanced Workflows

Adding OCR to Scanned Image PDFs

A PDF created from scanned images contains only images — no searchable text. For documents that need to be searchable (legal files, archived correspondence, reference materials), apply OCR after combining. Our PDF OCR tool adds a hidden text layer beneath each page image, making the content searchable while preserving the visual appearance.

Creating PDF/A from Images

For archival purposes (legal documents, institutional records), the output PDF should comply with PDF/A standards. This requires embedding color profiles and metadata beyond what a basic image-to-PDF conversion produces. See our PDF/A compliance guide for requirements.

Mixed Format Inputs

Real-world batches often contain a mix of formats: some pages scanned as JPEG, others as PNG (screenshots), and a few as TIFF (high-quality scans). A good converter handles mixed inputs transparently, applying appropriate compression per image (lossless for PNG/TIFF, preserve-original for JPEG).

Quality and Settings Tips

Page order is the most common error. Double-check the sort order before converting. Renaming files with numeric prefixes (001_, 002_, etc.) is the most reliable way to control order across all converters and operating systems. Some file systems sort case-sensitively (uppercase before lowercase), which can produce unexpected ordering.

Direct JPEG embedding produces the best results for JPEG sources. When your input images are already JPEG, the optimal conversion embeds the original JPEG compressed data directly into the PDF without decompressing and recompressing. This is lossless (no additional quality degradation) and fast. Some converters re-encode all images, which is unnecessary and harmful for JPEG inputs.

Use lossless compression for text-heavy content. Screenshots, diagrams, and text documents with sharp edges benefit from PNG/Flate compression in the PDF. JPEG compression blurs text edges, especially at lower quality settings. If your source is PNG, keep it lossless in the PDF.

Consider the recipient's needs. A 200 MB PDF of full-resolution photos is impractical for email. Resize images before combining (long edge 2000px is sufficient for screen viewing) or use higher JPEG compression. For printing, maintain full resolution.

For individual image-to-PDF conversions (one image per PDF), see our dedicated JPG to PDF and PNG to PDF guides.

Common Issues and Troubleshooting

Pages are in the wrong order. File sorting is typically alphanumeric. Rename files with zero-padded numbers before uploading. On macOS, Finder's "Sort by Name" uses natural sorting (1, 2, 10), but command-line tools and web uploads often use strict alphanumeric sorting (1, 10, 2).

Some pages are rotated sideways. Smartphone photos often store rotation in EXIF metadata rather than rotating the actual pixels. Some converters ignore EXIF orientation. Our converter reads EXIF orientation and applies it correctly. If a page is still wrong, manually rotate the source image before uploading.

Output PDF is huge. Check whether the converter is embedding uncompressed image data instead of using JPEG compression. A 20-page document of 5 MB photos should not exceed 100 MB (and 50-60 MB is more typical). If files are dramatically larger than expected, the converter may not be optimizing compression.

Text in scanned images is blurry. Either the original scan resolution was too low (below 200 DPI) or the converter re-compressed the JPEG at a low quality setting. For text documents, scan at 300 DPI minimum and use quality 85+ for JPEG compression.

PDF cannot be opened in some viewers. Very large PDFs (500+ pages, 1+ GB) may cause issues in lightweight PDF viewers. Split into smaller documents (50-100 pages each) if the recipient reports problems. Our PDF split tool can divide large PDFs after creation.

Mixed page sizes in the output. When "match image size" is selected and images have different dimensions, each PDF page will be a different size. This is correct behavior for that setting. For uniform pages, use a fixed page size (A4 or Letter) and fit images within.

Conclusion

Combining multiple images into a single PDF is a matter of getting the details right: correct page order (use numbered filenames), appropriate page sizing (match your output medium), optimal compression (preserve original JPEG data when possible), and proper orientation (check EXIF tags). For scanned documents, add OCR to make the PDF searchable. For archival, consider PDF/A compliance.

Ready to convert? Try our free JPG to PDF converter with multi-file support — no registration required.