The USPTO Patent Center PDF requirements that stop uploads are a size cap and a few format rules: each PDF may not exceed 25 MB, a submission holds up to 100 documents, and every PDF needs a document description. This page covers each rule with its source, which files you can shrink, and which you should not. It is not legal advice.
| What you are sending | The limit you hit | The Smol setting |
|---|---|---|
| Scanned office action response, exhibits or declaration | 25 MB per PDF in Patent Center | PDF preset Medium (Small if it is still over; check text stays readable) |
| Cited non-patent literature, large prior art bundles | 25 MB per PDF; 100 documents per submission | Medium for scans, Small for text pages; check legibility |
| Specification and claims exported as PDF | 25 MB per PDF; one document description per part | Often under the cap already. Try Large only if needed |
| Patent drawings as PDF | Black lines, margins and 1/8 inch characters under 37 CFR 1.84 | Do not compress. Split or re-export from the source instead |
What are the USPTO Patent Center PDF requirements?
Patent Center accepts PDF, DOCX, TXT, XML and PCT zip files, caps each PDF at 25 MB, and allows 100 documents per submission. The table lists each rule with the USPTO page it comes from.
| Rule | Figure | Source |
|---|---|---|
| Largest PDF | 25 MB per document | Patent Center User Guide |
| Largest DOCX | 10 MB per document | Patent Center User Guide |
| Documents per submission | 100 | Patent Center User Guide |
| File name | Up to 100 characters including extension; lowercase .pdf; start with a letter or digit | USPTO file naming |
| Multi-document PDF | Each part must be separately indexed with its document description and pages | Patent Center User Guide |
The user guide also says that not all PDF files are the same and urges filers to review the USPTO’s PDF Guidelines. Read those and your own practice resources before you file; they are the final word, not this page.
What is the Patent Center file size limit, and what happens above it?
The Patent Center file size limit is 25 MB for a PDF and 10 MB for a DOCX. A larger file fails validation and cannot be submitted until you replace it. Documents over the cap cannot be validated.
The user guide lists the validation errors: a file that is not one of the allowed types, a PDF over 25 MB, a DOCX over 10 MB, a sequence listing over its limit, and a missing document description. So “uspto pdf rejected” usually comes down to one of those, so check the file name against the naming rules above as well.
Two ways under the cap
- Make the PDF smaller. This works for scans and for PDFs made from large images, as in the rest of this page.
- Split it into several documents. Patent Center lets one submission hold 100, each with its own document description. If a bundle is one logical item, ask your practice team how to describe the parts.
How should patent drawings be saved as a PDF?
Drawings must follow 37 CFR 1.84: A4 or 8.5 × 11 inch sheets, black and white by default, lines that are “durable, clean, black” (except color drawings) and dense, and characters at least 1/8 inch (.32 cm) high. Export them from the drawing source rather than recompressing.
| Rule | What it says | Why it matters for a PDF |
|---|---|---|
| Sheet size | 21.0 × 29.7 cm (A4) or 21.6 × 27.9 cm (8.5 × 11 in); all sheets the same size | Export every sheet at one size |
| Margins | At least 2.5 cm top, 2.5 cm left, 1.5 cm right, 1.0 cm bottom | Resizing a page can shift content into a margin |
| Characters | Numbers, letters and reference characters at least .32 cm (1/8 in) high | Shrinking pages shrinks the numerals too |
| Line quality | Durable, clean, black, sufficiently dense and dark, uniformly thick and well-defined | Lossy compression softens thin lines |
| Color | Black by default; the Office accepts color drawings in utility applications only after granting a petition | Do not send color unless you filed the petition |
| Photographs | Not ordinarily permitted; accepted if they are the only practicable medium | Check before attaching one |
The rules are in the current text of 37 CFR 1.84, Read it in full before filing, since this table is a summary.
Which Smol settings compress a PDF for USPTO upload?
Choose Medium for scanned exhibits and Small if the file is still over 25 MB. Presets are pixel caps on page images, not DPI targets, so the resulting resolution depends on page size. Smol sets quality and pixel size, not output bytes, so check the size of the result.
| Preset | Long-edge pixel cap | JPEG quality (approx.) | Starting point for |
|---|---|---|---|
| Tiny | 600 px | 25 | Never for legal text; unreadable on scans |
| Small | 900 px | 45 | Large bundles of typed references |
| Medium | 1200 px | 60 | Scanned declarations and exhibits |
| Large | 1800 px | 75 | Scans with fine print or stamps |
| Original | 2400 px | 88 | Not lossless; it resamples above 2,400 px |
The “starting point” column is our suggestion, not a USPTO standard. In our scanned-PDF test, a 3-page agreement scanned at 300 PPI came out at about 109 PPI on Medium, 82 on Small and 55 on Tiny. A separate OCR tool recovered all the words on Medium and 96.8% on Small, but only 1.42% on Tiny. Those are the numbers from that post, from one scan, so read them as a warning about Tiny, not as a promise for your file. For the same reason, open every output and read it before you file.
Smol does not edit, merge, split or OCR a PDF, and it does not redact. If a bundle needs splitting or a text layer, do that first with another tool. The same post tested a separate OCR step and then Smol Medium: it took one 5,017,560-byte scan to 288,609 bytes (94.2% smaller) with the text layer intact.
