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JPG to PDF under 400 KB

To make a PDF under 400 KB, PixelFit compresses the JPG to at most 399,262 bytes and wraps it in a one-page PDF with about 738 bytes of PDF structure, 400,000 bytes or less in total. Measured: an A4 scan at 150 DPI fits at quality 87; a 4:3 photo at about 1,427 × 1,070 pixels (quality 75).

PDF under 400 KB

PDF · under 400 KB (at most 400,000 bytes) · original pixel size · white background

PixelFit aims at 400,000 bytes or less, so the file passes whether the form counts 1 KB as 1,000 or 1,024 bytes.

Fit, background and padding white background · page the size of the picture

Saving presets is part of Pro.

Pick a photo to fit it to under 400 KB (at most 400,000 bytes).

The result appears here: the exact byte count, pixel size and quality, the size before and after, a preview and a download button.

Where the 400 KB go in a JPG-to-PDF file

Of the 400,000 bytes that pass as 400 KB under both KB definitions, PDF structure takes 738 bytes for one A4 page (computed with PixelFit's own writer), leaving 399,262 bytes, 99.8 %, for the JPEG; ten pages leave 39,475 bytes each.

For one photo, quality 75 allows 1,427 × 1,070 pixels and quality 90 1,125 × 843; a full 12 MP frame must be scaled down first, which the tool does for you.

How many pages fit in a 400 KB PDF

The 400,000 bytes of 400 KB, less 738 bytes of PDF structure for the first page and about 501 for each extra one, shared evenly.

* = extrapolated beyond our scans (3000 px long edge, 256 DPI on A4).
PagesJPEG bytes per pageMax A4 DPI at q50Max A4 DPI at q75A4 at 150 DPI
1 page 399,262 267 DPI* 197 DPI quality 87
2 pages 199,382 168 DPI 126 DPI quality 61
3 pages 132,754 127 DPI 97 DPI quality 33
5 pages 79,452 91 DPI 71 DPI no: 1.6× over at q30
10 pages 39,475 61 DPI 48 DPI no: 3.2× over at q30
20 pages 19,486 41 DPI 33 DPI no: 6.4× over at q30
50 pages 7,492 26 DPI 20 DPI no: 16.7× over at q30
100 pages 3,492 17 DPI 14 DPI no: 35.9× over at q30

Make a PDF under 400 KB →

Phone photos in one PDF under 400 KB

Largest 4:3 photo per page, in pixels, when 1 to 10 photos share 400,000 bytes; "full" means a 12 MP phone photo keeps all its pixels (the tool never enlarges).

PhotosQuality 60Quality 75Quality 90
1 photo 1,649 × 1,236 1,427 × 1,070 1,125 × 843
2 photos 1,160 × 870 1,014 × 760 797 × 597
3 photos 956 × 717 827 × 620 647 × 485
5 photos 740 × 555 639 × 479 501 × 375
10 photos 523 × 392 453 × 339 350 × 262

A4 and Letter pixel sizes against 400 KB

One typed page per DPI: its pixels, the quality it gets alone in 400 KB, and how many fit at quality 75.

DPIA4 pixelsOne A4 page under 400 KBLetter pagePages at q75
72 DPI 595 × 842 quality 95+ quality 95+ 4
100 DPI 827 × 1169 quality 95+ quality 95+ 2
150 DPI 1240 × 1754 quality 87 quality 87 1
200 DPI 1654 × 2339 quality 74 quality 75 none
300 DPI 2480 × 3508 quality 39 quality 41 none

Readable pages and photos in 400 KB

At 400 KB, 2 typed A4 pages at 150 DPI fit at quality 50 or better (1 at 200 DPI), but not one photo of 1600 × 1200 at quality 70.

One page alone gets quality 87 at 150 DPI, quality 74 at 200 DPI and quality 39 at 300 DPI.

One image free, several merged with Pro

Free: each image becomes its own one-page PDF under 400 KB. Pro: several images merged into one PDF under 400 KB, on your device; 5 pages get 79,452 bytes of JPEG each.

How to turn a JPG into a PDF under 400 KB

  1. Open the tool above

    Preset: PDF output, at most 400 KB.

  2. Add the JPG

    Drop, paste or pick it (PNG, WebP and HEIC work too).

  3. Choose the page

    Keep the picture's own size or fit it on A4 or Letter.

  4. Download

    name-400kb.pdf arrives with its exact byte count (400,000 bytes or less).

Forms with a 400 KB PDF limit

Upload specs in our dataset with a PDF limit of exactly 400 KB. Verify with the official notice before you submit.

400 KB PDF uploads

Sources

  1. Measured by PixelFit with sharp 0.35.5 / libvips 8.18.7 on 31 October 2026.
  2. Samples, Wikimedia Commons, checked 31 October 2026: typed page (public domain) commons.wikimedia.org/w/index.php?curid=194775753; landscape (CC0 1.0) commons.wikimedia.org/w/index.php?curid=154070378
  3. Paper sizes, Markus Kuhn, checked 31 October 2026: cl.cam.ac.uk/~mgk25/iso-paper.html
  4. PDF format, Library of Congress, checked 31 October 2026: loc.gov/preservation/digital/formats/fdd/fdd000474.shtml

Frequently asked questions

How do I convert a JPG to PDF under 400 KB?

Drop the JPG into the tool on this page, preset to PDF under 400 KB: the picture is compressed to 399,262 bytes or less, so the PDF ends at or below 400,000 bytes.

Can I convert JPG to PDF for free?

Yes, one image per PDF, with no upload. Under 400 KB a 4:3 photo keeps 1,427 × 1,070 pixels at quality 75; merging several JPGs is Pro.

How many pages fit in a 400 KB PDF?

About 2 typed A4 pages scanned at 150 DPI at quality 50 or better, or 1 at 200 DPI; not one photo of 1600 × 1200 at quality 70.

What DPI should a scan have for a 400 KB PDF?

For one typed A4 page, at most 267 DPI (extrapolated) at quality 50, or 197 DPI at quality 75, under 400 KB; of the usual 72 to 300 DPI settings, 200 DPI.

Why is the PDF bigger than my JPG?

A PDF wraps the JPEG in page, image and cross-reference objects: 738 bytes for one page in PixelFit's writer, about 501 more per added page.

Related

Other PDF size limits

More for 400 KB

Pixel sizes that fit 400 KB

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