Is my image uploaded to make the PDF?

No. The PDF file is assembled byte-by-byte in your browser from the image you provide. It is never sent to any server.

How is the PDF built without a library?

The image is drawn to a canvas and exported as JPEG bytes, then embedded as a DCTDecode image object inside a minimal, spec-valid PDF (catalog, page, content stream and image XObject). The page is sized to the image at your chosen DPI.

Why is the output a JPEG inside the PDF?

JPEG (DCTDecode) is natively supported by the PDF format, keeps the file small, and works in every PDF reader. Transparent areas are flattened onto white because JPEG has no alpha channel.

How does DPI affect the page size?

The page is sized in points (1/72 inch). At 72 DPI each pixel maps to one point, so the page matches the screen size. At 150 or 300 DPI the same pixels are packed into a smaller physical area, giving a sharper print at a smaller page size.

Which DPI should I choose?

Use 72 for screen-only viewing, 150 for general documents, and 300 for high-quality printing. Higher DPI does not add detail your image lacks, but it sets the correct physical print dimensions.

Can I combine several images into one PDF?

This tool produces a single-page PDF sized to one image. To merge multiple images, convert each and then use a PDF merge tool, or place them in one image first.

What is the Image to PDF?

Free image-to-PDF converter. Turn any photo or screenshot into a single-page PDF sized to the image, with adjustable DPI and quality. Built entirely in your browser — nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

Image to PDF — Gera Tools

Name: Image to PDF
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Convert an image to PDF, privately

Wrap a photo, scan, or screenshot into a single-page PDF sized exactly to the image — useful for emailing a receipt, archiving a document scan, attaching a photo to a form that requires PDF, or turning a screenshot into a printable file. Everything happens locally, so sensitive documents never leave your device.

How it works under the hood

The image is drawn onto a <canvas> and exported as JPEG bytes at your chosen quality. Those bytes are then embedded as a DCTDecode image XObject inside a minimal but fully spec-valid PDF structure built directly in JavaScript:

Catalog object — required root of the PDF object tree
Page object — sized in PDF points (1/72 inch) from pixel dimensions ÷ DPI
Content stream — a single Do operator drawing the image at page coordinates
Image XObject — the raw JPEG bytes with the DCTDecode filter

The result opens correctly in every standard PDF reader. Because JPEG has no alpha channel, any transparent regions in the source image are flattened onto a white background.

DPI explained — choosing the right setting

DPI (dots per inch) sets how the pixel dimensions map to physical page size in the PDF. It does not add or remove detail; it only controls the printed size:

Source image	DPI	Page width	Physical size
1500 × 1000 px	72	1500 pts	≈ 20.8 × 13.9 in (screen)
1500 × 1000 px	150	720 pts	10 × 6.67 in
1500 × 1000 px	300	360 pts	5 × 3.33 in (print quality)

72 DPI — a PDF page that matches the screen pixel size. Good for purely digital documents where printing is unlikely.

150 DPI — a reasonable middle ground: a comfortable reading size and adequate print quality for most everyday documents.

300 DPI — standard print resolution. The page size becomes smaller (because more dots are packed into each inch), producing a sharp, publication-quality print from a sufficiently large source image.

Common use cases

Receipts and invoices: photograph the receipt, convert to PDF, attach to an expense form.
ID and passport scans: convert a JPG photo of the document to PDF for submission to services that require PDF format. Because this tool runs locally, your ID is never sent anywhere.
Screenshot-as-document: capture an on-screen form or confirmation, convert to PDF for your records.
Photo archiving: consolidate individual photos into a named PDF — though for multi-page books, convert each image individually and merge them afterward using a PDF merge tool.

The PDF is assembled entirely in your browser and your file is never uploaded.