How do you compress a PDF for USPTO on a Mac?
Drop the PDF into Smol, pick a preset, compress, and open the copy to read it before you upload. The original stays beside it by default, so you can always file the larger one in pieces instead.
Check the size and type
Select the file in Finder and look at its size. Anything under 25 MB needs no compression for Patent Center. Leave drawing sheets out of the batch.
Drop the PDF into Smol
Drag in one file or a whole folder of exhibits. Smol writes a copy with a
_compressedsuffix and leaves the original untouched by default.Choose Medium, then compress
Start at Medium for scans. Use Small only if the result is still over the cap.
Read the output and check the size
Page through the copy at actual size. Check signatures, stamps, footnotes and any numbers. If it is over 25 MB, go one preset down or split the document.
Name it to the USPTO rules
Rename the file so it starts with a letter or digit, ends in lowercase
.pdf, and stays within 100 characters, then upload it.
Unpublished claims, inventor declarations and office correspondence are confidential until you choose to file them. Smol runs on your Mac and uploads nothing, so the compression step does not send a file to anyone. For the wider workflow, see compressing documents for legal filing and our guide to batch compressing PDFs.
What do patent filers use today to shrink a PDF?
Start with whatever is built in: Preview, Acrobat, or the scanner’s own settings. Each works for some files and not others, so test on a copy of yours.
| Option | Cost | Where it works | Where it falls short |
|---|---|---|---|
| Re-scan at lower resolution or black and white | Free | Scanned exhibits: fixes the size before the PDF exists | Needs the paper; text can degrade if set too low |
| Split into several documents | Free | Bundles: stays under 25 MB without touching quality | Needs correct document descriptions for each part |
| Preview “Reduce File Size” | Free, built in | Image-heavy scans | Can enlarge text PDFs: it took a 21-page contract to 111.8% in our test |
| Adobe Acrobat optimizer | Paid | Fine control over images and fonts | Needs a paid Adobe plan; more settings to learn |
| Smol | $29 once | Scanned and image-heavy PDFs, in batches, offline | Presets only; no OCR, redaction, merge or split |
If you only need an occasional shrink, the free methods we tested may be enough. If you compress PDFs weekly and do not want Acrobat, see our Acrobat alternatives. Teams that file in volume can see Smol for law firms and drawing PDFs.
For firms: pricing and presets
Solo is $29 once for one Mac. Team is $49 once for three Macs, and Enterprise is $20 a seat for 5 to 500 seats. Presets are saved on each Mac and are not shared between machines, so a firm should write down its preset and recreate it on every Mac. See pricing.
When is Smol the wrong tool for a patent filing?
Smol is the wrong tool for drawings, for anything you must keep exactly as created, and for edits to the PDF itself. It re-encodes pages, and it is not an editing suite.
- Patent drawings, for the reasons in the drawings section. Re-export them from the source file.
- Files that are already under 25 MB. They gain nothing from compression and may lose sharpness.
- PDFs from generators that barely shrink. Some, such as ReportLab output, compress by almost nothing.
- Redaction. Smol does not redact, so use a tool built for it before you compress.
- A PDF that needs merging, splitting, OCR or signing. Smol does none of these. Compress before signing, not after.
- Files you must prove unchanged. Even the Original preset is not lossless.
Frequently asked questions
What is the Patent Center file size limit?
Patent Center allows 25 MB per PDF and 10 MB per DOCX, and up to 100 documents per submission, per the USPTO’s September 2025 user guide. A file over its limit fails validation, so the document cannot be submitted until you replace it with a smaller file or split it into parts.
Why was my PDF rejected by the USPTO?
The user guide lists these validation errors: a file that is not a DOCX, PDF, TXT, XML or PCT zip, a PDF over 25 MB, a DOCX over 10 MB, a sequence listing over its limit, or a missing document description. Check those first, then check the file name against the USPTO naming rules.
How do I compress a PDF for USPTO on a Mac?
Check the size first. If it is over 25 MB and is a scan or image-heavy file, drop it into Smol, choose Medium, and compress. Open the copy and read it at actual size, then check its size again. If it is still over, try Small or split the document. Smol keeps the original beside the copy by default.
Can I compress a patent drawings PDF?
We advise against it. Rule 37 CFR 1.84 requires clean, dense black lines and characters at least 1/8 inch high, and lossy compression can soften both. Smol’s presets re-encode and resample page images, and Original is not lossless. Re-export drawings from the source file instead, and use the rule text, not this page, as your standard.
What are the USPTO Patent Center PDF requirements for drawings?
Drawings follow 37 CFR 1.84: sheets are A4 or 8.5 x 11 inches, all one size, with margins of at least 2.5 cm top and left, 1.5 cm right and 1.0 cm bottom. Lines must be durable, clean and black, and characters at least .32 cm high. Check the rule text before filing.
Does compressing a PDF remove its metadata?
Not in the PDF presets. No Smol PDF preset strips metadata, so use the separate strip-metadata operation if you need to clear document properties. Our post on removing PDF metadata explains that cleared properties can be recoverable unless the file is rewritten, so do not rely on it as a guarantee.
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