DPI Calculator

DPI calculator divides pixels along one side by the physical inches of that side. The opening pair is 3000 and 10, and the line reads DPI / PPI: 300.

Four divisions

3000 divided by 10 is 300. 1920 divided by 10 is 192. 100 divided by 2.5 is 40. 3000 divided by 8.5 is 352.941, and one decimal place displays 352.9. The same division is used for every pair, and the label on the result line is DPI / PPI. The fields are Pixels (one side) and Physical size (inches). The button reads Calculate. Zero or a negative pixel count throws Pixels and inches must be positive. Zero inches throws the same sentence. A blank field throws Enter a valid number. The display keeps one decimal, then drops a trailing zero, so 300 is not 300.0. There is no second side. Width and height are separate presses. There is no paper-size menu.

What one side means

The number is pixels per inch for the side you typed. It is not a print preset. A 3000 pixel side that is 10 inches long is 300 pixels per inch on that side. The other side can differ if the physical size differs. Aspect Ratio Calculator answers a ratio of two pixel sides and does not divide by inches. This page does not change a picture file. The picture-size page is a different upload. Type the inches of the side you measured, not the diagonal, unless the pixel count is also the diagonal. The opening pair 3000 and 10 is the check for a round 300. 100 over 2.5 is the check for a result of 40.

How to check 300

Leave 3000 and 10 and press Calculate. The line should be DPI / PPI: 300. Change inches to 8.5 and expect 352.9. Change pixels to 0 and expect the positive-number error, not a huge result. The step on the inches field is 0.01, so hundredths are accepted. A result with one decimal is the display, not a second rounding you can choose. 1920 pixels over 10 inches reads 192. 100 pixels over 2.5 inches reads 40. Those pairs use the same division as the opening 3000 and 10. There is no paper-size menu, so letter and A4 are not choices on this form.

The two numbers stay in the tab

The division runs in this browser. The pixels and inches are not uploaded. The formula was last checked in October 2026. Nothing is stored when you leave. Press Calculate again after you change either field. The button is the word Calculate. The line always starts with DPI / PPI and a colon. A blank inches box stops on Enter a valid number, and a zero on either field stops on Pixels and inches must be positive. 3000 pixels over 8.5 inches displays 352.9. The fields are labeled Pixels (one side) and Physical size (inches). One press covers one side only, so the other side needs its own inches. A trailing zero is dropped, so 300 is not printed as 300.0.