When you need this calculator
Before ordering prints, sending artwork to a printer, or buying a frame. You know the image’s pixel dimensions (right-click → Properties, or Get Info on a Mac); you need to know how large it will print without looking soft.
Reading the results
- Print size is exactly how big the image comes out at the DPI you entered.
- Largest sharp print (300 DPI) is the size to aim for when quality matters most.
- Megapixels is the pixel count, width × height ÷ 1,000,000. It’s handy for comparing cameras, but print size depends on the width and height separately.
Viewing distance matters
People look at a small photo from about 30 cm and a poster from a meter or more. The further away, the fewer DPI you need for the same apparent sharpness. That’s why a 150 DPI poster can look as crisp as a 300 DPI postcard.
Common mistakes
Printing a web image. Images saved for websites are often around 1200 px wide, which is only 4 inches (10.16 cm) at 300 DPI.
Upscaling to “make it 300 DPI”. Resampling a small image to more pixels doesn’t add detail. It only smooths what’s there. Start from the largest original you have.
Ignoring the crop. If the print shape differs from the image’s aspect ratio, part of the image is cropped. Check with the aspect ratio calculator.