Compress Image FREE | Reduce Photo File Size Without Losing Quality

Compress JPG, PNG, or WebP images by adjusting the quality slider. See before and after file sizes live. Download the compressed image in your chosen format. No upload — runs entirely in your browser. Keep full control over quality versus file size.

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Quality Control

Live Size Compare

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Image Compressor

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Frequently Asked Questions

For photographs shared on the web or via email, a quality setting of 75-85% is the standard recommendation — it produces images that are visually indistinguishable from the original at typical viewing sizes while reducing file size by 60-80%. For images that will be printed, use 90-95% quality. For thumbnails or background images, 60-70% is often sufficient. The live file size display helps you find the right balance for your specific image.

PNG is a lossless format — the quality slider has no effect when PNG is selected as output because PNG always encodes at full quality. The only compression available in PNG is lossless dictionary compression (deflate), which the browser applies automatically. If file size reduction is your goal, switch to JPG or WebP output where the quality slider directly controls the lossy compression level.

WebP is a modern image format developed by Google that uses a more advanced compression algorithm than JPEG. At the same perceptual quality level, WebP files are typically 25-35% smaller than equivalent JPEG files. All modern browsers (Chrome, Firefox, Safari 14+, Edge) support WebP natively. It is the recommended format for web images where file size and page speed are priorities.

No. This tool compresses the image quality (encoding bit depth and detail) without changing the pixel dimensions. The output image has exactly the same width and height as the input. To reduce dimensions, use the Image Resizer. Combining both dimension reduction and quality compression produces the smallest possible output files for web use.

The Original Size shown is the exact byte size of the file you uploaded, read directly from the File object. The Compressed Size is the byte size of the Blob produced by the canvas.toBlob() API after applying your chosen quality and format settings. The savings percentage shows how much smaller the compressed version is relative to the original. The comparison updates live as you move the quality slider or change the format.

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Free Image Compressor Online — Reduce JPG PNG and WebP File Sizes Without Losing Quality

Image file size is one of the most significant factors affecting website loading speed, email deliverability, storage costs, and social media upload times. Google's Core Web Vitals and PageSpeed Insights consistently rank large unoptimised images as one of the leading causes of slow page loads. A raw JPEG photograph from a modern smartphone can easily be 4-8 MB. After proper compression at a quality of 80%, the same image is typically 200-600 KB — a reduction of 85-95% with no perceptible quality loss at typical display sizes. The Image Compressor on OneDocPDF gives you direct, real-time control over this process using the browser's native canvas.toBlob() API.

Understanding the relationship between quality and file size helps you make the right choice for each use case. The quality slider in this tool controls the amount of lossy compression applied by the JPEG or WebP encoder. At 100% quality, the encoder applies minimal compression and preserves near-original detail. At 80%, the encoder aggressively discards high-frequency detail that is usually imperceptible, producing dramatically smaller files. At 60%, compression artefacts begin to appear on fine details and text. The live before-and-after comparison panel makes it easy to find your specific ideal balance.

WebP compression stands out as the most efficient option for web use. At a WebP quality of 80%, you typically get smaller files than JPEG at 90% quality while maintaining equivalent or better visual quality. All browsers released after 2020 support WebP natively, making it safe for website images, blog posts, e-commerce product photos, and landing page banners. For images that need to be emailed to unknown recipients or used in documents, JPEG remains the most universally compatible choice.

The most effective strategy for minimising web image file sizes combines two steps: first reduce the pixel dimensions to exactly what is needed for display using our Image Resizer, then apply quality compression using this tool. A 3000x2000 photograph scaled down to the 1200-pixel display width and then compressed at 80% quality produces a file roughly 40-60x smaller than the original — from 6 MB to 100-150 KB — with no visible quality degradation at the display size.

Explore the full range of image tools available free on OneDocPDF: resize images to specific dimensions, convert image formats between JPG, PNG, and WebP, convert images to PDF for document workflows, and add watermarks to protect your images. We also offer free PDF tools including a PDF compressor — all on OneDocPDF, free forever.