PDF to JPG Quality, DPI and File Size

What DPI means for a PDF page

A PDF page is not made of pixels — it is a set of drawing instructions measured in points, where 72 points equal one inch. To turn a page into an image, the renderer chooses how many pixels to use per inch. That number is the DPI.

Rendering at 72 DPI gives exactly one pixel per point. Rendering at 300 DPI gives about four times as many pixels across, which is why print-ready images are heavier.

What each setting gives you

JPEG compression quality

JPG is a lossy format. After the page is rendered to pixels, the encoder decides how much fine detail to throw away. At 85% the difference is usually invisible on screen; at 70% you start to see soft edges around small text; at 95% the file grows quickly for a small gain in sharpness.

• Smaller file uses about 70% compression — smallest images, some softness on fine text.
• Standard uses about 85% — the sensible default for almost everything.
• High quality uses about 95% — keep this when the image will be printed or enlarged.

Choosing a setting for your job

• Posting a page on a website or in a presentation: 150 DPI, balanced compression.
• Sending a page by email: 72 DPI if the recipient only needs to read it.
• Printing a page or filing it as a record: 300 DPI, high compression quality.
• Running text recognition on the result: 300 DPI gives OCR the most to work with.

Why a higher DPI is not always better

Every extra pixel has to be drawn and then encoded. A big page at 600 DPI can produce an image far larger than any browser canvas allows, so the converter automatically caps the render and tells you when it had to. On a phone, staying at 150 DPI keeps conversions fast and memory comfortable.

If you need a specific resolution and the converter reports a cap, convert the document in a smaller page range, or lower the DPI and scale the result up afterwards in an image editor.