Image too large to upload? Check size, format and pixels

Step by step

1. Open the upload-requirements mode and select an image or use the synthetic example.
2. Enter the permitted format and maximum bytes. Pasted requirements are only suggestions until you review and apply them.
3. Add maximum width and height when the form specifies them. Choose an aspect ratio only when it is actually required.
4. Run the conversion and compare the original with the exported pixels. Check small lettering, fine lines and any added canvas space.
5. Download only a result marked as meeting the supported requirements, then try it in the receiving form.

KB is not always KiB

200 KB means 200,000 bytes here. 200 KiB means 204,800 bytes. The workspace displays the exact byte limit, so you do not have to infer acceptance from a rounded size label. A receiving site may apply an additional rule that this tool does not know.

Pixel width and height are separate from compressed bytes. A highly detailed small image may weigh more than a much larger plain image. Changing a filename extension does not change the encoded format.

Preserve the content, review the compromise

The image workflow scales proportionally. An explicitly chosen different aspect ratio adds canvas space rather than silently cutting away the edges. JPEG uses an opaque background; a format change can therefore affect transparency.

The search tries a bounded set of encoder qualities and, when allowed, smaller dimensions. It does not claim to find a mathematical optimum. A passing file can still be too soft for your purpose. Your visual review matters as well as the byte check.

An impossible limit is a useful result

A one-byte target cannot hold a usable JPEG. A bounded search can stop without producing a file that meets the chosen constraints. Increase an impossible limit or review the permitted dimensions, then try again. The quality-only compression mode remains available.

Different browser encoders can produce different byte sizes. Use the numbers shown by your own run and inspect the actual downloaded image; a previous example's size is not a promise for your file.

Repeat the exercise without a private photo

Use upload-example.png, the synthetic 960 × 640 image in the workflow training ZIP linked below. Set JPEG, 200 KB, maximum 800 × 600 pixels and ratio 4:3. Allow smaller dimensions. The image is fitted without cropping, with white padding where needed.

A passing download must decode as JPEG, contain at most 200,000 bytes, keep a 4:3 aspect ratio and fit within 800 × 600 pixels. Inspect the lettering and added canvas as well. Exact output bytes are deliberately unspecified because encoders differ. An unsuccessful search must show its reason and must not offer a passing download.

What is checked

The generated bytes are decoded again and checked against the supported format, dimensions, ratio and byte requirements. This checks the produced image, not the receiving service's undisclosed policies. Inputs are bounded to 10 MiB, 20 megapixels and 8,192 pixels per side.

Processing takes place in the private workspace. Opening it from this guide loads a separate document without advertising scripts. The separate PDF byte-limit mode rebuilds all pages as JPEG images after confirmation. In its two-page synthetic test, 3,242,478 source bytes became 170,394 bytes under a 200 KB target. Both 600 × 450 point pages remained. Searchable text and vector detail were deliberately lost; do not use this mode when those features are required.

Further reading

• Download synthetic workflow training ZIP — examples, expected results and usage terms