PDF Page Size Checker

What is a PDF page size?

A PDF page size is the physical dimension of a single page in the document's coordinate system. PDFs define page dimensions in points — a unit where 1 point equals 1/72 of an inch. When a page is described as "A4", it means its dimensions are approximately 210 × 297 mm, which is the same as 595.28 × 841.89 points. Detecting whether a PDF is A4, Letter, or a custom size means measuring those point values and comparing them against known standards.

Unlike a Word document, a PDF stores an explicit page box for every page. The most important one is the MediaBox — the physical paper boundaries of the page. There's also the CropBox (the visible/printable area after cropping), the BleedBox, the TrimBox, and the ArtBox. This tool reports the MediaBox as the physical page size, because that's what determines how the document will behave when printed or rendered.

How PDF page dimensions work

Every PDF page has a coordinate system with an origin at the bottom-left (0, 0). The page's dimensions are defined by a rectangle in that coordinate system — usually starting at (0, 0) and extending to (width, height) in points. A typical A4 page is 595.28 × 841.89 points because:

210 mm ÷ 25.4 = 8.2677 inches
8.2677 in × 72 = 595.276 points

297 mm ÷ 25.4 = 11.6929 inches
11.6929 in × 72 = 841.890 points

A PDF viewer or printer converts those points to pixels or physical units for display. This tool shows you the raw point values plus the equivalent in mm, cm, and inches — the same dimensions, just expressed in the unit most useful for your workflow.

What is a PDF point?

A PDF point (pt) is the fundamental unit of the PDF coordinate system. It is not a pixel. The definition is fixed:

• 1 inch = 72 points
• 1 point = 1/72 inch = 0.3528 mm
• 1 mm = 2.8346 points

The point unit predates digital typography — it comes from traditional printing, where 72 points to the inch was the Anglo-American standard. This is why PDF libraries return page dimensions like 595.28 × 841.89 instead of "210 mm × 297 mm": the PDF spec was written before millimetres were the norm in software interfaces.

Every conversion in this tool is done from the raw point values, so unit toggling never changes the underlying measurements — only the display.

How to check a PDF page size

The workflow is simple:

1. Drop your PDF onto the upload area — or click to browse. The file is read locally.
2. The tool parses the PDF and extracts every page's MediaBox dimensions and rotation.
3. Each page is compared against a database of standard paper sizes (A-series, B-series, US Letter, Legal, Tabloid, and so on).
4. The page-by-page table shows the width, height, detected size, orientation, and rotation for every page.
5. Change the unit dropdown to see dimensions in mm, cm, inches, or points — no re-parsing happens.
6. Copy the summary or download a report as TXT, CSV, or JSON.

The PDF is never uploaded. Parsing happens entirely in your browser using a WebAssembly-accelerated JavaScript PDF parser. Closing the tab discards everything.

Common PDF paper sizes

Almost every business, academic, or government document uses one of a small set of standard page sizes. This tool detects them automatically:

• A4 — 210 × 297 mm. The default in most of the world.
• A3 — 297 × 420 mm. Twice A4 by area.
• A5 — 148 × 210 mm. Common for booklets and notebooks.
• Letter — 215.9 × 279.4 mm (8.5 × 11 in). The default in the US and Canada.
• Legal — 215.9 × 355.6 mm (8.5 × 14 in). Common for contracts.
• Tabloid — 279.4 × 431.8 mm (11 × 17 in). Tabloid newspapers and posters.
• Executive — 184.15 × 266.7 mm (7.25 × 10.5 in).
• B4, B5 — ISO B-series sizes used in printing and publishing.

If a page doesn't match any of these within the tolerance, the tool reports it as Custom — the actual measured dimensions are always shown alongside the label.

A4 vs Letter PDF size

A4 and Letter are similar but not identical, and the difference occasionally causes printing problems:

A4:     210.0 × 297.0 mm   8.27 × 11.69 in   595.28 × 841.89 pt
Letter: 215.9 × 279.4 mm   8.50 × 11.00 in   612.00 × 792.00 pt

A4 is narrower and taller than Letter. A PDF designed for A4 will scale slightly when printed on Letter paper (or vice versa), unless the printer's "fit to page" setting is disabled — in which case some content may be clipped. If you're preparing a document for a specific region, verifying the actual page size with this tool is worth the ten seconds it takes.

Portrait vs Landscape PDF pages

Orientation is derived from the dimensions, not from metadata:

• Portrait — height is greater than width (e.g. 210 × 297 mm).
• Landscape — width is greater than height (e.g. 297 × 210 mm).
• Square — width and height are equal within tolerance.

