# I'm stuck - how to reduce size of PDF on mobile? **URL:** \ **Category:** Signing on the Go\ **Tags:** paperless\ **Created:** [October 29, 2026, 3:05pm UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50 "2026-10-29T15:05:13Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![catherine1997](https://altosignpdf.com/community/letter_avatar_proxy/v4/letter/c/e9bcb4/32.png) [@catherine1997](https://altosignpdf.com/community/u/catherine1997)\ **Post date:** [October 29, 2026, 3:05pm UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/1 "2026-10-29T15:05:13Z")
Ok so I’ve got a 30-page scanned form that I need to send through an online portal, but it’s over the 10 MB limit by a lot. I’m on my phone right now and don’t have a computer nearby, and I’m honestly not sure what my options are for shrinking it down before my deadline tonight. ---
**Author:** ![someone73063](https://altosignpdf.com/community/user_avatar/altosignpdf.com/someone73063/32/21_2.png) [@someone73063](https://altosignpdf.com/community/u/someone73063)\ **Post date:** [October 29, 2026, 3:05pm UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/2 "2026-10-29T15:05:15Z")
That’s annoying, especially with a deadline. On your phone, try a PDF compressor app or a browser-based compressor, then choose medium compression first so the form stays readable. If it’s still too large, scan again at 150 dpi or in greyscale rather than colour, which usually makes the biggest difference for 30 scanned pages. ---
**Author:** ![noobPhantom07](https://altosignpdf.com/community/user_avatar/altosignpdf.com/noobphantom07/32/22_2.png) [@noobPhantom07](https://altosignpdf.com/community/u/noobPhantom07)\ **Post date:** [October 30, 2026, 8:08am UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/3 "2026-10-30T08:08:47Z")
Had the same issue last month with field forms over the portal limit. I used the Adobe Acrobat app on my phone, opened the file and chose reduce file size, which compressed the scans enough to get under 10 MB. If that’s not on your phone, search PDF compressor in the browser and try one, but I’m not sure which is best. ---
**Author:** ![nicholasb23](https://altosignpdf.com/community/user_avatar/altosignpdf.com/nicholasb23/32/31_2.png) [@nicholasb23](https://altosignpdf.com/community/u/nicholasb23)\ **Post date:** [October 30, 2026, 5:23pm UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/4 "2026-10-30T17:23:19Z")
I’ve been there with a deadline. What I do now is rescan the pages with my phone’s built-in document scanner, set to black and white and lower resolution, then save that as the PDF. Text scans shrink a lot that way and usually get under a 10 MB limit. ---
**Author:** ![henry2010](https://altosignpdf.com/community/user_avatar/altosignpdf.com/henry2010/32/24_2.png) [@henry2010](https://altosignpdf.com/community/u/henry2010)\ **Post date:** [November 1, 2026, 12:08am UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/5 "2026-11-01T00:08:21Z")
Scanned forms always end up massive, especially on a mobile. I use PDFcap for this when I’m out on a building site and need to send estimates. Just open [pdfcap.com](http://pdfcap.com) in your browser, upload the document, and choose the compress tool to shrink it down. It usually gets my contracts well under the limit. Did that manage to sort it out for you? ---
**Author:** ![jennifer.08](https://altosignpdf.com/community/user_avatar/altosignpdf.com/jennifer.08/32/32_2.png) [@jennifer.08](https://altosignpdf.com/community/u/jennifer.08)\ **Post date:** [November 2, 2026, 5:38am UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/6 "2026-11-02T05:38:15Z")
[nicholasb23](https://altosignpdf.com/community/u/nicholasb23) That’s what I do at the library desk too, the black and white scan trick is a lifesaver. One tip: check the file size after page one before you scan all 30 again, saves you redoing it. Just avoid cranking the resolution too low, I learned the hard way that blurry signatures can get rejected by strict portals. ---
**Author:** ![shy\_pal](https://altosignpdf.com/community/user_avatar/altosignpdf.com/shy_pal/32/33_2.png) [@shy\_pal](https://altosignpdf.com/community/u/shy_pal)\ **Post date:** [November 3, 2026, 10:53am UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/7 "2026-11-03T10:53:27Z")
first check whether the portal needs all 30 pages. if it does, try rescan the paper at 150 dpi in grayscale using Drive’s scan mode or iPhone Notes, then save it as PDF. if you already have the scan, open it in your browser and try Print \> Save as PDF at a lower scale. check the file size before uploading and keep it below 10 MB. ---
**Author:** ![hunter99](https://altosignpdf.com/community/user_avatar/altosignpdf.com/hunter99/32/34_2.png) [@hunter99](https://altosignpdf.com/community/u/hunter99)\ **Post date:** [November 4, 2026, 11:23pm UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/8 "2026-11-04T23:23:13Z")
Scanned pages are usually the problem, too high resolution. Try AltoSignPDF’s compress tool on your phone, pick the “smaller size” option, should get it well under 10MB fast. Keep the original scan saved somewhere too, just in case you need full quality later. ---
**Author:** ![mia\_cork](https://altosignpdf.com/community/user_avatar/altosignpdf.com/mia_cork/32/35_2.png) [@mia\_cork](https://altosignpdf.com/community/u/mia_cork)\ **Post date:** [November 6, 2026, 10:53pm UTC](https://altosignpdf.com/community/t/im-stuck-how-to-reduce-size-of-pdf-on-mobile/50/9 "2026-11-06T22:53:23Z")
@[shy\_pal](https://altosignpdf.com/community/u/shy_pal) That first question is the one I’d ask too, half the forms I submit have cover pages the portal doesn’t want. One caution from my own grant reports: Print then Save as PDF can flatten any fillable fields, so check the form still accepts typing before you upload. If it does, greyscale at 150 dpi on 30 pages usually lands well under 10 MB for me.