ResearchPublished May 2026 · Updated monthly

PDF & Image Compression Benchmark Study 2026

How much does compression actually reduce file size, and what does it cost in quality? We tested 10 PDF types across compression levels, 9 JPEG quality settings on a reference photo, and 7 image formats side by side. All results are reproducible using the methodology below.

Cite this study

ImageAndPDF Research (2026). PDF & Image Compression Benchmark Study. imageandpdf.com/compression-benchmark

Key findings

78%

Average PDF compression across all 10 types tested

75%

File size reduction at JPEG 85% quality (recommended setting)

82%

WebP vs. original JPEG at equivalent visual quality

86%

Maximum PDF reduction on greyscale scanned documents

Methodology

PDF compression

• Tool: ImageAndPDF Compress PDF (browser-based, powered by PDF.js + custom optimizer)
• Compression level: "High" (equivalent to Ghostscript /ebook preset, 150 DPI downsampling)
• All files measured in MB, rounded to 2 decimal places
• Each file tested 3× with results averaged to account for minor variation
• Original files sourced from real-world documents (contracts, reports, presentations)
• Scanned PDFs produced at stated DPI using a Canon flatbed scanner

Image compression

• Reference image: 4032×3024 JPEG taken on iPhone 15 Pro (5.1 MB original)
• JPEG quality tested using ImageAndPDF Compress Image (browser-based)
• Format comparison tested using the same reference image converted to each format
• WebP: converted using cwebp at equivalent quality parameter
• AVIF: converted using avifenc at equivalent quality parameter
• PNG: lossless and pngquant-reduced (256 colour palette) variants tested
• Visual quality assessed by 3 reviewers at 100% zoom and 200% zoom

Reproducibility: All tests can be reproduced using the free tools at imageandpdf.com. PDF tests use the Compress PDF tool; image tests use the Compress Image tool with the quality slider. Ghostscript command-line results are reproducible using the commands in our PDF compression guide.

PDF compression results by document type

High compression setting (150 DPI image downsampling + font subsetting + stream optimization). Tested May 2026.

Document type	Original	Compressed	Reduction	Image DPI	Key driver
Invoice (2 pages, text + logo)	1.1 MB	0.24 MB	−78%	,	Font subsetting main driver
Legal contract (12 pages, text only)	0.6 MB	0.15 MB	−75%	,	Primarily font + stream optimization
Research report (40 pages, charts)	8.7 MB	1.9 MB	−78%	150	Chart images downsampled to 150 DPI
Presentation (15 slides, photos)	24.3 MB	5.1 MB	−79%	150	High-res slide images main contributor
Scanned contract (5 pages, colour, 300 DPI)	12.1 MB	2.4 MB	−80%	150	JPEG re-encoding of bitmap pages
Scanned ID document (1 page, colour, 300 DPI)	3.4 MB	0.7 MB	−79%	150	Single full-colour bitmap page
Scanned receipt (greyscale, 200 DPI)	0.8 MB	0.11 MB	−86%	150	Greyscale scans compress very well
PowerPoint export (20 slides, branding heavy)	18.7 MB	3.9 MB	−79%	150	Embedded raster brand assets
Academic paper (80 pages, formulas + figures)	6.2 MB	1.8 MB	−71%	150	Vector math, moderate image count
Architectural drawing (A1, vector + raster mix)	31.4 MB	9.2 MB	−71%	200	High-res raster overlays on vector base
Average	10.73 MB	2.55 MB	−78%

What drives PDF file size

Embedded raster images

60–90% of total size

A single 300 DPI colour scan of an A4 page is ~2–4 MB. Presentations and scanned documents are almost entirely image data.

Embedded fonts

5–30% of total size

Full font files (200–500 KB each) are embedded to ensure consistent rendering. A document with 5 custom fonts may carry 2+ MB of font data.

Redundant objects

2–20% of total size

Editing, merging, and re-exporting PDFs accumulates unused objects, duplicate streams, and bloated cross-reference tables.

JPEG quality vs. file size

Reference image: 4032×3024 iPhone 15 Pro JPEG (5.1 MB original). File sizes rounded to 2 decimal places.

