How big is 1 MB, exactly?
It depends on who is counting. Some systems take a megabyte as 1,000,000 bytes, others as 1,048,576 (1,024 x 1,024). This page aims under 1,000,000 bytes, so the copy fits either way. In the result, the size is shown in KB counted in 1,024-byte steps, which is why a file just under the target reads as about 977 KB.
What fits in 1 MB
A 1 MB limit is generous for a single document and workable for long ones. Typed documents of dozens of pages usually fit as they are. Colour scans keep good detail across several pages. PDFs with embedded photographs, such as brochures, portfolios or presentations saved as PDF, are the files most likely to be over, because each photo inside can be large.
- Presentations and brochures: pages are redrawn as pictures at the sharpest level that fits, so photos and slides keep their look.
- Scanned bundles: a set of certificates scanned into one PDF shares the 1 MB; the result shows the DPI used.
- Reports with charts: if the lossless step is enough, charts and text stay sharp and selectable.
Email and portal uploads
When a portal gives one upload slot for several documents together, the limit is often set in MB rather than KB, and a 1 MB file also keeps an email light enough to arrive on a slow connection. Before you send or upload, open the downloaded copy once: check the page count, the order and any small print, such as roll numbers and dates.
Keeping it readable
The tool chooses the highest DPI that fits with good JPG quality, rather than squeezing quality to the bottom, because blurry pages are harder to read than slightly smaller ones. For long scans of plain printed pages, black and white keeps text crisp at a much higher DPI than colour; it is not the right choice for pages with photographs.
Other sizes
With a little less room, use compress PDF to 500 KB; for larger files, compress PDF to 2 MB. Any other limit works on compress PDF.
Built on two open-source projects that run in your browser: qpdf, compiled to WebAssembly, for the lossless rewrite, and Mozilla's PDF.js to redraw pages when that is not enough.