Tune quality and optionally cap dimensions. Compare the new size before you download.
Image Compress redraws JPG, PNG, and WebP pictures at a quality and size you choose, then downloads the smaller files. It is meant for photos you want to email, drop into a chat, or publish on a page without shipping the full camera original. The work uses the browser canvas. The image is decoded, drawn into a bitmap of the target size with high-quality smoothing, and encoded again. QuickConvert does not upload the picture.
The quality slider runs from 10 to 100 and starts at 80. It applies to JPG and WebP. PNG is lossless, so the slider does nothing for a PNG export and is disabled when PNG is the output. The output menu defaults to Smart: a PNG is saved as JPG, and a JPG or WebP keeps its own format. You can force JPG, WebP, or PNG instead. Smart exists because a quality slider cannot shrink a PNG the way it shrinks a photo.
“Cap long edge” is on by default at 1920 pixels. Neither side of the result is allowed to exceed that number, and the aspect ratio is kept. A 4000 by 3000 photo becomes 1920 by 1440. A 1000 by 2000 portrait becomes 960 by 1920. Turn the cap off to keep the original pixel size and change only the encoding. The cap accepts a value from 64 to 8192. Each side of an image is also limited to 16,384 pixels by the encoder, and each source file must be 40 MB or smaller.
JPG output has no transparency. Transparent pixels are filled with white before the JPEG is encoded, including when Smart converts a PNG logo to JPG. If you need a transparent background, choose WebP or PNG.
One image downloads under its own name with the new extension. Several images are zipped in the browser as compressed-images.zip. After the run, the page lists each file’s size before and after, including when the result was not smaller.
Start at 80 and the 1920 cap, open the download, and only then go lower. Faces, text in a screenshot, and fine patterns show JPEG blocks before a landscape does. Screenshots of an interface often look better as PNG or as a high-quality WebP than as a low-quality JPG.
A PNG that is still large after a run was probably saved as PNG. Switch the output to JPG or WebP. The quality slider is not broken; PNG simply does not use it.
Do not upscale here. This tool only shrinks dimensions when the cap is smaller than the picture. Making a small image larger is Image Resize, and it cannot invent detail.
If you are compressing a batch, the zip is the download. Unzip it to get the individual files. The on-page list is the record of before and after sizes for that run; it is not stored after you leave the page.
“Must be a JPG, PNG, or WebP” means the file is something else, such as HEIC, GIF, or a PDF. Convert a HEIC photo with HEIC to JPG first. GIF and PDF are still outside this tool.
A file over 40 MB is rejected so the tab does not run out of memory. Resize or export a smaller copy from the camera app, then compress that.
The result is larger than the original. A PNG saved as PNG, or a JPG that was already aggressive, can grow when it is decoded and encoded again. The list says “similar size” when the new file is not smaller. Try WebP, a lower quality, or a smaller long edge. Keep the original if the new file is worse.
Transparent logos turn into white boxes on JPG. That is the format, not a failed upload. Use PNG or WebP for those files.
The browser says it could not encode the image. Canvas support is missing or the dimensions were rejected. Another current browser usually succeeds. The picture was still not uploaded.
Each image is loaded through an object URL that exists only in the page, drawn on a canvas, and released as soon as that file is encoded. The object URL is revoked in a finally block, including when encoding throws. The download URL is revoked about a second after the save. A batch zip is built in memory with JSZip and then downloaded the same way. No image bytes are posted to QuickConvert.
The public site can still record a page view with Google Analytics and may show AdSense ads on this article. Those requests do not include the picture. See the Privacy Policy and compressing images for email.
Image file size depends on two things: how many pixels there are and how the pixels are encoded. Image Compress changes both. The long-edge cap (1920 pixels by default) reduces oversized photos while keeping their shape, and the quality slider (80 by default) controls how much detail the JPG or WebP encoder keeps. Each image is decoded, redrawn, and saved in your browser, and the list shows each file’s size before and after. Your pictures are not uploaded.
A phone photo of 4000 × 3000 pixels can be 3 to 6 MB. With the default settings it becomes 1920 × 1440 and usually well under 1 MB, which still fills a laptop screen. Ten photos then fit easily in one email. The guide to compressing images for email and the web explains the controls in detail.
Application portals often want a photo under 100 or 200 KB at a fixed pixel size. Resize to the exact pixels first with Image Resize, then compress here with the long-edge cap turned off so the dimensions stay put, lowering quality in steps until the file fits. See making a photo meet portal rules.
A content column is rarely wider than 1200 to 1600 pixels. Set the cap to match your layout (double it for sharp display on high-density screens), choose WebP if your site supports it, and quality around 75 to 80.
Screenshots save as PNG, which can be several megabytes for a photo-heavy screen. Smart output converts PNG to JPG; for screenshots with lots of small text, WebP at quality 85 or higher keeps edges cleaner than JPG.
compressed-images.zip, and the list shows every file’s result.PNG is lossless, so a quality slider barely changes size. Choose JPG or WebP as the output format for a much smaller file. Transparency becomes a solid background on JPG.
A practical way to shrink photos before you attach them, including what the quality slider and long-edge cap actually do.
How JPG, PNG, and WebP differ on photos, screenshots, and transparency, and how QuickConvert treats each format.
How to tell a browser-side tool from an upload, and what QuickConvert still sends when your files stay on the device.
Job, visa, and exam portals often demand a photo of exact pixels and a maximum KB size. Here is how to crop, resize, and compress a photo to fit, step by step.