Quality	File size	vs. original	Visual quality	Compression artifacts
100%	5.1 MB	baseline	Perfect, reference	None
95%	3.2 MB	−37%	Excellent	None
90%	2.1 MB	−59%	Excellent, imperceptible	None
85%★ Recommended	1.3 MB	−75%	Very good, recommended	None
80%	0.95 MB	−81%	Good	Trace (extreme zoom only)
75%	0.71 MB	−86%	Good	Minor (visible at 200%+)
70%	0.55 MB	−89%	Acceptable	Visible on gradients
60%	0.38 MB	−93%	Degraded	Blocking on edges
50%	0.28 MB	−95%	Poor	Obvious at normal view

85% JPEG quality is the industry-standard recommendation: 75% size reduction with no artifacts visible to the human eye at normal screen viewing distances.

Image format comparison, same photo, 7 formats

Same reference image (4032×3024 iPhone photo, 5.1 MB JPEG original) converted to each format at comparable quality settings.

Format	File size	vs. JPEG 85%	Lossless	Transparency	Browser support	Best for
JPEG 85%	1.3 MB	reference	,	,	All	Photos, general web
WebP 85%	0.91 MB	-30%	,	✓	All modern	Web, progressive web apps
AVIF 85%	0.62 MB	-52%	,	✓	Chrome, Firefox, Safari 16+	Web (modern browsers only)
PNG (lossless)	4.8 MB	+269%	✓	✓	All	Logos, screenshots, text graphics
PNG (pngquant 256 colours)	1.9 MB	+46%	,	✓	All	Graphics where PNG transparency required
HEIC	0.85 MB	-35%	,	,	Safari (limited elsewhere)	iPhone camera, Apple devices
GIF	3.2 MB	+146%	,	✓	All	Animations (photos: avoid)

WebP at equivalent quality is 30% smaller than JPEG. AVIF is even more efficient but requires Chrome 85+, Firefox 93+, or Safari 16+. For broad compatibility, JPEG 85% remains the safe default.

Ghostscript PDF presets, reduction vs. quality

Tested on the 12.1 MB scanned contract (5 pages, colour). Ghostscript version 10.03.

Preset	Image DPI	Reduction	Quality level	Use case
/screen	72	85–92%	Low, for on-screen reference only	Maximum size reduction, legibility > sharpness
/ebook★ Recommended	150	75–85%	Good, recommended for most uses	Digital submission, email, web
/printer	300	40–60%	High, full print quality	Print-ready output
/prepress	300	20–40%	Maximum, colour-managed	Commercial print, colour-accurate proof

Practical recommendations from the data

Compressing a PDF for email or portal upload

Use browser tool at high compression. Expected: 75–80% reduction. A 10 MB document becomes ~2 MB.

→ Compress PDF

Compressing a JPEG photo for web or social media

Use 85% JPEG quality. Expected: 75% reduction with no visible quality loss. For web, convert to WebP for an additional 30% saving.

→ Compress Image

Scanned document is still too large after compression

Convert to greyscale first, greyscale scans compress 86% vs 80% for colour. Then compress. As a last resort, use Ghostscript /screen preset (72 DPI).

→ PDF to Greyscale

Choosing an image format for a website

WebP at 85% quality: 30% smaller than JPEG with identical perceived quality. Use AVIF if you can accept limited browser support (Chrome, Firefox, Safari 16+). Keep PNG only for logos and graphics with transparency.

→ Convert Image Format

Use this data

This benchmark study is free to cite, link to, or reference in your own articles. If you reproduce tables or statistics, please attribute with a link to this page.

Data updated monthly as we add new file types and tool versions. Methodology section updated whenever the testing process changes.

Suggested citation

ImageAndPDF Research (May 2026). PDF & Image Compression Benchmark Study. https://imageandpdf.com/compression-benchmark

Tools referenced in this study

→

Compress PDF

Browser-based PDF compression, no upload to server

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Compress Image

JPEG, PNG, WebP compression with quality slider

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Convert Image Format

Convert between JPEG, PNG, WebP and other formats

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PDF to Greyscale

Convert colour PDFs to greyscale before compression