File too large to upload?

Whether you are emailing a scan, sharing an invoice or using an upload form, start with the format and size you need. Compression can save space, but the details still need to be readable.

Check what the upload form means

“File too large”, “maximum file size exceeded” and “attachment too big” usually refer to a size limit. Check whether it applies to one file or all attachments together. If the form says the file type is unsupported, a smaller file alone will not fix that: check the accepted formats. For a generic upload failure, also check the connection and whether your sign-in session expired.

Choose the right size

1. Keep your original. Use a scanned copy without a digital signature.
2. Choose one file. StysloDoc accepts JPG, PNG, HEIC/HEIF and PDF files up to 40 MiB. PDF compression supports up to 100 pages, subject to available device memory.
3. Set the limit. Choose a preset such as 1 MB or 4 MB, or enter a custom size from 0.05 to 20 MB and switch to KB if needed. The limit is for the whole file, including every PDF page.
4. Compress and inspect. Open the result, zoom in on small text and check every page.
5. Save a copy. You can then attach or share it yourself.

In the size selector, 1 MB means 1,000,000 bytes and 1 KB means 1,000 bytes. The input limit of 40 MiB is 41,943,040 bytes. Some apps use different units when displaying sizes; check the actual limit where you intend to use the file.

JPG and PNG images

An image that needs compression is saved as JPG. Transparent areas of a PNG become white. Compression may reduce quality, so PNG is not always the best input for artwork that needs transparency or perfectly sharp edges. If your file already meets the limit, you can keep it unchanged.

For document photos, use even lighting, keep the page flat and hold the camera straight. Crop unnecessary surroundings before choosing the file, but keep all meaningful text and edges. A smaller blurry scan is still blurry.

HEIC and HEIF photos

Photos from a phone may use HEIC or HEIF, which some forms do not accept. StysloDoc converts supported single-image HEIC/HEIF files to JPG locally, even when the original is already small. The JPG may be larger than the original; the result shows its actual size and whether it meets your limit. Image collections and sequences are rejected rather than dropping their other images. Check the displayed orientation and details before sharing.

PDF files

PDF stays PDF, with its pages in the same order and one output file. When compression is needed, pages become images: searchable text, interactive fields and digital signatures are not preserved. Use this option for scans only, and keep digitally signed originals unchanged.

Long PDFs take longer to process and may need more memory. The page limit is a processing safeguard, not a guarantee that every 100-page document will work on every phone. This tool does not split or merge PDFs.

Check the result before sharing

• Zoom in on small letters, reference numbers, stamps and signatures.
• For a PDF, check the first and last pages and the pages with the smallest text.
• Compare the copy with the original if anything looks faint, cropped or unclear.