How does image compression work?

This tool uses the browser's built-in Canvas API to re-encode images at a lower quality level. For JPEG and WebP, it uses lossy compression — reducing file size by discarding visual details that are hard to notice. PNG compression works by re-encoding through canvas, which can reduce file size when the original is unoptimized.

Are my images uploaded to a server?

No. All compression happens entirely in your browser using JavaScript and the Canvas API. Your images never leave your device. Nothing is uploaded, stored, or transmitted.

What image formats are supported?

JPEG, PNG, WebP, GIF, and BMP files can be loaded. Output is available as JPEG, PNG, or WebP. The tool automatically selects the best output format based on input, but you can override it.

How much can I reduce file size?

Typically 40-80% reduction for JPEG at quality 70-80%. Results vary by image content — photos compress better than graphics with sharp edges. The tool shows before/after sizes and savings percentage in real time.

Will compression affect image quality?

At quality levels of 70-85%, most images show no visible difference to the human eye. The side-by-side preview lets you compare before and after to find the right balance for your needs.

Free & Private

Image Compressor

Reduce image file size without losing visible quality. Supports JPEG, PNG, and WebP. Everything runs in your browser — nothing is uploaded.

Drop images here or click to browse

Select one or multiple images at once

Supports JPEG, PNG, WebP, GIF, BMP

Original—

Compressed—

Quality 80%

Output Format

Max Width (optional)

How Image Compression Works

Image compression reduces file size by removing data that contributes little to perceived visual quality. There are two approaches: lossy compression, which permanently discards some data, and lossless compression, which reduces size without any data loss.

Lossy vs. Lossless

JPEG and WebP use lossy compression — they selectively remove high-frequency detail that the human eye is least sensitive to. This can achieve dramatic file size reductions (60-80%) with minimal visible impact. PNG uses lossless compression by default, preserving every pixel exactly, which results in smaller savings but perfect fidelity.

JPEG at 80% quality: typically 60-75% smaller
WebP at 80% quality: typically 65-80% smaller
PNG re-encode: typically 10-40% smaller

When to Use Each Format

Format	Best For	Compression
JPEG	Photographs, complex images	Lossy, excellent size reduction
PNG	Graphics, logos, screenshots, transparency	Lossless, preserves sharp edges
WebP	Web images (all types)	Both lossy and lossless, smallest files

Tip: For web use, WebP offers the best of both worlds — smaller files than JPEG with quality comparable to PNG. All modern browsers support it. If you need maximum compatibility, JPEG is still the safest choice.

Resizing for the Web

File size is directly related to image dimensions. A 4000×3000 photo from your phone is far larger than needed for a website, where images are typically displayed at 800-1200 pixels wide. Use the "Max Width" option to resize images during compression — this often provides the biggest savings. A 4000px image resized to 1200px at 80% quality can be 90%+ smaller than the original.

Privacy

This compressor runs entirely in your browser using the Canvas API. Your images never leave your device — nothing is uploaded to any server, stored in any database, or transmitted over the network. When you close the page, all image data is released from memory.

Frequently Asked Questions

The tool uses the Canvas API to re-encode images at your chosen quality level. For JPEG and WebP, it discards visual details the eye can't easily see. PNG is re-encoded to optimize its lossless compression.
No. Everything runs in your browser. Your images never leave your device — no uploading, no storage, no transmission. Complete privacy.
Input: JPEG, PNG, WebP, GIF, BMP. Output: JPEG, PNG, or WebP. You can convert between formats during compression — for example, convert a PNG to WebP for smaller files.
Typically 40-80% for JPEG/WebP at quality 70-80%. Combining with resizing (max width) can save 90%+. Results vary by image — photos compress better than graphics with sharp edges and text.
At 70-85% quality, most images show no visible difference. The side-by-side preview lets you compare original vs. compressed in real time so you can find the right balance.
Yes. Select multiple files or drag and drop several images at once. Each image is compressed individually and can be downloaded separately. The first image shows in the preview; all are listed below with individual download buttons.