How to Combine Multiple Images Into One PDF

Whether you’re creating a photo portfolio, combining scanned document pages, or assembling a presentation, merging multiple images into one PDF is a common need. Here are the best free methods.

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Method 1: AltoUnlockPDF Multi-Image Converter

Our Image to PDF tool handles batch conversions:

1. Click “Upload Images” and select multiple files (or drag and drop)
2. Reorder images by dragging them into the right sequence
3. Choose page size and image fit (fill page, fit with margins, original size)
4. Click Convert → Download your combined PDF

Supports: JPG, PNG, TIFF, BMP, GIF, WebP

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Method 2: Windows (Print Method)

1. Select all image files in File Explorer (Ctrl+A or click + Shift+click)
2. Right-click → Print
3. Set Printer to “Microsoft Print to PDF”
4. Choose paper size and layout
5. Click Print → save the output PDF

The images appear in the PDF in the order they were selected (which Windows sorts by filename by default).

Tip: Rename your files with numeric prefixes (01_image.jpg, 02_image.jpg) to control page order.

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Method 3: Mac — Quick Actions or Preview

Via Quick Actions (macOS Mojave+):

1. Select all images in Finder
2. Right-click → Quick Actions → Create PDF
3. One PDF with each image as a page

Via Preview App:

1. Open the first image in Preview
2. Show Thumbnails panel (View → Thumbnails)
3. Drag additional images into the thumbnail panel in the correct order
4. File → Export as PDF

This is the most flexible method on Mac — you can precisely control page order by dragging thumbnails.

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Method 4: Command Line (ImageMagick)

ImageMagick is a powerful free tool for command-line image processing:

# Install on macOS
brew install imagemagick

# Install on Ubuntu
sudo apt install imagemagick

# Combine images into PDF
convert image1.jpg image2.jpg image3.jpg combined.pdf

# Combine all JPGs in current folder (alphabetical order)
convert *.jpg output.pdf

# With specific DPI
convert -density 150 *.jpg output.pdf

# Resize all images to A4 first
convert -resize 2480x3508 *.jpg output.pdf

Note: ImageMagick may have policy restrictions on PDF output. If you get an error, edit /etc/ImageMagick-6/policy.xml and find/change the PDF policy from “none” to “read|write”.

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Method 5: Python (img2pdf — Lossless)

For developers, img2pdf is the best Python library because it inserts images into the PDF without re-encoding them — preserving original quality at the smallest possible file size:

import img2pdf
from PIL import Image
import os

def combine_images_to_pdf(image_paths, output_path, page_size='A4'):
    # Optional: resize to consistent dimensions
    a4_width, a4_height = img2pdf.mm_to_pt(210), img2pdf.mm_to_pt(297)
    
    with open(output_path, 'wb') as f:
        f.write(img2pdf.convert(
            image_paths,
            layout_fun=img2pdf.get_layout_fun((a4_width, a4_height))
        ))

# Combine all JPGs in a folder
folder = './scanned_pages'
images = sorted([
    os.path.join(folder, f)
    for f in os.listdir(folder)
    if f.lower().endswith(('.jpg', '.jpeg', '.png'))
])
combine_images_to_pdf(images, 'combined_document.pdf')

pip install img2pdf

img2pdf is exceptionally fast — 100 JPG pages in under a second — and produces the smallest possible PDF files.

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Controlling Image Order

Page order in the final PDF depends on the order images are passed to the tool. Plan ahead:

Method	Order Control
AltoUnlockPDF	Drag to reorder in UI
Windows Print	Alphabetical filename order
Mac Preview	Drag thumbnails to reorder
ImageMagick	Order of filenames in command
Python img2pdf	Order of list passed to convert()

Best practice: Number your files: 001_page.jpg, 002_page.jpg, etc. Alphabetical sorting then matches intended order in every tool.

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File Size Considerations

Combining high-resolution JPGs can create very large PDFs. Options:

1. Reduce image resolution before combining — 150 DPI is enough for screen; 300 DPI for print
2. Use img2pdf — no re-encoding means minimum file size
3. Compress the final PDF — use our PDF Compress tool after combining
4. Use JPEG compression settings — avoid converting JPGs to PNG before combining (PNG in PDF is much larger)