DPI calculator
Estimate the image's pixel density at a planned print width. The result is pixels per inch (PPI), often called image DPI; it is not the printer's physical dot resolution or a required-pixels lookup.
Result
Resulting DPI
How to use this tool
- Enter the image's pixel width.
- Enter the width you're planning to print it at.
- Read the estimated pixel density at that print width.
Assumptions
- 300 DPI is generally considered photo quality for close viewing; 150 DPI is acceptable for larger prints viewed from further away, like posters.
Sources & reference data
Technical details: what the fields mean
- Image width
pixelWidth - The image's width in pixels — check its file properties.
- Intended print width
printWidthInches - How wide you're planning to print the image.
Methodology
Estimated image PPI at the intended print width = image width in pixels ÷ print width in inches. PPI describes image pixels per inch; printer DPI describes device dots per inch. The tool's output is labelled DPI for the familiar print-resolution query, but the pixel-to-size calculation is an image PPI estimate.
Worked example
3600px wide image printed at 12 inches
Inputs: Image width: 3600 px, Intended print width: 12 in
Result: 300 DPI
A 6000px-wide camera photo: how big before quality drops?
Inputs: Image width: 6000 px, Intended print width: 20 and then 40
Result: 300 DPI at 20in wide (photo quality held in the hand); 150 DPI at 40in wide (fine for a poster viewed from a few feet away).
Printing in centimetres: a 3508px image across A4's 21cm width
Inputs: Image width: 3508 px, Intended print width: 8.27 (21cm ÷ 2.54)
Result: 424 DPI — more than enough. Convert cm to inches by dividing by 2.54 (1 inch is exactly 25.4mm).
Practical guidance
- Below about 150 DPI, prints viewed up close start to look visibly pixelated — for a poster viewed from a distance, this matters much less.
- Upscaling an image in software raises the DPI number but doesn't add real detail; judge quality from the original pixel width.
- If the image will be cropped to fit the print's shape, use the pixel width left after cropping, not the original.
Common mistakes
- Judging print quality purely from megapixel count without considering the actual intended print size — the same image file can be photo-quality at one size and too low-resolution at a larger one.
FAQs
What DPI will my image print at?
Divide the image width in pixels by the intended print width in inches to estimate image PPI at that size. This page labels the result DPI, a common shorthand for image print resolution; printer DPI is the device's dot density. For the pixel dimensions needed for a target print, use the photo print-size calculator.
Does viewing distance really change the DPI I need?
Yes. The further away a print is viewed, the less detail the eye can resolve, so large prints viewed from across a room look sharp at much lower DPI than a photo held in the hand. That's why 300 is a common target for small prints and 150 or less is often fine for posters and banners.
Last reviewed: 2026-10-11
A straightforward pixels ÷ inches calculation — whether a given DPI 'looks good enough' also depends on viewing distance and print medium.
This tool provides an indicative estimate, based on the assumptions stated above.
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