> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wipe.me/llms.txt
> Use this file to discover all available pages before exploring further.

# Image compression and the 3 MiB limit

> When Wipe.me offers local image compression and how the size budget is calculated.

Free anonymous messages are limited to a **3 MiB complete encrypted envelope**.
That limit includes more than the raw image files.

## When compression is offered

Wipe.me offers compression only when:

* the complete encrypted-envelope estimate is over 3 MiB;
* the draft contains one or more compatible static images; and
* the available budget indicates that the message can potentially fit without
  crossing the hard quality floor.

When those conditions are met, the disabled **Encrypt** action becomes **Compress
images to fit**. Selecting it opens a local estimate and confirmation dialog; the
same dialog displays progress. On success, you return to the editor and **Encrypt**
is enabled. Canceling or encountering an error leaves the draft and images unchanged.

Your original files are never modified. Only the browser draft is replaced, and only
after every selected image succeeds and the final complete envelope is verified
under 3 MiB.

## How the budget is calculated

Target allocation accounts for text, all attachments, quoted or reply blocks, and
encryption-envelope overhead—not only raw image bytes. Each compressed image has a
hard target cap of **1 MiB**. With several images, the remaining message budget is
divided dynamically.

### Standard reduction

* Images are never upscaled.
* Processing starts at up to 2560 px on the long edge.
* The quality floor is `0.72`.
* The resolution floor is 1600 px on the long edge, or the source size when smaller.

### Strong reduction

If any target falls below 250 KiB, Wipe.me shows an explicit quality warning:

* the quality floor becomes `0.60`; and
* the resolution floor becomes 1280 px on the long edge, or the source size when
  smaller.

The absolute planning floor is **96 KiB per reducible image**. If the envelope budget
would require less, compression is not offered. If the browser encoder cannot meet
the target above the applicable quality and resolution floors, the operation fails
safely and the draft stays unchanged.

## Compatible images

Compatible sources currently include browser-decodable JPEG, PNG, WebP, AVIF, BMP,
and HEIC/HEIF. Animated GIF and SVG are excluded. Output is JPEG, and transparency
is flattened onto white.

HEIC, HEIF, and AVIF codec availability depends on the browser and operating system.

<Note>
  The displayed post-compression size is an estimate. Wipe.me measures the final,
  complete encrypted envelope again before accepting the new draft.
</Note>

<Card title="Attachment metadata and privacy" icon="shield" href="/basics/attachment-metadata-and-privacy">
  See which metadata is removed from supported attachment formats before encryption.
</Card>