Find how many centimeters an existing poster image, canvas artwork or photo can cover at your chosen PPI. Compare the result with a metric frame or an A-series paper size without changing the original pixels.
Measure an existing artwork in centimeters
- Enter the artwork’s actual pixel width and height.
- Choose the target PPI and compare with A4, A3, A2 or custom canvas dimensions.
- Read the calculated centimeters and any difference from your target; keep the original pixels unchanged.
From pixels to inches, then centimeters
First divide pixels by PPI to find inches. One inch is exactly 2.54 cm, so cm = px ÷ PPI × 2.54. A 2400-pixel edge at 300 PPI is 8 inches or 20.32 cm. A 2400 × 3000 image therefore spans 20.32 × 25.4 cm at that density.
A nominal 20 × 25 cm frame has the same 4:5 shape, but its slightly smaller placement produces about 304.8 PPI. A 21 × 29.7 cm A4 target has a different shape; distinguish the size shortfall from the crop or padding needed.
Compare with metric paper and canvas sizes
A4, A3 and A2 are target rectangles, not instructions to change the image’s pixel count. For a canvas print, confirm whether the supplier’s dimensions include the wrapped edges; those edges can consume part of the visible composition.
| Target | Centimeters | What to check |
|---|---|---|
| A4 | 21 × 29.7 | Crop or padding and density |
| A3 | 29.7 × 42 | Larger placement lowers effective PPI |
| A2 | 42 × 59.4 | Inspect viewing distance and original detail |
Choose the visible area before ordering
For a metric photo frame, compare both dimensions rather than only the long edge. Filling a different ratio crops content. Fitting the whole image leaves margins. Neither behavior should be hidden by presenting a single “print ready” label.
More decimal places do not improve the artwork. Copy the assumed PPI and target size with the result, and use a proof when the material or colour matters.
Image pixels and CSS pixels
CSS defines 96 CSS pixels per CSS inch for layout. That relationship is not the physical density of every screen, nor a required density for a printed image. Here, PPI is your explicit print assumption; browser zoom does not change the file’s stored pixels.
Frequently asked questions
How wide is 2400 pixels in centimeters at 300 PPI?
20.32 cm. Divide 2400 by 300, then multiply the 8-inch result by 2.54.
Does an A4 preset resize my poster?
No. It compares your existing pixels with a 21 × 29.7 cm target. Use an image editor only when you intend to change the file.
Should canvas wrap be part of the visible artwork size?
Ask the canvas supplier for its template. Wrapped edges and the front-facing area can require different dimensions and safe areas.