Business card at 300 DPI: 1050 by 600 pixels

The physical size is 3.5 by 2 inches, the North American standard, and at 300 dots per inch that converts exactly to 1050 by 600 with no rounding. The greatest common divisor is 150, leaving a clean 7:4 ratio at 1.75:1, which sits between 16:9 and 3:2 and is wider than either most people expect.

This is not the only standard card. The widely used international size is 85 by 55 millimetres, which is a different shape at about 1.545:1, and there are national variants beyond that. A design laid out at 7:4 does not drop into an 85 by 55 template without a crop, so confirm the size with the printer before laying anything out.

Cards get trimmed from a larger sheet and the cut is not perfect, so two margins matter. Bleed extends the artwork beyond the trim line, commonly by an eighth of an inch or three millimetres, which is roughly 37 pixels at this resolution. A safe margin pulls text inward from the trim by a similar amount so a slightly off cut does not shave a letter.

That leaves less usable area than the canvas suggests. Subtracting a safe margin from each side of a 1050 by 600 card leaves something closer to 975 by 525 for content, which is why cards with a rule or a border close to the edge so often come back looking uneven.