Free image DPI converter

Forms ask for dots per inch because they are really asking how big the picture is on paper. A 600 by 600 photo at 300 dpi prints two inches across; the same photo at 200 dpi prints three. This tool writes that number into the file where a checker reads it — the JFIF header of a JPG, the pHYs chunk of a PNG — and can resize the pixels at the same time so the printed size comes out exactly as the form demands. It also tells you what your file says today, which for anything made by a phone or a web tool is usually nothing at all. Nothing is uploaded: the work happens inside your browser, on your own device.

How to use it

1. Drop the photo or signature JPG, PNG, WebP and HEIC all work, and several at once is fine.
2. Type the resolution 200 and 300 are one tap away. The line underneath shows what the file says now and what it will say afterwards, with the printed size in centimetres.
3. Choose what should change Writing only the number keeps every pixel and changes the printed size. Keeping the printed size resizes the pixels instead. The third option gives you an exact size in centimetres at that resolution — what a form like CCC means by "3.5 × 4.5 cm at 200 dpi".
4. Save it Add a KB limit if the form has one, and the result is compressed to fit with the resolution still written in.

Questions

How do I change the DPI of an image to 200 or 300?

Drop it above, tap 200 dpi or 300 dpi, and press Set the DPI. The number is written into the file itself, so Photoshop, a print shop or a form validator all read it back correctly.

My CCC form wants a 200 dpi photo. What do I do?

Choose "Make it an exact printed size", set 3.5 by 4.5 cm and 200 dpi, and add the KB limit the form states. You get a 276 by 354 pixel JPG that says 200 dpi and fits the size limit — which is exactly what the form is checking.

Does changing the DPI make my photo sharper?

On its own, no. Dots per inch is a label saying how large to print the pixels you already have. If you ask to keep the printed size, the tool does resize the picture, but enlarging cannot invent detail that was never photographed — start from the largest original you have.

Why does my photo say 96 dpi, or nothing at all?

Because most phones and web tools never write the field. A picture with no resolution recorded is usually assumed to be 96 dpi by Windows and 72 dpi by older Mac software, which is why the same file prints at different sizes in different places. Writing the number removes the guesswork.

What is the difference between DPI and pixels?

Pixels are how much picture there is; dpi is how tightly they are packed when printed. 1200 pixels at 300 dpi is four inches of paper. Forms usually state both, because together they fix the printed size.

Is the photo uploaded anywhere?

No. The file is read, edited and saved on your own device.

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