Updated 23 October 2026
Choose DPI and understand image resolution
Calculate output pixels from PDF page size and choose 72, 150 or 300 DPI with realistic clarity, file-size and memory tradeoffs.
Open PDF ConverterDPI sets how many pixels a page receives
For a normal PDF page, width in pixels is approximately width in inches × DPI. PDF page coordinates normally use 72 points per inch, so the converter scales the page by DPI ÷ 72. Rotation, page boxes and rounding can change the final integer dimensions slightly.
A US Letter page measuring 8.5 × 11 inches becomes about 612 × 792 pixels at 72 DPI, 1275 × 1650 at 150 DPI, or 2550 × 3300 at 300 DPI. These are pixel counts, not a promise that every image viewer will read a matching print-resolution metadata tag. Set the intended print size in your printing application.
Pick the smallest preset that fits the task
Use 72 DPI for fast draft previews and thumbnails. At full-page size, small type may be difficult to read. Use 150 DPI for everyday reading and sharing; it is a sensible first test when device memory is limited.
Use 300 DPI for dense small type or output intended for printing when you need more pixels. Vector text can benefit from higher rendering resolution. A low-resolution scanned page cannot gain new source detail simply by increasing DPI; it becomes a larger version of the same scan.
More pixels cost memory
Doubling DPI roughly doubles both width and height, producing four times as many pixels. A 2550 × 3300 page has 8,415,000 pixels; a four-byte RGBA canvas alone needs about 32 MiB, before PDF decoding, image encoding, previews and other browser overhead.
The converter applies page and rendering limits, but a device may run out of memory before reaching them. Many output pages also retain image blobs until you clear results. Try a short page range, lower DPI or fewer queued documents if the tab becomes slow.
Compare at the intended viewing size
Inspect small text, lines and diagrams at the size you will actually share or print. JPG and WebP use different encoder quality values for the DPI presets, so a DPI change affects both raster resolution and lossy compression in this converter.
PNG and BMP do not use that encoder-quality value; their resolution still changes with DPI. Keep a sample output and confirm its dimensions and readability before converting a large batch.