Change Image DPI to 300

Print labs and print dialogs often ask for a specific DPI. Changing that value is a metadata edit, not an image edit — and this page does exactly that. You can change image DPI to 300, or to any other value a lab asks for, without adding or removing a pixel.

Is 300 DPI required?

For a photo print, 300 DPI is the usual recommendation: at a normal viewing distance it gives a smooth result. But the DPI number alone does not make a print sharp. What matters is how many pixels you have:

• A 4000 × 3000 photo at 300 DPI prints at 13.3 × 10 inches with plenty of detail.
• A 800 × 600 photo at 300 DPI prints at only 2.7 × 2 inches; enlarging it will not add detail.

If a print needs to be both large and sharp, resize the image first, then set the DPI. The bulk image resizer handles the pixel side.

What the converter changes

The tool writes the new value into every place the format uses:

• JPG — both the JFIF header and the EXIF resolution fields, so viewers that read either location agree.
• PNG — the pHYs chunk, with the value converted to pixels per metre as the format requires.
• WebP — the EXIF resolution fields, because WebP has no field of its own.

The compressed image data is never decoded. There is no quality loss, no change to transparency, and no recompression.

Custom values

Beyond the three common presets, Custom accepts any whole number from 1 to 1200 DPI. Use it for a print shop that asks for 240 DPI, or for a scanner workflow that expects an unusual value.

Print size, from pixels to inches

At 300 DPI the arithmetic is simple: pixels ÷ 300 = inches, and inches × 2.54 = centimetres. Working backwards solves the common problem of a lab that names a paper size instead of a pixel size — multiply the inches by 300 to get the pixels you need.

Pixels	Inches at 300 DPI	Centimetres
1200 × 1800	4 × 6	10 × 15
2400 × 3000	8 × 10	20 × 25
3000 × 4500	10 × 15	25 × 38

If the target is 8 × 10 inches and the file holds only 1200 × 1500 pixels, writing 300 DPI does not fix it — the print will simply come out at 4 × 5 inches. Resize first, then set the value.

How to use it

1. Drop in the batch. JPG, PNG and WebP are accepted; other formats are refused with a reason.
2. Choose a target DPI. 300 is selected by default, matching the page’s purpose.
3. Convert. Each card reports the value before and after, and becomes downloadable.
4. Download. Save files individually, or export the batch as one ZIP.

Not sure what a file currently holds? The DPI checker reads the stored value and shows the print size it implies. If the job goes beyond resolution — clearing GPS coordinates or writing a copyright line — the EXIF editor works on the same batch, and image compression is the next step when a portal caps file size as well.