Image & design · Print
Poster resolution calculator.
Pixels needed for a poster from its size and how far away it is viewed, with an optional check of your own image.
Inputs
Resolution needed
Enter the poster size.
How many pixels does a poster need?
The eye resolves detail down to roughly 1 minute of arc under ideal conditions, and a 20/20 letter is built on that scale. If each pixel on the print covers 1 minute of arc, individual pixels are just at the edge of what you can see. The pixel density that does this is ppi = 1 / (distance x tan(1 arcminute)), about 3438 divided by the distance in inches. A 24 x 36 in poster seen from 3 ft (36 in) needs about 95.5 ppi, or 2292 x 3438 px.
Close viewing needs more: at 12 in the same formula gives about 286 ppi, which is close to the 300 ppi often quoted for small prints. Your printer or print shop may ask for a different number, so treat the result as a benchmark and follow their specification.
Frequently asked questions
What resolution should a poster be?
It depends on how close people stand. The viewing distance formula gives the ppi at which one pixel spans a chosen visual angle. For a 24 x 36 in poster viewed from 3 ft, 1 arcminute per pixel is about 95.5 ppi (2292 x 3438 px). Your printer may require more.
Why does a larger viewing distance need fewer pixels?
The further away you are, the smaller a pixel looks. Doubling the distance halves the ppi needed.
Can I upscale a small image for a poster?
Resizing adds pixels but not detail, so an upscaled image still looks soft up close. Check the verdict above against the resolution your image really has.
What are the sharpness choices?
1 arcminute per pixel is the common 20/20 benchmark (the typical minimum angle of resolution for an ideal eye). 2 arcminutes corresponds to 20/40 vision and a coarser print; 0.5 arcminute is for very close inspection or very sharp eyes.
How is this different from the megapixel calculator?
The megapixel calculator converts pixels and print size at a ppi you choose. This one starts from the viewing distance and works out the ppi for you.
Sources
Checked
- American Academy of Ophthalmology EyeWiki: Visual Acuity Testing in Adults (minimum angle of resolution)
- Printer Working Group: PWG 5101.1-2023, Media Standardized Names v2.1 (North American, photo, envelope and card sizes)
The 1 arcminute minimum angle of resolution and the 5 arcminute 20/20 letter are from EyeWiki (AAO); the 2 arcminute (20/40) value follows by doubling. Treating one pixel as one arcminute is a common benchmark, not a print standard, and printers often specify their own ppi. Runs entirely in your browser. Nothing you type is sent or stored.
Scope
Sizes and results are arithmetic on published paper sizes and the numbers you enter. Printers and print shops set their own sizes, margins, bleed and resolution requirements, so confirm with yours before you print.