Print Size & DPI Calculator (px, pt, mm, inch, bleed)

Converts px, pt, mm, cm and inches at a chosen DPI, finds the pixels a print size needs or how large an image can be printed, and shows trim, bleed and safe-area sizes for cards, paper and posters.

How to use

1. On "Unit conversion", enter a "Value", pick its unit and a "DPI"; the other units appear at once.
2. On "Required resolution", choose a "Print size" and a "Target DPI" to see "Pixels needed".
3. To check a photo, enter its "Image width" and "Image height" on the same tab; the table gives the largest print at 150, 200 and 300 DPI.
4. On "Trim and bleed", pick the "Print size", set "Bleed" and "Safe margin" and read the diagram.

How it works

• 1 inch = 25.4 mm, 1 pt = 1/72 inch, px = inches × DPI. At 96 DPI one pixel is 0.2646 mm and 12 pt is 16 px.
• Pixels needed = mm ÷ 25.4 × DPI, rounded. At 300 DPI an A4 sheet (210 × 297 mm) is 2480 × 3508 px.
• Detail labels use the effective DPI: 300 or more is "Sharp", 150 to 299 "Acceptable", below 150 "Coarse".
• Bleed is the outer area cut away after printing; the safe area is where text and logos stay. Both default to 3 mm.

Questions and answers

How many pixels is a business card at 300 DPI?

A 90 × 50 mm card is 1063 × 591 px. With 3 mm of bleed on every side (96 × 56 mm) it is 1134 × 661 px.

What is the formula to convert px to mm?

mm = px ÷ DPI × 25.4. At 96 DPI, 100 px is 26.46 mm; at 300 DPI it is 8.47 mm.

Do I really need 3 mm of bleed?

When colour runs to the edge of the paper, yes: cutting can shift by about a millimeter and bleed prevents a thin white edge. A design with a white border can often do without it.

Will a phone photo look pixelated on an A4 print?

A 4000 × 3000 px photo on the 210 mm short side of A4 gives about 363 DPI, in the sharp range. Enter the pixel size on "Required resolution" to check any size.