Image Compression & File Size Guides

A deck or document full of phone photos gets huge fast. Here is how Office's Compress Pictures works on Windows and Mac, and when to shrink the photos before they go in.

A one-click tool gets you under 50KB. But 50KB means two different numbers depending on who counts, and a form that counts the smaller one can still reject the file.

200KB is the most generous of the common upload caps, so it is the one where a scanned certificate or ID keeps its fine text. Here is what to expect.

100KB is a common upload cap on job and exam portals. A dedicated one-click tool aims for it with no settings to touch — here is what to expect from your photo at that size.

Most email services cap attachments at 25MB, and encoding overhead trims that further. Here's how to shrink a photo to send it as a real attachment, and how small to actually aim.

2MB is a common upload cap and a loose target. Most photos hit it with quality alone, and files already under it are handed back untouched. Here's how, and when it gets harder.

20KB is smaller than any one-click preset, so the tool has to shrink your photo's dimensions to get there. Here's how to hit it and keep it sharp.

1MB is a generous target: you usually keep full resolution and barely lose sharpness. Here's how to hit it, and when it gets harder.

A few seconds of animation can outweigh a whole page of photos. Here's how to get it under control.

Application forms and portals love strict limits like 50KB or 100KB. Here's the fastest way to actually hit them.

PNGs get heavy fast. Here's how to shrink one without wrecking the transparency or the crisp edges you kept it for.

JPG compression is invisible until suddenly it isn't. Here's where the line sits and how to stay on the right side of it.

One kind of compression is reversible and one isn't. Knowing which you're using decides whether you can edit a file again later without watching it fall apart.

The reason a photo you keep editing and re-saving slowly turns to mush — a photocopy-of-a-photocopy effect built into how JPG works.

One kind of compression gives every pixel back exactly. The other throws some away for good. Knowing which you're using decides what you can undo.

Usually it's one of four things, and the first one accounts for most of it. Here's how to diagnose it in ten seconds.