6 Replies Latest reply on Jul 18, 2017 3:54 AM by Bob_Hallam

# images sizes

Hi, i am having a lot of confusions about image resize for large print for weeks.

Is there an easy way to determine and to resize a picture for large format print? a rule of thumb? what works best most of the time? what resolution?

• ###### 1. Re: images sizes

Yes there is a formula for working out the required resolution and it is all based on viewing distance.

With good eyes and good light the formula is :

Print resolution in ppi = 2/(distance x 0.000291)

where "distance" is the viewing distance in inches, and ppi is pixels per inch

Here is an article which discusses resolution requirements

Dave

• ###### 2. Re: images sizes

all in inches?

• ###### 3. Re: images sizes

Yes that formula uses inputs in inches and gives resolution in pixels per inch

Dave

• ###### 4. Re: images sizes

A few examples.

First a print in an album to be viewed from 2 feet = 24 inches.

ppi required = 2/(24*.000291)  = 286ppi so approx. 300ppi

Second a wall print to be viewed from 4 feet = 48 inches.

ppi required = 2/(48 x 0.000291) = 143 pixels per inch

Third a billboard poster to be viewed at 10 yards = 30 feet =360 inches

ppi required  = 2/(360 x .000291) = 19ppi

Anything above those resolutions will not be visible, i.e. is wasted, at those viewing distances

I hope that helps you

Dave

• ###### 5. Re: images sizes

So, the distance i have to guess

• ###### 6. Re: images sizes

Standard rule of thumb is 300dpi.  Most images we get for large or grand format are 300dpi at 100% size because you can't guess viewing distance.  For Grand and up 150 works for the very large graphics over 10 ft.