What 300 DPI actually means for your photo
DPI — dots per inch — is how densely ink lands on the card. Three hundred dots per inch is the threshold where a print looks crisp to the eye; below it, detail starts to soften.
Multiply the card's dimensions by 300 and you get the pixel size your image needs to fill it at full quality: 2.5 inches times 300 is 750 pixels, 3.5 inches times 300 is 1050 pixels. So 750 x 1050 pixels is the floor.
Why you should aim higher than the floor
Almost no photo is used uncropped. The card builder crops your image into the card frame, and cropping throws pixels away — crop in by a third and your effective resolution drops by a third.
That is why the practical rule is 1000 pixels or more on the short side. It leaves comfortable room to crop and still print at full quality.
- ✓750 x 1050 pixels — the bare minimum at 300 DPI, no cropping
- ✓1000+ pixels on the short side — safe with normal cropping
- ✓Modern phone photos — typically 3000+ pixels, far more than needed
- ✓Screenshots and social downloads — often below the floor
The DPI number in the file does not matter
Here is the part that confuses people: the DPI value saved inside an image file is just a label. A photo does not get sharper because its metadata says 300 instead of 72.
What matters is the total pixel count relative to the print size. A 3000 x 4000 pixel photo prints beautifully on a card whether its metadata says 72 DPI or 300 DPI — the pixels are what print.