Canvas size calculator for print
Enter print size in centimeters and DPI to get width and height in pixels before your first stroke. Add layer count to estimate PSD size and RAM use.
Calculator form
How to use
Pick a format
Enter width and height in cm or tap an A4, A3, or A5 preset.
Set DPI
Use 300 for quality prints, 150 for posters and large viewing distance.
Layers and bit depth
For PSD estimates, enter layer count and 8- or 16-bit channels.
Copy the result
Create a canvas at the calculated pixel size in your app.
Sample calculations
A4 at 300 DPI
21 × 29.7 cm → 2480 × 3508 px
A3 at 300 DPI
29.7 × 42 cm → 3508 × 4961 px
30 cm square
30 × 30 cm at 300 DPI → 3543 × 3543 px
Common mistakes
Mistake
Drawing at 72 DPI then upscaling to 300 → Set final DPI when you create the canvas.
Mistake
Ignoring bleed for trim → Extend background 2–3 mm past the trim line.
Mistake
8000 px canvas “just in case” → Extra pixels cause lag; match the deliverable size.
FAQ
What DPI do I need to print art?
300 DPI is standard for paper prints. Large posters viewed from far away often work at 150 DPI.
How many pixels is A3?
At 300 DPI, A3 (29.7 × 42 cm) is about 3508 × 4961 pixels.
Does DPI affect screen quality?
No. On screen only pixel dimensions matter. DPI maps pixels to physical print size.
Why is my PSD so large?
Each layer is full raster. Roughly width × height × 4 bytes (8-bit RGBA) × layers, plus overhead.
Can I shrink the file after drawing?
Downscaling is safe. Upscaling will not recover detail.
Source: Printful: DPI
Lock it in with practice
Open the free editor and apply the result — a short sketch beats more reading.