Convert a Long Screenshot Into a Paginated PDF
Converting a long image to PDF means cutting one very tall image, such as a full-page or chat screenshot, into horizontal bands whose proportions match a print page, then placing each band on its own page. This tool slices your image into A4- or Letter-proportioned bands of up to 60 pages and builds the PDF locally in your browser.
Full-page browser captures, exported chat threads, and scrolling-screenshot images from phones share a shape problem: they are one narrow strip thousands of pixels tall. Dropped into a normal image-to-PDF converter, that strip becomes either one enormous custom-size page that no printer accepts or a single A4 page where everything shrinks to an unreadable sliver. This tool takes the third route — it treats the strip as a sequence of page-shaped windows and gives each window its own page, so the result prints and reads like an ordinary document.
How it works
The slicing is pure geometry. After the image is decoded onto a canvas, the tool knows its pixel width w and computes the band height from the target page's aspect ratio: for A4 (210 × 297 mm content area) each band is w × 297⁄210 ≈ 1.414·w pixels tall; for US Letter (8.5 × 11 in) it is 1.294·w. The image is then read top to bottom in steps of that height. Each step copies one band region of the canvas — full width, band height — into its own bitmap. The final band is usually shorter than the rest; it is kept at its natural height and simply placed at the top of the last page rather than stretched, so nothing is distorted.
Each band is re-encoded and embedded into a new PDF built with pdf-lib. Pages are created at true A4 or Letter dimensions in PDF points (595 × 842 for A4, 612 × 792 for Letter), and each band image is scaled to fit the page's content box — the printable area inside a small margin — preserving its aspect ratio exactly. Because band width always maps to content-box width, effective print resolution equals image pixel width divided by printed width: a 1080-pixel-wide capture on A4 lands at roughly 140 DPI, and a 1440-pixel capture at about 185 DPI.
Two limits are worth knowing. The slicer caps output at 60 pages, which covers a screenshot up to about 85 screen-heights tall; anything beyond the cap is dropped, so split extreme captures first. And cuts happen at fixed intervals with no content awareness — a text line can straddle a page break, continuing on the next page. Everything runs in your browser: the image is decoded, sliced, and packed into the PDF on your own device, and no pixel of it is uploaded anywhere.
Worked example: a 21,000-pixel support chat
A support conversation exported as one PNG: 1170 pixels wide, 21,384 pixels tall, 4.6 MB. Choosing A4 gives a band height of 1170 × 1.414 ≈ 1654 pixels, so the strip yields ⌈21384 ⁄ 1654⌉ = 13 pages — twelve full bands plus a final 1536-pixel remainder placed at the top of page 13. Conversion takes two to three seconds and the resulting PDF is 5.1 MB, slightly larger than the source because thirteen separately encoded bands carry a little more overhead than one continuous PNG. Printed on A4, the chat text corresponds to about 150 DPI — comfortably legible — where the single-page alternative would have compressed the entire 18-screen conversation onto one sheet at around 8% of its on-screen size.
Frequently asked questions
How do I turn a long chat screenshot into a multi-page PDF?
Load the screenshot here, pick A4 or Letter, and the tool cuts the image into page-proportioned horizontal bands, one per PDF page. You download a normal paginated PDF instead of one absurdly tall page.
Why not just put the whole tall image on one PDF page?
A single page shaped like the image prints uselessly small when forced onto A4 paper, since the whole strip is shrunk to fit one sheet. Slicing keeps the content at readable size across several standard pages.
Does slicing the screenshot lose image quality?
Each band keeps the full pixel width of your original image; slicing only divides the height. Quality on paper therefore depends on the source: a 1080-pixel-wide capture yields roughly 140 DPI on A4, which reads fine for chat and web text.
What is the maximum number of pages the slicer produces?
60 pages. An image too tall for that limit still converts, but the bands beyond page 60 are dropped, so crop extremely long captures into two images first and convert them separately.
Can lines of text get cut in half at page breaks?
Yes, a break can land mid-line because the slicer cuts at fixed geometric intervals and does not detect text. Nothing is lost, though: the split line continues at the top of the next page.