Compress an image to an exact file size

Why your image is too big

Phone cameras have improved far faster than upload limits have. A photo from a recent iPhone or Pixel runs 3 to 8MB straight out of the camera, and a scanned document can be larger still. Meanwhile the form you are trying to submit was probably built years ago against a 2MB ceiling that nobody has revisited since.

Common upload limits

How to hit a size limit without wrecking the image

Reduce the pixel dimensions before you reduce quality. An 8000-pixel-wide photo squeezed to 200KB will look smeared, because the encoder is trying to describe far too much detail in far too little space. That same photo resized to 1920 pixels wide first will hit 200KB looking clean.

As a rule: 1920 pixels on the longest side is plenty for anything viewed on a screen, and 1080 is fine for most application forms and profile photos.

Related things people need

If your photos came off an iPhone and will not open on Windows, they are in HEIC format and need converting to JPG before anything else will accept them.

If a form wants one PDF rather than several images, merge them into a document instead of compressing each one. And if you simply need a different file type, the format converter handles JPG, PNG and WebP.

What compression actually removes

JPEG compression works by exploiting the gap between what a camera records and what a person can perceive. It divides the image into small blocks, describes each block as a set of frequency patterns, and then discards the patterns contributing least to what the eye notices — mostly fine colour variation, which human vision is far less sensitive to than brightness.

At quality 90 the discarded information is genuinely imperceptible. At 70 it is invisible in normal viewing but detectable if you compare side by side. Below about 50, characteristic artefacts appear: faint blocky squares in areas of flat colour, and a soft halo around sharp edges, most obvious around text.

This is why the same quality setting produces different results on different images. A portrait with soft backgrounds tolerates heavy compression well. A screenshot of a spreadsheet does not, because it is nothing but sharp edges.

Dimensions matter more than quality

The single most common mistake is compressing hard while leaving the image at full resolution. A 6000-pixel-wide photograph squeezed to 200KB has to describe 24 million pixels in very little space, and the encoder has no choice but to discard aggressively. The same photograph resized to 1500 pixels first has only 1.5 million pixels to describe, and 200KB is comfortable.

The practical guidance is straightforward. For viewing on a screen, 1920 pixels on the longest side is more than enough — larger than most laptop displays. For an application form or profile photo, 1080 is plenty. For printing at ordinary sizes, 2400 covers it. Only archival work needs the full resolution the camera produced.

When compression will not help

Some files are already as small as they are going to get, and compressing them again makes things worse rather than better.

• Images already compressed once — a photo someone sent you through a messaging app has usually been squeezed already. Compressing again adds new artefacts on top of the old ones.
• Screenshots saved as PNG — converting to JPG will often produce a larger file, not a smaller one, and will blur the text.
• Very small images — below about 100KB there is little left to remove.

When the result comes back the same size or larger, that is the tool telling you the original was already efficient. Keep it.

Metadata and what disappears

Photographs carry EXIF metadata: the camera model, exposure settings, the date and time, and often GPS coordinates recording exactly where the picture was taken. Re-encoding an image discards all of it.

That is usually welcome. Posting a photograph taken at home, complete with coordinates, is a genuine privacy problem that most people never think about. But if you rely on photo dates for sorting or records, keep your originals, because that information does not come back.

Questions

Are my images uploaded anywhere?

No. Everything happens inside your browser using your device's own processor. Nothing is sent to a server, and the tool keeps working if you disconnect from the internet after the page loads.

Why is my compressed file bigger than the original?

This happens when the original was already efficiently compressed and you asked for high quality, or when converting a small PNG graphic to JPG. Lower the quality, reduce the dimensions, or keep the original.

Does compressing remove location data?

Yes. Re-encoding drops EXIF metadata, including GPS coordinates, camera model and timestamp.