Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate an image's DPI (dots per inch) from its pixel dimensions and print size.
This tool calculates an image's DPI (dots per inch) -- a measure of print resolution -- by dividing its pixel width by the intended print width in inches. Higher DPI generally means sharper printed output; 300 DPI is a common target for high-quality print.
Enter the image's pixel width and the intended print width in inches. The resulting DPI appears instantly.
The tool divides one pixel measurement by one physical measurement in inches. The first field is labeled pixel width or height, and the second is the intended print size in inches along that same side. The answer is shown as a whole number followed by DPI. If the print size is zero or less, the tool shows a message that the print size cannot be zero instead of a result.
DPI = pixels ÷ print size in inches
Use the same side for both fields. If you enter the pixel width, enter the print width. If you enter the pixel height, enter the print height. Mixing them gives a meaningless number.
A photo that is 3,000 pixels wide printed 10 inches wide gives 300 DPI, a commonly cited target for sharp photo prints. The same 3,000 pixel photo stretched to 20 inches wide gives 150 DPI, which may be acceptable for something viewed from a distance but is noticeably softer up close. A 1,200 pixel wide web image printed at 6 inches wide gives 200 DPI. A hypothetical 800 pixel image printed at 8 inches wide gives 100 DPI, a level at which pixelation will usually be visible.
You can rearrange the same relationship yourself. To find the largest print size at a chosen DPI, divide the pixel count by the DPI. For instance, a 2,400 pixel wide image at 300 DPI supports a print of 8 inches wide. To find the pixels you need for a given print size, multiply the inches by the DPI, so a 12 inch wide print at 300 DPI needs 3,600 pixels across. Doing these before you shoot, scale, or commission artwork avoids surprises later.
There is no universal cutoff. Many print shops and guides mention roughly 300 DPI for close-viewed photos and lower values for large formats viewed from farther away, but the right number depends on the printer, the paper, the subject, and the viewing distance. Photographs with soft detail tolerate lower values better than sharp text or line art. Some printers have their own published minimum. For an important job, ask the print provider what resolution they recommend and follow their specification rather than a general rule of thumb.
For images displayed only on screens, the DPI number is not what determines sharpness. What matters is whether the image has enough pixels for the size it is shown at, including on high-density displays. If you are preparing images for a website, focus on pixel dimensions and file weight rather than a DPI value. This tool is most useful when something will be physically printed.
300 DPI is a common standard for high-quality print (photos, brochures); 150 DPI is often acceptable for larger-format prints viewed from a distance (posters, banners). Web images only need 72-96 DPI since screens don't use physical dots per inch the same way.
No, the print size field expects inches. Convert centimeters to inches by dividing by 2.54 before entering the value.
Either, as long as both fields refer to the same side. The pixel width goes with the print width, and the pixel height goes with the print height.
Only changing the DPI tag without resampling does not add detail. It only changes the default print size stored in the file.
The result is rounded to a whole number for readability, which is more than precise enough for print planning.