Crucially, orientation is orthogonal to paper size. An A4 landscape page is still A4 — it's the same sheet, viewed sideways. This tool reports both separately: Size: A4, Orientation: Landscape. Treating them as a single combined category would make mixed-orientation documents harder to understand.

PDF page rotation

PDF pages can carry a /Rotate entry with a value of 0, 90, 180, or 270 degrees. This tells the viewer to rotate the page when displaying or printing, without changing the underlying MediaBox dimensions. The rotation is a display property, not a measurement.

For example, a page with a MediaBox of 595.28 × 841.89 points (A4 portrait) and /Rotate 90 will display as landscape, but the physical paper is still A4 portrait — the viewer just rotates it. This tool reports the MediaBox dimensions as the page size and shows rotation separately, so you can see both facts.

PDF MediaBox and CropBox

The PDF spec defines several page boxes:

• MediaBox — the physical page boundary. This is the paper size.
• CropBox — the region the viewer should display by default. Often the same as MediaBox; sometimes smaller when a document has been cropped.
• BleedBox, TrimBox, ArtBox — additional print-production boxes.

The physical page size is the MediaBox. That's what this tool reports, because it's what determines how the document fits on paper. If a PDF was cropped (for example, a scanned document where the scanner's edge was trimmed), the CropBox may be smaller than the MediaBox — but the paper the document was created for is still the MediaBox size.

How to detect mixed PDF page sizes

Not every PDF is uniform. A report might have A4 pages followed by an A3 fold-out; a manuscript might be Letter throughout except for a landscape table. This tool detects mixed-size documents by:

1. Reading the MediaBox of every page.
2. Normalizing each to (shorter side, longer side) so orientation doesn't matter for grouping.
3. Comparing each page against every other page with a tolerance of ~0.5 mm.
4. Grouping pages that match and reporting the ranges.

The result is a summary like:

A4 Portrait      Pages 1–20
A4 Landscape     Pages 21–22
A3 Landscape     Pages 23–24

Each group is listed with its page range, so you can see exactly which pages differ. A mixed-size PDF is often a sign of a PDF-generation bug, a manual edit that didn't propagate, or a hybrid document. The tool tells you where the differences are.

PDF page size vs DPI

These are frequently confused. Page size (A4, Letter) is a physical dimension — how big the sheet of paper is. DPI (dots per inch) describes how many pixels an embedded raster image contains per inch of that sheet. A PDF can have A4 pages containing images at 72 DPI (screen quality), 300 DPI (print quality), or 1200 DPI (high-end print). The page size is the same in all three cases; only the image resolution differs.

This tool measures page size, not image DPI. Detecting the effective DPI of an image inside a PDF requires analyzing each XObject's pixel dimensions and its placement on the page — a separate operation that this tool does not perform.

PDF page size vs file size

Also unrelated: a PDF can have A4 pages and be 40 KB or 400 MB. The file size depends on images, fonts, embedded resources, and compression. A text-only invoice with the same dimensions as a photography portfolio will be thousands of times smaller. Use the Hash Generator if you also need to verify a file's integrity, and use this tool if you need to verify its page geometry.

How developers use PDF page size checking

• Validate generated PDFs — after generating an invoice, report, or shipping label, confirm every page is the expected size.
• Debug PDF generation libraries — when a template renders incorrectly, check whether the page dimensions match the intended paper size.
• Detect mixed-size issues — automated reports sometimes merge pages from different templates, producing a mixed-size PDF that prints badly.
• Verify print-ready documents — printers require exact paper sizes; even 1 mm of drift can cause alignment problems on pre-printed stationery.
• QA document conversion — converting Word to PDF, HTML to PDF, or EPUB to PDF can silently change page dimensions.
• Compare PDF versions — diff two builds of a generated PDF by checking whether their page sizes match.
• Automate CI checks — extract the JSON report and assert page sizes in an automated test suite.

Common PDF page size problems

• Mixed page sizes — a common bug when merging documents or concatenating generated PDFs from different templates.
• Unexpected orientation — a page that should be portrait renders as landscape because of a rotation flag, a swapped MediaBox, or a generator default.
• Custom sizes masquerading as A4 — a template set to 216 × 279 mm instead of 210 × 297 mm looks like A4 at a glance but isn't.
• Cropped scans — a scanned document may have a CropBox smaller than the MediaBox, making it appear to have a different page size than it was scanned at.
• Letter vs A4 mismatches — documents prepared for one region print badly in another when the paper size differs.

