Does image compression happen on my device?

Yes. All compression is performed locally in your browser using the Canvas API. Your images are never uploaded to any server.

Which image formats are supported?

The tool supports JPEG, PNG, and WebP. For PNG files, the tool converts to JPEG for lossy compression unless you choose WebP output.

Will compression reduce the image quality?

Lossy compression reduces file size by discarding some image data. For most use cases, a quality setting of 70–85% is visually indistinguishable from the original.

Is there a file size limit?

There is no strict limit, but very large files (over 20 MB) may take a few seconds to process depending on your device.

Image Compressor

Compress PNG, JPG, and WebP images right in your browser. No uploads, no accounts — your images never leave your device.

Drag & drop images here

or click to browse

PNGJPGWEBP·up to 20 images

Why use our online Image Compressor?

Browser-based compression uses the Canvas API to reduce image file size without sending your photos to a server. No file size limits, no account required — compress and download instantly.

How to use Image Compressor

1
Upload your image
Drag and drop an image onto the upload area, or click to browse your files. Supports JPG, PNG, and WebP formats.
2
Adjust the quality slider
Use the quality slider to control the compression level. Lower values produce smaller files; higher values preserve more detail.
3
Preview the result
The compressed image preview and the new file size appear immediately. Compare it with the original to check visual quality.
4
Download the compressed image
Click the download button to save the compressed image to your device. No sign-up required.

How browser-based image compression works

This tool compresses images using the browser's Canvas API rather than sending your files to a server. The process works by drawing your image onto an invisible HTML canvas element and then calling canvas.toBlob() with a quality value between 0 and 1. For JPEG output, lower quality values instruct the encoder to use more aggressive DCT block averaging, discarding high-frequency detail that the eye is least sensitive to.

PNG files present a different challenge: PNG uses lossless compression, so re-encoding a PNG as PNG never reduces its file size beyond the original compression. To achieve meaningful size reduction, this tool converts PNG to JPEG (or WebP), which uses lossy compression. If you need to maintain transparency — which JPEG does not support — choose WebP output instead.

The trade-off is always quality versus file size. For photos, a quality setting of 75–85% is visually indistinguishable from the original at typical screen sizes. For images with text, sharp edges, or flat colors, quality below 80% may introduce visible JPEG artifacts around high-contrast boundaries.

JPG vs PNG vs WebP — choosing the right format

JPEG (JPG) is the right choice for photographs and images with continuous tonal gradients. Its lossy compression achieves very small file sizes — typically 3–10× smaller than lossless formats — with acceptable quality at 75–90% settings. JPEG does not support transparency.

PNG is a lossless format best suited for screenshots, illustrations, logos, icons, and any image where sharp edges and text must remain crisp. PNG supports full transparency (alpha channel) and produces larger files than JPEG for photographic content, but smaller files for graphics with large flat-color areas.

WebP is a modern format developed by Google that supports both lossy and lossless compression, full transparency, and achieves 25–35% smaller files than JPEG at equivalent quality. Browser support for WebP is now universal in Chrome, Firefox, Safari 14+, and Edge. Use WebP when you control the delivery environment and want the best compression-to-quality ratio. For maximum compatibility — especially email, social media uploads, or any environment outside the web browser — stick with JPEG or PNG.

Compression vs resizing — which reduces file size more?

Compression and resizing are two separate techniques that reduce file size in different ways. Compression reduces the amount of data needed to represent each pixel. Resizing reduces the number of pixels in the image. For the web, combining both usually produces the best results.

If an image is 4000 × 3000 pixels but will only ever be displayed at 800 × 600 on screen, resizing it down first eliminates 75% of the data before any compression is applied — achieving far greater size reduction than compression alone. The rule of thumb: never serve an image at a resolution larger than it will be displayed.

After resizing, apply compression. For a 800 × 600 JPEG at 85% quality, you can typically achieve files under 100 KB for most photographic content. Google's Core Web Vitals guidelines recommend keeping images under 200 KB and using modern formats like WebP. Tools like Lighthouse and PageSpeed Insights flag oversized images as one of the most impactful performance improvements for most websites.

Images and Core Web Vitals — what the LCP metric measures

Google's Core Web Vitals include a metric called Largest Contentful Paint (LCP), which measures how long it takes for the largest visible element in the viewport to finish rendering. For most pages, the LCP element is a hero image, banner, or above-the-fold photograph. A good LCP score is under 2.5 seconds; above 4 seconds is rated poor.

Oversized images are the most common cause of poor LCP. If the LCP image is a 3 MB JPEG that must download before it renders, even a fast network connection produces a poor score. Compressing the hero image to under 200 KB — combined with WebP format — typically makes the single largest improvement to LCP on image-heavy pages.

Beyond file size, LCP is also affected by image loading strategy. The HTML loading attribute (loading="lazy") defers off-screen images but should never be applied to the LCP image — lazy loading the hero image delays it by design. Instead, add fetchpriority="high" to the LCP image element to tell the browser to prioritize its download. Use srcset and sizes attributes to serve appropriately sized images to different screen resolutions rather than one oversized version to every device.

Frequently Asked Questions

Does image compression happen on my device?: Yes. All compression is performed locally in your browser using the Canvas API. Your images are never uploaded to any server.
Which image formats are supported?: The tool supports JPEG, PNG, and WebP. For PNG files, the tool converts to JPEG for lossy compression unless you choose WebP output.
Will compression reduce the image quality?: Lossy compression reduces file size by discarding some image data. For most use cases, a quality setting of 70–85% is visually indistinguishable from the original.
Is there a file size limit?: There is no strict limit, but very large files (over 20 MB) may take a few seconds to process depending on your device.