Frequently Asked Questions

Everything you need to know about compressing images online with Bulk Image Compressor: the free tool for batch compressing JPEG, PNG, WebP, and AVIF files directly in your browser.

How do I compress multiple images at once?

Drag and drop your images onto the tool (or click to browse), choose an output format and quality level, then press Compress. Every image is processed in a batch and you can download them all together as a single ZIP file, or grab individual files one by one.

Are my images uploaded to a server?

No. Bulk Image Compressor runs entirely in your browser using WebAssembly. Your photos never leave your device, which makes it safe to compress private documents, ID scans, or client work. It also means compression starts instantly with no upload wait.

Which format should I choose: WebP, AVIF, JPEG, or PNG?

WebP is the best all-rounder: 25 to 35 percent smaller than JPEG at the same visual quality, and supported by every modern browser. AVIF compresses even harder and is great for web publishing, but encoding is slower. Choose JPEG when you need maximum compatibility with older software, and PNG when you need lossless quality or transparency.

How can I reduce image file size without losing quality?

For photos, a quality setting of 75 to 85 in WebP or JPEG is visually indistinguishable from the original for most images while cutting file size dramatically. For graphics, logos, and screenshots, use PNG with lossless optimization, or enable color quantization to shrink PNGs further with virtually no visible difference. Use the built-in before/after slider to verify quality before downloading.

Is there a limit on how many images I can compress?

There is no artificial limit on the number of images or their file size. Because processing happens on your own device, the practical limit is your computer’s memory. Batches of hundreds of photos work fine on a typical laptop.

Can I resize images while compressing them?

Yes. Enable the resize option and set a target width or height, or pick a percentage preset. Several scaling methods are available, including Lanczos for sharp photographic downscaling and pixelated mode for pixel art. Resizing before compression is the single most effective way to cut file size for web use.

Is Bulk Image Compressor really free?

Yes, completely free with no account, no watermarks, and no daily limits. The site is supported by ads.