Privacy and processing

Everything on this page runs locally in your browser. Your PDF file is read from disk into memory, parsed with a WebAssembly PDF engine that runs in the browser tab, and discarded when you reload or clear the page. Nothing is uploaded, nothing is logged, and no analytics event contains the file name, file size, page content, or page dimensions. The tool works offline once the page has loaded.

Because the parser runs client-side, there is no server-side size limit. Very large PDFs may be slow to parse in a memory-constrained browser, but the tool warns you rather than silently failing. Password-protected PDFs cannot be inspected without the password — the tool will tell you so rather than attempting to bypass the encryption.

Related developer tools

• Hash Generator & Checksum Tool — compute a SHA-256 checksum for the PDF file itself to verify integrity.
• Universal Data Transformer — convert the JSON report into CSV, YAML, XML, or SQL for processing.
• JSON Diff — compare two page-size reports to find what changed between PDF versions.
• Base64 Encoder & Decoder — decode embedded PDFs that arrive Base64-encoded in API payloads.
• API Request Builder — fetch PDFs from an API and inspect headers before downloading.
• UUID Generator & Validator — generate IDs for batch PDF processing jobs.
• JSON vs XML comparison guide — background on data formats if you're exporting reports.

Frequently asked questions

What is a PDF page size?

The physical dimensions of one page in the PDF, measured in points (1/72 inch) in the page's coordinate system. Common sizes are A4, Letter, and Legal, but PDFs can use any dimensions.

How do I check the size of a PDF page?

Drop the PDF into the upload area above. The tool reads the MediaBox dimensions of every page and reports them in mm, cm, inches, or points.

What is the standard A4 PDF size?

210 × 297 mm, which is 595.28 × 841.89 points, or 8.27 × 11.69 inches.

What is the size of an A4 PDF in pixels?

There is no fixed pixel size — pixels depend on the target DPI. At 72 DPI, A4 is 595 × 842 px. At 150 DPI, it's 1240 × 1754 px. At 300 DPI, it's 2480 × 3508 px.

What is the difference between A4 and Letter?

A4 is 210 × 297 mm (8.27 × 11.69 in); Letter is 215.9 × 279.4 mm (8.5 × 11 in). A4 is narrower and taller. They're both common defaults in different regions.

How do I know if a PDF is A4?

Upload it to this tool. If every page reports "A4" in the Size column, the document uses A4. If any page shows "Custom", that page's dimensions are outside the tolerance for A4.

Can a PDF contain different page sizes?

Yes. PDF allows every page to have its own MediaBox. Mixed-size PDFs are common when merging documents, combining templates, or including fold-outs. This tool detects and reports them.

Can a PDF contain portrait and landscape pages?

Yes. Orientation is determined per-page from the dimensions. A single PDF can contain both, and this tool reports each one separately.

What is a PDF point?

A unit in the PDF coordinate system. 1 point = 1/72 inch. All PDF page dimensions are internally expressed in points.

How many points are in an inch?

72. This is fixed by the PDF spec and matches the traditional typographic point.

What is the difference between MediaBox and CropBox?

MediaBox is the physical page boundary (the paper size). CropBox is the region the viewer displays by default, which may be smaller. This tool reports MediaBox as the page size.

Does PDF page size affect printing?

Yes. If the PDF page size differs from the paper loaded in the printer, the output will either be scaled to fit or clipped. Matching the PDF size to the physical paper avoids surprises.

Can I check PDF dimensions without uploading the file?

Yes — that's exactly what this tool does. The PDF is parsed entirely in your browser. Nothing is transmitted anywhere.

Does this tool upload my PDF?

No. All parsing happens client-side using a WebAssembly PDF engine. The file never leaves your browser tab.

Can I check a large PDF?

Yes, up to the practical memory limits of your browser. Very large PDFs (>500 MB) may be slow or fail on constrained devices; the tool warns you clearly rather than hanging silently.

Can I check a password-protected PDF?

Only if you supply the password. The tool does not attempt to bypass encryption. Password-protected PDFs without the correct password will show a clear error.

What does "Custom" mean?

The page dimensions do not match any known standard paper size within the tolerance (±2 mm). The exact dimensions are still reported.

Does page rotation change the PDF page size?

No. Rotation is a display property; it changes how the page is shown, not the physical page dimensions. The tool reports both separately.

Does PDF page size tell me the image DPI?

No. Page size is a physical dimension; DPI is a property of embedded images. This tool measures page size only.