DPI Calculator
DPI Calculator works out Print width and Print height from Image width, Image height and Pixel density to print at. The default figures on this page give pixel density of 250.00 ppi; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- ppi = 1000 px / 4 in = 250 ppi.
- That is 7.2 megapixels at an aspect ratio of 5:4.
- Capacity: 64 GB = 64000 MB; floor(64000 / 25) = 2560 photos.
Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the DPI Calculator calculates
Converts between image pixel dimensions, print size in inches or centimetres and pixel density, and works out how many photos of a given file size fit on a memory card.
How to use this DPI Calculator
Enter Image width, Image height, Pixel density to print at and Pixels along one edge. Print width updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Print width, Print height and Pixel density.
The method follows Definition of pixel density: ppi = pixels / inches of print, IEC 80000-13 decimal capacity units (1 GB = 1000 MB) as used by card manufacturers and Researched engineering contracts R789 (IMAGE-DPI), R799 (PRINT-SIZE) and the PHOTO-CAPACITY contract.
What you can compare
Change one input at a time to see how it affects Print width, Print height and Pixel density. The inputs you can vary are Image width, Image height, Pixel density to print at, Pixels along one edge, Print length of that edge and Card capacity.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How can I convert 800 DPI to 1600 DPI?
Converts between image pixel dimensions, print size in inches or centimetres and pixel density, and works out how many photos of a given file size fit on a memory card. Open “How this is worked out” beside the result to see each step for your own figures.
Is 800 or 1200 DPI faster?
Converts between image pixel dimensions, print size in inches or centimetres and pixel density, and works out how many photos of a given file size fit on a memory card. On the figures this page opens with — pixels along one edge 1,000 px and print length of that edge 4 in — the pixel density is 250 ppi. Put your own figures in their place and the working updates beside the result.
How can I calculate my DPI?
It needs Image width, Image height, Pixel density to print at, Pixels along one edge, Print length of that edge and Card capacity. Nothing else is required, and the figures stay in your browser.
What information do I need for the DPI Calculator?
You need Image width, Image height, Pixel density to print at, Pixels along one edge, Print length of that edge, Card capacity and Size of one photo. The page opens with default figures that give pixel density of 250.00 ppi, so you can see the scale before entering your own.
What does this DPI Calculator show?
It shows Print width, Print height, Pixel density, Megapixels, Aspect ratio, Photos that fit on the card and Card capacity, with the working and any warnings for your entries.
Can I check how the DPI Calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.