Image Size and Resolution Calculator
Enter the pixel dimensions of an image and this calculator reports how large it prints, how many megapixels it holds, and how much space it occupies uncompressed.
How to find the resolution of an image
The resolution of an image is its pixel dimensions — width × height. Read them from the file properties in your operating system, from the title bar of an image editor, or from the info panel of any photo app.
Those two numbers determine everything else: the megapixel count is width × height ÷ 1,000,000, the aspect ratio is the two numbers reduced to their simplest form, and the printed size is each dimension divided by the DPI you choose.
Worked with the values in the calculator above
width = 3,000 px ÷ 300 DPI = 10 in
height = 2,000 px ÷ 300 DPI = 6.6667 in
cm = 10 in × 2.54 = 25.4 cm How large is an image file?
Uncompressed, an image occupies roughly width × height × 3 bytes for 24-bit colour. A 24-megapixel photo is therefore about 69 MB in raw form, and far less once JPEG or WebP compression is applied — typically 5 to 15 per cent of that for photographic content.
File size on disk tells you very little about print quality. A heavily compressed 24-megapixel photo still has 24 million pixels to print with.
Frequently asked questions
How do I determine the resolution of an image?
Check the file properties or open it in any image editor: the width and height in pixels are the resolution. Enter them above to see the printed size, megapixels and file weight.
How do I calculate image size based on pixels?
Divide each pixel dimension by the DPI you plan to print at. A 3000 × 2000 px image at 300 DPI prints 10 × 6.67 inches.
How many pixels per inch is high resolution?
300 pixels per inch is the professional print standard. Below about 150 PPI an image begins to look soft when held at reading distance.
What is image resolution measured in?
Two different things share the word. Pixel resolution is a count — 1920 × 1080. Output resolution is a density — 300 DPI. You need both to know how large something prints.
Does a bigger file mean a better image?
No. File size depends mostly on compression settings and image content. The pixel dimensions decide how large you can print, not the megabytes.