Bulk Image Compressor — Compress Many Images at Once

Guide: compressing a whole batch of images at once

What each preset actually changes

The three presets set the encoder quality used for every file: High Quality uses 0.92, Balanced (the default) uses 0.8, and Max Compression uses 0.6. When you click Compress all, each image is drawn at its original pixel size and saved again in its own format, one file after another. You can add up to 100 PNG, JPG or WEBP files per batch; anything beyond that is skipped with a message.

Each row shows the new size and the percentage saved, and a summary gives the total. The results are packed into compressed-images.zip, with every file named after the original plus -compressed, such as photo-compressed.jpg. The ZIP packager loads only when you compress, and nothing is uploaded.

Before you start, you can remove any file with the cross on its row, add more files at the end with Add more, or begin again with Clear all.

JPG, WEBP and PNG behave differently

The quality setting applies to JPG and WEBP, which is where the savings come from. PNG is a lossless format, and browsers ignore the quality setting when saving PNG, so all three presets give the same PNG result, which can be about the same size as the original or even larger. In that case the row shows "saved 0%", but the re-saved file is still placed in the ZIP. For PNG photos, convert them with PNG to JPG first; for PNG screenshots and graphics, keeping the original is often the better choice.

Dimensions stay the same

Bulk compression does not resize. A 4000 by 3000 phone photo is still 4000 by 3000 afterwards. For websites and catalogues, the biggest reduction often comes from making images smaller in pixels, which you can do one at a time with the Image Resizer. When a single file must be under a strict limit, such as a 50 KB exam photo, use Compress to Size or Compress to 50 KB, which search for the right quality for that file, rather than applying one fixed quality to everything.

Who it helps

• Sellers preparing a set of product photos for a WhatsApp Business catalogue or their own website.
• Office staff shrinking site-inspection or event photos before attaching them to a report or email.
• Teachers and students sharing class event photos through email or a shared drive.
• Bloggers reducing a post's images before uploading them to a CMS.
• Families emailing a set of wedding or trip photos to relatives, where attachment size limits apply.

A sensible workflow

• Start with Balanced.
• Open a few files from the ZIP at full size, especially ones with faces or text.
• If you see blocky edges or smudged text, clear the list and run the batch again with High Quality.
• Keep Max Compression for previews, thumbnails and images that will be shown small.
• Remember the ZIP is a copy; your original files are unchanged on your device.
• On a phone, work in smaller batches, since every file is processed on the device.

Common mistakes

• Compressing images that were already compressed, such as photos saved from WhatsApp, again and again. Each round loses a little more detail.
• Expecting PNG screenshots to shrink.
• Using Max Compression on documents or images with small print.
• Uploading HEIC files; convert them with HEIC to JPG first.

Related guides

• How to Compress Images Without Losing Quality (and Reduce Size in KB)
• Image Optimization for Websites: Formats, Sizing, Lazy Loading and Caching
• PNG vs JPG vs WebP vs AVIF: Which Image Format Should You Use?