As many of you know, the resolution of an image determines how clear or grainy it will look when you print it. As a general rule, any time you need to print an image, make sure it is 300 dpi. This post has an excellent explanation.

Okay great. But 300 dpi means nothing to me. Exactly how many pixels do I need to make the 4” x 6” image in my document print at 300 dpi?

Good question. And the answer requires only a little bit of math.

1 inch = 300 pixels, so a 4” x 6” image requires 1200 x 1800 px to print at 300 dpi. If you need your image to go the whole way across the top of a standard piece of US letter paper (8.5” x 11”), that means you’ve got to find an image that’s at least 8.5” wide, or 2550 px.

What if I want the image to go off the edge of the page?

When the image goes off the side of a page, that’s called “bleed”. Standard bleed size is 1/8 inch (or .125”). In pixels at 300 dpi, that’s 38 px. If your image bleeds off of just the left side of a page, add .125” or 38 px to your width. If your image bleeds off both the left and right edges, add another .125” for a total of .25” or 75 px to your final width. If you’re bleeding all over the place, add 75 px to your width and 75 px to your height.

Ex: 4" x 6" photo
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with no bleed:            1200 x 1800 px
bleeding on all 4 sides:  1275 x 1875 px

And just for easy reference, a handy inch-to-pixel conversion chart.

Inch-to-Pixel Conversion Chart

Printed Size Best: 300 dpi Okay: 250 dpi Lowest Acceptable: 200 dpi
In inches, w x h In pixels, w x h In pixels, w x h In pixels, w x h
1 x 1 in 300 x 300 px 250 px w x 250 px h 200 px w x 200 px h
2 x 2 in 600 x 600 px 500 x 500 px 400 x 400 px
4 x 6 in 1200 x 1800 px 1000 x 1500 px 800 x 1200 px
5 x 7 in 1500 x 2100 px 1250 x 1750 px 1000 x 1400 px
8 x 10 in 2400 x 3000 px 2000 x 2500 px 1600 x 2000 px
8.5 x 11 in 2550 x 3300 px 2125 x 2750 px 1700 x 2200 px
11 x 17 in 3300 x 5100 px 2750 x 4250 px 2200 x 3400 px
Add .125 in per side for bleed Add 38 px per side Add 31 px per side Add 25 px per side