Large prints are seen from further away, so they need far fewer pixels per inch than a flyer. Enter the size and the viewing distance to get the resolution and image size to aim for.
How the calculator works
Normal eyesight can just separate details that are about one arc minute apart. At a viewing distance of d inches, that is a detail of d divided by 3,438 inches, so the resolution that looks sharp is 3,438 divided by d pixels per inch. A banner read from 10 feet (120 inches) needs 3,438 ÷ 120 = about 29 DPI. The calculator then multiplies that by the banner size to get the image size in pixels.
A 6 x 3 foot banner viewed from 10 feet therefore needs about 29 DPI, or roughly 2,063 x 1,031 pixels. The same banner at 300 DPI would be 21,600 x 10,800 pixels, which is more than 10 times as many pixels in each direction, with no visible gain from that distance.
A rule of thumb, not a guarantee
The figure assumes good eyesight and a viewer who is actually at that distance. People often step closer to read details, so for text and fine logos it is safer to aim a little higher, and vector artwork avoids the question altogether. Check the minimum your printer asks for, because some require 72 or 100 DPI at full size whatever the viewing distance.
For smaller prints, use the print size and DPI calculator, and for the artwork margins, the bleed and trim calculator. Banner and sign materials are heavier than paper, and the paper weight converter includes the ounce-per-square-yard unit used for banner vinyl.
Frequently asked questions
What resolution do I need for a banner?
It depends on how far away people will stand. A good guide is to divide 3,438 by the viewing distance in inches. A banner read from 10 feet (120 inches) needs about 29 DPI to look sharp, while a poster read from 3 feet (36 inches) needs about 95 DPI. The calculator does this for you and gives the image size in pixels.
Why is the number so much lower than 300 DPI?
The 300 DPI rule is for prints held in the hand, a foot or so from your eyes. The further away you are, the smaller the detail your eye can resolve, so a large print viewed from a distance looks just as sharp at a much lower resolution. Supplying 300 DPI at banner size makes the file enormous and gives no visible improvement.
Where does the 3,438 come from?
It comes from the sharpness of normal eyesight, which can separate details about one arc minute apart. At a distance d, that is a detail of d divided by 3,438. It is a rule of thumb for good vision, so it is on the demanding side and a little lower resolution often looks fine too.
Should I design at the full banner size?
You can, but many designers build at half or a quarter of the size and scale up, especially for very large signs, to keep files manageable. What matters is the effective resolution at the final size, which is the figure this calculator gives. Vector artwork such as logos and text scales to any size without losing sharpness.
Does my printer need a different resolution?
Possibly. Some wide-format printers ask for a specific resolution for a material or a minimum such as 72 or 100 DPI at full size, and they may want extra margin for hems, grommets and pole pockets. Use their template and instructions first, and use this calculator to check your image against them.
How big will the file be?
The calculator shows the uncompressed size of the image at the resolution it recommends, which is the pixels multiplied by three bytes for colour. Saved files such as JPEG or PDF are usually much smaller, but the uncompressed figure shows how heavy the artwork is while you work on it.
