How to compress images for email and the web

A phone photo is often several thousand pixels on the long side and several megabytes. That is a reasonable archive of a moment and a poor email attachment. Many mail systems limit a single message to around 20–25 MB, and a thread with a handful of camera originals hits that limit before the message leaves the outbox. A web page has a similar problem for a different reason: a visitor should not download a 4000 pixel photo into a 800 pixel column.

You do not need a smaller copy of every photo you take. You need a smaller copy of the ones you are about to send or publish. Keep the camera file. Make the delivery file with Image Compress.

The tool decodes JPG, PNG, or WebP in the browser and draws the picture onto a canvas with high-quality smoothing, then encodes it again. Two choices do almost all of the work: the long-edge cap, and the format plus quality.

The long-edge cap is on by default at 1920 pixels. Neither side of the result is longer than that number, and the shape is preserved. A 4000 by 3000 landscape becomes 1920 by 1440. A tall 1000 by 2000 picture becomes 960 by 1920, because the long side is the height. Turn the cap off only when you must keep the original pixel count and you are willing to rely on encoding alone. The field accepts 64 to 8192. There is a separate hard stop at 16,384 pixels per side in the encoder, and each source file must be 40 MB or under.

Quality runs from 10 to 100 and starts at 80. It applies to JPG and WebP. PNG ignores it, and the slider is disabled when the output is PNG, because PNG is lossless. Eighty is a sane place for a photo that should still look like a photo at normal viewing size. If you can see blocks, or halos around text in a screenshot, raise the quality or change the format. If the file is still too big and the picture looks clean, lower the long edge before you destroy the quality. Dimensions are usually the larger lever.

The output menu defaults to Smart. A PNG is saved as JPG. A JPG stays JPG. A WebP stays WebP. Smart is there because people export photos as PNG, then wonder why a quality slider does nothing. You can force JPG, WebP, or PNG. Forcing PNG is how you keep a lossless graphic, and it is how you fail to shrink a photograph.

JPG fills transparency with white. A logo with a clear background will sit on a white rectangle. If the image needs a clear background, choose PNG or WebP instead of Smart.

1. Drop the photos on Image Compress. A batch is fine. One image downloads under its own name. Several images download as compressed-images.zip, zipped in the browser.
2. Leave Smart, quality 80, and the 1920 cap for ordinary photos.
3. Download, open one or two of the results at the size you will actually view, and check faces and any small text.
4. If a file in the on-page list did not get smaller, it was already efficient or you exported PNG as PNG. Switch that one to WebP or JPG and run it again from the original.
5. Rename nothing important over the camera original. The download is a new file.

Screenshots are the exception. A picture of a software window has hard edges and text. JPEG at 80 can look cheap. Try PNG if the screenshot is already small, or WebP at a high quality, and cap the long edge to the width you need rather than to 1920 if the shot is only going in a document at half that size.

For a website, 1920 on the long edge is plenty for a full-width photo on a normal desktop and too big for a thumbnail. Resize the thumbnail to the display size with Image Resize instead of asking every visitor to download the hero and then shrinking it in CSS. CSS changes how it is drawn. It does not change how many bytes were transferred.

HEIC is not accepted by Image Compress. Convert it with HEIC to JPG, then compress that JPG if it is still large. A file over 40 MB is rejected so the tab does not die on a giant decode. Export a smaller copy from the camera roll first.

A result that is larger than the source is possible. Decoding a tight JPG and encoding it again, or saving a PNG as PNG, can grow the file. The list under the button says when the new size is not smaller. Keep the original in that case. Try a smaller long edge or WebP rather than running the same settings again and hoping.

GIF, AVIF, and PDF are out of scope. A picture that lives inside a PDF is a job for PDF Compress, which re-encodes embedded images and leaves real text as text.

The pictures are processed on the device. The page does not post them to QuickConvert. A zip of a batch is built in memory and then saved by the browser. Close the tab and the working copies are gone. What the site itself may still record — a page view, an ad — is described in the Privacy Policy and in privacy with online file tools. Format choices are compared in JPG vs PNG vs WebP.