Pixels to print size: choose the PPI first
2400 pixels can mean 8 inches or 16 inches. Changing the density does not add detail.
A 2400-pixel-wide image prints 8 inches wide at 300 PPI, or 16 inches wide at 150 PPI. It is the same image. You are deciding how closely its pixels sit on paper.
Open the pixels-to-print converter. Set From unit to image pixels, To unit to inches and Pixel density (PPI) to 300. Enter 2400 in From value: the result is 8 inches. Change only the PPI to 150 and the result becomes 16 inches.
Pick a density, then calculate the size
PPI means pixels per printed inch. The calculation for one edge is:
print width in inches = image width in pixels / PPI
image width in pixels = print width in inches * PPI
Here are four results from the converter:
| Image width | PPI | Print width |
|---|---|---|
| 2400 px | 300 | 8 in / 20.32 cm |
| 2400 px | 150 | 16 in / 40.64 cm |
| 3000 px | 300 | 10 in / 25.4 cm |
| 2400 px | 300 | 203.2 mm |
We use 300 PPI as an example, not a requirement for every print. Ask the printer for its preferred resolution at the final size. A poster viewed from a distance and a photograph held in your hand have different needs.
The converter calculates a size; it does not edit the image or write resolution metadata. Adobe's explanation of image size and resampling distinguishes changing print dimensions from adding or removing pixels. A new PPI number alone cannot create extra detail.
Work backwards from the paper
Suppose you need an 8 × 10 inch image at 300 PPI. Choose inches as the source and image pixels as the destination. Convert each edge separately: 8 inches needs 2400 pixels, and 10 inches needs 3000 pixels.
For a full A4 sheet, 21 × 29.7 cm at 300 PPI gives about 2480.315 × 3507.874 pixels. Image dimensions must be whole numbers. Rounding each edge up gives 2481 × 3508 pixels if you need to meet at least 300 PPI on both edges. This is a calculation for the paper size only: bleed, trim and a printer's supplied template may require different dimensions.
Download the calculation sheet to check the unrounded A4 values and the inch examples.
Check the shape as well as the pixel count
A 2400 × 1600 image has a 3:2 aspect ratio. An 8 × 10 inch print has a 4:5 ratio. Enough pixels alone cannot make those shapes match.
To fill the print, use the crop tool to choose which edges to remove. To keep the whole image, allow borders instead. PDF essentials can fit images inside A4 or Letter pages without cropping, but it does not make the source sharper.
Image pixels and CSS pixels use different rules
For print calculations, use this tool's PPI setting. For web layout values such as px, rem and em, use the separate CSS units converter. CSS defines an inch as 96 CSS pixels; that relationship does not tell you the print density of a photo. MDN explains these CSS length units.
The results record contains the arithmetic checked against the tool on 26 October 2026. It verifies the conversions, not the sharpness of a particular print.